Influence of the individual or combined application of biochar and slurry on soil macro-aggregate formation under varying moisture conditions

NASA Astrophysics Data System (ADS)

Kaiser, Michael; Grunwald, Dennis; Koch, Heinz-Josef; Rauber, Rolf; Ludwig, Bernard

2017-04-01

The formation of aggregates is of large importance for the structure and the storage of organic matter (OM) in soil. Although positive effects of organic soil additives on the formation of macro-aggregates (> 250 µm) have been reported, the influence of biochar especially applied in combination with other organic amendments remains unclear. Furthermore, studies on the effect of varying soil moisture conditions in form of drying-rewetting cycles on soil aggregate dynamics in the presence of biochar are almost missing. The objectives of this study were to analyze the effects of biochar and slurry applied to the soil individually or in combination on the formation of macro-aggregates under constant and under varying moisture conditions. We sampled four silty loam soils, carefully crushed the soil macro-aggregates, and incubated the soil at 15 °C for 60 days with the following additions: (i) none (control), (ii) biochar (12 % of dry soil mass), (iii) slurry (150 kg N ha-1), (iv) biochar (6 %) + slurry (75 kg N ha-1), (v) biochar (12 %) + slurry (75 kg N ha-1), (vi) biochar (6 %) + slurry (150 kg N ha-1) and (vii) biochar (12 %) + slurry (150 kg N ha-1). The samples were further subdivided into two groups that were incubated under conditions of constant soil moisture and of three drying-rewetting cycles. The CO2 fluxes were continuously measured during the incubation period and the samples were analyzed for microbial biomass C, macro-aggregate yields and macro-aggregate-associated C after finishing the experiment. We found the application of biochar to result in lower macro-aggregate yields with or without slurry compared to the control or the individual slurry application. In contrast, similar or higher C contents in the macro-aggregate fraction of the biochar treatments as compared to the control or slurry treatments were found indicating an occlusion of biochar in macro-aggregates. Due to the sorption characteristics of biochar, we assume the aggregate formation to be partially abiotic with direct interactions between biochar, (adsorbed) slurry, and the mineral phase of the soil. Therefore, in the presence of slurry, a prolonged period of microbial processing does not seem to be necessary to render the biochar suitable to form aggregates. Drying and rewetting of the samples resulted in significantly lower aggregate yields especially for the biochar/slurry mixtures. The drying of slurry as thought to be the most important macro-aggregate binding agent in these treatments might irreversibly disrupt large amounts of the macro-aggregates formed. Additionally, the general lower microbial biomass C and CO2 emissions for the samples experiencing drying-rewetting cycles compared to the constantly moist soils point toward less microbial activity under varying moisture conditions. This might have led to less microbial derived aggregate binding agents contributing to the lower aggregate yields found for the samples from the drying-rewetting treatments. Beside the amount and type of binding agents derived from organic soil additives, the formation and stability of soil macro-aggregate seem also to be controlled by climatically controlled soil moisture conditions.

PIXE analysis of sand and soil from Ulaanbaatar and Karakurum, Mongolia

NASA Astrophysics Data System (ADS)

Markwitz, A.; Barry, B.; Shagjjamba, D.

2008-09-01

Twenty-one sand and soil samples were collected at the surface from 22 to 25 June 2007 at sampling sites from Ulaanbaatar to Karakurum, Mongolia. The sand samples were collected from constantly changing sand dunes which may still contain salt from prehistoric oceans. The dry sand and soil samples were processed for PIXE and PIGE analyses. A clear division between soils and sand become apparent in the silicon results. Concentrations of all bulk elements in human habitation samples and of Si, Al, K and Fe in dry lake/flood plain samples are similar to those in the soils and sands. Among elements which could be regarded as being at trace concentrations the average S concentration in the soils is 0.9 g kg-1 whereas it is not detected in the sand samples. Zinc and Cu concentrations are both higher in the soils than the sands and are strongly correlated. A surprising presence of uranium at a concentration of 350 mg kg-1 was detected in the PIXE measurement on one of the dry lake samples. Gamma spectrometry confirmed the presence of U in this sample and also at a lower level in a sample from the lake shore, but in none of the other samples. Further, the gamma spectrometry showed that 238U decay products were present only at a level corresponding to about 3 mg kg-1 U for a system in radioactive equilibrium, a figure which is typical for U in the earth's crust. Disequilibria between 238U and its decay products occur naturally but such a high degree of separation at high concentration would be unique if confirmed. PIXE and PIGE measurements of these samples highlight the difficulty in correlating trace element measurements with occurrence of indicators of sea salt in air particulate samples.

Development of remote sensing techniques capable of delineating soils as an aid to soil survey

NASA Technical Reports Server (NTRS)

Coleman, T. L.; Montgomery, O. L.

1988-01-01

Eighty-one benchmark soils from Alabama, Georgia, Florida, Tennessee, and Mississippi were evaluated to determine the feasibility of spectrally differentiating among soil categories. Relationships among spectral properties that occur between soils and within soils were examined, using discriminant analysis. Soil spectral data were obtained from air-dried samples using an Exotech Model 20C field spectroradiometer (0.37 to 2.36 microns). Differentiating among the orders, suborders, great groups, and subgroups using reflectance spectra achieved varying percentages of accuracy. Six distinct reflectance curve forms were developed from the air-dried samples based on the shape and presence or absence of adsorption bands. Iron oxide and organic matter content were the dominant soil parameters affecting the spectral characteristics for differentiating among and between these soils.

Measurement of technetium-99 in Marshall Islands soil samples by ICP-MS

PubMed

Tagami; Uchida; Hamilton; Robison

2000-07-01

Extraction techniques for recovery of technetium-99 (99Tc) for Inductively Coupled Plasma Mass Spectrometry (ICP-MS) measurements were evaluated using soil samples collected from the Marshall Islands. The results of three different extraction techniques were compared: (MI) acid leaching of Tc from ashed soil; (M2) acid leaching of Tc from raw dry soil; and (M3) Tc volatilization from ashed soil using a combustion apparatus. Total Tc recoveries varied considerably between the extraction techniques but each method yielded similar analytical results for 99Tc. Applications of these extraction techniques to a series of environmental samples and ICP-MS measurements have yielded first data on the 99Tc content of Marshall Islands soil samples contaminated with close-in radioactive fallout from nuclear weapons testing. The 99Tc activity concentration in the soil samples ranged between 0.1 and 1.1 mBq g(-1) dry weight (dw). The limit of detection for 99Tc by ICP-MS was 0.17 mBq per sample or 0.014 mBq g(-1) dw under standard operating conditions.

Mechanical impedance of soil crusts and water content in loamy soils

NASA Astrophysics Data System (ADS)

Josa March, Ramon; Verdú, Antoni M. C.; Mas, Maria Teresa

2013-04-01

Soil crust development affects soil water dynamics and soil aeration. Soil crusts act as mechanical barriers to fluid flow and, as their mechanical impedance increases with drying, they also become obstacles to seedling emergence. As a consequence, the emergence of seedling cohorts (sensitive seeds) might be reduced. However, this may be of interest to be used as an effective system of weed control. Soil crusting is determined by several factors: soil texture, rain intensity, sedimentation processes, etc. There are different ways to characterize the crusts. One of them is to measure their mechanical impedance (MI), which is linked to their moisture level. In this study, we measured the evolution of the mechanical impedance of crusts formed by three loamy soil types (clay loam, loam and sandy clay loam, USDA) with different soil water contents. The aim of this communication was to establish a mathematical relationship between the crust water content and its MI. A saturated soil paste was prepared and placed in PVC cylinders (50 mm diameter and 10 mm height) arranged on a plastic tray. Previously the plastic tray was sprayed with a hydrophobic liquid to prevent the adherence of samples. The samples on the plastic tray were left to air-dry under laboratory conditions until their IM was measured. To measure IM, a food texture analyzer was used. The equipment incorporates a mobile arm, a load cell to apply force and a probe. The arm moves down vertically at a constant rate and the cylindrical steel probe (4 mm diameter) penetrates the soil sample vertically at a constant rate. The equipment is provided with software to store data (time, vertical distance and force values) at a rate of up to 500 points per second. Water content in crust soil samples was determined as the loss of weight after oven-drying (105°C). From the results, an exponential regression between MI and the water content was obtained (determination coefficient very close to 1). This methodology allows the prediction of the potential mechanical behaviour of soil crusts generated during soil drying, from initial saturated soil conditions (e.g. waterlogging conditions).

DRY–WET CYCLES INCREASE PESTICIDE RESIDUE RELEASE FROM SOIL

PubMed Central

Jablonowski, Nicolai David; Linden, Andreas; Köppchen, Stephan; Thiele, Björn; Hofmann, Diana; Burauel, Peter

2012-01-01

Soil drying and rewetting may alter the release and availability of aged pesticide residues in soils. A laboratory experiment was conducted to evaluate the influence of soil drying and wetting on the release of pesticide residues. Soil containing environmentally long-term aged (9–17 years) 14C-labeled residues of the herbicides ethidimuron (ETD) and methabenzthiazuron (MBT) and the fungicide anilazine (ANI) showed a significantly higher release of 14C activity in water extracts of previously dried soil compared to constantly moistened soil throughout all samples (ETD: p < 0.1, MBT and ANI: p < 0.01). The extracted 14C activity accounted for 44% (ETD), 15% (MBT), and 20% (ANI) of total residual 14C activity in the samples after 20 successive dry–wet cycles, in contrast to 15% (ETD), 5% (MBT), and 6% (ANI) in extracts of constantly moistened soils. In the dry–wet soils, the dissolved organic carbon (DOC) content correlated with the measured 14C activity in the aqueous liquids and indicated a potential association of DOC with the pesticide molecules. Liquid chromatography MS/MS analyses of the water extracts of dry–wet soils revealed ETD and MBT in detectable amounts, accounting for 1.83 and 0.01%, respectively, of total applied water-extractable parent compound per soil layer. These findings demonstrate a potential remobilization of environmentally aged pesticide residue fractions from soils due to abiotic stresses such as wet–dry cycles. Environ. Toxicol. Chem. 2012; 31: 1941–1947. © 2012 SETAC PMID:22782855

Changes in the enzymatic activity of soil samples upon their storage

NASA Astrophysics Data System (ADS)

Dadenko, E. V.; Kazeev, K. Sh.; Kolesnikov, S. I.; Val'Kov, V. F.

2009-12-01

The influence of the duration and conditions of storage of soil samples on the activity of soil enzymes (catalase, β-fructofuranosidase, and dehydrogenase) was studied for the main soils of southern Russia (different subtypes of chernozems, chestnut soils, brown forest soils, gray forest soils, solonetzes, and solonchaks). The following soil storage conditions were tested: (1) the air-dry state at room temperature, (2) the airdry state at a low positive (in a refrigerator, +4°C) temperature, (3) naturally moist samples at a low positive temperature, and (4) naturally moist samples at a negative (in a freezer, -5°C) temperature. It was found that the sample storing caused significant changes in the enzymatic activities, which depended on the soil type, the land use, the type of enzyme, and the duration and conditions of the sample storage. In the course of the storage, the changes in the enzymatic activity had a nonlinear character. The maximum changes were observed in the initial period (up to 12 weeks). Then, a very gradual decrease in the activity of the studied enzymes was observed. Upon the long-term (>12 weeks) storage under the different conditions, the difference in the activities of the soil enzymes became less pronounced. The storage of soil samples in the air-dried state at room temperature can be recommended for mass investigations.

Soil sorption of organic vapors and effects of humidity on sorptive mechanism and capacity

USGS Publications Warehouse

Chiou, C.T.; Shoup, T.D.

1985-01-01

Vapor sorption isotherms on dry Woodburn soil at 20-30??C were determined for benzene, chlorobenzene, p-dichlorobenzene, m-dichlorobenzene, 1,2,4-trichlorobenzene, and water as single vapors and for benzene, m-dichlorobenzene, and 1,2,4-trichlorobenzene as functions of relative humidity (RH). Isotherms for all compounds on dry soil samples are distinctively nonlinear, with water showing the greatest capacity. Water vapor sharply reduced the sorption capacities of organic compounds with the dry soil; on water-saturated soil, the reduction was about 2 orders of magnitude. The markedly higher sorption of organic vapors at subsaturation humidities is attributed to adsorption on the mineral matter, which predominates over the simultaneous uptake by partition into the organic matter. At about 90% RH, the sorption capacities of organic compounds become comparable to those in aqueous systems. The effect of humidity is attributed to adsorptive displacement by water of organics adsorbed on the mineral matter. A small residual uptake is attributed to the partition into the soil-organic phase that has been postulated in aqueous systems. The results are essentially in keeping with the model that was previously proposed for sorption on the soil from water and from organic solvents.Vapor sorption isotherms on dry Woodburn soil at 20-30 degree C were determined for benzene, chlorobenzene, p-dichlorobenzene, m-dichlorobenzene, 1,2,4-trichlorobenzene, and water as single vapors and for benzene, m-dichlorobenzene, and 1,2,4-trichlorobenzene as functions of relative humidity (RH). Isotherms for all compounds on dry soil samples are distinctively nonlinear, with water showing the greatest capacity. Water vapor sharply reduced the sorption capacities of organic compounds with the dry soil; on water-saturated soil, the reduction was about 2 orders of magnitude. The markedly higher sorption of organic vapors at subsaturation humidities is attributed to adsorption on the mineral matter. The results are essentially in keeping with the model that was previously proposed for sorption on the soil from water and from organic solvents.

Colloid Mobilization in a Fractured Soil during Dry-Wet Cycles: Role of Drying Duration and Flow Path Permeability.

PubMed

Mohanty, Sanjay K; Saiers, James E; Ryan, Joseph N

2015-08-04

In subsurface soils, colloids are mobilized by infiltrating rainwater, but the source of colloids and the process by which colloids are generated between rainfalls are not clear. We examined the effect of drying duration and the spatial variation of soil permeability on the mobilization of in situ colloids in intact soil cores (fractured and heavily weathered saprolite) during dry-wet cycles. Measuring water flux at multiple sampling ports at the core base, we found that water drained through flow paths of different permeability. The duration of antecedent drying cycles affected the amount of mobilized colloids, particularly in high-flux ports that received water from soil regions with a large number of macro- and mesopores. In these ports, the amount of mobilized colloids increased with increased drying duration up to 2.5 days. For drying durations greater than 2.5 days, the amount of mobilized colloids decreased. In contrast, increasing drying duration had a limited effect on colloid mobilization in low-flux ports, which presumably received water from soil regions with fewer macro- and mesopores. On the basis of these results, we attribute this dependence of colloid mobilization upon drying duration to colloid generation from dry pore walls and distribution of colloids in flow paths, which appear to be sensitive to the moisture content of soil after drying and flow path permeability. The results are useful for improving the understanding of colloid mobilization during fluctuating weather conditions.

Persistence of culturable Escherichia coli fecal contaminants in dairy alpine grassland soils.

PubMed

Texier, Stéphanie; Prigent-Combaret, Claire; Gourdon, Marie Hélène; Poirier, Marie Andrée; Faivre, Pierre; Dorioz, Jean Marcel; Poulenard, Jérome; Jocteur-Monrozier, Lucile; Moënne-Loccoz, Yvan; Trevisan, Dominique

2008-01-01

Our knowledge of Escherichia coli (E. coli) ecology in the field is very limited in the case of dairy alpine grassland soils. Here, our objective was to monitor field survival of E. coli in cow pats and underlying soils in four different alpine pasture units, and to determine whether the soil could constitute an environmental reservoir. E. coli was enumerated by MPN using a selective medium. E. coli survived well in cow pats (10(7) to 10(8) cells g(-1) dry pat), but cow pats disappeared within about 2 mo. In each pasture unit, constant levels of E. coli (10(3) to 10(4) cells g(-1) dry soil) were recovered from all topsoil (0-5 cm) samples regardless of the sampling date, that is, under the snow cover, immediately after snow melting, or during the pasture season (during and after the decomposition of pats). In deeper soil layers below the root zone (5-25 cm), E. coli persistence varied according to soil type, with higher numbers recovered in poorly-drained soils (10(3) to 10(4) cells g(-1) dry soil) than in well-drained soils (< 10(2) cells g(-1) dry soil). A preliminary analysis of 38 partial uidA sequences of E. coli from pat and soils highlighted a cluster containing sequences only found in this work. Overall, this study raises the possibility that fecal E. coli could have formed a naturalized (sub)population, which is now part of the indigenous soil community of alpine pasture grasslands, the soil thus representing an environmental reservoir of E. coli.

The influence of land use on the abundance and diversity of ammonia oxidizers.

PubMed

Zhao, Dayong; Luo, Juan; Wang, Jianqun; Huang, Rui; Guo, Kun; Li, Yi; Wu, Qinglong L

2015-02-01

Nitrification plays a significant role in soil nitrogen cycling, a process in which the first step can be catalyzed by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). In this study, six soil samples with distinct land-use regimes (forestland soil, paddy soil, wheat-planted soil, fruit-planted soil, grassland soil, and rape-planted soil) were collected from Chuzhou city in the Anhui province to elucidate the effects of land use on the abundance and diversity of AOA and AOB. The abundance of the archaeal amoA gene ranged from 2.12 × 10(4) copies per gram of dry soil to 2.57 × 10(5) copies per gram of dry soil, while the abundance of the bacterial amoA gene ranged from 5.58 × 10(4) copies per gram of dry soil to 1.59 × 10(8) copies per gram of dry soil. The grassland and the rape-planted soil samples maintained the highest abundance of the bacterial and archaeal amoA genes, respectively. The abundance of the archaeal amoA gene was positively correlated with the pH (P < 0.05). The ammonia concentrations exhibited a significantly positive relation with the abundance of the bacterial amoA gene (P < 0.01) and the number of OTUs of AOB (P < 0.05). The community composition of AOB was more sensitive to the land-use regimes than that of AOA. The data obtained in this study may be useful to better understand the nitrification process in soils with different land-use regimes.

Research on the Optimum Water Content of Detecting Soil Nitrogen Using Near Infrared Sensor

PubMed Central

He, Yong; Nie, Pengcheng; Dong, Tao; Qu, Fangfang; Lin, Lei

2017-01-01

Nitrogen is one of the important indexes to evaluate the physiological and biochemical properties of soil. The level of soil nitrogen content influences the nutrient levels of crops directly. The near infrared sensor can be used to detect the soil nitrogen content rapidly, nondestructively, and conveniently. In order to investigate the effect of the different soil water content on soil nitrogen detection by near infrared sensor, the soil samples were dealt with different drying times and the corresponding water content was measured. The drying time was set from 1 h to 8 h, and every 1 h 90 samples (each nitrogen concentration of 10 samples) were detected. The spectral information of samples was obtained by near infrared sensor, meanwhile, the soil water content was calculated every 1 h. The prediction model of soil nitrogen content was established by two linear modeling methods, including partial least squares (PLS) and uninformative variable elimination (UVE). The experiment shows that the soil has the highest detection accuracy when the drying time is 3 h and the corresponding soil water content is 1.03%. The correlation coefficients of the calibration set are 0.9721 and 0.9656, and the correlation coefficients of the prediction set are 0.9712 and 0.9682, respectively. The prediction accuracy of both models is high, while the prediction effect of PLS model is better and more stable. The results indicate that the soil water content at 1.03% has the minimum influence on the detection of soil nitrogen content using a near infrared sensor while the detection accuracy is the highest and the time cost is the lowest, which is of great significance to develop a portable apparatus detecting nitrogen in the field accurately and rapidly. PMID:28880202

Research on the Optimum Water Content of Detecting Soil Nitrogen Using Near Infrared Sensor.

PubMed

He, Yong; Xiao, Shupei; Nie, Pengcheng; Dong, Tao; Qu, Fangfang; Lin, Lei

2017-09-07

Nitrogen is one of the important indexes to evaluate the physiological and biochemical properties of soil. The level of soil nitrogen content influences the nutrient levels of crops directly. The near infrared sensor can be used to detect the soil nitrogen content rapidly, nondestructively, and conveniently. In order to investigate the effect of the different soil water content on soil nitrogen detection by near infrared sensor, the soil samples were dealt with different drying times and the corresponding water content was measured. The drying time was set from 1 h to 8 h, and every 1 h 90 samples (each nitrogen concentration of 10 samples) were detected. The spectral information of samples was obtained by near infrared sensor, meanwhile, the soil water content was calculated every 1 h. The prediction model of soil nitrogen content was established by two linear modeling methods, including partial least squares (PLS) and uninformative variable elimination (UVE). The experiment shows that the soil has the highest detection accuracy when the drying time is 3 h and the corresponding soil water content is 1.03%. The correlation coefficients of the calibration set are 0.9721 and 0.9656, and the correlation coefficients of the prediction set are 0.9712 and 0.9682, respectively. The prediction accuracy of both models is high, while the prediction effect of PLS model is better and more stable. The results indicate that the soil water content at 1.03% has the minimum influence on the detection of soil nitrogen content using a near infrared sensor while the detection accuracy is the highest and the time cost is the lowest, which is of great significance to develop a portable apparatus detecting nitrogen in the field accurately and rapidly.

Concentration of (137)Cs in soil across Nebraska.

PubMed

Weesner, Alexandra Palensky; Fairchild, Robert W

2008-06-01

Atmospheric nuclear weapons testing from 1945 through 1980 produced radioactive fallout that was transported by stratospheric winds and deposited unevenly around the world. The accident at Chernobyl in 1986 also contributed to the fallout in some locations. The (137)Cs activity concentration from fallout has been measured as a function of depth in soil samples from five different locations across Nebraska. Soil samples 2-cm thick down to a depth of 30 cm were collected in Brown, Dawes, Lancaster, Red Willow, and Thurston Counties. Samples taken from each of the sites were dried, sieved, and counted using an HPGe gamma spectroscopy system to measure the activity concentration of (137)Cs at each depth in the soil. Activity concentrations as high as 216 Bq kg(-1) were measured in the samples. Dry soil bulk densities were calculated for each site based on soil type and used to calculate the area density of deposition. Area deposition densities up to 13,100 Bq m(-2) were measured, consistent with published estimates.

Laboratory and Airborne BRDF Analysis of Vegetation Leaves and Soil Samples

NASA Technical Reports Server (NTRS)

Georgiev, Georgi T.; Gatebe, Charles K.; Butler, James J.; King, Michael D.

2008-01-01

Laboratory-based Bidirectional Reflectance Distribution Function (BRDF) analysis of vegetation leaves, soil, and leaf litter samples is presented. The leaf litter and soil samples, numbered 1 and 2, were obtained from a site located in the savanna biome of South Africa (Skukuza: 25.0degS, 31.5degE). A third soil sample, number 3, was obtained from Etosha Pan, Namibia (19.20degS, 15.93degE, alt. 1100 m). In addition, BRDF of local fresh and dry leaves from tulip tree (Liriodendron tulipifera) and acacia tree (Acacia greggii) were studied. It is shown how the BRDF depends on the incident and scatter angles, sample size (i.e. crushed versus whole leaf,) soil samples fraction size, sample status (i.e. fresh versus dry leaves), vegetation species (poplar versus acacia), and vegetation s biochemical composition. As a demonstration of the application of the results of this study, airborne BRDF measurements acquired with NASA's Cloud Absorption Radiometer (CAR) over the same general site where the soil and leaf litter samples were obtained are compared to the laboratory results. Good agreement between laboratory and airborne measured BRDF is reported.

Aspergillus and Penicillium (Eurotiales: Trichocomaceae) in soils of the Brazilian tropical dry forest: diversity in an area of environmental preservation.

PubMed

Barbosa, Renan do Nascimento; Bezerra, Jadson Diogo Pereira; Costa, Phelipe Manoel Oller; de Lima-Júnior, Nelson Correia; Alves de Souza Galvão, Ivana Roberta Gomes; Alves dos Santos-Júnior, Anthony; Fernandes, Maria José; de Souza-Motta, Cristina Maria; Oliveira, Neiva Tinti

2016-03-01

Soil is a complex biological system that plays a key role for plants and animals, especially in dry forests such as the Caatinga. Fungi from soils, such as Aspergillus and Penicillium, can be used as bioindica- tors for biodiversity conservation. The aim of this study was to isolate and identify species of Aspergillus and Penicillium in soil, from the municipalities of Tupanatinga and Ibimirim, with dry forests, in the Catimbau National Park. Five collections were performed in each area during the drought season of 2012, totaling 25 soil samples per area. Fungi were isolated by suspending soil samples in sterile distilled water and plating on Sabouraud Agar media plus Chloramphenicol and Rose Bengal, and Glycerol Dicloran Agar. Isolates were identified by morphological taxonomy in the Culture Collection Laboratory and confirmed by sequencing of the Internal Transcribed Spacer of rDNA. A total of 42 species were identified, of which 22 belong to the genus Aspergillus and 20 to Penicillium. Penicillium isolates showed uniform distribution from the collecting area in Tupanatinga, and the evenness indices found were 0.92 and 0.88 in Tupanatinga and Ibimirim, respectively. Among isolates of Aspergillus evenness, the value found in Tupanatinga (0.85) was very close to that found in Ibimirim (0.86). High diversity and low dominance of fungi in soil samples was observed. These results con- tributed to the estimation of fungal diversity in dry environments of the Caatinga, where diversity is decreasing in soils that have undergone disturbance.

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

NASA Technical Reports Server (NTRS)

Reyes, A. L.; Campbell, J. E.

1975-01-01

Dry heat treatment is specified as the preferred means for the terminal sterilization of spacecraft and for decontamination of spacecraft components. The presence of organisms highly resistant to dry heat in soil and fallout around assembly and industrial manufacturing areas is shown. The dry heat survival characteristics of the Cape Kennedy isolate 4-6 B. brevis spores is demonstrated. The presence of hardy organisms from soil samples obtained from geographical areas of the United States is shown. A resistant fraction appears to occur in low numbers in a soil sample. The heat resistance characteristics of 4-6 B. brevis and B. subtilis var. niger spores are compared. Their morphological characteristics are compared by scanning electron microscopy.

Microbial mediated soil structure formation under wetting and drying cycles along a climate gradient (arid to humid) on hillslopes in Chile

NASA Astrophysics Data System (ADS)

Bernhard, Nadine; Moskwa, Lisa-Marie; Kühn, Peter; Mueller, Carsten W.; Wagner, Dirk; Scholten, Thomas

2017-04-01

It is well-known that the land surface resistance against erosion is largely controlled by the structure stability of the soil given by its inherent properties. Microbial activity plays a vital role in soil structure development, and thus affecting soil physical parameters. Accordingly the influence of biota shaping the earth's surface has been described through mechanisms such as mineral weathering, formation of ions and biofilms controlling land surface resistance against erosion. However the role of microorganisms for the development of soil stabilizing properties is still unclear and a precise quantitative understanding of the mechanisms under different climate conditions is widely missing. The objectives of our study are to examine to which extend microbiological processes control soil structure formation and stability and whether this is influenced by climate and topographic position. Soil samples were taken along a climate gradient and from different topographic positions of hillslopes in the Chilean Coastal Cordillera in austral autumn 2016. The variables of lithology, human disturbances and relief were held as far as possible constant whereas climate varies along the transect. We implemented 10 wet-dry cycles on air dried and sieved natural and sterile samples to enhance particle aggregation and increase structure stability. Throughout the entire experiment temperature is held constant at 20 °C to avoid changes in microbial activity. Samples are moistened and dried and each kept at the same respective pF-values for the same duration to add the same stress to each sample. Aggregate stability will be measured using wet sieving, ultrasonic dispersion and simulated rainfall. The results will be compared with on-site rainfall simulation experiments on hillslopes in the Chilean Coastal Cordillera to link laboratory results with natural field conditions. The experiment gives first insight into the aggregate formation process over time with and without microorganisms (sterilized samples). Furthermore it allows to qualify and quantify the contribution of biota to soil structure formation and stability.

Effects of drying-wetting and freezing-thawing cycle on leachability of metallic elements in mine soils

NASA Astrophysics Data System (ADS)

Bang, H.; Kim, J.; Hyun, S.

2016-12-01

Mine leachate derived from contaminated mine sites with metallic elements can pose serious risks on human society and environment. Only labile fraction of metallic elements in mine soils is subject to leaching and movement by rainfall. Lability of metallic element in soil is a function of bond strengths between metal and soil surfaces, which is influenced by environmental condition (e.g., rainfall intensity, duration, temperature, etc.) The purpose of this study was to elucidate the effects of various climate conditions on the leaching patterns and lability of metallic elements in mine soils. To do this, two mine soils were sampled from two abandoned mine sites located in Korea. Leaching test were conducted using batch decant-refill method. Various climatic conditions were employed in leaching test such as (1) oven drying (40oC) - wetting cycles, (2) air drying (20oC) - wetting cycle, and (3) freezing (-40oC) - thawing cycles. Duration of drying and freezing were varied from 4 days to 2 weeks. Concentration of metallic elements, pH, Eh and concentration of dissolved iron and sulfate in leachate from each leaching process was measured. To identify the changes of labile fraction in mine soils after each of drying or freezing period, sequential extraction procedure (five fraction) was used to compare labile fraction (i.e., F1 + F2) of metallic elements. The concentration of metallic elements in mine leachate was increased after drying and freezing procedure. The amounts of released metallic element from mine soils was changed depending on their drying or freezing period. In addition, labile fraction of metallic elements in soil was also changed after drying and freezing. The changes in labile fraction after drying and freezing might be due to the increased soil surface area by pore water volume expansion. Further study is therefore needed to evaluate the impact of altered physical properties of soils such as hydration of soil surface area and shrinking by drying and freezing cycles.

Solubility of aluminum and silica in Spodic horizons as affected by drying and freezing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simonsson, M.; Berggren, D.; Gustafsson, J.P.

The release of toxic Al{sup 3+} is one of the most serious consequences of anthropogenic soil acidification. Therefore, the mechanisms controlling Al solubility have been a topic of intense research for more than a decade. For convenience, soil samples are often dried before storage and experimental use. However, the literature offers examples of drying that results in changes in pH, solubility of organic matter, and dissolution rates of Al. In this study, the authors examined the solubility of Al and Si in fresh soil and in soil that had been dried or deep-frozen. Five Spodosol B horizon soils were subjectedmore » to batch titrations, where portions of each soil were equilibrated with solutions with varying concentrations of acid or base added. Extractions with acid oxalate and Na pyrophosphate indicated the presence of imogolite-type materials (ITM) in three of the soils. In the other two soils most secondary solid-phase Al was associated with humic substances. Deep-freezing did not significantly change pH nor the concentration of Al or Si as compared with fresh soil. Drying, on the other hand, yielded pH increases of up to 0.3 units at a given addition of acid or base, whereas Al{sup 3+} changed only slightly, implying a higher Al solubility in all of the soils. Furthermore, dissolved silica increased by up to 200% after drying, except in a soil that almost completely lacked oxalate-extractable Si. The authors suggest that drying enhanced the dissolution of ITM by disrupting soil organic matter, thus exposing formerly coated mineral surfaces. In the soil where dissolved Si did not change with drying, it has been demonstrated that Al-humus complexes controlled Al solubility. They suggest that fissures in the organic material caused by drying may have exposed formerly occluded binding sites that had a higher Al saturation than had sites at the surface of humus particles.« less

Spatial and temporal variation of moisture content in the soil profiles of two different agricultural fields of semi-arid region.

PubMed

Baskan, Oguz; Kosker, Yakup; Erpul, Gunay

2013-12-01

Modeling spatio-temporal variation of soil moisture with depth in the soil profile plays an important role for semi-arid crop production from an agro-hydrological perspective. This study was performed in Guvenc Catchment. Two soil series that were called Tabyabayir (TaS) and Kervanpinari (KeS) and classified as Leptosol and Vertisol Soil Groups were used in this research. The TeS has a much shallower (0-34 cm) than the KeS (0-134 cm). At every sampling time, a total of geo-referenced 100 soil moisture samples were taken based on horizon depths. The results indicated that soil moisture content changed spatially and temporally with soil texture and profile depth significantly. In addition, land use was to be important factor when soil was shallow. When the soil conditions were towards to dry, higher values for the coefficient of variation (CV) were observed for TaS (58 and 43% for A and C horizons, respectively); however, the profile CV values were rather stable at the KeS. Spatial variability range of TaS was always higher at both dry and wet soil conditions when compared to that of KeS. Excessive drying of soil prevented to describe any spatial model for surface horizon, additionally resulting in a high nugget variance in the subsurface horizon for the TaS. On the contrary to TaS, distribution maps were formed all horizons for the KeS at any measurement times. These maps, depicting both dry and wet soil conditions through the profile depth, are highly expected to reduce the uncertainty associated with spatially and temporally determining the hydraulic responses of the catchment soils.

Soil-to-crop transfer factors of tellurium.

PubMed

Yang, Guosheng; Zheng, Jian; Tagami, Keiko; Uchida, Shigeo

2014-09-01

Stable tellurium (Te) concentrations in 148 sets of agricultural soil and associated crop samples were measured in this study to obtain soil-to-crop transfer factor (TF) of Te. We used a recently developed simple method that applies digestion of samples with aqua regia and sector field inductively coupled plasma mass spectrometry to measure low Te levels in these samples. Geometric mean (GM) concentrations of Te in soil and crops were 75μgkg(-1)-dry (range: 15-850μgkg(-1)-dry) and 1.8μgkg(-1)-dry (range: 0.1-120μgkg(-1)-dry), respectively; the Te concentration range was significantly wider in crops than in soil. Using these data, we calculated TFs and obtained their range from 1.3×10(-3) to 1.1×10(-1). The GM of TF for upland field crops was calculated to be 2.0×10(-2) and for brown rice was 3.1×10(-2); all crop types had the similar GMs of their TF values. Data comparison for TF of Te was carried out with six elements, which are present in anionic forms in soil environment like Te is, i.e. P, Br, As, Se, Mo, and I. TFs of Te and I showed the highest correlation factor for upland field crops by t-test (r=0.577, p<0.001), but no correlation was found for brown rice. We considered it likely that different water management practices in upland fields and paddy fields affected the Te transfer from soil to crops. Copyright © 2014 Elsevier Ltd. All rights reserved.

GEMAS: Colours of dry and moist agricultural soil samples of Europe

NASA Astrophysics Data System (ADS)

Klug, Martin; Fabian, Karl; Reimann, Clemens

2016-04-01

High resolution HDR colour images of all Ap samples from the GEMAS survey were acquired using a GeoTek Linescan camera. Three measurements of dry and wet samples with increasing exposure time and increasing illumination settings produced a set of colour images at 50μm resolution. Automated image processing was used to calibrate the six images per sample with respect to the synchronously measured X-Rite colorchecker chart. The calibrated images were then fit to Munsell soil colours that were measured in the same way. The results provide overview maps of dry and moist European soil colours. Because colour is closely linked to iron mineralogy, carbonate, silicate and organic carbon content the results can be correlated to magnetic, mineralogical, and geochemical properties. In combination with the full GEMAS chemical and physical measurements, this yields a valuable data set for calibration and interpretation of visible satellite colour data with respect to chemical composition and geological background, soil moisture, and soil degradation. This data set will help to develop new methods for world-wide characterization and monitoring of agricultural soils which is essential for quantifying geologic and human impact on the critical zone environment. It furthermore enables the scientific community and governmental authorities to monitor consequences of climatic change, to plan and administrate economic and ecological land use, and to use the data set for forensic applications.

The impact of extreme environmental factors on the mineralization potential of the soil

NASA Astrophysics Data System (ADS)

Zinyakova, Natalia; Semenov, Vyacheslav

2016-04-01

Warming, drying, wetting are the prevalent disturbing natural impacts that affect the upper layers of uncultivated and arable soils. The effect of drying-wetting cycles act as a physiological stress for the soil microbial community and cause changes in its structure, the partial death or lysis of the microbial biomass. The mobilization of the SOM and the stabilization of the potentially mineralizable components lead to change of mineralization potential in the soil. To test the effects of different moisture regime on plant growth and soil biological properties, plot experiment with the gray forest soil including trials with plants (corn) and bare fallow was performed. Different regimes of soil moisture (conditionally optimal, relatively deficient soil moisture and repeated cycles of drying-wetting) were created. Control of soil moisture was taken every two or three days. Gas sampling was carried out using closed chambers. Soil samples were collected at the end of the pot experiment. The potentially mineralizable content of soil organic carbon (SOC) was measured by biokinetic method based on (1) aerobic incubation of soil samples under constant temperature and moisture conditions during 158 days, (2) quantitation of C-CO2, and (3) fitting of C-CO2 cumulative curve by a model of first-order kinetic. Total soil organic carbon was measured by Tyrin's wet chemical oxidation method. Permanent deficient moisture in the soil favored the preservation of potentially mineralizable SOC. Two repeated cycles of drying-wetting did not reduce the potentially mineralizable carbon content in comparison with control under optimal soil moisture during 90 days of experiment. The emission loss of C-CO2 from the soil with plants was 1.4-1.7 times higher than the decrease of potentially mineralizable SOC due to the contribution of root respiration. On the contrary, the decrease of potentially mineralized SOC in the soil without plants was 1.1-1.2 times larger than C-CO2 emissions from the soil as a result of stabilization processes. Thus, the alternation of drying-wetting cycles results in 1) the death of microbial biomass and recolonization of the soil microorganisms; 2) favors the splitting and degradation of soil aggregates, as well as the reaggregation and stabilization of aggregates; 3) contributes to the mobilization of the SOM and also 4) initiates the stabilization of the potentially mineralizable components. The effect of drying-wetting cycles is expressed not so much in the loss of the total soil organic carbon as in the degradation of the SOM quality with decreasing its mineralization potential. We can conclude that different soil moisture regimes lead to essential changes of mineralization potential in the gray forest soil. The amount of mineralization loss soil carbon via C-CO2 emission is directly associated with the decrease of potentially mineralizable carbon. Deficient moisture is a reason for temporarily sequestration of SOC potentially mineralizable under optimal moisture. This work was supported by RSF. Project number 14-14-00625

Copepod (Crustacea) emergence from soils from everglades marshes with different hydroperiods

USGS Publications Warehouse

Loftus, W.F.; Reid, J.W.

2000-01-01

During a severe drought period in the winter and spring of 1989, we made three collections of dried marsh soils from freshwater sloughs in Everglades National Park, Florida, at sites characterized by either long or intermediate annual periods of flooding (hydroperiod). After rehydrating the soils in aquaria, we documented the temporal patterns of copepod emergence over two-week periods. The species richness of copepods in the rehydrated soils was lower than in pre-drought samples from the same slough sites. Only six of the 16 species recorded from the Everglades emerged in the aquarium tests. The long hydroperiod site had a slightly different assemblage and higher numbers of most species than the intermediate-hydroperiod sites. More individuals and species emerged from the early dry-season samples compared with samples taken later in the dry season. The harpacticoid, Cletocamptus deitersi, and the cyclopoid, Microcyclops rubellus, were abundant at most sites. The cyclopoids - Ectocyclops phaleratus, Homocyclops ater, and Paracyclops chiltoni - are new records for the Everglades. We infer that 1) only a subset of Everglades copepod species can survive drought by resting in soils; and that 2) survival ability over time differs by species.

Gamma-Ray Attenuation to Evaluate Soil Porosity: An Analysis of Methods

PubMed Central

Pires, Luiz F.; Pereira, André B.

2014-01-01

Soil porosity (ϕ) is of a great deal for environmental studies due to the fact that water infiltrates and suffers redistribution in the soil pore space. Many physical and biochemical processes related to environmental quality occur in the soil porous system. Representative determinations of ϕ are necessary due to the importance of this physical property in several fields of natural sciences. In the current work, two methods to evaluate ϕ were analyzed by means of gamma-ray attenuation technique. The first method uses the soil attenuation approach through dry soil and saturated samples, whereas the second one utilizes the same approach but taking into account dry soil samples to assess soil bulk density and soil particle density to determine ϕ. The results obtained point out a good correlation between both methods. However, when ϕ is obtained through soil water content at saturation and a 4 mm collimator is used to collimate the gamma-ray beam the first method also shows good correlations with the traditional one. PMID:24616640

Determination of the water retention of peat soils in the range of the permanent wilting point.

NASA Astrophysics Data System (ADS)

Nünning, Lena; Bechtold, Michel; Dettmann, Ullrich; Piayda, Arndt; Tiemeyer, Bärbel; Durner, Wolfgang

2017-04-01

Global coverage of peatlands decreases due to the use of peat for horticulture and to the drainage of peatlands for agriculture and forestry. While alternatives for peat in horticulture exist, profitable agriculture on peatlands and climate protection are far more difficult to combine. A controlled water management that is optimized to stabilize yields while reducing peat degradation provides a promising path in this direction. For this goal, profound knowledge of hydraulic properties of organic soil is essential, for which, however, literature is scarce. This study aimed to compare different methods to determine the water retention of organic soils in the dry range (pF 3 to 4.5). Three common methods were compared: two pressure based apparatus (ceramic plate vs. membrane, Eijkelkamp) and a dew point potentiameter (WP4C, Decagon Devices), which is based on the equilibrium of soil water potential and air humidity. Two different types of organic soil samples were analyzed: i) samples wet from the field and ii) samples that were rewetted after oven-drying. Additional WP4C measurements were performed at samples from standard evaporation experiments directly after they have been finished. Results were: 1) no systematic differences between pressure apparatus and WP4C measurements, 2) however, high moisture variability of the samples from the pressure apparatus as well as high variability of the WP4C measurements at these samples when they were removed from these devices which indicated that applied pressure did not establish well in all samples, 3) rewetted oven-dried samples resulted in up to three times lower soil moistures even after long equilibrium times, i.e. there was a strong and long-lasting hysteresis effect that was highest for less degraded peat samples, 4) and highly consistent WP4C measurements at samples from the end of the evaporation experiment. Results provide useful information for deriving reliable water retention characteristics for organic soils.

Chemical characterization and spatial distribution of PAHs and heavy hydrocarbons in rural sites of Campania Region, South Italy.

PubMed

Monaco, D; Riccio, A; Chianese, E; Adamo, P; Di Rosa, S; Fagnano, M

2015-10-01

In this paper, the behaviour and distribution patterns of heavy hydrocarbons and several polycyclic aromatic hydrocarbon (PAH) priority pollutants, as listed by the US Environmental Protection Agency, were evaluated in 891 soil samples. The samples were collected in three expected polluted rural sites in Campania (southern Italy) as part of the LIFE11 ECOREMED project, funded by the European Commission, to test innovative agriculture-based soil restoration techniques. These sites have been selected because they have been used for the temporary storage of urban and building waste (Teverola), subject to illicit dumping of unknown material (Trentola-Ducenta), or suspected to be polluted by metals due to agricultural practices (Giugliano). Chemical analysis of soil samples allowed the baseline pollution levels to be determined prior to any intervention. It was found that these areas can be considered contaminated for residential use, in accordance with Italian environmental law (Law Decree 152/2006). Statistical analysis applied to the data proved that average mean concentrations of heavy hydrocarbons could be as high as 140 mg/kg of dry soil with peaks of 700 mg/kg of dry soil, for the Trentola-Ducenta site; the median concentration of analytical results for hydrocarbon (HC) concentration for the Trentola-Ducenta and Giugliano sites was 63 and 73.4 mg/kg dry soil, respectively; for Teverola, the median level was 35 mg/kg dry soil. Some PAHs (usually benzo(a)pyrene) also exceeded the maximum allowed level in all sites. From the principal component analysis applied to PAH concentrations, it emerged that pollutants can be supposed to derive from a single source for the three sites. Diagnostic ratios calculated to determine possible PAH sources suggest petroleum combustion or disposal practice. Our sampling protocol also showed large dishomogeneity in soil pollutant spatial distribution, even at a scale as small as 3.3 m, indicating that variability could emerge at very short spatial scales.

Ecotoxicological study of arsenic and lead contaminated soils in former orchards at the Hanford Site, USA.

PubMed

Delistraty, Damon; Yokel, Jerry

2014-01-01

The purpose of this study was to assess ecotoxicity of former orchard soils contaminated with lead arsenate pesticides at the Hanford Site in Washington state (USA). Surface soil, plant, and invertebrate samples were collected from 11 sites in former orchard areas. Mean (standard deviation [SD]) for As and Pb in soil were 39.5 (40.6) and 208 (142) mg/kg dry wt, respectively (n = 11). These concentrations exceeded Hanford background levels but were similar to orchard soils elsewhere. In our study, As and Pb soil concentrations were positively and significantly correlated (r = 0.87, Bonferroni P < 0.05). Speciation of total inorganic As in soil (n = 6) demonstrated that As+5 was the dominant form (>99%). Mean (SD) for As and Pb in cheatgrass were 3.9 (7.9) and 12.4 (20.0) mg/kg dry wt, respectively (n = 11), while mean (SD) for As and Pb in darkling beetles were 5.4 (2.6) and 3.9 (3.0) mg/kg dry wt, respectively (n = 8). Linear regressions were constructed to estimate soil to cheatgrass and soil to darkling beetle uptake for As and Pb. These were significant (Bonferroni P < 0.05) only for cheatgrass versus soil (As) and darkling beetle versus soil (Pb). Standardized lettuce seedling and earthworm bioassays were performed with a subset of soil samples (n = 6). No significant effects (P > 0.05) were observed in lettuce survival or growth nor in earthworm survival or sublethal effects. Based on these bioassays, unbounded no observed effect concentrations (NOECs) in soil for As and Pb were 128 and 390 mg/kg dry wt, respectively. However, our range of soil concentrations generally overlapped a set of ecotoxicological benchmarks reported in the literature. Given uncertainty and limited sampling related to our NOECs, as well as uncertainty in generic benchmarks from the literature, further study is needed to refine characterization of As and Pb ecotoxicity in former orchard soils at the Hanford Site. Copyright © 2011 Wiley Periodicals, Inc.

Influence of soil conditions on dissolved organic matter leached from forest and wetland soils: a controlled growth chamber study.

PubMed

Kim, Eun-Ah; Nguyen, Hang Vo-Minh; Oh, Hae Sung; Hur, Jin; Choi, Jung Hyun

2016-03-01

This study investigated the effects of various soil conditions, including drying-rewetting, nitrogen deposition, and temperature rise, on the quantities and the composition of dissolved organic matter leached from forest and wetland soils. A set of forest and wetland soils with and without the nitrogen deposition were incubated in the growth chambers under three different temperatures. The moisture contents were kept constant, except for two-week drying intervals. Comparisons between the original and the treated samples revealed that drying-rewetting was a crucial environmental factor driving changes in the amount of dissolved organic carbon (DOC). The DOC was also notably increased by the nitrogen deposition to the dry forest soil and was affected by the temperature of the dry wetland soil. A parallel factor (PARAFAC) analysis identified three sub-fractions of the fluorescent dissolved organic matter (FDOM) from the fluorescence excitation-emission matrices (EEMs), and their compositions depended on drying-rewetting. The data as a whole, including the DOC and PARAFAC components and other optical indices, were possibly explained by the two main variables, which were closely related with the PARAFAC components and DOC based on principal component analysis (PCA). Our results suggested that the DOC and PARAFAC component information could provide a comprehensive interpretation of the changes in the soil-leached DOM in response to the different environmental conditions.

[Impact of periodical flooding-drying on nitrification and ammonia oxidizers in hydro-fluctuation belt of the Three Gorges Reservoir].

PubMed

Guo, Jia; Jiang, Xianjun; Zhou, Xue; Meng, Yao; Jia, Zhongjun

2016-06-04

This study was aimed to elucidate the effect of periodic flooding-drying to ecological processes of ammonia oxidizers in the hydro-fluctuation belt of the Three Gorges Reservoir. Soil samples were collected at thee altitudes in regions of Wanzhou, Fengdu and Changshou, representing 8, 5 and 0 times floodingdrying management, respectively. Soil physiochemical properties were analyzed and microcosms were constructed to monitor nitrification activity by fertilizing soils with ammonium substrate. Real-time PCR was used to quantify the population size of ammonia-oxidizing archaea (AOA) and bacteria (AOB). DGGE fingerprints and clone libraries were conducted to study the shift of AOA and AOB compositions in nitrifying soils. Among the physiochemical characteristics of the soils, soil organic matter and total phosphates increased along with cycle increasing. After incubation for 13 days, the net nitrification rates of the samples with 8 cycles exceeded those with 5 cycles. The quantities of both AOA and AOB have increased during the incubation. Phylogenetic analysis showed that AOA were placed within the soil group 1.1b and soil group 1.1a, while bacterial ammonia oxidizers were closely related to Nitrosospira and Cluster 0. Periodical flooding-drying increased soil organic matter, enhanced soil nitrification activity and likely played important roles in shaping community structures of soil ammonia oxidizers.

Plants as sources of airborne bacteria, including ice nucleation-active bacteria.

PubMed

Lindemann, J; Constantinidou, H A; Barchet, W R; Upper, C D

1982-11-01

Vertical wind shear and concentration gradients of viable, airborne bacteria were used to calculate the upward flux of viable cells above bare soil and canopies of several crops. Concentrations at soil or canopy height varied from 46 colony-forming units per m over young corn and wet soil to 663 colony-forming units per m over dry soil and 6,500 colony-forming units per m over a closed wheat canopy. In simultaneous samples, concentrations of viable bacteria in the air 10 m inside an alfalfa field were fourfold higher than those over a field with dry, bare soil immediately upwind. The upward flux of viable bacteria over alfalfa was three- to fourfold greater than over dry soil. Concentrations of ice nucleation-active bacteria were higher over plants than over soil. Thus, plant canopies may constitute a major source of bacteria, including ice nucleation-active bacteria, in the air.

Responses of soil ammonia oxidizers to a short-term severe mercury stress.

PubMed

Zhou, Zhi-Feng; Liu, Yu-Rong; Sun, Guo-Xin; Zheng, Yuan-Ming

2015-12-01

The responses of soil ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) to mercury (Hg) stress were investigated through a short-term incubation experiment. Treated with four different concentrations of Hg (CK, Hg25, Hg50, and Hg100, denoting 0, 25, 50, and 100mgHg/kg dry soil, respectively), samples were harvested after 3, 7, and 28day incubation. Results showed that the soil potential nitrification rate (PNR) was significantly inhibited by Hg stress during the incubation. However, lower abundances of AOA (the highest in CK: 9.20×10(7)copies/g dry soil; the lowest in Hg50: 2.68×10(7)copies/g dry soil) and AOB (the highest in CK: 2.68×10(7)copies/g dry soil; the lowest in Hg50: 7.49×10(6)copies/g dry soil) were observed only at day 28 of incubation (P<0.05). Moreover, only the community structure of soil AOB obviously shifted under Hg stress as seen through DGGE profiles, which revealed that 2-3 distinct AOB bands emerged in the Hg treatments at day 28. In summary, soil PNR might be a very useful parameter to assess acute Hg stress on soil ecosystems, and the community structure of soil AOB might be a realistic biological indicator for the assessment of heavy metal stress on soil ecosystems in the future. Copyright © 2015. Published by Elsevier B.V.

Soil profile property estimation with field and laboratory VNIR spectroscopy

USDA-ARS?s Scientific Manuscript database

Diffuse reflectance spectroscopy (DRS) soil sensors have the potential to provide rapid, high-resolution estimation of multiple soil properties. Although many studies have focused on laboratory-based visible and near-infrared (VNIR) spectroscopy of dried soil samples, previous work has demonstrated ...

State-Space Estimation of Soil Organic Carbon Stock

NASA Astrophysics Data System (ADS)

Ogunwole, Joshua O.; Timm, Luis C.; Obidike-Ugwu, Evelyn O.; Gabriels, Donald M.

2014-04-01

Understanding soil spatial variability and identifying soil parameters most determinant to soil organic carbon stock is pivotal to precision in ecological modelling, prediction, estimation and management of soil within a landscape. This study investigates and describes field soil variability and its structural pattern for agricultural management decisions. The main aim was to relate variation in soil organic carbon stock to soil properties and to estimate soil organic carbon stock from the soil properties. A transect sampling of 100 points at 3 m intervals was carried out. Soils were sampled and analyzed for soil organic carbon and other selected soil properties along with determination of dry aggregate and water-stable aggregate fractions. Principal component analysis, geostatistics, and state-space analysis were conducted on the analyzed soil properties. The first three principal components explained 53.2% of the total variation; Principal Component 1 was dominated by soil exchange complex and dry sieved macroaggregates clusters. Exponential semivariogram model described the structure of soil organic carbon stock with a strong dependence indicating that soil organic carbon values were correlated up to 10.8m.Neighbouring values of soil organic carbon stock, all waterstable aggregate fractions, and dithionite and pyrophosphate iron gave reliable estimate of soil organic carbon stock by state-space.

Bioassay of plant growth from soils varying in active C and N fractions

USDA-ARS?s Scientific Manuscript database

Biologically active soil C and N fractions are important attributes of healthy soil. As a bioassay, we hypothesized that active soil C and N fractions would relate with plant dry matter production from unamended soil. Four replicate soil samples from 22 tall fescue fields in North Carolina and Virgi...

An estimation of the main wetting branch of the soil water retention curve based on its main drying branch using the machine learning method

NASA Astrophysics Data System (ADS)

Lamorski, Krzysztof; Šimūnek, Jiří; Sławiński, Cezary; Lamorska, Joanna

2017-02-01

In this paper, we estimated using the machine learning methodology the main wetting branch of the soil water retention curve based on the knowledge of the main drying branch and other, optional, basic soil characteristics (particle size distribution, bulk density, organic matter content, or soil specific surface). The support vector machine algorithm was used for the models' development. The data needed by this algorithm for model training and validation consisted of 104 different undisturbed soil core samples collected from the topsoil layer (A horizon) of different soil profiles in Poland. The main wetting and drying branches of SWRC, as well as other basic soil physical characteristics, were determined for all soil samples. Models relying on different sets of input parameters were developed and validated. The analysis showed that taking into account other input parameters (i.e., particle size distribution, bulk density, organic matter content, or soil specific surface) than information about the drying branch of the SWRC has essentially no impact on the models' estimations. Developed models are validated and compared with well-known models that can be used for the same purpose, such as the Mualem (1977) (M77) and Kool and Parker (1987) (KP87) models. The developed models estimate the main wetting SWRC branch with estimation errors (RMSE = 0.018 m3/m3) that are significantly lower than those for the M77 (RMSE = 0.025 m3/m3) or KP87 (RMSE = 0. 047 m3/m3) models.

Dielectric constants of soils at microwave frequencies

NASA Technical Reports Server (NTRS)

Geiger, F. E.; Williams, D.

1972-01-01

A knowledge of the complex dielectric constant of soils is essential in the interpretation of microwave airborne radiometer data of the earth's surface. Measurements were made at 37 GHz on various soils from the Phoenix, Ariz., area. Extensive data have been obtained for dry soil and soil with water content in the range from 0.6 to 35 percent by dry weight. Measurements were made in a two arm microwave bridge and results were corrected for reflections at the sample interfaces by solution of the parallel dielectric plate problem. The maximum dielectric constants are about a factor of 3 lower than those reported for similar soils at X-band frequencies.

The Effect of Drying-Wetting Cycle’s Repetition to the Characteristic of Natural and Stabilization Residual Soils Jawa Timur - Indonesia

NASA Astrophysics Data System (ADS)

Muntaha, M.

2017-11-01

Indonesia, which located in tropical region, continuously undergoes wetting and drying cycles due to the changeable seasons. An important role in activating the clay minerals on tropical residual soils is the main factor that affects the static and dynamic properties, such as: volume change, soil suction and dynamic modulus. The purpose of this paper is to evaluate the effect of drying-wetting cycles repetition on volume change, soil suction and mechanical characteristics of natural and stabilization of residual soils from Jawa Timur - Indonesia. The natural undisturbed and stabilized residual soil sample was naturally and gradually dried up with air to 25%, 50%, 75%, and 100 % of the initial water content. The wetting processes were carried out with the gradual increment water content of 25 %(wsat - wi), 50 %(wsat - wi), 75 %(wsat - wi), up to 100 %(wsat - wi). The Direct Shear test is used to measure the mechanic properties, and Whatman filter paper No. 42 is used to measure the soil suction. The drying-wetting processes were carried out for 1, 2, 4, and 6 cycles. The laboratory test results showed that, the void ratio decreased, the unit weight, cohesion and the internal friction angle were increasing due to stabilization. Drying-wetting cycle repetition reduces void ratio, negative pore-water pressure, cohesion and internal friction angle of natural and stabilized soils. Briefly, the decreased of mechanical soil properties was proven from the physical properties change observation.

Survival of rhizobia in two soils as influenced by storage conditions.

PubMed

Martyniuk, Stefan; Oroń, Jadwiga

2008-01-01

Two soils were kept moist at 4 degrees C, -20 degrees C or air-dried at 20-22 degrees C and after one week, one month, two months and six months of storage at these conditions changes in soil populations of Rhizobium leguminosarum bv. trifolii (Rlt) and Rhizobium leguminosarum bv. viciae (Rlv) were examined. In one air-dried soil (from Grab6w) markedly lower numbers of both Rlt and Rlv., as compared to the refrigerated or frozen samples, were found already after 1 week of storage. In the case of the second soil (from Osiny) air-drying significantly reduced numbers of the rhizobia after 2 and 6 months of storage. The soil from Osiny contained higher amounts of C org, total N and clay than the Grabów soil. Both soils stored moist in a refrigerator (4 degrees C) or frozen (-20 degrees C) retained similar populations of the examined rhizobia throughout the entire storage period, indicating that soil freezing is not detrimental for the examined rhizobia.

Rapid identification of oil-contaminated soils using visible near-infrared diffuse reflectance spectroscopy.

PubMed

Chakraborty, Somsubhra; Weindorf, David C; Morgan, Cristine L S; Ge, Yufeng; Galbraith, John M; Li, Bin; Kahlon, Charanjit S

2010-01-01

In the United States, petroleum extraction, refinement, and transportation present countless opportunities for spillage mishaps. A method for rapid field appraisal and mapping of petroleum hydrocarbon-contaminated soils for environmental cleanup purposes would be useful. Visible near-infrared (VisNIR, 350-2500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, nondestructive, proximal-sensing technique that has proven adept at quantifying soil properties in situ. The objective of this study was to determine the prediction accuracy of VisNIR DRS in quantifying petroleum hydrocarbons in contaminated soils. Forty-six soil samples (including both contaminated and reference samples) were collected from six different parishes in Louisiana. Each soil sample was scanned using VisNIR DRS at three combinations of moisture content and pretreatment: (i) field-moist intact aggregates, (ii) air-dried intact aggregates, (iii) and air-dried ground soil (sieved through a 2-mm sieve). The VisNIR spectra of soil samples were used to predict total petroleum hydrocarbon (TPH) content in the soil using partial least squares (PLS) regression and boosted regression tree (BRT) models. Each model was validated with 30% of the samples that were randomly selected and not used in the calibration model. The field-moist intact scan proved best for predicting TPH content with a validation r2 of 0.64 and relative percent difference (RPD) of 1.70. Because VisNIR DRS was promising for rapidly predicting soil petroleum hydrocarbon content, future research is warranted to evaluate the methodology for identifying petroleum contaminated soils.

Estimation of soil profile properties using field and laboratory VNIR spectroscopy

USDA-ARS?s Scientific Manuscript database

Diffuse reflectance spectroscopy (DRS) soil sensors have the potential to provide rapid, high-resolution estimation of multiple soil properties. Although many studies have focused on laboratory-based visible and near-infrared (VNIR) spectroscopy of dried soil samples, previous work has demonstrated ...

Visible-near infrared spectroscopy as a tool to improve mapping of soil properties

NASA Astrophysics Data System (ADS)

Evgrafova, Alevtina; Kühnel, Anna; Bogner, Christina; Haase, Ina; Shibistova, Olga; Guggenberger, Georg; Tananaev, Nikita; Sauheitl, Leopold; Spielvogel, Sandra

2017-04-01

Spectroscopic measurements, which are non-destructive, precise and rapid, can be used to predict soil properties and help estimate the spatial variability of soil properties at the pedon scale. These estimations are required for quantifying soil properties with higher precision, identifying the changes in soil properties and ecosystem response to climate change as well as increasing the estimation accuracy of soil-related models. Our objectives were to (i) predict soil properties for nested samples (n = 296) using the laboratory-based visible-near infrared (vis-NIR) spectra of air-dried (<2 mm) soil samples and values of measured soil properties for gridded samples (n = 174) as calibration and validation sets; (ii) estimate the precision and predictive accuracy of an empirical spectral model using (a) our own spectral library and (b) the global spectral library; (iii) support the global spectral library with obtained vis-NIR spectral data on permafrost-affected soils. The soil samples were collected from three permafrost-affected soil profiles underlain by permafrost at various depths between 23 cm to 57.5 cm below the surface (Cryosols) and one soil profile with no presence of permafrost within the upper 100 cm layer (Cambisol) in order to characterize the spatial distribution and variability of soil properties. The gridded soil samples (n = 174) were collected using an 80 cm wide grid with a mesh size of 10 cm on both axes. In addition, 300 nested soil samples were collected using a grid of 12 cm by 12 cm (25 samples per grid) from a hole of 1 cm in a diameter with a distance from the next sample of 1 cm. Due to a small amount of available soil material (< 1.5 g), 296 nested soil samples were analyzed only using vis-NIR spectroscopy. The air-dried mineral gridded soil samples (n = 174) were sieved through a 2-mm sieve and ground with an agate mortar prior to the elemental analysis. The soil organic carbon and total nitrogen concentrations (in %) were determined using a dry combustion method on the Vario EL cube analyzer (Elementar Analysensysteme GmbH, Germany). Inorganic C was removed from the mineral soil samples with pH values higher than 7 prior to the elemental analysis using the volatilization method (HCl, 6 hours). The pH of soil samples was measured in 0.01 M CaCl2 using a 1:2 soil:solution ratio. However, for soil sample with a high in organic matter content, a 1:10 ratio was applied. We also measured oxalate and dithionite extracted iron, aluminum and manganese oxides and hydroxides using inductively coupled plasma optical emission spectroscopy (Varian Vista MPX ICP-OES, Agilent Technologies, USA). We predicted the above-mentioned soil properties for all nested samples using partial least squares regression, which was performed using R program. We can conclude that vis-NIR spectroscopy can be used effectively in order to describe, estimate and further map the spatial patterns of soil properties using geostatistical methods. This research could also help to improve the global soil spectral library taking into account that only few previous applications of vis-NIR spectroscopy were conducted on permafrost-affected soils of Northern Siberia. Keywords: Visible-near infrared spectroscopy, vis-NIR, permafrost-affected soils, Siberia, partial least squares regression.

A study of psychrophilic organisms isolated from the manufacture and assembly areas of spacecraft to be used in the Viking mission

NASA Technical Reports Server (NTRS)

Foster, T. L.

1974-01-01

The effect of storage of dry heat treated Teflon ribbons under nitrogen gas followed by high vacuum on the recovery of hardy organisms from the ribbons was studied. A similar experiment was performed on spore crops of hardy organisms recovered previously from Cape Canaveral. Hardy organisms have been inoculated onto slides and subjected to an artificial Martian environment in an attempt to demonstrate their growth in this environment. Additional experiments using the artificial Martian environment include response of soil samples from the VAB with both constant temperature and freeze-thaw cycles. These experiments were performed with dried soil and soil containing added water. Other investigations included the effect of heatshock on soil samples, psychrophilic counts of new soil samples from the manufacture area of the Viking spacecraft, effect of pour plate versus spread plate on psychrophilic counts, and preparation of spore crops of hardy organisms from Cape Canaveral.

Comparison of organochlorine pesticides and polychlorinated biphenyls residues in vegetables, grain and soil from organic and conventional farming in Poland.

PubMed

Witczak, Agata; Abdel-Gawad, Hassan

2012-01-01

Organic and conventional crops were studied by identifying the relationship between persistent organic pollutants in cereals, vegetables and soil. The residues of organochlorine pesticides and polychlorinated biphenyls (PCBs) were determined in grains (rye and wheat), vegetables (carrots and beets) and soil collected from the fields. PCB residues recorded in the beets from organic farming were as high as 3.71 ppb dry weight (dry wt.), while in the soil from conventional farming of beets 0.53 ppb dry wt. Among vegetables, higher concentrations of pesticides were detected in organically grown beets (190.63 ppb dry wt.). Soil samples from the organic farming contained lower levels of organochlorine pesticide residues compared to the conventional farming. Taking into account toxicity equivalent (TEQ), the conventionally grown carrots accumulated the most toxic PCBs. Non-ortho and mono-ortho PCBs were also noted in the grain of conventionally grown rye and amounted to 3.05 pg-TEQ/g wet wt.

Soil developments in polar deserts: Implications for exobiology and future Mars missions

NASA Technical Reports Server (NTRS)

Gibson, Everett K., Jr.

1989-01-01

Chemical alterations, weathering, and diagenesis of soil profiles from the dry valleys of Antarctica were studied as analogs of regolith development for the Martian regolith. Chemical weathering processes play an important part in soil development within the dry valleys of Antarctica. A suite of core samples were studied which were taken within the valley floors in addition to samples taken in the vicinity of evaporite and brine ponds. Analysis of water soluable cations and anions from core samples were performed along with petrographic analysis of selected samples. It was shown that ionic transport processes operate primarily above the permafrost zone. Abundances of the water soluable ions reflect the nature of secondary minerals produced by evaporation and weathering. Chloride, calcium, and sodium abundances for soils from the cores within the North and South Forks of Wright Valley, reflect the secondary mineralogy of the soil columns. Calculations for Na, Ca, and Cl abundances reflect the appearance of halite and antarcticite. In areas where excess Ca is present, X-ray diffraction studies show the presence of gypsum. It is well known that the Martian surface conditions may be favorable for chemical weathering. Primary silicates would be expected to be reactive with any ground water. It seems likely that Martian subsurface water is available to assist in the weathering of the primary minerals. Such weathering could result in the formation of clays, sulfates, carbonates, hydrates, halides, and zeolites. The dry valley cores have shown that they maybe excellent analogs to weathering processes on the near-surface of Mars. Since movement of water within the near-surface region clearly results in chemical weathering, leaching, and salt formation in the dry valleys, similar processes are probably operating within the Martian regolith.

Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area.

PubMed

Bozlaker, Ayse; Odabasi, Mustafa; Muezzinoglu, Aysen

2008-12-01

Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle+gas) Sigma(41)-PCB concentrations were higher in summer (3370+/-1617 pg m(-3), average+SD) than in winter (1164+/-618 pg m(-3)), probably due to increased volatilization with temperature. Average particulate Sigma(41)-PCBs dry deposition fluxes were 349+/-183 and 469+/-328 ng m(-2) day(-1) in summer and winter, respectively. Overall average particulate deposition velocity was 5.5+/-3.5 cm s(-1). The spatial distribution of Sigma(41)-PCB soil concentrations (n=48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.

Stable Isotope Analysis of Water Indicates that Mixing Occurs between Mobile and Tightly-Bound Soil Water

NASA Astrophysics Data System (ADS)

Vargas, A. I.; Schaffer, B.; Yuhong, L.; Sternberg, L. O.

2016-12-01

Stable oxygen (δ18O) and hydrogen (δ2H) isotope composition of precipitation, soil and plants have been studied over the years to understand the mechanism of soil water movement and the depth of plant water uptake in the soil water profile. Recent studies have suggested that in soil during the wet season, tightly bound water does not mix with mobile water but is retained in the soil until the dry season when it is taken up by plants via the force of transpiration. To test this, we sampled δ18O and δ2H in plant stems as a proxy for wet season mobile water and dry season bound water in two types of soils to determine if mixing occurs between mobile and tightly bound soil water. Plastic pots were filled with clay or very gravelly loam soil and a Persea americana tree was planted in each pot. Soil in each pot was first saturated with tap water to fully label the bound water with the isotopic identity of tap water and then fully saturated with either tap water (T) or isotopically-enriched pool water (P) and covered with white polyethylene to prevent evaporation. After saturating the soil, δ18O and δ2H of water draining from each pot were similar to those of water added to each pot for both the T and P treatments. For each treatment, δ18O and δ2H in plant stems were sampled 2-3 days after soil was initially saturated (simulated wet season; soil tension < 0.10 kPa) representing the mobile water and again 7-9 days after soil was saturated representing the bound water (simulated dry season; soil tension > 80.0 kPa). During the "dry season", there was a significant difference between T and P treatments for δ18O and δ2H in plant stems, indicating that bound water accessed by plants in the P treatment did not retain the tap water label and mixing occurred between mobile and bound water in the soil. Comparing P-T in the wet season with P-T in the dry season indicated that as much as 95% of water freely exchanged between the mobile and bound components of the soil. This is contrary to recent studies suggesting that no mixing occurs.

ESEM results and changes in wettability patterns within soil: three years irrigation with slightly-salted water

NASA Astrophysics Data System (ADS)

Valdes-Abellan, Javier; Candela, Lucila; Medero, Gabriela; Buckman, Jim; Hasnayn, Mohammad M.

2015-04-01

Impacts on soil and aquifer media from the use of non-conventional water (treated wastewater-TWW, desalted) for irrigation have been widely studied in the last years . A number of contributions have focused on the impacts derived from the use of TWW (Assouline and Narkis, 2013; Lahav et al., 2010; Xu et al., 2010). Changes in soil hydraulic conductivity and clogging processes have been studied in laboratory experiments from soil columns (Lado and Ben-Hur, 2010) and at field scale (Costa, 1999; Minhas et al., 1994). Irrigation with non-conventional water may also lead to the occurrence of contaminants, a major current environmental concern (Valdes-Abellan et al., 2013). Previous studies have considered impacts in a uniform soil media pore structure; less attention has been paid at a microscopic scale and the influence that high-salinity water may have on wettability of soil. Environmental scanning electron microscopy (ESEM) is a useful technique to be applied in soil science to analyse microscopic changes in soil structure or soil wetting patterns. Research applying this technology for wet systems (Donald, 1998) or porous media (Ali et al., 1995) is available, however as far as we know research on soil impacts due to long term irrigation with saline or non-conventional water are much less common. The dynamic mode of the ESEM allows changes of samples from wet to dry by modifying the water vapour pressure and to observe the wetting and drying patterns and interactions between the solid and liquid phase in the soil (Lourenço et al., 2008). Preliminary results of the study at a microscopic scale of soil samples collected before and after three year irrigation with slightly salted water in an experimental plot setup in semi-arid climatic conditions (Alicante, SE Spain) are presented. We will show the micro-structure of soil and undertake a preliminary investigation of wetting and drying of samples using ESEM techniques Differences in the water vapour pressure value at which complete saturation is achieved was detected, being lower in the 3-years irrigated samples compared with the initial ones. Besides, velocity in which saturation took place was different: initial samples saturation process were developed very quickly, as triggered by a critical shift in the water vapour pressure value and much gradual process were develop in the 3-years irrigated sample when saturation started earlier.

Occurrence of Acanthamoeba genotypes in Central West Malaysian environments.

PubMed

Basher, Mohamad Hafiz Abdul; Ithoi, Init; Mahmud, Rohela; Abdulsalam, Awatif Mohamed; Foead, Agus Iwan; Dawaki, Salwa; Atroosh, Wahib Mohammed Mohsen; Nissapatorn, Veeranoot; Abdullah, Wan Omar

2018-02-01

Acanthamoeba species are ubiquitous free-living protozoa that can be found worldwide. Occasionally, it can become parasitic and the causative agent of acanthamoebic keratitis (AK) and Granulomatous Amoebic Encephalitis (GAE) in man. A total of 160 environmental samples and 225 naturally-infected animal corneal swabs were collected for Acanthamoeba cultivation. Acanthamoeba was found to be high in samples collected from environments (85%, 136/160) compared to infected animal corneas (24.89%, 56/225) by microscopic examination. Analysis of nucleotide sequence of 18S rRNA gene of all the 192 cultivable Acanthamoeba isolates revealed 4 genotypes (T3, T4. T5 and T15) with T4 as the most prevalent (69.27%, 133/192) followed by T5 (20.31%), T15 (9.90%) and T3 (0.52%). Genotype T4 was from the strain of A. castellanii U07401 (44.27%), A. castellanii U07409 (20.83%) and A. polyphagaAY026243 (4.17%), but interestingly, only A. castellanii U07401 was detected in naturally infected corneal samples. In environmental samples, T4 was commonly detected in all samples including dry soil, dust, wet debris, wet soil and water. Among the T4, A. castellanii (U07409) strains were detected high occurrence in dry (45%) followed by aquatic (32.50%) and moist (22.50%) samples but however A. castellanii (U07401) strains were dominant in dry samples of soil and dust (93.10%). Subsequently, genotype T5 of A. lenticulata (U94741) strains were dominant in samples collected from aquatic environments (58.97%). In summary, A. castellanii (U07401) strains were found dominant in both environmental and corneal swab samples. Therefore, these strains are possibly the most virulent and dry soil or dusts are the most possible source of Acanthamoeba infection in cats and dogs corneas. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of Mercury Contamination in Fungi Boletus Species from Latosols, Lateritic Red Earths, and Red and Yellow Earths in the Circum-Pacific Mercuriferous Belt of Southwestern China.

PubMed

Falandysz, Jerzy; Zhang, Ji; Wang, Yuan-Zhong; Saba, Martyna; Krasińska, Grażyna; Wiejak, Anna; Li, Tao

2015-01-01

For the first time, highly elevated levels of mercury (Hg) have been documented for several species of the edible Fungi genus Boletus growing in latosols, lateritic red earths, and red and yellow earths from the Yunnan province of China. Analysis of Hg concentrations in the genus suggests that geogenic Hg is the dominant source of Hg in the fungi, whereas anthropogenic sources accumulate largely in the organic layer of the forest soil horizon. Among the 21 species studied from 32 locations across Yunnan and 2 places in Sichuan Province, the Hg was found at elevated level in all samples from Yunnan but not in the samples from Sichuan, which is located outside the mercuriferous belt. Particularly abundant in Hg were the caps of fruiting bodies of Boletus aereus (up to 13 mg kg-1 dry matter), Boletus bicolor (up to 5.5 mg kg-1 dry matter), Boletus edulis (up to 22 mg kg-1 dry matter), Boletus luridus (up to 11 mg kg-1 dry matter), Boletus magnificus (up to 13 mg kg-1 dry matter), Boletus obscureumbrinus (up to 9.4 mg kg-1 dry matter), Boletus purpureus (up to 16 mg kg-1 dry matter), Boletus sinicus (up to 6.8 mg kg-1 dry matter), Boletus speciosus (up to 4.9mg kg-1 dry matter), Boletus tomentipes (up to 13 mg kg-1 dry matter), and Boletus umbriniporus (up to 4.9 mg kg-1 dry matter). Soil samples of the 0-10 cm topsoil layer from the widely distributed locations had mercury levels ranging between 0.034 to 3.4 mg kg-1 dry matter. In Yunnan, both the soil parent rock and fruiting bodies of Boletus spp. were enriched in Hg, whereas the same species from Sichuan, located outside the mercuriferous belt, had low Hg concentrations, suggesting that the Hg in the Yunnan samples is mainly from geogenic sources rather than anthropogenic sources. However, the contribution of anthropogenically-derived Hg sequestered within soils of Yunnan has not been quantified, so more future research is required. Our results suggest that high rates of consumption of Boletus spp. from Yunnan can deliver relatively high doses of Hg to consumers, but that rates can differ widely because of large variability in mercury concentrations between species and locations.

Evaluation of Mercury Contamination in Fungi Boletus Species from Latosols, Lateritic Red Earths, and Red and Yellow Earths in the Circum-Pacific Mercuriferous Belt of Southwestern China

PubMed Central

Falandysz, Jerzy; Zhang, Ji; Wang, Yuan-Zhong; Saba, Martyna; Krasińska, Grażyna; Wiejak, Anna; Li, Tao

2015-01-01

For the first time, highly elevated levels of mercury (Hg) have been documented for several species of the edible Fungi genus Boletus growing in latosols, lateritic red earths, and red and yellow earths from the Yunnan province of China. Analysis of Hg concentrations in the genus suggests that geogenic Hg is the dominant source of Hg in the fungi, whereas anthropogenic sources accumulate largely in the organic layer of the forest soil horizon. Among the 21 species studied from 32 locations across Yunnan and 2 places in Sichuan Province, the Hg was found at elevated level in all samples from Yunnan but not in the samples from Sichuan, which is located outside the mercuriferous belt. Particularly abundant in Hg were the caps of fruiting bodies of Boletus aereus (up to 13 mg kg-1 dry matter), Boletus bicolor (up to 5.5 mg kg-1 dry matter), Boletus edulis (up to 22 mg kg-1 dry matter), Boletus luridus (up to 11 mg kg-1 dry matter), Boletus magnificus (up to 13 mg kg-1 dry matter), Boletus obscureumbrinus (up to 9.4 mg kg-1 dry matter), Boletus purpureus (up to 16 mg kg-1 dry matter), Boletus sinicus (up to 6.8 mg kg-1 dry matter), Boletus speciosus (up to 4.9mg kg-1 dry matter), Boletus tomentipes (up to 13 mg kg-1 dry matter), and Boletus umbriniporus (up to 4.9 mg kg-1 dry matter). Soil samples of the 0–10 cm topsoil layer from the widely distributed locations had mercury levels ranging between 0.034 to 3.4 mg kg-1 dry matter. In Yunnan, both the soil parent rock and fruiting bodies of Boletus spp. were enriched in Hg, whereas the same species from Sichuan, located outside the mercuriferous belt, had low Hg concentrations, suggesting that the Hg in the Yunnan samples is mainly from geogenic sources rather than anthropogenic sources. However, the contribution of anthropogenically-derived Hg sequestered within soils of Yunnan has not been quantified, so more future research is required. Our results suggest that high rates of consumption of Boletus spp. from Yunnan can deliver relatively high doses of Hg to consumers, but that rates can differ widely because of large variability in mercury concentrations between species and locations. PMID:26606425

The Inter-Valley Soil Comparative Survey: the ecology of Dry Valley edaphic microbial communities

PubMed Central

Lee, Charles K; Barbier, Béatrice A; Bottos, Eric M; McDonald, Ian R; Cary, Stephen Craig

2012-01-01

Recent applications of molecular genetics to edaphic microbial communities of the McMurdo Dry Valleys and elsewhere have rejected a long-held belief that Antarctic soils contain extremely limited microbial diversity. The Inter-Valley Soil Comparative Survey aims to elucidate the factors shaping these unique microbial communities and their biogeography by integrating molecular genetic approaches with biogeochemical analyses. Although the microbial communities of Dry Valley soils may be complex, there is little doubt that the ecosystem's food web is relatively simple, and evidence suggests that physicochemical conditions may have the dominant role in shaping microbial communities. To examine this hypothesis, bacterial communities from representative soil samples collected in four geographically disparate Dry Valleys were analyzed using molecular genetic tools, including pyrosequencing of 16S rRNA gene PCR amplicons. Results show that the four communities are structurally and phylogenetically distinct, and possess significantly different levels of diversity. Strikingly, only 2 of 214 phylotypes were found in all four valleys, challenging a widespread assumption that the microbiota of the Dry Valleys is composed of a few cosmopolitan species. Analysis of soil geochemical properties indicated that salt content, alongside altitude and Cu2+, was significantly correlated with differences in microbial communities. Our results indicate that the microbial ecology of Dry Valley soils is highly localized and that physicochemical factors potentially have major roles in shaping the microbiology of ice-free areas of Antarctica. These findings hint at links between Dry Valley glacial geomorphology and microbial ecology, and raise previously unrecognized issues related to environmental management of this unique ecosystem. PMID:22170424

Wet-dry cycles impact DOM retention in subsurface soils

NASA Astrophysics Data System (ADS)

Olshansky, Yaniv; Root, Robert A.; Chorover, Jon

2018-02-01

Transport and reactivity of carbon in the critical zone are highly controlled by reactions of dissolved organic matter (DOM) with subsurface soils, including adsorption, transformation and exchange. These reactions are dependent on frequent wet-dry cycles common to the unsaturated zone, particularly in semi-arid regions. To test for an effect of wet-dry cycles on DOM interaction and stabilization in subsoils, samples were collected from subsurface (Bw) horizons of an Entisol and an Alfisol from the Catalina-Jemez Critical Zone Observatory and sequentially reacted (four batch steps) with DOM extracted from the corresponding soil litter layers. Between each reaction step, soils either were allowed to air dry (wet-dry treatment) before introduction of the following DOM solution or were maintained under constant wetness (continually wet treatment). Microbial degradation was the dominant mechanism of DOM loss from solution for the Entisol subsoil, which had higher initial organic C content, whereas sorptive retention predominated in the lower C Alfisol subsoil. For a given soil, bulk dissolved organic C losses from solution were similar across treatments. However, a combination of Fourier transform infrared (FTIR) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopic analyses revealed that wet-dry treatments enhanced the interactions between carboxyl functional groups and soil particle surfaces. Scanning transmission X-ray microscopy (STXM) data suggested that cation bridging by Ca2+ was the primary mechanism for carboxyl association with soil surfaces. STXM data also showed that spatial fractionation of adsorbed OM on soil organo-mineral surfaces was diminished relative to what might be inferred from previously published observations pertaining to DOM fractionation on reaction with specimen mineral phases. This study provides direct evidence of the role of wet-dry cycles in affecting sorption reactions of DOM to a complex soil matrix. In the soil environment, where wet-dry cycles occur at different frequencies from site to site and along the soil profile, different interactions between DOM and soil surfaces are expected and need to be considered for the overall assessment of carbon dynamics.

Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wild fire

NASA Astrophysics Data System (ADS)

Sun, Q.; Meyer, W. S.; Koerber, G.; Marschner, P.

2015-06-01

Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wild fire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well-known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content which could be further modulated by wild fire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy Mallee woodland, where part of the woodland experienced a wild fire which destroyed or damaged most of the aboveground plant parts four months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80% of maximum water holding capacity for 19 days; In DRW, soils were dried for four days, kept dry for another five days, then rewet to 80% WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per g soil in CM and DRW was greater under trees, but lower when expressed per g TOC. Organic matter content, available P, and microbial biomass C, but not available N were greater under trees than in open areas. Wild fire decreased the flush of respiration per g TOC in the open areas and under shrubs, and reduced TOC and MBC concentrations only under trees, but had little effect on available N and P concentrations. We conclude that of the impact wild fire and DRW events on nutrient cycling differ among vegetation patches of a native semiarid woodland which is related to organic matter amount and availability.

A Citizen Science Soil Moisture Sensor to Support SMAP Calibration/Validation

NASA Astrophysics Data System (ADS)

Podest, E.; Das, N. N.

2016-12-01

The Soil Moisture Active Passive (SMAP) satellite mission was launched in Jan. 2015 and is currently acquiring global measurements of soil moisture in the top 5 cm of the soil every 3 days. SMAP has partnered with the GLOBE program to engage students from around the world to collect in situ soil moisture and help validate SMAP measurements. The current GLOBE SMAP soil moisture protocol consists in collecting a soil sample, weighing, drying and weighing it again in order to determine the amount of water in the soil. Preparation and soil sample collection can take up to 20 minutes and drying can take up to 3 days. We have hence developed a soil moisture measurement device based on Arduino-like microcontrollers along with off-the-shelf and homemade sensors that are accurate, robust, inexpensive and quick and easy to use so that they can be implemented by the GLOBE community and citizen scientists alike. This talk will discuss building, calibration and validation of the soil moisture measuring device and assessing the quality of the measurements collected. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

X-ray microtomography analysis of soil structure deformation caused by centrifugation

NASA Astrophysics Data System (ADS)

Schlüter, Steffen; Leuther, Frederic; Vogler, Steffen; Vogel, Hans-Jörg

2016-04-01

Centrifugation provides a fast method to measure soil water retention curves over a wide moisture range. However, deformation of soil structure may occur at high angular velocities in the centrifuge. The objective of this study was to capture these changes in soil structure with X-ray microtomography and to measure local deformations via digital volume correlation. Two samples were investigated that differ in texture and rock content. A detailed analysis of the pore space reveals an interplay between shrinkage due to drying and soil compaction due to compression. Macroporosity increases at moderate angular velocity because of crack formation due to moisture release. At higher angular velocities, corresponding to capillary pressure of <-100kPa, macroporosity decreases again because of structure deformation due to compression. While volume changes due to swelling clay minerals are immanent to any drying process, the compaction of soil is a specific drawback of the centrifugation method. A new protocol for digital volume correlation was developed to analyze the spatial heterogeneity of deformation. In both samples the displacement of soil constituents is highest in the top part of the sample and exhibits high lateral variability explained by the spatial distribution of macropores in the sample. Centrifugation should therefore only be applied after the completion of all other hydraulic or thermal experiments, or any other analysis that depends on the integrity of soil structure.

X-ray microtomography analysis of soil structure deformation caused by centrifugation

NASA Astrophysics Data System (ADS)

Schlüter, S.; Leuther, F.; Vogler, S.; Vogel, H.-J.

2016-01-01

Centrifugation provides a fast method to measure soil water retention curves over a wide moisture range. However, deformation of soil structure may occur at high angular velocities in the centrifuge. The objective of this study was to capture these changes in soil structure with X-ray microtomography and to measure local deformations via digital volume correlation. Two samples were investigated that differ in texture and rock content. A detailed analysis of the pore space reveals an interplay between shrinkage due to drying and soil compaction due to compression. Macroporosity increases at moderate angular velocity because of crack formation due to moisture release. At higher angular velocities, corresponding to capillary pressure of ψ < -100 kPa, macroporosity decreases again because of structure deformation due to compression. While volume changes due to swelling clay minerals are immanent in any drying process, the compaction of soil is a specific drawback of the centrifugation method. A new protocol for digital volume correlation was developed to analyze the spatial heterogeneity of deformation. In both samples the displacement of soil constituents is highest in the top part of the sample and exhibits high lateral variability explained by the spatial distribution of macropores in the sample. Centrifugation should therefore only be applied after the completion of all other hydraulic or thermal experiments, or any other analysis that depends on the integrity of soil structure.

Depletion of Stem Water of Sclerocarya birrea Agroforestry Tree Precedes Start of Rainy Season in West African Sudanian Zone

NASA Astrophysics Data System (ADS)

Ceperley, Natalie; Mande, Theophile; Parlange, Marc B.

2013-04-01

Understanding water use by agroforestry trees in dry-land ecosystems is essential for improving water management. Agroforestry trees are valued and promoted for many of their ecologic and economic benefits but are often criticized as competing for valuable water resources. In order to understand the seasonal patterns of source water used by agroforestry trees, samples from rain, ground, and surface water were collected weekly in the subcatchment of the Singou watershed that is part of the Volta Basin. Soil and vegetation samples were collected from and under a Sclerocarya birrea agroforstry trees located in this catchment in sealed vials, extracted, and analyzed with a Picarro L2130-i CRDS to obtain both δO18 and δDH fractions. Meteorological measurements were taken with a network of wireless, autonomous stations that communicate through the GSM network (Sensorscope) and two complete eddy-covariance energy balance stations, in addition to intense monitoring of sub-canopy solar radiation, throughfall, stemflow, and soil moisture. Examination of the time series of δO18 concentrations confirm that values in soil and xylem water are coupled, both becoming enriched during the dry season and depleted during the rainy season. Xylem water δO18 levels drops to groundwater δO18 levels in early March when trees access groundwater for leafing out, however soil water does not reach this level until soil moisture increases in mid-June. The relationship between the δDH and δO18 concentrations of water extracted from soil and tree samples do not fall along the global meteoric water line. In order to explore whether this was a seasonally driven, we grouped samples into an "evaporated" group or a "meteoric" group based on the smaller residual to the respective lines. Although more soil samples were found along the m-line during the rainy season than tree samples or dry season soil samples, there was no significant difference in days since rain for any group This suggests that xylem water is always under stress from evapotranspiration and soil water underwent evaporation soon after a rain event. Visual observation of tree confirms conclusion that trees access deep ground water in March and April, before rain begins and before soil is connected to groundwater. Results from the research are being integrated into a local outreach project to improve use of agroforestry.

Distribution of artificial sweeteners in dust and soil in China and their seasonal variations in the environment of Tianjin.

PubMed

Gan, Zhiwei; Sun, Hongwen; Yao, Yiming; Zhao, Yangyang; Li, Yan; Zhang, Yanwei; Hu, Hongwei; Wang, Ruonan

2014-08-01

A nationwide investigation on the occurrence of artificial sweeteners (ASs) was conducted by collecting 98 paired outdoor dust and soil samples from mainland China. The ASs were widely detected in Chinese atmospheric dry deposition and soil samples, at concentrations up to 6450 and 1280 ng/g, respectively. To give a picture on AS distribution and source in the whole environment, the concentrations and seasonal variations of ASs in Tianjin were studied, including atmosphere, soil, and water samples. The AS levels were significantly higher in Haihe river at TJW (a sampling site in central city) in winter, while no obviously seasonal trends were obtained at BYL (close to a AS factory) and the site at a wastewater treatment plant. Saccharin, cyclamate, and acesulfame were the dominant ASs in both gas and particulate phase, with concentrations varying from 0.02 to 1940 pg/m(3). Generally, gas phase concentrations of the ASs were relatively higher in summer, while opposite results were acquired for particulate phase. Wet and dry deposition fluxes were calculated based on the measured AS levels. The results indicated that both wet and dry deposition could efficiently remove ASs in the atmosphere and act as important pollutant sources for the ASs in surface environment. Copyright © 2014 Elsevier B.V. All rights reserved.

[Change in soil enzymes activities after adding biochar or straw by fluorescent microplate method].

PubMed

Zhang, Yu-Lan; Chen, Li-Jun; Duan, Zheng-Hu; Wu, Zhi-Jie; Sun, Cai-Xia; Wang, Jun-Yu

2014-02-01

The present work was aimed to study soil a-glucosidase and beta-glucosidase activities of and red soils based on fluorescence detection method combined with 96 microplates with TECAN Infinite 200 Multi-Mode Microplate Reader. We added biochar or straw (2.5 g air dry sample/50g air dry soil sample) into and red soils and the test was carried under fixed temperature and humidity condition (25 degrees C, 20% soil moisture content). The results showed that straw addition enhances soil alpha-glucosidase and beta-glucosidase activities, beta-glucosidase activity stimulated by rice straw treatment was higher than that of corn straw treatment, and activity still maintains strong after 40 days, accounting for increasing soil carbon transformation with straw inputting. Straw inputting increased soil nutrients contents and may promote microbial activity, which also lead to the increase oin enzyme Straw inputting increased soil nutrients contents and may promote microbial activity, which also lead to the increase oin enzyme activities. Different effects of straw kinds may be related to material source that needs further research. However, biochar inputting has little effect on soil alpha-glucosidase and beta-glucosidase activity. Biochar contains less available nutrients than straw and have degradation-resistant characteristics. Compared with the conventional spectrophotometric method, fluorescence microplate method is more sensitive to soil enzyme activities in suspension liquid, which can be used in a large number of samples. In brief, fluorescence microplate method is fast, accurate, and simple to determine soil enzymes activities.

Amoebae from antarctic soil and water.

PubMed Central

Brown, T J; Cursons, R T; Keys, E A

1982-01-01

Samples of soil and water were taken from the McMurdo Sound-Dry Valley region of Antarctica. Of the 70 samples cultured, 22 yielded amoebae capable of clonal growth at 30 degrees C. None of the isolates was pathogenic for mice. Acanthamoeba isolates appeared to show better survival potential than Naegleria isolates. PMID:7125658

Long-term changes in the chemical composition of soil organic matter, depending on fertilization and crop rotation

NASA Astrophysics Data System (ADS)

Tammik, Kerttu; Kauer, Karin; Astover, Alar

2017-04-01

The objective of this study was to determine whether it is possible to assess the impact of different management practices (crop rotation, fertilization (organic and mineral fertilizers) on the chemical composition of soil organic matter, using Fourier transform infrared spectroscopy (FTIR). The study is based IOSDV long-term (established in 1989) three field crop rotation (potato-wheat-barely) experiment located in Tartu, Estonia. Soil samples (Stagnic Albeluvisol) were collected from the 0-20 cm depth in the autumn of 2015, air dried, sieved to 2 mm and grinded to obtain homogeneous samples. The content of soil organic matter was measured by the dry combustion method in a varioMax CNS elemental analyser (ELEMENTAR, Germany). The samples were analysed using Thermo-Nicolet iS10 Fourier Transform Infrared Spectrophotometer (FT-IR) and OMNIC software. An intense and sharp peak was recorded in the region of Si-O vibrations of clay minerals and polysaccharides in all samples analysed. The volume of the peak correlated with the quantity of fertilizers administered

The Use of a Geographic Information System and Remote Sensing Technology for Monitoring Land Use and Soil Carbon Change in the Subtropical Dry Forest Life Zone of Puerto Rico

NASA Technical Reports Server (NTRS)

Velez-Rodriguez, Linda L. (Principal Investigator)

1996-01-01

Aerial photography, one of the first form of remote sensing technology, has long been an invaluable means to monitor activities and conditions at the Earth's surface. Geographic Information Systems or GIS is the use of computers in showing and manipulating spatial data. This report will present the use of geographic information systems and remote sensing technology for monitoring land use and soil carbon change in the subtropical dry forest life zone of Puerto Rico. This research included the south of Puerto Rico that belongs to the subtropical dry forest life zone. The Guanica Commonwealth Forest Biosphere Reserve and the Jobos Bay National Estuarine Research Reserve are studied in detail, because of their location in the subtropical dry forest life zone. Aerial photography, digital multispectral imagery, soil samples, soil survey maps, field inspections, and differential global positioning system (DGPS) observations were used.

Water uptake depth analyses using stable water isotopes in rice-based cropping systems in Southeastern Asia

NASA Astrophysics Data System (ADS)

Mahindawansha, Amani; Kraft, Philipp; Orlowski, Natalie; Racela, Healthcliff S. U.; Breuer, Lutz

2017-04-01

Rice is one of the most water-consuming crop in the world. Understanding water source utilization of rice-based cropping systems will help to improve water use efficiency (WUE) in paddy management. The objectives of our study were to (1) determine the contributions of various water sources to plant growth in diversified rice-based production systems (wet rice, aerobic rice) (2) investigate water uptake depths at different maturity periods during wet and dry conditions, and (3) calculate WUE of the cropping systems. Our field experiment is based on changes of stable water isotope concentrations in the soil-plant-atmosphere continuum due to transpiration and evaporation. Soil samples were collected together with root sampling from nine different depths under vegetative, reproductive, and matured periods of plant growth together with stem samples. Soil and plant samples were extracted by cryogenic vacuum extraction. Groundwater, surface water, rain, and irrigation water were sampled weekly. All water samples were analyzed for hydrogen and oxygen isotope ratios (δ2H and δ18O) via a laser spectroscope (Los Gatos DLT100). The direct inference approach, which is based on comparing isotopic compositions between plant stem water and soil water, were used to determine water sources taken up by plant. Multiple-source mass balance assessment can provide the estimated range of potential contributions of water from each soil depth to root water uptake of a crop. These estimations were used to determine the proportion of water from upper soil horizons and deep horizons for rice in different maturity periods during wet and dry seasons. Shallow soil water has the higher evaporation than from deeper soil water where the highest evaporation effect is at 5 cm depth (drying front). Water uptake is mostly taking place from surface water in the vegetative and between 5-10 cm in the reproductive period, since roots have grown widely and deeper in the reproductive stage. This will be helpful to understand the WUE and identify the most efficient water management system and the influence of groundwater and surface water during both seasons in rice-based cropping ecosystems by using means of stable water isotope.

Chemical weathering and diagenesis of a cold desert soil from Wright Valley, Antarctica - An analog of Martian weathering processes

NASA Technical Reports Server (NTRS)

Gibson, E. K.; Mckay, D. S.; Wentworth, S. J.

1983-01-01

Weathering, diagenesis, and chemical alteration of a soil profile from the Dry Valleys of Antarctica are investigated as an analog to soil development within the Martian regolith. Soil samples from a soil pit one meter deep on Prospect Mesa, Wright Valley, are examined for their major element concentrations, water-soluble cations and anions, carbon, sulfur, and water concentrations, and related petrographic characteristics of weathering in a cold, dry environment. A petrographic study of the samples suggests that most silicate mineral and lithic fragments exhibit some degree of alteration. Chemical alteration occurs both in samples above and within the permanently frozen zone. The concentrations of water-soluble cations, for example, Na(+), K(+), Ca(2+), and anions, Cl(-), SO4(2-), NO3(-), are found to decrease significantly from the surface to the permanently frozen zone, suggesting a major movement of water-soluble species. It is also found that enrichments in secondary mineral abundances correlate with the water soluble ion concentrations. The formation of zeolites is seen throughout the soil column; these, it is thought, may be reservoirs for volatile storage within the regolith.

Determination of parabens and endocrine-disrupting alkylphenols in soil by gas chromatography-mass spectrometry following matrix solid-phase dispersion or in-column microwave-assisted extraction: a comparative study.

PubMed

Pérez, R A; Albero, B; Miguel, E; Sánchez-Brunete, C

2012-03-01

Two rapid methods were evaluated for the simultaneous extraction of seven parabens and two alkylphenols from soil based on matrix solid-phase dispersion (MSPD) and microwave-assisted extraction (MAE). Soil extracts were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide and analyzed by gas chromatography with mass spectrometry. Extraction and clean-up of samples were carried out by both methods in a single step. A glass sample holder, inside the microwave cell, was used in MAE to allow the simultaneous extraction and clean-up of samples and shorten the MAE procedure. The detection limits achieved by MSPD were lower than those obtained by MAE because the presence of matrix interferences increased with this extraction method. The extraction yields obtained by MSPD and MAE for three different types of soils were compared. Both procedures showed good recoveries and sensitivity for the determination of parabens and alkylphenols in two of the soils assayed, however, only MSPD yielded good recoveries with the other soil. Finally, MSPD was applied to the analysis of soils collected in different sites of Spain. In most of the samples analyzed, methylparaben and butylparaben were detected at levels ranging from 1.21 to 8.04 ng g(-1) dry weight and 0.48 to 1.02 ng g(-1) dry weight, respectively.

Analysis of radiocaesium in the Lebanese soil one decade after the Chernobyl accident.

PubMed

El Samad, O; Zahraman, K; Baydoun, R; Nasreddine, M

2007-01-01

Fallout from the Chernobyl reactor accident due to the transport of a radioactive cloud over Lebanon in the beginning of May 1986 was studied 12 years after the accident for determining the level of (137)Cs concentration in soil. Gamma spectroscopy measurements were performed by using coaxial high sensitivity HPGe detectors. More than 90 soil samples were collected from points uniformly distributed throughout the land of Lebanon in order to evaluate their radioactivity. The data obtained showed a relatively high (137)Cs activity per surface area contamination, up to 6545Bqm(-2) in the top soil layer 0-3cm. The average activity of (137)Cs in the top soil layer 0-3cm in depth was 59.7Bqkg(-1) dry soil ranging from 15 to 119Bqkg(-1) dry soil. The horizontal variability was found to be about 45% between the sampling sites. The depth distribution of total (137)Cs activity in soil showed an exponential decrease. Estimation of the annual effective dose due to external radiation from (137)Cs contaminated soil for selected sites gave values ranging from 19.3 to 91.6 micro Svy(-1).

Land surface energy budget during dry spells: global CMIP5 AMIP simulations vs. satellite observations

NASA Astrophysics Data System (ADS)

Gallego-Elvira, Belen; Taylor, Christopher M.; Harris, Phil P.; Ghent, Darren; Folwell, Sonja S.

2015-04-01

During extended periods without rain (dry spells), the soil can dry out due to vegetation transpiration and soil evaporation. At some point in this drying cycle, land surface conditions change from energy-limited to water-limited evapotranspiration, and this is accompanied by an increase of the ground and overlying air temperatures. Regionally, the characteristics of this transition determine the influence of soil moisture on air temperature and rainfall. Global Climate Models (GCMs) disagree on where and how strongly the surface energy budget is limited by soil moisture. Flux tower observations are improving our understanding of these dry down processes, but typical heterogeneous landscapes are too sparsely sampled to ascertain a representative regional response. Alternatively, satellite observations of land surface temperature (LST) provide indirect information about the surface energy partition at 1km resolution globally. In our study, we analyse how well the dry spell dynamics of LST are represented by GCMs across the globe. We use a spatially and temporally aggregated diagnostic to describe the composite response of LST during surface dry down in rain-free periods in distinct climatic regions. The diagnostic is derived from daytime MODIS-Terra LST observations and bias-corrected meteorological re-analyses, and compared against the outputs of historical climate simulations of seven models running the CMIP5 AMIP experiment. Dry spell events are stratified by antecedent precipitation, land cover type and geographic regions to assess the sensitivity of surface warming rates to soil moisture levels at the onset of a dry spell for different surface and climatic zones. In a number of drought-prone hot spot regions, we find important differences in simulated dry spell behaviour, both between models, and compared to observations. These model biases are likely to compromise seasonal forecasts and future climate projections.

Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying

PubMed Central

Puértolas, Jaime; Conesa, María R.; Ballester, Carlos; Dodd, Ian C.

2015-01-01

Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0–10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm3 cm–3 for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. PMID:25547916

Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying.

PubMed

Puértolas, Jaime; Conesa, María R; Ballester, Carlos; Dodd, Ian C

2015-04-01

Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Baseline soil levels of PCDD/Fs established prior to the construction of municipal solid waste incinerators in China.

PubMed

Liu, Hong-mei; Lu, Sheng-yong; Buekens, Alfons G; Chen, Tong; Li, Xiao-dong; Yan, Jian-hua; Ma, Xiao-jun; Cen, Ke-fa

2012-01-01

In order to determine the baseline contamination by polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in different areas in China, prior to the construction of municipal solid waste incinerators (MSWIs), a total of 32 representative soil samples was collected near 16 incinerators and analyzed for their PCDD/F concentrations. The PCDD/F baseline concentrations in the soil samples ranged from 0.32 to 11.4 ng I-TEQ kg(-1) (dry matter), with average and median value of 2.73 and 2.24 ng I-TEQ kg(-1) (dry matter), respectively, and a span between maximum and minimum recorded value of 36. The PCDD homologues predominated in 26 out of 32 soil samples, with the ratio (PCDDs)/(PCDFs) ranging from 1.1 to 164; however in the other 6 samples, PCDF homologues were larger, with the same ratio varying from 0.04 to 0.8. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to examine PCDD/F amount and profile in these soil samples, and their possible associations with known emission sources: in this process 6 really distinct isomer fingerprints were identified. Background PCDD/F levels and profiles were comparable to those found in soils from China and other countries and indicate a rather low baseline PCDD/F contamination of soils. The present data provide the tools for future assessment of a possible impact of these MSWIs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Soil Water Adsorption and Evaporation During the Dry Season in an Arid Zone

NASA Astrophysics Data System (ADS)

Agam, N.; Berliner, P. R.

2004-12-01

The purpose of this study was to describe the daily pattern of changes in water content in the upper soil layers of a bare loess soil in the Negev desert throughout the dry season and to assess the corresponding relative magnitude of latent heat flux density. The measurements were carried out in the Northern Negev, Israel, over a bare loess soil, during nine 24-h field campaigns throughout the dry season of 2002. In addition to a micrometeorological station that was set up in the research site, an improved micro-lysimeter was installed. During each campaign, the 100-mm topsoil was sampled hourly, and water content at ten mm increments was obtained. A clear discernible daily cycle of water content in the upper soil layers was observed due to direct adsorption of water vapor by the soil and consequent evaporation. Although the water content of the uppermost soil is significantly lower than the wilting point, for which most of the commonly used meteorological models would assume no latent heat flux, the latter was ˜20% of the net-radiation during the night and 10-15% during the day. It is, therefore, concluded that latent heat flux plays a major role in the dissipation of the net radiation during the dry season in the Negev desert.

Dissolved organic carbon (DOC) in soil extracts investigated by FT-ICR-MS

NASA Astrophysics Data System (ADS)

Hofmann, D.; Steffen, D.; Jablonowski, N. D.; Burauel, P.

2012-04-01

Soil drying and rewetting usually increases the release of xenobiotics like pesticides present in agricultural soils. Besides the effect on the release of two aged 14C-labeled pesticide residues we focus on the characterisation of simultaneously remobilized dissolved organic carbon (DOC) to gain new insights into structure and stability aspects of soil organic carbon fractions. The test soil (gleyic cambisol; Corg 1.2%, pH 7.2) was obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (0-30 cm depth; time of aging: 17 years). Soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45°C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (2000 g). This extraction procedure was repeated several individual times, for both setups. The first three individual extractions, respectively were used for further investigations. Salt was removed from samples prior analysis because of a possible quench effect in the electrospray (ESI) source by solid phase extraction (SPE) with Chromabond C18 Hydra-cartridges (Macherey-Nagel) and methanol as backextraction solvent. The so preconcentrated and desalted samples were introduced by flow injection analysis (FIA) in a fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS), equipped with an ESI source and a 7 T supra-conducting magnet (LTQ-FT Ultra, ThermoFisher Scientific). This technique is the key technique for complex natural systems attributed by their outstanding mass resolution (used 400.000 at m/z 400 Da) and mass accuracy (≤ 1ppm) by simultaneously providing molecular level details of thousands of compounds and was successful applied for the investigations of natural organic matter (NOM) different sources like marine and surface water, soil, sediment, bog and crude oil. The characteristics of measured DOM mass spectra were demonstrated. Furthermore, an algorithm to compute all chemically relevant C,H,O-, C,H,(O,S),N- as well as C,H,(O),S molecular compositions, designed and exercised by ourself using Scilab routines, was used for entire structure elucidation. Various methods for data evaluation of such an amount of peaks are applied to describe the characteristics of DOC. The van Krevelen diagram is widely used to classify the DOC compounds regarding polarity and aromaticity, whereas the Kendrick diagram allow to identify ions with elemental formulas that differ only in CH2, and molecular formulas with similar Kendrick Mass Defect (KMD) can be sorted by nominal mass series. Both kind of diagrams were developed and results are discussed together with the findings of ETD, MBT, and metabolites after soil drying and rewetting. Overall, the results suggest that intermittent soil drying and rewetting alters the disaggregation of soil aggregates, resulting in a release of entrapped organic carbon as well as pesticide molecules.

Relationships between groundwater, surface water, and soil salinity in Polder 32, Southwest Bangladesh

NASA Astrophysics Data System (ADS)

Fry, D. C.; Ayers, J. C.

2014-12-01

In the coastal areas of Southwest Bangladesh polders are surrounded by tidal channels filled with brackish water. In the wet season, farmers create openings in the embankments to irrigate rice paddies. In the dry season, farmers do the same to create saline shrimp ponds. Residents on Polder 32, located within the Ganges-Brahmaputra-Meghna delta system, practice these seasonal farming techniques. Soils in the area are entisols, being sediment recently deposited, and contain mostly silt-sized particles. Brackish water in brine shrimp ponds may deposit salt in the soil, causing soil salinization. However, saline connate groundwater could also be contributing to soil salinization. Groundwater, surface water (fresh water pond, rice paddy and tidal channel water) and soil samples have been analyzed via inductively coupled plasma optical emission spectroscopy, inductively coupled plasma mass spectroscopy and ion chromatography in an attempt to correlate salinity measurements with each other in order to determine major sources of soil salinity. Multiple parameters, including distances of samples from tidal channels, inland streams, shrimp ponds and tube wells were measured to see if spatial correlations exist. Similarly, values from wet and dry seasons were compared to quantify temporal variations. Salt content in many soil samples were found to be high enough to significantly decrease rice yields. Continued soil salinization can decrease these yields even more, leading to farmers not producing enough food to sustain their families.

Soil analysis based on sa,ples withdrawn from different volumes: correlation versus calibration

Treesearch

Lucian Weilopolski; Kurt Johnsen; Yuen Zhang

2010-01-01

Soil, particularly in forests, is replete with spatial variation with respect to soil C. Th e present standard chemical method for soil analysis by dry combustion (DC) is destructive, and comprehensive sampling is labor intensive and time consuming. Th ese, among other factors, are contributing to the development of new methods for soil analysis. Th ese include a near...

Iron Redox Transformations And Phosphorous Cycling In Tropical Soils

NASA Astrophysics Data System (ADS)

Peretyazhko, T.; Sposito, G.

2003-12-01

We are investigating the hypothesis that in highly weathered tropical soils iron oxidation-reduction reactions may mediate phosphorous solubility. In these soils phosphorous may be removed from the plant-available soil pool by sorption to Fe(III) oxides and by precipitation with Fe(III) to form insoluble minerals. The reduction of iron during episodic anoxic conditions has the potential to release phosphorous in a plant available form. We aim to explore the factors controlling Fe reduction and to evaluate the role of Fe reduction in P solubilization. Soil samples were collected along a toposequence (ridge-slope-valley) in the Luquillo Experimental Forest, Puerto Rico. Besides precipitation, the valley soils receive additional water through subsurface and upland runoff. These soils are poorly-drained and, therefore, periodically saturated with water, which creates anoxic conditions. Two series of incubation experiments were carried out on air-dried and freshly-sampled valley soils. During a 14-day incubation period, increasing production of Fe(II) was detected in both types of soil sample. We also found positive correlations between the concentrations of soluble Fe(II), pH, and soluble P. In general, the total amounts of Fe(II) and P produced were higher in the air-dried soil, mainly due to differences in microbial activity. To examine further the factors controlling Fe reduction and P solubilization, we are performing soil incubation experiments in the presence of "electron shuttle" compound (AQDS). SEM and STXM techniques will be applied to detect the formation of Fe(II) secondary minerals.

Wet-dry seasonal and vertical geochemical variations in soil water and their driving forces under different land covers in southwest China karst

NASA Astrophysics Data System (ADS)

Wang, Peng; Hu, Bill X.; Wu, Chuanhao; Xu, Kai

2017-04-01

Karst aquifers supply drinking water for 25% of the world's population, and they are, however, vulnerable to climate change. Bimonthly hydrochemical data in karst soil water samples from July 2010 to July 2011 were obtained to reveal the seasonal and vertical geochemical variations in soil water under five vegetation types in Qingmuguan, a small karst catchment in southwest China. Soil water chemistry was dominated by Ca2+, HCO3-, and SO42- because of the dissolution of limestone, dolomite, and gypsum minerals in the strata. The predominant hydrochemical types in soil water were Ca2+-HCO3-, Ca2+-SO42-, and mixed Ca2+-HCO3-SO42-. Ca2+ and HCO3- concentrations ranked in the following order: shrub land > dry land > afforestation farmland > bamboo land > grassland. In warm and wet seasons, the main ion concentrations in soil water from grasslands were low. Na+, K+, Ca2+, Mg2+, HCO3-, SO42-, and Cl- concentrations in soil water from other lands were high. An opposite trend was observed in cold and dry seasons. Marked seasonal variations were observed in Ca2+, HCO3-, and NO3- in soil water from dry land. The main ion concentrations in soil water from bamboo lands decreased as soil depth increased. By contrast, the chemistry of soil water from other lands increased as soil depth increased. Their ions were accumulated in depth. A consistent high and low variation between the main ions in soil water and the contents of carbonate and CO2 was found in the soil. Hydrochemical changes in soil water were regulated by the effects of dilution and soil CO2.

The Estimation of Compaction Parameter Values Based on Soil Properties Values Stabilized with Portland Cement

NASA Astrophysics Data System (ADS)

Lubis, A. S.; Muis, Z. A.; Pasaribu, M. I.

2017-03-01

The strength and durability of pavement construction is highly dependent on the properties and subgrade bearing capacity. This then led to the idea of the selection methods to estimate the density of the soil with the proper implementation of the system, fast and economical. This study aims to estimate the compaction parameter value namely the maximum dry unit weight (γd max) and optimum moisture content (wopt) of the soil properties value that stabilized with Portland Cement. Tests conducted in the laboratory of soil mechanics to determine the index properties (fines and liquid limit) and Standard Compaction Test. Soil samples that have Plasticity Index (PI) between 0-15% then mixed with Portland Cement (PC) with variations of 2%, 4%, 6%, 8% and 10%, each 10 samples. The results showed that the maximum dry unit weight (γd max) and wopt has a significant relationship with percent fines, liquid limit and the percentation of cement. Equation for the estimated maximum dry unit weight (γd max) = 1.782 - 0.011*LL + 0,000*F + 0.006*PS with R2 = 0.915 and the estimated optimum moisture content (wopt) = 3.441 + 0.594*LL + 0,025*F + 0,024*PS with R2 = 0.726.

Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wildfire

NASA Astrophysics Data System (ADS)

Sun, Q.; Meyer, W. S.; Koerber, G. R.; Marschner, P.

2015-08-01

Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wildfire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content, which could be further modulated by wildfire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy mallee woodland, where part of the woodland experienced a wildfire which destroyed or damaged most of the aboveground plant parts 4 months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80 % of maximum water holding capacity (WHC) for 19 days; in DRW, soils were dried for 4 days, kept dry for another 5 days, then rewetted to 80 % WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per gram of soil in CM and DRW was greater under trees, but lower when expressed per gram of total organic carbon (TOC). Organic matter content, available P, and microbial biomass C, but not available N, were greater under trees than in open areas. Wild fire decreased the flush of respiration per gram of TOC in the open areas and under shrubs, and reduced TOC and microbial biomass C (MBC) concentrations only under trees, but had little effect on available N and P concentrations. We conclude that the impact of wildfire and DRW events on nutrient cycling differs among vegetation patches of a native semi-arid woodland which is related to organic matter amount and availability.

Atmospheric Deposition of Heavy Metals in Soil Affected by Different Soil Uses of Southern Spain

NASA Astrophysics Data System (ADS)

Acosta, J. A.; Faz, A.; Martínez-Martínez, S.; Bech, J.

2009-04-01

Heavy metals are a natural constituent of rocks, sediments and soils. However, the heavy metal content of top soils is also dependent on other sources than weathering of the indigenous minerals; input from atmospheric deposition seems to be an important pathway. Atmospheric deposition is defined as the process by which atmospheric pollutants are transferred to terrestrial and aquatic surfaces and is commonly classified as either dry or wet. The interest in atmospheric deposition has increased over the past decade due to concerns about the effects of deposited materials on the environment. Dry deposition provides a significant mechanism for the removal of particles from the atmosphere and is an important pathway for the loading of heavy metals into the soil ecosystem. Within the last decade, an intensive effort has been made to determine the atmospheric heavy metal deposition in both urban and rural areas. The main objective of this study was to identification of atmospheric heavy metals deposition in soil affected by different soil uses. Study area is located in Murcia Province (southeast of Spain), in the surroundings of Murcia City. The climate is typically semiarid Mediterranean with an annual average temperature of 18°C and precipitation of 350 mm. In order to determine heavy metals atmospheric deposition a sampling at different depths (0-1 cm, 1-5 cm, 5-15 cm and 15-30 cm) was carried out in 7 sites including agricultural soils, two industrial areas and natural sites. The samples were taken to the laboratory where, dried, passed through a 2 mm sieve, and grinded. For the determination of the moisture the samples were weighed and oven dried at 105 °C for 24 h. The total amounts of metals (Pb, Cu, Pb, Zn, Cd, Mn, Ni and Cr) were determined by digesting the samples with nitric/perchoric acids and measuring with ICP-MS. Results showed that zinc contamination in some samples of industrial areas was detected, even this contamination reaches 30 cm depth; thus it is not possible to conclude that the actual contamination by zinc is due to atmospheric deposition or spill. However, some samples in this same area present lightly higher zinc concentration in topsoil than in subsoil indicating a cursory atmospheric deposition. Regarding to lead, one of the industrial areas showed a very active atmospheric deposition, with concentrations higher than 900 mg/kg in topsoil decreasing until less than 10 mg/kg to 30 cm depth. Oppositely, the lead concentration in natural soil is constant in the profile. On the other hand, the range of cadmium concentrations in the different depths of the profiles was, generally, low. Only one sample from the industrial area shows high concentration in the first centimetre of soil, decreasing quickly with the depth, supporting the hypothesis that the atmospheric deposition is the main pathway of cadmium contamination. Studding the copper concentration, only in agricultural soil atmospheric deposition is observed, probably due to application of pesticides. Oppositely to the rest of metals, manganese increases its concentration with the depth in natural soil, probably due to that the parent material (metamorphic rock) is rich in this metal. In the case of chromium has not been detected atmospheric deposition in any sampling point. Finally, only one sample located at the industrial area, nickel concentration shows a higher level in topsoil than subsoil, indicating atmospheric deposition. Acknowledgements: to "Fundación Séneca" of "Comunidad Autónoma de Murcia" for its financial support

Salts in the dry valleys of Antartica

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Presley, B. J.; Hatfield, J.

1984-01-01

The Dry Valleys of Antarctica are examples of polar deserts which are rare geological features on the Earth. Such deserts typically have high salinities associated with their closed-basin waters and on many surficial materials throughout them. In order to examine the possible sources for the salts observed in association with the soils in the Dry Valleys. The chloride and bromide concentrations of the water leachates from 58 soils and core samples were measured. The Cl/Br ratio for seawater is 289 and ratios measured for most of the 58 soils studied (greater than 85% of the soils studied) was larger than the seawater ratio (ratios typically were greater than 1000 and ranged up to 50,000). The enrichment in Cl relative to Br is strong evidence that the alts present within the soils were derived from seawater during ordinary evaporation processes, and not from the deposition of Cl and Br from aerosols or from rock weathering as has often been suggested.

40 CFR 796.2750 - Sediment and soil adsorption isotherm.

Code of Federal Regulations, 2011 CFR

2011-07-01

... size analysis” is the determination of the various amounts of the different particle sizes in a sample... °C. (iii) Replications. Three replications of the experimental treatments shall be used. (iv) Soil...) Decrease the water content, air or oven-dry soils at or below 50 °C. (B) Reduce aggregate size before and...

40 CFR 796.2750 - Sediment and soil adsorption isotherm.

Code of Federal Regulations, 2010 CFR

2010-07-01

... size analysis” is the determination of the various amounts of the different particle sizes in a sample... °C. (iii) Replications. Three replications of the experimental treatments shall be used. (iv) Soil...) Decrease the water content, air or oven-dry soils at or below 50 °C. (B) Reduce aggregate size before and...

Preliminary results on the influence of mineralogy on the turnover rates of SOM from different Hungarian soils

NASA Astrophysics Data System (ADS)

Zacháry, Dóra; Szalai, Zoltán; Jakab, Gergely; Németh, Tibor; Sipos, Péter; Filep, Tibor

2016-04-01

Fine textured soils generally considered containing more microbial biomass, and having a lower rate of biomass turnover and organic matter decomposition than coarse textured soils. In spite of this, several recent studies have shown contradicting trends. For example, the relative importance of different clay minerals for stabilizing SOM remains an open question. The aim of this study is to evaluate soil mineralological effect on the turnover of SOM by identifying and quantifying soil phyllosilicates. Our samples are derived from C3 forests and C3 croplands from different sites of Hungary. C4 maize residues are added to the soils in order to get natural 13C enrichment as tracer for the young carbon. Bulk samples of the soils from 0 to 20 cm depth were collected. The samples were dried at room temperature and preincubated in the dark for 4 months at 20 °C. The basic soil properties (pH, cation exchange capacity) were analysed after 2 mm sieving and homogenization. The amount of total C and N in the soils and maize residues were analysed using NDIR-chemiluminescent analyzer (Tekmar Dohrman Apollo 9000N). Particle size distribution was determined by laser diffraction (Fritsch Analysette MicroTec 22 plus) and particle imaging method (Malvern Morphologi G3-ID). The mineralological composition of the samples was determined by X-ray diffraction (Philips PW 1730 X-ray diffractometer). Moist soil equivalent to 400 g dry soil mixed with 2 g maize leaves is kept in air tight glass chambers for 183 days at 20°C. The leaves had previously been dried at 60 °C, were cut into pieces and sieved through a 2 mm mesh. The evolved CO2 is trapped by 10 mL 2 M NaOH, which is exchanged on day 1, 3, 5, 7, 10, 14, 21, 28 and subsequently every 31 days. The fractional abundance of 13C of the soils, the plant material and the evolved CO2 is measured with isotope ratio mass spectrometer (Thermo Scientific Delta V IRMS). Our work show the preliminary results on the link between phyllosilicate mineralogy and soil C dynamic by reporting a quantified phyllosilicate data in connection with SOM turnover and stabilization. Acknowledgement This research was supported by the Hungarian Scientific National Fund (OTKA K100180).

Measuring Low Concentrations of Liquid Water in Soil

NASA Technical Reports Server (NTRS)

Buehler, Martin

2009-01-01

An apparatus has been developed for measuring the low concentrations of liquid water and ice in relatively dry soil samples. Designed as a prototype of instruments for measuring the liquidwater and ice contents of Lunar and Martian soils, the apparatus could also be applied similarly to terrestrial desert soils and sands. The apparatus is a special-purpose impedance spectrometer: Its design is based on the fact that the electrical behavior of a typical soil sample is well approximated by a network of resistors and capacitors in which resistances decrease and capacitances increase (and, hence, the magnitude of impedance decreases) with increasing water content.

Quantitative ecology and dry-heat resistance of psychrophiles. M.S. Thesis; [in soil samples from Viking spacecraft manufacturing areas

NASA Technical Reports Server (NTRS)

Winans, L., Jr.

1974-01-01

Microorganisms capable of growth at 7 C were enumerated and isolated from soil samples from the manufacture area (Denver, Colorado) and assembly area (Cape Kennedy, Florida) of the Viking spacecraft. Temperature requirements were determined for these isolates, and those growing at 3 C, but not at 32 C were designated as obligate psychrophiles in this investigation. These were identified to major generic groups, and the population density of obligate psychrophiles from the various groups was determined. Dry heat D-values were found for those spores that demonstrated growth or survival under a simulated Martian environment.

Assessment of water sources to plant growth in rice based cropping systems by stable water isotopes

NASA Astrophysics Data System (ADS)

Mahindawansha, Amani; Kraft, Philipp; Racela, Heathcliff; Breuer, Lutz

2016-04-01

Rice is one of the most water-consuming crops in the world. Understanding water source utilization of rice will help us to improve water use efficiency (WUE) in paddy management. The objectives of our study are to evaluate the isotopic compositions of surface ponded water, soil water, irrigation water, groundwater, rain water and plant water and based on stable water isotope signatures to evaluate the contributions of various water sources to plant growth (wet rice, aerobic rice and maize) together with investigating the contribution of water from different soil horizons for plant growth in different maturity periods during wet and dry seasons. Finally we will compare the water balances and crop yields in both crops during both seasons and calculate the water use efficiencies. This will help to identify the most efficient water management systems in rice based cropping ecosystems using stable water isotopes. Soil samples are collected from 9 different depths at up to 60 cm in vegetative, reproductive and matured periods of plant growth together with stem samples. Soil and plant samples are extracted by cryogenic vacuum extraction. Root samples are collected up to 60 cm depth from 10 cm intercepts leading calculation of root length density and dry weight. Groundwater, surface water, rain water and irrigation water are sampled weekly. All water samples are analyzed for hydrogen and oxygen isotope ratios (d18O and dD) using Los Gatos Research DLT100. Rainfall records, ground water level, surface water level fluctuations and the amount of water irrigated in each field will be measured during the sampling period. The direct inference approach which is based on comparing isotopic compositions (dD and d18O) between plant stem water and soil water will be used to determine water sources taken up by plant. Multiple-source mass balance assessment can provide the estimated range of potential contributions of water from each soil depth to root water uptake of a crop. These evaluations will be used to determine the proportion of water from upper soil horizons and deep horizons for rice and maize in different maturity periods during wet and dry seasons. Finally we will estimate the influence of groundwater and surface water by irrigation water and/or by precipitation. First results of the sampling during the wet season 2015 will be presented.

Water soluble cations and the fluvial history of Mars

NASA Technical Reports Server (NTRS)

Silverman, M. P.; Munoz, E. F.

1975-01-01

The electrical conductivity and water soluble Na, K, Ca, and Mg of aqueous solutions of terrestrial soils and finely divided igneous and metamorphic rocks were determined. Soils from dry terrestrial basins with a history of water accumulation as well as soils from the topographic lows of valleys accumulated water soluble cations, particularly Na and Ca. These soils as a group can be distinguished from the rocks or a second group of soils (leached upland soils and soils from sites other than the topographic lows of valleys) by significant differences in their mean electrical conductivity and water-soluble Na + Ca content. Similar measurements on multiple samples from the surface of Mars, collected by an automated long-range roving vehicle along a highlands-to-basin transect at sites with morphological features resembling dry riverlike channels, are suggested to determine the fluvial history of the planet.

Energetic Materials Effects on Essential Soil Processes: Decomposition of Orchard Grass (Dactylis glomerata) Litter in Soil Contaminated with Energetic Materials

DTIC Science & Technology

2014-02-01

moisture level of 14% dry soil mass was maintained for the duration of the study by weekly additions of ASTM Type I water. Soil samples were collected...maintain the initial soil moisture level. One cluster of Orchard grass straw was harvested from a set of randomly selected replicate containers...decomposition is among the most integrating processes within the soil ecosystem because it involves complex interactions of soil microbial, plant , and

Coordinating Chemical and Mineralogical Analyses of Antarctic Dry Valley Sediments as Potential Analogs for Mars

NASA Technical Reports Server (NTRS)

Patel, S. N.; Bishop, J. L.; Englert, P.; Gibson, E. K.

2015-01-01

The Antarctic Dry Valleys (ADV) provide a unique terrestrial analog for Martian surface processes as they are extremely cold and dry sedimentary environments. The surface geology and the chemical composition of the Dry Valleys that are similar to Mars suggest the possible presence of these soil-formation processes on Mars. The soils and sediments from Wright Valley, Antarctica were investigated in this study to examine mineralogical and chemical changes along the surface layer in this region and as a function of depth. Surface samples collected near Prospect Mesa and Don Juan Pond of the ADV were analyzed using visible/near-infrared (VNIR) and mid-IR reflectance spectroscopy and major and trace element abundances.

Effects of leachate on geotechnical characteristics of sandy clay soil

NASA Astrophysics Data System (ADS)

Harun, N. S.; Ali, Z. Rahman; Rahim, A. S.; Lihan, T.; Idris, R. M. W.

2013-11-01

Leachate is a hazardous liquid that poses negative impacts if leaks out into environments such as soil and ground water systems. The impact of leachate on the downgraded quality in terms of chemical characteristic is more concern rather than the physical or mechanical aspect. The effect of leachate on mechanical behaviour of contaminated soil is not well established and should be investigated. This paper presents the preliminary results of the effects of leachate on the Atterberg limit, compaction and shear strength of leachate-contaminated soil. The contaminated soil samples were prepared by mixing the leachate at ratiosbetween 0% and 20% leachate contents with soil samples. Base soil used was residual soil originated from granitic rock and classified as sandy clay soil (CS). Its specific gravity ranged between 2.5 and 2.64 with clay minerals of kaolinite, muscovite and quartz. The field strength of the studied soil ranged between 156 and 207 kN/m2. The effects of leachate on the Atterberg limit clearly indicated by the decrease in liquid and plastic limit values with the increase in the leachate content. Compaction tests on leachate-contaminated soil caused the dropped in maximum dry density, ρdry and increased in optimum moisture content, wopt when the amount of leachate was increased between 0% and 20%. The results suggested that leachate contamination capable to modify some geotechnical properties of the studied residual soils.

Brazilian Cerrado soil Actinobacteria ecology.

PubMed

Suela Silva, Monique; Naves Sales, Alenir; Teixeira Magalhães-Guedes, Karina; Ribeiro Dias, Disney; Schwan, Rosane Freitas

2013-01-01

A total of 2152 Actinobacteria strains were isolated from native Cerrado (Brazilian Savannah) soils located in Passos, Luminárias, and Arcos municipalities (Minas Gerais State, Brazil). The soils were characterised for chemical and microbiological analysis. The microbial analysis led to the identification of nine genera (Streptomyces, Arthrobacter, Rhodococcus, Amycolatopsis, Microbacterium, Frankia, Leifsonia, Nakamurella, and Kitasatospora) and 92 distinct species in both seasons studied (rainy and dry). The rainy season produced a high microbial population of all the aforementioned genera. The pH values of the soil samples from the Passos, Luminárias, and Arcos regions varied from 4.1 to 5.5. There were no significant differences in the concentrations of phosphorus, magnesium, and organic matter in the soils among the studied areas. Samples from the Arcos area contained large amounts of aluminium in the rainy season and both hydrogen and aluminium in the rainy and dry seasons. The Actinobacteria population seemed to be unaffected by the high levels of aluminium in the soil. Studies are being conducted to produce bioactive compounds from Actinobacteria fermentations on different substrates. The present data suggest that the number and diversity of Actinobacteria spp. in tropical soils represent a vast unexplored resource for the biotechnology of bioactives production.

Brazilian Cerrado Soil Actinobacteria Ecology

PubMed Central

Suela Silva, Monique; Naves Sales, Alenir; Teixeira Magalhães-Guedes, Karina; Ribeiro Dias, Disney; Schwan, Rosane Freitas

2013-01-01

A total of 2152 Actinobacteria strains were isolated from native Cerrado (Brazilian Savannah) soils located in Passos, Luminárias, and Arcos municipalities (Minas Gerais State, Brazil). The soils were characterised for chemical and microbiological analysis. The microbial analysis led to the identification of nine genera (Streptomyces, Arthrobacter, Rhodococcus, Amycolatopsis, Microbacterium, Frankia, Leifsonia, Nakamurella, and Kitasatospora) and 92 distinct species in both seasons studied (rainy and dry). The rainy season produced a high microbial population of all the aforementioned genera. The pH values of the soil samples from the Passos, Luminárias, and Arcos regions varied from 4.1 to 5.5. There were no significant differences in the concentrations of phosphorus, magnesium, and organic matter in the soils among the studied areas. Samples from the Arcos area contained large amounts of aluminium in the rainy season and both hydrogen and aluminium in the rainy and dry seasons. The Actinobacteria population seemed to be unaffected by the high levels of aluminium in the soil. Studies are being conducted to produce bioactive compounds from Actinobacteria fermentations on different substrates. The present data suggest that the number and diversity of Actinobacteria spp. in tropical soils represent a vast unexplored resource for the biotechnology of bioactives production. PMID:23555089

Assessment of in situ and ex situ phytorestoration with grass mixtures in soils polluted with nickel, copper, and arsenic

NASA Astrophysics Data System (ADS)

Zacarías Salinas, Montserrat; Beltrán Villavicencio, Margarita; Bustillos, Luis Gilberto Torres; González Aragón, Abelardo

This work shows a study of in situ and ex situ phytoextraction as a polishing step in the treatment of an industrial urban soil polluted with nickel, arsenic and copper. The soil was previously washed, and phytoextraction was performed by application of a mixture of grass (Festuca rubra, Cynodon dactylon, Lolium multiforum, Pennisetum). The soil had initial heavy metals concentrations of 131 ppm for Ni, 717 for As and 2734 for Cu (mg of metal/kg of dry soil). After seeding and emerging of grass, vegetal and soil samples were taken monthly during 4 months. Biomass generation, and concentration of Ni, As and Cu in vegetal tissue and soil were determined for every sample. Plants biomass growth in ex situ process was inhibited by 37% when compared with blank soil. Grass showed remarkable phytoextraction capability in situ, it produced 38 g of biomass every 15 days (wet weight) during a period of 3 months, but then declined in the fourth month. Concentrations of metals in grass biomass were up to 83 mg Ni/kg, 649 mg As/kg and 305 mg Cu/kg dry weight. Metal reduction of 49% for Ni, and 35% for Cu and As was observed at rhizospheric soil.

Detecting and enumerating soil-transmitted helminth eggs in soil: New method development and results from field testing in Kenya and Bangladesh.

PubMed

Steinbaum, Lauren; Kwong, Laura H; Ercumen, Ayse; Negash, Makeda S; Lovely, Amira J; Njenga, Sammy M; Boehm, Alexandria B; Pickering, Amy J; Nelson, Kara L

2017-04-01

Globally, about 1.5 billion people are infected with at least one species of soil-transmitted helminth (STH). Soil is a critical environmental reservoir of STH, yet there is no standard method for detecting STH eggs in soil. We developed a field method for enumerating STH eggs in soil and tested the method in Bangladesh and Kenya. The US Environmental Protection Agency (EPA) method for enumerating Ascaris eggs in biosolids was modified through a series of recovery efficiency experiments; we seeded soil samples with a known number of Ascaris suum eggs and assessed the effect of protocol modifications on egg recovery. We found the use of 1% 7X as a surfactant compared to 0.1% Tween 80 significantly improved recovery efficiency (two-sided t-test, t = 5.03, p = 0.007) while other protocol modifications-including different agitation and flotation methods-did not have a significant impact. Soil texture affected the egg recovery efficiency; sandy samples resulted in higher recovery compared to loamy samples processed using the same method (two-sided t-test, t = 2.56, p = 0.083). We documented a recovery efficiency of 73% for the final improved method using loamy soil in the lab. To field test the improved method, we processed soil samples from 100 households in Bangladesh and 100 households in Kenya from June to November 2015. The prevalence of any STH (Ascaris, Trichuris or hookworm) egg in soil was 78% in Bangladesh and 37% in Kenya. The median concentration of STH eggs in soil in positive samples was 0.59 eggs/g dry soil in Bangladesh and 0.15 eggs/g dry soil in Kenya. The prevalence of STH eggs in soil was significantly higher in Bangladesh than Kenya (chi-square, χ2 = 34.39, p < 0.001) as was the concentration (Mann-Whitney, z = 7.10, p < 0.001). This new method allows for detecting STH eggs in soil in low-resource settings and could be used for standardizing soil STH detection globally.

Detecting and enumerating soil-transmitted helminth eggs in soil: New method development and results from field testing in Kenya and Bangladesh

PubMed Central

Kwong, Laura H.; Ercumen, Ayse; Negash, Makeda S.; Lovely, Amira J.; Njenga, Sammy M.; Boehm, Alexandria B.; Pickering, Amy J.; Nelson, Kara L.

2017-01-01

Globally, about 1.5 billion people are infected with at least one species of soil-transmitted helminth (STH). Soil is a critical environmental reservoir of STH, yet there is no standard method for detecting STH eggs in soil. We developed a field method for enumerating STH eggs in soil and tested the method in Bangladesh and Kenya. The US Environmental Protection Agency (EPA) method for enumerating Ascaris eggs in biosolids was modified through a series of recovery efficiency experiments; we seeded soil samples with a known number of Ascaris suum eggs and assessed the effect of protocol modifications on egg recovery. We found the use of 1% 7X as a surfactant compared to 0.1% Tween 80 significantly improved recovery efficiency (two-sided t-test, t = 5.03, p = 0.007) while other protocol modifications—including different agitation and flotation methods—did not have a significant impact. Soil texture affected the egg recovery efficiency; sandy samples resulted in higher recovery compared to loamy samples processed using the same method (two-sided t-test, t = 2.56, p = 0.083). We documented a recovery efficiency of 73% for the final improved method using loamy soil in the lab. To field test the improved method, we processed soil samples from 100 households in Bangladesh and 100 households in Kenya from June to November 2015. The prevalence of any STH (Ascaris, Trichuris or hookworm) egg in soil was 78% in Bangladesh and 37% in Kenya. The median concentration of STH eggs in soil in positive samples was 0.59 eggs/g dry soil in Bangladesh and 0.15 eggs/g dry soil in Kenya. The prevalence of STH eggs in soil was significantly higher in Bangladesh than Kenya (chi-square, χ2 = 34.39, p < 0.001) as was the concentration (Mann-Whitney, z = 7.10, p < 0.001). This new method allows for detecting STH eggs in soil in low-resource settings and could be used for standardizing soil STH detection globally. PMID:28379956

Alternate wetting and drying decreases methylmercury in flooded rice (Oryza sativa) systems

USGS Publications Warehouse

Tanner, K. Christy; Windham-Myers, Lisamarie; Marvin-DiPasquale, Mark C.; Fleck, Jacob; Linquist, Bruce A.

2018-01-01

In flooded soils, including those found in rice (Oryza sativa L.) fields, microbes convert inorganic Hg to more toxic methylmercury (MeHg). Methylmercury is accumulated in rice grain, potentially affecting health. Methylmercury in rice field surface water can bioaccumulate in wildlife. We evaluated how introducing aerobic periods into an otherwise continuously flooded rice growing season affects MeHg dynamics. Conventional continuously flooded (CF) rice field water management was compared with alternate wetting and drying, where irrigation was stopped twice during the growing season, allowing soil to dry to 35% volumetric moisture content, at which point plots were reflooded (AWD-35). Methylmercury studies began at harvest in Year 3 and throughout Year 4 of a 4-yr replicated field experiment. Bulk soil, water, and plant samples were analyzed for MeHg and total Hg (THg), and iron (Fe) speciation was measured in soil samples. Rice grain yield over 4 yr did not differ between treatments. Soil chemistry responded quickly to AWD-35 dry-downs, showing significant oxidation of Fe(II) accompanied by a significant reduction of MeHg concentration (76% reduction at harvest) compared with CF. Surface water MeHg decreased by 68 and 39% in the growing and fallow seasons, respectively, suggesting that the effects of AWD-35 management can last through to the fallow season. The AWD-35 treatment reduced rice grain MeHg and THg by 60 and 32%, respectively. These results suggest that the more aerobic conditions caused by AWD-35 limited the activity of Hg(II)-methylating microbes and may be an effective way to reduce MeHg concentrations in rice ecosystems.

Experimental investigation of infiltration in soil with occurrence of preferential flow and air trapping

NASA Astrophysics Data System (ADS)

Snehota, Michal; Jelinkova, Vladimira; Sacha, Jan; Cislerova, Milena

2015-04-01

Recently, a number of infiltration experiments have not proved the validity of standard Richards' theory of the flow in soils with wide pore size distribution. Water flow in such soils under near-saturated conditions often exhibits preferential flow and temporal instability of the saturated hydraulic conductivity. An intact sample of coarse sandy loam from Cambisol series containing naturally developed vertically connected macropore was investigated during recurrent ponding infiltration (RPI) experiments conducted during period of 30 hours. RPI experiment consisted of two ponded infiltration runs, each followed by free gravitational draining of the sample. Three-dimensional neutron tomography (NT) image of the dry sample was acquired before the infiltration begun. The dynamics of the wetting front advancement was investigated by a sequence of neutron radiography (NR) images. Analysis of NR showed that water front moved preferentially through the macropore at the approximate speed of 2 mm/sec, which was significantly faster pace than the 0.3 mm/sec wetting advancement in the surrounding soil matrix. After the water started to flow out of the sample, changes in the local water content distribution were evaluated quantitatively by subtracting the NT image of the dry sample from subsequent tomography images. As a next stage, the experiment was repeated on a composed sample packed of ceramic and coarse sand. Series of infiltration runs was conducted in the sample with different initial water contents. The neutron tomography data quantitatively showed that both in natural soil sample containing the macropore and in the composed sample air was gradually transported from the region of fine soil matrix to the macropores or to the coarser material. The accumulation of the air bubbles in the large pores affected the hydraulic conductivity of the sample reducing it up to 50% of the initial value. This supports the hypothesis on strong influence of entrapped air amount and spatial distribution on infiltration into heterogeneous soils. The research was supported by the Czech Science Foundation Project No. 14-03691S.

Column Experiments Investigating Wetting and Drying of Soil and Consumption of Organic Contaminants for Managed Aquifer Recharge

NASA Astrophysics Data System (ADS)

Silver, M.; Schueth, C.; Wefer-Roehl, A.; Kuebeck, C.

2014-12-01

The EU FP7 project MARSOL seeks to address water scarcity challenges in arid regions. Within this framework, we conduct a series of experiments to evaluate the potential for water quality improvement and changes in hydraulic conductivity when managed aquifer recharge (MAR) is performed by infiltrating treated wastewater in soils that do not have high potential for sorption. For example, in the Attica (Athens and vicinity) region of Greece, the bedrock is mostly marble, resulting in calcite-rich soils that present little potential for sorption of contaminants to mineral surfaces. This leaves consumption of organic contaminants by microbes as the critical mechanism for water quality improvement, when treated wastewater is infiltrated through such soils. In order to enhance the potential for contaminant consumption by aerobic bacteria in a way that would be realistic to later perform in an infiltration basin, we conduct experiments using a series of wetting and drying cycles. The experimental setup consists of 90-cm long soil columns, fitted with oxygen sensors, time-domain reflectometry sensors (to measure moisture content), sampling ports, oxidation-reduction probes, and head observation tubes. We use the data collected from these sensors and features of the experimental setup to answer the following questions: 1. Does hydraulic conductivity change, from formation of a biofilm or dissolution of calcite (or both)? 2. Are organic contaminants consumed? 3. What effect do wetting and drying cycles have on consumption of organic contaminants? 4. How long can infiltration of treated wastewater last, before oxygen is consumed and conditions become reducing? These questions are investigated by observing the hydraulic head and outflow, performing tracer tests, taking samples from the sampling ports and outflow for chemical analyses, and measuring moisture content and oxygen concentration, in the course of performing multiple wetting and drying cycles. These column experiments will be used to evaluate the potential for new MAR applications in areas facing water scarcity challenges. In the future the experiments will be expanded to test multiple soils and optimize both the soil type and infiltration patterns in order to best obtain water quality improvements through MAR.

Opportune Landing Site Program: Opportune Landing Site Southeastern Indiana Field Data Collection and Assessment

DTIC Science & Technology

2008-11-01

consisted of eight fundamental tasks. Boeing (1) pro - vided software allowing the selection of OLS locations using satellite im- agery, (2) provided a...IOP1 to determine the stratigraphy of the soil horizons, collect samples to determine the soil texture, and collect pro - file measurements of the soil...However, using the wet density value from the gauge with an oven-dry moisture con - tent from a sample collected at the same location where the density

Survival of Legionella in earthquake-induced soil disturbance (liquefaction) in residential areas, Christchurch, New Zealand: implications for disease.

PubMed

Graham, Frances F; Harte, David Jg

2017-05-12

To investigate a possible link between liquefaction dust exposure and the noticeable increase in legionellosis cases in response to major earthquakes in 2010 and 2011 that resulted in widespread soil disturbance (liquefaction) in parts of Christchurch, New Zealand. We culture tested liquefaction-affected soil for Legionella spp. in the six months following the first earthquake in 2010. Thirty silt samples were collected randomly from locations within Christchurch's metropolitan area that were affected by liquefaction. The samples were tested to determine the presence of Legionella using qualitative and quantitative methods. Liquefaction-affected soil samples from three sites were further subjected to particle size distribution analysis and determination of major oxides. A controlled field study was established using six silt samples and one control (commercial compost), seeded with a wild-type strain of Legionella bozemanae serogroup (sg) 1 and persistence monitored over a 60-day period by culturing for the presence of Legionella. Dry matter determinations were undertaken so that total Legionella could be calculated on a dry weight basis. Legionella bacteria were undetectable after day one in the silt samples. However, L. bozemanae sg1 was detected in the control sample for the entire study period. This study showed that the liquefaction-affected soil could not contribute directly to the observed increase in legionellosis cases after the earthquakes due to its inability to support growth and survival of the Legionella bacteria.

Thermoradiation inactivation of naturally occurring organisms in soil

NASA Technical Reports Server (NTRS)

Reynolds, M. C.; Lindell, K. F.; David, T. J.

1973-01-01

Samples of soil collected from Kennedy Space Center near spacecraft assembly facilities were found to contain microorganisms very resistant to conventional sterilization techniques. The inactivation behavior of the naturally occurring spores in soil was investigated using dry heat and ionizing radiation, first separately, then in combination. Dry heat inactivation rates of spores were determined for 105 and 125 C. Radiation inactivation rates were determined for dose rates of 660 and 76 krad/hr at 25 C. Simultaneous combinations of heat and radiation were then investigated at 105, 110, 115, 120, and 125 C. Combined treatment was found to be highly synergistic requiring greatly reduced radiation doses to accomplish sterilization.

Freezing and drying effects on potential plant contributions to phosphorus in runoff.

PubMed

Roberson, Tiffany; Bundy, Larry G; Andraski, Todd W

2007-01-01

Phosphorus (P) in runoff from landscapes can promote eutrophication of natural waters. Soluble P released from plant material can contribute significant amounts of P to runoff particularly after plant freezing or drying. This study was conducted to evaluate P losses from alfalfa or grass after freezing or drying as potential contributors to runoff P. Alfalfa (Medicago sativa L.) and grass (principally, Agropyron repens L.) plant samples were subjected to freezing and drying treatments to determine P release. Simulated rainfall runoff and natural runoff from established alfalfa fields and a grass waterway were collected to study P contributions from plant tissue to runoff. The effects of freezing and drying on P released from plant tissue were simulated by a herbicide treatment in selected experiments. Soluble reactive P (SP) extracted from alfalfa and grass samples was markedly increased by freezing or drying. In general, SP extracted from plant samples increased in the order fresh < frozen < frozen/thawed < dried, and averaged 1, 8, 14, and 26% of total P in alfalfa, respectively. Soluble reactive P extracted from alfalfa after freezing or drying increased with increasing soil test P (r(2) = 0.64 to 0.68), suggesting that excessive soil P levels increased the risk of plant P contributions to runoff losses. In simulated rainfall studies, paraquat (1,1'-dimethyl-4, 4''-bipyridinium ion) treatment of alfalfa increased P losses in runoff, and results suggested that this treatment simulated the effects of drying on plant P loss. In contrast to the simulated rainfall results, natural runoff studies over 2 yr did not show higher runoff P losses that could be attributed to P from alfalfa. Actual P losses likely depend on the timing and extent of plant freezing and drying and of precipitation events after freezing.

Biogenic NO emission from a spruce forest soil in the Fichtelgebirge (Germany) under the influence of different understorey vegetation cover

NASA Astrophysics Data System (ADS)

Bargsten, A.; Andreae, M. O.; Meixner, F. X.

2009-04-01

Within the framework of the EGER project (ExchanGE processes in mountainous Regions) soil samples have been taken from the spruce forest site "Weidenbrunnen" (Fichtelgebirge, Germany) in September 2008 to determine the NO exchange in the laboratory and for a series of soil analyses. The soil was sampled below different understorey vegetation covers: young Norway spruce, moss/litter, blueberries and grass. We investigated the net NO release rate from corresponding organic layers as well as from the A horizon of respective soils. Additionally we measured pH, C/N ratio, contents of ammonium, nitrate, and organic C, bulk density, the thickness of the organic layer and the quality of the organic matter. Net NO release rates (as well as the NO production and NO consumption rates) from the soil samples were determined by a fully automated laboratory incubation & fumigation system. Purified dry air passed five dynamic incubation chambers, four containing water saturated soil samples and one reference chamber. By this procedure, the soil samples dried out slowly (within 2-6 days), covering the full range of soil moisture (0-300% gravimetric soil moisture). To quantify NO production and NO consumption rates separately, soil samples were fumigated with zero-air (approx. 0 ppb NO) and air of 133 ppb NO. The chambers were placed in a thermostatted cabinet for incubation at 10 an 20˚ C. NO and H2O concentrations at the outlet of the five dynamic chambers were measured sequentially by chemiluminescence and IR-absorption based analyzers, switching corresponding valves every two minutes. Net NO release rates were determined from the NO concentration difference between soil containing and reference chambers. Corresponding measurements of H2O mixing ratio yielded the evaporation loss of the soil samples, which (referenced to the gravimetric soil water content before and after the incubation experiment) provided the individual soil moisture contents of each soil samples during the incubation experiment. Our contribution focus net NO release rates, NO production and NO consumption rates of spruce forest soils sampled under different understorey vegetation covers. Generally, organic layers show significant higher NO production and NO consumption rates than the soils from the corresponding A horizons. Soils under the understorey vegetation cover "moos/litter" revealed the lowest NO production and NO consumption rates. Net NO release rates, NO production and NO consumption rates of soil samples obtained below the four different under- storey vegetation covers will be discussed in terms of pH, C/N ratio, contents of ammonium, nitrate, and organic C, bulk density, thickness of organic layer, as well as quality of the organic matter.

Content and bioconcentration of mercury in mushrooms from northern Poland.

PubMed

Falandysz, J; Gucia, M; Brzostowski, A; Kawano, M; Bielawski, L; Frankowska, A; Wyrzykowska, B

2003-03-01

Mercury (Hg) was quantified using cold vapour-atomic absorption spectrometry (CV-AAS) in the fruiting bodies of nine edible and five inedible mushrooms and in underlying soil substrate samples. In total, 404 samples comprising caps and stalks and 202 samples of soil substrate (0-10 cm layer) were collected in 1996 from Trójmiejski Landscape Park, northern Poland. Mean Hg concentrations in the soil substrate for different species varied between 10 +/- 3 and 780 +/- 500 ng x g(-1) dry wt (range 2.3-1700). Among edible mushroom species, Horse Mushroom (Agaricus arvensis), Brown Birch Scaber Stalk (Leccinum scabrum), Parasol Mushroom (Macrolepiota procera), King Bolete (Boletus edulis) and Yellow-cracking Bolete (Xerocomus subtomentosus) contained elevated concentrations of Hg ranging from 1600 +/- 930 to 6800 +/- 4000 ng x g(-1) dry wt in the caps. Concentrations of Hg in the stalks were 2.6 +/- 1.1 to 1.7 +/- 1.0 times lower than those in the caps. Some mushroom species investigated had high Hg levels when compared with specimens collected from the background reference sites elsewhere (located far away from the big cities) in northern Poland. Bioconcentration factors of Hg in the caps of Horse Mushroom, Parasol Mushroom and Brown Birch Scaber Stalk were between 150 +/- 58 and 230 +/- 150 ng x g(-1) dry wt, respectively, and for inedible Pestle-shaged Puffball (Claviata excipulformis) was 960 +/- 300 ng x g(-1) dry wt. Linear regression coefficients between Hg in caps and in stalks and Hg soil concentrations showed a positive relationship for A. arvensis and Horse mushroom (p < 0.05) and a negative correlation for the caps of Death Caps (Amanita phalloides) and Woolly Milk Cap (Lactarius torminosus) (p < 0.05), while for other species no clear trend was found.

Photometric properties of Mars soils analogs

USGS Publications Warehouse

Pommerol, A.; Thomas, N.; Jost, B.; Beck, P.; Okubo, C.; McEwen, A.S.

2013-01-01

We have measured the bidirectional reflectance of analogs of dry, wet, and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their microtexture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward-scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

Soil Ingestion is Associated with Child Diarrhea in an Urban Slum of Nairobi, Kenya.

PubMed

Bauza, Valerie; Ocharo, R M; Nguyen, Thanh H; Guest, Jeremy S

2017-03-01

Diarrhea is a leading cause of mortality in children under 5 years of age. We conducted a cross-sectional study of 54 children aged 3 months to 5 years old in Kibera, an urban slum in Nairobi, Kenya, to assess the relationship between caregiver-reported soil ingestion and child diarrhea. Diarrhea was significantly associated with soil ingestion (adjusted odds ratio = 9.9, 95% confidence interval = 2.1-47.5). Soil samples from locations near each household were also collected and analyzed for Escherichia coli and a human-associated Bacteroides fecal marker (HF183). Escherichia coli was detected in 100% of soil samples (mean 5.5 log colony forming units E. coli per gram of dry soil) and the Bacteroides fecal marker HF183 was detected in 93% of soil samples. These findings suggest that soil ingestion may be an important transmission pathway for diarrheal disease in urban slum settings.

Soil Ingestion is Associated with Child Diarrhea in an Urban Slum of Nairobi, Kenya

PubMed Central

Bauza, Valerie; Ocharo, R. M.; Nguyen, Thanh H.; Guest, Jeremy S.

2017-01-01

Diarrhea is a leading cause of mortality in children under 5 years of age. We conducted a cross-sectional study of 54 children aged 3 months to 5 years old in Kibera, an urban slum in Nairobi, Kenya, to assess the relationship between caregiver-reported soil ingestion and child diarrhea. Diarrhea was significantly associated with soil ingestion (adjusted odds ratio = 9.9, 95% confidence interval = 2.1–47.5). Soil samples from locations near each household were also collected and analyzed for Escherichia coli and a human-associated Bacteroides fecal marker (HF183). Escherichia coli was detected in 100% of soil samples (mean 5.5 log colony forming units E. coli per gram of dry soil) and the Bacteroides fecal marker HF183 was detected in 93% of soil samples. These findings suggest that soil ingestion may be an important transmission pathway for diarrheal disease in urban slum settings. PMID:28093532

Does monensin in chicken manure from poultry farms pose a threat to soil invertebrates?

PubMed

Zižek, Suzana; Hrženjak, Rok; Kalcher, Gabrijela Tavčar; Srimpf, Karin; Semrov, Neva; Zidar, Primož

2011-04-01

Monensin is a carboxylic polyether ionophore used in the poultry industry as a coccidiostat. It enters the environment via manure from broiler farms. In spite of its potential presence in the environment, information concerning monensin residues in manure and soil and its toxicity to soil organisms are insufficient. In the present study, two beneficial soil invertebrate species, earthworms (Eisenia andrei) and woodlice (Porcellio scaber), were used to assess the toxicity of monensin. Animals were exposed to a range of monensin concentrations via soil or food. Earthworm reproduction was found to be the most susceptible endpoint (NOEC=3.5 mg kg(-1) dry soil; EC(50)=12.7 mg kg(-1) dry soil), while no adverse effects were recorded in isopods (NOEC⩾849mgkg(-1) dry soil, NOEC⩾357mgkg(-1) dry food). The obtained toxicity data were compared with potential concentrations of monensin in soil. In view of this, manure from broiler chickens treated with monensin at a poultry farm was sampled. According to monensin and nitrogen concentrations in the chicken manure and the degradation time of monensin, the predicted environmental concentration (PEC) was calculated. PEC of monensin is around 0.013 mg kg(-1) soil if manure is used after 3 months of composting and 0.05 mg kg(-1) soil if used without storage. Data for earthworm reproduction was used to estimate the predicted no-effect concentration (PNEC). If fresh chicken manure is applied to terrestrial ecosystems, the risk quotient (PEC/PNEC ratio) is above 1, which indicates that monensin might pose an environmental risk under certain conditions. To prevent this, it is strongly recommended to compost chicken manure for several months before using it as fertiliser. Copyright © 2010 Elsevier Ltd. All rights reserved.

Water retention of repellent and subcritical repellent soils: New insights from model and experimental investigations

NASA Astrophysics Data System (ADS)

Czachor, H.; Doerr, S. H.; Lichner, L.

2010-01-01

SummarySoil organic matter can modify the surface properties of the soil mineral phase by changing the surface tension of the mineral surfaces. This modifies the soil's solid-water contact angle, which in turn would be expected to affect its water retention curve (SWRC). Here we model the impact of differences in the soil pore-water contact angle on capillarity in non-cylindrical pores by accounting for their complex pore geometry. Key outcomes from the model include that (i) available methods for measuring the Young's wetting angle on soil samples are insufficient in representing the wetting angle in the soil pore space, (ii) the wetting branch of water retention curves is strongly affected by the soil pore-water contact angle, as manifest in the wetting behavior of water repellent soils, (iii) effects for the drying branch are minimal, indicating that both wettable and water repellent soils should behave similarly, and (vi) water retention is a feature not of only wettable soils, but also soils that are in a water repellent state. These results are tested experimentally by determining drying and wetting branches for (a) 'model soil' (quartz sands with four hydrophobization levels) and (b) five field soil samples with contrasting wettability, which were used with and without the removal of the soil organic matter. The experimental results support the theoretical predictions and indicate that small changes in wetting angle can cause switches between wettable and water repellent soil behavior. This may explain the common observation that relatively small changes in soil water content can cause substantial changes in soil wettability.

Semiquantitative color profiling of soils over a land degradation gradient in Sakaerat, Thailand.

PubMed

Doi, Ryoichi; Wachrinrat, Chongrak; Teejuntuk, Sakhan; Sakurai, Katsutoshi; Sahunalu, Pongsak

2010-11-01

In this study, we attempted multivariate color profiling of soils over a land degradation gradient represented by dry evergreen forest (original vegetation), dry deciduous forest (moderately disturbed by fire), and bare ground (severely degraded) in Sakaerat, Thailand. The soils were sampled in a dry-to-wet seasonal transition. Values of the red-green-blue (RGB), cyan-magenta-yellow-key black (CMYK), L*a*b*, and hue-intensity-saturation (HIS) color models were determined using the digital software Adobe Photoshop. Land degradation produced significant variations (p<0.05) in R, C, Y, L*, a*, b*, S, and I values (p<0.05). The seasonal transition produced significant variations (p<0.05) in R, G, B, C, M, K, L*, b*, and I values. In discriminating the soils, the color models did not differ in discriminatory power, while discriminatory power was affected by seasonal changes. Most color variation patterns had nonlinear relationships with the intensity of the land degradation gradient, due to effects of fire that darkened the deciduous forest soil, masking the nature of the soil as the intermediate between the evergreen forest and the bare ground soils. Taking these findings into account, the utilization of color profiling of soils in land conservation and rehabilitation is discussed.

Water regime influences bulk soil and Rhizosphere of Cereus jamacaru bacterial communities in the Brazilian Caatinga biome.

PubMed

Nessner Kavamura, Vanessa; Taketani, Rodrigo Gouvêa; Lançoni, Milena Duarte; Andreote, Fernando Dini; Mendes, Rodrigo; Soares de Melo, Itamar

2013-01-01

We used the T-RFLP technique combined with Ion Torrent (PGM) sequencing of 16S rRNA and multivariate analysis to study the structure of bulk soil and rhizosphere bacterial communities of a cactus, Cereus jamacaru, from the Brazilian Caatinga biome, which is unique to Brazil. The availability of water shapes the rhizosphere communities, resulting in different patterns during the rainy and dry seasons. Taxonomic approaches and statistical analysis revealed that the phylum Actinobacteria strongly correlated with the dry season, while samples from the rainy season exhibited a strong correlation with the phylum Proteobacteria for rhizosphere samples and with the phyla Bacteroidetes, Firmicutes, Lentisphaerae, and Tenericutes for bulk soil samples. The STAMP software also indicated that the phylum Bacteroidetes, as well as two classes in the Proteobacteria phylum (γ and δ), were the most significant ones during the rainy season. The average abundance of the phylum Actinobacteria and the genus Bacillus was significantly greater during the dry season. Some significant genera found during the dry season might reflect their tolerance to the extreme conditions found in the Caatinga biome. They may also indicate the ecological function that microorganisms play in providing plants with some degree of tolerance to water stress or in assisting in their development through mechanisms of growth promotion. Alterations in microbial communities can be due to the different abilities of native microorganisms to resist and adapt to environmental changes.

Water Regime Influences Bulk Soil and Rhizosphere of Cereus jamacaru Bacterial Communities in the Brazilian Caatinga Biome

PubMed Central

Nessner Kavamura, Vanessa; Taketani, Rodrigo Gouvêa; Lançoni, Milena Duarte; Andreote, Fernando Dini; Mendes, Rodrigo; Soares de Melo, Itamar

2013-01-01

We used the T-RFLP technique combined with Ion Torrent (PGM) sequencing of 16S rRNA and multivariate analysis to study the structure of bulk soil and rhizosphere bacterial communities of a cactus, Cereus jamacaru, from the Brazilian Caatinga biome, which is unique to Brazil. The availability of water shapes the rhizosphere communities, resulting in different patterns during the rainy and dry seasons. Taxonomic approaches and statistical analysis revealed that the phylum Actinobacteria strongly correlated with the dry season, while samples from the rainy season exhibited a strong correlation with the phylum Proteobacteria for rhizosphere samples and with the phyla Bacteroidetes, Firmicutes, Lentisphaerae, and Tenericutes for bulk soil samples. The STAMP software also indicated that the phylum Bacteroidetes, as well as two classes in the Proteobacteria phylum (γ and δ), were the most significant ones during the rainy season. The average abundance of the phylum Actinobacteria and the genus Bacillus was significantly greater during the dry season. Some significant genera found during the dry season might reflect their tolerance to the extreme conditions found in the Caatinga biome. They may also indicate the ecological function that microorganisms play in providing plants with some degree of tolerance to water stress or in assisting in their development through mechanisms of growth promotion. Alterations in microbial communities can be due to the different abilities of native microorganisms to resist and adapt to environmental changes. PMID:24069212

Role of Biotic and Abiotic Processes on Soil CO2 Dynamics in the McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Risk, D. A.; Macintyre, C. M.; Lee, C.; Cary, C.; Shanhun, F.; Almond, P. C.

2016-12-01

In the harsh conditions of the Antarctic Dry Valleys, microbial activity has been recorded via measurements of soil carbon dioxide (CO2) concentration and surface efflux. However, high temporal resolution studies in the Dry Valleys have also shown that abiotic solubility-driven processes can strongly influence (and perhaps even dominate) the CO2 dynamics in these low flux environments and suggests that biological activity may be lower than previously thought. In this study, we aim to improve our understanding of CO2 dynamics (biotic and abiotic) in Antarctic Dry Valley soils using long-term automated measurements of soil CO2 surface flux and soil profile concentration at several sites, often at sub-diel frequency. We hypothesize that soil CO2 variations are driven primarily by environmental factors affecting CO2 solubility in soil solution, mainly temperature, and that these processes may even overprint biologic production in representative Dry Valley soils. Monitoring of all sites revealed only one likely biotic CO2 production event, lasting three weeks during the Austral summer and reaching fluxes of 0.4 µmol/m2/s. Under more typical low flux conditions (<0.10 µmol/m2/s) we observed a cyclical daily sink/source pattern consistent with CO2 solubility cycling that would not generally have been evident with normal synoptic afternoon sampling campaigns. Subsurface CO2 monitoring and a lab-controlled Antarctic soil simulation experiment confirmed that abiotic processes are capable of dominating soil CO2 variability. Diel temperature cycles crossing the freezing boundary revealed a dual abiotic cycle of solubility cycling and gas exclusion from ice formation observed only by high temporal frequency measurements (30 min). This work demonstrates a need for a numerical model to partition the dynamic abiotic processes underlying any biotic CO2 production in order to understand potential climate-change induced increases in microbial productivity in terrestrial Antarctica.

Occurrence of Cronobacter spp. in Dried Foods, Fresh Vegetables and Soil.

PubMed

Ueda, Shigeko

2017-01-01

　The present study surveyed the occurrence of Cronobacter spp. in dried foods including milk powder, spices and herbs and others, and fresh vegetables commercially available in markets, and ground soil materials for the agriculture. Cronobacter spp. were isolated from 15% of 33 spice and herb samples and 3% of 36 taste foods, and these were C. turicensis, C. malonaticus, C. sakazakii and C. dubliensis. Cronobacter spp. from fresh vegetables were detected in 12% of field vegetables and 13% of hydroponic vegetables. C. turicensis was prevalent in field vegetables, and C. malonaticus was in hydroponic ones. And, Cronobacter spp. in shredded vegetables were detected from 44% of 9 samples, and these were C. dubliensis, C. turicensis and C. sakazakii. Also, Cronobacter spp. in soil from rice field, vegetable field and sandpits were predominantly C. sakazakii and C. malonaticus.

NNSS Soils Monitoring: Plutonium Valley (CAU 366) FY2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikolich, George; Mizell, Steve; McCurdy, Greg

Desert Research Institute (DRI) is conducting a field assessment of the potential for contaminated soil transport from the Plutonium Valley Contamination Area (CA) as a result of wind transport and storm runoff in support of National Nuclear Security Administration (NNSA) efforts to complete regulatory closure of the contamination areas. The DRI work is intended to confirm the likely mechanism(s) of transport and determine the meteorological conditions that might cause movement of contaminated soils. The emphasis of the work is on collecting sediment transported by channelized storm runoff at the Plutonium Valley investigation sites. These data will inform closure plans thatmore » are being developed, which will facilitate the appropriate closure design and post-closure monitoring. In 2011, DRI installed two meteorological monitoring stations south (station #1) and north (station #2) of the Plutonium Valley CA and a runoff sediment sampling station within the CA. Temperature, wind speed, wind direction, relative humidity, precipitation, solar radiation, barometric pressure, soil temperature, and airborne particulate concentration are collected at both meteorological stations. The maximum, minimum, and average or total (as appropriate) for each of these parameters are recorded for each 10-minute interval. The sediment sampling station includes an automatically activated ISCO sampling pump with collection bottles for suspended sediment, which is activated when sufficient flow is present in the channel, and passive traps for bedload material that is transported down the channel during runoff events. This report presents data collected from these stations during fiscal year (FY) 2015.« less

Chlorinated and parent polycyclic aromatic hydrocarbons in environmental samples from an electronic waste recycling facility and a chemical industrial complex in China.

PubMed

Ma, Jing; Horii, Yuichi; Cheng, Jinping; Wang, Wenhua; Wu, Qian; Ohura, Takeshi; Kannan, Kurunthachalam

2009-02-01

Chlorinated polycyclic aromatic hydrocarbons (CIPAHs) are a class of halogenated contaminants found in the urban atmosphere; they have toxic potential similar to that of dioxins. Information on the sources of CIPAHs is limited. In this study, concentrations of 20 CIPAHs and 16 parent PAHs were measured in electronic wastes, workshop-floor dust, vegetation, and surface soil collected from the vicinity of an electronic waste (e-waste) recycling facility and in surface soil from a chemical industrial complex (comprising a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant), and agricultural areas in central and eastern China. High concentrations of SigmaCIPAHs were found in floor dust (mean, 103 ng/g dry wt), followed in order of decreasing concentration by leaves (87.5 ng/g drywt), electronic shredder waste (59.1 ng/g dry wt), and soil (26.8 ng/g dry wt) from an e-waste recycling facility in Taizhou. The mean concentration of SigmaCIPAHs in soil from the chemical industrial complex (88 ng/g dry wt) was approximately 3-fold higher than the concentration in soil from e-waste recycling facilities. The soils from e-waste sites and industrial areas contained mean concentrations of SigmaCIPAHs 2 to 3 orders of magnitude higher than the concentrations in agricultural soils (ND-0.76 ng/g), suggesting that e-waste recycling and chlorine-chemical industries are potential emission sources of CIPAHs. The profiles of CIPAHs in soil and dust were similar to a profile that has been reported previously for fly ash from municipal solid waste incinerators (6-CIBaP was the predominant compound), but the profiles in vegetation and electronic shredder waste were different from those found in fly ash. Concentrations of 16 parent PAHs were high (150-49,700 ng/g) in samples collected from the e-waste recycling facility. Significant correlation between SigmaCIPAH and SigmaPAH concentrations suggests that direct chlorination of parent PAHs is the major pathway of formation of CIPAHs during e-waste recycling operations. Dioxin-like toxic equivalency quotients (TEQs) for CIPAHs and PAHs in samples were calculated on the basis of relative potencies reported for CIPAHs and PAHs. The highest mean TEQ concentrations of CIPAHs (518 pg-TEQ/g) were found for workshop-floor dust, followed by leaves (361 pg-TEQ/g), electronic shredder waste (308 pg-TEQ/g), soil from the chemical industrial complex (146 pg-TEQ/g), and soil from the sites of the e-waste recycling facility (92.3 pg-TEQ/g). With one exception, the floor dust samples, the TEQ concentrations of CIPAHs found in multiple environmental matrices in this study were higher than the TEQ concentrations of PCDD/Fs in the same samples reported in our earlier study.

Water distribution at the root-soil interface: is there more water next to roots?

NASA Astrophysics Data System (ADS)

Carminati, A.; Moradi, A.; Oswald, S.; Vetterlein, D.; Weller, U.; Vogel, H.-J.

2009-04-01

Plants are big water movers and have a significant impact on soil water dynamics as well as on the global water cycle. Despite the relevance of root water uptake in terrestrial ecology, the movement of water from soil to roots still presents important open questions, e.g the following two. Which are the properties of the soil near the roots? And what effect do these properties have on soil plant water relations? Most models are based on brute-force spatial averaging of soil properties and assume that the bulk soil has the same properties as the rhizosphere. However, there is evidence in the literature that the rhizosphere has specific properties that may affect water and nutrient uptake (Young 1995, Gregory 2007). In order to investigate the rhizosphere hydraulic properties and their effect on soil plant water relations, we used neutron radiography and neutron tomography to image the water content distribution in soils during plant transpiration. Rectangular (quasi-2D) and cylindrical containers were filled with sandy soil and planted with lupins (Lupinus albus). Three weeks after planting, the samples were equilibrated at water potentials of -10 and 30 hPa and have been imaged for 5 days at intervals of 6 hours. At day 5 the samples were irrigated again via capillary rise and the water distribution was monitored for 4 more days. During the first day of the drying period, regions of water depletion formed around the central part of the tap root where first order laterals were present. As the soil dried up, the picture changed: instead of less water around the roots, as commonly supposed by models, we observed that more water was present around the lateral roots. Interestingly, these regions during drying were retaining high water content, but after irrigation remained markedly drier than the bulk soil. Our hypothesis is that high water content near roots during drying and lower water content during rewetting are explained by the presence of bio-polymers exuded by roots forming a hydrogel that consists of up to 99% water at very negative water potentials (Read et al. 1999). Thanks to its high water holding capacity, this hydrogel maintains a continuous hydraulic pathway across soil and roots for an extended period of time during drying. During rewetting it adversely affects water redistribution, like a storage that needs time to fill up again. These data show for the first time in situ the potential role of mucilage in controlling water dynamics in the rhizosphere and consequences for plant water extraction. Gregory P J, Roots, rhizosphere and soil: the route to a better understanding of soil science? European Journal of Soil Science, 57: 2-12, 2006. Read D P, Gregory P J, and Bell A E. Physical properties of axenic maize root mucilage. Plant and Soil, 211: 87-91, 1999. Young I M. Variation in moisture contents between bulk soil and the rhizosheath of wheat. New Phytologist, 130: 135-139, 1995.

Abiotic uptake of gases by organic soils

NASA Astrophysics Data System (ADS)

Smagin, A. V.

2007-12-01

Methodological and experimental studies of the abiotic uptake of gaseous substances by organic soils were performed. The static adsorption method of closed vessels for assessing the interaction of gases with the solid and liquid soil phases and the dynamic method of determining the sorption isotherms of gases by soils were analyzed. The theoretical substantiation of the methods and their practical implementations on the basis of a PGA-7 portable gas analyzer (Russia) were considered. Good agreement between the equilibrium sorption isotherms of the gases and the Langmuir model was revealed; for the real ranges of natural gas concentrations, this model can be reduced to the linear Henry equation. The limit values of the gas sorption (Langmuir monolayer capacity) are typical for dry samples; they vary from 670 4000 g/m3 for methane and oxygen to 20 000 25 000 g/m3 for carbon dioxide. The linear distribution coefficients of gases between the solid and gas phases of organic soils (Henry constants) are 8 18 units for poorly sorbed gases (O2, CH4) and 40 60 units for CO2. The kinetics of the chemicophysical uptake of gases by the soil studied is linear in character and obeys the relaxation kinetic model of the first order with the corresponding relaxation constants, which vary from 1 h -1 in wet samples to 10 h -1 in dry samples.

Mobility of arsenic and its compounds in soil and soil solution: the effect of soil pretreatment and extraction methods.

PubMed

Száková, J; Tlustos, P; Goessler, W; Frková, Z; Najmanová, J

2009-12-30

The effect of soil extraction procedures and/or sample pretreatment (drying, freezing of the soil sample) on the extractability of arsenic and its compounds was tested. In the first part, five extraction procedures were compared with following order of extractable arsenic portions: 2M HNO(3)>0.43 M CH(3)COOH>or=0.05 M EDTA>or=Mehlich III (0.2M CH(3)COOH+0.25 M NH(4)NO(3)+0.013 M HNO(3)+0.015 M NH(4)F+0.001 M EDTA) extraction>water). Additionally, two methods of soil solution sampling were compared, centrifugation of saturated soil and the use of suction cups. The results showed that different sample pretreatments including soil solution sampling could lead to different absolute values of mobile arsenic content in soils. However, the interpretation of the data can lead to similar conclusions as apparent from the comparison of the soil solution sampling methods (r=0.79). For determination of arsenic compounds mild extraction procedures (0.05 M (NH(4))(2)SO(4), 0.01 M CaCl(2), and water) and soil solution sampling using suction cups were compared. Regarding the real soil conditions the extraction of fresh samples and/or in situ collection of soil solution are preferred among the sample pretreatments and/or soil extraction procedures. However, chemical stabilization of the solutions should be allowed and included in the analytical procedures for determination of individual arsenic compounds.

Chemical migration during soil water retention curve evaluation.

PubMed

Pires, Luiz F; Villanueva, Felipe C A; Dias, Nivea M P; Bacchi, Osny O Santos; Reichardt, Klaus

2011-09-01

Wetting and drying (W-D) cycles can induce important elemental migrations in soils. The main purpose of this work was to study the possible existence of soil chemical elemental migrations in samples submitted to repeated W-D cycles during evaluations of soil water retention curve (SWRC). The experimental measurements were carried out by Atomic Absorption Spectrometry (AAS) for Ca(2+), Mg(2+) and K(+) on samples of three different Brazilian tropical soils (Geric Ferralsol, Eutric Nitosol and Rhodic Ferralsol). Results demonstrate an increase in the electrical conductivity of the water extracted from the samples and significant losses of Ca(2+), Mg(2+) and K(+) during the applications of up to nine W-D cycles. It was also observed differences in SWRC for all soils when samples submitted to the application of several W-D cycles were compared with samples not submitted to it. These differences occurred at the region of both structural and textural pores. A possible explanation for these results could be the soil chemical migration during the sequences of W-D cycles, which can affect the soil structure development.

Filtration stability of living brush mattresses at navigable waterways

NASA Astrophysics Data System (ADS)

Sokopp, Manuel

2017-04-01

According to the guidelines of the Federal Waterways Engineering and Research Institute in Germany, waterway construction buildings, which include soil bioengineering structures, must be stable against soil displacements. Therefore, willow brush mattresses were tested for their filtration stability in a specially developed process which is based on the testing of geotextiles and armourstones used for navigable waterway constructions. In March 2016 willow brush mattresses made of white (Salix alba L.) or basket willows (Salix viminalis L.) were planted in 16 sample boxes, each with a cross-section area of 30x30 cm. For the tests on filtration stability, the upper 20 cm of the box were separated and placed upside down into a device in which the sample box could be flowed through from below. When a water column of 50 cm above the sample was reached, the water outlet was opened so the water flowed through the sample in the opposite direction, thus simulating drawdown. By the measurements of the pressure sensors above and below the sample, the coefficient of permeability k of the rooted soil during drawdown could be calculated. After this hydropeaking cycle, the soil material that was rinsed out through the willow branches was collected, weighed after drying until weight constancy, and compared with the dry mass of the retained soil material to calculate the share of the total mass. These filtration stability tests were carried out directly after planting the sample boxes, as well as one, three and six months afterwards, each test series with four reruns per willow species. Over time, the increasing root penetration resulted in a significant reduction in the permeability and in more retained soil material.

BOREAS TE-2 NSA Soil Lab Data

NASA Technical Reports Server (NTRS)

Veldhuis, Hugo; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

2000-01-01

This data set contains the major soil properties of soil samples collected in 1994 at the tower flux sites in the Northern Study Area (NSA). The soil samples were collected by Hugo Veldhuis and his staff from the University of Manitoba. The mineral soil samples were largely analyzed by Barry Goetz, under the supervision of Dr. Harold Rostad at the University of Saskatchewan. The organic soil samples were largely analyzed by Peter Haluschak, under the supervision of Hugo Veldhuis at the Centre for Land and Biological Resources Research in Winnipeg, Manitoba. During the course of field investigation and mapping, selected surface and subsurface soil samples were collected for laboratory analysis. These samples were used as benchmark references for specific soil attributes in general soil characterization. Detailed soil sampling, description, and laboratory analysis were performed on selected modal soils to provide examples of common soil physical and chemical characteristics in the study area. The soil properties that were determined include soil horizon; dry soil color; pH; bulk density; total, organic, and inorganic carbon; electric conductivity; cation exchange capacity; exchangeable sodium, potassium, calcium, magnesium, and hydrogen; water content at 0.01, 0.033, and 1.5 MPascals; nitrogen; phosphorus: particle size distribution; texture; pH of the mineral soil and of the organic soil; extractable acid; and sulfur. These data are stored in ASCII text files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils.

PubMed

Wang, Zhongwen; Shan, Xiao-Quan; Zhang, Shuzhen

2002-03-01

Rhizosphere is a microbiosphere and has quite different chemical, physical and biological properties from bulk soils. A greenhouse experiment was performed to compare the difference of fractionation and bioavailability of trace elements Cr, Ni, Zn, Cu, Pb and Cd between rhizosphere soil and bulk soil. In the meantime, the influence of air-drying on the fractionation and bioavailability was also investigated by using wet soil sample as a control. Soils in a homemade rhizobox were divided into four zones: rhizosphere, near rhizosphere, near bulk soil and bulk soil zones, which was designated as S1, S2, S3 and S4. Elemental speciations were fractionated to water soluble, exchangeable and carbonate bound (B1), Fe-Mn oxide bound (B2), and organic and sulfide bound (B3) by a sequential extraction procedure. Speciation differences were observed for elements Cr, Ni, Zn, Cu, Pb and Cd between the rhizosphere and bulk soils, and between the air-dried and wet soils as well. The concentrations of all six heavy metals in fraction B1 followed the order of S2 > S3 > S1 > S4 and for B2, the order was S2 > S3 S4 > S1. For B3, the order was S1 > S3 S4 > S2, while for Cd the order was S2 > S3 approximately/= S4 > S1. The air-drying increased elemental concentration in fractions B1 and B2 by 20-50% and decreased in fraction B3 by about 20-100%. Correlation analysis also indicated that the bioavailability correlation coefficient of fraction B1 in rhizosphere wet soil to plants was better than that between either air-dried or nonrhizosphere soils. Therefore, application of rhizosphere wet soils should be recommended in the future study on the speciation analysis of trace elements in soils and bioavailability.

Persistent aryl hydrocarbon receptor inducers increase with altitude, and estrogen-like disrupters are low in soils of the Alps.

PubMed

Levy, Walkiria; Henkelmann, Bernhard; Bernhöft, Silke; Bovee, Toine; Buegger, Franz; Jakobi, Gert; Kirchner, Manfred; Bassan, Rodolfo; Kräuchi, Norbert; Moche, Wolfgang; Offenthaler, Ivo; Simončič, Primoz; Weiss, Peter; Schramm, Karl-Werner

2011-01-01

Soil samples from remote Alpine areas were analyzed for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and polychlorinated biphenyls by high-resolution gas chromatography/high-resolution gas spectrometry. Additionally, the EROD micro-assay and a genetically modified yeast estrogen bioassay were carried out to determine persistent aryl hydrocarbon receptors (AhR) and estrogen receptors (ER) agonists, respectively. Regarding the AhR agonists, the toxicity equivalents of analytical and EROD determined values were compared, targeting both altitude of samples and their soil organic content. The ratio between bioassay derived equivalents and analytical determinations suggested no significant contribution of unknown AhR inducers in these sampling sites and some antagonism in soils with relatively high PCB loading. More CYP1A1 expression was induced at the highest sites or about 1400-1500 m a.s.l. along the altitude profiles. Surprisingly, no clear tendencies with the soil organic content were found for dioxin-like compounds. Mean values obtained in the present study were for ER agonists, 2: 0.37±0.12ng 17ß-estradiol EQ g-1 dry soil [corrected] and 6.1 ± 4.2 pg TCDD-EQ g⁻¹ dry soil for AhR agonists. Low bioassay responses with a higher relative amount of ER disrupters than AhR inducers were detected,indicating the higher abundance of estrogen-like than persistent dioxin-like compounds in these forested areas [corrected].

Determination of organophosphate flame retardants in soil and fish using ultrasound-assisted extraction, solid-phase clean-up, and liquid chromatography with tandem mass spectrometry.

PubMed

Lorenzo, María; Campo, Julián; Picó, Yolanda

2018-03-22

A solid-liquid extraction method in combination with high-performance liquid chromatography and tandem mass spectrometry was developed and optimized for extraction and analysis of organophosphorus flame retardants in soil and fish. Methanol was chosen as the optimum extraction solvent, not only in terms of extraction efficiency, but also for its broader analyte coverage. The subsequent clean-up by solid-phase extraction is required to eliminate matrix coextractives and reduce matrix effects. Recoveries of the optimized method were 50-121% for soil and 47-123% for biota, both with high precision (RSDs <12% in soil and <23% in biota). The method limits of detection ranged from 0.06 to 0.20 ng/g dry weight and between 0.02 and 0.30 ng/g wet weight for soil and biota samples, respectively. However, samples with a high lipid content produce several problems as solid-phase extraction cartridge clogging that increase variability and analysis time. The method was successfully applied for the determination of organophosphorus flame retardants in soil and fish from L'Albufera Natural Park (Valencia, Spain). Target compounds were detected in all soil and fish samples with values varying from 13.8 to 89.7 ng/g dry weight and from 3.3 to 53.0 ng/g wet weight, respectively. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultra-trace determination of Strontium-90 in environmental soil samples from Qatar by collision/reaction cell-inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Meer, S. H.; Amr, M. A.; Helal, A.I.

Because of the very low level of {sup 90}Sr in the environmental soil samples and its determination by beta counting may take several weeks, we developed a procedure for ultra-trace determination of {sup 90}Sr using collision reaction cell-inductively coupled plasma tandem mass spectrometry (CRC-ICP-MS/MS, Agilent 8800). Soil samples were dried at 105 deg. C and then heated in a furnace at 550 deg. C to remove any organics present. 500 g of each soil samples were aliquoted into 2000 ml glass beakers. Each Soils samples were soaked in 2 ppm Sr solution carrier to allow determination of chemical yield. Themore » solid to liquid ratio was 1:1. Finally the soil samples were dried at 105 deg. C. Five hundred milliliters concentrated nitric acid and 250 ml hydrochloric acid volumes were added on 500 g soil samples. The samples were digested on hot plate at 80 deg. C to prevent spraying with continuous manual mixing. The leachate solution was separated. The solids were rinsed with 500 ml deionized water, warmed on a hot plate and the leachate plus previous leachate were filtered and the total volume was reduced to 500 ml by evaporation. Final leachate volume was transferred to a centrifuge tubes. The centrifuge tubes were centrifuged at 3,500 rpm for 10 min. The leachate was transferred to a 1 L beaker and heated on a hot plate to evaporate the leachate to dryness. The reside was re-dissolved in 100 ml of 2% HNO{sub 3} and reduced by evaporation to 10 mL. The solution was measured directly by CRC-ICP-MS/MS by setting the first quadruple analyzer to m/z 90 and introducing oxygen gas into the reaction cell for elimination isobar interference from zirconium-90. The method was validated by measurements of standard reference materials and applied on environmental soil samples. The overall time requirement for the measurement of strontium-90 by CRC-ICP-MS/MS is 2 days, significantly shorter than any radioanalytical protocol currently available. (authors)« less

Production and Characterization of Nanosilica from Bagasse Through Biosynthesis Using Lactobacilus bulgaricus.

PubMed

Rahmawati, Nanda Yuli; Harisna, Azza Hanief; Khoirunnisa, Wulida; Yasvinawati, Niarisandi; Sumitro, Sutiman Bambang

2016-06-01

Bagasse has a potential as natural resource of nanosilica. Nanosilica biosynthetic production method is better than chemical or physical methods. The aim of this study is to determine the potential of Lactobacillus bulgaricus in nanosilica synthesis, the effect of the long incubation, and the effect of freeze drying to the nanosilica quality. The method consists of two steps. The first is performing biosynthesize using bagasse and Lactobacillus bulgaricus in dark place with temperature of 37 degress C for the period of 24 hours, 48 hours, and 72 hours. The second is analyzing particles and chemical of nanosilica characterization using Fourier Transformer Infrared Spectroscopy (FTIR), Particle Size Analyzer (PSA), X-ray Diffraction (XRD), some microscopes namely stereo, fluorescence, polarizing, Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX). The results show that nanosilica has spherical shaped, amorphous, and able to fluoresce when exposed by UV. The average size of particles are 104.6 nm in the 24 hours length incubated, 67.3 nm in the 48 hours length incubation, and 30.5 nm in the 72 hours length incubation. Samples using freeze drying have more complex and smaller structure than samples using air drying. The lengths of incubation influence the size and shape of nanosilica. Samples using freeze drying enable change the soil structure, and has beneficiary effect to improve soil fertility, as nanofertilizer. Whereas, the samples using air drying may use for glass or biofilm materials.

Micro-structure and Swelling Behaviour of Compacted Clayey Soils: A Quantitative Approach

NASA Astrophysics Data System (ADS)

Ferber, Valéry; Auriol, Jean-Claude; David, Jean-Pierre

In this paper, the clay aggregate volume and inter-aggregate volume in compacted clayey soils are quantified, on the basis of simple hypothesis, using only their water content and dry density. Swelling tests on a highly plastic clay are then interpreted by describing the influence of the inter-aggregate volume before swelling on the total volume of samples after swelling. This approach leads to a linear relation between these latter parameters. Based on these results, a description of the evolution of the microstructure due to imbibition can be proposed. Moreover, this approach enables a general quantification of the influence of initial water content and dry density on the swelling behaviour of compacted clayey soils.

The repeated drying-wetting and freezing-thawing cycles affect only the active pool of soil organic matter

NASA Astrophysics Data System (ADS)

Semenov, Vyacheslav; Zinyakova, Natalya; Tulina, Anastasiya

2016-04-01

The decrease in the content of soil organic carbon, particularly in active form, is one of the major problems of the 21st century, which is closely related to the disturbance of the biogeochemical carbon cycle and to the increase in the emission of carbon dioxide into the atmosphere. The main reasons for the SOM losses are the surplus of the SOM active pool losses due to mineralization, erosion, and infiltration over the input of fresh organic matter to the soil, as well as the changes in the soil conditions and processes due to natural and anthropogenic disturbing impacts. Experiments were carried out with mixed samples from the upper layers of soddy-podzolic soil, gray forest soil, and typical chernozems. Soil samples as controls were incubated after wetting for 150 days. The dynamics and cumulative production of C-CO2 under stable temperature (22°C) and moisture conditions were determined; the initial content of potentially mineralizable organic matter (C0) in the soil at the beginning of the incubation was then calculated to use these data as the control. Other soil samples were exposed in flasks to the following successive treatments: wetting →incubation → freezing → thawing → incubation →drying. Six repeated cycles of disturbing impacts were performed for 140 days of the experiment. After six cycles, the soil samples were incubated under stable temperature and moisture conditions for 150 days. The wetting of dried soils and the thawing of frozen soils are accompanied by the pulsed dynamics of the C-CO2 production with an abrupt increase in the rate of the C-CO2 emission within several days by 2.7-12.4 and 1.6-2.7 times, respectively, compared to the stable incubation conditions. The rate of the C-CO2 production pulses under each subsequent impact decreased compared to the preceding one similarly for all studied soils, which could be due to the depletion in potentially mineralizable soil organic matter (C0). The cumulative extra C-CO2 production by soils of the natural lands during six cycles of disturbing impacts composed 21-40% of that by soils incubated under stable conditions; the corresponding values for the cultivated soils, including soil under the continuous bare fallow, were in the range of 45-82%. The structure of the active organic matter pool in uncultivated soils after six incubation cycles became similar to those for soils under the continuous bare fallow, as well as under farming agrocenoses. Following from the obtained results that the organic matter mobilized by disturbing impacts was predominantly mineralized in arable soils with an initially low C0 content, while a part of the mobilized organic matter was stabilized in untreated soils with the high initial C0 content. This work was supported by RSF. Project number 14-14-00625

Metal-resistant rhizobacteria isolates improve Mucuna deeringiana phytoextraction capacity in multi-metal contaminated soils from a gold mining area.

PubMed

Boechat, Cácio Luiz; Giovanella, Patricia; Amorim, Magno Batista; de Sá, Enilson Luiz Saccol; de Oliveira Camargo, Flávio Anastácio

2017-01-01

Phytoremediation consists of biological techniques for heavy metal remediation, which include exploring the genetic package of vegetable species to remove heavy metals from the environment. The goals of this study were to investigate heavy metal and bioaugmentation effects on growth and nutrient uptake by Mucuna deeringiana; to determine the metal translocation factor and bioconcentration factor and provide insight for using native bacteria to enhance heavy metal accumulation. The experiment was conducted under greenhouse conditions using a 2 × 4 factorial scheme with highly and slightly contaminated soil samples and inoculating M. deeringiana with three highly lead (Pb +2 )-resistant bacteria Kluyvera intermedia (Ki), Klebsiella oxytoca (Ko), and Citrobacter murliniae (Cm) isolated from the rhizosphere of native plants identified as Senecio brasiliensis (Spreng.) Less., Senecio leptolobus DC., and Baccharis trimera (Less) DC., respectively. The increased heavy metal concentrations in soil samples do not decrease the root dry mass of M. deeringiana, concerning the number and dry weight of nodules. The shoot dry mass is reduced by the increasing concentration of heavy metals in soil associated with Kluyvera intermedia and Klebsiella oxytoca bacteria. The number of nodules is affected by heavy metals associated with Citrobacter murliniae bacteria. The bacteria K. intermedia, C. murliniae, and K. oxytoca increase the lead and cadmium available in the soil and enhanced metal uptake by Mucuna deeringiana. The M. deeringiana specie has characteristics that make it hyperaccumulate copper and zinc. The translocation and bioconcentration factors for M. deeringiana characterize it as a promising candidate to phytostabilize multi-metal contaminated soils.

Virus movement in soil columns flooded with secondary sewage effluent.

PubMed Central

Lance, J C; Gerba, C P; Melnick, J L

1976-01-01

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles. PMID:185960

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

NASA Technical Reports Server (NTRS)

Reyes, A. L.

1975-01-01

A series of experiments was conducted to determine the dry heat resistance of microorganisms in soil obtained from Denver Colorado, Pasadena California, Kennedy Space Center Florida, and Cincinnati Ohio. The results of the KSC terminal sterilization cycle experiment are given in graphs. The average number of viable organisms per m1 was calculated for 18 replicate soil samples for each sample area and points plotted equivalent to 30 hr exposure at 112 C. The result showed a reduction of 3 logs from the initial population for both KSC and Cincinnati soil samples. Results from other areas are given in graphs.

Mars-like soils in the Atacama Desert, Chile, and the dry limit of microbial life.

PubMed

Navarro-González, Rafael; Rainey, Fred A; Molina, Paola; Bagaley, Danielle R; Hollen, Becky J; de la Rosa, José; Small, Alanna M; Quinn, Richard C; Grunthaner, Frank J; Cáceres, Luis; Gomez-Silva, Benito; McKay, Christopher P

2003-11-07

The Viking missions showed the martian soil to be lifeless and depleted in organic material and indicated the presence of one or more reactive oxidants. Here we report the presence of Mars-like soils in the extreme arid region of the Atacama Desert. Samples from this region had organic species only at trace levels and extremely low levels of culturable bacteria. Two samples from the extreme arid region were tested for DNA and none was recovered. Incubation experiments, patterned after the Viking labeled-release experiment but with separate biological and nonbiological isomers, show active decomposition of organic species in these soils by nonbiological processes.

Use of Ultrasonic Technology for Soil Moisture Measurement

NASA Technical Reports Server (NTRS)

Choi, J.; Metzl, R.; Aggarwal, M. D.; Belisle, W.; Coleman, T.

1997-01-01

In an effort to improve existing soil moisture measurement techniques or find new techniques using physics principles, a new technique is presented in this paper using ultrasonic techniques. It has been found that ultrasonic velocity changes as the moisture content changes. Preliminary values of velocities are 676.1 m/s in dry soil and 356.8 m/s in 100% moist soils. Intermediate values can be calibrated to give exact values for the moisture content in an unknown sample.

Source, impact and removal of malodour from soiled clothing.

PubMed

Denawaka, Chamila J; Fowlis, Ian A; Dean, John R

2016-03-18

Static headspace--multi-capillary column--gas chromatography--ion mobility spectrometry (SHS-MCC-GC-IMS) has been applied to the analysis of malodour compounds from soiled clothing (socks and T-shirts), pre- and post washing, at low temperature (20°C). Six volatile compounds (VCs) (i.e. butyric acid, dimethyl disulfide, dimethyl trisulfide, 2-heptanone, 2-nonanone and 2-octanone) were identified. After sensory evaluation of soiled garments they were subjected to laundering with non-perfumed washing powder. The efficiency of the laundering process was evaluated by determining the reduction of each detected volatile compound (VC) post-wash (damp) for socks and T-shirts; VC concentration reductions of between 16 and 100% were noted, irrespective of sample type. Additionally the T-shirt study considered the change in VC concentration post-wash (dry) i.e. after the drying process at ambient temperature. Overall VC concentration reductions of between 25 and 98% were noted for T-shirt samples pre-wash to post-wash (dry). Finally, a potential biochemical metabolic pathway for the formation of malodour compounds associated with bacteria in axillary sweat is proposed. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Monitoring aggregate disintegration with laser diffraction: A tool for studying soils as sediments

NASA Astrophysics Data System (ADS)

Mason, Joseph; Kasmerchak, Chase; Liang, Mengyu

2016-04-01

One of the more important characteristics of soil that becomes hillslope, fluvial, or aeolian sediment is the presences of aggregates, which disintegrate at varying rates and to varying degrees during transport. Laser diffraction particle size analyzers allow monitoring of aggregate disintegration as a sample of soil or sediment suspended in water is circulated continuously through the measurement cell (Bieganowski et al., 2010, Clay Minerals 45-23-34; Mason et al., Catena 87:107-118). Mason et al. (2011) applied this approach to aeolian sedimentary aggregates (e.g. clay pellets eroded from dry lakebeds), immersing dry samples in DI water and circulating them through a Malvern Mastersizer 2000 particle size analyzer for three hours while repeated size distribution (SD) measurements were made. A final measurement was made after sonication and treatment with Na-metaphosphate. In that study, most samples approached a steady SD within three hours, which included both primary mineral grains and persistent aggregates. The disintegration process could be modeled with a first-order rate law representing the disintegration of a single population of aggregates. A wide range of model parameters were observed among the samples studied, and it was suggested that they could be useful in predicting the behavior of these aggregates, under rainfall impact and during slopewash or fluvial transport. Addition of Ca++ to the suspension altered aggregate behavior in some but not all cases. We applied the same method to dry, unground material from upper horizons of soils sampled along a bioclimatic gradient in northern Minnesota, USA, all formed in lithologically similar glacigenic sediment. These ranged from Alfisols (Luvisols) formed under forest since the last deglaciation, to Alfisols under forest that more recently replaced grassland, and Mollisols (Chernozems) that formed entirely under grassland vegetation. Few of these soil samples approached a steady SD within three hours, and modeling aggregate disintegration required the assumption of at least two aggregate populations. Upper horizons of soils formed under grassland displayed relatively slow disintegration throughout the procedure, with a large proportion of aggregates remaining after three hours. E horizons from forest soils, with low organic matter (OM) and clay content, displayed rapid early distintegration of a large portion of the aggregates, followed by much slower breakdown of the remainder (i.e. the two populations modeled had very different rate constants). OM content is clearly the overriding control on aggregate behavior, but we are also exploring effects of clay content and mineralogy, cation chemistry, and other factors. The differences in aggregate behavior are likely to be relevant to transport and deposition of sediment eroded from these soils, and possibly to the transport of OM or nutrients with eroded soil. We hope to incorporate this method into ongoing field studies of soil erosion with colleagues at UW-Madison.

Micaceous Soil Strength And Permeability Improvement Induced By Microbacteria From Vegetable Waste

NASA Astrophysics Data System (ADS)

Omar, R. C.; Roslan, R.; Baharuddin, I. N. Z.; Hanafiah, M. I. M.

2016-11-01

Green technology method using vegetable waste are introduced in this paper for improvement of phyllite residual soil from UNITEN, Campus. Residual soil from phyllite are known as micaceous soils and it give problem in managing the stability of the slope especially in wet and extensively dry seasons. Micaceous soil are collected using tube sampler technique and mixed with liquid contain microorganism from fermented vegetable waste name as vege-grout to form remolded sample. The remolded sample are classify as 15.0%, 17.5%, 20.00% and 22.5% based on different incremental percentages of vege-grout. The curing time for the sample are 7, 14, 21, 28, and 35 days before the tests were conducted. Observation of the effect of treatment shows 20.0% of liquid contain Bacillus pasteurii and Bacillus Subtilis with 21 days curing time is the optimum value in strengthening the soil and improve the permeability.

Microbially-mediated carbon fluxes vary with landscape position in two erodible, intensively managed agricultural landscapes

NASA Astrophysics Data System (ADS)

Fine, A.; Wilson, C. G.; Papanicolaou, T.; Schaeffer, S. M.

2017-12-01

The balance between loss of C to the atmosphere, and the accumulation of soil organic matter is directly controlled by soil microorganisms. A key driver of microbial activity is soil moisture, but it is unclear how microbial C cycling responds to spatiotemporal shifts in hydrological conditions across a heterogeneous, dynamic landscape. We explored the relationship between soil wetness and biogeochemical cycling along landscape positions in two sloping fields of the Intensively Managed Landscape Critical Zone Observatory (IML-CZO) in Iowa, USA. Soils were collected (0-5 cm, 5-10 cm) from four positions (crest, shoulder, backslope, toeslope) along three transects identified as primary flow paths for runoff and sediment. Samples were incubated for 7 days and analyzed pre- and post-incubation for extractable dissolved organic C (DOC), microbial biomass C (MBC), microbial respiration (C-resp), and inorganic N. At both sites, field moisture, MBC, and CUE 0-5 cm increased from summit to toeslope, whereas CUE 5-10 cm decreased. The steeper and drier of the two fields (field 1) showed corresponding increases in C-resp and NO3, but decreases in DOC, moving downslope; the opposite trends were observed in the less erodible, wetter field 2. Comparing the two toeslopes (0-5 cm), field 2 had a larger labile C (DOC + MBC) pool (3.1 mg C g-1 dry soil) than field 1 (2.7 mg g-1 dry soil), but C-resp of field 1 was lower (53 and 42 ug g-1 dry soil for fields 1 and 2, respectively). No differences in MBC between depths were observed in field 1, but in field 2, MBC 5-10 cm (0.6 and 0.7 mg g-1 dry soil at crest and toeslope, respectively) was always less than MBC 0-5 cm (0.9 mg g-1 dry soil). Our findings indicate that wet, poorly drained soil conditions (such as those in lower landscape positions and at depth) decrease microbial activity and allow DOC to accumulate. Despite the relatively enhanced depositional environment of field 1, the low levels of DOC and high C-resp and MBC indicate more suitable conditions for aerobic respiration.

Long Term and High Frequency Non-Destructive Monitoring of Soil Water Stable Isotope Compositions in the Laboratory

NASA Astrophysics Data System (ADS)

Rothfuss, Y.; Merz, S.; Pohlmeier, A. J.; Vereecken, H.; Brueggemann, N.

2014-12-01

The fate and dynamics of water stable isotopologues (1H2H16O and 1H218O) are currently well implemented into physically based Soil-Vegetation-Atmosphere Transfer (SVAT) models (e.g. Hydrus 1D, SiSPAT-I, Soil-Litter iso, TOUGHREACT). However, contrary to other state variables (e.g., water content and tension) that can be monitored over long periods (e.g., by time-domain reflectometry, capacitive sensing, tensiometry or micro-psychrometry), water stable isotope compositions (δ2H and δ18O) are analyzed following destructive sampling, and thus are available only at a given time. Thus, there are important discrepancies in time resolution between soil water and stable isotope information which greatly limit the insight potential of the latter. Recently however, a technique based on direct infrared laser absorption spectroscopy was developed that allows simultaneous and direct measurements of δ2H and δ18O in water vapor. Here, we present a non-destructive method for monitoring soil liquid δ2H and δ18O by sampling and measuring water vapor equilibrated with soil water using gas-permeable polypropylene tubing and a Cavity Ring-Down laser Spectrometer (CRDS). An acrylic glass column (d=11 cm, h=60 cm) was (i) equipped with temperature and soil water probes in addition to gas-permeable tubing sections at eight different depths, (ii) filled with pure quartz sand, (iii) saturated from the bottom, and (iv) installed on weighing balances and let dry for 250 days. Each day, soil vapor δ2H and δ18O were measured for each depth by purging the soil water vapor sampled in the tubing sections with dry air and analyzing it with a CRDS. Soil liquid water δ2H and δ18O were then inferred from the values measured in the vapor. The experimental setup allowed following the evolution of the soil water δ2H and δ18O profile, which developed as a result of isotope convective capillary rise and back-diffusion of the stable isotope excess at the soil surface due to fractionating soil evaporation, with unprecedentedly high temporal resolution. As the soil dried out, we could show for the first time the increasing influence of the depleted ambient water vapor on the enriched liquid water close to the soil surface. Finally, the obtained data was simulated using the fully coupled 1D isotope-enabled SVAT model SiSPAT-Isotope.

Relationship soil-water-plant after the dry season in dry Mediterranean areas

NASA Astrophysics Data System (ADS)

Hueso-González, P.; Jiménez-Donaire, V.; Ruiz-Sinoga, J. D.

2012-04-01

Preliminary studies have determined the existence of a pluviometric gradient around Mediterranean system, which varies from 240 to 1 100 mm mean annual rainfall. This gradient has an incidence in the physical, chemical and hydrological properties in soils with the same litology. Empiric results conclude that humid eco-geomorphological systems are controlled by biotic processes, whereas in arid eco-geomorphological systems, are abiotic factors which have more importance in soil degradation processes. The study area of the present work is located in Málaga (Andalusia, Spain), in the southern part of the Natural Park "Sierra Tejeda, Almijara y Alhama". There, the mean annual temperature is around 18 °C and the mean rainfall is 650 mm. Predominant vegetation corresponds to the termomediterranean serie Smilaci Mauritanicae-Querceto Rotundifoliae Sigmetum, typical of basic soils. The aim of this study is to analyse the immediate hydrological response of the soil under different vegetation covers, through the analysis of certain properties, all this, under subhumid ombrotipe. A random choice of ten representative plants has been done. These plants, with different sizes, were located in the same Southern slope. The soil samples were taken right beside the plant log, and also within a distance of 0.4 to 1 metre from them, depending on the plant size. The sampling was carried out between the end of the dry season and the beginning of the wet one, after a 20% of the mean annual rainfall had rained. The physical, chemical and hydrological analyzes -both in the field and the laboratory- were: exchange-base, total carbon, cation exchange capacity, soil infiltration capacity, salt content, hydrophobia, organic matter, soil organic carbon, total nitrogen, wetting profile in bared soil, wetting profile under vegetation cover (shrubland), and p.H. Literature reveals that rainfall affects significantly the edafogenetic factors, regarding the pluviometric gradient level. In the present study, from a 20% accumulated rainfall of the total mean, not considerable incidences can be found. Furthermore, after the dry season, rainfall event higher than 0.5 mm are necessary in order to observe changes in soil wetting profile. However, for intense rainfall episodes, the hydrological soil response -observe by its wetting profile- in bare soil is 24 hours, and 48 hours in soils vegetation cover. Secondly, soil hydraulic conductivity - measured with a minidisc infiltrometer at different distances from the selected plants- shows that soil infiltration capacity does not follow a determined patter. This could be due to the significant stony character of the studied area soil/presence of stones in of the studied area soil. Finally, not major differences regarding soil organic matter have been observed, either at species level or temporal level, from the selected plant.

Phylogeography of microbial phototrophs in the dry valleys of the high Himalayas and Antarctica.

PubMed

Schmidt, S K; Lynch, R C; King, A J; Karki, D; Robeson, M S; Nagy, L; Williams, M W; Mitter, M S; Freeman, K R

2011-03-07

High-elevation valleys in dry areas of the Himalayas are among the most extreme, yet least explored environments on Earth. These barren, rocky valleys are subjected to year-round temperature fluctuations across the freezing point and very low availability of water and nutrients, causing previous workers to hypothesize that no photoautotrophic life (primary producers) exists in these locations. However, there has been no work using modern biogeochemical or culture-independent molecular methods to test the hypothesis that photoautotrophs are absent from high Himalayan soil systems. Here, we show that although microbial biomass levels are as low as those of the Dry Valleys of Antarctica, there are abundant microbial photoautotrophs, displaying unexpected phylogenetic diversity, in barren soils from just below the permanent ice line of the central Himalayas. Furthermore, we discovered that one of the dominant algal clades from the high Himalayas also contains the dominant algae in culture-independent surveys of both soil and ice samples from the Dry Valleys of Antarctica, revealing an unexpected link between these environmentally similar but geographically very distant systems. Phylogenetic and biogeographic analyses demonstrated that although this algal clade is globally distributed to other high-altitude and high-latitude soils, it shows significant genetic isolation by geographical distance patterns, indicating local adaptation and perhaps speciation in each region. Our results are the first to demonstrate the remarkable similarities of microbial life of arid soils of Antarctica and the high Himalayas. Our findings are a starting point for future comparative studies of the dry valleys of the Himalayas and Antarctica that will yield new insights into the cold and dry limits to life on Earth.

The status and importance of crude protein and macro minerals in native pastures growing on Vertisols of the central highlands of Ethiopia.

PubMed

Gizachew, Lemma; Smit, G N

2012-01-01

The effects of pasture management, season and soil nutrient status on crude protein (CP) and macro mineral concentration of native pasture was studied in the Vertisol areas of the central Ethiopian highland. Soil and herbage samples from 18 continuously grazed (CG) and 12 seasonally grazed (SG) pasture sites were analyzed for N, P, Ca, Mg, K and Na. Soil and dry season CG pasture samples were collected in January and February 2001 (dry season: November-February), while wet season CG and SG pasture samples were collected during September 2001 (wet season: April-October). The Potassium concentration (2.55%) of mixed herbage samples from SG pasture exceeded the K values (1.80%) from CG pasture (P < 0.01). Significant (P < 0.01) differences of CP and macro minerals concentrations were noted among forage species. The mean CP and K concentrations of herbage from CG pasture were higher (P < 0.01) during the wet than during the dry season (5.97 and 1.80% vs. 3.18 and 0.79%), while the opposite was true for Ca (0.49% vs. 0.61%) (P < 0.05). Regarding soil macro minerals and the corresponding herbage macro mineral concentrations, significant (P < 0.05) but inconsistent correlations were found for Ca, P, Mg and Na. The results suggest that pasture management, season and to some extend soil nutrient status, can affect herbage CP and macro mineral composition. The levels of CP in CG pasture and that of P and Na in both CG and SG pastures may fall below the requirements of grazing livestock. Resting at critical stages of the growth cycle of the forage species encouraged the recovery of desirable species. For this reason resting of pasture can contribute significantly to the quality of the native pastures of the Vertisols of the central Ethiopian highlands and should be encouraged. Copyright © 2011 Elsevier Ltd. All rights reserved.

Risk assessment of Cd polluted paddy soils in the industrial and township areas in Hunan, Southern China.

PubMed

Wang, Meie; Chen, Weiping; Peng, Chi

2016-02-01

Cadmium (Cd) contamination in rice in Youxian, Hunan, China is a major environmental health concern. In order to reveal the Cd contamination in rice and paddy soils and the health risks to the population consuming the local rice grain, field surveys were conducted in eight towns in Youxian, China. The Cd contents of paddy soils averaged 0.228-1.91 mg kg(-1), 90% exceeding the allowable limit of 0.3 mg kg(-1) stipulated by the China Soil Environmental Quality Standards. Low average pH values (for air dried oxidized soils) ranging from 4.98 to 6.02 in paddy soil were also found. More than seventy percent (39 of 53) of the grain samples exceeded the maximum safe concentration of Cd, 0.2 mg kg(-1) on a dry weight basis. Considering the high consumption of local rice (339 g capita(-1) DW d(-1)) and Cd levels measured, dietary ingestion of 78% of the sampled rice grains would have adverse health risks because the intake exposure of Cd was greater than the JECFA recommended exposures, 0.8 µg Cd BW kg(-1) day(-1) or 25 µg Cd BW kg(-1) month(-1). Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of soil moisture on sunflower oil extraction of polycyclic aromatic hydrocarbons from a manufactured gas plant soil.

PubMed

Gong, Zongqiang; Wilke, B-M; Alef, Kassem; Li, Peijun

2005-05-01

The influence of soil moisture on efficiency of sunflower oil extraction of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil was investigated. The PAH-contaminated soil was collected from a manufactured gas plant (MGP) site in Berlin, Germany. Half of the soil was air-dried, and the other half was kept as field-moist soil. Batch experiments were performed using air-dried and field-moist soils, and sunflower oil was used as extractant at oil/soil ratios of 2:1 and 1:1 (v/m). The experimental data were fitted to a first-order empirical model to describe mass-transfer profiles of the PAHs. Column extraction experiments were also conducted. Field-moist and air-dried soils in the column were extracted using sunflower oil at an oil/soil ratio of 2:1. In the batch experiments, PAHs were more rapidly extracted from air-dried soil than from field-moist soil. Removal rate of total PAH increased 23% at oil/soil ratio of 1:1 and 15.5% at oil/soil ratio of 2:1 after the soil was air dried. The most favorable conditions for batch extraction were air-dried soil, with an oil/soil ratio of 2:1. In the column experiments, the removal rate of total PAH from air-dried soil was 30.7% higher than that from field-moist soil. For field-moist soil, extraction efficiencies of the batch extraction (67.2% and 81.5%) were better than that for column extraction (65.6%). However, this difference between the two methods became less significant for the air-dried soil, with a total removal rate of 96.3% for column extraction and 90.2% and 97% for batch extractions. A mass-balance test was carried out for analytical quality assurance. The results of both batch and column experiments indicated that drying the soil increased efficiency of extraction of PAHs from the MGP soil.

Effects of fines content on hydraulic conductivity and morphology of laterite soil as hydraulic barrier

NASA Astrophysics Data System (ADS)

Bello Yamusa, Yamusa; Yunus, Nor Zurairahetty Mohd; Ahmad, Kamarudin; Rahman, Norhan Abd; Sa'ari, Radzuan

2018-03-01

Laterite soil was investigated to find out the effects of fines content and to identify the micro-structural and molecular characteristics to evaluate its potentiality as a compacted soil landfill liner material. Tests were carried out on natural soil and reconstituted soil by dry weight of soil samples to determine the physical and engineering properties of the soil. All tests were carried out on the samples by adopting the British Standard 1377:1990. The possible mechanisms that contributed to the clay mineralogy were analyzed using spectroscopic and microscopic techniques such as field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and X-ray diffractometry (XRD). The laterite soil was found to contain kaolinite as the major clay minerals. A minimum of 50% fines content of laterite soil met the required result for hydraulic barriers in waste containment facilities.

Response of selected microoganisms to experimental planetary environments

NASA Technical Reports Server (NTRS)

Foster, T. L.

1975-01-01

A microbial population profile of mixed Cape Canaveral soil samples is presented. During this investigation a few organisms were isolated which exhibit the ability to grow at 3 C, 32 C, and 55 C. Growth curves are shown for three of these isolates, one of which grows extremely well at all three temperatures. Also included are studies dealing with growth of soil populations at zero and subzero temperatures. Results indicate growth at 0 C and -5 C, but not at 15 C or -65 C. The effect of storage temperature on dry soil is presented, and results show that psychrophilic populations decrease when soil is stored at room temperature, but do not decrease when soil is stored at -65 C. Results of an experiment with the simulated Martian environment are presented and indicate that nonsporeforming rods, sporeforming rods, and cocci can reproduce in the simulated environment when nutrients and moisture are supplied. The sporeforming rods are the predominant suvivors when dry soil is subjected to this environment.

Spatial variability of soils in a seasonally dry tropical forest

NASA Astrophysics Data System (ADS)

Pulla, Sandeep; Riotte, Jean; Suresh, Hebbalalu; Dattaraja, Handanakere; Sukumar, Raman

2016-04-01

Soil structures communities of plants and soil organisms in tropical forests. Understanding the controls of soil spatial variability can therefore potentially inform efforts towards forest restoration. We studied the relationship between soils and lithology, topography, vegetation and fire in a seasonally dry tropical forest in southern India. We extensively sampled soil (available nutrients, Al, pH, and moisture), rocks, relief, woody vegetation, and spatial variation in fire burn frequency in a permanent 50-ha plot. Lower elevation soils tended to be less moist and were depleted in several nutrients and clay. The availability of several nutrients was, in turn, linked to whole-rock chemical composition differences since some lithologies were associated with higher elevations, while the others tended to dominate lower elevations. We suggest that local-scale topography in this region has been shaped by the spatial distribution of lithologies, which differ in their susceptibility to weathering. Nitrogen availability was uncorrelated with the presence of trees belonging to Fabaceae, a family associated with N-fixing species. No effect of burning on soil parameters could be discerned at this scale.

Americium-241 in surface soil associated with the Hanford site and vicinity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, K.R.; Gilbert, R.O.; Gano, K.A.

1981-05-01

Various kinds of surface soil samples were collected and analyzed for Americium-241 (/sup 241/Am) to examine the feasibility of improving soil sample data for the Hanford Surface Environmental Surveillance Program. Results do not indicate that a major improvement would occur if procedures were changed from the current practices. Conclusions from this study are somewhat tempered by the very low levels of /sup 241/Am (< 0.10 pCi/g dry weight) detected in surface soil samples and by the fact that statistical significance depended on the type of statistical tests used. In general, the average concentration of /sup 241/Am in soil crust (0more » to 1.0 cm deep) was greater than the corresponding subsurface layer (1.0 to 2.5 cm deep), and the average concentration of /sup 241/Am in some onsite samples collected near the PUREX facility was greater than comparable samples collected 60 km upwind at an offsite location.« less

Dissolved organic C and N pools in soils amended with composted and thermally-dried sludge as affected by soil tillage systems and sampling depth

NASA Astrophysics Data System (ADS)

García-Gil, Juan Carlos; Soler-Rovira, Pedro Angel; García López de Sa, Esther; Polo, Alfredo

2013-04-01

Soil tillage practices exert a significant influence on the dynamic of soluble organic C and N pools, affecting nutrient cycling in agricultural systems by enhancing its mineralization through microbial activities or stabilization in soil microaggregates, which contribute to mitigate greenhouse gases emissions. The objective of the present research was to determine the influence of three different soil management systems (moldboard plowing, chisel and no-tillage) and the application of composted sludge (CS) and thermally-dried sewage sludge (TSS) obtained from wastewater treatment processes on dissolved organic C (water-soluble organic C -WSOC-, carbohydrates, phenolic compounds) and soluble N (total-N, NH4+, NO3-) pools in a long-term field experiment (27 years) conducted on a sandy-loam soil at the experimental station "La Higueruela" (40° 03'N, 4° 24'W) under semi-arid conditions. Both organic amendments were applied at a rate of 30 tonnes per hectare prior to tillage practices. Unamended soils were used as control for each tillage system. Soil sampling was performed two months after tillage practices at the following depths for each treatment: 0-10 cm, 10-20 cm and 20-30 cm. Results obtained for unamended soils showed that no-tillage management increased total-N, NH4+ and NO3- contents at the 0-10 cm depth samples, meanwhile WSC and carbohydrates contents were larger at 20-30 cm depth samples in both moldboard and no-tillage plots. CS and TSS-amended soils presented a general increase in soluble C and N compounds, being significantly higher in TSS-amended soils, as TSS contains a great amount of labile organic C and N substrates due to the lack of stabilization treatment. TSS-amended soils under no-tillage and chisel plowing showed larger N, NH4+ and NO3- content at the 0-10 cm samples, meanwhile moldboard management exhibited larger NH4+ and NO3- content at 10-20 and 20-30 cm samples, possibly due to the incorporation of TSS at deeper depths (20-40 cm). CS and TSS-amended soils in no-tillage system showed the largest content of organic C pools at 0-10 cm depth samples due to less soil disturbance and the input of organic substrates with CS and TSS on soil surface. CS and TSS-amended soils under chisel plowing exhibited similar contents of soluble organic C pools at 10-20 and 20-30 cm depth samples and only TSS-amended soils increased significantly WSOC content at 0-10 cm samples. Similarly, contents of WSOC and carbohydrates in moldboard plowing were distributed more uniformly throughout the soil profile due to the turnover of soil and CS and TSS amendments into the plow layer. Acknowledgements: this research was supported by the Spanish CICYT, Project no. CTM2011-25557.

Organophosphate pesticide in agricultural soils from the Yangtze River Delta of China: concentration, distribution, and risk assessment.

PubMed

Pan, Lili; Sun, Jianteng; Li, Zhiheng; Zhan, Yu; Xu, Shen; Zhu, Lizhong

2018-01-01

Organophosphorus pesticides (OPPs) are used worldwide and pose great risks to human health. However, information on their presence in agricultural soils at regional scale and the associated risks is limited. In this study, an extensive investigation on agricultural soils was conducted throughout the Yangtze River Delta (YRD) of China to reveal the status of OPP pollution. The total concentrations of the nine OPPs ranged from <3.0 to 521 ng g -1 dry weight, with a mean of 64.7 ng g -1 dry weight and a detection rate of 93 %. Dimethoate was found to be the primary compound, followed by methyl parathion and parathion. The highest concentrations of OPPs were found in Jiangsu province due to the intensive agricultural activities. The pollution of OPPs is also highly associated with the land use types. The lower concentrations of OPPs found in vegetable fields could be attributed to their easy photodegradation and hydrolysis in aerobic soils. There was no significant difference in microbial communities among the sample sites, indicating that OPPs in agricultural soils of the YRD region cause negligible effects on microbiota. The risks of OPPs in the soils to human health were further evaluated. The hazard indexes in all the soil samples were below 1, suggesting absence of non-cancer risks. This study provides valuable information for a better understanding of the pollution status of OPPs in agricultural soils and a scientific basis for soil quality assessments.

Rhizosphere biophysics and root water uptake

NASA Astrophysics Data System (ADS)

Carminati, Andrea; Zarebanadkouki, Mohsen; Ahmed, Mutez A.; Passioura, John

2016-04-01

The flow of water into the roots and the (putative) presence of a large resistance at the root-soil interface have attracted the attention of plant and soil scientists for decades. Such resistance has been attributed to a partial contact between roots and soil, large gradients in soil matric potential around the roots, or accumulation of solutes at the root surface creating a negative osmotic potential. Our hypothesis is that roots are capable of altering the biophysical properties of the soil around the roots, the rhizosphere, facilitating root water uptake in dry soils. In particular, we expect that root hairs and mucilage optimally connect the roots to the soil maintaining the hydraulic continuity across the rhizosphere. Using a pressure chamber apparatus we measured the relation between transpiration rate and the water potential difference between soil and leaf xylem during drying cycles in barley mutants with and without root hairs. The samples were grown in well structured soils. At low soil moistures and high transpiration rates, large drops in water potential developed around the roots. These drops in water potential recovered very slowly, even after transpiration was severely decreased. The drops in water potential were much bigger in barley mutants without root hairs. These mutants failed to sustain high transpiration rates in dry conditions. To explain the nature of such drops in water potential across the rhizosphere we performed high resolution neutron tomography of the rhizosphere of the barleys with and without root hairs growing in the same soil described above. The tomograms suggested that the hydraulic contact between the soil structures was the highest resistance for the water flow in dry conditions. The tomograms also indicate that root hairs and mucilage improved the hydraulic contact between roots and soil structures. At high transpiration rates and low water contents, roots extracted water from the rhizosphere, while the bulk soil, due its low unsaturated conductivity, failed to compensate root water uptake. We conclude that root hairs are functional to increase the contact area between the roots and the soil structures and mucilage maintains wet the soil region between root hairs. These observations demonstrate the importance of the biophysical processes in the rhizosphere in modulating root water uptake.

Effects of soil water saturation on sampling equilibrium and kinetics of selected polycyclic aromatic hydrocarbons.

PubMed

Kim, Pil-Gon; Roh, Ji-Yeon; Hong, Yongseok; Kwon, Jung-Hwan

2017-10-01

Passive sampling can be applied for measuring the freely dissolved concentration of hydrophobic organic chemicals (HOCs) in soil pore water. When using passive samplers under field conditions, however, there are factors that might affect passive sampling equilibrium and kinetics, such as soil water saturation. To determine the effects of soil water saturation on passive sampling, the equilibrium and kinetics of passive sampling were evaluated by observing changes in the distribution coefficient between sampler and soil (K sampler/soil ) and the uptake rate constant (k u ) at various soil water saturations. Polydimethylsiloxane (PDMS) passive samplers were deployed into artificial soils spiked with seven selected polycyclic aromatic hydrocarbons (PAHs). In dry soil (0% water saturation), both K sampler/soil and k u values were much lower than those in wet soils likely due to the contribution of adsorption of PAHs onto soil mineral surfaces and the conformational changes in soil organic matter. For high molecular weight PAHs (chrysene, benzo[a]pyrene, and dibenzo[a,h]anthracene), both K sampler/soil and k u values increased with increasing soil water saturation, whereas they decreased with increasing soil water saturation for low molecular weight PAHs (phenanthrene, anthracene, fluoranthene, and pyrene). Changes in the sorption capacity of soil organic matter with soil water content would be the main cause of the changes in passive sampling equilibrium. Henry's law constant could explain the different behaviors in uptake kinetics of the selected PAHs. The results of this study would be helpful when passive samplers are deployed under various soil water saturations. Copyright © 2017 Elsevier Ltd. All rights reserved.

The dose-dependent influence of zinc and cadmium contamination of soil on their uptake and glucosinolate content in white cabbage (Brassica oleracea var. capitata f. alba).

PubMed

Kusznierewicz, Barbara; Bączek-Kwinta, Renata; Bartoszek, Agnieszka; Piekarska, Anna; Huk, Anna; Manikowska, Anna; Antonkiewicz, Jacek; Namieśnik, Jacek; Konieczka, Piotr

2012-11-01

The relationship between the ability to accumulate heavy metals (represented by Cd and Zn) and to synthesize bioactive compounds (represented by glucosinolates [GLS]) was investigated in two cabbage cultivars. Plants were grown in the greenhouse of a phytotron under controlled conditions in soils spiked with two different Zn or Cd concentrations. The measurements of Cd and Zn contents in soil and cabbage (leaf) samples were performed by atomic absorption spectroscopy, whereas GLS levels in cabbage were determined by high-performance liquid chromatography. The ranges of metal contents in soil were 80 to 450 mg/kg dry weight for Zn and 0.3 to 30 mg/kg dry weight for Cd, whereas the levels of accumulated Zn and Cd in cabbage amounted to 15 to 130 and 0.02 to 3 mg/kg dry weight, respectively. After initial symptoms of toxicity, during a later stage of growth, the plants exhibited very good tolerance to both metals. Enhanced biosynthesis of GLS was observed in a dose-dependent manner following exposure to the heavy metals. The GLS content in Zn-exposed cabbage rose from 3.2 to 12 µmol/g dry weight, and the corresponding values for Cd-treated plants were 3.5 to 10 µmol/g dry weight. Thus, the increased soil contamination by metals caused greater accumulation in cabbage, as well as stimulation of GLS biosynthesis. The results obtained point to the high phytoremediation and biofumigation potential of white cabbage. Copyright © 2012 SETAC.

Phthalate esters contamination in soil and plants on agricultural land near an electronic waste recycling site.

PubMed

Ma, Ting Ting; Christie, Peter; Luo, Yong Ming; Teng, Ying

2013-08-01

The accumulation of phthalic acid esters (PAEs) in soil and plants in agricultural land near an electronic waste recycling site in east China has become a great threat to the neighboring environmental quality and human health. Soil and plant samples collected from land under different utilization, including fallow plots, vegetable plots, plots with alfalfa (Medicago sativa L.) as green manure, fallow plots under long-term flooding and fallow plots under alternating wet and dry periods, together with plant samples from relative plots were analyzed for six PAE compounds nominated as prior pollutants by USEPA. In the determined samples, the concentrations of six target PAE pollutants ranged from 0.31-2.39 mg/kg in soil to 1.81-5.77 mg/kg in various plants (dry weight/DW), and their bioconcentration factors (BCFs) ranged from 5.8 to 17.9. Health risk assessments were conducted on target PAEs, known as typical environmental estrogen analogs, based on their accumulation in the edible parts of vegetables. Preliminary risk assessment to human health from soil and daily vegetable intake indicated that DEHP may present a high-exposure risk on all ages of the population in the area by soil ingestion or vegetable consumption. The potential damage that the target PAE compounds may pose to human health should be taken into account in further comprehensive risk assessments in e-waste recycling sites areas. Moreover, alfalfa removed substantial amounts of PAEs from the soil, and its use can be considered a good strategy for in situ remediation of PAEs.

Leaching of heavy metals and alkylphenolic compounds from fresh and dried sewage sludge.

PubMed

Milinovic, Jelena; Vidal, Miquel; Lacorte, Silvia; Rigol, Anna

2014-02-01

Reusing sewage sludge as a soil fertiliser has become a common alternative to disposal. Although this practice has a few benefits, it may contribute to the medium- and long-term contamination of the trophic chain because sewage sludge may contain heavy metals and organic contaminants. As the leaching of contaminants may depend on the sludge pre-treatment, the leaching of heavy metals (Cu, Ni, Pb, Zn and Cr) and alkylphenolic compounds (APCs) (octylphenol (OP), nonylphenol (NP), nonylphenol-mono-ethoxylate (NP1EO)) was investigated in five fresh and 40 °C dried sewage sludge samples from north-eastern Spain. FT-IR analyses and full-scan GC-MS chromatograms showed that sludge drying changed the nature of organic compounds leading to changes in their solubility. Moreover, sludge drying led to a higher relative contribution of dissolved organic carbon than the particulate organic carbon in the leachates. Leaching of Pb, Zn and Cr was below 5 % in both fresh and dried sludge samples, whereas Cu and Ni leached at rates up to 12 and 43 %, respectively, in some of the dried sludge samples. The leaching yields of OP, NP and NP1EO ranged from 1.3 to 35 % for fresh samples, but they decreased from 0.8 to 3.4 % in dried samples. The decrease in the leachability of APCs observed in dried sludge samples might be attributed to the fact that these compounds are associated with particulate organic matter, with significantly lower concentration or even absent in dried sludge than in fresh sludge samples. Therefore, it is recommended to dry the sludge before its disposal.

Constitutive Soil Properties for Cuddeback Lake, California and Carson Sink, Nevada

NASA Technical Reports Server (NTRS)

Thomas, Michael A.; Chitty, Daniel E.; Gildea, Martin L.; T'Kindt, Casey M.

2008-01-01

Accurate soil models are required for numerical simulations of land landings for the Orion Crew Exploration Vehicle. This report provides constitutive material modeling properties for four soil models from two dry lakebeds in the western United States. The four soil models are based on mechanical and compressive behavior observed during geotechnical laboratory testing of remolded soil samples from the lakebeds. The test specimens were reconstituted to measured in situ density and moisture content. Tests included: triaxial compression, hydrostatic compression, and uniaxial strain. A fit to the triaxial test results defines the strength envelope. Hydrostatic and uniaxial tests define the compressibility. The constitutive properties are presented in the format of LS-DYNA Material Model 5: Soil and Foam. However, the laboratory test data provided can be used to construct other material models. The four soil models are intended to be specific only to the two lakebeds discussed in the report. The Cuddeback A and B models represent the softest and hardest soils at Cuddeback Lake. The Carson Sink Wet and Dry models represent different seasonal conditions. It is possible to approximate other clay soils with these models, but the results would be unverified without geotechnical tests to confirm similar soil behavior.

Zeolite Formation and Weathering Processes in Dry Valleys of Antartica: Martian Analogs

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Wentworth, S. J.; McKay, D. S.; Socki, R. A.

2004-01-01

Terrestrial weathering processes in cold-desert climates such as the Dry Valleys of Antarctica may provide an excellent analog to chemical weathering and diagenesis of soils on Mars. Detailed studies of soil development and the chemical and mineralogical alterations occurring within soil columns in Wright Valley, Antarctica show incredible complexity in the upper meter of soil. Previous workers noted the ice-free Dry Valleys are the best terrestrial approximations to contemporary Mars. Images returned from the Pathfinder and Spirit landers show similarities to surfaces observed within the Dry Valleys. Similarities to Mars that exist in these valleys are: mean temperatures always below freezing (-20 C), no rainfall, sparse snowfall-rapidly removed by sublimation, desiccating winds, diurnal freeze-thaw cycles (even during daylight hours), low humidity, oxidative environment, relatively high solar radiation and low magnetic fields . The Dry Valley soils contain irregular distributions and low abundances of soil microorganisms that are somewhat unusual on Earth. Physical processes-such as sand abrasion-are dominant mechanisms of rock weathering in Antarctica. However, chemical weathering is also an important process even in such extreme climates. For example, ionic migration occurs even in frozen soils along liquid films on individual soil particles. It has also been shown that water with liquid-like properties is present in soils at temperatures on the order of approx.-80 C and it has been observed that the percentage of oxidized iron increases with increasing soil age and enrichments in oxidized iron occurs toward the surface. The presence of evaporates is evident and appear similar to "evaporite sites" within the Pathfinder and Spirit sites. Evaporites indicate ionic migration and chemical activity even in the permanently frozen zone. The presence of evaporates indicates that chemical weathering of rocks and possibly soils has been active. Authogenic zeolites have been identified within the soil columns because they are fragile; i.e. they are euhedral, unabraded, and unfractured, strongly suggesting in situ formation. Their presence in Antarctic samples is another indication that diagenic processes are active in cold-desert environments. The presence of zeolites, and other clays along with halites, sulfates, carbonates, and hydrates are to be expected within the soil columns on Mars at the Gusev and Isidis Planitia regions. The presence of such water-bearing minerals beneath the surface supplies one of the requirements to support biological activity on Mars.

Mercury in forest mushrooms and topsoil from the Yunnan highlands and the subalpine region of the Minya Konka summit in the Eastern Tibetan Plateau.

PubMed

Falandysz, Jerzy; Saba, Martyna; Liu, Hong-Gao; Li, Tao; Wang, Ji-Peng; Wiejak, Anna; Zhang, Ji; Wang, Yuan-Zhong; Zhang, Dan

2016-12-01

This study aimed to investigate and discuss the occurrence and accumulation of mercury in the fruiting bodies of wild-growing fungi (Macromycetes) collected from montane forests in two regions of southwestern China with differences in soil geochemistry, climate and geographical conditions. Fungal mycelia in soils of the subalpine region of the Minya Konka (Gongga Mountain) in Sichuan and in the highlands of Yunnan efficiently accumulated mercury in fruiting bodies (mushrooms). The examined sites in Yunnan with highly mineralized red and yellow soils showed Hg contents ranging from 0.066 to 0.28 mg kg -1 dry biomass (db) which is roughly similar to the results obtained for samples collected from sites with dark soils relatively rich in organic matter from a remote, the subalpine region of Minya Konka. Due to the remoteness of the subalpine section of Minya Konka, as well as its elevation and climate, airborne mercury from long-range transport could be deposited preferentially on the topsoil and the Hg levels determined in soil samples taken beneath the fruiting bodies were up to 0.48 mg kg -1 dry matter. In Yunnan, with polymetallic soils (Circum-Pacific Mercuriferous Belt), Amanita mushrooms showed mercury in caps of fruiting bodies of up to 7.3 mg kg -1 dry biomass. Geogenic Hg from the mercuriferous belt seems to be the overriding source of mercury accumulated in mushrooms foraged in the regions of Yunnan, while long-range atmospheric transport and subsequent deposition are the mercury sources for specimens foraged in the region of Minya Konka.

Directional optical transmission through a sand layer: a preliminary laboratory experiment

NASA Astrophysics Data System (ADS)

Tian, Jia; Philpot, William D.

2017-10-01

Given the importance of penetration of light in the soil for seed germination, soil warming, and the photolytic degradation of pesticides, directional transmission of thin sand samples are studied in this paper under both dry and saturated conditions. The detector views upward through a glass-bottom sample holder, filled to 3 or 4 mm with a coarse, translucent, quartz sand sample. Transmission through the samples was measured as the illumination zenith angle moved from 0 to 70° in 5° intervals. In the most cases, transmission decreased monotonically, but slowly with increasing illumination angle at all wavelengths. A peak in transmission only appeared at 0° illumination for the low bulk density, dry sample at 3 mm depth. The 0° peak disappeared when the sample was wetted, when the bulk density increased, or when the depth of the sample increased, which indicates that the radiation transmitting through a sand layer can be diffused thoroughly with a millimeters-thin sand layer. For the saturated samples, water influences light transmission in contrasting ways in shorter and longer wavelength. Transmission increased in the VNIR when saturated relative to dry, while transmission decreased sharply after 1300 nm, with spectral absorption features characteristic of water absorption. In VNIR region, water absorption is low and the low relative index of refraction enhanced transmission through sand sample. In contrast, water absorption became dominant at longer wavelengths region leading to the strongly reduced transmission.

Dry Deposition of Polycyclic Aromatic Hydrocarbons (PAHs) at a Suburban Site in Beijing, China

NASA Astrophysics Data System (ADS)

Zhang, Xincheng; Wang, Weiyu; Zhu, Xianlei

2017-04-01

A great amount of polycyclic aromatic hydrocarbons (PAHs) have been generated by industrial production, waste incineration and landfill, traffic and road dust etc. They are emitted into atmosphere and afterwards enter into water body and soil through deposition, resulting in wide distribution of PAHs in environment. However, the dry deposition of PAHs from atmosphere has not been well studied, especially in the aspects of its characteristics, environmental and health effects, sources and mechanism. This study measured PAHs dry deposition in the northwest suburban area of Beijing. Dry deposition samples (i.e. dustfall samples) were collected at the sampling site located in China University of Petroleum - Beijing in 2012-2016. And PAHs in the samples were determined by GC/MS. The dry deposition flux of 16 US EPA priority PAHs (ΣPAH16) was 2.58 μg/(m^2·d), which was lower than those in other regions of North China. Its seasonal variability was more significant than annual variability (p<0.05) and the seasonal pattern was winter > spring > autumn > summer. The amount of ΣPAH16 removed from the atmosphere by dry deposition process accounted for only 1.2% of their emissions, indicating that the atmosphere self-purification capacity was quite limited and emission reduction measures would play a key role in controlling PAHs air pollution. However, PAHs dry deposition would deteriorate soil quality since the content of ΣPAH16 in dustfall was 1-2 orders of magnitude higher than that in soil in the same area. Dermal exposure resulting from PAHs dry deposition was not the major route. The sources of PAHs dry deposition varied with seasons. The profile and specific ratios of PAHs showed that in winter, domestic coal combustion was the main source of PAHs with the contribution up to 77%; in spring and summer, the impact of coal combustion decreased and the contribution of vehicle exhaust increased to 30% - 45%; in fall, in addition to coal combustion and vehicle exhaust, the impact of biomass burning was observed with the contribution of 20% - 40%. After the implementation of Beijing 2013 Clean Air Action Plan, the proportion of low-ring PAHs, tracers of coal combustion, decreased, reflecting the positive impact of policy. The mechanism of PAHs dry deposition mechanism was different from that of airborne particulate matter (PM). Dry deposition of PAHs in PM with aerodynamic diameter <0.69μm and >10.2μm was responsible for, respectively, 45% and 23% of PAHs in dustfall, and caused seasonal variability of PAHs dry deposition. Key words: dry deposition; PAHs; suburban area; source; environmental effects; health risk Acknowledgments: The study has been supported by Beijing Excellent Talents Project of the year of 2012 (No.2012D009051000001) and by National Science Foundation (No.41175102) *Corresponding author: Xianlei Zhu e-mail: zhuxl@cup.edu.cn)

Critical soil bulk density for soybean growth in Oxisols

NASA Astrophysics Data System (ADS)

Keisuke Sato, Michel; Veras de Lima, Herdjania; Oliveira, Pedro Daniel de; Rodrigues, Sueli

2015-10-01

The aim of this study was to evaluate the critical soil bulk density from the soil penetration resistance measurements for soybean root growth in Brazilian Amazon Oxisols. The experiment was carried out in a greenhouse using disturbed soil samples collected from the northwest of Para characterized by different texture. The treatments consisted of a range of soil bulk densities for each soil textural class. Three pots were used for soybean growth of and two for the soil penetration resistance curve. From the fitted model, the critical soil bulk density was determined considering the penetration resistance values of 2 and 3 MPa. After sixty days, plants were cut and root length, dry mass of root, and dry mass of shoots were determined. At higher bulk densities, the increase in soil water content decreased the penetration resistance, allowing unrestricted growth of soybean roots. Regardless of soil texture, the penetration resistance of 2 and 3 MPa had a slight effect on root growth in soil moisture at field capacity and a reduction of 50% in the soybean root growth was achieved at critical soil bulk density of 1.82, 1.75, 1.51, and 1.45 Mg m-3 for the sandy loam, sandy clay loam, clayey, and very clayey soil.

Propagules of arbuscular mycorrhizal fungi in a secondary dry forest of Oaxaca, Mexico.

PubMed

Guadarrama, Patricia; Castillo-Argüero, Silvia; Ramos-Zapata, José A; Camargo-Ricalde, Sara L; Alvarez-Sánchez, Javier

2008-03-01

Plant cover loss due to changes in land use promotes a decrease in spore diversity of arbuscular mycorrhizal fungi (AMF), viable mycelium and, therefore, in AMF colonization, this has an influence in community diversity and, as a consequence, in its recovery. To evaluate different AMF propagules, nine plots in a tropical dry forest with secondary vegetation were selected: 0, 1, 7, 10, 14, 18, 22, 25, and 27 years after abandonment in Nizanda, Oaxaca, Mexico. The secondary vegetation with different stages of development is a consequence of slash and burn agriculture, and posterior abandonment. Soil samples (six per plot) were collected and percentage of AMF field colonization, extrarradical mycelium, viable spore density, infectivity and most probable number (MPN) ofAMF propagules were quantified through a bioassay. Means for field colonization ranged between 40% and 70%, mean of total mycelium length was 15.7 +/- 1.88 mg(-1) dry soil, with significant differences between plots; however, more than 40% of extracted mycelium was not viable, between 60 and 456 spores in 100 g of dry soil were recorded, but more than 64% showed some kind of damage. Infectivity values fluctuated between 20% and 50%, while MPN showed a mean value of 85.42 +/- 44.17 propagules (100 g dry soil). We conclude that secondary communities generated by elimination of vegetation with agricultural purposes in a dry forest in Nizanda do not show elimination of propagules, probably as a consequence of the low input agriculture practices in this area, which may encourage natural regeneration.

Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model

NASA Astrophysics Data System (ADS)

Shellito, Peter J.; Small, Eric E.; Livneh, Ben

2018-03-01

Drydown periods that follow precipitation events provide an opportunity to assess controls on soil evaporation on a continental scale. We use SMAP (Soil Moisture Active Passive) observations and Noah simulations from drydown periods to quantify the role of soil moisture, potential evaporation, vegetation cover, and soil texture on soil drying rates. Rates are determined using finite differences over intervals of 1 to 3 days. In the Noah model, the drying rates are a good approximation of direct soil evaporation rates, and our work suggests that SMAP-observed drying is also predominantly affected by direct soil evaporation. Data cover the domain of the North American Land Data Assimilation System Phase 2 and span the first 1.8 years of SMAP's operation. Drying of surface soil moisture observed by SMAP is faster than that simulated by Noah. SMAP drying is fastest when surface soil moisture levels are high, potential evaporation is high, and when vegetation cover is low. Soil texture plays a minor role in SMAP drying rates. Noah simulations show similar responses to soil moisture and potential evaporation, but vegetation has a minimal effect and soil texture has a much larger effect compared to SMAP. When drying rates are normalized by potential evaporation, SMAP observations and Noah simulations both show that increases in vegetation cover lead to decreases in evaporative efficiency from the surface soil. However, the magnitude of this effect simulated by Noah is much weaker than that determined from SMAP observations.

Effect of soil type and moisture availability on the foraging behavior of the Formosan subterranean termite (Isoptera: Rhinotermitidae).

PubMed

Cornelius, Mary L; Osbrink, Weste L A

2010-06-01

This study examined the influence of soil type and moisture availability on termite foraging behavior. Physical properties of the soil affected both tunneling behavior and shelter tube construction. Termites tunneled through sand faster than top soil and clay. In containers with top soil and clay, termites built shelter tubes on the sides of the containers. In containers with sand, termites built shelter tubes directly into the air and covered the sides of the container with a layer of sand. The interaction of soil type and moisture availability affected termite movement, feeding, and survival. In assays with moist soils, termites were more likely to aggregate in top soil over potting soil and peat moss. However, termites were more likely to move into containers with dry peat moss and potting soil than containers with dry sand and clay. Termites were also significantly more likely to move into containers with dry potting soil than dry top soil. In the assay with dry soils, termite mortality was high even though termites were able to travel freely between moist sand and dry soil, possibly due to desiccation caused by contact with dry soil. Evaporation from potting soil and peat moss resulted in significant mortality, whereas termites were able to retain enough moisture in top soil, sand, and clay to survive for 25 d. The interaction of soil type and moisture availability influences the distribution of foraging termites in microhabitats.

Spatial distribution of hydroxylamine and its role in aerobic N2O formation in a Norway spruce forest soil

NASA Astrophysics Data System (ADS)

Liu, S.; Weymann, D.; Gottselig, N.; Wiekenkamp, I.; Vereecken, H.; Brueggemann, N.

2014-12-01

Hydroxylamine (HA) as a crucial intermediate in the microbial oxidation of ammonium to nitrite (nitrification) is a potential precursor of abiotic N2O formation in the soil. However, the determination of HA concentration in natural soil samples has not been reported until now. Here, we determined the HA concentrations in organic (Oh) and mineral (Ah) layers of 135 soil samples collected from a spruce forest (Wüstebach, Eifel National Park, Germany) using a novel approach, based on the fast extraction of HA from the soil at a pH of 1.7, the oxidation of HA to N2O with Fe3+, and the analysis of produced N2O using gas chromatography (GC). Meanwhile, N2O emission rates were determined by means of aerobic laboratory incubations of 3-g soil in 22-mL vials. Subsequently, the spatial distribution of soil HA concentrations and N2O emission rates in the Oh and Ah layers of the whole sampling area were analyzed using a geostatistical approach. The correlations among soil HA, N2O emission rate, pH, soil C, N, Fe, Mn and soil water content (SWC) were further explored. The HA concentrations ranged from 0.3-44.6 μg N kg-1 dry soil and 0.02-16.2 μg N kg-1 dry soil in the Oh and the Ah layer, respectively. The spatial distribution of HA was similar in both layers, with substantial spatial variability dependent on soil type, tree density and distance to a stream. For example, HA concentration was greater at locations with a thick litter layer or at locations close to the stream. The average N2O emission rate in the Oh layer was 0.38 μg N kg-1 dry soil h-1, 10-fold larger than in the Ah layer. Interestingly, N2O emission rate exhibited high correlation with soil HA content in the Oh (R2 = 0.65, p < 0.01) and Ah (R2 = 0.45, p < 0.05) layer. The results demonstrated that HA is a crucial component for aerobic N2O formation and emission in spruce forest soils. Moreover, HA concentration was negatively correlated with pH and positively correlated with SWC in the Oh layer, while positively correlated with C and N as well as NO3- content in the Ah layer. Mn content was the most important factor for HA recovery at the specific extraction conditions. Further studies should focus on the effects of soil organic matter, Mn content, and pH on the production of N2O from HA under aerobic conditions.

Mercury content of Illinois soils

USGS Publications Warehouse

Dreher, G.B.; Follmer, L.R.

2004-01-01

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

BOREAS TE-1 SSA Soil Lab Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Knapp, David E. (Editor); Nerbas, Tim; Anderson, Darwin

2000-01-01

This data set was collected by TE-1 to provide a set of soil properties for BOREAS investigators in the SSA. The soil samples were collected at sets of soil pits in 1993 and 1994. Each set of soil pits was in the vicinity of one of the five flux towers in the BOREAS SSA. The collected soil samples were sent to a lab, where the major soil properties were determined. These properties include, but are not limited to, soil horizon; dry soil color; pH; bulk density; total, organic, and inorganic carbon; electric conductivity; cation exchange capacity; exchangeable sodium, potassium, calcium, magnesium, and hydrogen; water content at 0.01, 0.033, and 1.5 MPascals; nitrogen; phosphorus; particle size distribution; texture; pH of the mineral soil and of the organic soil; extractable acid; and sulfur. The data are stored in tabular ASCII text files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Soil moisture and soil temperature variability among three plant communities in a High Arctic Lake Basin

NASA Astrophysics Data System (ADS)

Davis, M. L.; Konkel, J.; Welker, J. M.; Schaeffer, S. M.

2017-12-01

Soil moisture and soil temperature are critical to plant community distribution and soil carbon cycle processes in High Arctic tundra. As environmental drivers of soil biochemical processes, the predictability of soil moisture and soil temperature by vegetation zone in High Arctic landscapes has significant implications for the use of satellite imagery and vegetation distribution maps to estimate of soil gas flux rates. During the 2017 growing season, we monitored soil moisture and soil temperature weekly at 48 sites in dry tundra, moist tundra, and wet grassland vegetation zones in a High Arctic lake basin. Soil temperature in all three communities reflected fluctuations in air temperature throughout the season. Mean soil temperature was highest in the dry tundra community at 10.5±0.6ºC, however, did not differ between moist tundra and wet grassland communities (2.7±0.6 and 3.1±0.5ºC, respectively). Mean volumetric soil moisture differed significantly among all three plant communities with the lowest and highest soil moisture measured in the dry tundra and wet grassland (30±1.2 and 65±2.7%), respectively. For all three communities, soil moisture was highest during the early season snow melt. Soil moisture in wet grassland remained high with no significant change throughout the season, while significant drying occurred in dry tundra. The most significant change in soil moisture was measured in moist tundra, ranging from 61 to 35%. Our results show different gradients in soil moisture variability within each plant community where: 1) soil moisture was lowest in dry tundra with little change, 2) highest in wet grassland with negligible change, and 3) variable in moist tundra which slowly dried but remained moist. Consistently high soil moisture in wet grassland restricts this plant community to areas with no significant drying during summer. The moist tundra occupies the intermediary areas between wet grassland and dry tundra and experiences the widest range of soil moisture variability. As climate projections predict wetter summers in the High Arctic, expansion of areas with seasonally inundated soils and increased soil moisture variability could result in an expansion of wet grassland and moist tundra communities with a commensurate decrease in dry tundra area.

Combination of a Fast Cleanup Procedure and a DR-CALUX® Bioassay for Dioxin Surveillance in Taiwanese Soils

PubMed Central

Lin, Ding-Yan; Lee, Yi-Pin; Li, Chiu-Ping; Chi, Kai-Hsien; Liang, Bo-Wei P.; Liu, Wen-Yao; Wang, Chih-Cheng; Lin, Susana; Chen, Ting-Chien; Yeh, Kuei-Jyum C.; Hsu, Ping-Chi; Hsu, Yi-Chyun; Chao, How-Ran; Tsou, Tsui-Chun

2014-01-01

Our goal was to determine dioxin levels in 800 soil samples collected from Taiwan. An in vitro DR-CALUX® assay was carried out with the help of an automated Soxhlet system and fast cleanup column. The mean dioxin level of 800 soil samples was 36.0 pg-bioanalytical equivalents (BEQs)/g dry weight (d.w.). Soil dioxin-BEQs were higher in northern Taiwan (61.8 pg-BEQ/g d.w.) than in central, southern, and eastern Taiwan (22.2, 24.9, and 7.80 pg-BEQ/g d.w., respectively). Analysis of multiple linear regression models identified four major predictors of dioxin-BEQs including soil sampling location (β = 0.097, p < 0.001), land use (β = 0.065, p < 0.001), soil brightness (β = 0.170, p < 0.001), and soil moisture (β = 0.051, p = 0.020), with adjusted R2 = 0.947 (p < 0.001) (n = 662). An univariate logistic regression analysis with the cut-off point of 33.4 pg-BEQ/g d.w. showed significant odds ratios (ORs) for soil sampling location (OR = 2.43, p < 0.001), land use (OR = 1.47, p < 0.001), and soil brightness (OR = 2.83, p = 0.009). In conclusion, four variables, including soil sampling location, land use, soil brightness, and soil moisture, may be related to soil-dioxin contamination. Soil samples collected in northern Taiwan, and especially in Bade City, soils near industrial areas, and soils with darker color may contain higher dioxin-BEQ levels. PMID:24806195

Quantitative Estimation of the Viability of Toxoplasma gondii Oocysts in Soil

PubMed Central

Villena, Isabelle; Dardé, Marie-Laure; Aubert, Dominique; Geers, Régine; Dupuis, Emilie; Marnef, Francine; Poulle, Marie-Lazarine; Gotteland, Cécile; Dumètre, Aurélien

2012-01-01

Toxoplasma gondii oocysts spread in the environment are an important source of toxoplasmosis for humans and animal species. Although the life expectancy of oocysts has been studied through the infectivity of inoculated soil samples, the survival dynamics of oocysts in the environment are poorly documented. The aim of this study was to quantify oocyst viability in soil over time under two rain conditions. Oocysts were placed in 54 sentinel chambers containing soil and 18 sealed water tubes, all settled in two containers filled with soil. Containers were watered to simulate rain levels of arid and wet climates and kept at stable temperature for 21.5 months. At nine sampling dates during this period, we sampled six chambers and two water tubes. Three methods were used to measure oocyst viability: microscopic counting, quantitative PCR (qPCR), and mouse inoculation. In parallel, oocysts were kept refrigerated during the same period to analyze their detectability over time. Microscopic counting, qPCR, and mouse inoculation all showed decreasing values over time and highly significant differences between the decreases under dry and damp conditions. The proportion of oocysts surviving after 100 days was estimated to be 7.4% (95% confidence interval [95% CI] = 5.1, 10.8) under dry conditions and 43.7% (5% CI = 35.6, 53.5) under damp conditions. The detectability of oocysts by qPCR over time decreased by 0.5 cycle threshold per 100 days. Finally, a strong correlation between qPCR results and the dose infecting 50% of mice was found; thus, qPCR results may be used as an estimate of the infectivity of soil samples. PMID:22582074

Land application of mine water causes minimal uranium loss offsite in the wet-dry tropics: Ranger Uranium Mine, Northern Territory, Australia.

PubMed

Mumtaz, Saqib; Streten, Claire; Parry, David L; McGuinness, Keith A; Lu, Ping; Gibb, Karen S

2015-11-01

Ranger Uranium Mine (RUM) is situated in the wet-dry tropics of Northern Australia. Land application (irrigation) of stockpile (ore and waste) runoff water to natural woodland on the mine lease is a key part of water management at the mine. Consequently, the soil in these Land Application Areas (LAAs) presents a range of uranium (U) and other metals concentrations. Knowledge of seasonal and temporal changes in soil U and physicochemical parameters at RUM LAAs is important to develop suitable management and rehabilitation strategies. Therefore, soil samples were collected from low, medium, high and very high U sites at RUM LAAs for two consecutive years and the effect of time and season on soil physicochemical parameters particularly U and other major solutes applied in irrigation water was measured. Concentrations of some of the solutes applied in the irrigation water such as sulphur (S), iron (Fe) and calcium (Ca) showed significant seasonal and temporal changes. Soil S, Fe and Ca concentration decreased from year 1 to year 2 and from dry to wet seasons during both years. Soil U followed the same pattern except that we recorded an increase in soil U concentrations at most of the RUM LAAs after year 2 wet season compared to year 2 dry season. Thus, these sites did not show a considerable decrease in soil U concentration from year 1 to year 2. Sites which contained elevated U after wet season 2 also had higher moisture content which suggests that pooling of U containing rainwater at these sites may be responsible for elevated U. Thus, U may be redistributed within RUM LAAs due to surface water movement. The study also suggested that a decrease in U concentrations in LAA soils at very high U (>900 mg kg(-1)) sites is most likely due to transport of particulate matter bound U by surface runoff and U may not be lost from the surface soil due to vertical movement through the soil profile. Uranium attached to particulate matter may reduce its potential for environmental impact. These findings suggest that U is effectively adsorbed by the soils and thus land application may serve as a useful tool for U management in the wet-dry tropics of northern Australia. Copyright © 2015 Elsevier Ltd. All rights reserved.

Do Reductions in Dry Season Transpiration Allow Shallow Soil Water Uptake to Persist in a Tropical Lower Montane Cloud Forest?

NASA Astrophysics Data System (ADS)

Munoz Villers, L. E.; Holwerda, F.; Alvarado-Barrientos, M. S.; Goldsmith, G. R.; Geissert Kientz, D. R.; González Martínez, T. M.; Dawson, T. E.

2016-12-01

Tropical montane cloud forests (TMCF) are ecosystems particularly sensitive to climate change; however, the effects of warmer and drier conditions on TMCF water cycling remain poorly understood. To investigate the plant functional response to reduced water availability, we conducted a study during the mid to late dry season (2014) in the lower limit (1,325 m asl) of the TMCF belt (1200-2500 m asl) in central Veracruz, Mexico. The temporal variation of transpiration rates of dominant upper canopy and mid-story tree species, depth of water uptake, as well as tree water sources were examined using micrometeorological, sapflow and soil moisture measurements, in combination with data on stable isotope (δ18O and δ2H) composition of rain, tree xylem, soil (bulk and low suction-lysimeter) and stream water. The sapflow data suggest that crown conductances decreased as temperature and vapor pressure deficit increased, and soil moisture decreased from the mid to late dry season. Across all samplings (January 21, April 12 and 26), upper canopy species (Quercus spp.) showed more depleted (negative) isotope values compared to mid-story trees (Carpinus tropicalis). Overall, we found that the evaporated soil water pool was the main source for the trees. Furthermore, our MixSIAR Bayesian mixing model results showed that the depth of tree water uptake changed over the course of the dry season. Unexpectedly, a shift in water uptake from deeper (60-120 cm depth) to shallower soil water (0-30 cm) sources was observed, coinciding with the decreases in transpiration rates towards the end of the dry season. A larger reduction in deep soil water contributions was observed for upper canopy trees (from 70±14 to 22±15%) than for mid-story species (from 10±13 to 7±10%). The use of shallow soil water by trees during the dry season seems consistent with the greater root biomass and higher macronutrient concentrations found in the first 10 cm of the soil profiles. These findings are an important step towards enhancing our understanding about the water movement through this TMCF ecosystem, providing information that may be used for forest protection and management under the increasing climate change pressures.

Research on the Effects of Drying Temperature on Nitrogen Detection of Different Soil Types by Near Infrared Sensors.

PubMed

Nie, Pengcheng; Dong, Tao; He, Yong; Xiao, Shupei

2018-01-29

Soil is a complicated system whose components and mechanisms are complex and difficult to be fully excavated and comprehended. Nitrogen is the key parameter supporting plant growth and development, and is the material basis of plant growth as well. An accurate grasp of soil nitrogen information is the premise of scientific fertilization in precision agriculture, where near infrared sensors are widely used for rapid detection of nutrients in soil. However, soil texture, soil moisture content and drying temperature all affect soil nitrogen detection using near infrared sensors. In order to investigate the effects of drying temperature on the nitrogen detection in black soil, loess and calcium soil, three kinds of soils were detected by near infrared sensors after 25 °C placement (ambient temperature), 50 °C drying (medium temperature), 80 °C drying (medium-high temperature) and 95 °C drying (high temperature). The successive projections algorithm based on multiple linear regression (SPA-MLR), partial least squares (PLS) and competitive adaptive reweighted squares (CARS) were used to model and analyze the spectral information of different soil types. The predictive abilities were assessed using the prediction correlation coefficients (R P ), the root mean squared error of prediction (RMSEP), and the residual predictive deviation (RPD). The results showed that the loess (R P = 0.9721, RMSEP = 0.067 g/kg, RPD = 4.34) and calcium soil (R P = 0.9588, RMSEP = 0.094 g/kg, RPD = 3.89) obtained the best prediction accuracy after 95 °C drying. The detection results of black soil (R P = 0.9486, RMSEP = 0.22 g/kg, RPD = 2.82) after 80 °C drying were the optimum. In conclusion, drying temperature does have an obvious influence on the detection of soil nitrogen by near infrared sensors, and the suitable drying temperature for different soil types was of great significance in enhancing the detection accuracy.

Glyphosate and aminomethylphosphonic acid chronic risk assessment for soil biota.

PubMed

von Mérey, Georg; Manson, Philip S; Mehrsheikh, Akbar; Sutton, Peter; Levine, Steven L

2016-11-01

Glyphosate is a broad-spectrum herbicide used widely in agriculture, horticulture, private gardens, and public infrastructure, where it is applied to areas such as roadsides, railway tracks, and parks to control the growth of weeds. The exposure risk from glyphosate and the primary soil metabolite aminomethylphosphonic acid (AMPA) on representative species of earthworms, springtails, and predatory soil mites and the effects on nitrogen-transformation processes by soil microorganisms were assessed under laboratory conditions based on internationally recognized guidelines. For earthworms, the reproductive no-observed-effect concentration (NOEC) was 472.8 mg glyphosate acid equivalent (a.e.)/kg dry soil, which was the highest concentration tested, and 198.1 mg/kg dry soil for AMPA. For predatory mites, the reproductive NOEC was 472.8 mg a.e./kg dry soil for glyphosate and 320 mg/kg dry soil for AMPA, the highest concentrations tested. For springtails, the reproductive NOEC was 472.8 mg a.e./kg dry soil for glyphosate and 315 mg/kg dry soil for AMPA, the highest concentrations tested. Soil nitrogen-transformation processes were unaffected by glyphosate and AMPA at 33.1 mg a.e./kg soil and 160 mg/kg soil, respectively. Comparison of these endpoints with worst-case soil concentrations expected for glyphosate (6.62 mg a.e./kg dry soil) and AMPA (6.18 mg/kg dry soil) for annual applications at the highest annual rate of 4.32 kg a.e./ha indicate very low likelihood of adverse effects on soil biota. Environ Toxicol Chem 2016;35:2742-2752. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

An Arduino Based Citizen Science Soil Moisture Sensor in Support of SMAP and GLOBE

NASA Astrophysics Data System (ADS)

Podest, E.; Das, N. N.; Rajasekaran, E.; Jeyaram, R.; Lohrli, C.; Hovhannesian, H.; Fairbanks, G.

2017-12-01

Citizen science allows individuals anywhere in the world to engage in science by collecting environmental variables. One of the longest running platforms for the collection of in situ variables is the GLOBE program, which is international in scope and encourages students and citizen scientists alike to collect in situ measurements. NASA's Soil Moisture Active Passive (SMAP) satellite mission, which has been acquiring global soil moisture measurements every 3 days of the top 5 cm of the soil since 2015, has partnered with the GLOBE program to engage students from around the world to collect in situ soil moisture and help validate SMAP measurements. The current GLOBE SMAP soil moisture protocol consists in collecting a soil sample, weighing, drying and weighing it again in order to determine the amount of water in the soil. Preparation and soil sample collection can take up to 20 minutes and drying can take up to 3 days. We have hence developed a soil moisture measurement device based on Arduino- microcontrollers along with off-the-shelf and homemade sensors that are accurate, robust, inexpensive and quick and easy to use so that they can be implemented by the GLOBE community and citizen scientists alike. In addition, we have developed a phone app, which interfaces with the Arduino, displays the soil moisture value and send the measurement to the GLOBE database. This talk will discuss building, calibration and validation of the soil moisture measuring device and assessing the quality of the measurements collected. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Soil aggregation and slope stability related to soil density, root length, and mycorrhiza

NASA Astrophysics Data System (ADS)

Graf, Frank; Frei, Martin

2013-04-01

Eco-engineering measures combine the use of living plants and inert mechanical constructions to protect slopes against erosion and shallow mass movement. Whereas in geotechnical engineering several performance standards and guidelines for structural safety and serviceability of construction exist, there is a lack of comparable tools in the field of ecological restoration. Various indicators have been proposed, including the fractal dimension of soil particle size distribution, microbiological parameters, and soil aggregate stability. We present results of an soil aggregate stability investigation and compare them with literature data of the angle of internal friction ?' which is conventionally used in slope stability analysis and soil failure calculation. Aggregate stability tests were performed with samples of differently treated moraine, including soil at low (~15.5 kN/m³) and high (~19.0 kN/m³) dry unit weight, soil planted with Alnus incana (White Alder) as well as the combination of soil planted with alder and inoculated with the mycorrhizal fungus Melanogaster variegatus s.l. After a 20 weeks growth period in a greenhouse, a total of 100 samples was tested and evaluated. Positive correlations were found between the soil aggregate stability and the three variables dry unit weight, root length per soil volume, and degree of mycorrhization. Based on robust statistics it turned out that dry unit weight and mycorrhization degree were strongest correlated with soil aggregate stability. Compared to the non-inoculated control plants, mycorrhized White Alder produced significantly more roots and higher soil aggregate stability. Furthermore, the combined biological effect of plant roots and mycorrhizal mycelia on aggregate stability on soil with low density (~15.5 kN/m³) was comparable to the compaction effect of the pure soil from 15.5 to ~19.0 kN/m³. Literature data on the effect of vegetation on the angle of internal friction ?' of the same moraine showed similar correlations, i.e. that ?' of low density soil material (~15.5 kN/m³) increased by the same amount whether by planting with White Alder or by compaction to ~19.0 kN/m³. Based on this coincidence the method to quantify soil aggregate produced satisfying results which indicate that soil aggregate stability is a potential proxy for ?' and the joint impact of mycorrhizal fungi and plant roots increase the resistance against superficial soil failure. It is concluded that soil aggregate stability mirrors biological effects on soil stability reasonably well and may be used as an indicator to quantify the effectiveness of ecological restoration and stabilisation measures.

Leaf Cutter Ant (Atta cephalotes) Soil Modification and In Situ CO2 Gas Dynamics in a Neotropical Wet Forest

NASA Astrophysics Data System (ADS)

Fernandez Bou, A. S.; Carrasquillo Quintana, O.; Dierick, D.; Harmon, T. C.; Johnson, S.; Schwendenmann, L.; Zelikova, T. J.

2016-12-01

The goal of this work is to advance our understanding of soil carbon cycling in highly productive neotropical wet forests. More specifically, we are investigating the influence of leaf cutter ants (LCA) on soil CO2 gas dynamics in primary and secondary forest soils at La Selva Biological Station, Costa Rica. LCA are the dominant herbivore in tropical Americas, responsible for as much as 50% of the total herbivory. Their presence is increasing and their range is expanding because of forest fragmentation and other human impacts. We installed gas sampling wells in LCA (Atta cephalotes) nest and control sites (non-nests in the same soil and forest settings). The experimental design encompassed land cover (primary and secondary forest) and soil type (residual and alluvial). We collected gas samples monthly over an 18-month period. Several of the LCA nests were abandoned during this period. Nevertheless, we continued to sample these sites for LCA legacy effects. In several of the sites, we also installed sensors to continuously monitor soil moisture content, temperature, and CO2 levels. Within the 18-month period we conducted a 2-month field campaign to collect soil and nest vent CO2 efflux data from 3 of the nest-control pairs. Integrating the various data sets, we observed that for most of the sites nest and control soils behaved similarly during the tropical dry season. However, during the wet season gas well CO2 concentrations increased in the control sites while levels in the nests remained at dry season levels. This outcome suggests that ants modify soil gas transport properties (e.g., tortuosity). In situ time series and efflux sampling campaign data corroborated these findings. Abandoned nest CO2 levels were similar to those of the active nests, supporting the notion of a legacy effect from LCA manipulations. For this work, the period of abandonment was relatively short (several months to 1 year maximum), which appears to be insufficient for estimating the duration effect. Overall, these results demonstrate that LCA exert a significant effect on carbon cycling in rain forest soils.

Biological properties of disturbed and undisturbed Cerrado sensu stricto from Northeast Brazil.

PubMed

Araújo, A S F; Magalhaes, L B; Santos, V M; Nunes, L A P L; Dias, C T S

2017-03-01

The aim of this study was to measure soil microbial biomass and soil surface fauna in undisturbed and disturbed Cerrado sensu stricto (Css) from Sete Cidades National Park, Northeast Brazil. The following sites were sampled under Cerrado sensu stricto (Css) at the park: undisturbed and disturbed Css (slash-and-burn agricultural practices). Total organic and microbial biomass C were higher in undisturbed than in disturbed sites in both seasons. However, microbial biomass C was higher in the wet than in the dry season. Soil respiration did not vary among sites but was higher in the wet than in the dry season. The densities of Araneae, Coleoptera, and Orthoptera were higher in the undisturbed site, whereas the densities of Formicidae were higher in the disturbed site. Non-metric multidimensional scaling analysis separated undisturbed from disturbed sites according to soil biological properties. Disturbance by agricultural practices, such as slash-and-burn, probably resulted in the deterioration of the biological properties of soil under native Cerrado sensu stricto in the Sete Cidades National Park.

Effects of digestion, chemical separation, and deposition on Po-210 quantitative analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seiner, Brienne N.; Morley, Shannon M.; Beacham, Tere A.

Polonium-210 is a radioactive isotope often used to study sedimentation processes, food chains, aerosol behavior, and atmospheric circulations related to environmental sciences. Materials for the analysis of Po-210 range from tobacco leaves or cotton fibers, to soils and sediments. The purpose of this work was to determine polonium losses from a variety of sample types (soil, cotton fiber, and air filter) due to digestion technique, chemical separation, and deposition method for alpha energy analysis. Results demonstrated that yields from a perchloric acid wet-ash were similar to that from a microwave digestion. Both were greater than the dry-ash procedure. The poloniummore » yield from the perchloric acid wet ash was 87 ± 5%, the microwave digestion had a yield of 100 ± 7%, and the dry ash had a yield of 38 ± 5%. The chemical separation of polonium by an anion exchange resin was used only on the soil samples due to the complex nature of this sample. The yield of Po-209 tracer after chemical separation and deposition for alpha analysis was 83 ± 7% for the soil samples. Spontaneous deposition yields for the cotton and air filters were 87 ± 4% and 92 ± 6%, respectively. Based on the overall process yields for each sample type the amount of Po-210 was quantified using alpha energy analysis. The soil contained 0.18 ± 0.08 Bq/g, the cotton swipe contained 0.7 mBq/g, and the air filter contained 0.04 ± 0.02 mBq/g. High and robust yields of polonium are possible using a suitable digestion, separation, and deposition method.« less

Application of a Stir Bar Sorptive Extraction sample preparation method with HPLC for soil fungal biomass determination in soils from a detrital manipulation study.

PubMed

Beni, Áron; Lajtha, Kate; Kozma, János; Fekete, István

2017-05-01

Ergosterol is a sterol found ubiquitously in cell membranes of filamentous fungi. Although concentrations in different fungal species span the range of 2.6 to 42μg/mL of dry mass, many studies have shown a strong correlation between soil ergosterol content and fungal biomass. The analysis of ergosterol in soil therefore could be an effective tool for monitoring changes in fungal biomass under different environmental conditions. Stir Bar Sorptive Extraction (SBSE) is a new sample preparation method to extract and concentrate organic analytes from liquid samples. SBSE was here demonstrated to be a simple, fast, and cost effective method for the quantitative analysis of ergosterol from field-collected soils. Using this method we observed that soil ergosterol as a measure of fungal biomass proved to be a sensitive indicator of soil microbial dynamics that were altered by changes in plant detrital inputs to soils in a long-term field experiment. Copyright © 2017 Elsevier B.V. All rights reserved.

A High-Performance Liquid Chromatography-Based Screening Method for the Analysis of Atrazine, Alachlor, and Ten of Their Transformation Products

USGS Publications Warehouse

Schroyer, B.R.; Capel, P.D.

1996-01-01

A high-performance liquid Chromatography (HPLC) method is presented for the for the fast, quantitative analysis of the target analytes in water and in low organic-carbon, sandy soils that are known to be contaminated with the parent herbicides. Speed and ease of sample preparation was prioritized above minimizing detection limits. Soil samples were extracted using 80:20 methanol:water (volume:volume). Water samples (50 ??L) were injected directly into the HPLC without prior preparation. Method quantification limits for soil samples (10 g dry weight) and water samples ranged from 20 to 110 ng/g and from 20 to 110 ??g/L for atrazine and its transformation products and from 80 to 320 ng/g and from 80 to 320 ??g/L for alachlor and its transformation products, respectively.

Soil strength and macropore volume limit root elongation rates in many UK agricultural soils.

PubMed

Valentine, Tracy A; Hallett, Paul D; Binnie, Kirsty; Young, Mark W; Squire, Geoffrey R; Hawes, Cathy; Bengough, A Glyn

2012-07-01

Simple indicators of crop and cultivar performance across a range of soil types and management are needed for designing and testing sustainable cropping practices. This paper determined the extent to which soil chemical and physical properties, particularly soil strength and pore-size distribution influences root elongation in a wide range of agricultural top soils, using a seedling-based indicator. Intact soil cores were sampled from the topsoil of 59 agricultural fields in Scotland, representing a wide geographic spread, range of textures and management practices. Water release characteristics, dry bulk density and needle penetrometer resistance were measured on three cores from each field. Soil samples from the same locations were sieved, analysed for chemical characteristics, and packed to dry bulk density of 1.0 g cm(-3) to minimize physical constraints. Root elongation rates were determined for barley seedlings planted in both intact field and packed soil cores at a water content close to field capacity (-20 kPa matric potential). Root elongation in field soil was typically less than half of that in packed soils. Penetrometer resistance was typically between 1 and 3 MPa for field soils, indicating the soils were relatively hard, despite their moderately wet condition (compared with <0.2 MPa for packed soil). Root elongation was strongly linked to differences in physical rather than chemical properties. In field soil root elongation was related most closely to the volume of soil pores between 60 µm and 300 µm equivalent diameter, as estimated from water-release characteristics, accounting for 65.7 % of the variation in the elongation rates. Root elongation rate in the majority of field soils was slower than half of the unimpeded (packed) rate. Such major reductions in root elongation rates will decrease rooting volumes and limit crop growth in soils where nutrients and water are scarce.

Distribution of 137Cs in surface soil of Fraser's Hill, Pahang, Malaysia

NASA Astrophysics Data System (ADS)

Bakar, Ahmad Sanadi Abu; Hamzah, Zaini; Saat, Ahmad

2017-01-01

Caesium-137 (137Cs) in an anthropogenic radionuclide originated from the fission of fissile materials. Nuclear weapons testing during the 1960s and the Chernobyl disaster introduced substantial amount of 137Cs into the atmosphere that are then eventually deposited back to earth's surface. Caesium-137 can be used as tracer to study soil movements since it adsorbs to soil particles. This paper aims to describe the distribution of 137Cs in surface soil of Fraser's Hill, Pahang, determine the levels of 137Cs here compared to other areas, and to check correlation of 137Cs levels to physical data. A series of sampling were carried out between February 2014 and August 2015. Soil samples were taken from 31 locations using soil scraper. The samples were then taken to the laboratory to be dried, homogenized, grinded and sieved. The activity concentration of 137Cs in the samples was determined using gamma spectroscopy. The activity concentration was found to be between 0.26 Bq/kg and 5.14 Bq/kg. Although this paper only studies surface soil, 137Cs is expected to be present within the soil body. Further study of 137Cs in the soil body can be used to predictive model for soil erosion.

Communities of terrestrial nematodes after different approaches to heathland restoration

NASA Astrophysics Data System (ADS)

Radochova, Petra; Frouz, Jan

2016-04-01

Since the 20th century, the distribution of European heathlands rapidly decreased due to agricultural intensification, heavy use of artificial fertilizers or acidification (Aerts & Heil, 1993). Therefore, various attempts of heathland restoration are under way in these days. Analysis of nematode community composition can be one of the tools suitable for succession evaluation (Ferris et al., 2001). In 2011, 2013 and 2014, soil samples were collected from heathland restoration experiment (launched in 2011) where different restoration methods were applied in a 3 × 3 factorial experiment; existing heathlands were also sampled to identify the target community both in dry and wet heathland. A total of 60 samples of extracted nematodes were analysed for absolute abundance, trophic groups, and genera dominance. Various indices were calculated to describe the nematode community. We were able to prove faster development of wet heathlands towards the target community. However, because of large data variability, there was no significant difference between treatments. Development of wet and dry heathlands differed also in increased proportion of omniphagous nematodes in 2013 and predators in 2014 in dry heathlands. After three years of heathland restoration, nematode community has not yet reached parameters of the target community. References Aerts, R., Heil, G. W., 1993. Heathlands: patterns and processes in a changing environment, 1st ed, Geobotany: 20. Springer Netherlands, Dordrecht, p. 229. Ferris, H., Bongers, T., De Goede, R. G. M., 2001. A framework for soil food web diagnostics: Extension of the nematode faunal analysis oncept. Appl. Soil Ecol. 18, 13-29.

The relation between forest structure and soil burn severity

Treesearch

Theresa B. Jain; Russell T. Graham; David S. Pilliod

2006-01-01

A study funded through National Fire Plan evaluates the relation between pre-wildfire forest structure and post-wildfire soil burn severity across three forest types: dry, moist, and cold forests. Over 73 wildfires were sampled in Idaho, Oregon, Montana, Colorado, and Utah, which burned between 2000 and 2003. Because of the study’s breadth, the results are applicable...

Estimation of Compaction Parameters Based on Soil Classification

NASA Astrophysics Data System (ADS)

Lubis, A. S.; Muis, Z. A.; Hastuty, I. P.; Siregar, I. M.

2018-02-01

Factors that must be considered in compaction of the soil works were the type of soil material, field control, maintenance and availability of funds. Those problems then raised the idea of how to estimate the density of the soil with a proper implementation system, fast, and economical. This study aims to estimate the compaction parameter i.e. the maximum dry unit weight (γ dmax) and optimum water content (Wopt) based on soil classification. Each of 30 samples were being tested for its properties index and compaction test. All of the data’s from the laboratory test results, were used to estimate the compaction parameter values by using linear regression and Goswami Model. From the research result, the soil types were A4, A-6, and A-7 according to AASHTO and SC, SC-SM, and CL based on USCS. By linear regression, the equation for estimation of the maximum dry unit weight (γdmax *)=1,862-0,005*FINES- 0,003*LL and estimation of the optimum water content (wopt *)=- 0,607+0,362*FINES+0,161*LL. By Goswami Model (with equation Y=mLogG+k), for estimation of the maximum dry unit weight (γdmax *) with m=-0,376 and k=2,482, for estimation of the optimum water content (wopt *) with m=21,265 and k=-32,421. For both of these equations a 95% confidence interval was obtained.

Arbuscular Mycorrhiza Alleviates Restrictions to Substrate Water Flow and Delays Transpiration Limitation to Stronger Drought in Tomato.

PubMed

Bitterlich, Michael; Sandmann, Martin; Graefe, Jan

2018-01-01

Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic conductivity were rarely quantified. Hence, we asked whether inoculation with AMF affects substrate water retention, water transport properties and at which drought intensity those factors become limiting for plant transpiration. Solanum lycopersicum plants were set up in the glasshouse, inoculated or not with Funneliformis mosseae , and grown for 35 days under ample water supply. After mycorrhizal establishment, we harvested three sets of plants, one before (36 days after inoculation) and the second (day 42) and third (day 47) within a sequential drying episode. Sampling cores were introduced into pots before planting. After harvest, moisture retention and substrate conductivity properties were assessed and water retention and hydraulic conductivity models were fitted. A root water uptake model was adopted in order to identify the critical substrate moisture that induces soil derived transpiration limitation. Neither substrate porosity nor saturated water contents were affected by inoculation, but both declined after substrates dried. Drying also caused a decline in pot water capacity and hydraulic conductivity. Plant available water contents under wet (pF 1.8-4.2) and dry (pF 2.5-4.2) conditions increased in mycorrhizal substrates and were conserved after drying. Substrate hydraulic conductivity was higher in mycorrhizal pots before and during drought exposure. After withholding water from pots, higher substrate drying rates and lower substrate water potentials were found in mycorrhizal substrates. Mycorrhiza neither affected leaf area nor root weight or length. Consistently with higher substrate drying rates, AMF restored the plant hydraulic status, and increased plant transpiration when soil moisture declined. The water potential at the root surface and the resistance to water flow in the rhizosphere were restored in mycorrhizal pots although the bulk substrate dried more. Finally, substrates colonized by AMF can be more desiccated before substrate water flux quantitatively limits transpiration. This is most pronounced under high transpiration demands and complies with a difference of over 1,000 hPa in substrate water potential.

Development and survival of Anopheles gambiae eggs in drying soil: influence of the rate of drying, egg age, and soil type.

PubMed

Shililu, J I; Grueber, W B; Mbogo, C M; Githure, J I; Riddiford, L M; Beier, J C

2004-09-01

Little is known about the contribution made by the egg stage of African malaria vectors to the rapid rise in adult populations following the onset of seasonal rains. To examine this issue, we evaluated the viability of Anopheles gambiae eggs in drying soil in the laboratory. Survival data were collected from field-caught mosquitoes kept in sandy loam soil and laboratory-reared colonies kept in sandy loam soil and black cotton soil. Under high, medium, and low soil-moisture regimes, egg viability declined sharply with increased duration of drying. Eggs remained viable in drying sandy loam soil for 1, 5, and 10 days, but not after 15 or 20 days. The most dramatic decline in hatching success occurred between drying days 1 (78-83% hatch) and 5 (20-23% hatch). In contrast, eggs reared in high-moisture black cotton soil remained viable for up to 15 days. Furthermore, after 5 drying days, high-, medium-, and low-moisture soils averaged 59, 47, and 31% hatching success, respectively. We recovered unhatched eggs from sandy loam soils to examine the developmental status of the embryos. A majority of the unhatched eggs that were recovered from days 15 and 20 in sandy loam soils contained fully developed late-stage embryos. Thus, unhatched eggs completed embryonic development but probably died before receiving an appropriate hatching stimulus. Our results suggest that the absolute moisture content of the soil does not alone determine hatching success of anopheline eggs. Rather, soil moisture, together with the rate of drying, physiological factors associated with the age of the egg, and the type of soil in which the egg rests likely influence survival.

A study on zinc distribution in calcareous soils for cowpea (Vigna Unguiculata L.) and barely ( Hordeum Vulgare L.)

NASA Astrophysics Data System (ADS)

Boroomand, Naser; Maleki, Mohammad Reza

2010-05-01

Compared to other cereals, such as wheat and barley cultivars which have low sensitivity to Zn deficiency, cowpea is sensitive to zinc (Zn) deficiency, however it extensively grows even in soils with deficient in Zn. A 8-week greenhouse experiment was conducted to study the response of cowpea and barely to Zn in calcareous soils with different DTPA- Zn. The soil samples were taken from soil surface up to 0.3 m in which their DTPA- Zn ranged from 0.5 to 3.5 mg kg-1. Shoot dry matter, concentration and uptake of Zn were found to be significantly correlated with soil DTPA- Zn in cowpea and barely. Critical deficiency level of Zn in cowpea was 1.3 mg kg-1 in soil and 28.5 mg kg-1 in shoot dry matter, however, to barely symptoms of Zn deficiency was not observed and concentration of Zn was higher than the critical level reported in literatures. Organic carbon (OC), calcium carbonate equivalent (CCE), pH and field capacity soil moisture content(FC) were significantly correlated with plant responses to Zn which were the most influenced characteristics to Zn uptake by plants.

Rice husk ash (RHA) as a partial cement replacement in modifying peat soil properties

NASA Astrophysics Data System (ADS)

Daud, Nik Norsyahariati Nik; Daud, Mohd Nazrin Mohd; Muhammed, Abubakar Sadiq

2018-02-01

This paper describes the effect of rice husk ash (RHA) and ordinary Portland cement (OPC) as a potential binder for modifying the properties of peat soil. The amounts RHA and OPC added to the peat soil sample, as percentage of the dry soil mass were in the range of 10-15% and 15%, respectively. Observations were made for the changes in the properties of the soil such as maximum dry density (MDD), optimum moisture content (OMC) and shear strength. Scanning Electron Micrograph-Energy Dispersive X-Ray (SEM-EDX) test were also conducted to observe the microstructure of treated and untreated peat soil. The results show that the modified soil of MDD and OMC values are increased due to the increment amount of binder material. Shear strength values of modified peat showing a good result by assuming that it is relative to the formation of major reaction products such as calcium silicate hydrate (C-S-H). The presence of C-S-H formation is indicated by the results produced from microstructural analysis of peat before and after modification process. This depicts the potential usage of RHA as a partial cement replacement in peat soil which is also improving its engineering properties.

Effect of water saturation in soil organic matter on the partition of organic compounds

USGS Publications Warehouse

Rutherford, D.W.; Chlou, G.T.

1992-01-01

The sorption of benzene, trichloroethylene, and carbon tetrachloride at room temperature from water solution and from vapor on two high-organic-content soils (peat and muck) was determined in order to evaluate the effect of water saturation on the solute partition in soil organic matter (SOM). The uptake of water vapor was similarly determined to define the amounts of water in the saturated soil samples. In such high-organic-content soils the organic vapor sorption and the respective solute sorption from water exhibit linear isotherms over a wide range of relative concentrations. This observation, along with the low BET surface areas of the samples, suggests that partition in the SOM of the samples is the dominant process in the uptake of these liquids. A comparison of the sorption from water solution and from vapor phase shows that water saturation reduces the sorption (partition) efficiency of SOM by ?? 42%; the saturated water content is ??38% by weight of dry SOM. This reduction is relatively small when compared with the almost complete suppression by water of organic compound adsorption on soil minerals. While the effect of water saturation on solute uptake by SOM is much expected in terms of solute partition in SOM, the influence of water on the solubility behavior of polar SOM can be explained only qualitatively by regular solution theory. The results suggest that the major effect of water in a drying-wetting cycle on the organic compound uptake by normal low-organic-content soils (and the associated compound's activity) is the suppression of adsorption by minerals rather than the mitigation of the partition effect in SOM.

Cyanobacterial crusts linked to soil productivity under different grazing management practices in Northern Australia

NASA Astrophysics Data System (ADS)

Alchin, Bruce; Williams, Wendy

2015-04-01

In arid and semi-arid Australia, the central role of healthy soil ecosystems in broad-acre grazing lands may be attributed to the widespread presence of cyanobacterial crusts. In terms of soil nutrient cycling and stability their role is particularly crucial in a climate dominated by annual dry seasons and variable wet seasons. In this study, we aimed to measure the contribution of cyanobacteria to soil nutrient cycling under contrasting levels of disturbance associated with grazing management. Field sampling was carried out on six paired sites (twelve properties) located across an east-west 3,000 km transect that covered different rangeland types on grazing properties in northern Australia (Queensland, Northern Territory and Western Australia). At each location paired sites were established and two different management systems were assessed, cell-paddock rotations (25-400 ha) and continuous grazing (200-2,000 ha). Cyanobacterial soil crusts were recorded from all of the twelve sites and cyanobacteria with the capacity to fix nitrogen were found at ten of the twelve sites. The overall diversity of cyanobacteria varied from three to ten species under any type of grazing system. As field work was conducted in the dry season, it is likely that the diversity may be greater in the wet season than the initial data may indicate. The average cyanobacterial soil crust cover across soil surfaces, between grass tussocks, during the dry season was estimated to be 50.9% and, 42.6% in the early wet season. This reflected longer established crust cover (dry season) versus newly established crusts. There was a high level of variability in the biomass of cyanobacteria however; the grazing system did not have any marked effect on the biomass for any one rangeland type. The grazing system differences did not appear to significantly influence the diversity at any location except on a floodplain in the Pilbara (WA). Biological nitrogen fixation by cyanobacteria was recorded at all sites. Nitrogen fixation rates were significantly higher in the wet season samples compared to the dry season. Rates of nitrogen fixation, mineralisable nitrogen and cyanobacterial biomass were comparative to other studies both in Australia and globally. Eleven of the twelve sites had higher plant-available (mineralisable) nitrogen in the 0-1 cm depth compared to the 1-5 cm depth. Nitrogen isotopes showed that the nitrogen concentration found in the surface soils (0-1 cm) from five sites originated from cyanobacterial nitrogen fixation. At the remaining sites the isotopic signatures were slightly more positive, indicative of fractionation. The results have substantiated the link between cyanobacteria and their contribution to carbon and nitrogen cycling across the northern Australian rangelands. The data also highlights the variability between sites and management practices that influence biogeochemical processes that affect soil productivity.

Removal of polycyclic aromatic hydrocarbons from soil using a composite material containing iron and activated carbon in the freeze-dried calcium alginate matrix: Novel soil cleanup technique.

PubMed

Funada, Mako; Nakano, Takeshi; Moriwaki, Hiroshi

2018-06-05

A novel clean-up technology to remove polycyclic aromatic hydrocarbons (PAHs) from solid samples by magnetic separation using a composite containing iron powder as a magnetic material and activated carbon as an adsorbent in the freeze-dried calcium alginate matrix (Fe-AC-alg) has been developed. The Fe-AC-alg powder (50 mg), mixed with 1.0 g of glass beads having 12 kinds of adsorbed PAHs, was shaken without adding solvents at 300 rpm. After shaking, the Fe-AC-alg powder was separated using a permanent magnet. The quantity of the PAHs extracted from the glass beads treated by this method was determined. The removal (%) of the PAHs was over 96%. A roadside soil sample (10 g) was mixed with the Fe-AC-alg (1.0 g) for 2 weeks. The removal (%) of benzo[a]pyrene from the sample by the presented technique was 78%. The toxic equivalent concentration (Σ BaP eq ) for the sample decreased from 0.27 to 0.10 mg kg -1 by this method. The presented method is very simple, economical, and environment-friendly. Copyright © 2018 Elsevier B.V. All rights reserved.

SMAP soil moisture drying more rapid than observed in situ following rainfall events

USDA-ARS?s Scientific Manuscript database

We examine soil drying rates by comparing observations from the NASA Soil Moisture Active Passive (SMAP) mission to surface soil moisture from in situ probes during drydown periods at SMAP validation sites. SMAP and in situ probes record different soil drying dynamics after rainfall. We modeled this...

Impact of effluents from a car battery manufacturing plant in Nigeria on water, soil, and food qualities.

PubMed

Orisakwe, Orish Ebere; Asomugha, Rose; Afonne, Onyenmechi Johnson; Anisi, C N; Obi, Ejeatuluchukwualo; Dioka, Chudi Emma

2004-01-01

The authors investigated the impact of effluents from a car battery manufacturing plant in Nnewi, Nigeria, on water, soil, and food qualities. The authors analyzed heavy metals mercury, arsenic, lead, cadmium and nickel in tap and cassava waters, soil, dried cassava tuber, and edible fruit samples from the company, using an atomic absorption spectrophotometer. Other parameters the authors analyzed include pH, electrical conductivity (EC), salinity (SAL), total hardness (TH), biological oxygen demand (BOD), volatile and non-volatile solids, and bacterial and fungal loads of the soil samples. Results show that lead had the highest concentration in all the samples, with the soil samples having the highest lead concentration (38-12 ppm, 102 ppm) and the water samples having the lowest (0.02-0.20 ppm). Mercury had the lowest concentration (<0.0002 ppm) in all the samples. Soil sample B had the highest concentration of all the metals tested. Cassava water had higher levels of EC, SAL, TH, BOD, and volatile and nonvolatile solids, but lower pH than tap water. Bacterial loads were higher than fungal loads in all the soil samples. Because there was moderate contamination of the environment by some of the metals studied, with lead being exceptionally high and above the specified international standards, the authors recommend control measures to reduce lead exposure to the local populace within and around this industry.

Nitrogen supply modulates the effect of changes in drying-rewetting frequency on soil C and N cycling and greenhouse gas exchange.

PubMed

Morillas, Lourdes; Durán, Jorge; Rodríguez, Alexandra; Roales, Javier; Gallardo, Antonio; Lovett, Gary M; Groffman, Peter M

2015-10-01

Climate change and atmospheric nitrogen (N) deposition are two of the most important global change drivers. However, the interactions of these drivers have not been well studied. We aimed to assess how the combined effect of soil N additions and more frequent soil drying-rewetting events affects carbon (C) and N cycling, soil:atmosphere greenhouse gas (GHG) exchange, and functional microbial diversity. We manipulated the frequency of soil drying-rewetting events in soils from ambient and N-treated plots in a temperate forest and calculated the Orwin & Wardle Resistance index to compare the response of the different treatments. Increases in drying-rewetting cycles led to reductions in soil NO3- levels, potential net nitrification rate, and soil : atmosphere GHG exchange, and increases in NH4+ and total soil inorganic N levels. N-treated soils were more resistant to changes in the frequency of drying-rewetting cycles, and this resistance was stronger for C- than for N-related variables. Both the long-term N addition and the drying-rewetting treatment altered the functionality of the soil microbial population and its functional diversity. Our results suggest that increasing the frequency of drying-rewetting cycles can affect the ability of soil to cycle C and N and soil : atmosphere GHG exchange and that the response to this increase is modulated by soil N enrichment. © 2015 John Wiley & Sons Ltd.

[Temporal-spatial difference of ecotoxicity and heavy metals pollution in Shima catchment, Dongguan].

PubMed

Gao, Lei; Chen, Jian-Yao; Ke, Zhi-Ting; Wang, Jiang; Yang, Xue-Yun; Shimizu, Yuta

2013-08-01

Shima River, a tributary of Dongjiang River, located in Dongguan City of Guangdong Province, has been seriously polluted in the last 30 years. Water samples were collected from the river and the aquifer and the soil samples were collected as well in the wet (June) and dry (February) season to investigate the temporal and spatial variations of water quality in terms of heavy metal concentrations and inhibition rate of the luminescent bacterium (Vibrio fischeri, LUMIStox 300). Heavy metal concentrations and inhibition rate in river water were found decreasing from the upstream to the downstream, with metal concentrations exceeding the national surface water quality standard (Class I) for all samples and a highest inhibition of 38.34% (equivalent to moderate toxic) at R1 in the dry season. Significant difference (P < 0.01 or P < 0.001) in the wet and dry season was identified in both metal concentrations and inhibition rate, except at R11, which showed a inhibition rate of 15.56%, higher than those in all other samples in the wet season. Inhibition rate at GW4, GW5 and GW6 showed significant difference (P < 0.01 or P < 0.001) in the two periods, and the highest inhibition rate (15.88%) at GW6 in the dry season was considered as low in toxicity. The positive correlations (P < 0.05 or P < 0.01) between heavy metals (Zn, Fe, Mn and Ni) and inhibition rate were identified with correlation coefficients of 0.452, 0.567, 0.726 and 0.475, respectively. Heavy metal pollution of soil (Cu, Ni and Zn) near the river was due to the interaction between the river and the groundwater. Cd was heavily accumulated in the soil, while elevated concentrations of Fe and Mn were found in the river and the groundwater was heavily polluted by Ni.

Assessment of subsurface chlorinated solvent contamination using tree cores at the front street site and a former dry cleaning facility at the Riverfront Superfund site, New Haven, Missouri, 1999-2003

USGS Publications Warehouse

Schumacher, John G.; Struckhoff, Garrett C.; Burken, Joel G.

2004-01-01

Tree-core sampling has been a reliable and inexpensive tool to quickly assess the presence of shallow (less than about 30 feet deep) tetrachloroethene (PCE) and trichloroethene (TCE) contamination in soils and ground water at the Riverfront Superfund Site. This report presents the results of tree-core sampling that was successfully used to determine the presence and extent of chlorinated solvent contamination at two sites, the Front Street site (operable unit OU1) and the former dry cleaning facility, that are part of the overall Riverfront Superfund Site. Traditional soil and ground-water sampling at these two sites later confirmed the results from the tree-core sampling. Results obtained from the tree-core sampling were used to design and focus subsequent soil and ground-water investigations, resulting in substantial savings in time and site assessment costs. The Front Street site is a small (less than 1-acre) site located on the Missouri River alluvium in downtown New Haven, Missouri, about 500 feet from the south bank of the Missouri River. Tree-core sampling detected the presence of subsurface PCE contamination at the Front Street site and beneath residential property downgradient from the site. Core samples from trees at the site contained PCE concentrations as large as 3,850 mg-h/kg (micrograms in headspace per kilogram of wet core) and TCE concentrations as large as 249 mg-h/kg. Soils at the Front Street site contained PCE concentrations as large as 6,200,000 mg/kg (micrograms per kilogram) and ground-water samples contained PCE concentrations as large as 11,000 mg/L (micrograms per liter). The former dry cleaning facility is located at the base of the upland that forms the south bank of the Missouri River alluvial valley. Tree-core sampling did not indicate the presence of PCE or TCE contamination at the former dry cleaning facility, a finding that was later confirmed by the analyses of soil samples collected from the site. The lateral extent of PCE contamination in trees was in close agreement with the extent of subsurface PCE contamination determined using traditional soil and ground-water sampling methods. Trees growing in soils containing PCE concentrations of 60 to 5,700 mg/kg or larger or overlying ground water containing PCE concentrations from 5 to 11,000 mg/L generally contained detectable concentrations of PCE. The depth to contaminated ground water was about 20 to 25 feet below the land surface. Significant quantitative relations [probability (p) values of less than 0.05 and correlation coefficient (r2) values of 0.88 to 0.90] were found between PCE concentrations in trees and subsurface soils between 4 and 16 feet deep. The relation between PCE concentrations in trees and underlying ground water was less apparent (r2 value of 0.17) and the poor relation is thought to be the result of equilibrium with PCE concentrations in soil and vapor in the unsaturated zone. Based on PCE concentrations detected in trees at the Front Street site and trees growing along contaminated tributaries in other operable units, and from field hydroponic experiments using hybrid poplar cuttings, analysis of tree-core samples appears to be able to detect subsurface PCE contamination in soils at levels of several hundred micrograms per liter or less and PCE concentrations in the range of 8 to 30 mg/L in ground water in direct contact with the roots. Loss of PCE from tree trunks by diffusion resulted in an exponential decrease in PCE concentrations with increasing height above the land surface in most trees. The rate of loss also appeared to be a function of the size and growth characteristics of the tree as some trees exhibited a linear loss with increasing height. Diffusional loss of PCE in small (0.5-inch diameter) trees was observed to occur at a rate more than 10 times larger than in trees 6.5 inches in diameter. Concentrations of PCE also exhibited directional variability around the tree trunks and concentration differe

Lead distribution and its potential risk to the environment: lesson learned from environmental monitoring of abandon mine.

PubMed

Nobuntou, Wanida; Parkpian, Preeda; Oanh, Nguyen Thi Kim; Noomhorm, Athapol; Delaune, R D; Jugsujinda, Aroon

2010-11-01

There are many abandon and existing mines (tin, lead and zinc) in the mountainous areas of Thailand. Toxic elements including heavy metals such as lead (Pb), cadmium (Cd) and arsenic (As) have been released and transported from the mining sites to the adjacent landscape. In Thong Pha Phum District, Kanchanaburi Province, Thailand Pb contamination in the vicinity of the mine has occurred which could lead to potential health problems in downstream communities. To better understand current status of Pb contamination and accumulation in the surrounding environment and potential health impact, surface sediment, soil and plant samples were collected seasonally from representative monitoring sites along the aquatic track or flow regime. Potential health risk was determined using hazard quotient (HQ) as an index for local inhabitants who consume rice. Environmental monitoring illustrated that Pb concentrations in the surface sediment was as high as 869.4 mg kg(-1) dry weight and varied differently among stations sampled. Lead content in agricultural soil ranged between 137.8 to 613.5 mg kg(-1) dry weight and was inversely proportion to the distance from the point source. Moreover Pb was transported from the point source to down hill areas. At the highly polluted monitoring stations (S1, S2, and S3), concentrations of Pb exceeded the maximum allowable concentration for Pb in agricultural soil (300 mg kg(-1)) by 1.7-2 times. The Pb in soil was primarily associated with Fe/Mn oxides bound fraction (46-56%) followed by the organic bound fraction (25-30%). Lead uptake by plant varied and was species dependent. However root and tuber crops like cassava (19.92 mg Pb kg(-1) dry weight) and curcumin (3.25 mg Pb kg(-1) dry weight) could have removed Pb from the soil which suggest growing root crops in Pb contaminated soils should be avoided. However Cd, a co-contaminant at one of monitored stations (S4) yielded rice grain with Cd exceeding the maximum allowable concentration suggesting some potential health risk (HQ = 5.34) if people consume rice grown at this station. Overall result shows a low risk associated with Pb release into the environment.

Distribution and Diversity of Soil Microfauna from East Antarctica: Assessing the Link between Biotic and Abiotic Factors

PubMed Central

Velasco-Castrillón, Alejandro; Schultz, Mark B.; Colombo, Federica; Gibson, John A. E.; Davies, Kerrie A.; Austin, Andrew D.; Stevens, Mark I.

2014-01-01

Terrestrial life in Antarctica has been described as some of the simplest on the planet, and mainly confined to soil microfaunal communities. Studies have suggested that the lack of diversity is due to extreme environmental conditions and thought to be driven by abiotic factors. In this study we investigated soil microfauna composition, abundance, and distribution in East Antarctica, and assessed correlations with soil geochemistry and environmental variables. We examined 109 soil samples from a wide range of ice-free habitats, spanning 2000 km from Framnes Mountains to Bailey Peninsula. Microfauna across all samples were patchily distributed, from complete absence of invertebrates to over 1600 specimens/gram of dry weight of soil (gdw), with highest microfauna abundance observed in samples with visible vegetation. Bdelloid rotifers were on average the most widespread found in 87% of sampled sites and the most abundant (44 specimens/gdw). Tardigrades occurred in 57% of the sampled sites with an abundance of 12 specimens/gdw. Nematodes occurred in 71% of samples with a total abundance of 3 specimens/gdw. Ciliates and mites were rarely found in soil samples, with an average abundance of 1.3 and 0.04 specimens/gdw, respectively. We found that microfaunal composition and abundance were mostly correlated with the soil geochemical parameters; phosphorus, NO3 − and salinity, and likely to be the result of soil properties and historic landscape formation and alteration, rather than the geographic region they were sampled from. Studies focusing on Antarctic biodiversity must take into account soil geochemical and environmental factors that influence population and species heterogeneity. PMID:24498126

The Impact of Diesel Oil Pollution on the Hydrophobicity and CO2 Efflux of Forest Soils.

PubMed

Hewelke, Edyta; Szatyłowicz, Jan; Hewelke, Piotr; Gnatowski, Tomasz; Aghalarov, Rufat

2018-01-01

The contamination of soil with petroleum products is a major environmental problem. Petroleum products are common soil contaminants as a result of human activities, and they are causing substantial changes in the biological (particularly microbiological) processes, chemical composition, structure and physical properties of soil. The main objective of this study was to assess the impact of soil moisture on CO 2 efflux from diesel-contaminated albic podzol soils. Two contamination treatments (3000 and 9000 mg of diesel oil per kg of soil) were prepared for four horizons from two forest study sites with different initial levels of soil water repellency. CO 2 emissions were measured using a portable infrared gas analyser (LCpro+, ADC BioScientific, UK) while the soil samples were drying under laboratory conditions (from saturation to air-dry). The assessment of soil water repellency was performed using the water drop penetration time test. An analysis of variance (ANVOA) was conducted for the CO 2 efflux data. The obtained results show that CO 2 efflux from diesel-contaminated soils is higher than efflux from uncontaminated soils. The initially water-repellent soils were found to have a bigger CO 2 efflux. The non-linear relationship between soil moisture content and CO 2 efflux only existed for the upper soil horizons, while for deeper soil horizons, the efflux is practically independent of soil moisture content. The contamination of soil by diesel leads to increased soil water repellency.

Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil.

PubMed

Gattai, Graziella S; Pereira, Sônia V; Costa, Cynthia M C; Lima, Cláudia E P; Maia, Leonor C

2011-07-01

The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg(-1)) to uncontaminated soil (37 mg Pb Kg soil(-1)) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil.

Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil

PubMed Central

Gattai, Graziella S.; Pereira, Sônia V.; Costa, Cynthia M. C.; Lima, Cláudia E. P.; Maia, Leonor C.

2011-01-01

The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg-1) to uncontaminated soil (37 mg Pb Kg soil-1) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil. PMID:24031701

Responses of seminal wheat seedling roots to soil water deficits.

PubMed

Trejo, Carlos; Else, Mark A; Atkinson, Christopher J

2018-04-01

The aims of this paper are to develop our understanding of the ways by which soil water deficits influence early wheat root growth responses, particularly how seminal roots respond to soil drying and the extent to which information on differences in soil water content are conveyed to the shoot and their impact on shoot behaviour. To achieve this, wheat seedlings have been grown, individually for around 25 days after germination in segmented soil columns within vertical plastic compartments. Roots were exposed to different soil volumetric moisture contents (SVMC) within the two compartments. Experiments where the soil in the lower compartment was allowed to dry to different extents, while the upper was maintained close to field capacity, showed that wheat seedlings allocated proportionally more root dry matter to the lower drier soil compartment. The total production of root, irrespective of the upper or lower SVMC, was similar and there were no detected effects on leaf growth rate or gas exchange. The response of seminal roots to proportionally increase their allocation of dry matter, to the drier soil was unexpected with such plasticity of roots system development traditionally linked to heterogeneous nutrient distribution than accessing soil water. In experiments where the upper soil compartment was allowed to dry, root growth slowed and leaf growth and gas exchange declined. Subsequent experiments used root growth rates to determine when seminal root tips first came into contact with drying soil, with the intentions of determining how the observed root growth rates were maintained as an explanation for the observed changes in root allocation. Measurements of seminal root ABA and ethylene from roots within the drying soil are interpreted with respect to what is known about the physiological control of root growth in drying soil. Copyright © 2018 Elsevier GmbH. All rights reserved.

Compost and sulfur affect the mobilization and phyto-availability of Cd and Ni to sorghum and barnyard grass in a spiked fluvial soil.

PubMed

Shaheen, Sabry M; Balbaa, Ali A; Khatab, Alaa M; Rinklebe, Jörg

2017-12-01

Soil reclamation via additives can cause contradictory effects on the mobilization of toxic elements in soils under dry and wet conditions. Therefore, our aim was to investigate the impact of compost and sulfur in two rates (1.25 and 2.5%) on fractionation, mobilization, and phyto-availability of cadmium (Cd) and nickel (Ni) to sorghum (dry soil) and barnyard grass (wet soil) in a fluvial soil spiked with 25 mg Cd or 200 mg Ni/kg soil. Compost decreased the solubility and mobilization of Cd (especially in dry soil) and Ni (in both soils). Sulfur increased the solubility of Cd (31% in dry soil-49% in wet soil) and Ni (4.6% in wet soil-8.7% in dry soil). Sulfur altered the carbonate fraction of Cd to the soluble fraction and the residual fraction of Cd and Ni to the non-residual fraction. Compost decreased Cd and increased Ni in sorghum, but enhanced Cd and degraded Ni in grass. Sulfur increased Cd and Ni in both plants, and the increasing rate of Cd was higher in grass than in sorghum, while Ni was higher in sorghum than in grass. These results suggest that compost can be used as an immobilizing agent for Cd in the dry soil and Ni in the wet soil; however, it might be used as mobilizing agent for Cd in the wet soil and Ni in the dry soil. Sulfur (with rate 2.5%) can be used for enhancing the phyto-extraction of Cd and Ni (especially Cd) from contaminated alkaline soils.

Nitrate isotopes illuminate the black box of paddy soil biogeochemistry: water and carbon management control nitrogen sources and sinks

NASA Astrophysics Data System (ADS)

Wells, N. S.; Clough, T. J.; Johnson-Beebout, S. E.; Buresh, R. J.

2010-12-01

Accurate prediction of the available nitrogen (N) pool in submerged paddy soils is needed in order to produce rice, one of the world’s most essential crops, in an economically and environmentally sustainable manner. By applying emerging nitrate dual-isotope (δ15N- δ18O- NO3-) techniques to paddy systems, we were able to obtain a unique process-level quantification of the synergistic impacts of carbon (C) and water management on N availability. Soil and water samples were collected from fallow experimental plots, with or without organic C amendments, that were maintained under 1 of 3 different hydrologic regimens: continuously submerged, water excluded, or alternate wetting and drying. In continuously submerged soils the δ15N-NO3- : δ18O-NO3- signal of denitrification was not present, indicating that there was no N attenuation. Biological nitrogen fixation (BNF) was the dominant factor in defining the available N pool under these conditions, with δ15N-NO3- approaching atmospheric levels as size of the pool increased. Using an isotope-based pool-mixing model, it was calculated that 10±2 µg N g-1 soil were contributed by BNF during the fallow. A lack of BNF combined with removal via denitrification (δ15N-NO3- : δ18O-NO3- = 1) caused relatively lower available N levels in dried and alternate wetting-drying soils during this period. Magnitude and net impact of denitrification was defined by the extent of drying and C availability, with rice straw C additions driving tighter coupling of nitrification and denitrification (δ15N:δ18O <1). However, despite high rates of attenuation during wetting events, soils that had been completely dried and received straw amendments ultimately retained a significantly larger available N pool due to enhanced input from soil organic matter. These findings underline the necessity of, and validate a new means for, accurate quantification micro-scale biogeochemical interactions for developing farm-scale management practices that can maximize N storage and minimize environmentally undesirable losses.

Improved detection of multiple environmental antibiotics through an optimized sample extraction strategy in liquid chromatography-mass spectrometry analysis.

PubMed

Yi, Xinzhu; Bayen, Stéphane; Kelly, Barry C; Li, Xu; Zhou, Zhi

2015-12-01

A solid-phase extraction/liquid chromatography/electrospray ionization/multi-stage mass spectrometry (SPE-LC-ESI-MS/MS) method was optimized in this study for sensitive and simultaneous detection of multiple antibiotics in urban surface waters and soils. Among the seven classes of tested antibiotics, extraction efficiencies of macrolides, lincosamide, chloramphenicol, and polyether antibiotics were significantly improved under optimized sample extraction pH. Instead of only using acidic extraction in many existing studies, the results indicated that antibiotics with low pK a values (<7) were extracted more efficiently under acidic conditions and antibiotics with high pK a values (>7) were extracted more efficiently under neutral conditions. The effects of pH were more obvious on polar compounds than those on non-polar compounds. Optimization of extraction pH resulted in significantly improved sample recovery and better detection limits. Compared with reported values in the literature, the average reduction of minimal detection limits obtained in this study was 87.6% in surface waters (0.06-2.28 ng/L) and 67.1% in soils (0.01-18.16 ng/g dry wt). This method was subsequently applied to detect antibiotics in environmental samples in a heavily populated urban city, and macrolides, sulfonamides, and lincomycin were frequently detected. Antibiotics with highest detected concentrations were sulfamethazine (82.5 ng/L) in surface waters and erythromycin (6.6 ng/g dry wt) in soils. The optimized sample extraction strategy can be used to improve the detection of a variety of antibiotics in environmental surface waters and soils.

Occurrence of perchlorate in groundwater, paired farmland soil, lettuce, and rhizosphere soil from Chengdu, China.

PubMed

Tang, Yulu; Zhong, Bifeng; Qu, Bing; Feng, Shujin; Ding, Sanglan; Su, Shijun; Li, Zhi; Gan, Zhiwei

2017-05-24

A total of 28 groundwater, paired farmland soil, lettuce, and its rhizosphere soil samples were collected from Chengdu, China to detect perchlorate levels and to evaluate the relationships of perchlorate concentrations among these matrices. The perchlorate concentrations in the groundwater, farmland soil, lettuce, and rhizosphere soil samples ranged from below detection limit to 60.2 μg L -1 , from below detection limit to 249 μg kg -1 dry weight (dw), from 2.07 to 1010 μg kg -1 wet weight, and from below detection limit to 314 μg kg -1 dw, respectively. Significant correlation was found in the perchlorate levels among the farmland soil, lettuce, and rhizosphere soil, suggesting that they have common pollution sources, or perchlorate might transfer from farmland soil-rhizosphere soil-plant. However, there is no significant correlation between groundwater and the other three matrices, indicating that infiltration from perchlorate contaminated farmland soil was not the predominant source for groundwater pollution in Chengdu. The perchlorate concentrations in the farmland soil and lettuce samples were significantly higher than those in the rhizosphere soil, primarily due to uptake of perchlorate through the rhizosphere micro-environment by lettuce, or accelerated degradation by rhizospheric microorganisms, which contributed more needs further investigation.

Similarity index between irrigation water and soil saturation extract in the experimental field of Yachay University, Ecuador

NASA Astrophysics Data System (ADS)

Carrera-Villacrés, D. V.; Sánchez-Gómez, V. P.; Portilla-Bravo, O. A.; Bolaños-Guerrón, D. R.

2017-08-01

Soil monitoring is a job that demands a lot of time and money. therefore, measuring the same parameters in the water becomes simple because it can be done in situ. The objective of this work was to find a similarity index for the validation of mathematical correlation models based on physicochemical parameters to verify if there is a balance between irrigation water and soil saturation extract in the experimental field Yachay that is known as the city of knowledge that is located in Imbabura province, Ecuador, for which, the sampling of water was carried out in two representative periods (dry and rainy). Sampling of 10 soil profiles was also performed, covering the total area; these samples were obtained results of Electrical Conductivity (EC), pH and total dissolved salts (TDS). With correlation models between soils and water, it is possible to predict concentrations of elements in the irrigation water. It was concluded that there is a balance between soil and water, so that the salts present in the soil are highly soluble, in addition, there is a high probability that the elements in the irrigation water are in the soil. In sample water, the same concentrations were found in the soil, at their saturation point, and very close to the field capacity.

Microbial community dynamics and methane, carbon dioxide, oxygen, and nitrous oxide concentrations in upland forest and riparian soils across a seasonal gradient of fully saturated soils to completely dried soils

NASA Astrophysics Data System (ADS)

Jones, R. T.; McGlynn, B. L.; McDermott, T.; Dore, J. E.

2015-12-01

Gas concentrations (CH4, CO2, N2O, and O2), soil properties (soil water content and pH), and microbial community composition were measured from soils at 32 sites across the Stringer Creek Watershed in the Tenderfoot Creek Experimental Forest 7 times between June 3, 2013 and September 20, 2013. Soils were fully saturated during the initial sampling period and dried down over the course of the summer. Soils and gas were sampled from 5cm and 20cm at each site and also at 50cm at eight riparian sites. In total, 496 individual soil samples were collected. Soil moisture ranged from 3.7% to fully saturated; soil pH ranged from 3.60 to 6.68. Methane concentrations in soils ranged from 0.426 ppm to 218 ppm; Carbon dioxide concentrations ranged from 550 ppm to 42,990 ppm; Nitrous oxide concentrations ranged from 0.220 ppm to 2.111 ppm; Oxygen concentrations ranged from 10.2% to 21.5%. Soil microbial communities were characterized by DNA sequences covering the V4 region of the 16S rRNA gene. DNA sequences were generated (~30,000,000 sequences) from the 496 soil samples using the Illumina MiSeq platform. Operational Taxonomic Units were generated using USEARCH, and representative sequences were taxonomically classified according the Ribosomal Database Project's taxonomy scheme. Analysis of similarity revealed that microbial communities found within a landscape type (high upland forest, low upland forest, riparian) were more similar than among landscape types (R = 0.600; p<0.001). Similarly, communities from unique site x depths were similar across the 7 collection periods (R = 0.646; p<0.001) despite changes in soil moisture. Euclidean distances of soil properties and gas concentrations were compared to Bray-Curtis community dissimilarity matrices using Mantel tests to determine how community structure co-varies with the soil environment and gas concentrations. All variables measured significantly co-varied with microbial community membership (pH: R = 0.712, p < 0.001; CO2: R = 0.578, p < 0.001; O2: R = 0.517, p < 0.001; Soil moisture: R = 0.408, p < 0.001; N2O: R = 0.218, p = 0.003; CH4: R = 0.195, p = 0.008). Despite the rather low co-variation between methane concentrations and microbial community composition, relative abundances of methanotrophic and methanogenic lineages did co-vary strongly with methane concentrations.

Effect of different spiking procedures on the distribution and toxicity of ZnO nanoparticles in soil.

PubMed

Waalewijn-Kool, Pauline L; Diez Ortiz, Maria; van Gestel, Cornelis A M

2012-10-01

Due to the difficulty in dispersing some engineered nanomaterials in exposure media, realizing homogeneous distributions of nanoparticles (NP) in soil may pose major challenges. The present study investigated the distribution of zinc oxide (ZnO) NP (30 nm) and non-nano ZnO (200 nm) in natural soil using two different spiking procedures, i.e. as dry powder and as suspension in soil extract. Both spiking procedures showed a good recovery (>85 %) of zinc and based on total zinc concentrations no difference was found between the two spiking methods. Both spiking procedures resulted in a fairly homogeneous distribution of the ZnO particles in soil, as evidenced by the low variation in total zinc concentration between replicate samples (<12 % in most cases). Survival of Folsomia candida in soil spiked at concentrations up to 6,400 mg Zn kg(-1) d.w. was not affected for both compounds. Reproduction was reduced in a concentration-dependent manner with EC50 values of 3,159 and 2,914 mg Zn kg(-1) d.w. for 30 and 200 nm ZnO spiked as dry powder and 3,593 and 5,633 mg Zn kg(-1) d.w. introduced as suspension. Toxicity of ZnO at 30 and 200 nm did not differ. We conclude that the ZnO particle toxicity is not size related and that the spiking of the soil with ZnO as dry powder or as a suspension in soil extract does not affect its toxicity to F. candida.

Phytoextraction of heavy metals by Sesuvium portulacastrum l. a salt marsh halophyte from tannery effluent.

PubMed

Ayyappan, Durai; Sathiyaraj, Ganesan; Ravindran, Konganapuram Chellappan

2016-01-01

The present study investigated the sources for remediation of heavy metals and salts from tannery effluent using salt marsh halophyte Sesuvium portulacastrum. From the results observed, in tannery effluent treated soil from 1 kg dry weight of plant sample, Sesuvium portulacastrum accumulated 49.82 mg Cr, 22.10 mg Cd, 35.10 mg Cu and 70.10 mg Zn and from 1 g dry weight of the plant sample, 246.21 mg Na Cl. Cultivation of Sesuvium portulacastrum significantly reduced the EC, pH and SAR levels in tannery effluent and salt treated soil and correspondingly increased in plant sample after 125 days of cultivation. In conclusion, Sesuvium portulacastrum was an efficient in accumulating heavy metals such as Chromium, Cadmium, Copper and Zinc, sodium and chloride maximum through its leaves when compared to stem and root. The finding of these bioacccumulation studies indicates that Sesuvium portulacastrum could be used for phytoremediation of tannery effluent contaminated field.

Evaluation of soil quality indicators in paddy soils under different crop rotation systems

NASA Astrophysics Data System (ADS)

Nadimi-Goki, Mandana; Bini, Claudio; Haefele, Stephan; Abooei, Monireh

2013-04-01

Evaluation of soil quality indicators in paddy soils under different crop rotation systems Soil quality, by definition, reflects the capacity to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health. Soil quality assessment is an essential issue in soil management for agriculture and natural resource protection. This study was conducted to detect the effects of four crop rotation systems (rice-rice-rice, soya-rice-rice, fallow-rice and pea-soya-rice) on soil quality indicators (soil moisture, porosity, bulk density, water-filled pore space, pH, extractable P, CEC, OC, OM, microbial respiration, active carbon) in paddy soils of Verona area, Northern Italy. Four adjacent plots which managed almost similarly, over five years were selected. Surface soil samples were collected from each four rotation systems in four times, during growing season. Each soil sample was a composite of sub-samples taken from 3 points within 350 m2 of agricultural land. A total of 48 samples were air-dried and passed through 2mm sieve, for some chemical, biological, and physical measurements. Statistical analysis was done using SPSS. Statistical results revealed that frequency distribution of most data was normal. The lowest CV% was related to pH. Analysis of variance (ANOVA) and comparison test showed that there are significant differences in soil quality indicators among crop rotation systems and sampling times. Results of multivariable regression analysis revealed that soil respiration had positively correlation coefficient with soil organic matter, soil moisture and cation exchange capacity. Overall results indicated that the rice rotation with legumes such as bean and soybean improved soil quality over a long time in comparison to rice-fallow rotation, and this is reflected in rice yield. Keywords: Soil quality, Crop Rotation System, Paddy Soils, Italy

Lead levels of edibles grown in contaminated residential soils: a field survey.

PubMed

Finster, Mary E; Gray, Kimberly A; Binns, Helen J

2004-03-29

Plants grown in lead contaminated soils can accumulate lead from the adherence of dust and translocation into the plant tissue. In order to evaluate the potential health hazard due to the consumption of plants grown in residential gardens contaminated by lead, a survey of the lead concentrations in a typical array of edible vegetables, fruits and herbs was conducted. Samples of garden plants harvested from the field were washed with detergent or water alone to remove adhered soil. They were dried, separated into sections including root, shoot and edible fruit, and then analyzed for lead content using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Soil samples, taken in conjunction with the plant harvesting, were analyzed using flame atomic absorbance (FAA). A pattern of lead transference from soil through the root to the stem and leaves of garden crops was found. The majority of the lead was concentrated in the roots (root:soil ranging from 0.02 to 0.51), with some translocation into the shoots (shoot:soil as high as 0.10). This pattern is a concern particularly for crops in which the root, stems, stalks or leaves are edible. The lead concentration in fruiting vegetables was less than the detection limit of 10 ppm (microgram lead/gram dry plant matter). Some edible portions of the leafy vegetables and herbs, however, were found to have lead levels that, if consumed, could contribute to the total body burden of lead. Therefore, urban gardeners should test the lead levels in their soils and develop strategies to ensure safety.

Soil tension mediates isotope fractionation during soil water evaporation

NASA Astrophysics Data System (ADS)

Gaj, Marcel; McDonnell, Jeffrey

2017-04-01

Isotope tracing of the water cycle is increasing in its use and usefulness. Many new studies are extracting soil waters and relating these to streamflow, groundwater recharge and plant transpiration. Nevertheless, unlike isotope fractionation factors from open water bodies, soil water fractionation factors are poorly understood and until now, only empirically derived. In contrast to open water evaporation where temperature, humidity and vapor pressure gradient define fractionation (as codified in the well-known Craig and Gordon model), soil water evaporation includes additionally, fractionation by matrix effects. There is yet no physical explanation of kinetic and equilibrium fraction from soil water within the soil profile. Here we present a simple laboratory experiment with four admixtures of soil grain size (from sand to silt to clay). Oven-dried samples were spiked with water of known isotopic composition at different soil water contents. Soils were then stored in sealed bags and the headspace filled with dry air and allowed to equilibrate for 24hours. Isotopic analysis of the headspace vapor was done with a Los Gatos Inc. water vapor isotope analyzer. Soil water potential of subsamples were measured with a water potential meter. We show for the first time that soil tension controls isotope fractionation in the resident soil water. Below a Pf 3.5 the δ-values of 18O and 2H of the headspace vapor is more positive and increases with increasing soil water potential. Surprisingly, we find that the relationship between soil tension and equilibrium fractionation is independent of soil type. However, δ-values of each soil type plot along a distinct evaporation line. These results indicate that equilibrium fractionation is affected by soil tension in addition to temperature. Therefore, at high soil water tension (under dry conditions) equilibrium fractionation is not consistent with current empirical formulations that ignore these effects. These findings may have implications for plant water uptake studies since plant root water uptake imparts tension to extract water from the soil matrix. Since this is the same physical force as soil water potential, root water uptake at high soil water potential might cause fractionation of soil water. Our work is ongoing to examine these knock-on effects.

Can differences in root responses to soil drying and compaction explain differences in performance of trees growing on landfill sites?

PubMed

Liang, Jiansheng; Zhang, Jianhua; Chan, Gilbert Y. S.; Wong, M. H.

1999-07-01

Two tropical woody species, Acacia confusa Merrill and Litsea glutinosa (Lour.) C.B. Robinson, were grown under controlled conditions in PVC pipes filled with John Innes No. 2 soil. To investigate root distribution, physiological characteristics and hydraulic conductivity, four soil treatments were imposed-well-watered and noncompacted (control), well-watered and compacted; unwatered and noncompacted, and unwatered and compacted. In L. glutinosa, rooting depth and root elongation were severely restricted when soil bulk density increased from around 1.12 to 1.62 g cm(-3), whereas soil compaction had little effect on these parameters in A. confusa. As soil drying progressed, root water potential and osmotic potential declined more slowly in L. glutinosa than in A. confusa. Both the soil drying and compaction treatments significantly stimulated the accumulation of root abscisic acid (ABA) in both species. Soil drying damaged the root cell membrane of A. confusa, but had little influence on the root cell membrane of L. glutinosa. Soil drying had a greater effect on root hydraulic conductivity (L(p)) in L. glutinosa than in A. confusa, whereas the effect of soil compaction on L(p) was less in L. glutinosa than in A. confusa. Soil drying enhanced the effects of soil compaction on root L(p). We conclude that soil drying and compaction have large species-specific effects on the distribution, growth and physiology of roots. The relationships of these root properties to the species' ability to tolerate unfavorable soil conditions were examined.

Tunneling behavior of the formosan subterranean termite (isoptera: rhinotermitadae) in dry soil

USDA-ARS?s Scientific Manuscript database

This study examines the effect of dry soil on tunnel construction by the Formosan subterranean termite, Cptotermes formosanus. Termites did not construct tunnels in dry soil in any of the treatments. Termites only constructed tunnels in moist areas in treatments where the soil was partially moistene...

EXTRACTION METHODS FOR RECOVERY OF VOLATILE ORGANIC COMPOUNDS FROM FORTIFIED DRY SOILS

EPA Science Inventory

Recovery of 8 volatile organic compounds (VOCs) from dry soils, each fortified at 800 ng/g soil, was studied in relation to the extraction method and time of extraction. Extraction procedures studied on desiccator-dried soils were modifications of EPA low-and high-level purge-and...

Nitrous oxide fluxes and nitrogen cycling along a pasturechronosequence in Central Amazonia, Brazil

Treesearch

B. Wick; E. Veldkamp; W. Z. de Mello; M. Keller; P. Crill

2005-01-01

We studied nitrous oxide (N2O) fluxes and soil nitrogen (N) cycling following forest conversion to pasture in the central Amazon near Santarém, Pará, Brazil. Two undisturbed forest sites and 27 pasture sites of 0.5 to 60 years were sampled once each during wet and dry seasons. In addition to soil-atmosphere fluxes of N...

Exposure of school children to polycyclic aromatic hydrocarbons, heavy metals and radionuclides in the urban soil of Kragujevac city, Central Serbia.

PubMed

Stajic, J M; Milenkovic, B; Pucarevic, M; Stojic, N; Vasiljevic, I; Nikezic, D

2016-03-01

The concentrations of radionuclides, polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured in soil samples collected from school backyards and playgrounds in Kragujevac, one of the largest cities of Central Serbia. The activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs were determined using the HPGe semiconductor detector. The average values were 34.6, 44.7, 428.9 and 45.1 Bq kg(-1), respectively. The correlation between the activity concentrations of (226)Ra in the soil samples and the results of the previous measurement of (222)Rn concentrations in the indoor air was examined. The absorbed dose rates, the annual effective doses and excess lifetime cancer risk were also estimated. The activity concentrations of (226)Ra and (232)Th have shown normal distribution. The collected soil samples were analysed for PAHs by HPLC. All analysed soil samples contained PAHs, and their total amounts (for 15 measured compounds) were found to be between 0.038 and 3.136 mg kg(-1) of absolutely dry soil (a.d.s). In addition the concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured in the fourteen soil samples collected from the playgrounds of kindergartens. Copyright © 2015 Elsevier Ltd. All rights reserved.

OBSERVATIONS AND ANALYSIS OF MERCURY IN THE TOP SOIL WITHIN A 100-METER RADIUS OF A CHLORALKALI PLANT IN NORTHER KAZAKHSTAN USING EPA METHOD 7473

EPA Science Inventory

This limited study has shown a comparison of mercury concentrations at different sample collection locations at the chlor-alkali plant in Northern Kazakhstan. Method 7473 uses a direct mercury analyzer for Hg in solid samples. A small amount of sample is dried and combusted. The ...

Visualizing Rhizosphere Soil Structure Around Living Roots

NASA Astrophysics Data System (ADS)

Menon, M.; Berli, M.; Ghezzehei, T. A.; Nico, P.; Young, M. H.; Tyler, S. W.

2008-12-01

The rhizosphere, a thin layer of soil (0 to 2 mm) surrounding a living root, is an important interface between bulk soil and plant root and plays a critical role in root water and nutrient uptake. In this study, we used X-ray Computerized Microtomography (microCT) to visualize soil structure around living roots non-destructively and with high spatial resolution. Four different plant species (Helianthus annuus, Lupinus hartwegii, Vigna radiata and Phaseolus lunatus), grown in four different porous materials (glass beads, medium and coarse sand, loam aggregates), were scanned with 10 ìm spatial resolution, using the microtomography beamline 8.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA. Sample cross section images clearly show contacts between roots and soil particles, connecting water films, air-water interfaces as well as some cellular features of the plants taproots. We found with a simulation experiment, inflating a cylindrical micro-balloon in a pack of air-dry loam aggregates, that soil fracturing rather than compaction might occur around a taproot growing in dry soil. Form these preliminary experiments, we concluded that microCT has potential as a tool for a more process-based understanding of the role of rhizosphere soil structure on soil fertility, plant growth and the water balance at the earth-atmosphere interface.

Characterization of the biosolids composting process by hyperspectral analysis.

PubMed

Ilani, Talli; Herrmann, Ittai; Karnieli, Arnon; Arye, Gilboa

2016-02-01

Composted biosolids are widely used as a soil supplement to improve soil quality. However, the application of immature or unstable compost can cause the opposite effect. To date, compost maturation determination is time consuming and cannot be done at the composting site. Hyperspectral spectroscopy was suggested as a simple tool for assessing compost maturity and quality. Nevertheless, there is still a gap in knowledge regarding several compost maturation characteristics, such as dissolved organic carbon, NO3, and NH4 contents. In addition, this approach has not yet been tested on a sample at its natural water content. Therefore, in the current study, hyperspectral analysis was employed in order to characterize the biosolids composting process as a function of composting time. This goal was achieved by correlating the reflectance spectra in the range of 400-2400nm, using the partial least squares-regression (PLS-R) model, with the chemical properties of wet and oven-dried biosolid samples. The results showed that the proposed method can be used as a reliable means to evaluate compost maturity and stability. Specifically, the PLS-R model was found to be an adequate tool to evaluate the biosolids' total carbon and dissolved organic carbon, total nitrogen and dissolved nitrogen, and nitrate content, as well as the absorbance ratio of 254/365nm (E2/E3) and C/N ratios in the dry and wet samples. It failed, however, to predict the ammonium content in the dry samples since the ammonium evaporated during the drying process. It was found that in contrast to what is commonly assumed, the spectral analysis of the wet samples can also be successfully used to build a model for predicting the biosolids' compost maturity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ecological and human health risk assessment of heavy metal contamination in soil of a municipal solid waste dump in Uyo, Nigeria.

PubMed

Ihedioha, J N; Ukoha, P O; Ekere, N R

2017-06-01

The study assessed the levels of some heavy metals in soils in the vicinity of a municipal solid waste dumpsite with a view to providing information on the extent of contamination, ecological risk of metals in the soils and human health risk to the residents in Uyo. Soil samples were collected in rainy and dry seasons and analyzed for metals (Pb, Cd, Zn, Mn, Cr, Ni and Fe) using atomic absorption spectrometry. The concentrations of heavy metals (mg/kg) at the dumpsite in rainy season were Pb (9.90), Zn (137), Ni (12.56), Cr (3.60), Cd (9.05) and Mn (94.00), while in dry season, the concentrations were Pb (11.80), Zn (146), Ni (11.82), Cr (4.05), Cd (12.20) and Mn (91.20). The concentrations of metals in the studied sites were higher than that of the control site (P < 0.05). Pollution indices studies revealed that soil samples from dumpsite and distances from 10 and 20 m east of the dumpsite were highly polluted with cadmium. Ecological risk assessment carried out showed that cadmium contributed 98-99 % of the total potentially ecological risk. No probable health risk was observed as the total hazard index of all the metals was less than one. However, children were found to be more susceptible to heavy metal contamination than adult.

McMurdo Dry Valleys, Antarctica - A Mars Phoenix Mission Analog

NASA Technical Reports Server (NTRS)

Tamppari, L. K.; Anderson, R. M.; Archer, D.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Ming, Douglas W.; Moore, Q.; Quinn, J. E.; Smith, P. H.;

Testing of the Prototype Mars Drill and Sample Acquisition System in the Mars Analog Site of the Antarctica's Dry Valleys

NASA Astrophysics Data System (ADS)

Zacny, K.; Paulsen, G.; McKay, C.; Glass, B. J.; Marinova, M.; Davila, A. F.; Pollard, W. H.; Jackson, A.

2011-12-01

We report on the testing of the one meter class prototype Mars drill and cuttings sampling system, called the IceBreaker in the Dry Valleys of Antarctica. The drill consists of a rotary-percussive drill head, a sampling auger with a bit at the end having an integrated temperature sensor, a Z-stage for advancing the auger into the ground, and a sampling station for moving the augered ice shavings or soil cuttings into a sample cup. In November/December of 2010, the IceBreaker drill was tested in the Uni-versity Valley (within the Beacon Valley region of the Antarctic Dry Valleys). University Valley is a good analog to the Northern Polar Regions of Mars because a layer of dry soil lies on top of either ice-cemeted ground or massive ice (depending on the location within the valley). That is exactly what the 2007 Phoenix mission discovered on Mars. The drill demonstrated drilling in ice-cemented ground and in massive ice at the 1-1-100-100 level; that is the drill reached 1 meter in 1 hour with 100 Watts of power and 100 Newton Weight on Bit. This corresponds to an average energy of 100 Whr. At the same time, the bit temperature measured by the bit thermocouple did not exceed more than 10 °C above the formation temperature. The temperature also never exceeded freezing, which minimizes chances of getting stuck and also of altering the materials that are being sampled and analyzed. The samples in the forms of cuttings were acquired every 10 cm intervals into sterile bags. These tests have shown that drilling on Mars, in ice cemented ground with limited power, energy and Weight on Bit, and collecting samples in discrete depth intervals is possible within the given mass, power, and energy levels of a Phoenix-size lander and within the duration of a Phoenix-like mission.

Influence of soil moisture on soil respiration

NASA Astrophysics Data System (ADS)

Fer, Miroslav; Kodesova, Radka; Nikodem, Antonin; Klement, Ales; Jelenova, Klara

2015-04-01

The aim of this work was to describe an impact of soil moisture on soil respiration. Study was performed on soil samples from morphologically diverse study site in loess region of Southern Moravia, Czech Republic. The original soil type is Haplic Chernozem, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). Soil samples were collected from topsoils at 5 points of the selected elevation transect and also from the parent material (loess). Grab soil samples, undisturbed soil samples (small - 100 cm3, and large - 713 cm3) and undisturbed soil blocks were taken. Basic soil properties were determined on grab soil samples. Small undisturbed soil samples were used to determine the soil water retention curves and the hydraulic conductivity functions using the multiple outflow tests in Tempe cells and a numerical inversion with HYDRUS 1-D. During experiments performed in greenhouse dry large undisturbed soil samples were wetted from below using a kaolin tank and cumulative water inflow due to capillary rise was measured. Simultaneously net CO2 exchange rate and net H2O exchange rate were measured using LCi-SD portable photosynthesis system with Soil Respiration Chamber. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program was applied to modify selected soil hydraulic parameters for particular conditions and to simulate actual soil water distribution within each soil column in selected times. Undisturbed soil blocks were used to prepare thin soil sections to study soil-pore structure. Results for all soil samples showed that at the beginning of soil samples wetting the CO2 emission increased because of improving condition for microbes' activity. The maximum values were reached for soil column average soil water content between 0.10 and 0.15 cm3/cm3. Next CO2 emission decreased since the pore system starts filling by water (i.e. aggravated conditions for microbes, closing soil gas pathways etc.). In the case of H2O exchange rate, values increased with increasing soil water contents (up to 0.15-0.20 cm3/cm3) and then remained approximately constant. Acknowledgement: Authors acknowledge the financial support of the Ministry of Agriculture of the Czech Republic No. QJ1230319

Pore-scale water dynamics during drying and the impacts of structure and surface wettability

NASA Astrophysics Data System (ADS)

Cruz, Brian C.; Furrer, Jessica M.; Guo, Yi-Syuan; Dougherty, Daniel; Hinestroza, Hector F.; Hernandez, Jhoan S.; Gage, Daniel J.; Cho, Yong Ku; Shor, Leslie M.

2017-07-01

Plants and microbes secrete mucilage into soil during dry conditions, which can alter soil structure and increase contact angle. Structured soils exhibit a broad pore size distribution with many small and many large pores, and strong capillary forces in narrow pores can retain moisture in soil aggregates. Meanwhile, contact angle determines the water repellency of soils, which can result in suppressed evaporation rates. Although they are often studied independently, both structure and contact angle influence water movement, distribution, and retention in soils. Here drying experiments were conducted using soil micromodels patterned to emulate different aggregation states of a sandy loam soil. Micromodels were treated to exhibit contact angles representative of those in bulk soil (8.4° ± 1.9°) and the rhizosphere (65° ± 9.2°). Drying was simulated using a lattice Boltzmann single-component, multiphase model. In our experiments, micromodels with higher contact angle surfaces took 4 times longer to completely dry versus micromodels with lower contact angle surfaces. Microstructure influenced drying rate as a function of saturation and controlled the spatial distribution of moisture within micromodels. Lattice Boltzmann simulations accurately predicted pore-scale moisture retention patterns within micromodels with different structures and contact angles.

Wet and dry atmospheric depositions of inorganic nitrogen during plant growing season in the coastal zone of Yellow River Delta.

PubMed

Yu, Junbao; Ning, Kai; Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei; Gao, Yongjun

2014-01-01

The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 (2-) and Na(+) were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m(-2), in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 (-)-N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 (+)-N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 (-)-N and NH4 (+)-N was ~31.38% and ~20.50% for the contents of NO3 (-)-N and NH4 (+)-N in 0-10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.

Influence of smectite hydration and swelling on atrazine sorption behavior.

PubMed

Chappell, Mark A; Laird, David A; Thompson, Michael L; Li, Hui; Teppen, Brian J; Aggarwal, Vaneet; Johnston, Cliff T; Boyd, Stephen A

2005-05-01

Smectites, clay minerals commonly found in soils and sediments, vary widely in their ability to adsorb organic chemicals. Recent research has demonstrated the importance of surface charge density and properties of exchangeable cations in controlling the affinity of smectites for organic molecules. In this study, we induced hysteresis in the crystalline swelling of smectites to test the hypothesis that the extent of crystalline swelling (or interlayer hydration status) has a large influence on the ability of smectites to adsorb atrazine from aqueous systems. Air-dried K-saturated Panther Creek (PC) smectite swelled less (d(001) = 1.38 nm) than never-dried K-PC (d(001) = 1.7 nm) when rehydrated in 20 mM KCl. Correspondingly, the air-dried-rehydrated K-PC had an order of magnitude greater affinity for atrazine relative to the never-dried K-PC. Both air-dried-rehydrated and never-dried Ca-PC expanded to approximately 2.0 nm in 10 mM CaCl2 and both samples had similar affinities for atrazine that were slightly lower than that of never-dried K-PC. The importance of interlayer hydration status in controlling sorption affinity was confirmed by molecular modeling, which revealed much greater interaction between interlayer water molecules and atrazine in a three-layer hydrate relative to a one-layer hydrate. The entropy change on moving atrazine from a fully hydrated state in the bulk solution to a partially hydrated state in the smectite interlayers is believed to be a major factor influencing sorption affinity. In an application test, choice of background solution (20 mM KCl versus 10 mM CaCl2) and air-drying treatments significantly affected atrazine sorption affinities for three-smectitic soils; however, the trends were not consistent with those observed for the reference smectite. Further, extending the initial rehydration time from 24 to 240 h (prior to adding atrazine) significantly decreased the soil's sorption affinity for atrazine. We conclude that interlayer hydration status has a large influence on the affinity of smectites for atrazine and that air-drying treatments have the potential to modify the sorption affinity of smectitic soils for organic molecules such as atrazine.

Canadian Field Soils IV: Modeling Thermal Conductivity at Dryness and Saturation

NASA Astrophysics Data System (ADS)

Tarnawski, V. R.; McCombie, M. L.; Leong, W. H.; Coppa, P.; Corasaniti, S.; Bovesecchi, G.

2018-03-01

The thermal conductivity data of 40 Canadian soils at dryness (λ _{dry}) and at full saturation (λ _{sat}) were used to verify 13 predictive models, i.e., four mechanistic, four semi-empirical and five empirical equations. The performance of each model, for λ _{dry} and λ _{sat}, was evaluated using a standard deviation ( SD) formula. Among the mechanistic models applied to dry soils, the closest λ _{dry} estimates were obtained by MaxRTCM (it{SD} = ± 0.018 Wm^{-1}\\cdot K^{-1}), followed by de Vries and a series-parallel model (S-{\\vert }{\\vert }). Among the semi-empirical equations (deVries-ave, Advanced Geometric Mean Model (A-GMM), Chaudhary and Bhandari (C-B) and Chen's equation), the closest λ _{dry} estimates were obtained by the C-B model (± 0.022 Wm^{-1}\\cdot K^{-1}). Among the empirical equations, the top λ _{dry} estimates were given by CDry-40 (± 0.021 Wm^{-1}\\cdot K^{-1} and ± 0.018 Wm^{-1}\\cdot K^{-1} for18-coarse and 22-fine soils, respectively). In addition, λ _{dry} and λ _{sat} models were applied to the λ _{sat} database of 21 other soils. From all the models tested, only the maxRTCM and the CDry-40 models provided the closest λ _{dry} estimates for the 40 Canadian soils as well as the 21 soils. The best λ _{sat} estimates for the 40-Canadian soils and the 21 soils were given by the A-GMM and the S-{\\vert }{\\vert } model.

Effects of Moisture and Particle Size on Quantitative Determination of Total Organic Carbon (TOC) in Soils Using Near-Infrared Spectroscopy.

PubMed

Tamburini, Elena; Vincenzi, Fabio; Costa, Stefania; Mantovi, Paolo; Pedrini, Paola; Castaldelli, Giuseppe

2017-10-17

Near-Infrared Spectroscopy is a cost-effective and environmentally friendly technique that could represent an alternative to conventional soil analysis methods, including total organic carbon (TOC). Soil fertility and quality are usually measured by traditional methods that involve the use of hazardous and strong chemicals. The effects of physical soil characteristics, such as moisture content and particle size, on spectral signals could be of great interest in order to understand and optimize prediction capability and set up a robust and reliable calibration model, with the future perspective of being applied in the field. Spectra of 46 soil samples were collected. Soil samples were divided into three data sets: unprocessed, only dried and dried, ground and sieved, in order to evaluate the effects of moisture and particle size on spectral signals. Both separate and combined normalization methods including standard normal variate (SNV), multiplicative scatter correction (MSC) and normalization by closure (NCL), as well as smoothing using first and second derivatives (DV1 and DV2), were applied to a total of seven cases. Pretreatments for model optimization were designed and compared for each data set. The best combination of pretreatments was achieved by applying SNV and DV2 on partial least squares (PLS) modelling. There were no significant differences between the predictions using the three different data sets ( p < 0.05). Finally, a unique database including all three data sets was built to include all the sources of sample variability that were tested and used for final prediction. External validation of TOC was carried out on 16 unknown soil samples to evaluate the predictive ability of the final combined calibration model. Hence, we demonstrate that sample preprocessing has minor influence on the quality of near infrared spectroscopy (NIR) predictions, laying the ground for a direct and fast in situ application of the method. Data can be acquired outside the laboratory since the method is simple and does not need more than a simple band ratio of the spectra.

What is the story that soil tells us? Environmental and anthropogenic change

NASA Astrophysics Data System (ADS)

Shanskiy, Merrit; Kriiska, Aivar; Oras, Ester

2015-04-01

The archaeological studies have shown the evidence of human impact on soils functioning. On the other hand, the changed conditions of normal soil functioning will influence the human settlement in specific area. This study is part of a wider archaeological project on the environmental studies of the Kohtla Iron Age sacrificial site. To obtain a data about soil cover around historical finding some 1500 years ago, special sampling and research were carried out at the study site located in Kohtla Vanaküla, northeastern Estonia where a valuable collection of metal weapons and tools was discovered. The aim of current study was to analyze the site-specific soils to find out the connections between soil records and human mediated historical land degradation. Also, the site specific conditions were studied in order to understand its impact on archaeological artefacts and their preservation conditions. For the current investigation the soil sampling was carried out in July, 2014. The soils were described based on 20 soil pits. The site-specific soil morphological description was finalized and chemical analyses were performed at the laboratory of Soil Science and Agrochemistry, Estonian University of Life Science. Soil was air dried and passed through a 2- mm sieve. The chemical elements (P, K, Ca, Mg, Fe) were analyzed by using Mehlich 3 extraction by MP-AES analytical performance. Soil pH was measured from the soil suspension with 1M KCl. Ctot was analysed by dry combustion method in a vario MAX CNS elemental analyser (ELEMENTAR, Germany). Organic C was determined with elemental analyzer. According to World Reference Base for Soil Resources (WRB) classification system (FAO, 1998), the soil in the study area belongs to the soils subgroups of Gley soils on yellowish-grey calcareous till. The study area soil cover has strong anthropogenic influence due to different human activities. First, there are agricultural activities in the area. Although the region is currently exploited as grassland for animal grazing, it is known to have been ploughed in the past, resulting in amelioration of this soil type. Second, a result of surrounding oil-shale mining the status of groundwater has been changed as well.

Soil property effects on wind erosion of organic soils

NASA Astrophysics Data System (ADS)

Zobeck, Ted M.; Baddock, Matthew; Scott Van Pelt, R.; Tatarko, John; Acosta-Martinez, Veronica

2013-09-01

Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (OM > 20%) in half or more of the upper 80 cm. Forty two states have a total of 21 million ha of Histosols in the United States. These soils, when intensively cropped, are subject to wind erosion resulting in loss of crop productivity and degradation of soil, air, and water quality. Estimating wind erosion on Histosols has been determined by USDA-Natural Resources Conservation Service (NRCS) as a critical need for the Wind Erosion Prediction System (WEPS) model. WEPS has been developed to simulate wind erosion on agricultural land in the US, including soils with organic soil material surfaces. However, additional field measurements are needed to understand how soil properties vary among organic soils and to calibrate and validate estimates of wind erosion of organic soils using WEPS. Soil properties and sediment flux were measured in six soils with high organic contents located in Michigan and Florida, USA. Soil properties observed included organic matter content, particle density, dry mechanical stability, dry clod stability, wind erodible material, and geometric mean diameter of the surface aggregate distribution. A field portable wind tunnel was used to generate suspended sediment and dust from agricultural surfaces for soils ranging from 17% to 67% organic matter. The soils were tilled and rolled to provide a consolidated, friable surface. Dust emissions and saltation were measured using an isokinetic vertical slot sampler aspirated by a regulated suction source. Suspended dust was sampled using a Grimm optical particle size analyzer. Particle density of the saltation-sized material (>106 μm) was inversely related to OM content and varied from 2.41 g cm-3 for the soil with the lowest OM content to 1.61 g cm-3 for the soil with highest OM content. Wind erodible material and the geometric mean diameter of the surface soil were inversely related to dry clod stability. The effect of soil properties on sediment flux varied among flux types. Saltation flux was adequately predicted with simple linear regression models. Dry mechanical stability was the best single soil property linearly related to saltation flux. Simple linear models with soil properties as independent variables were not well correlated with PM10E values (mass flux). A second order polynomial equation with OM as the independent variable was found to be most highly correlated with PM10E values. These results demonstrate that variations in sediment and dust emissions can be linked to soil properties using simple models based on one or more soil properties to estimate saltation mass flux and PM10E values from organic and organic-rich soils.

Visualizing the impact of living roots on rhizosphere soil structure using X-ray microtomography

NASA Astrophysics Data System (ADS)

Menon, M.; Berli, M.; Ghezzehei, T. A.; Nico, P.; Young, M. H.; Tyler, S. W.

2009-04-01

The rhizosphere is an interface between bulk soil and plant root and plays a critical role in root water and nutrient uptake. In this study, we used X-ray Computerized Microtomography (microCT) to visualize soil structure around living roots non-destructively and with high spatial resolution. Four different plant species (Helianthus annuus, Lupinus hartwegii, Vigna radiata and Phaseolus lunatus), grown in four different porous materials (glass beads, medium and coarse sand, loam aggregates), were scanned with 10 μm spatial resolution, using the microtomography beamline 8.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA. Sample cross section images clearly show contacts between roots and soil particles, connecting water films, air-water interfaces as well as some cellular features of the plants taproots. We found with a simulation experiment, inflating a cylindrical micro-balloon in a pack of air-dry loam aggregates, that soil fracturing rather than compaction might occur around a taproot growing in dry soil. Form these preliminary experiments, we concluded that microCT has potential as a tool for a more process-based understanding of the role of rhizosphere soil structure on soil fertility, plant growth and the water balance at the earth-atmosphere interface.

Dry flue gas desulfurization by-product application effects on plant uptake and soil storage changes in a managed grassland.

PubMed

Burgess-Conforti, Jason R; Brye, Kristofor R; Miller, David M; Pollock, Erik D; Wood, Lisa S

2018-02-01

Environmental regulations mandate that sulfur dioxide (SO 2 ) be removed from the flue gases of coal-fired power plants, which results in the generation of flue gas desulfurization (FGD) by-products. These FGD by-products may be a viable soil amendment, but the large amounts of trace elements contained in FGD by-products are potentially concerning. The objective of this study was to evaluate the effects of land application of a high-Ca dry FGD (DFGD) by-product on trace elements in aboveground biomass and soil. A high-Ca DFGD by-product was applied once at a rate of 9 Mg ha -1 on May 18, 2015 to small plots with mixed-grass vegetation. Soil and biomass were sampled prior to application and several times thereafter. Aboveground dry matter and tissue As, Co, Cr, Hg, Se, U, and V concentrations increased (P < 0.05) following application, but did not differ (P > 0.05) from pre-application levels or the unamended control within 3 to 6 months of application. Soil pH in the amended treatment 6 months after application was greater (P < 0.05) than in the unamended control. Soil Ca, S, and Na contents also increased (P < 0.05), following by-product application compared to the unamended control. High-Ca DFGD by-products appear to be useful as a soil amendment, but cause at least a temporary increase in tissue concentrations of trace elements, which may be problematic for animal grazing situations.

‘Natural background’ soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

NASA Astrophysics Data System (ADS)

Doerr, S. H.; Woods, S. W.; Martin, D. A.; Casimiro, M.

2009-06-01

SummarySoils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites ( n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by collecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were further analyzed for repellency using WDPT and contact angle ( θsl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species ( Pinus ponderosa, Pinus contorta, Picea engelmanii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long-unburnt conifer forest soils of the north-western USA is therefore incorrect. It follows that, where pre-fire water repellency levels are not known or highly variable, post-fire soil water repellency conditions are an unreliable indicator in classifying soil burn severity. The terrain and soil variables examined showed, overall, no convincing relationship with the repellency levels observed ( R2 < 0.15) except that repellency was limited in soils (i) developed over meta-sedimentary lithology and (ii) with clay contents >4%. This suggests that water repellency levels cannot be predicted with confidence from common terrain or soil variables.

'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

USGS Publications Warehouse

Doerr, S.H.; Woods, S.W.; Martin, D.A.; Casimiro, M.

2009-01-01

Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by collecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were further analyzed for repellency using WDPT and contact angle (??sl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelmanii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long-unburnt conifer forest soils of the north-western USA is therefore incorrect. It follows that, where pre-fire water repellency levels are not known or highly variable, post-fire soil water repellency conditions are an unreliable indicator in classifying soil burn severity. The terrain and soil variables examined showed, overall, no convincing relationship with the repellency levels observed (R2 < 0.15) except that repellency was limited in soils (i) developed over meta-sedimentary lithology and (ii) with clay contents >4%. This suggests that water repellency levels cannot be predicted with confidence from common terrain or soil variables. ?? 2009 Elsevier B.V.

Rapid analysis of 2,4-D in soil samples by modified Soxhlet apparatus using HPLC with UV detection.

PubMed

Kashyap, Sanjay M; Pandya, Girish H; Kondawar, Vivek K; Gabhane, Sanjay S

2005-02-01

The 2,4-dichlorophenoxy acetic acid (2,4-D) is used as a systemic herbicide to control broadleaf weeds in wheat, corn, range land/pasture land, sorghum, and barley. In this study, a fast and efficient method is developed by selection of modified extraction apparatus and high-performance liquid chromatography (HPLC)-UV conditions for the determination of 2,4-D in soil samples. The method is applied to the study of soil samples collected from the agricultural field. The herbicide is extracted from soil samples by acetonitrile in a modified Soxhlet apparatus. The advantages of the apparatus are that it uses small volume of organic solvent, reduced time of extraction, and better recovery of the analyte. The extract is filtered using a very fine microfiber paper. The total extract is concentrated in a rotatory evaporator, dried under ultrahigh pure N2, and finally reconstituted in 1 mL of acetonitrile. HPLC-UV at 228 nm is used for analysis. The herbicide is identified and quantitated using the HPLC system. The method is validated by the analysis of spiked soil samples. Recoveries obtained varied from 85% to 100% for spiked soil samples. The limit of quantitation (LOQ) and the limit of detection (LOD) are 0.010 and 0.005 parts per million (ppm), respectively, for spiked soil samples. The LOQ and LOD are 0.006 and 0.003 ppm for unspiked soil samples. The measured concentrations of 2,4-D in spiked soil samples are between 0.010 and 0.020 ppm with an average of 0.016 +/- 0.003 ppm. For unspiked soil samples it is between 0.006 ppm and 0.012 ppm with an average of 0.009 +/- 0.002 ppm. The measured concentrations of 2,4-D in soil samples are generally low and do not exceed the regulatory agencies guidelines.

Advances in spectroscopic methods for quantifying soil carbon

USGS Publications Warehouse

Reeves, James B.; McCarty, Gregory W.; Calderon, Francisco; Hively, W. Dean

2012-01-01

The current gold standard for soil carbon (C) determination is elemental C analysis using dry combustion. However, this method requires expensive consumables, is limited by the number of samples that can be processed (~100/d), and is restricted to the determination of total carbon. With increased interest in soil C sequestration, faster methods of analysis are needed, and there is growing interest in methods based on diffuse reflectance spectroscopy in the visible, near-infrared or mid-infrared spectral ranges. These spectral methods can decrease analytical requirements and speed sample processing, be applied to large landscape areas using remote sensing imagery, and be used to predict multiple analytes simultaneously. However, the methods require localized calibrations to establish the relationship between spectral data and reference analytical data, and also have additional, specific problems. For example, remote sensing is capable of scanning entire watersheds for soil carbon content but is limited to the surface layer of tilled soils and may require difficult and extensive field sampling to obtain proper localized calibration reference values. The objective of this chapter is to discuss the present state of spectroscopic methods for determination of soil carbon.

Dermally adhered soil: 2. Reconstruction of dry-sieve particle-size distributions from wet-sieve data.

PubMed

Choate, LaDonna M; Ranville, James F; Bunge, Annette L; Macalady, Donald L

2006-10-01

In the evaluation of soil particle-size effects on environmental processes, particle-size distributions are measured by either wet or dry sieving. Commonly, size distributions determined by wet and dry sieving differ because some particles disaggregate in water. Whereas the dry-sieve distributions are most relevant to the study of soil adherence to skin, soil can be recovered from skin only by washing with the potential for disaggregation whether or not it is subsequently wet or dry sieved. Thus, the possibility exists that wet-sieving measurements of the particle sizes that adhered to the skin could be skewed toward the smaller fractions. This paper provides a method by which dry-sieve particle-size distributions can be reconstructed from wet-sieve particle-size distributions for the same soil. The approach combines mass balances with a series of experiments in which wet sieving was applied to dry-sieve fractions from the original soil. Unless the soil moisture content is high (i.e., greater than or equal to the water content after equilibration with water-saturated air), only the soil particles of diameters less than about 63 microm adhere to the skin. Because of this, the adhering particle-size distribution calculated using the reconstruction method was not significantly different from the wet-sieving determinations.

Heated fiber optic distributed temperature sensing: a tool for measuring soil water content

NASA Astrophysics Data System (ADS)

Rodriguez-Sinobas, Leonor; Zubelzu, Sergio; Sánchez-Calvo, Raúl; Horcajo, Daniel

2016-04-01

The use of Distributed Fiber Optic Temperature Measurement (DFOT) method for estimating temperature variation along a cable of fiber optic has been assessed in multiple environmental applications. Recently, the application of DFOT combined with an active heating pulses technique has been reported as a sensor to estimate soil moisture. This method applies a known amount of heat to the soil and monitors the temperature evolution, which mainly depends on the soil moisture content . This study presents the application of the Active Heated DFOT method to determine the soil water retention curve under experimental conditions. The experiment was conducted in a rectangular methacrylate box of 2.5 m x 0.25 m x 0.25 m which was introduced in a larger box 2.8 m x 0.3 m x 0.3 m of the same material. The inner box was filled with a sandy loamy soil collected from the nearest garden and dried under ambient temperature for 30 days. Care was taking to fill up the box maintaining the soil bulk density determined "in-situ". The cable was deployed along the box at 10 cm depth. At the beginning of the experiment, the box was saturated bottom-up, by filling the outer box with water, and then it kept dried for two months. The circulation of heated air at the bottom box accelerated the drying process. In addition, fast growing turf was also sowed to dry it fast. The DTS unit was a SILIXA ULTIMA SR (Silixa Ltd, UK) and has spatial and temporal resolution of 0.29 m and 5 s, respectively. In this study, heat pulses of 7 W/m for 2 1/2 min were applied uniformly along the fiber optic cable and the thermal response on an adjacent cable was monitored in different soil water status. Then, the heating and drying phase integer (called Tcum) was determined following the approach of Sayde et al., (2010). For each water status,  was measured by the gravimetric method in several soil samples collected in three box locations at the same depth that the fiber optic cable and after each heat pulse. Finally, the soil water retention curve was estimated by fitting pairs of Tcum- values. Results showed the feasibility of heated fiber optics with distributed temperature sensing to estimate soil water content, and suggest its potential for its application under field conditions

Fast changes in seasonal forest communities due to soil moisture increase after damming.

PubMed

do Vale, Vagner Santiago; Schiavini, Ivan; Araújo, Glein Monteiro; Gusson, André Eduardo; Lopes, Sérgio de Faria; de Oliveira, Ana Paula; do Prado-Júnior, Jamir Afonso; Arantes, Carolina de Silvério; Dias-Neto, Olavo Custodio

2013-12-01

Local changes caused by dams can have drastic consequences for ecosystems, not only because they change the water regime but also the modification on lakeshore areas. Thus, this work aimed to determine the changes in soil moisture after damming, to understand the consequences of this modification on the arboreal community of dry forests, some of the most endangered systems on the planet. We studied these changes in soil moisture and the arboreal community in three dry forests in the Araguari River Basin, after two dams construction in 2005 and 2006, and the potential effects on these forests. For this, plots of 20 m x 10 m were distributed close to the impoundment margin and perpendicular to the dam margin in two deciduous dry forests and one semi-deciduous dry forest located in Southeastern Brazil, totaling 3.6 ha sampled. Besides, soil analysis were undertaken before and after impoundment at three different depths (0-10, 20-30 and 40-50 cm). A tree (minimum DBH of 4.77 cm) community inventory was made before (TO) and at two (T2) and four (T4) years after damming. Annual dynamic rates of all communities were calculated, and statistical tests were used to determine changes in soil moisture and tree communities. The analyses confirmed soil moisture increases in all forests, especially during the dry season and at sites closer to the reservoir; besides, an increase in basal area due to the fast growth of many trees was observed. The highest turnover occurred in the first two years after impoundment, mainly due to the higher tree mortality especially of those closer to the dam margin. All forests showed reductions in dynamic rates for subsequent years (T2-T4), indicating that these forests tended to stabilize after a strong initial impact. The modifications were more extensive in the deciduous forests, probably because the dry period resulted more rigorous in these forests when compared to semideciduous forest. The new shorelines created by damming increased soil moisture in the dry season, making plant growth easier. We concluded that several changes occurred in the T0-T2 period and at 0-30 m to the impoundment, mainly for the deciduous forests, where this community turned into a "riparian-deciduous forest" with large basal area in these patches. However, unlike other transitory disturbances, damming is a permanent alteration and transforms the landscape to a different scenario, probably with major long-term consequences for the environment.

Measurement of particle size distribution of soil and selected aggregate sizes using the hydrometer method and laser diffractometry

NASA Astrophysics Data System (ADS)

Guzmán, G.; Gómez, J. A.; Giráldez, J. V.

2010-05-01

Soil particle size distribution has been traditionally determined by the hydrometer or the sieve-pipette methods, both of them time consuming and requiring a relatively large soil sample. This might be a limitation in situations, such as for instance analysis of suspended sediment, when the sample is small. A possible alternative to these methods are the optical techniques such as laser diffractometry. However the literature indicates that the use of this technique as an alternative to traditional methods is still limited, because the difficulty in replicating the results obtained with the standard methods. In this study we present the percentages of soil grain size determined using laser diffractometry within ranges set between 0.04 - 2000 μm. A Beckman-Coulter ® LS-230 with a 750 nm laser beam and software version 3.2 in five soils, representative of southern Spain: Alameda, Benacazón, Conchuela, Lanjarón and Pedrera. In three of the studied soils (Alameda, Benacazón and Conchuela) the particle size distribution of each aggregate size class was also determined. Aggregate size classes were obtained by dry sieve analysis using a Retsch AS 200 basic ®. Two hundred grams of air dried soil were sieved during 150 s, at amplitude 2 mm, getting nine different sizes between 2000 μm and 10 μm. Analyses were performed by triplicate. The soil sample preparation was also adapted to our conditions. A small amount each soil sample (less than 1 g) was transferred to the fluid module full of running water and disaggregated by ultrasonication at energy level 4 and 80 ml of sodium hexametaphosphate solution during 580 seconds. Two replicates of each sample were performed. Each measurement was made for a 90 second reading at a pump speed of 62. After the laser diffractometry analysis, each soil and its aggregate classes were processed calibrating its own optical model fitting the optical parameters that mainly depends on the color and the shape of the analyzed particle. As a second alternative a unique optical model valid for a broad range of soils developed by the Department of Soil, Water, and Environmental Science of the University of Arizona (personal communication, already submitted) was tested. The results were compared with the particle size distribution measured in the same soils and aggregate classes using the hydrometer method. Preliminary results indicate a better calibration of the technique using the optical model of the Department of Soil, Water, and Environmental Science of the University of Arizona, which obtained a good correlations (r2>0.85). This result suggests that with an appropriate calibration of the optical model laser diffractometry might provide a reliable soil particle characterization.

Interrelationships between soil biota and soil physical properties in forest areas of the Pieniny National Park (Poland)

NASA Astrophysics Data System (ADS)

Józefowska, Agnieszka; Zaleski, Tomasz; Sokołowska, Justyna; Dzierwa, Agata

2017-04-01

The study area was located in the Pieniny National Park (PNP) in the Carpathian Mountain (Southern Poland). Investigated soil belonged to Eutric Cambisols and had silt or silt loam texture. The purpose of this research was to investigated relationship between soil biota, such as microbial activity, soil Oligochaeta (Lumbricidae and Enchytraeidae) and soil physical properties, such as water retention or aggregates stability. This research was conducted at six forest monitoring areas of the PNP. Sampling was collected in the September 2016. For each of the 6 places, undisturbed and disturbed soil samples were taken from the 0-15-cm and 15-30-cm layer in 3 to 5 replicates. Undisturbed soil was taken: i) into Kopecky cylinders to determined soil physical properties; ii) a soil cores to determined enchytraeids and fine roots biomass (RB). Disturbed soil was collected in 3 reps and homogenized. Next such soil samples were divided into three parts: i) fresh one to determined dehydrogenase activity (ADh), microbial carbon biomass (MC) and labile carbon (LC); ii) air-dried, passed through a sieve (2-mm mesh size) and used for analysis: pH, organic carbon and bulk density; iii) last part air dried was used to determined stability of different size aggregates. In field, earthworms were collected in 3 reps using hand sorting method. Investigated soils were strongly acidic to neutral (pH 4.8-6.8). Organic carbon (Corg) content was varied from 0.8% to 4.5% and was higher in 0-15-cm layers than in 15-30-cm layers. Higher Corgcontent was connected with lower bulk density. Enchytraeids density was ranged from 1807 ind. m-2 to 88855 ind. m-2 and was correlated with microbial activity (ADh and MB) and RB. Earthworms density (ED) was ranged from 7 ind. m-2to 507 ind. m-2. In investigated soil was 6 genus and 7 species (Octolasion lacteum, Aporrectodea caliginosa, Aporrectodea rosea, Aporrectodea jassyensis, Lumbricus rubellus, Eisenia lucens, and Fitzingeria platyura depressa). ED was closely related with soil moisture and water field capacity. This Research was financed by the Ministry of Science and Higher Education of the Republic of Poland, No. BM - 4175/16

Formation of iron nanoparticles and increase in iron reactivity in mineral dust during simulated cloud processing.

PubMed

Shi, Zongbo; Krom, Michael D; Bonneville, Steeve; Baker, Alex R; Jickells, Timothy D; Benning, Liane G

2009-09-01

The formation of iron (Fe) nanoperticles and increase in Fe reactivity in mineral dust during simulated cloud processing was investigated using high-resolution microscopy and chemical extraction methods. Cloud processing of dust was experimentally simulated via an alternation of acidic (pH 2) and circumneutral conditions (pH 5-6) over periods of 24 h each on presieved (<20 microm) Saharan soil and goethite suspensions. Microscopic analyses of the processed soil and goethite samples reveal the neo-formation of Fe-rich nanoparticle aggregates, which were not found initially. Similar Fe-rich nanoparticles were also observed in wet-deposited Saharen dusts from the western Mediterranean but not in dry-deposited dust from the eastern Mediterranean. Sequential Fe extraction of the soil samples indicated an increase in the proportion of chemically reactive Fe extractable by an ascorbate solution after simulated cloud processing. In addition, the sequential extractions on the Mediterranean dust samples revealed a higher content of reactive Fe in the wet-deposited dust compared to that of the dry-deposited dust These results suggestthat large variations of pH commonly reported in aerosol and cloud waters can trigger neo-formation of nanosize Fe particles and an increase in Fe reactivity in the dust

Shoot water relations of mature black spruce families displaying a genotype x environment interaction in growth rate. II. Temporal trends and response to varying soil water conditions

Treesearch

John E. Major; Kurt H. Johnsen

1999-01-01

Pressure-volume curves and shoot water potentials were determined for black spruce (Picea mariana (Mill.) BSP) trees from four full-sib families at the Petawawa Research Forest, Ontario, Canada. Trees were sampled from a dry site in 1992 and from the dry site and a wet site in 1993. Modulus of elasticity (e ), osmotic potential at...

Changes on sewage sludge stability after greenhouse drying

NASA Astrophysics Data System (ADS)

Soriano-Disla, J. M.; Houot, S.; Imhoff, M.; Valentin, N.; Gómez, I.; Navarro-Pedreño, J.

2009-04-01

The progressive implementation of the Urban Waste Water Treatment Directive 91/271/EEC in all the European member states is increasing the quantities of sewage sludge requiring disposal. Sludge application onto cultivated soils as organic fertilizers allows the recycling of nutrients. The application of only dehydrated sludges has generated many problems including unpleasant odours and difficult management (regarding transport and application) related to their high water content. One way to overcome these problems, in a cheap and clean way, is the drying of sludges using the energy of the sun under greenhouse conditions. This drying may affect sludge chemical characteristics including organic matter stability and nitrogen availability, parameters which have to be controlled for the proper management of dry sludge application onto soils. For this reason, the main aim of this work was to study the impact of greenhouse drying of different sewage sludges on their organic matter stability and nitrogen availability, assessed by biochemical fractionation and mineralization assays. Three sewage sludges were sampled before (dehydrated sludges) and after greenhouse drying (dried sludges). The analyses consisted of: humidity, organic matter, mineral and organic N contents, N and C mineralization during 91-day laboratory incubations in controlled conditions, and biochemical fractionation using the Van Soest procedure. Greenhouse drying decreased the water content from 70-80% to 10% and also the odours, both of which will improve the management of the final product from the perspective of application and transport. We also found that drying reduced the organic matter content of the sludges but not the biodegradability of the remaining carbon. Organic N mineralization occurred during greenhouse drying, explaining why mineral N content tended to increase and the potential mineralization of organic nitrogen decreased after greenhouse drying. The biochemical stability did not change so much except for the one of the sludges, which experienced an important reduction. According to the results, and from a point of view of future soil applications, the balance of the drying process could be considered as positive. It is using a free, renewable and clean energy, which reduces the water content and odours of sludge, thereby improving their management. Except for the water content, there was little modification of the behaviour in soil of greenhouse dried sludges compared to the dehydrated sludges, maintaining its large amount of available nitrogen after drying. Acknowledgements: Jose. M. Soriano-Disla gratefully acknowledges the Spanish Ministry of Innovation and Culture for a research fellowship (AP2005-0320).

Maize (Zea mays L.) performance in organically amended mine site soils.

PubMed

Oladipo, Oluwatosin Gbemisola; Olayinka, Akinyemi; Awotoye, Olusegun Olufemi

2016-10-01

Organic amendments play an important role in the eco-friendly remediation of degraded mine site soils. This study investigated the quality (essential nutrients and heavy metal content) of maize grown on organically amended soils from three active mines in Nigeria. Soil samples were collected randomly at 0-15 cm depth, air-dried and sieved. Five kg of soil were amended with poultry manure and sawdust (poultry manure only, sawdust only, poultry manure-sawdust mixtures in 3:1, 2:1 and 1:1 ratios) at 10 g kg(-1). Maize (Zea mays L.) seeds were planted and watered for two consecutive periods of 8 weeks, with the control and treatment experiments set up in the screenhouse in quadruples. Harvested tissues were weighed, dried, ground and digested. Chemical properties were determined using standard methods while atomic absorption spectrophotometry was used to determine total metal concentrations (Ca, Mg, Fe, Zn, Pb, Cd and Cu). ANOVA was used to test for significant differences among treatment groups in the various parameters. Application of poultry manure-sawdust mixtures significantly (p < 0.05) enhanced tissue dry matter yield, as well as N, P, K, and Na contents while Zn, Cd, Cu and Pb were immobilized to approximately 50-100%. Treatment with sawdust alone reduced tissue nutrient content resulting in depressed plant yield while poultry manure only though enhanced crop yield, contained higher heavy metal contents. Soil amendments comprised of poultry manure-sawdust mixtures can be effective remediation strategy for mine site soils, as these organic materials help replenish soil nutrients, immobilize heavy metals, and enhance food productivity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Arbuscular Mycorrhiza Alleviates Restrictions to Substrate Water Flow and Delays Transpiration Limitation to Stronger Drought in Tomato

PubMed Central

Bitterlich, Michael; Sandmann, Martin; Graefe, Jan

2018-01-01

Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic conductivity were rarely quantified. Hence, we asked whether inoculation with AMF affects substrate water retention, water transport properties and at which drought intensity those factors become limiting for plant transpiration. Solanum lycopersicum plants were set up in the glasshouse, inoculated or not with Funneliformis mosseae, and grown for 35 days under ample water supply. After mycorrhizal establishment, we harvested three sets of plants, one before (36 days after inoculation) and the second (day 42) and third (day 47) within a sequential drying episode. Sampling cores were introduced into pots before planting. After harvest, moisture retention and substrate conductivity properties were assessed and water retention and hydraulic conductivity models were fitted. A root water uptake model was adopted in order to identify the critical substrate moisture that induces soil derived transpiration limitation. Neither substrate porosity nor saturated water contents were affected by inoculation, but both declined after substrates dried. Drying also caused a decline in pot water capacity and hydraulic conductivity. Plant available water contents under wet (pF 1.8–4.2) and dry (pF 2.5–4.2) conditions increased in mycorrhizal substrates and were conserved after drying. Substrate hydraulic conductivity was higher in mycorrhizal pots before and during drought exposure. After withholding water from pots, higher substrate drying rates and lower substrate water potentials were found in mycorrhizal substrates. Mycorrhiza neither affected leaf area nor root weight or length. Consistently with higher substrate drying rates, AMF restored the plant hydraulic status, and increased plant transpiration when soil moisture declined. The water potential at the root surface and the resistance to water flow in the rhizosphere were restored in mycorrhizal pots although the bulk substrate dried more. Finally, substrates colonized by AMF can be more desiccated before substrate water flux quantitatively limits transpiration. This is most pronounced under high transpiration demands and complies with a difference of over 1,000 hPa in substrate water potential. PMID:29503655

Soil methane and CO2 fluxes in rainforest and rubber plantations

NASA Astrophysics Data System (ADS)

Lang, Rong; Blagodatsky, Sergey; Goldberg, Stefanie; Xu, Jianchu

2017-04-01

Expansion of rubber plantations in South-East Asia has been a land use transformation trend leading to losses of natural forest cover in the region. Besides impact on ecosystem carbon stocks, this conversion influences the dynamics of greenhouse gas fluxes from soil driven by microbial activity, which has been insufficiently studied. Aimed to understand how land use change affects the soil CO2 and CH4 fluxes, we measured surface gas fluxes, gas concentration gradient, and 13C signature in CH4 and soil organic matter in profiles in a transect in Xishuangbanna, including a rainforest site and three rubber plantation sites with age gradient. Gas fluxes were measured by static chamber method and open chamber respiration system. Soil gases were sampled from installed gas samplers at 5, 10, 30, and 75cm depth at representative time in dry and rainy season. The soil CO2 flux was comparable in rainforest and old rubber plantations, while young rubber plantation had the lowest rate. Total carbon content in the surface soil well explained the difference of soil CO2 flux between sites. All sites were CH4 sinks in dry season and uptake decreased in the order of rainforest, old rubber plantations and young rubber plantation. From dry season to rainy season, CH4 consumption decreased with increasing CH4 concentration in the soil profile at all depths. The enrichment of methane by 13CH4 shifted towards to lowerδ13C, being the evidence of enhanced CH4 production process while net surface methane flux reflected the consumption in wet condition. Increment of CH4 concentration in the profile from dry to rainy season was higher in old rubber plantation compared to rainforest, while the shifting of δ13CH4 was larger in rainforest than rubber sites. Turnover rates of soil CO2 and CH4 suggested that the 0-5 cm surface soil was the most active layer for gaseous carbon exchange. δ13C in soil organic matter and soil moisture increased from rainforest, young rubber plantation to old rubber plantations. Conversion the forest into rubber plantation decreased soil respiration in young plantation and it recovered during rubber development. However, the CH4consumption by tropical upland forest soil decreased in converted rubber plantations of all ages, with more decrement in old plantation. Change forest into rubber plantations weakened the soil function as CH4 sink.

NNSS Soils Monitoring: Plutonium Valley (CAU 366) FY2013 and FY2014

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Julianne J.; Nikolich, George; Mizell, Steve

The Desert Research Institute (DRI) is conducting a field assessment of the potential for contaminated soil transport from the Plutonium Valley Contamination Area (CA) as a result of wind transport and storm runoff in support of Nevada Nuclear Security Administration (NNSA) efforts to complete regulatory closure of the contamination areas. The DRI work is intended to confirm the likely mechanism(s) of transport and determine the meteorological conditions that might cause movement of contaminated soils. Emphasis is given to collecting sediment transported by channelized storm runoff at the Plutonium Valley investigation sites. These data will inform closure plans that are beingmore » developed, which will facilitate appropriate closure design and postclosure monitoring. Desert Research Institute installed two meteorological monitoring stations south (station number 1) and north (station number 2) of the Plutonium Valley CA and a runoff sediment sampling station within the CA in 2011. Temperature, wind speed, wind direction, relative humidity, precipitation, solar radiation, barometric pressure, soil temperature, and airborne particulate concentration are collected at both meteorological stations. The maximum, minimum, and average or total (as appropriate) for each of these parameters is recorded for each 10-minute interval. The sediment sampling station includes an automatically activated ISCO sampling pump with collection bottles for suspended sediment, which is activated when sufficient flow is present in the channel, and passive traps for bedload material that is transported down the channel during runoff events. This report presents data collected from these stations during FY2013 and FY2014.« less

Dry-heat resistance of selected psychrophiles. [Viking lander in spacecraft sterilization

NASA Technical Reports Server (NTRS)

Winans, L.; Pflug, I. J.; Foster, T. L.

1977-01-01

The dry-heat resistance characteristics of spores of psychrophilic organisms isolated from soil samples from the Viking spacecraft assembly areas at Cape Kennedy Space Flight Center, Cape Canaveral, Fla., were studied. Spore suspensions were produced, and dry-heat D values were determined for the microorganisms that demonstrated growth or survival under a simulated Martian environment. The dry-heat tests were carried out by using the planchet-boat-hot plate system at 110 and 125 C with an ambient relative humidity of 50% at 22 C. The spores evaluated had a relatively low resistance to dry heat. D (110 C) values ranged from 7.5 to 122 min, whereas the D (125 C) values ranged from less than 1.0 to 9.8 min.

Dry-heat resistance of selected psychrophiles.

PubMed Central

Winans, L; Pflug, I J; Foster, T L

1977-01-01

The dry-heat resistance characteristics of spores of psychrophilic organisms isolated from soil samples from the Viking spacecraft assembly areas at Cape Kennedy Space Flight Center, Cape Canaveral, Fla., were studied. Spore suspensions were produced, and dry-heat D values were determined for the microorganisms that demonstrated growth or survival under a simulated Martian environment. The dry-heat tests were carried out by using the planchet-boat-hot plate system at 110 and 125 degrees C with an ambient relative humidity of 50% at 22 degrees C. The spores evaluated had a relatively low resistance to dry heat. D(110 degrees C) values ranged from 7.5 to 122 min, whereas the D(123 degrees C) values ranged from less than 1.0 to 9.8 min. PMID:410367

DNA analysis of soil extracts can be used to investigate fine root depth distribution of trees

PubMed Central

Bithell, Sean L.; Tran-Nguyen, Lucy T. T.; Hearnden, Mark N.; Hartley, Diana M.

2015-01-01

Understanding the root distribution of trees by soil coring is time-consuming as it requires the separation of roots from soil and classification of roots into particular size classes. This labour-intensive process can limit sample throughput and therefore sampling intensity. We investigated the use of quantitative polymerase chain reaction (qPCR) on soil DNA extractions to determine live fine root DNA density (RDD, mg DNA m−2) for mango (Mangifera indica) trees. The specificity of the qPCR was tested against DNA extracted from 10 mango cultivars and 14 weed species. All mango cultivars and no weeds were detected. Mango DNA was successfully quantified from control soil spiked with mango roots and weed species. The DNA yield of mango root sections stored in moist soil at 23–28 °C declined after 15 days to low concentrations as roots decayed, indicating that dead root materials in moist soil would not cause false-positive results. To separate large roots from samples, a root separation method for field samples was used to target the root fragments remaining in sieved (minimum 2 mm aperture) soil for RDD comparisons. Using this method we compared the seasonal RDD values of fine roots for five mango rootstock cultivars in a field trial. The mean cultivar DNA yields by depth from root fragments in the sieved soil samples had the strongest relationship (adjusted multiple R2 = 0.9307, P < 0.001) with the dry matter (g m−2) of fine (diameter <0.64 mm) roots removed from the soil by sieving. This method provides a species-specific and rapid means of comparing the distribution and concentration of live fine roots of trees in orchards using soil samples up to 500 g. PMID:25552675

Contaminants in landfill soils - Reliability of prefeasibility studies.

PubMed

Hölzle, Ingo

2017-05-01

Recent landfill mining studies have researched the potential for resource recovery using samples from core drilling or grab cranes. However, most studies used small sample numbers, which may not represent the heterogeneous landfill composition. As a consequence, there exists a high risk of an incorrect economic and/or ecological evaluation. The main objective of this work is to investigate the possibilities and limitations of preliminary investigations concerning the crucial soil composition. The preliminary samples of landfill investigations were compared to the excavation samples from three completely excavated landfills in Germany. In addition, the research compared the reliability of prediction of the two investigation methods, core drilling and grab crane. Sampling using a grab crane led to better results, even for smaller investigations of 10 samples. Analyses of both methods showed sufficiently accurate results to make predictions (standard error 5%, level of confidence 95%) for most heavy metals, cyanide and PAH in the dry substance and for sulphate, barium, Benzo[a]pyrene, pH and the electrical conductivity in leachate analyses of soil type waste. While chrome and nickel showed less accurate results, the concentrations of hydrocarbons, TOC, DOC, PCB and fluorine (leachate) were not predictable even for sample numbers of up to 59. Overestimations of pollutant concentrations were more frequently apparent in drilling, and underestimations when using a grab crane. The dispersion of the element and elemental composition had no direct impact on the reliability of prediction. Thus, an individual consideration of the particular element or elemental composition for dry substance and leachate analyses is recommended to adapt the sample strategy and calculate an optimum sample number. Copyright © 2016 Elsevier Ltd. All rights reserved.

4,4'-DDE and Endosulfan Levels in Agricultural Soils of the Çukurova Region, Mediterranean Turkey.

PubMed

Akça, Muhittin Onur; Hisatomi, Shihoko; Takemura, Manami; Harada, Naoki; Nonaka, Masanori; Sakakibara, Futa; Takagi, Kazuhiro; Turgay, Oğuz Can

2016-03-01

Mediterranean Turkey has long been at the forefront of Turkish agriculture and the use of organochlorinated pesticides (OCPs) in this area rose considerably between the 1940s and 1980s. This study aimed to determine OCP residue levels in agricultural soils collected from the Mersin and Adana Districts, Çukurova Basin in Mediterranean Turkey. Most soil samples were contaminated with one, or both, of two OCP metabolites; 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE) and endosulfan sulfate. 4,4'-DDE occurred in 27 of the 29 samples and ranged from 6 to 1090 µg kg(-1)-dry soil (ds)(-1), while six samples contained endosulfan sulfate ranging between 82 and 1226 µg kg(-1)-ds(-1). Generally, horticultural and corn-planted soils contained only 4,4'-DDE, whereas greenhouse cultivation appeared to accumulate both residues. This study indicated that 4,4'-DDE occurred above acceptable levels of risk in agricultural soils of Mersin District and further studies on the qualitative and quantitative assessment of OCPs in other agricultural regions with intensive pesticide use are necessary to fully understand the impact of OCPs on agricultural soil in Turkey.

NH4NO3 extractable trace element contents of soil samples prepared for proficiency testing--a stability study.

PubMed

Traub, H; Scharf, H

2001-06-01

In view of its intended use as a sample for proficiency testing or as a reference material the stability of the extractable trace element contents of a soil from an irrigation field was tested using the extraction with 1 mol/L ammonium nitrate solution according to DIN 19730. Therefore, changes of the extractability of sterilized and non sterilized soil samples stored at different temperatures were evaluated over a period of 18 months. Sets of bottles were kept at -20 degrees C, +4 degrees C, about +20 degrees C and +40 degrees C, respectively. The NH4NO3 extractable contents of Cd, Cr, Cu, Ni, Pb and Zn were determined immediately after bottling and then after 3, 6, 12 and 18 months with ICP-AES or ETAAS. Appropriate storage conditions are of utmost importance to prevent deterioration of soil samples prepared for the determination of NH4NO3 extractable trace element contents. Temperatures above +20 degrees C must be avoided. The observed changes in the extractability of the metals (especially for Cr and Cu) most likely could be related to thermal degradation of the organic matter of the soil. There is no need to sterilize dry soil samples, because microbiological activity in soils with a low moisture content appears to be negligible with regard to trace element mobilization.

Soil organic matter degradability in four Japanese forest soils

NASA Astrophysics Data System (ADS)

Moriya, K.; Koarashi, J.; Atarashi-Andoh, M.; Moriizumi, J.; Yamazawa, H.; Ishizuka, S.

2011-12-01

Soil organic carbon (SOC) is the largest carbon reservoir in terrestrial ecosystems, and CO2 emission derived from SOC decomposition is considered to strongly influence atmospheric CO2 concentration. Therefore, it is important to understand what factors control the process of SOC decomposition. We studied the temperature sensitivity of SOC decomposition in forest surface soils by an incubation experiment at two temperatures. Soil samples were collected from the top 20 cm of mineral soils at four forest sites in Japan: AP (Appi: 40°00'N, 140°56'E), US (Ushiku: 35°57'N, 140°10'E), OG (Ogawa: 36°56'N, 140°35'E), and HO (Hitsujigaoka: 43°59'N, 141°23'E). The soil samples were sieved with a 4 mm-mesh and remaining roots in the samples were carefully removed by hand. Approximately a 75 g dry weight equivalent of the sample was adjusted to 50% of water holding capacity and put into a 1 L jar. Triplicate jars were enclosed after flushing their headspaces with CO2-free air and incubated at temperatures of 10°C and 20°C, respectively. We periodically collected 1 mL of headspace gas from the jars to measure CO2 concentration using a gas chromatograph. When the CO2 concentration in each jar reached 1.5% in volume, the headspace gas in the jar was collected to measure carbon isotope ratio of the CO2, and then the headspace of the jar was re-flushed and continued to incubate. The SOC decomposition rate at 20°C was consistently higher than that at 10°C, the order of which was AP ≤ US ≤ OG < HO. This order did not correspond to the orders of both mean annual temperature at the sites (AP < HO < OG < US), and total organic carbon content per dry soil weight (HO < US < AP < OG). Our result suggests that field temperature does not exert predominant control over SOC degradability in Japanese forest surface soils. Q10 values obtained for the AP, US, and OG soils was initially approximately 3 and increased up to 4 after one month of incubation. The increase in Q10 value was possibly due to reducing in labile SOC. Our result support that recalcitrant substrates with the higher activation energy are more sensitive to temperature than labile ones.

The Evaluation of Basal Respiration for Various Soil Textures in Ecologically Sensitive Area

NASA Astrophysics Data System (ADS)

Huličová, P.; Kotorová, D.; Fazekašová, D.; Hynšt, J.

2017-10-01

The present contribution was focused on monitoring changes in the soil basal respiration in different textures of soil in the dry polder Beša. The research was conducted between 2012 and 2014 on soil type Fluvisol locations on three soil textures: clay - loam soil, clayey soil and clay soil in three soil depths. The basal respiration (BR) has been determine by soil CO2 production measuring from incubated soil samples in serum bottles in laboratory condition. Release Co2 has been analysed by gas chromatography. Content of clay particles were in the range 52.18 % to 81.31%, indicating the high difference between the minimum and maximum content. By using of multiple LSD-test we recorded statistically significant impact of clay on basal respiration. Results confirm the values of basal respiration with the depth of the soil profile decreased.

Life at extreme elevations on Atacama volcanoes: the closest thing to Mars on Earth?

PubMed

Schmidt, S K; Gendron, E M S; Vincent, K; Solon, A J; Sommers, P; Schubert, Z R; Vimercati, L; Porazinska, D L; Darcy, J L; Sowell, P

2018-03-20

Here we describe recent breakthroughs in our understanding of microbial life in dry volcanic tephra ("soil") that covers much of the surface area of the highest elevation volcanoes on Earth. Dry tephra above 6000 m.a.s.l. is perhaps the best Earth analog for the surface of Mars because these "soils" are acidic, extremely oligotrophic, exposed to a thin atmosphere, high UV fluxes, and extreme temperature fluctuations across the freezing point. The simple microbial communities found in these extreme sites have among the lowest alpha diversity of any known earthly ecosystem and contain bacteria and eukaryotes that are uniquely adapted to these extreme conditions. The most abundant eukaryotic organism across the highest elevation sites is a Naganishia species that is metabolically versatile, can withstand high levels of UV radiation and can grow at sub-zero temperatures, and during extreme diurnal freeze-thaw cycles (e.g. - 10 to + 30 °C). The most abundant bacterial phylotype at the highest dry sites sampled (6330 m.a.s.l. on Volcán Llullaillaco) belongs to the enigmatic B12-WMSP1 clade which is related to the Ktedonobacter/Thermosporothrix clade that includes versatile organisms with the largest known bacterial genomes. Close relatives of B12-WMSP1 are also found in fumarolic soils on Volcán Socompa and in oligotrophic, fumarolic caves on Mt. Erebus in Antarctica. In contrast to the extremely low diversity of dry tephra, fumaroles found at over 6000 m.a.s.l. on Volcán Socompa support very diverse microbial communities with alpha diversity levels rivalling those of low elevation temperate soils. Overall, the high-elevation biome of the Atacama region provides perhaps the best "natural experiment" in which to study microbial life in both its most extreme setting (dry tephra) and in one of its least extreme settings (fumarolic soils).

Dry particle generation with a 3-D printed fluidized bed generator

DOE PAGES

Roesch, Michael; Roesch, Carolin; Cziczo, Daniel J.

2017-06-02

We describe the design and testing of PRIZE (PRinted fluidIZed bed gEnerator), a compact fluidized bed aerosol generator manufactured using stereolithography (SLA) printing. Dispersing small quantities of powdered materials – due to either rarity or expense – is challenging due to a lack of small, low-cost dry aerosol generators. With this as motivation, we designed and built a generator that uses a mineral dust or other dry powder sample mixed with bronze beads that sit atop a porous screen. A particle-free airflow is introduced, dispersing the sample as airborne particles. The total particle number concentrations and size distributions were measured duringmore » different stages of the assembling process to show that the SLA 3-D printed generator did not generate particles until the mineral dust sample was introduced. Furthermore, time-series measurements with Arizona Test Dust (ATD) showed stable total particle number concentrations of 10–150 cm -3, depending on the sample mass, from the sub- to super-micrometer size range. Additional tests with collected soil dust samples are also presented. PRIZE is simple to assemble, easy to clean, inexpensive and deployable for laboratory and field studies that require dry particle generation.« less

Dry particle generation with a 3-D printed fluidized bed generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roesch, Michael; Roesch, Carolin; Cziczo, Daniel J.

We describe the design and testing of PRIZE (PRinted fluidIZed bed gEnerator), a compact fluidized bed aerosol generator manufactured using stereolithography (SLA) printing. Dispersing small quantities of powdered materials – due to either rarity or expense – is challenging due to a lack of small, low-cost dry aerosol generators. With this as motivation, we designed and built a generator that uses a mineral dust or other dry powder sample mixed with bronze beads that sit atop a porous screen. A particle-free airflow is introduced, dispersing the sample as airborne particles. The total particle number concentrations and size distributions were measured duringmore » different stages of the assembling process to show that the SLA 3-D printed generator did not generate particles until the mineral dust sample was introduced. Furthermore, time-series measurements with Arizona Test Dust (ATD) showed stable total particle number concentrations of 10–150 cm -3, depending on the sample mass, from the sub- to super-micrometer size range. Additional tests with collected soil dust samples are also presented. PRIZE is simple to assemble, easy to clean, inexpensive and deployable for laboratory and field studies that require dry particle generation.« less

Weathering and genesis of Soils from Ellsworth Mountains, East Antarctica

NASA Astrophysics Data System (ADS)

Karoline Delpupo Souza, Katia; Schaefer, Carlos Ernesto; Michel, Roberto; Monari, Julia; Machado, Vania

2015-04-01

Knowledge on Antarctic soils from the Ellsworth Mountains (EM) are patchy comparatively with Dry Valleys soils from the Transantartic Mountains, and could help understand the genesis of cryogenic soils under extreme dry, cold desert conditions. The EM are a slightly arcuate 350-km-long north-northwest-trending mountain chain is bordered on the west by the polar plateau of West Antarctica and on the east by Ronne Ice Shelf. The range is as much as 90 km wide and constitutes one of the largest areas of exposed bedrock in West Antarctica. The stratigraphic succession in the EM includes strata from Cambriam to Permian in age. The objective of this study is to analyze the properties of soils from EM in order to identify the main factors and processes involved in soil formation under cold desert conditions in Antarctica. The sampling design aimed to represent the different geological substrates (marble-clast conglomerate, graywacke, argillite, conglomerate, black shale, marble and quartzite) as well as altitudinal levels and landforms within the same substrate. We characterized soils from EM regarding their morphological, physics and chemical properties. Soil samples were air dried and passed through 2 mm sieves. After removal of water soluble salts, the samples were submitted to chemical and physical analyses such as: pH in water, potential acidity (H + Al), exchangeable bases, total organic carbon, electric conductivity, soil texture and color. The soils classify, for the most part, in weathering stages 1 to 2. Only in the upper parts of ridges were there traces of soils at weathering stage 3. This indicates that much of the present icefree topography has been overridden by ice within the last few hundred thousand years. Cryoturbation is a widespread phenomenon in this area resulting in intense cryoclastic weathering and patterned ground, forming sorted circles, stripes and gelifluxion lobes. The soil show low horizontation, discrete patches of salt on the surface, and salt crusts beneath the rock fragments. Despite of the low weathering stage of the soil, they have yellowish hue and high chroma values from influence by sulfide material. Boulders on moraines show staining, pitting, spalling, and some striations. All soil are alkaline in reaction, with pHs at the range between 7.5-9.2. Cryptogamic (lichens or mosses) crusts are absent, and the organic matter contents were invariably very low, ranging between 0.13 and 0.38%. Permafrost is continuous and occurs close to the surface, at between 5-15 cm down the top. The available P background is also very low (< 5.3 mg/kg), exchangeable K and Na levels are surprisingly low for Polar Desert soils. Soils are all skelletic, with a predominance of coarse materials. CEC is medium to high, and Ca-dominated, as a result of a strong limestone influence in the moraine parent materials. The main salts present are Ca and Na-sulphate forms, and less cloride forms, and clay sized materials are dominated by salts in all soils, especially below 5 cm depth.

Growth and transpiration of Japanese cedar (Cryptomeria japonica) and Hinoki cypress (Chamaecyparis obtusa) seedlings in response to soil water content.

PubMed

Nagakura, Junko; Shigenaga, Hidetoshi; Akama, Akio; Takahashi, Masamichi

2004-11-01

To investigate the effects of soil water content on growth and transpiration of Japanese cedar (Cryptomeria japonica D. Don) and Hinoki cypress (Chamaecyparis obtusa (Siebold et Zucc.) Endl.), potted seedlings were grown in well-watered soil (wet treatment) or in drying soil (dry treatment) for 12 weeks. Seedlings in the wet treatment were watered once every 2 or 3 days, whereas seedlings in the dry treatment were watered when soil water content (Theta; m3 m(-3)) reached 0.30, equivalent to a soil matric potential of -0.06 MPa. From Weeks 7 to 12 after the onset of the treatments, seedling transpiration was measured by weighing the potted seedlings. After the last watering, changes in transpiration rate during soil drying were monitored intensely. The dry treatment restricted aboveground growth but increased biomass allocation to the roots in both species, resulting in no significant treatment difference in whole-plant biomass production. The species showed similar responses in relative growth rate (RGR), net assimilation rate (NAR) and shoot mass ratio (SMR) to the dry treatment. Although NAR did not change significantly in either C. japonica or C. obtusa as the soil dried, the two species responded differently to the dry treatment in terms of mean transpiration rate (E) and water-use efficiency (WUE), which are parameters that relate to NAR. In the dry treatment, both E and WUE of C. japonica were stable, whereas in C. obtusa, E decreased and WUE increased (E and WUE counterbalanced to maintain a constant NAR). Transpiration rates were lower in C. obtusa seedlings than in C. japonica seedlings, even in well-watered conditions. During soil drying, the transpiration rate decreased after Theta reached about 0.38 (-0.003 MPa) in C. obtusa and 0.32 (-0.028 MPa) in C. japonica. We conclude that C. obtusa has more water-saving characteristics than C. japonica, particularly when water supply is limited.

Studies on mycorrhizal inoculation on dry matter yield and root colonization of some medicinal plants grown in stress and forest soils.

PubMed

Chandra, K K; Kumar, Neeraj; Chand, Gireesh

2010-11-01

Five medicinal plants viz. Abelmoschatus moschatus Linn., Clitoria tematea L., Plumbagozeylanica L., Psorolea corylifolia L. and Withania sominifera L. were grown in a polypot experiment in five soils representing coal mine soil, coppermine soil, fly ash, skeletal soil and forest soil with and without mycorrhizal inoculations in a completely randomized block design. Dry matter yield and mycorrhizal root colonization of plants varied both in uninoculated and inoculated conditions. The forest soil rendered highest dry matter due to higher yield of A. moschatus, P. zeylanica and P corylifolia while fly ash showed lowest dry matter without any inoculants. P. cematea were best in coalmine soil and W. sominifera in copper mine soil without mycorrhizal inoculation. The mycorrhiza was found to enhance the dry matter yield. This contributed minimum 0.19% to maximum up to 422.0% in different soils as compared to uninoculated plants. The mycorrhizal dependency was noticed maximum in plants grown in fly ash followed by coal mine soil, copper mine soil, skeletal soil and forest soil. The mycorrhizal response was increased maximum in W. sominifera due to survival in fly ash after inoculation followed by P corylifolia and P cematea. Percent root colonization in inoculated plant was increased minimum of 1.10 fold to maximum of 12.0 folds in comparison to un-inoculated plants . The native mycorrhiza fungi were also observed to colonize 4.0 to 32.0% roots in plants understudy. This study suggests that mycorrhizal inoculation increased the dry matter yield of medicinal plants in all soils under study. It also helps in survival of W. sominifera in fly ash.

Ambient stable quantitative PCR reagents for the detection of Yersinia pestis.

PubMed

Qu, Shi; Shi, Qinghai; Zhou, Lei; Guo, Zhaobiao; Zhou, Dongsheng; Zhai, Junhui; Yang, Ruifu

2010-03-09

Although assays for detecting Yersinia pestis using TaqMan probe-based real-time PCR have been developed for years, little is reported on room-temperature-stable PCR reagents, which will be invaluable for field epidemic surveillance, immediate response to public health emergencies, counter-bioterrorism investigation, etc. In this work, a set of real-time PCR reagents for rapid detection of Y. pestis was developed with extraordinary stability at 37 degrees C. TaqMan-based real-time PCR assays were developed using the primers and probes targeting the 3a sequence in the chromosome and the F1 antigen gene caf1 in the plasmid pMT1of Y. pestis, respectively. Then, carbohydrate mixtures were added to the PCR reagents, which were later vacuum-dried for stability evaluation. The vacuum-dried reagents were stable at 37 degrees C for at least 49 days for a lower concentration of template DNA (10 copies/microl), and up to 79 days for higher concentrations (> or =10(2) copies/microl). The reagents were used subsequently to detect soil samples spiked with Y. pestis vaccine strain EV76, and 5x10(4) CFU per gram of soil could be detected by both 3a- and caf1-based PCR reagents. In addition, a simple and efficient method for soil sample processing is presented here. The vacuum-dried reagents for real-time PCR maintain accuracy and reproducibility for at least 49 days at 37 degrees C, indicating that they can be easily transported at room temperature for field application if the machine for performing real-time PCR is available. This dry reagent is of great significance for routine plague surveillance.

Ambient Stable Quantitative PCR Reagents for the Detection of Yersinia pestis

PubMed Central

Zhou, Lei; Guo, Zhaobiao; Zhou, Dongsheng; Zhai, Junhui; Yang, Ruifu

2010-01-01

Background Although assays for detecting Yersinia pestis using TaqMan probe-based real-time PCR have been developed for years, little is reported on room-temperature-stable PCR reagents, which will be invaluable for field epidemic surveillance, immediate response to public health emergencies, counter-bioterrorism investigation, etc. In this work, a set of real-time PCR reagents for rapid detection of Y. pestis was developed with extraordinary stability at 37°C. Methods/Principal Findings TaqMan-based real-time PCR assays were developed using the primers and probes targeting the 3a sequence in the chromosome and the F1 antigen gene caf1 in the plasmid pMT1of Y. pestis, respectively. Then, carbohydrate mixtures were added to the PCR reagents, which were later vacuum-dried for stability evaluation. The vacuum-dried reagents were stable at 37°C for at least 49 days for a lower concentration of template DNA (10 copies/µl), and up to 79 days for higher concentrations (≥102 copies/µl). The reagents were used subsequently to detect soil samples spiked with Y. pestis vaccine strain EV76, and 5×104 CFU per gram of soil could be detected by both 3a- and caf1-based PCR reagents. In addition, a simple and efficient method for soil sample processing is presented here. Conclusions/Significance The vacuum-dried reagents for real-time PCR maintain accuracy and reproducibility for at least 49 days at 37°C, indicating that they can be easily transported at room temperature for field application if the machine for performing real-time PCR is available. This dry reagent is of great significance for routine plague surveillance. PMID:20231881

[Determination of trace metals in atmospheric dry deposition with a heavy matrix of PUF by inductively coupled plasma mass spectroscopy after microwave digestion].

PubMed

Pan, Yue-peng; Wang, Yue-si; Yang, Yong-jie; Wu, Dan; Xin, Jin-yuan; Fan, Wen-yan

2010-03-01

Interest in atmospheric dry deposition results mostly from concerns about the effects of the deposited trace elements entering waterbody, soil and vegetation as well as their subsequent health effects. A microwave assisted digestion method followed by inductively coupled plasma mass spectrometric (MAD-ICP/MS) analysis was developed to determine the concentrations of a large number of trace metals in atmospheric dry deposition samples with a heavy matrix of polyurethane foam (PUF). A combination of HNO3-H2O2-HF was used for digestion. The experimental protocol for the microwave assisted digestion was established using two different SRMs (GBW 07401, Soil and GBW 08401, Coal fly ash). Subsequently, blanks and limits of detection for total trace metal concentrations were determined for PUF filter which was used for dry deposition sampling. Finally, the optimized digestion method was applied to real world atmospheric dry deposition samples collected at 10 sites in Jingjinji area in winter from Dec. 2007 to Feb. 2008. The results showed that the area-averaged total mass fluxes ranged between 85 and 912 mg x (m2 x d)(-1), and fluxes of most elements were highest at Baoding and lowest at Xinglong. In addition, the elemental fluxes in urban areas of Beijing, Tianjin and Tangshan were measured to be higher than that in suburb and rural sites. The average fluxes of crust elements (A1, Fe, Mn, K, Na, Ca and Mg) were one to three orders of magnitude higher than anthropogenic elements (Cu, Pb, Cr, Ni, V, Zn and Ba), varying from 151 to 16034 microg x (m2 x d)(-1) versus 14 to 243 microg x (m2 x d)(-1). Zinc was the most abundant heavy metal and calcium the highest of the crust elements while the elements Mo, Co, Cd, As and Be deposited less or even could not be detected. The anthropogenic and crustal contributions were estimated by employing enrichment factors (EF) calculated relative to the average crustal composition. The EF values of all elements except Pb and Zn were below 10, suggesting that local soil and/or dust generally dominate in the dry deposition flux.

An assessment of soil-to-plant concentration ratios for some natural analogues of the transuranic elements.

PubMed

Linsalata, P; Morse, R S; Ford, H; Eisenbud, M; Franca, E P; de Castro, M B; Lobao, N; Sachett, I; Carlos, M

1989-01-01

A field study was conducted in an area of enhanced, natural radioactivity to assess the soil to edible vegetable concentration ratios (CR = concentration in dry vegetable/concentration in dry soil) of 232Th, 230Th, 226Ra, 228Ra, and the light rare earth elements (REE's) La, Ce and Nd. Twenty-nine soil and 42 vegetable samples consisting of relatively equal numbers of seven varieties were obtained from 11 farms on the Pocos de Caldas Plateau in the state of Minas Gerais, Brazil. This region is the site of a major natural analogue study to assess the mobilization and retardation processes affecting Th and the REE's at the Morro do Ferro ore body and U series radionuclides at a nearby open pit U mine. Thorium (IV) serves as a chemical analogue for quadrivalent Pu and the light REE's (III) as chemical analogues for trivalent Am and Cm. The geometric mean CR's (all times 10(-4] decreased as 228Ra (148) greater than 226Ra (76) greater than La (5.4) greater than Nd (3.0) = Ce (2.6) greater than 232Th (0.6), or simply as M (II) greater than M (III) greater than M (IV). These differences may reflect the relative availability of these metals for plant uptake. Significant differences were found in the CR's (for any given analyte) among many of the vegetables sampled. The CR's for the different analytes were also highly correlated. The reasons for the correlations in CR's seen among elements with such diverse chemistries as Ra-REE or Ra-Th are not clear but are apparently related to the essential mineral requirements or mineral status of the different vegetables sampled. This conclusion is based on the significant correlations obtained between the Ca content of the dried vegetables and the CR's for all of the elements studied.

Associations between soil variables and vegetation structure and composition of Caribbean dry forests

Treesearch

Elvia M. Melendez-Ackerman; Julissa Rojas-Sandoval; Danny S. Fernandez; Grizelle Gonzalez; Hana Lopez; Jose Sustache; Mariely Morales; Miguel Garcia-Bermudez; Susan Aragon

2016-01-01

Soil–vegetation associations have been understudied in tropical dry forests when compared to the amount of extant research on this issue in tropical wet forests. Recent studies assert that vegetation in tropical dry forests is highly heterogeneous and that soil variability may be a contributing factor. In this study, we evaluated the relationship between soil variables...

Development of a mobile system based on laser-induced breakdown spectroscopy and dedicated to in situ analysis of polluted soils

NASA Astrophysics Data System (ADS)

Bousquet, B.; Travaillé, G.; Ismaël, A.; Canioni, L.; Michel-Le Pierrès, K.; Brasseur, E.; Roy, S.; le Hecho, I.; Larregieu, M.; Tellier, S.; Potin-Gautier, M.; Boriachon, T.; Wazen, P.; Diard, A.; Belbèze, S.

2008-10-01

Principal Components Analysis (PCA) is successfully applied to the full laser-induced breakdown spectroscopy (LIBS) spectra of soil samples, defining classes according to the concentrations of the major elements. The large variability of the LIBS data is related to the heterogeneity of the samples and the representativeness of the data is finally discussed. Then, the development of a mobile LIBS system dedicated to the in-situ analysis of soils polluted by heavy metals is described. Based on the use of ten-meter long optical fibers, the mobile system allows deported measurements. Finally, the laser-assisted drying process studied by the use of a customized laser has not been retained to overcome the problem of moisture.

Interpolated mapping and investigation of environmental radioactivity levels in soils and mushrooms in the Middle Black Sea Region of Turkey.

PubMed

Türkekul, İbrahim; Yeşilkanat, Cafer Mert; Ciriş, Ali; Kölemen, Uğur; Çevik, Uğur

2018-06-01

The activity concentration of natural ( 238 U, 232 Th, and 40 K) and artificial ( 137 Cs) radionuclides was determined in 50 samples (obtained from the same station) from various species of mushrooms and soil collected from the Middle Black Sea Region (Turkey). The activities of 238 U, 232 Th, 40 K, and 137 Cs were found as 84 ± 16, 45 ± 14, 570 ± 28, and 64 ± 6 Bq kg -1 (dry weight), respectively, in the mushroom samples and as 51 ± 6, 41 ± 6, 201 ± 11, and 44 ± 4 Bq kg -1 , respectively, in the soil samples for the entire area of study. The results of all radionuclide activity measurements, except those of 238 U and 232 Th in the mushroom samples, are consistent with previous studies. In the soil samples, the mean values of 238 U and 232 Th are above the world mean, and the activity mean of 40 K is below the world mean. Finally, the activity estimation was made with both the soil and mushroom samples for unmeasured points within the study area by using the ordinary kriging method. Radiological distribution maps were generated.

Investigation of soil properties for identifying recharge characteristics in the Lake Chad Basin

NASA Astrophysics Data System (ADS)

Banks, M. L.; Ndunguru, G. G.; Adisa, S. J.; Lee, J.; Adegoke, J. O.; Goni, I. B.; Grindley, J.; Mulugeta, V.

2009-12-01

Lake Chad was once labeled as one of the largest fresh water lakes in the world, providing water and livelihood to over 20 million people. The lake is shared by six different countries; Chad Nigeria, Niger, Cameroon, Central African Republic, and Sudan. Since the 1970 to date, a significant decrease in the size of the lake has been observed with the use of satellite imagery. This shrinking of the lake has been blamed on global warming, population increase and poor water management by the agriculture industry for farming purpose for both plants and animals. While these can be all valid reasons for the decrease of Lake Chad, we see the need to examine environmental and hydrological evidence around the Lake Chad basin. This study was carried out from upper stream to lower stream leading from Kano to the Damatru region which is one of several water bodies that supply Lake Chad. Over seventy six sites were sampled for soil texture, bulk density and other physical properties to investigate recharge capacity of the basin especially along the stream. Soils were collected using a soil core and properly stored at 4 degrees Celsius. Soils were weighed and put to dry at 105 degrees for twenty four hours. Dry weight was recorded and bulk density was calculated. The wet sieve method was used to determine the particle size analysis. Soils were weighed to 10 grams and hydrogen peroxide added to separate particles. Samples were washed with water and put to dry overnight. Soils were reweighed and sieved to separate as course sand, fine sand and silt and clay. The data revealed that in the upstream, coarse sand continuously decreased while silt and clay continuously increased down toward the lake. At mid stream silt and clay had significantly higher values when compared to coarse sand and fine sand. In the lower stream, bulk density clearly decreased compared to the upper and mid streams. Correlations will be carried out to investigate the particle size analysis and bulk density with recharge capacity of the lake Chad Basin.

Dissolved carbon and nitrogen dynamics in paddy fields under different water management practices and implications on green-house gas emissions

NASA Astrophysics Data System (ADS)

Miniotti, Eleonora; Said-Pullicino, Daniel; Bertora, Chiara; Pelissetti, Simone; Sacco, Dario; Grignani, Carlo; Lerda, Cristina; Romani, Marco; Celi, Luisella

2013-04-01

The alternation of oxidizing and reducing conditions in paddy soils results in considerable complexity in the biogeochemical cycling of elements and their interactions, influencing important soil processes. Water management practices may play an important role in controlling the loss of nutrients from rice paddies to surface and subsurface waters, as well as soil organic matter (SOM) stabilization and the emission of green-house gases (GHG) such as methane and nitrous oxide. The aim of this study was therefore to evaluate the interaction between changes in soil redox conditions and element cycling in temperate paddy soils as a function of different water management practices. The research was carried out within an experimental platform (1.2 ha) located at the Rice Research Center of Ente Nazionale Risi (Castello d'Agogna, PV, NW Italy) where three water management practices are being compared with two plots for each treatment. These included (i) rice cultivation under traditional submerged conditions (FLD); (ii) seeding under dry soil conditions and flooding delayed by about 40 days (DRY); (iii) seeding under dry soil conditions and rotational irrigation (IRR). Surface and subsurface (25, 50 and 75 cm) water samples were collected at regular intervals over the cropping season from V-notch weirs and porous ceramic suction cups installed in each plot, and subsequently analyzed for DOC, SUVA, Fe(II), ammonium and nitrate-N. Moreover, methane and nitrous oxide fluxes were measured in situ by the closed-chamber technique. DOC concentrations in soil solutions were generally higher in FLD and DRY treatments with respect to IRR throughout the cropping season. Higher DOC contents after field flooding in FLD and DRY treatments also corresponded with greater concentrations of reduced Fe, higher SUVA values, lower Eh values and higher pH values, suggesting that desorption of more aromatic, mineral-associated SOM could be responsible for the observed increase in DOC. These trends were not observed in the IRR treatment. The differences in DOC contents and in Eh trend between treatments could possibly explain the increasing trend in cumulative methane emissions in the order IRR<

Trace element analysis of soil type collected from the Manjung and central Perak

NASA Astrophysics Data System (ADS)

Azman, Muhammad Azfar; Hamzah, Suhaimi; Rahman, Shamsiah Abdul; Elias, Md Suhaimi; Abdullah, Nazaratul Ashifa; Hashim, Azian; Shukor, Shakirah Abd; Kamaruddin, Ahmad Hasnulhadi Che

2015-04-01

Trace elements in soils primarily originated from their parent materials. Parents' material is the underlying geological material that has been undergone different types of chemical weathering and leaching processes. Soil trace elements concentrations may be increases as a result of continuous input from various human activities, including power generation, agriculture, mining and manufacturing. This paper describes the Neutron Activation Analysis (NAA) method used for the determination of trace elements concentrations in part per million (ppm) present in the terrestrial environment soil in Perak. The data may indicate any contamination of trace elements contributed from human activities in the area. The enrichment factors were used to check if there any contamination due to the human activities (power plants, agricultural, mining, etc.) otherwise the values would serve as a baseline data for future study. The samples were collected from 27 locations of different soil series in the area at two different depths: the top soil (0-15cm) and the sub soil (15-30cm). The collected soil samples were air dried at 60°C and passed through 2 µm sieve. Instrumental Neutron Activation Analysis (NAA) has been used for the determination of trace elements. Samples were activated in the Nuclear Malaysia TRIGA Mark II reactor followed by gamma spectrometric analysis. By activating the stable elements in the samples, the elements can be determined from the intensities of gamma energies emitted by the respected radionuclides.

Impact of potato cultivation and cattle farming on physicochemical parameters and enzymatic activities of Neotropical high Andean Páramo ecosystem soils.

PubMed

Avellaneda-Torres, Lizeth Manuela; León Sicard, Tomás Enrique; Torres Rojas, Esperanza

2018-08-01

The Andean Páramos are high mountain ecosystems whose soils are essential for the management of South American water resources, but research on anthropic impacts to these soils is currently minimal and insufficient. The objective of this study was to evaluate the impacts of potato (Solanum tuberosum) cultivation and livestock on the physicochemical parameters and enzymatic activities that determine the soil quality of the Neotropical high Andean Páramo ecosystem in the Nevados National Natural Park (Nevados NNP) in Colombia. It was hypothesised that sites with potato crops and livestock farming would exhibit significant changes in soil physicochemical parameters and enzymatic activities compared with Páramo sites that have been conserved without agriculture. Samples were collected from soils under potato cultivation, livestock and Páramo (subject to the lowest degree of human intervention possible), on three farms in the El Bosque District at three different altitudes (Buenos Aires, El Edén and La Secreta) during two seasons (dry and rainy). The results showed that none of the physical parameters under study presented statistically significant differences due to the type of use (livestock, potato crop or Páramo), season of sampling (dry or rainy season) or altitude (different farms). The chemical parameters that statistically significantly differed due to land use were organic carbon, cation exchange capacity, calcium, potassium, and ammonium and those that showed statistically significant differences associated with the sampling timing were organic carbon, nitrogen, cation exchange capacity, total carbon, C/N and nitrate. Additionally, there were differences in organic carbon due to the altitude of the farms. With respect to enzymatic activities, those of β-glucosidase, phosphodiesterase and urease significantly decreased in soils under potato cultivation and livestock relative to those of Páramo, but those of acid phosphatase and protease increased significantly under potato cropping and livestock. The activities of β-glucosidase, acid phosphatase, alkaline phosphatase, phosphodiesterase and protease were higher during the dry season than the rainy season, and the activities of β-glucosidase, acid phosphatase and urease decreased statistically in the lower-altitude farm (La Secreta). These decreases in enzymatic activities are attributable to changes in the organic carbon of the soil. This study provides a novel insight on the relationships between land use and the physicochemical parameters and enzymatic activities of Páramo soils (which have been minimally studied to date) at different altitudes and during different seasons. The results suggest that changes in agricultural practices should be implemented to maintain the organic carbon of soil and, therefore, its enzymatic activities. Copyright © 2018 Elsevier B.V. All rights reserved.

Toxicological responses of red-backed salamander (Plethodon cinereus) exposed to aged and amended soils containing lead.

PubMed

Bazar, Matthew A; Quinn, Michael J; Mozzachio, Kristie; Bleiler, John A; Archer, Christine R; Phillips, Carlton T; Johnson, Mark S

2010-05-01

The use of lead in military and civilian small arms projectiles is widely acknowledged to have resulted in high soil lead concentrations at many small arms ranges. These ranges are often adjacent to wildlife habitat or have become habitat when no longer used. To assess the potential toxicity of lead to terrestrial amphibians in contaminated areas, we exposed 100 red-backed salamanders (Plethodon cinereus) to either a control soil or one of four soil treatments amended with lead acetate for 28 days. Analytical mean soil concentrations were 14 (control), 553, 1700, 4700, and 9167 mg Pb/kg soil dry weight. An additional 60 salamanders were also exposed for 28 days to one of six field-collected soil samples from a small arms range and a skeet range. The field soil concentrations ranged from 11 (background) to 16,967 mg Pb/kg soil dry weight. Food consisted of uncontaminated flightless Drosophila melanogaster. Salamander survival was reduced in amended soil treatments of 4700 and 9167 mg/kg by 15% and 80%, respectively. Inappetence was observed at 4700 and 9167 mg/kg and growth decreased in the 9167 mg/kg treatment. Total white blood cells decreased 32% at 4700 mg/kg compared to controls and were 22% lower in the 9167 mg/kg treatment. In contrast, survival was 100% for all field-collected soils with no hematological effects. At 16,967 mg/kg there was evidence of soil avoidance and decreased growth. These data suggest marked differences in toxicity and bioavailability of the lead-amended soil in contrast to the field-collected soil containing lead.

Effect of manure application on abundance of antibiotic resistance genes and their attenuation rates in soil: field-scale mass balance approach.

PubMed

Fahrenfeld, Nicole; Knowlton, Katharine; Krometis, Leigh Anne; Hession, W Cully; Xia, Kang; Lipscomb, Emily; Libuit, Kevin; Green, Breanna Lee; Pruden, Amy

2014-01-01

The development of models for understanding antibiotic resistance gene (ARG) persistence and transport is a critical next step toward informing mitigation strategies to prevent the spread of antibiotic resistance in the environment. A field study was performed that used a mass balance approach to gain insight into the transport and dissipation of ARGs following land application of manure. Soil from a small drainage plot including a manure application site, an unmanured control site, and an adjacent stream and buffer zone were sampled for ARGs and metals before and after application of dairy manure slurry and a dry stack mixture of equine, bovine, and ovine manure. Results of mass balance suggest growth of bacterial hosts containing ARGs and/or horizontal gene transfer immediately following slurry application with respect to ermF, sul1, and sul2 and following a lag (13 days) for dry-stack-amended soils. Generally no effects on tet(G), tet(O), or tet(W) soil concentrations were observed despite the presence of these genes in applied manure. Dissipation rates were fastest for ermF in slurry-treated soils (logarithmic decay coefficient of -3.5) and for sul1 and sul2 in dry-stack-amended soils (logarithmic decay coefficients of -0.54 and -0.48, respectively), and evidence for surface and subsurface transport was not observed. Results provide a mass balance approach for tracking ARG fate and insights to inform modeling and limiting the transport of manure-borne ARGs to neighboring surface water.

Lead bioaccumulation in Texas Harvester Ants (Pogonomyrmex barbatus) and toxicological implications for Texas Horned Lizard (Phrynosoma cornutum) populations of Bexar County, Texas.

PubMed

Burgess, Robert; Davis, Robert; Edwards, Deborah

2018-03-01

Uptake of lead from soil was examined in order to establish a site-specific ecological protective concentration level for the Texas Horned Lizard (Phrynosoma cornutum) at the Former Humble Refinery in San Antonio, Texas. Soils, harvester ants, and rinse water from the ants were analyzed at 11 Texas Harvester Ant (Pogonomyrmex barbatus) mounds. Soil concentrations at the harvester ant mounds ranged from 13 to 7474 mg/kg of lead dry weight. Ant tissue sample concentrations ranged from < 0.82 to 21.17 mg/kg dry weight. Rinse water concentrations were below the reporting limit in the majority of samples. Two uptake models were developed for the ants. A bioaccumulation factor model did not fit the data, as there was a strong decay in the calculated value with rising soil concentrations. A univariate natural log-transformed regression model produced a significant regression (p < .0001) with a high coefficient of determination (0.82), indicating a good fit to the data. Other diagnostic regression statistics indicated that the regression model could be reliably used to predict concentrations of lead in harvester ants from soil concentrations. Estimates of protective levels for P. cornutum were developed using published sub-chronic toxicological findings for the Western Fence Lizard that were allometricly adapted and compared to the Dose oral equation, which estimated lead consumed through ants plus incidental soil ingestion. The no observed adverse effect level toxicological limit for P. cornutum was estimated to be 5500 mg/kg.

Soil and surface layer type affect non-rainfall water inputs

NASA Astrophysics Data System (ADS)

Agam, Nurit; Berliner, Pedro; Jiang, Anxia

2017-04-01

Non-rainfall water inputs (NRWIs), which include fog deposition, dew formation, and direct water vapor adsorption by the soil, play a vital role in arid and semiarid regions. Environmental conditions, namely radiation, air temperature, air humidity, and wind speed, largely affect the water cycle driven by NRWIs. The substrate type (soil type and the existence/absence of a crust layer) may as well play a major role. Our objective was to quantify the effects of soil type (loess vs. sand) and surface layer (bare vs. crusted) on the gain and posterior evaporation of NRWIs in the Negev Highlands throughout the dry summer season. Four undisturbed soil samples (20 cm diameter and 50 cm depth) were excavated and simultaneously introduced into a PVC tube. Two samples were obtained in the Negev's Boker plain (loess soil) and two in the Nizzana sand dunes in the Western Negev. On one sample from each site the crust was removed while on the remaining one the natural crust was left in place. The samples were brought to the research site at the Jacob Bluestein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel (31˚08' N, 34˚53' E, 400 meter above the sea level) where they were exposed to the same environmental conditions. The four samples in their PVC tubes were placed on top of scales and the samples mass was continuously monitored. Soil temperatures were monitored at depths of 1, 2, 3, 5 and10 cm in each microlysimeter (ML) using Copper-Constantan thermocouples. The results of particle size distribution indicated that the crust of the loess soil is probably a physical crust, i.e., a crust that forms due to raindroplets impact; while the crust on the sand soil is biological. On most days, the loess soils adsorbed more water than their corresponding sand soil samples. For both soils, the samples for which the crust was removed adsorbed more water than the samples for which it was intact. The difference in daily water adsorption amount between crusted and non-crusted sandy soils often exceeded that between crusted and non-crusted loess soils.

Biopesticide effect of green compost against fusarium wilt on melon plants.

PubMed

Ros, M; Hernandez, M T; Garcia, C; Bernal, A; Pascual, J A

2005-01-01

The biopesticide effect of four green composts against fusarium wilt in melon plants and the effect of soil quality in soils amended with composts were assayed. The composts consisted of pruning wastes, with or without addition of coffee wastes (3/1 and 4/1, dry wt/dry wt) or urea (1000/1, dry wt/dry wt). In vitro experiments suggested the biopesticide effect of the composts against Fusarium oxysporum, while only the compost of pine bark and urea (1000/1dry wt/dry wt) had an abiotic effect. Melon plant growth with composts and F. oxysporum was one to four times greater than in the non-amended soil, although there was no significant decrease in the level of the F. oxysporum in the soil. The addition of composts to the soil also improved its biological quality, as assessed by microbiological and biochemical parameters: ATP and hydrolases involved in the P (phosphatase), C (beta-glucosidase) and N (urease) cycles. Green composts had greater beneficial characteristics, improved plant growth and controlled fusarium wilt in melon plants. These composts improve the soil quality of semi-arid agricultural soils. Biotic and abiotic factors from composts have been tested as responsible of their biopesticide activity against fusarium wilt.

Soil Modification by Native Shrubs Boosts Crop Productivity in Sudano-Sahelian Agroforestry System

NASA Astrophysics Data System (ADS)

Bogie, N. A.; Bayala, R.; Diedhiou, I.; Ghezzehei, T. A.; Dick, R.

2014-12-01

A changing climate along with human and animal population pressure can have a devastating effect on crop yields and food security in the Sudano-Sahel. Agricultural solutions to address soil degradation and crop water stress are needed to combat this increasingly difficult situation. Significant differences in crop success have been observed in peanut and millet grown in association with two native evergreen shrubs Piliostigma reticulatum, and Guiera senegalensis at the sites of Nioro du Rip and Keur Matar, respectively.We investigate how farmers can increase crop productivity by capitalizing on the evolutionary adaptation of native shrubs to the harsh Sudano-Sahelian environment as well as the physical mechanisms at work in the system that can lead to more robust yields. Soil moisture and water potential data were collected during a dry season millet irrigation experiment where stress was imposed in the intercropped system. Despite lower soil moisture content, crops grown in association with shrubs have increased biomass production and a faster development cycle. Hydraulic redistribution is thought to exist in this system and we found diurnal fluctuations in water potential within the intercropped system that increased in magnitude of to 0.4 Mpa per day as the soil dried below 1.0 Mpa during the stress treatment. An isotopic tracer study investigating hydraulic redistribution was carried out by injecting labeled water into shrub roots and sampling shrubs and nearby crops for isotopic analysis of plant water. These findings build on work that was completed in 2004 at the site, but point to lower overall magnitude of diurnal soil water potential fluctuations in dry soils. Using even the limited resources that farmers possess, this agroforestry technique can be expanded over wide swaths of the Sahel.

Pesticide storage and release in unsaturated soil in Illinois, USA

USGS Publications Warehouse

Roy, W.R.; Krapac, I.G.; Chou, S.-F.J.; Simmons, F.W.

2001-01-01

The chemical fate and movement of pesticides may be subject to transient storage in unsaturated soils during periods of light rainfall, and subsequent release into shallow groundwater by increased rainfall. The objective of this study was to conduct field-scale experiments to determine the relative importance of transient storage and subsequent release of agrichemicals from the vadose zone into potential aquifers. Two field-scale experiments were conducted under a rain exclusion shelter. In the 1 x experiment, atrazine and chlorpyrifos were applied at application-rate equivalents (1.6 kg ha-1 and 1.3 kg ha-1, respectively). In the 4x experiment, atrazine was applied in an amount that was four times greater than that usually applied to fields (6.7 kg ha-1). Water was either applied to simulate rain or withheld to simulate dry periods. In the 1 x experiment, atrazine was detected in the water samples whereas chlorpyrifos was not detected in the majority of the samples. The dry period imposed on the treatment plot did not appear to result in storage of the chemicals, whereas the wet period resulted in greater leaching of atrazine, although the concentrations remained less than the Maximum Contaminant Level of 3 ?? L-1. Both chemicals were detected in soil samples collected from a 20- to 30-cm depth, but it appeared that both chemicals dissipated before the field experiment was concluded. It appeared that the one-time application of atrazine and chlorpyrifos at the label rates did not result in a sufficient mass to be stored and flushed in significant concentrations to the saturated zone. When atrazine was applied at 4x and a longer drought period was imposed on the treatment plot, the resulting concentrations of dissolved atrazine were still less than 3 ??g L-1. Atrazine was detected in only the near-surface (0 to 15 cm) soil samples and the herbicide dissipated before the onset of the dry period in the treatment plot. The results of this field study demonstrated that atrazine and chlorpyrifos were not sufficiently persistent to be stored and then released in significantly large concentrations to the saturated zone. The dissipation half-life of atrazine in the 4x application was about 44 days. This study, in addition to others, suggested that atrazine may be less persistent in surface soil than has been generally reported.

Nitrogen metabolism correlates with the acclimation of photosynthesis to short-term water stress in rice (Oryza sativa L.).

PubMed

Zhong, Chu; Cao, Xiaochuang; Bai, Zhigang; Zhang, Junhua; Zhu, Lianfeng; Huang, Jianliang; Jin, Qianyu

2018-04-01

Nitrogen metabolism is as sensitive to water stress as photosynthesis, but its role in plant under soil drying is not well understood. We hypothesized that the alterations in N metabolism could be related to the acclimation of photosynthesis to water stress. The features of photosynthesis and N metabolism in a japonica rice 'Jiayou 5' and an indica rice 'Zhongzheyou 1' were investigated under mild and moderate soil drying with a pot experiment. Soil drying increased non-photochemical quenching (NPQ) and reduced photon quantum efficiency of PSII and CO 2 fixation in 'Zhongzheyou 1', whereas the effect was much slighter in 'Jiayou 5'. Nevertheless, the photosynthetic rate of the two cultivars showed no significant difference between control and water stress. Soil drying increased nitrate reducing in leaves of 'Zhongzheyou 1', characterized by enhanced nitrate reductase (NR) activity and lowered nitrate content; whereas glutamate dehydrogenase (GDH), glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) were relative slightly affected. 'Jiayou 5' plants increased the accumulation of nitrate under soil drying, although its NR activity was increased. In addition, the activities of GDH, GOT and GPT were typically increased under soil drying. Besides, amino acids and soluble sugar were significantly increased under mild and moderate soil drying, respectively. The accumulation of nitrate, amino acid and sugar could serve as osmotica in 'Jiayou 5'. The results reveal that N metabolism plays diverse roles in the photosynthetic acclimation of rice plants to soil drying. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing Season in the Coastal Zone of Yellow River Delta

PubMed Central

Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei

2014-01-01

The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 2− and Na+ were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m−2, in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 −–N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 +–N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 −–N and NH4 +–N was ~31.38% and ~20.50% for the contents of NO3 −–N and NH4 +–N in 0–10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD. PMID:24977238

Presence and distribution of wastewater-derived pharmaceuticals in soil irrigated with reclaimed water

USGS Publications Warehouse

Kinney, C.A.; Furlong, E.T.; Werner, S.L.; Cahill, J.D.

2006-01-01

Three sites in the Front Range of Colorado, USA, were monitored from May through September 2003 to assess the presence and distribution of pharmaceuticals in soil irrigated with reclaimed water derived from urban wastewater. Soil cores were collected monthly, and 19 pharmaceuticals, all of which were detected during the present study, were measured in 5-cm increments of the 30-cm cores. Samples of reclaimed water were analyzed three times during the study to assess the input of pharmaceuticals. Samples collected before the onset of irrigation in 2003 contained numerous pharmaceuticals, likely resulting from the previous year's irrigation. Several of the selected pharmaceuticals increased in total soil concentration at one or more of the sites. The four most commonly detected pharmaceuticals were erythromycin, carbamazepine, fluoxetine, and diphenhydramine. Typical concentrations of the individual pharmaceuticals observed were low (0.02-15 ??g/kg dry soil). The existence of subsurface maximum concentrations and detectable concentrations at the lowest sampled soil depth might indicate interactions of soil components with pharmaceuticals during leaching through the vadose zone. Nevertheless, the present study demonstrates that reclaimed-water irrigation results in soil pharmaceutical concentrations that vary through the irrigation season and that some compounds persist for months after irrigation. ?? 2006 SETAC.

A method for soil moisture probes calibration and validation of satellite estimates.

PubMed

Holzman, Mauro; Rivas, Raúl; Carmona, Facundo; Niclòs, Raquel

2017-01-01

Optimization of field techniques is crucial to ensure high quality soil moisture data. The aim of the work is to present a sampling method for undisturbed soil and soil water content to calibrated soil moisture probes, in a context of the SMOS (Soil Moisture and Ocean Salinity) mission MIRAS Level 2 soil moisture product validation in Pampean Region of Argentina. The method avoids soil alteration and is recommended to calibrated probes based on soil type under a freely drying process at ambient temperature. A detailed explanation of field and laboratory procedures to obtain reference soil moisture is shown. The calibration results reflected accurate operation for the Delta-T thetaProbe ML2x probes in most of analyzed cases (RMSE and bias ≤ 0.05 m 3 /m 3 ). Post-calibration results indicated that the accuracy improves significantly applying the adjustments of the calibration based on soil types (RMSE ≤ 0.022 m 3 /m 3 , bias ≤ -0.010 m 3 /m 3 ). •A sampling method that provides high quality data of soil water content for calibration of probes is described.•Importance of calibration based on soil types.•A calibration process for similar soil types could be suitable in practical terms, depending on the required accuracy level.

Brassica cover crops for nitrogen retention in the Mid-Atlantic coastal plain.

PubMed

Dean, Jill E; Weil, Ray R

2009-01-01

Brassica cover crops are new to the mid-Atlantic region, and limited information is available on their N uptake capabilities for effective N conservation. Forage radish (Raphanus sativus L. cv. Daikon), oilseed radish (Raphanus sativus L. cv. Adagio), and rape (Brassica napus L. cv. Dwarf Essex) were compared with rye (Secale cereale L. cv. Wheeler), a popular cover crop in the region, with regard to N uptake ability and potential to decrease N leaching at two sites in Maryland. Plants were harvested in fall and spring for dry matter and N analysis. Soil samples from 0 cm to 105 to 180 cm depth were obtained in fall and spring for NH(4)-N and NO(3)-N analyses. Ceramic cup tension lysimeters were installed at depths of 75 to 120 cm to monitor NO(3)-N in soil pore water. Averaged across 3 site-years, forage radish and rape shoots had greater dry matter production and captured more N in fall than rye shoots. Compared with a weedy fallow control, rape and rye caused similar decreases in soil NO(3)-N in fall and spring throughout the sampled profile. Cover crops had no effect on soil NH(4)-N. During the spring on coarse textured soil, pore water NO(3)-N concentrations in freeze-killed Brassica (radish) plots were greater than in control and overwintering Brassica (rape) and rye plots. On fine textured soil, all cover crops provided a similar decrease in pore water NO(3)-N concentration compared with control. On coarse textured soils, freeze-killed Brassica cover crops should be followed by an early-planted spring main crop.

Field-Scale Transplantation Experiment To Investigate Structures of Soil Bacterial Communities at Pioneering Sites▿†

PubMed Central

Lazzaro, Anna; Gauer, Andreas; Zeyer, Josef

2011-01-01

Studies on the effect of environmental conditions on plants and microorganisms are a central issue in ecology, and they require an adequate experimental setup. A strategy often applied in geobotanical studies is based on the reciprocal transplantation of plant species at different sites. We adopted a similar approach as a field-based tool to investigate the relationships of soil bacterial communities with the environment. Soil samples from two different (calcareous and siliceous) unvegetated glacier forefields were reciprocally transplanted and incubated for 15 months between 2009 and 2010. Controls containing local soils were included. The sites were characterized over time in terms of geographical (bedrock, exposition, sunlight, temperature, and precipitation) and physicochemical (texture, water content, soluble and nutrients) features. The incubating local (“home”) and transplanted (“away”) soils were monitored for changes in extractable nutrients and in the bacterial community structure, defined through terminal restriction fragment length polymorphism (T-RFLP) of the 16S rRNA gene. Concentrations of soluble ions in most samples were more significantly affected by seasons than by the transplantation. For example, NO3− showed a seasonal pattern, increasing from 1 to 3 μg NO3− (g soil dry weight)−1 after the melting of snow but decreasing to <1 μg NO3− (g soil dry weight)−1 in autumn. Seasons, and in particular strong precipitation events occurring in the summer of 2010 (200 to 300 mm of rain monthly), were also related to changes of bacterial community structures. Our results show the suitability of this approach to compare responses of bacterial communities to different environmental conditions directly in the field. PMID:21965395

Influence of Dry Soil on the Ability of Formosan Subterranean Termites, Coptotermes formosanus, to Locate Food Sources

PubMed Central

Cornelius, Mary L.; Osbrink, Weste L.A.

2011-01-01

The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three—chambered apparatus were compared between treatments with dry soil in the center container and treatments where the soil in the center container was moist. When a wood block was located in the release container, termites fed significantly more on that block, regardless of treatment or soil type. In the treatment with dry clay, none of the termites tunneled through the dry clay barrier to reach the distal container. When termites had to tunnel through a barrier of dry sand, topsoil, or clay to reach the sole wood block, there was no effect on wood consumption for the sand treatment, but there was significantly less feeding on wood in the treatments with dry topsoil or clay. When foraging arenas had a section of dry sand in the center, the dry sand significantly reduced tunneling in the distal section after 3 days, but not after 10 days. There was a highly significant effect on the ability of termites to colonize food located in dry sand. Only one feeding station located in dry sand was colonized by termites, compared with 11 feeding stations located in moist sand. PMID:22239343

Survey and evaluation of contaminants in earthworms and in soils derived from dredged material at confined disposal facilities in the Great Lakes region

USGS Publications Warehouse

Beyer, W.N.; Stafford, C.

1993-01-01

Soils derived from dredged material were collected, together with earthworms from nine confined disposal facilities located in the Great Lakes Region. These samples were analyzed for 18 elements, 11 organochlorine pesticides, PCBs, and 24 polycyclic aromatic hydrocarbons. The concentrations detected in earthworms were evaluated in terms of their potential hazard to wildlife, which for the sake of the evaluation were assumed to prey entirely either on earthworms or on other soil invertebrates having similar concentrations. The soil concentrations (dry wt.) of the contaminants of greatest concern were < 1.9 to 32 ppm Cd, < 0.053 to 0.94 ppm Hg, 4.6 to 550 ppm Pb, and < 0.1 to 1.0 ppm PCBs. The concentrations in earthworms (dry wt., ingested soil included) were as high as 91 ppm Cd, 1.6 ppm Hg, 200 ppm Pb, and 1.8 ppm PCBs. Based on laboratory toxicity studies of relatively sensitive species, and on concentration factors calculated from the earthworm and soil data, we estimated that lethal or serious sublethal effects on wildlife might be expected at concentrations of 10 ppm Cd, 3 ppm Hg, 670 ppm Pb, and 1.7 ppm PCBs in alkaline surface soils derived from dredged material. Concentrations of polycyclic aromatic hydrocarbons in earthworms were well below those in soil.

Topsoil moisture mapping using geostatistical techniques under different Mediterranean climatic conditions.

PubMed

Martínez-Murillo, J F; Hueso-González, P; Ruiz-Sinoga, J D

2017-10-01

Soil mapping has been considered as an important factor in the widening of Soil Science and giving response to many different environmental questions. Geostatistical techniques, through kriging and co-kriging techniques, have made possible to improve the understanding of eco-geomorphologic variables, e.g., soil moisture. This study is focused on mapping of topsoil moisture using geostatistical techniques under different Mediterranean climatic conditions (humid, dry and semiarid) in three small watersheds and considering topography and soil properties as key factors. A Digital Elevation Model (DEM) with a resolution of 1×1m was derived from a topographical survey as well as soils were sampled to analyzed soil properties controlling topsoil moisture, which was measured during 4-years. Afterwards, some topography attributes were derived from the DEM, the soil properties analyzed in laboratory, and the topsoil moisture was modeled for the entire watersheds applying three geostatistical techniques: i) ordinary kriging; ii) co-kriging considering as co-variate topography attributes; and iii) co-kriging ta considering as co-variates topography attributes and gravel content. The results indicated topsoil moisture was more accurately mapped in the dry and semiarid watersheds when co-kriging procedure was performed. The study is a contribution to improve the efficiency and accuracy of studies about the Mediterranean eco-geomorphologic system and soil hydrology in field conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Occurrence of veterinary antibiotics and progesterone in broiler manure and agricultural soil in Malaysia.

PubMed

Ho, Yu Bin; Zakaria, Mohamad Pauzi; Latif, Puziah Abdul; Saari, Nazamid

2014-08-01

Repeated applications of animal manure as fertilizer are normal agricultural practices that may release veterinary antibiotics and hormones into the environment from treated animals. Broiler manure samples and their respective manure-amended agricultural soil samples were collected in selected locations in the states of Selangor, Negeri Sembilan and Melaka in Malaysia to identify and quantify veterinary antibiotic and hormone residues in the environment. The samples were analyzed using ultrasonic extraction followed by solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The broiler manure samples were found to be contaminated with at least six target analytes, namely, doxycycline, enrofloxacin, flumequine, norfloxacin, trimethoprim and tylosin. These analytes were detected in broiler manure samples with maximum concentrations reaching up to 78,516 μg kg(-1) dry weight (DW) (doxycycline). For manure-amended agricultural soil samples, doxycycline and enrofloxacin residues were detected in every soil sample. The maximum concentration of antibiotic detected in soil was 1331 μg kg(-1) DW (flumequine). The occurrence of antibiotics and hormones in animal manure at high concentration poses a risk of contaminating agricultural soil via fertilization with animal manure. Some physico-chemical parameters such as pH, total organic carbon (TOC) and metal content played a considerable role in the fate of the target veterinary antibiotics and progesterone in the environment. It was suggested that these parameters can affect the adsorption of pharmaceuticals to solid environmental matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Microbial community dynamics induced by rewetting dry soil: summer precipitation matters

NASA Astrophysics Data System (ADS)

Barnard, Romain; Osborne, Catherine; Firestone, Mary

2015-04-01

The massive soil CO2 efflux associated with rewetting dry soils after the dry summer period significantly contributes to the annual carbon budget of Mediterranean grasslands. Rapid reactivation of soil heterotrophic activity and available carbon are both required to fuel the CO2 pulse. Better understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting future changes in carbon cycling. We investigated the effects of a controlled rewetting event on the soil CO2 efflux pulse and on the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores previously subjected to three different precipitation patterns over four months (full summer dry season, extended wet season, and absent dry season). Phylogenetic marker genes for bacteria (16S) and fungi (28S) were sequenced before and after rewetting, and the abundance of these genes and transcripts was measured. Even after having experienced markedly different antecedent water conditions, the potentially active bacterial communities showed a consistent wet-up response, reflecting contrasting life-strategies for different groups. Moreover, we found a significant positive relation between the extent of change in the structure of the potentially active bacterial community and the magnitude of the CO2 pulse upon rewetting dry soils. We suggest that the duration of severe dry conditions (predicted to change under future climate) is important in conditioning the response potential of the soil bacterial community to wet-up as well as in framing the magnitude of the associated CO2 pulse.

Western US high June 2015 temperatures and their relation to global warming and soil moisture

NASA Astrophysics Data System (ADS)

Philip, Sjoukje Y.; Kew, Sarah F.; Hauser, Mathias; Guillod, Benoit P.; Teuling, Adriaan J.; Whan, Kirien; Uhe, Peter; Oldenborgh, Geert Jan van

2018-04-01

The Western US states Washington (WA), Oregon (OR) and California (CA) experienced extremely high temperatures in June 2015. The temperature anomalies were so extreme that they cannot be explained with global warming alone. We investigate the hypothesis that soil moisture played an important role as well. We use a land surface model and a large ensemble from the weather@home modelling effort to investigate the coupling between soil moisture and temperature in a warming world. Both models show that May was anomalously dry, satisfying a prerequisite for the extreme heat wave, and they indicate that WA and OR are in a wet-to-dry transitional soil moisture regime. We use two different land surface-atmosphere coupling metrics to show that there was strong coupling between temperature, latent heat flux and the effect of soil moisture deficits on the energy balance in June 2015 in WA and OR. June temperature anomalies conditioned on wet/dry conditions show that both the mean and extreme temperatures become hotter for dry soils, especially in WA and OR. Fitting a Gaussian model to temperatures using soil moisture as a covariate shows that the June 2015 temperature values fit well in the extrapolated empirical temperature/drought lines. The high temperature anomalies in WA and OR are thus to be expected, given the dry soil moisture conditions and that those regions are in the transition from a wet to a dry regime. CA is already in the dry regime and therefore the necessity of taking soil moisture into account is of lower importance.

Diversity of micro-fungi in an Antarctic dry valley

NASA Technical Reports Server (NTRS)

Baublis, J. A.; Wharton, R. A. Jr; Volz, P. A.; Wharton RA, J. r. (Principal Investigator)

1991-01-01

The fungal microflora of a dry valley in Southern Victoria Land near McMurdo Sound, Antarctica, was investigated. Samples were collected from introduced objects such as a mummified penguin and spent chewing tobacco in addition to the sparse soil found in rock fissures, isolated moss colonies, shoreline deposit materials, CaCO3 precipitates, and microbial mat debris obtained from the frozen surface of the lake in the basin of Taylor Valley. Using conventional media and techniques, all collection sites yielded populations of yeasts and filamentous fungi. Water samples and live microbial mats from beneath the lake ice yielded species of fungi along with an abundance of bacteria.

Characteristics and impacts of trace elements in atmospheric deposition at a high-elevation site, southern China.

PubMed

Nie, Xiaoling; Wang, Yan; Li, Yaxin; Sun, Lei; Li, Tao; Yang, Minmin; Yang, Xueqiao; Wang, Wenxing

2017-10-01

To investigate the regional background trace element (TE) level in atmospheric deposition (dry and wet), TEs (Fe, Al, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, and Pb) in 52 rainwater samples and 73 total suspended particles (TSP) samples collected in Mt. Lushan, Southern China, were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The results showed that TEs in wet and dry deposition of the target area were significantly elevated compared within and outside China and the volume weight mean pH of rainwater was 4.43. The relative contributions of wet and dry depositions of TEs vary significantly among elements. The wet deposition fluxes of V, As, Cr, Se, Zn, and Cd exceeded considerably their dry deposition fluxes while dry deposition dominated the removal of pollution elements such as Mo, Cu, Ni, Mn, and Al. The summed dry deposition flux was four times higher than the summed wet deposition flux. Prediction results based on a simple accumulation model found that the content of seven toxic elements (Cr, Ni, Cu, Zn, As, Cd, and Pb) in soils could increase rapidly due to the impact of annual atmospheric deposition, and the increasing amounts of them reached 0.063, 0.012, 0.026, 0.459, 0.076, 0.004, and 0.145 mg kg -1 , respectively. In addition, the annual increasing rates ranged from 0.05% (Cr and Ni) to 2.08% (Cd). It was also predicted that atmospheric deposition induced the accumulation of Cr and Cd in surface soils. Cd was the critical element with the greatest potential ecological risk among all the elements in atmospheric deposition.

Impact of drying-rewetting events on the response of soil microbial functions to dairyfibre and Miscanthus biochars

NASA Astrophysics Data System (ADS)

Bonnett, Sam; Vink, Stefanie; Baker, Kate; Saghir, Muhammad; Hornung, Andreas

2014-05-01

Biochar application has been shown to positively affect soil microbial functions such as reducing greenhouse gas emissions, increasing water/nutrient availability and increasing crop yields in tropical regions (Lehmann & Joseph, 2009). Understanding the dynamics of biochar application to soil microbial processes is critical for ensuring that soil quality, integrity and sustainability of the soil sub-system are maintained for crop growth. The aim of this British Ecological Society (BES) funded study was to examine the effect of two types of biochar on soil physicochemistry, GHG production, soil enzyme activities and microbial biomass in typical agricultural soil types and whether the effects were altered by drying, rewetting and flooding events. Miscanthus and dairyfibre (a mixture of straw and manure) feedstocks from Harper Adams University were pyrolyzed by Aston University at 450 °C using 100 kg/hr pyroformer technology. Two sieved soil types (sandy loam and clay loam) were mixed with dry biochar to produce 2 and 10 % w/w treatments for comparison with controls and maintained at 15 °C in temperature controlled incubators. At 0, 22, 44, 80, 101, and 114 days, soil was collected for determination of heterotrophic respiration, and microbial biomass by substrate-induced respiration (SIR), by gas headspace incubation and analysis of carbon dioxide (CO2) and nitrous oxide (N2O) by gas chromatography. Soil was sampled for the determination of water-extractable carbon, pH, and extracellular enzyme activities. Soil samples were maintained at field gravimetric water content between 0 and 44 days; air dried between 44 and 80 days; rewetted between 80 and 101 days; and flooded between 101 to 114 days. Results showed that the impact of biochar on soil microbial processes was dependent on biochar type and soil type, the level of biochar application and changes in soil moisture. Biochar affected soil pH particularly within the dairyfibre treatments, potentially due to the dissolution of alkaline minerals, high ash content (Lehmann et al. 2011) and solubility of DOC. Biochar treatments buffered changes in pH caused by drying and flooding but resulted in an increase in DOC. Biochar in general stabilised glucosidase activity whilst Miscanthus biochar stimulated chitinase and phosphatase activity that may have been due to adsorption of either enzyme or substrate as observed by Bailey et al. (2011). Surprisingly, alkaline phosphatase activity was not stimulated by the rise in pH in the diaryfibre treatment and was lower than the control along with the other hydrolase enzymes suggesting that deprotonation of soil phenols at higher pH inhibited activity via the enzyme-latch mechanism that in peatlands explains low rates of decomposition (Freeman et al., 2001; Sinsabaugh et al. 2010). This was supported by observation of higher phenol oxidase activity within the dairyfibre treatment that increased in response to greater availability of substrate and/or increases in pH. All biochars inhibited the production of N2O that was stimulated by the supply of labile carbon from SIR, suggesting that biochar decreased C-substrate availability through adsorption at its surface (Clough and Condron, 2010). Overall, this study has shown that specific feedstocks may be used to produce biochars to control microbial functions in soil such as inhibiting hydrolase enzymes for carbon sequestration as occurs naturally in peatlands or suppress the production of the potent greenhouse gas N2O. References Bailey, V., Fansler, S.J., Smith, J.L. Bolton, H. (2011) Reconciling apparent variability in effects of biochar amendment on soil enzyme activities by assay optimization. Soil Biology and Biochemistry 43, 296-301. Clough, T. and Condron, L. (2010) Biochar and the nitrogen cycle: introduction. Journal of Environmental Quality, 39,1218-1223. Freeman, C., Ostle, N. and Kang, H. (2001) An enzymic 'latch' on a global carbon store. Nature 409, 149. Lehmann, J and Joseph, S (2009). Biochar for Environmental Management. Earthscan, London. Lehmann, J., Rillig, M.C., Thies, J., Masiello, C.A., Hockaday, W.C. and Crowley, D. (2011) Biochar effects on soil biota - A review. Soil Biology and Biochemistry 43, 1812-1836. Sinsabaugh, R.L. (2010) Phenol oxidase, peroxidase and organic matter dynamics of soil. Soil Biology and Biochemistry 42, 391-404.

Cadmium in animal production and its potential hazard on Beijing and Fuxin farmlands.

PubMed

Li, Yan-xia; Xiong, Xiong; Lin, Chun-ye; Zhang, Feng-song; Wei, Li; Wei, Han

2010-05-15

A random sample of pairs of animal feeds and manures were collected from 215 animal barns in Beijing and Fuxin regions of China. The concentrations of Cd in manures and feeds ranged from non-detectable to 129.8 mg/kg dry weight and non-detectable to 31 mg/kg dry weight, respectively. The concentrations of Cd in pig, dairy cow and chicken manures were positively correlated to those in their feeds. About 30% of the manure samples contained Cd concentrations higher than the upper limit for use in farmlands, and pig and chicken manures might be the primary contributors of Cd to farmlands. The farmlands in Beijing and around the Fuxin Downtown areas would exceed the soil quality criteria within several decades according to current manure Cd loading rates. Undoubtedly, more scientific animal production and manure management practices to minimize soil pollution risks are necessary for the two regions. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Forensic identification of blood in the presence of contaminations using Raman microspectroscopy coupled with advanced statistics: effect of sand, dust, and soil.

PubMed

Sikirzhytskaya, Aliaksandra; Sikirzhytski, Vitali; McLaughlin, Gregory; Lednev, Igor K

2013-09-01

Body fluid traces recovered at crime scenes are among the most common and important types of forensic evidence. However, the ability to characterize a biological stain at a crime scene nondestructively has not yet been demonstrated. Here, we expand the Raman spectroscopic approach for the identification of dry traces of pure body fluids to address the problem of heterogeneous contamination, which can impair the performance of conventional methods. The concept of multidimensional Raman signatures was utilized for the identification of blood in dry traces contaminated with sand, dust, and soil. Multiple Raman spectra were acquired from the samples via automatic scanning, and the contribution of blood was evaluated through the fitting quality using spectroscopic signature components. The spatial mapping technique allowed for detection of "hot spots" dominated by blood contribution. The proposed method has great potential for blood identification in highly contaminated samples. © 2013 American Academy of Forensic Sciences.

Paratrechina longicornis ants in a tropical dry forest harbor specific Actinobacteria diversity.

PubMed

Reyes, Ruth D Hernández; Cafaro, Matías J

2015-01-01

The diversity of Actinobacteria associated with Paratrechina longicornis, an ant species that prefers a high protein diet, in a subtropical dry forest (Guánica, Puerto Rico) was determined by culture methods and by 16S rDNA clone libraries. The results of both methodologies were integrated to obtain a broader view of the diversity. Streptomyces, Actinomadura, Nocardia, Ornithinimicrobium, Tsukamurella, Brevibacterium, Saccharopolyspora, Nocardioides, Microbacterium, Leifsonia, Pseudonocardia, Corynebacterium, Geodermatophilus, Amycolatopsis, and Nonomuraea were found associated with the ants. The genera Streptomyces and Actinomadura were the most abundant. Also, the diversity of Actinobacteria associated with the soil surrounding the nest was determined using 16S rDNA clone libraries. In total, 27 genera of Actinobacteria were associated with the nest soils. A dominant genus was not observed in any of the soil samples. We compared statistically the Actinobacteria communities among P. longicornis nests and each nest with its surrounding soil using the clone libraries data. We established that the communities associated with the ants were consistent and significantly different from those found in the soil in which the ants live. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aridity and plant uptake interact to make dryland soils hotspots for nitric oxide (NO) emissions

PubMed Central

Blankinship, Joseph C.; Marchus, Kenneth; Lucero, Delores M.; Sickman, James O.; Schimel, Joshua P.

2016-01-01

Nitric oxide (NO) is an important trace gas and regulator of atmospheric photochemistry. Theory suggests moist soils optimize NO emissions, whereas wet or dry soils constrain them. In drylands, however, NO emissions can be greatest in dry soils and when dry soils are rewet. To understand how aridity and vegetation interact to generate this pattern, we measured NO fluxes in a California grassland, where we manipulated vegetation cover and the length of the dry season and measured [δ15-N]NO and [δ18-O]NO following rewetting with 15N-labeled substrates. Plant N uptake reduced NO emissions by limiting N availability. In the absence of plants, soil N pools increased and NO emissions more than doubled. In dry soils, NO-producing substrates concentrated in hydrologically disconnected microsites. Upon rewetting, these concentrated N pools underwent rapid abiotic reaction, producing large NO pulses. Biological processes did not substantially contribute to the initial NO pulse but governed NO emissions within 24 h postwetting. Plants acted as an N sink, limiting NO emissions under optimal soil moisture. When soils were dry, however, the shutdown in plant N uptake, along with the activation of chemical mechanisms and the resuscitation of soil microbial processes upon rewetting, governed N loss. Aridity and vegetation interact to maintain a leaky N cycle during periods when plant N uptake is low, and hydrologically disconnected soils favor both microbial and abiotic NO-producing mechanisms. Under increasing rates of atmospheric N deposition and intensifying droughts, NO gas evasion may become an increasingly important pathway for ecosystem N loss in drylands. PMID:27114523

Petroleum contaminated soil in Oman: evaluation of bioremediation treatment and potential for reuse in hot asphalt mix concrete.

PubMed

Jamrah, Ahmad; Al-Futaisi, Ahmed; Hassan, Hossam; Al-Oraimi, Salem

2007-01-01

This paper presents a study that aims at evaluating the leaching characteristics of petroleum contaminated soils as well as their application in hot mix asphalt concrete. Soil samples are environmentally characterized in terms of their total heavy metals and hydrocarbon compounds and leachability. The total petroleum hydrocarbon (TPH) present in the PCS before and after treatment was determined to be 6.8% and 5.3% by dry weight, indicating a reduction of 1% in the TPH of PCS due to the current treatment employed. Results of the total heavy metal analysis on soils indicate that the concentrations of heavy metals are lower when extraction of the soil samples is carried out using hexane in comparison to TCE. The results show that the clean soils present in the vicinity of contaminated sites contain heavy metals in the following decreasing order: nickel (Ni), followed by chromium (Cr), zinc (Zn), copper (Cu), lead (Pb), and vanadium (V). The current treatment practice employed for remediation of the contaminated soil reduces the concentrations of nickel and chromium, but increases the concentrations of all remaining heavy metals.

Natural 'background' soil water repellency in conifer forests: its prediction and relationship to wildfire occurrence

NASA Astrophysics Data System (ADS)

Doerr, Stefan; Woods, Scott; Martin, Deborah; Casimiro, Marta

2013-04-01

Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by col- lecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were fur- ther analyzed for repellency using WDPT and contact angle (hsl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelma- nii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long- unburnt conifer forest soils of the north-western USA is therefore incorrect. It follows that, where pre-fire water repellency levels are not known or highly variable, post-fire soil water repellency conditions are an unreliable indicator in classifying soil burn severity. The terrain and soil variables examined showed, overall, no convincing relationship with the repellency levels observed (R2 < 0.15) except that repellency was limited in soils (i) developed over meta-sedimen- tary lithology and (ii) with clay contents >4%. This suggests that water repellency levels cannot be pre- dicted with confidence from common terrain or soil variables. This work is presented in the memory of the late Scott Woods, who was instrumental in the success of this study and an inspiration to us all.

Playa Soil Moisture and Evaporation Dynamics During the MATERHORN Field Program

NASA Astrophysics Data System (ADS)

Hang, Chaoxun; Nadeau, Daniel F.; Jensen, Derek D.; Hoch, Sebastian W.; Pardyjak, Eric R.

2016-06-01

We present an analysis of field data collected over a desert playa in western Utah, USA in May 2013, the most synoptically active month of the year, as part of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. The results show that decreasing surface albedo, decreasing Bowen ratio and increasing net radiation with increasing soil moisture sustained a powerful positive feedback mechanism promoting large evaporation rates immediately following rain events. Additionally, it was found that, while nocturnal evaporation was negligible during dry periods, it was quite significant (up to 30 % of the daily cumulative flux) during nights following rain events. Our results further show that the highest spatial variability in surface soil moisture is found under dry conditions. Finally, we report strong spatial heterogeneities in evaporation rates following a rain event. The cumulative evaporation for the different sampling sites over a five-day period varied from ≈ 0.1 to ≈ 6.6 mm. Overall, this study allows us to better understand the mechanisms underlying soil moisture dynamics of desert playas as well as evaporation following occasional rain events.

Site Simulation of Solidified Peat: Lab Monitoring

NASA Astrophysics Data System (ADS)

Durahim, N. H. Ab; Rahman, J. Abd; Tajuddin, S. F. Mohd; Mohamed, R. M. S. R.; Al-Gheethi, A. A.; Kassim, A. H. Mohd

2018-04-01

In the present research, the solidified peat on site simulation is conducted to obtain soil leaching from soil column study. Few raw materials used in testing such as Ordinary Portland Cement (OPC), Fly ash (FA) and bottom ash (BA) which containing in solidified peat (SP), fertilizer (F), and rainwater (RW) are also admixed in soil column in order to assess their effects. This research was conducted in two conditions which dry and wet condition. Distilled water used to represent rainfall during flushing process while rainwater used to gain leaching during dry and wet condition. The first testing made after leaching process done was Moisture Content (MC). Secondly, Unconfined Compressive Strength (UCS) will be conducted on SP to know the ability of SP strength. These MC and UCS were made before and after SP were applied in soil column. Hence, the both results were compared to see the reliability occur on SP. All leachate samples were tested using Absorption Atomic Spectroscopy (AAS), Ion Chromatography (IC) and Inductively-Coupled Plasma Spectrophotometry (ICP-MS) testing to know the anion and cation present in it.

Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils.

PubMed

Figueiredo, Estela; Soares, M Elisa; Baptista, Paula; Castro, Marisa; Bastos, M Lourdes

2007-08-22

An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight, and for Cr(VI), the mean values were 0.103 and 0.143 microg/g of dry weight for cap and stalk, respectively. For soils, the mean concentrations found were, for total Cr, 84.0 microg/g and, for Cr(VI), 0.483 microg/g. The bioconcentration factors (BCFs) based on dry weight for cap and stalk were determined, and the values found, for both total Cr and Cr(VI), were always <1, although for hexavalent chromium, the BCFs were 10 times higher than for total chromium.

Evaluation of some pollutant levels in environmental samples collected from the area of the new campus of Taif University.

PubMed

Sharshar, Taher; Hassan, H Ebrahim; Arida, Hassan A; Aydarous, Abdulkadir; Bazaid, Salih A; Ahmed, Mamdouh A

2013-01-01

The levels of radioactivity and heavy metals in soil, plant and groundwater samples collected from the area of the new campus of Taif University, Saudi Arabia, and its neighbouring areas have been determined. High-resolution gamma-ray spectroscopy was used for radioactivity measurements, and inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of heavy metals. The means of (226)Ra, (228)Ra and (40)K concentrations in water samples collected from four wells were found to be 0.13 ± 0.03, 0.05 ± 0.03 and 1.3 ± 0.5 Bq l(-1), respectively. The means of (238)U, (226)Ra, (228)Ra ((232)Th for soil samples) and (40)K concentrations in wild plant and soil samples were found to be 3.7 ± 4.1, 8.8 ± 11.6, 3.8 ± 2.9 and 1025 ± 685, and 8.6 ± 3.4, 12.8 ± 3.4, 16.6 ± 7.1 and 618 ± 82 Bq kg(-1) dry weight (DW), respectively. The (137)Cs of artificial origin was also detected in soil samples with a mean concentration of 3.8 ± 2.2 Bq kg(-1) DW. Evaluating the results, it can be concluded that the concentrations of (238)U, (226)Ra, (232)Th and (40)K in soil samples fall within the world average. Furthermore, 19 trace and major elements in groundwater samples and 22 elements in soil and plant samples were determined. The sampling locations of soil can be classified into three groups (relatively high, medium and low polluted) according to their calculated metal pollution index using the contents of trace and major elements. A cluster analysis of the contents of radioactivity and trace element contents in soil samples shows the presence of two main distinct clusters of sampling locations.

Quantification of Microbial Osmolytes in a Drought Impacted California Grassland

NASA Astrophysics Data System (ADS)

Boot, C. M.; Schaeffer, S. M.; Doyle, A. P.; Schimel, J. P.

2008-12-01

With drought frequency and severity likely increasing in the future, understanding its effect on terrestrial carbon (C) and nitrogen (N) cycling has become essential for accurately modeling ecosystem responses to climate change. Microbes respond to drought stress by accumulating internal solutes, or osmolytes, such as amino acids, betaines and polyols, to balance cell membrane water potential as the soil dries. However, when seasonal rains arrive, internal solutes are released and rapidly mineralized. We have been studying these processes in a California grassland. Beginning in summer 2007, we made monthly measurements of soil moisture, individual amino acid concentration in total soil and in microbial biomass, total dissolved organic carbon and nitrogen (DOC and DON), and microbial biomass carbon and nitrogen (MBC and MBN). We expected microbial concentrations of the known amino acid osmolytes glutamate (glu) and proline (pro) to fluctuate inversely with soil moisture. However, pro was only recovered in Mar 2008 (0.30 μg C g-1 dry soil) and the glu concentration varied proportionally with soil moisture: lowest during summer (0.06 g H2O g-1 dry soil, 2.22 μg glutamate-C g-1 dry soil) and highest in winter (0.27 g H2O g-1 dry soil, 4.43 μg glutamate-C g-1 dry soil). The trend from DOC, MBC, and DON measurements was opposite, however, with all concentrations decreasing as soil moisture shifted from dry to wet, (DOC: 64.61 to 32.49 μg C g-1 dry soil respectively). MBN was the exception to this trend, with concentrations staying nearly constant across seasons. These patterns suggest that the expected amino acids glu and pro are not being used for microbial osmoregulation in the CA grassland, and given the summer to winter decrease in MBC, the primary osmolyte source is likely to be either polyol-type compounds such as mannitol or betaines. The implications for terrestrial carbon cycle are considerable because as the frequency of drought increases, the accumulation and release of osmolytes in response to drought has potential to pump carbon out of the grassland ecosystem.

Soil aggregate and organic carbon distribution at dry land soil and paddy soil: the role of different straws returning.

PubMed

Huang, Rong; Lan, Muling; Liu, Jiang; Gao, Ming

2017-12-01

Agriculture wastes returning to soil is one of common ways to reuse crop straws in China. The returned straws are expected to improve the fertility and structural stability of soil during the degradation of straw it selves. The in situ effect of different straw (wheat, rice, maize, rape, and broad bean) applications for soil aggregate stability and soil organic carbon (SOC) distribution were studied at both dry land soil and paddy soil in this study. Wet sieving procedures were used to separate soil aggregate sizes. Aggregate stability indicators including mean weight diameter, geometric mean diameter, mean weight of specific surface area, and the fractal dimension were used to evaluate soil aggregate stability after the incubation of straws returning. Meanwhile, the variation and distribution of SOC in different-sized aggregates were further studied. Results showed that the application of straws, especially rape straw at dry land soil and rice straw at paddy soil, increased the fractions of macro-aggregate (> 0.25 mm) and micro-aggregate (0.25-0.053 mm). Suggesting the nutrients released from straw degradation promotes the growing of soil aggregates directly and indirectly. The application of different straws increased the SOC content at both soils and the SOC mainly distributed at < 0.53 mm aggregates. However, the contribution of SOC in macro- and micro-aggregates increased. Straw-applied paddy soil have a higher total SOC content but lower SOC contents at > 0.25 and 0.25-0.053 mm aggregates with dry land soil. Rape straw in dry land and rice straw in paddy field could stabilize soil aggregates and increasing SOC contents best.

Matrix effects in applying mono- and polyclonal ELISA systems to the analysis of weathered oils in contaminated soil.

PubMed

Pollard, S J T; Farmer, J G; Knight, D M; Young, P J

2002-01-01

Commercial mono- and polyclonal enzyme-linked immunosorbent assay (ELISA) systems were applied to the on-site analysis of weathered hydrocarbon-contaminated soils at a former integrated steelworks. Comparisons were made between concentrations of solvent extractable matter (SEM) determined gravimetrically by Soxhlet (dichloromethane) extraction and those estimated immunologically by ELISA determination over a concentration range of 2000-330,000 mg SEM/kg soil dry weight. Both ELISA systems tinder-reported for the more weathered soil samples. Results suggest this is due to matrix effects in the sample rather than any inherent bias in the ELISA systems and it is concluded that, for weathered hydrocarbons typical of steelworks and coke production sites, the use of ELISA requires careful consideration as a field technique. Consideration of the target analyte relative to the composition of the hydrocarbon waste encountered appears critical.

Instability improvement of the subgrade soils by lime addition at Borg El-Arab, Alexandria, Egypt

NASA Astrophysics Data System (ADS)

El Shinawi, A.

2017-06-01

Subgrade soils can affect the stability of any construction elsewhere, instability problems were found at Borg El-Arab, Alexandria, Egypt. This paper investigates geoengineering properties of lime treated subgrade soils at Borg El-Arab. Basic laboratory tests, such as water content, wet and dry density, grain size, specific gravity and Atterberg limits, were performed for twenty-five samples. Moisture-density (compaction); California Bearing Ratio (CBR) and Unconfined Compression Strength (UCS) were conducted on treated and natural soils. The measured geotechnical parameters of the treated soil shows that 6% lime is good enough to stabilize the subgrade soils. It was found that by adding lime, samples shifted to coarser side, Atterberg limits values of the treated soil samples decreased and this will improve the soil to be more stable. On the other hand, Subgrade soils improved as a result of the bonding fine particles, cemented together to form larger size and reduce the plastiCity index which increase soils strength. The environmental scanning electron microscope (ESEM) is point to the presence of innovative aggregated cement materials which reduce the porosity and increase the strength as a long-term curing. Consequently, the mixture of soil with the lime has acceptable mechanical characteristics where, it composed of a high strength base or sub-base materials and this mixture considered as subgrade soil for stabilizations and mitigation the instability problems that found at Borg Al-Arab, Egypt.

[Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

PubMed

Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

2014-08-01

The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study.

Is the Pearl River basin, China, drying or wetting? Seasonal variations, causes and implications

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Li, Jianfeng; Gu, Xihui; Shi, Peijun

2018-07-01

Soil moisture plays crucial roles in the hydrological cycle and is also a critical link between land surface and atmosphere. The Pearl River basin (PRb) is climatically subtropical and tropical and is highly sensitive to climate changes. In this study, seasonal soil moisture changes across the PRb were analyzed using the Variable Infiltration Capacity (VIC) model forced by the gridded 0.5° × 0.5° climatic observations. Seasonal changes of soil moisture in both space and time were investigated using the Mann-Kendall trend test method. Potential influencing factors behind seasonal soil moisture changes such as precipitation and temperature were identified using the Maximum Covariance Analysis (MCA) technique. The results indicated that: (1) VIC model performs well in describing changing properties of soil moisture across the PRb; (2) Distinctly different seasonal features of soil moisture can be observed. Soil moisture in spring decreased from east to west parts of the PRb. In summer however, soil moisture was higher in east and west parts but was lower in central parts of the PRb; (3) A significant drying trend was identified over the PRb in autumn, while no significant drying trends can be detected in other seasons; (4) The increase/decrease in precipitation can generally explain the wetting/drying tendency of soil moisture. However, warming temperature contributed significantly to the drying trends and these drying trends were particularly evident during autumn and winter; (5) Significant decreasing precipitation and increasing temperature combined to trigger substantially decreasing soil moisture in autumn. In winter, warming temperature is the major reason behind decreased soil moisture although precipitation is in slightly decreasing tendency. Season variations of soil moisture and related implications for hydro-meteorological processes in the subtropical and tropical river basins over the globe should arouse considerable human concerns.

A study of the dry forest communities in the Dominican Republic.

PubMed

García-Fuentes, Antonio; Torres-Cordero, Juan A; Ruiz-Valenzuela, Luis; Lendínez-Barriga, María Lucía; Quesada-Rincón, Juan; Valle-Tendero, Francisco; Veloz, Alberto; León, Yolanda M; Salazar-Mendías, Carlos

2015-03-01

This paper is a floristic and phytosociological study of the dry forest communities of the Dominican Republic. A total of 69 relevés in dry forest biotopes were carried out. The samples were subsequently subjected to Detrended Correspondence Analysis for the determination and study of possible groupings. The study does not cover tree formations growing on serpentines, nor the so-called semideciduous forests, peculiar to areas with higher rainfall. A total of nine phytocoenoses were identified. The most significant results led to the description of six new phytosociological associations: Simaroubetum berteroani (thorny dry forest on coastal dunes), Phyllostylo rhamnoidis-Prosopidetum juliflorae (southern Dominican disturbed dry forest), Consoleo moniliformis-Camerarietum linearifoliae (dry forest on hard limestones), Lemaireocereo hystricis-Prosopidetum juliflorae (northern Dominican disturbed dry forest), Lycio americani-Prosopidetum juliflorae (disturbed dry forest on saline soils) and Guettardo ellipticae-Guapiretum discoloris (dry forest on flat-topped hillocks in Montecristi). This is an important step forward in the phytosociological and floristic studies of the Caribbean territories.

Effect of aggregate structure on VOC gas adsorption onto volcanic ash soil.

PubMed

Hamamoto, Shoichiro; Seki, Katsutoshi; Miyazaki, Tsuyoshi

2009-07-15

The understanding of the gaseous adsorption process and the parameters of volatile organic compounds such as organic solvents or fuels onto soils is very important in the analysis of the transport or fate of these chemicals in soils. Batch adsorption experiments with six different treatments were conducted to determine the adsorption of isohexane, a gaseous aliphatic, onto volcanic ash soil (Tachikawa loam). The measured gas adsorption coefficient for samples of Tachikawa loam used in the first three treatments, Control, AD (aggregate destroyed), and AD-OMR (aggregate destroyed and organic matter removed), implied that the aggregate structure of volcanic ash soil as well as organic matter strongly enhanced gas adsorption under the dry condition, whereas under the wet condition, the aggregate structure played an important role in gas adsorption regardless of the insolubility of isohexane. In the gas adsorption experiments for the last three treatments, soils were sieved in different sizes of mesh and were separated into three different aggregate or particle size fractions (2.0-1.0mm, 1.0-0.5mm, and less than 0.5mm). Tachikawa loam with a larger size fraction showed higher gas adsorption coefficient, suggesting the higher contributions of macroaggregates to isohexane gas adsorption under dry and wet conditions.

Methods, quality assurance, and data for assessing atmospheric deposition of pesticides in the Central Valley of California

USGS Publications Warehouse

Zamora, Celia; Majewski, Michael S.; Foreman, William T.

2013-01-01

The U.S. Geological Survey monitored atmospheric deposition of pesticides in the Central Valley of California during two studies in 2001 and 2002–04. The 2001 study sampled wet deposition (rain) and storm-drain runoff in the Modesto, California, area during the orchard dormant-spray season to examine the contribution of pesticide concentrations to storm runoff from rainfall. In the 2002–04 study, the number and extent of collection sites in the Central Valley were increased to determine the areal distribution of organophosphate insecticides and other pesticides, and also five more sample types were collected. These were dry deposition, bulk deposition, and three sample types collected from a soil box: aqueous phase in runoff, suspended sediment in runoff, and surficial-soil samples. This report provides concentration data and describes methods and quality assurance of sample collection and laboratory analysis for pesticide compounds in all samples collected from 16 sites. Each sample was analyzed for 41 currently used pesticides and 23 pesticide degradates, including oxygen analogs (oxons) of 9 organophosphate insecticides. Analytical results are presented by sample type and study period. The median concentrations of both chloryprifos and diazinon sampled at four urban (0.067 micrograms per liter [μg/L] and 0.515 μg/L, respectively) and four agricultural sites (0.079 μg/L and 0.583 μg/L, respectively) during a January 2001 storm event in and around Modesto, Calif., were nearly identical, indicating that the overall atmospheric burden in the region appeared to be fairly similar during the sampling event. Comparisons of median concentrations in the rainfall to those in the McHenry storm-drain runoff showed that, for some compounds, rainfall contributed a substantial percentage of the concentration in the runoff; for other compounds, the concentrations in rainfall were much greater than in the runoff. For example, diazinon concentrations in rainfall were about 70 percent of the diazinon concentration in the runoff, whereas the chlorpyrifos concentration in the rain was 1.8 times greater than in the runoff. The more water-soluble pesticides—carbaryl, metolachlor, napropamide, and simazine—followed the same pattern as diazinon and had lower concentrations in rain compared to runoff. Similar to chlorpyrifos,compounds with low water solubilities and higher soil-organic carbon partition coefficients, including dacthal, pendimethalin, and trifluralin, were found to have higher concentrations in rain than in runoff water and were presumed to partition to the suspended sediments and organic matter on the ground. During the 2002–04 study period, the herbicide dacthal had the highest detection frequencies for all sample types collected from the Central Valley sites (67–100 percent). The most frequently detected compounds in the wet-deposition samples were dacthal, diazinon, chlorpyrifos, and simazine (greater than 90 percent). The median wet-deposition amounts for these compounds were 0.044 micrograms per square meter per day (μg/m2/day), 0.209 μg/m2/day, 0.079 μg/m2/day, and 0.172 μg/m2/day, respectively. For the dry-deposition samples, detection frequencies were greater than 73 percent for the compounds dacthal, metolachor, and chlorpyrifos, and median deposition amounts were an order of magnitude less than for wet deposition. The differences between wet deposition and dry deposition appeared to be closely related to the Henry’s Law (H) constant of each compound, although the mass deposited by dry deposition takes place over a much longer time frame. Pesticides detected in rainfall usually were detected in the aqueous phase of the soil-box runoff water, and the runoff concentrations were generally similar to those in the rainfall. For compounds detected in the aqueous phase and suspended-sediment samples of soil-box runoff, concentrations of pesticides in the aqueous phase generally were detected in low concentrations and had few corresponding detections in the suspended- sediment samples. Dacthal, diazinon, chlorpyrifos, and simazine were the most frequently detected pesticides (greater than 83 percent) in the aqueous-phase samples, with median concentrations of 0.010 μg/L, 0.045 μg/L, 0.016 μg/L, and 0.077 μg/L, respectively. Simazine was the most frequently detected compound in the suspended-sediment samples (69 percent), with a median concentration of 0.232 μg/L. Results for compounds detected in the surficial-soil samples collected throughout the study period showed that there was an increase in concentration for some compounds, indicating atmospheric deposition of these compounds onto the soil-box surface. In the San Joaquin Valley, the compounds chlorpyrifos, dacthal, and iprodione were detected at higher concentrations (between 1.4 and 2 times greater) than were found in the background samples collected from the San Joaquin Valley soil-box sites. In the Sacramento Valley, the compounds chlorpyrifos, dacthal, iprodione, parathionmethyl, and its oxygen analog, paraoxon-methyl, were detected in samples collected during the study period in low concentrations, but were not detected in the background concentration of the Sacramento Valley soil mix.

Assessing five evolving microbial enzyme models against field measurements from a semiarid savannah—What are the mechanisms of soil respiration pulses?

NASA Astrophysics Data System (ADS)

Zhang, Xia; Niu, Guo-Yue; Elshall, Ahmed S.; Ye, Ming; Barron-Gafford, Greg A.; Pavao-Zuckerman, Mitch

2014-09-01

Soil microbial respiration pulses in response to episodic rainfall pulses (the "Birch effect") are poorly understood. We developed and assessed five evolving microbial enzyme models against field measurements from a semiarid savannah characterized by pulsed precipitation to understand the mechanisms to generate the Birch pulses. The five models evolve from an existing four-carbon (C) pool model to models with additional C pools and explicit representations of soil moisture controls on C degradation and microbial uptake rates. Assessing the models using techniques of model selection and model averaging suggests that models with additional C pools for accumulation of degraded C in the dry zone of the soil pore space result in a higher probability of reproducing the observed Birch pulses. Degraded C accumulated in dry soil pores during dry periods becomes immediately accessible to microbes in response to rainstorms, providing a major mechanism to generate respiration pulses. Explicitly representing the transition of degraded C and enzymes between dry and wet soil pores in response to soil moisture changes and soil moisture controls on C degradation and microbial uptake rates improve the models' efficiency and robustness in simulating the Birch effect. Assuming that enzymes in the dry soil pores facilitate degradation of complex C during dry periods (though at a lower rate) results in a greater accumulation of degraded C and thus further improves the models' performance. However, the actual mechanism inducing the greater accumulation of labile C needs further experimental studies.

Impact of drainage on wettability of fen peat-moorsh soils

NASA Astrophysics Data System (ADS)

Szajdak, L.; Szatyłowicz, J.; Brandyk, T.

2009-04-01

High water retention in peat is attributed to structural voids (macro-pores) due to the partial degradation of the structure of peat-forming plants, and molecular absorption sites (micro-pores) associated with the formation of humic substances. Water retention by the heterogeneously-structured system in peat organic matter depends on the chemical structure of solid surfaces. These naturally wet solids, if dried sufficiently, lose the ability to rewet quickly when immersed in water. The ability of peat surfaces to attract and hold water is attributed to hydrophilic functional groups which characterize the organic substances of peat. The investigations of chemical and physical properties were performed for three different peat-moorsh soils located in the Biebrza River Valley in Poland. All examined soils were used as meadow. Soil samples were taken from two depths: 5-10 cm (moorsh) and 50-80 cm (peat). Total organic carbon (TOC), dissolved organic carbon (DOC) and humic acids (HA) extracted from these samples were analysed. Also basic physical properties such as ash content and bulk density were measured. Wetting behavior of soils was quantified using water drop penetration time test (WDPT) and measured values of the soil-water contact angle using sessile drop method. The measurements were conducted on air-dry soil samples which volumetric moisture content was not exceeding 7%. The significant differences in the concentrations of TOC, DOC and properties of HA between two investigated depth of among peat and moorsh samples were observed. The measured concentrations of total organic carbon in the considered soils ranged from 37.2 to 45.6%. Generally, the decrease of total organic carbon concentration with depth of profiles was observed. The contents of dissolved organic carbon in the soils ranged from 5.3 to 19.4%. The quantities of dissolved organic carbon decreased simultaneously with E4/E6 values and with the depth of the soil profiles. For the investigated peat's, an increase of the depth is accompanied by the decrease in the degree of humification or an increase in chemical maturity of HA. The measured values of the contact angle for investigated soils were in the range from 81.4˚ to 114.3˚ what indicates their high water repellency. The WDPT was positively correlated with total organic carbon, organic matter and humic acids content while ash content, soil bulk density, pH and absorbance were correlated negatively. The highest value of correlation coefficient (statistically significant) was obtained for relation between WDPT and ash content. The soil water contact angle was less correlated with peat-moorsh soil properties in comparison with WDPT with one exception pH. The pH against the contact angle indicates tendency of increasing the contact angle with decreasing pH.

Influence of nano-material on the expansive and shrinkage soil behavior

NASA Astrophysics Data System (ADS)

Taha, Mohd Raihan; Taha, Omer Muhie Eldeen

2012-10-01

This paper presents an experimental study performed on four types of soils mixed with three types of nano-material of different percentages. The expansion and shrinkage tests were conducted to investigate the effect of three type of nano-materials (nano-clay, nano-alumina, and nano-copper) additive on repressing strains in compacted residual soil mixed with different ratios of bentonite (S1 = 0 % bentonite, S2 = 5 % bentonite, S3 = 10 % bentonite, and S4 = 20 % bentonite). The soil specimens were compacted under the condition of maximum dry unit weight and optimum water content ( w opt) using standard compaction test. The physical and mechanical results of the treated samples were determined. The untreated soil values were used as control points for comparison purposes. It was found that with the addition of optimum percentage of nano-material, both the swell strain and shrinkage strain reduced. The results show that nano-material decreases the development of desiccation cracks on the surface of compacted samples without decrease in the hydraulic conductivity.

Soil microbial communities and enzyme activities in sea-buckthorn (Hippophae rhamnoides) plantation at different ages.

PubMed

Yang, Miao; Yang, Dan; Yu, Xuan

2018-01-01

The aim of this study was to assess the impact of forest age and season on the soil microbial community and enzyme activities in sea-buckthorn plantation system and to determine the relative contributions to soil microbial properties. Soil sampling was carried out in the dry season (April) and wet season (September) in four areas, including: abandoned farmland (NH), an 8-year- old plantation (young plantation, 8Y), a 13-year-old plantation (middle-aged plantation, 13Y), and an 18-year-old plantation (mature plantation, 18Y). The results showed that forest age and season have a significant effect on soil microbial community structure and enzyme activities. The total, bacterial, fungal, Gram-negative (G+), and Gram-positive (G-) PLFAs increased gradually with forest age, with the highest values detected in 18Y. All the detected enzyme activities showed the trend as a consequence of forest age. The microbial PLFAs and soil enzyme activities were higher in the wet season than the dry season. However, there were no significant interactions between forest age and season. A Correlation analysis suggested that soil microbial communities and enzyme activities were significantly and positively correlated with pH, total nitrogen (TN) and available phosphorus (AP). Season had a stronger influence on soil microbial communities than forest age. In general, sea-buckthorn plantations establishment might be a potential tool for maintaining and increasing soil fertility in arid and semi-arid regions.

Soil microbial communities and enzyme activities in sea-buckthorn (Hippophae rhamnoides) plantation at different ages

PubMed Central

Yang, Miao; Yang, Dan

2018-01-01

The aim of this study was to assess the impact of forest age and season on the soil microbial community and enzyme activities in sea-buckthorn plantation system and to determine the relative contributions to soil microbial properties. Soil sampling was carried out in the dry season (April) and wet season (September) in four areas, including: abandoned farmland (NH), an 8-year- old plantation (young plantation, 8Y), a 13-year-old plantation (middle-aged plantation, 13Y), and an 18-year-old plantation (mature plantation, 18Y). The results showed that forest age and season have a significant effect on soil microbial community structure and enzyme activities. The total, bacterial, fungal, Gram-negative (G+), and Gram-positive (G-) PLFAs increased gradually with forest age, with the highest values detected in 18Y. All the detected enzyme activities showed the trend as a consequence of forest age. The microbial PLFAs and soil enzyme activities were higher in the wet season than the dry season. However, there were no significant interactions between forest age and season. A Correlation analysis suggested that soil microbial communities and enzyme activities were significantly and positively correlated with pH, total nitrogen (TN) and available phosphorus (AP). Season had a stronger influence on soil microbial communities than forest age. In general, sea-buckthorn plantations establishment might be a potential tool for maintaining and increasing soil fertility in arid and semi-arid regions. PMID:29324845

Isotope fractionation of sandy-soil water during evaporation - an experimental study.

PubMed

Rao, Wen-Bo; Han, Liang-Feng; Tan, Hong-Bing; Wang, Shuai

2017-06-01

Soil samples containing water with known stable isotopic compositions were prepared. The soil water was recovered by using vacuum/heat distillation. The experiments were held under different conditions to control rates of water evaporation and water recovery. Recoveries, δ 18 O and δ 2 H values of the soil water were determined. Analyses of the data using a Rayleigh distillation model indicate that under the experimental conditions only loosely bound water is extractable in cases where the recovery is smaller than 100 %. Due to isotopic exchange between vapour and remaining water in the micro channels or capillaries of the soil matrix, isotopic fractionation may take place under near-equilibrium conditions. This causes the observed relationship between δ 2 H and δ 18 O of the extracted water samples to have a slope close to 8. The results of this study may indicate that, in arid zones when soil that initially contains water dries out, the slope of the relationship between δ 2 H and δ 18 O values should be close to 8. Thus, a smaller slope, as observed by some groundwater and soil water samples in arid zones, may be caused by evaporation of water before the water has entered the unsaturated zone.

Mass flow of a volatile organic liquid mixture in soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerstl, Z.; Galin, Ts.; Yaron, B.

1994-05-01

The flow of kerosene, a volatile organic liquid mixture (VOLM), was studied in loam and clay soils and in a medium sand. The kerosene residual capacity and conductivity were determined for all three media at different initial moisture contents and with kerosene of different compositions. The kerosene conductivity of the soil was found to be strongly influenced by the soil texture and initial moisture content as well as by the kerosene composition. The kerosene conductivity of the sand was two orders of magnitude greater than that of the soils and was unaffected by initial moisture contents as high as fieldmore » capacity. The kerosene conductivity of the loam soil was similar in oven dry and air dry soils, but increased significantly in soils at 70% and fun field capacity due to the Yuster effect. In the clay soil the kerosene conductivity of the air dry sod was four times that of the oven dry sod and increased somewhat in the soil at 70% field capacity. No kerosene flow was observed in the oven dry soil at full field capacity. The differences in kerosene conductivity in these soils and the effect of moisture content were attributed to the different pore-sin distributions of the soil& Changes in the composition of the kerosene due to volatilization of the light fractions resulted in increased viscosity of the residual kerosene. This increased viscosity affected the fluid properties of kerosene, which resulted in decreased kerosene conductivity in the sand and the soils. 29 refs., 4 figs., 4 tabs.« less

Determination of low methylmercury concentrations in peat soil samples by isotope dilution GC-ICP-MS using distillation and solvent extraction methods.

PubMed

Pietilä, Heidi; Perämäki, Paavo; Piispanen, Juha; Starr, Mike; Nieminen, Tiina; Kantola, Marjatta; Ukonmaanaho, Liisa

2015-04-01

Most often, only total mercury concentrations in soil samples are determined in environmental studies. However, the determination of extremely toxic methylmercury (MeHg) in addition to the total mercury is critical to understand the biogeochemistry of mercury in the environment. In this study, N2-assisted distillation and acidic KBr/CuSO4 solvent extraction methods were applied to isolate MeHg from wet peat soil samples collected from boreal forest catchments. Determination of MeHg was performed using a purge and trap GC-ICP-MS technique with a species-specific isotope dilution quantification. Distillation is known to be more prone to artificial MeHg formation compared to solvent extraction which may result in the erroneous MeHg results, especially with samples containing high amounts of inorganic mercury. However, methylation of inorganic mercury during the distillation step had no effect on the reliability of the final MeHg results when natural peat soil samples were distilled. MeHg concentrations determined in peat soil samples after distillation were compared to those determined after the solvent extraction method. MeHg concentrations in peat soil samples varied from 0.8 to 18 μg kg(-1) (dry weight) and the results obtained with the two different methods did not differ significantly (p=0.05). The distillation method with an isotope dilution GC-ICP-MS was shown to be a reliable method for the determination of low MeHg concentrations in unpolluted soil samples. Furthermore, the distillation method is solvent-free and less time-consuming and labor-intensive when compared to the solvent extraction method. Copyright © 2014 Elsevier Ltd. All rights reserved.

Soil moisture determination study. [Guymon, Oklahoma

NASA Technical Reports Server (NTRS)

Blanchard, B. J.

1979-01-01

Soil moisture data collected in conjunction with aircraft sensor and SEASAT SAR data taken near Guymon, Oklahoma are summarized. In order to minimize the effects of vegetation and roughness three bare and uniformly smooth fields were sampled 6 times at three day intervals on the flight days from August 2 through 17. Two fields remained unirrigated and dry. A similar pair of fields was irrigated at different times during the sample period. In addition, eighteen other fields were sampled on the nonflight days with no field being sampled more than 24 hours from a flight time. The aircraft sensors used included either black and white or color infrared photography, L and C band passive microwave radiometers, the 13.3, 4.75, 1.6 and .4 GHz scatterometers, the 11 channel modular microwave scanner, and the PRT5.

Drought and Winter Drying (Pest Alert)

Treesearch

USDA Forest Service

Drought and winter drying have periodically caused major damage to trees. Drought reduces the amount of water available in the soil. In the case of winter drying, the water may be in the soil, but freezing of the soil makes the water unavailable to the tree. In both cases, more water is lost through transpiration than is available to the plant. Symptoms of drought and...

Trace element analysis of soil type collected from the Manjung and central Perak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azman, Muhammad Azfar, E-mail: m-azfar@nuclearmalaysia.gov.my; Hamzah, Suhaimi; Rahman, Shamsiah Abdul

2015-04-29

Trace elements in soils primarily originated from their parent materials. Parents’ material is the underlying geological material that has been undergone different types of chemical weathering and leaching processes. Soil trace elements concentrations may be increases as a result of continuous input from various human activities, including power generation, agriculture, mining and manufacturing. This paper describes the Neutron Activation Analysis (NAA) method used for the determination of trace elements concentrations in part per million (ppm) present in the terrestrial environment soil in Perak. The data may indicate any contamination of trace elements contributed from human activities in the area. Themore » enrichment factors were used to check if there any contamination due to the human activities (power plants, agricultural, mining, etc.) otherwise the values would serve as a baseline data for future study. The samples were collected from 27 locations of different soil series in the area at two different depths: the top soil (0-15cm) and the sub soil (15-30cm). The collected soil samples were air dried at 60°C and passed through 2 µm sieve. Instrumental Neutron Activation Analysis (NAA) has been used for the determination of trace elements. Samples were activated in the Nuclear Malaysia TRIGA Mark II reactor followed by gamma spectrometric analysis. By activating the stable elements in the samples, the elements can be determined from the intensities of gamma energies emitted by the respected radionuclides.« less

Scale-dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical dry forests.

PubMed

Waring, Bonnie G; Adams, Rachel; Branco, Sara; Powers, Jennifer S

2016-01-01

Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Soil moisture-soil temperature interrelationships on a sandy-loam soil exposed to full sunlight

Treesearch

David A. Marquis

1967-01-01

In a study of birch regeneration in New Hampshire, soil moisture and temperature were found to be intimately related. Not only does low moisture lead to high temperature, but high temperature undoubtedly accelerates soil drying, setting up a vicious cycle of heating and drying that may prevent seed germination or kill seedlings.

Resuspension of soil as a source of airborne lead near industrial facilities and highways.

PubMed

Young, Thomas M; Heeraman, Deo A; Sirin, Gorkem; Ashbaugh, Lowell L

2002-06-01

Geologic materials are an important source of airborne particulate matter less than 10 microm aerodynamic diameter (PM10), but the contribution of contaminated soil to concentrations of Pb and other trace elements in air has not been documented. To examine the potential significance of this mechanism, surface soil samples with a range of bulk soil Pb concentrations were obtained near five industrial facilities and along roadsides and were resuspended in a specially designed laboratory chamber. The concentration of Pb and other trace elements was measured in the bulk soil, in soil size fractions, and in PM10 generated during resuspension of soils and fractions. Average yields of PM10 from dry soils ranged from 0.169 to 0.869 mg of PM10/g of soil. Yields declined approximately linearly with increasing geometric mean particle size of the bulk soil. The resulting PM10 had average Pb concentrations as high as 2283 mg/kg for samples from a secondary Pb smelter. Pb was enriched in PM10 by 5.36-88.7 times as compared with uncontaminated California soils. Total production of PM10 bound Pb from the soil samples varied between 0.012 and 1.2 mg of Pb/kg of bulk soil. During a relatively large erosion event, a contaminated site might contribute approximately 300 ng/m3 of PM10-bound Pb to air. Contribution of soil from contaminated sites to airborne element balances thus deserves consideration when constructing receptor models for source apportionment or attempting to control airborne Pb emissions.

Magnetic Grain-size Proxies in Loessic Soils and Their Potential use in Paleorainfall Reconstruction

NASA Astrophysics Data System (ADS)

Machac, T. A.; Geiss, C. E.; Zanner, C. W.

2005-05-01

As part of our ongoing rock-magnetic study of loessic soil profiles we sampled over 70 in Nebraska, Iowa, Missouri and Illinois. Our sampling sites are located in stable upland positions and extend along a rainfall gradient which ranges from an average annual precipitation of less than 500 mm/year in southwestern Nebraska to almost 1000 mm/year in central Missouri. Soil cores were obtained with the aid of a hydraulic soil probe, described and subsampled into small plastic bags. Samples were air-dried in the laboratory and the < 2mm fraction was used for magnetic analyses. We measured magnetic susceptibility X and several remanence parameters (ARM, IRM) for all samples. Hysteresis measurements, IRM acquisition curves and time dependence of IRM acquisition were measured for a subset of samples. All samples show magnetically enhanced A- and B-horizons, which results in increased values of X, ARM and IRM. Changes in the ratio of ARM/IRM suggest an increase in the relative abundance of stable single domain (SSD) particles. VRM analyses show that the upper soil horizons are enhanced in ultrafine superparamagnetic (SP) ferrimagnets as well. Changes in the relative abundance of SP and SSD ferrimagnets along our transsect correlates well with the modern precipitation gradient, suggesting the use of grain-size dependent magnetic parameter as a potential paleorainfall proxy when analyzing paleosols.

Lanthanum toxicity to five different species of soil invertebrates in relation to availability in soil.

PubMed

Li, Jinxia; Verweij, Rudo A; van Gestel, Cornelis A M

2018-02-01

This study determined the toxicity of lanthanum, one of the most commonly used rare earth elements (REEs), to five representative soil invertebrates after 3-4 weeks exposure. Toxicity was related to total, 0.01 M CaCl 2 -extractable and porewater concentrations in the standard LUFA 2.2 soil, and for earthworms also to body concentrations. La sorption to LUFA 2.2 soil, estimated by relating total soil concentrations to CaCl 2 -extractable or porewater concentrations seemed to reach saturation at >1000 mg La/kg dry soil. Isopod (Porcellio scaber) growth was the most sensitive endpoint, followed by earthworm (Eisenia andrei), enchytraeid (Enchytraeus crypticus), springtail (Folsomia candida) and oribatid mite (Oppia nitens) reproduction, with EC 50 s of 312 (95% confidence interval: 5.6-619), 529 (295-762), 1010 ((>377 < 3133), 1220 (1180-1250) and 1500 (1250-1750) mg La/kg dry soil, respectively. EC 50 s related to CaCl 2 -extractable concentrations ranged between 1.3 (0.046-2.6) and 15.6 (5.6-25.7) mg La/kg dry soil, while porewater-based EC 50 s were 3.5 (-) and 10.2 (-) mg/L for the springtails and mites, respectively. La uptake in the earthworms linearly increased with increasing exposure concentration with bioaccumulation factors ranging between 0.04 and 0.53 (average ± SE: 0.24 ± 0.032). EC 50 for effects on earthworm reproduction related to internal concentrations was 184 (61-301) mg La/kg dry body weight. A risk assessment based on the available toxicity for soil invertebrates, bacteria and plants resulted in an HC 5 of approx. 50 mg La/kg dry soil, suggesting that La may affect soil ecosystems at concentrations slightly above natural background levels (6.6-50 mg La/kg dry soil) in non-polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of water table variations and input of natural organic matter on the cycles of C and N, and mobility of As, Zn and Cu from a soil impacted by the burning of chemical warfare agents: A mesocosm study.

PubMed

Thouin, Hugues; Battaglia-Brunet, Fabienne; Gautret, Pascale; Le Forestier, Lydie; Breeze, Dominique; Séby, Fabienne; Norini, Marie-Paule; Dupraz, Sebastien

2017-10-01

A mesocosm study was conducted to assess the impact of water saturation episodes and of the input of bioavailable organic matter on the biogeochemical cycles of C and N, and on the behavior of metal(loid)s in a soil highly contaminated by the destruction of arsenical shells. An instrumented mesocosm was filled with contaminated soil taken from the "Place-à-Gaz" site. Four cycles of dry and wet periods of about one month were simulated for 276days. After two dry/wet cycles, organic litter sampled on the site was added above the topsoil. The nitrogen cycle was the most impacted by the wet/dry cycles, as evidenced by a denitrification microbial process in the saturated level. The concentrations of the two most mobile pollutants, Zn and As, in the soil water and in the mesocosm leachate were, respectively, in the 0.3-1.6mM and 20-110μM ranges. After 8months of experiment, about 83g·m -3 of Zn and 3.5g·m -3 of As were leached from the soil. These important quantities represent <1% of the solid stock of this contaminant. Dry/wet cycles had no major effect on Zn mobility. However, soil saturation induced the immobilization of As by trapping As V but enhanced As III mobility. These phenomena were amplified by the presence of bioavailable organic matter. The study showed that the natural deposition of forest organic litter allowed a part of the soil's biological function to be restored but did not immobilize all the Zn and As, and even contributed to transport of As III to the surrounding environment. The main hazard of this type of site, contaminated by organo-arsenic chemical weapons, is the constitution of a stock of As that may leach into the surrounding environment for several hundred years. Copyright © 2017 Elsevier B.V. All rights reserved.

Evidence of hydraulic lift for pre-rainy season leaf out and dry-season stem water enrichment in Sclerocarya birrea, a tropical agroforestry tree

NASA Astrophysics Data System (ADS)

Ceperley, Natalie; Mande, Theophile; Rinaldo, Andrea; Parlange, Marc B.

2014-05-01

We use stable isotopes of water as tracers to follow water use by five Sclerocarya birrea trees in a catchment in South Eastern Burkina Faso interspersed with millet fields, gallery forest, Sudanian savanna, and fallow fields. Isotopic ratios were determined from water extracted from stems of the trees and sub-canopy soil of two of them, while nearby ground water, precipitation, and surface water was sampled weekly. A unique configuration of sensors connected with a wireless sensor network of meteorological stations measured sub-canopy shading, the temperature and humidity in the canopy, through-fall, and soil moisture under two of the trees. Both water extracted from sap and water extracted from soil is extremely enriched in the dry season, but drop to levels close to the ground water in February or March, which coincides with the growth of leaves. Dates of leaf out were confirmed by changes in δDH and δO18 concentrations of water, photographic documentation & pixel analysis, and analysis of sub-canopy radiation and proceeded the rise in humidity and flow that was later detected in the sub-canopy soil, the trunk of the tree (sap-flow), and atmosphere (canopy VPD). Examination of the isotopic signature suggests that size of tree plays an important role in duration and timing of this leaf-out as well as the degree of enrichment during the peak of the dry season. Further examination of the isotopic signatures of the roots suggested that the trees are performing hydraulic redistribution, or lifting the ground water and "sharing it" with the soil in the rooting zone in the dry season. The enriched level of xylem in this case is a product of water loss, and enrichment, along the travel path of the water from the roots to the tip of the stem, as evidenced by the variation according to size of tree. Vapor pressure deficit, soil water, and soil moisture interactions support this picture of interacting controls, separate from hydrologic triggers on the water movement in the tree.

Ammonia Volatilization from Urea-Application Influenced Germination and Early Seedling Growth of Dry Direct-Seeded Rice

PubMed Central

Qi, Xiaoli; Wu, Wei; Shah, Farooq; Peng, Shaobing; Huang, Jianliang; Cui, Kehui; Liu, Hongyan; Nie, Lixiao

2012-01-01

Poor seed germination and early seedling growth associated with urea-induced soil ammonia volatilization are major constraints in the adoption of dry direct-seeded rice. To directly examine soil ammonia volatilization and its damage to seed germination and early seedling growth of dry direct-seeded rice when urea is applied at seeding, two Petri-dish incubation experiments and a field experiment were conducted. Ammonia volatilization due to urea application significantly reduced seed germination and early seedling growth of dry direct-seedling rice. NBPT significantly reduced ammonia volatilization following urea application. The application of ammonium sulfate, instead of urea at seeding, may mitigate poor crop establishment of dry direct-seeded rice. Root growth of dry direct-seeded rice was more seriously inhibited by soil ammonia volatilization than that of shoot. Results suggest that roots are more sensitive to soil ammonia toxicity than shoots in dry direct-seeded rice system when N is applied as urea at seeding. PMID:22454611

Biological Invasion Influences the Outcome of Plant-Soil Feedback in the Invasive Plant Species from the Brazilian Semi-arid.

PubMed

de Souza, Tancredo Augusto Feitosa; de Andrade, Leonaldo Alves; Freitas, Helena; da Silva Sandim, Aline

2017-05-30

Plant-soil feedback is recognized as the mutual interaction between plants and soil microorganisms, but its role on the biological invasion of the Brazilian tropical seasonal dry forest by invasive plants still remains unclear. Here, we analyzed and compared the arbuscular mycorrhizal fungi (AMF) communities and soil characteristics from the root zone of invasive and native plants, and tested how these AMF communities affect the development of four invasive plant species (Cryptostegia madagascariensis, Parkinsonia aculeata, Prosopis juliflora, and Sesbania virgata). Our field sampling revealed that AMF diversity and frequency of the Order Diversisporales were positively correlated with the root zone of the native plants, whereas AMF dominance and frequency of the Order Glomerales were positively correlated with the root zone of invasive plants. We grew the invasive plants in soil inoculated with AMF species from the root zone of invasive (I changed ) and native (I unaltered ) plant species. We also performed a third treatment with sterilized soil inoculum (control). We examined the effects of these three AMF inoculums on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas. We found that I unaltered and I changed promoted the growth of all invasive plants and led to a higher plant dry biomass, mycorrhizal colonization, and P uptake than control, but I changed showed better results on these variables than I unaltered . For plant responsiveness to mycorrhizas and fungal inoculum effect on plant P concentration, we found positive feedback between changed-AMF community (I changed ) and three of the studied invasive plants: C. madagascariensis, P. aculeata, and S. virgata.

The characterization, mobility, and persistence of roaster-derived arsenic in soils at Giant Mine, NWT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bromstad, Mackenzie J.; Wrye, Lori A.; Jamieson, Heather E.

Approximately 20,000 tonnes of arsenic (As)-bearing emissions from roasting gold (Au)-bearing arsenopyrite ore were aerially released from 1949 to 1999 at Giant Mine, near Yellowknife, Canada. Soil samples collected within 4 km of the former roaster from sites undisturbed by mining or other human activity contain up to 7700 mg/kg total As. Total As concentrations are highest within a few cm of the surface, and particularly enriched in soil pockets on rock outcrops. Scanning electron microscopy and synchrotron microanalysis show that roaster-derived arsenic trioxide (As2O3) has persisted in shallow soils in the area. Roaster-generated maghemite and hematite are also present.more » These anthropogenic forms of As are much more common in near-surface soils than natural As-bearing minerals. Comparison of the proportions of As, Sb, and Au concentrations in outcrop soil samples and historic As2O3-rich dust captured by emission controls suggest most of the roaster-derived As in soils at Giant was likely deposited before 1964. Topographic restriction by rock outcrops and a dry, cold climate likely contribute to the persistence of As2O3 in outcrop soils.« less

Occurrence and source apportionment of polycyclic aromatic hydrocarbons in soils and sediment from Hanfeng Lake, Three Gorges, China.

PubMed

Cai, Jing; Gao, Shutao; Zhu, Like; Jia, Xuwei; Zeng, Xiangying; Yu, Zhiqiang

2017-11-10

This study was conducted to investigate the pollutant status and the retention mechanism of polycyclic aromatic hydrocarbons (PAHs) in soils and sediment from bank-water-level-fluctuating zone (WLFZ)-water systems in Hanfeng Lake, Three Gorges, China. The concentrations of the 16 PAHs ranged from 21.8 to 1324 ng g -1 dry wt for all 20 soil and sediment samples. These concentration levels were remarkably lower than those in soils and sediment collected domestically and worldwide. PAHs with two and three rings were found to be dominant in all the samples, with phenanthrene being most abundant. The spatial distribution of PAHs in bank soil, WLFZ soil, and sediment implied that the transfer and fate of PAHs in the bank soil-WLFZ soil-sediment systems were influenced by both water dynamic factors and physicochemical properties of PAHs. Diagnostic ratio analysis and principal component analysis suggested that the PAHs in the areas of Hanfeng Lake were primarily (>75%) derived from coal combustion and vehicle emissions . Use of natural gas, improving gasoline/diesel quality and phasing out old and nonstandard vehicles and ships are proposed to control PAH contamination and protect drinking water safety in the region.

Linear Regression between CIE-Lab Color Parameters and Organic Matter in Soils of Tea Plantations

NASA Astrophysics Data System (ADS)

Chen, Yonggen; Zhang, Min; Fan, Dongmei; Fan, Kai; Wang, Xiaochang

2018-02-01

To quantify the relationship between the soil organic matter and color parameters using the CIE-Lab system, 62 soil samples (0-10 cm, Ferralic Acrisols) from tea plantations were collected from southern China. After air-drying and sieving, numerical color information and reflectance spectra of soil samples were measured under laboratory conditions using an UltraScan VIS (HunterLab) spectrophotometer equipped with CIE-Lab color models. We found that soil total organic carbon (TOC) and nitrogen (TN) contents were negatively correlated with the L* value (lightness) ( r = -0.84 and -0.80, respectively), a* value (correlation coefficient r = -0.51 and -0.46, respectively) and b* value ( r = -0.76 and -0.70, respectively). There were also linear regressions between TOC and TN contents with the L* value and b* value. Results showed that color parameters from a spectrophotometer equipped with CIE-Lab color models can predict TOC contents well for soils in tea plantations. The linear regression model between color values and soil organic carbon contents showed it can be used as a rapid, cost-effective method to evaluate content of soil organic matter in Chinese tea plantations.

Degradation of Biochemical Activity in Soil Sterilized by Dry Heat and Gamma Radiation

NASA Technical Reports Server (NTRS)

Shih, K. L.; Souza, K. A.

1978-01-01

The effect of soil sterilization by dry heat (0.08% relative humidity), gamma radiation, or both on soil phosphatase, urease, and decarboxylase activity was studied. Soil sterilized by a long exposure to dry heat at relatively low temperatures (eight weeks at 100.5 C) retained higher activities than did soil exposed to a higher temperature (two weeks at 124.5 C), while all activity was destroyed by four days at 148.5 C. Sterilization with 7.5 Mrads destroyed less activity than did heat sterilization. The effect of several individually nonsterizing doses of heat radiation is described.

Landscapes to riverscapes: bridging the gap between research and conservation of stream fishes

USGS Publications Warehouse

Fausch, Kurt D.; Torgersen, Christian E.; Baxter, Colden V.; Li, Hiram W.

2002-01-01

Woodcock (Philohela minor), earthworms, and soil samples were collected from January-March 1965, from fields in southeastern Louisiana approximately 3 years after discontinuance of areal treatments with heptachlor in this region. Heptachlor epoxide residues in woodcock averaged 0.42 ppm (dry weight), conspicuously lower than in 1961 and 1962. Residues of DDE in woodcock averaged 3.62 pprn, higher than in birds taken in the same area in 1961-62. Earthworms and soils contained traces of several organochlorine pesticides.

Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

NASA Astrophysics Data System (ADS)

Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro

2016-04-01

Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected as much as collected in flask. Stream water and groundwater samples were collected for 40 L each. All the water samples were filtered through 0.45 μm pore-size membrane. Water samples with less than few L were concentrated by evaporative concentration. Water samples with more than 40 L were concentrated using the ammonium molybdophosphate (AMP)/Cs compound method. The Cs-137 concentration was determined using gamma-ray spectrometry with a germanium semiconductor detector. Spatial distribution of dissolved Cs-137 concentration in the slope was obtained and the source of Cs-137 concentration in stream water was examined. The Cs-137 concentration in groundwater showed low value of 0.0004-0.001 Bq/L. The Cs-137 concentration of soil water showed 0.01-0.1 Bq/L. And Cs-137 concentrations of stream water were 0.007-0.03 Bq/L at steady state condition. Also Cs-137 concentrations in stream water showed temporary increase during rainfall event. The source of dissolved Cs-137 was suggested to be shallow soil water under saturated condition or leaching from the litter might be affecting.

Rapid drying soils with microwave ovens.

DOT National Transportation Integrated Search

2002-07-01

Soils are normally dried in either a convection oven or stove. Inspections of field and laboratory moisture content testing indicated that the typical drying durations for a convection oven and stove were, 24 hours and 60 minutes, respectively. The o...

Thermal diffusivity of peat, sand and their mixtures at different water contents

NASA Astrophysics Data System (ADS)

Gvozdkova, Anna; Arkhangelskaya, Tatiana

2014-05-01

Thermal diffusivity of peat, sand and their mixtures at different water contents was studied using the unsteady-state method described in (Parikh et al., 1979). Volume sand content in studied samples was 0 % (pure peat), 5, 10, 15, 20, 30, 40, 50, 55 and 62 % (pure sand). Thermal diffusivity of air-dry samples varied from 0.6×10-7m2s-1 for pure peat to 7.0×10-7m2s-1 for pure sand. Adding 5 and 10 vol. % of sand didn't change the thermal diffusivity of studied mixture as compared with that of the pure air-dry peat. Adding 15 % of sand resulted in significant increase of thermal diffusivity by approximately 1.5 times: from 0.6×10-7m2s-1 to 0.9×10-7m2s-1. It means that small amounts of sand with separate sand particles distributed within the peat don't contribute much to the heat transfer through the studied media. And there is a kind of threshold between the 10 and 15 vol. % of sand, after which the continuous sandy chains are formed within the peat, which can serve as preferential paths of heat transport. Adding 20 and 30 % of sand resulted in further increase of thermal diffusivity to 1.3×10-7m2s-1 and 1.7×10-7m2s-1, which is more than two and three times greater than the initial value for pure peat. Thermal diffusivity vs. moisture content dependencies had different shapes. For sand contents of 0 to 40 vol. % the thermal diffusivity increased with water content in the whole studied range from air-dry samples to the capillary moistened ones. For pure peat the experimental curves were almost linear; the more sand was added the more pronounced became the S-shape of the curves. For sand contents of 50 % and more the curves had a pronounced maximum within the range of water contents between 0.10 and 0.25 m3m-3 and then decreased. The experimental k(θ) curves, where k is soil thermal diffusivity, θ is water content, were parameterized with a 4-parameter approximating function (Arkhangelskaya, 2009, 2014). The suggested approximation has an advantage of clear physical interpretation: the parameters are (1) the thermal diffusivity of the dry sample; (2) the difference between the highest thermal diffusivity at some optional water content and that of the dry sample; (3) the optional water content at which the thermal diffusivity reaches its maximum; (4) half-width of the peak of the k(θ) curve. The increase of sand contents in studied mixtures was accompanied by the increase of the parameters (1), (2) and (4) and the decrease of the parameter (3). References Parikh R.J., Havens J.A., Scott H.D., 1979. Thermal diffusivity and conductivity of moist porous media. Soil Science Society of America Journal 43, 1050-1052. Arkhangel'skaya T.A., 2009. Parameterization and mathematical modeling of the dependence of soil thermal diffusivity on the water content. Eurasian Soil Science 42 (2), 162-172. doi: 10.1134/S1064229309020070 Arkhangelskaya T.A., 2014. Diversity of thermal conditions within the paleocryogenic soil complexes of the East European Plain: The discussion of key factors and mathematical modeling // Geoderma. Vol. 213. P. 608-616. doi 10.1016/j.geoderma.2013.04.001

The Impact of Multiple Freeze-Thaw Cycles on the Microstructure of Aggregates from a Soddy-Podzolic Soil: A Microtomographic Analysis

NASA Astrophysics Data System (ADS)

Skvortsova, E. B.; Shein, E. V.; Abrosimov, K. N.; Romanenko, K. A.; Yudina, A. V.; Klyueva, V. V.; Khaidapova, D. D.; Rogov, V. V.

2018-02-01

With the help of computed X-ray microtomography with a resolution of 2.75 μm, changes in the microstructure and pore space of aggregates of 3 mm in diameter from the virgin soddy-podzolic soil (Glossic Retisol (Loamic)) in the air-dry, capillary-moistened, and frozen states after five freeze-thaw cycles were studied in a laboratory experiment. The freezing of the samples was performed at their capillary moistening. It was shown that capillary moistening of initially air-dry samples from the humus (AY), eluvial (EL), and illuvial (BT1) horizons at room temperature resulted in the development of the platy, fine vesicular, and angular blocky microstructure, respectively. The total volume of tomographically visible pores >10 μm increased by 1.3, 2.2, and 3.4 times, respectively. After freeze-thaw cycles, frozen aggregates partly preserved the structural arrangement formed during the capillary moistening. At the same time, in the frozen aggregate from the AY horizon, the total tomographic porosity decreased to the initial level of the air-dry soil. In the frozen aggregate from the EL horizon, large vesicular pores were formed, owing to which the total pore volume retained its increased values. The resistance of aggregate shape to the action of freeze-thaw cycles differed. The aggregate from the EL horizon completely lost its original configuration by the end of the experiment. The aggregate from the AY horizon displayed definite features of sagging after five freeze-thaw cycles, whereas the aggregate from the BT1 horizon preserved its original configuration.

Evaluation of Three Field-Based Methods for Quantifying Soil Carbon

PubMed Central

Izaurralde, Roberto C.; Rice, Charles W.; Wielopolski, Lucian; Ebinger, Michael H.; Reeves, James B.; Thomson, Allison M.; Francis, Barry; Mitra, Sudeep; Rappaport, Aaron G.; Etchevers, Jorge D.; Sayre, Kenneth D.; Govaerts, Bram; McCarty, Gregory W.

2013-01-01

Three advanced technologies to measure soil carbon (C) density (g C m−2) are deployed in the field and the results compared against those obtained by the dry combustion (DC) method. The advanced methods are: a) Laser Induced Breakdown Spectroscopy (LIBS), b) Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS), and c) Inelastic Neutron Scattering (INS). The measurements and soil samples were acquired at Beltsville, MD, USA and at Centro International para el Mejoramiento del Maíz y el Trigo (CIMMYT) at El Batán, Mexico. At Beltsville, soil samples were extracted at three depth intervals (0–5, 5–15, and 15–30 cm) and processed for analysis in the field with the LIBS and DRIFTS instruments. The INS instrument determined soil C density to a depth of 30 cm via scanning and stationary measurements. Subsequently, soil core samples were analyzed in the laboratory for soil bulk density (kg m−3), C concentration (g kg−1) by DC, and results reported as soil C density (kg m−2). Results from each technique were derived independently and contributed to a blind test against results from the reference (DC) method. A similar procedure was employed at CIMMYT in Mexico employing but only with the LIBS and DRIFTS instruments. Following conversion to common units, we found that the LIBS, DRIFTS, and INS results can be compared directly with those obtained by the DC method. The first two methods and the standard DC require soil sampling and need soil bulk density information to convert soil C concentrations to soil C densities while the INS method does not require soil sampling. We conclude that, in comparison with the DC method, the three instruments (a) showed acceptable performances although further work is needed to improve calibration techniques and (b) demonstrated their portability and their capacity to perform under field conditions. PMID:23383225

Convergence of microbial assimilations of soil carbon, nitrogen, phosphorus, and sulfur in terrestrial ecosystems

DOE PAGES

Xu, Xiaofeng; Hui, Dafeng; King, Anthony Wayne; ...

2015-11-27

How soil microbes assimilate carbon-C, nitrogen-N, phosphorus-P, and sulfur-S is fundamental for understanding nutrient cycling in terrestrial ecosystems. We compiled a global database of C, N, P, and S concentrations in soils and microbes and developed relationships between them by using a power function model. The C:N:P:S was estimated to be 287:17:1:0.8 for soils, and 42:6:1:0.4 for microbes. We found a convergence of the relationships between elements in soils and in soil microbial biomass across C, N, P, and S. The element concentrations in soil microbial biomass follow a homeostatic regulation curve with soil element concentrations across C, N, Pmore » and S, implying a unifying mechanism of microbial assimilating soil elements. This correlation explains the well-constrained C:N:P:S stoichiometry with a slightly larger variation in soils than in microbial biomass. Meanwhile, it is estimated that the minimum requirements of soil elements for soil microbes are 0.8 mmol C Kg –1 dry soil, 0.1 mmol N Kg –1 dry soil, 0.1 mmol P Kg –1 dry soil, and 0.1 mmol S Kg –1 dry soil, respectively. Lastly, these findings provide a mathematical explanation of element imbalance in soils and soil microbial biomass, and offer insights for incorporating microbial contribution to nutrient cycling into Earth system models.« less

The effect of sampling scheme in the survey of atmospheric deposition of heavy metals in Albania by using moss biomonitoring.

PubMed

Qarri, Flora; Lazo, Pranvera; Bekteshi, Lirim; Stafilov, Trajce; Frontasyeva, Marina; Harmens, Harry

2015-02-01

The atmospheric deposition of heavy metals in Albania was investigated by using a carpet-forming moss species (Hypnum cupressiforme) as bioindicator. Sampling was done in the dry seasons of autumn 2010 and summer 2011. Two different sampling schemes are discussed in this paper: a random sampling scheme with 62 sampling sites distributed over the whole territory of Albania and systematic sampling scheme with 44 sampling sites distributed over the same territory. Unwashed, dried samples were totally digested by using microwave digestion, and the concentrations of metal elements were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and AAS (Cd and As). Twelve elements, such as conservative and trace elements (Al and Fe and As, Cd, Cr, Cu, Ni, Mn, Pb, V, Zn, and Li), were measured in moss samples. Li as typical lithogenic element is also included. The results reflect local emission points. The median concentrations and statistical parameters of elements were discussed by comparing two sampling schemes. The results of both sampling schemes are compared with the results of other European countries. Different levels of the contamination valuated by the respective contamination factor (CF) of each element are obtained for both sampling schemes, while the local emitters identified like iron-chromium metallurgy and cement industry, oil refinery, mining industry, and transport have been the same for both sampling schemes. In addition, the natural sources, from the accumulation of these metals in mosses caused by metal-enriched soil, associated with wind blowing soils were pointed as another possibility of local emitting factors.

Stochastic soil water balance under seasonal climates

PubMed Central

Feng, Xue; Porporato, Amilcare; Rodriguez-Iturbe, Ignacio

2015-01-01

The analysis of soil water partitioning in seasonally dry climates necessarily requires careful consideration of the periodic climatic forcing at the intra-annual timescale in addition to daily scale variabilities. Here, we introduce three new extensions to a stochastic soil moisture model which yields seasonal evolution of soil moisture and relevant hydrological fluxes. These approximations allow seasonal climatic forcings (e.g. rainfall and potential evapotranspiration) to be fully resolved, extending the analysis of soil water partitioning to account explicitly for the seasonal amplitude and the phase difference between the climatic forcings. The results provide accurate descriptions of probabilistic soil moisture dynamics under seasonal climates without requiring extensive numerical simulations. We also find that the transfer of soil moisture between the wet to the dry season is responsible for hysteresis in the hydrological response, showing asymmetrical trajectories in the mean soil moisture and in the transient Budyko's curves during the ‘dry-down‘ versus the ‘rewetting‘ phases of the year. Furthermore, in some dry climates where rainfall and potential evapotranspiration are in-phase, annual evapotranspiration can be shown to increase because of inter-seasonal soil moisture transfer, highlighting the importance of soil water storage in the seasonal context. PMID:25663808

Relationship between Heavy Metal Concentrations in Soils and Grasses of Roadside Farmland in Nepal

PubMed Central

Yan, Xuedong; Zhang, Fan; Zeng, Chen; Zhang, Man; Devkota, Lochan Prasad; Yao, Tandong

2012-01-01

Transportation activities can contribute to accumulation of heavy metals in roadside soil and grass, which could potentially compromise public health and the environment if the roadways cross farmland areas. Particularly, heavy metals may enter the food chain as a result of their uptake by roadside edible grasses. This research was conducted to investigate heavy metal (Cu, Zn, Cd, and Pb) concentrations in roadside farmland soils and corresponding grasses around Kathmandu, Nepal. Four factors were considered for the experimental design, including sample type, sampling location, roadside distance, and tree protection. A total of 60 grass samples and 60 topsoil samples were collected under dry weather conditions. The Multivariate Analysis of Variance (MANOVA) results indicate that the concentrations of Cu, Zn, and Pb in the soil samples are significantly higher than those in the grass samples; the concentrations of Cu and Pb in the suburban roadside farmland are higher than those in the rural mountainous roadside farmland; and the concentrations of Cu and Zn at the sampling locations with roadside trees are significantly lower than those without tree protection. The analysis of transfer factor, which is calculated as the ratio of heavy-metal concentrations in grass to those in the corresponding soil, indicates that the uptake capabilities of heavy metals from soil to grass is in the order of Zn > Cu > Pb. Additionally, it is found that as the soils’ heavy-metal concentrations increase, the capability of heavy-metal transfer to the grass decreases, and this relationship can be characterized by an exponential regression model. PMID:23202679

Changing Summer Precipitation Pattern Alters Microbial Community Response to Fall Wet-up in a Mediterranean Soil

NASA Astrophysics Data System (ADS)

Barnard, R. L.; Osborne, C. A.; Firestone, M. K.

2014-12-01

The large soil CO2 efflux associated with rewetting dry soils after the dry summer period significantly contributes to the annual carbon budget of Mediterranean grasslands. Rapid reactivation of soil heterotrophic activity and a pulse of available carbon are both required to fuel the CO2 pulse. Better understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting future changes in carbon cycling. Here, we investigated the effects of a controlled rewetting event on the soil CO2 efflux pulse and on the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores previously subjected to three different precipitation patterns over four months (full summer dry season, extended wet season, and absent dry season). Phylogenetic marker genes for bacteria (16S) and fungi (28S) were sequenced before and after rewetting, and the abundance of these genes and transcripts was measured. Even after having experienced markedly different antecedent water conditions, the potentially active bacterial communities showed a consistent wet-up response. Moreover, we found a significant positive relation between the extent of change in the structure of the potentially active bacterial community and the magnitude of the CO2 pulse upon rewetting dry soils. We suggest that the duration of severe dry conditions (predicted to change under future climate) is important in conditioning the response potential of the soil bacterial community to wet-up as well as in framing the magnitude of the associated CO2 pulse.

Changing precipitation pattern alters soil microbial community response to wet-up under a Mediterranean-type climate.

PubMed

Barnard, Romain L; Osborne, Catherine A; Firestone, Mary K

2015-03-17

A large soil CO2 pulse is associated with rewetting soils after the dry summer period under a Mediterranean-type climate, significantly contributing to grasslands' annual carbon budget. Rapid reactivation of soil heterotrophs and a pulse of available carbon are both required to fuel the CO2 pulse. Understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting changes in carbon cycling. Here, we investigated the effects of extending winter rainfall into the normally dry summer period on soil microbial response to a controlled rewetting event, by following the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores (from a California annual grassland) previously subjected to three different precipitation patterns over 4 months (full summer dry season, extended wet season and absent dry season). Phylogenetic marker genes for bacteria and fungi were sequenced before and after rewetting, and the abundance of these genes and transcripts was measured. After having experienced markedly different antecedent water conditions, the potentially active bacterial communities showed a consistent wet-up response. We found a significant positive relation between the extent of change in the structure of the potentially active bacterial community and the magnitude of the CO2 pulse upon rewetting dry soils. We suggest that the duration of severe dry summer conditions characteristic of the Mediterranean climate is important in conditioning the response potential of the soil microbial community to wet-up as well as in framing the magnitude of the associated CO2 pulse.

Critical Evaluation of Soil Pore Water Extraction Methods on a Natural Soil

NASA Astrophysics Data System (ADS)

Orlowski, Natalie; Pratt, Dyan; Breuer, Lutz; McDonnell, Jeffrey

2017-04-01

Soil pore water extraction is an important component in ecohydrological studies for the measurement of δ2H and δ18O. The effect of pore water extraction technique on resultant isotopic signature is poorly understood. Here we present results of an intercomparison of commonly applied lab-based soil water extraction techniques on a natural soil: high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and two types of cryogenic extraction systems. We applied these extraction methods to a natural summer-dry (gravimetric water contents ranging from 8% to 15%) glacio-lacustrine, moderately fine textured clayey soil; excavated in 10 cm sampling increments to a depth of 1 meter. Isotope results were analyzed via OA-ICOS and compared for each extraction technique that produced liquid water. From our previous intercomparison study among the same extraction techniques but with standard soils, we discovered that extraction methods are not comparable. We therefore tested the null hypothesis that all extraction techniques would be able to replicate the natural evaporation front in a comparable manner occurring in a summer-dry soil. Our results showed that the extraction technique utilized had a significant effect on the soil water isotopic composition. High pressure mechanical squeezing and vapor equilibration techniques produced similar results with similarly sloped evaporation lines. Due to the nature of soil properties and dryness, centrifugation was unsuccessful in obtaining pore water for isotopic analysis. Cryogenic extraction on both tested techniques produced similar results to each other on a similar sloping evaporation line, but dissimilar with depth.

Impact of monovalent cations on soil structure. Part II. Results of two Swiss soils

NASA Astrophysics Data System (ADS)

Farahani, Elham; Emami, Hojat; Keller, Thomas

2018-01-01

In this study, we investigated the impact of adding solutions with different potassium and sodium concentrations on dispersible clay, water retention characteristics, air permeability, and soil shrinkage behaviour using two agricultural soils from Switzerland with different clay content but similar organic carbon to clay ratio. Three different solutions (including only Na, only K, and the combination of both) were added to soil samples at three different cation ratio of soil structural stability levels, and the soil samples were incubated for one month. Our findings showed that the amount of readily dispersible clay increased with increasing Na concentrations and with increasing cation ratio of soil structural stability. The treatment with the maximum Na concentration resulted in the highest water retention and in the lowest shrinkage capacity. This was was associated with high amounts of readily dispersible clay. Air permeability generally increased during incubation due to moderate wetting and drying cycles, but the increase was negatively correlated with readily dispersible clay. Readily dispersible clay decreased with increasing K, while readily dispersible clay increased with increasing K in Iranian soil (Part I of our study). This can be attributed to the different clay mineralogy of the studied soils (muscovite in Part I and illite in Part II).

Plant Water Uptake in Drying Soils1

PubMed Central

Lobet, Guillaume; Couvreur, Valentin; Meunier, Félicien; Javaux, Mathieu; Draye, Xavier

2014-01-01

Over the last decade, investigations on root water uptake have evolved toward a deeper integration of the soil and roots compartment properties, with the goal of improving our understanding of water acquisition from drying soils. This evolution parallels the increasing attention of agronomists to suboptimal crop production environments. Recent results have led to the description of root system architectures that might contribute to deep-water extraction or to water-saving strategies. In addition, the manipulation of root hydraulic properties would provide further opportunities to improve water uptake. However, modeling studies highlight the role of soil hydraulics in the control of water uptake in drying soil and call for integrative soil-plant system approaches. PMID:24515834

Effect of dry spells and soil cracking on runoff generation in a semiarid micro watershed under land use change

NASA Astrophysics Data System (ADS)

dos Santos, Julio Cesar Neves; de Andrade, Eunice Maia; Guerreiro, Maria João Simas; Medeiros, Pedro Henrique Augusto; de Queiroz Palácio, Helba Araújo; de Araújo Neto, José Ribeiro

2016-10-01

Soil and water resources effective management and planning in a river basin rely on understanding of runoff generation processes, yield, and their relations to rainfall. This study analyzes the effects of antecedent soil moisture in an expansive soil and the influence of dry spells on soil cracking, runoff generation and yield in a semiarid tropical region in Brazil subject to land use change. Data were collected from 2009 to 2013 in a 2.8 ha watershed, totaling 179 natural rainfall events. In the first year of study (2009), the watershed maintained a typical dry tropical forest cover (arboreal-shrub Caatinga cover). Before the beginning of the second year of study, gamba grass (Andropogon gayanus Kunth) was cultivated after slash and burn of native vegetation. Gamba grass land use was maintained for the rest of the monitoring period. The occurrence of dry spells and the formation of cracks in the Vertisol soil were the most important factors controlling flow generation. Dry spells promoted crack formation in the expansive soil, which acted as preferential flow paths leading to high initial abstractions: average conditions for runoff to be generated included soil moisture content above 20%, rainfall above 70 mm, I30max above 60 mm h-1 and five continuous dry days at the most. The change of vegetation cover in the second year of study did not alter significantly the overall conditions for runoff initiation, showing similar cumulative flow vs. rainfall response, implying that soil conditions, such as humidity and cracks, best explain the flow generation process on the semiarid micro-scale watershed with Vertisol soil.

Drying shrinkage problems in high PI subgrade soils.

DOT National Transportation Integrated Search

2014-01-01

The main objective of this study was to investigate the longitudinal cracking in pavements due to drying : shrinkage of high PI subgrade soils. The study involved laboartory soil testing and modeling. The : shrinkage cracks usually occur within the v...

Effects of the Application of Digestates from Wet and Dry Anaerobic Fermentation to Japanese Paddy and Upland Soils on Short-Term Nitrification

PubMed Central

Sawada, Kozue; Toyota, Koki

2015-01-01

Wet and dry anaerobic fermentation processes are operated for biogas production from organic matter, resulting in wet and dry digestates as by-products, respectively. The application of these digestates to soil as fertilizer has increased in recent years. Therefore, we herein compared the effects of applying wet digestates (pH 8.2, C/N ratio 4.5), dry digestates (pH 8.8, C/N ratio 23.4), and a chemical fertilizer to Japanese paddy and upland soils on short-term nitrification under laboratory aerobic conditions. Chloroform-labile C, an indicator of microbial biomass, was only minimally affected by these applications, indicating that a small amount of labile N was immobilized by microbes. All applications led to rapid increases in NO3 -N contents in both soils, and ammonia-oxidizing bacteria, but not archaea may play a critical role in net nitrification in the amended soils. The net nitrification rates for both soils were the highest after the application of dry digestates, followed by wet digestates and then the chemical fertilizer in order of decreasing soil pH. These results suggest that the immediate effects of applying digestates, especially dry digestates with the highest pH, on nitrate leaching need to be considered when digestates are used as alternative fertilizers. PMID:25740173

Effects of the application of digestates from wet and dry anaerobic fermentation to Japanese paddy and upland soils on short-term nitrification.

PubMed

Sawada, Kozue; Toyota, Koki

2015-01-01

Wet and dry anaerobic fermentation processes are operated for biogas production from organic matter, resulting in wet and dry digestates as by-products, respectively. The application of these digestates to soil as fertilizer has increased in recent years. Therefore, we herein compared the effects of applying wet digestates (pH 8.2, C/N ratio 4.5), dry digestates (pH 8.8, C/N ratio 23.4), and a chemical fertilizer to Japanese paddy and upland soils on short-term nitrification under laboratory aerobic conditions. Chloroform-labile C, an indicator of microbial biomass, was only minimally affected by these applications, indicating that a small amount of labile N was immobilized by microbes. All applications led to rapid increases in NO3 -N contents in both soils, and ammonia-oxidizing bacteria, but not archaea may play a critical role in net nitrification in the amended soils. The net nitrification rates for both soils were the highest after the application of dry digestates, followed by wet digestates and then the chemical fertilizer in order of decreasing soil pH. These results suggest that the immediate effects of applying digestates, especially dry digestates with the highest pH, on nitrate leaching need to be considered when digestates are used as alternative fertilizers.

Do drying and rewetting cycles modulate effects of sulfadiazine spiked manure in soil?

PubMed

Jechalke, Sven; Radl, Viviane; Schloter, Michael; Heuer, Holger; Smalla, Kornelia

2016-05-01

Naturally occurring drying-rewetting events in soil have been shown to affect the dissipation of veterinary antibiotics entering soil by manure fertilization. However, knowledge of effects on the soil microbial community structure and resistome is scarce. Here, consequences of drying-rewetting cycles on effects of sulfadiazine (SDZ) in soil planted with Dactylis glomerata L. were investigated in microcosms. Manure containing SDZ or not was applied to the pregrown grass and incubated for 56 days in a climate chamber. Water was either added daily or reduced during two drying events of 7 days, each followed by a recovery phase. Total community DNA was analyzed to reveal the effects on the bacterial community structure and on the abundance of sul1, sul2, intI1 ,intI2, qacE+qacEΔ1, traN and korB genes relative to 16S rRNA genes. 16S rRNA gene-based DGGE fingerprints indicated that drying-rewetting cycles modulated the effects of SDZ on the bacterial community structure in the soil. Furthermore, the SDZ treatment increased the relative abundance of sulfonamide resistance and integrase genes compared to the control. However, this increase was not different between moisture regimes, indicating that drying-rewetting had only a negligible effect on the selection of the resistome by SDZ in the manured soil. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mineralogy of Antarctica Dry Valley Soils: Implications for Pedogenic Processes on Mars

NASA Technical Reports Server (NTRS)

Quinn, J. E.; Ming, D. W.; Morris, R. V.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Tamppari, L, K.; Smith, P. H.; Zent, A. P.; Archer, P. D., Jr.

2010-01-01

The Antarctic Dry Valleys (ADVs) located in the Transantarctic Mountains are the coldest and driest locations on Earth. The mean annual air temperature is -20 C or less and the ADVs receive 100mm or less of precipitation annually in the form of snow. The cold and dry climate in the ADVs is one of the best terrestrial analogs for the climatic conditions on Mars [2]. The soils in the ADVs have been categorized into three soil moisture zones: subxerous, xerous and ultraxerous. The subxerous zone is a coastal region in which soils have ice-cemented permafrost relatively close to the surface. Moisture is available in relatively large amounts and soil temperatures are above freezing throughout the soil profile (above ice permafrost) in summer months. The xerous zone, the most widespread of the three zones, is an inland region with a climate midway between the subxerous and ultraxerous. The soils from this zone have dry permafrost at moderate depths (30-75cm) but have sufficient water in the upper soil horizons to allow leaching of soluble materials. The ultraxerous zone is a high elevation zone, where both temperature and precipitation amounts are very low resulting in dry permafrost throughout the soil profile. The three moisture regime regions are similar to the three microclimatic zones (coastal thaw, inland mixed, stable upland) defined by Marchant and Head.

Thermal Desorption Analysis of Effective Specific Soil Surface Area

NASA Astrophysics Data System (ADS)

Smagin, A. V.; Bashina, A. S.; Klyueva, V. V.; Kubareva, A. V.

2017-12-01

A new method of assessing the effective specific surface area based on the successive thermal desorption of water vapor at different temperature stages of sample drying is analyzed in comparison with the conventional static adsorption method using a representative set of soil samples of different genesis and degree of dispersion. The theory of the method uses the fundamental relationship between the thermodynamic water potential (Ψ) and the absolute temperature of drying ( T): Ψ = Q - aT, where Q is the specific heat of vaporization, and a is the physically based parameter related to the initial temperature and relative humidity of the air in the external thermodynamic reservoir (laboratory). From gravimetric data on the mass fraction of water ( W) and the Ψ value, Polyanyi potential curves ( W(Ψ)) for the studied samples are plotted. Water sorption isotherms are then calculated, from which the capacity of monolayer and the target effective specific surface area are determined using the BET theory. Comparative analysis shows that the new method well agrees with the conventional estimation of the degree of dispersion by the BET and Kutilek methods in a wide range of specific surface area values between 10 and 250 m2/g.

Hydrologic regime controls soil phosphorus fluxes in restoration and undisturbed wetlands

USGS Publications Warehouse

Aldous, A.; McCormick, P.; Ferguson, C.; Graham, S.; Craft, C.

2005-01-01

Many wetland restoration projects occur on former agricultural soils that have a history of disturbance and fertilization, making them prone to phosphorus (P) release upon flooding. To study the relationship between P release and hydrologic regime, we collected soil cores from three restoration wetlands and three undisturbed wetlands around Upper Klamath Lake in southern Oregon, U.S.A. Soil cores were subjected to one of three hydrologic regimes - flooded, moist, and dry - for 7.5 weeks, and P fluxes were measured upon reflooding. Soils from restoration wetlands released P upon reflooding regardless of the hydrologic regime, with the greatest releases coming from soils that had been flooded or dried. Undisturbed wetland soils released P only after drying. Patterns in P release can be explained by a combination of physical and biological processes, including the release of iron-bound P due to anoxia in the flooded treatment and the mineralization of organic P under aerobic conditions in the dry treatment. Higher rates of soil P release from restoration wetland soils, particularly under flooded conditions, were associated with higher total P concentrations compared with undisturbed wetland soils. We conclude that maintaining moist soil is the means to minimize P release from recently flooded wetland soils. Alternatively, prolonged flooding provides a means of liberating excess labile P from former agricultural soils while minimizing continued organic P mineralization and soil subsidence. ?? 2005 Society for Ecological Restoration International.

The Effect of a Planetary Surface Penetrator on the Soil Column Surrounding the Impacting Body

NASA Technical Reports Server (NTRS)

Blanchard, Maxwell B.; Shade, Harry D.

1975-01-01

A prototype penetrator instrument was impacted into a dry lake bed. Laboratory studies of the soil surrounding the penetrator revealed that the soil was contaminated by paint and metal from the penetrator's casing. Paint pigment rich in titanium and sulfur was found in the adjacent soil. The highly mobile paint pigment migrated onto viewing ports in the penetrator's exterior. Bulk analysis of the soil adjacent to the impactor showed a significant increase in both elements, as well as the presence of metal chips from the casing and nose cone. It is recommended that great care be taken in the use of coating materials and the metal alloys selected for the penetrator's exterior, or the accuracy of any experiment requiring an uncontaminated in situ sample may be adversely affected.

Completing below-ground carbon budgets for pastures, recovering forests, and mature forests of Amazonia

NASA Technical Reports Server (NTRS)

Davidson, Eric A.; Nepstad, Daniel C.; Trumbore, Susan E.

1994-01-01

The objective of this grant was to complete below-ground carbon budgets for pastures and forest soils in the Amazon. Profiles of radon and carbon dioxide were used to estimate depth distribution of CO2 production in soil. This information is necessary for determining the importance of deep roots as sources of carbon inputs. Samples were collected for measuring root biomass from new research sites at Santana de Araguaia and Trombetas. Soil gases will be analyzed for CO2 and (14)CO2, and soil organic matter will be analyzed for C-14. Estimates of soil texture from the RADAMBRASIL database were merged with climate data to calculate soil water extraction by forest canopies during the dry season. In addition, a preliminary map of areas where deep roots are needed for deep soil water was produced. A list of manuscripts and papers prepared during the reporting periods is given.

Wet and Dry Atmospheric Mercury Deposition Accumulates in Watersheds of the Northeastern United States

NASA Astrophysics Data System (ADS)

Boyer, E. W.; Grant, C.; Grimm, J.; Drohan, P. J.; Bennett, J.; Lawler, D.

2013-12-01

Mercury emissions to the atmosphere from coal-fired power plants and other sources such as waste incineration can be deposited to landscapes in precipitation and in dry fallout. Some mercury reaches watersheds and streams, where it can accumulate in sediments and biota. Human exposure to mercury occurs primarily through fish consumption, and currently mercury fish eating advisories are in place for many of the streams and lakes in the state. Here, we explored mercury in air, soils, water, and biota. To quantify atmospheric mercury deposition, we measured both wet and dry mercury deposition at over 10 locations in Pennsylvania, from which we present variation in mercury deposition and initial assessments of factors affecting the patterns. Further, we simulated mercury deposition at unmonitored locations in Pennsylvania and the northeastern United States over space and time with a high-resolution modeling technique that reflects storm tracks and air flow patterns. To consider mercury accumulation in watersheds, we collected data on soil mercury concentrations in a set of soil samples, and collected baseline data on mercury in streams draining 35 forested watersheds across Pennsylvania, spanning gradients of atmospheric deposition, climate and geology. Mercury concentrations were measured in stream water under base-flow conditions, in streambed sediments, aquatic mosses, and in fish tissues from brook trout. Results indicate that wet and dry atmospheric deposition is a primary source of mercury that is accumulating in watersheds of Pennsylvania and the northeastern United States.

Plutonium isotopes in the Hungarian environment.

PubMed

Varga, Beata; Tarján, Sandor; Vajda, Nora

2008-04-01

More than 50 soil samples were analysed from different parts of the country, the activity concentration of 239+240Pu was in the range of 0.01-0.84 Bq/kg dry soil with the average of 0.10 Bq/kg. 238Pu could be detected only in few moss samples and 238Pu/239+240Pu ratio determines the origin of plutonium. 241Pu was determined by liquid scintillation spectrometry. The activity concentration of this isotope in the soil is between 0.04 and 3.74 Bq/kg with the average of 0.82 Bq/kg, while in the moss is also similar 0.01-2.07 Bq/kg fresh mass with the average of 0.43 Bq/kg. Significant difference could not be observed between the different types of soils occurring in the country, but the results could be sorted according to the sampling carried out on undisturbed or cultivated area. The isotope ratios 241Pu/239+240Pu prove that the origin of the plutonium in Hungary is the global fallout determined by the atmospheric nuclear weapon tests.

Factors influencing the contents of metals and as in soils around the watershed of Guanting Reservoir, China.

PubMed

Xu, Li; Wang, Tieyu; Luo, Wei; Ni, Kun; Liu, Shijie; Wang, Lin; Li, Qiushuang; Lu, Yonglong

2013-03-01

Topsoil samples from 61 sites around the Guanting Reservoir, China, were measured for Cu, Zn, Cr, Ni, Cd, Pb and As concentrations. The mean concentrations of Cu, Zn, Cr, Ni, Cd, Pb and As were 16.8, 59.4, 37.8, 18.3, 0.32, 20.1 and 8.67 mg/kg dry weight, respectively. Factors that influence the dynamics of these metals in soils around the watersheds of Beijing reservoirs were examined. The influence of atmospheric deposition, land use, soil texture, soil type and soil chemical parameters on metal contents in soils was investigated. Atmospheric deposition, land use and soil texture were the important factors affecting heavy metal residues. Soil type and soil chemical parameters were also involved in heavy metal retention in soils. The data provided in this study are considered crucial for reservoir remediation, especially since the Guanting Reservoir will serve as one of the main drinking water sources for Beijing in the foreseeable future.

Peat Soil Stabilization using Lime and Cement

NASA Astrophysics Data System (ADS)

Zambri, Nadhirah Mohd; Ghazaly, Zuhayr Md.

2018-03-01

This paper presents a study of the comparison between two additive Lime and Cement for treating peat soil in term of stabilization. Peat and organic soils are commonly known for their high compressibility, extremely soft, and low strength. The aim of this paper is to determine the drained shear strength of treated peat soil from Perlis for comparison purposes. Direct Shear Box Test was conducted to obtain the shear strength for all the disturbed peat soil samples. The quick lime and cement was mixed with peat soil in proportions of 10% and 20% of the dry weight peat soil. The experiment results showed that the addition of additives had improved the strength characteristics of peat soil by 14% increment in shear strength. In addition, the mixture of lime with peat soil yield higher result in shear strength compared to cement by 14.07% and 13.5% respectively. These findings indicate that the lime and cement is a good stabilizer for peat soil, which often experienced high amount of moisture content.

Arbuscular mycorrhizal fungi and associated microbial communities from dry grassland do not improve plant growth on abandoned field soil.

PubMed

Pánková, Hana; Lepinay, Clémentine; Rydlová, Jana; Voříšková, Alena; Janoušková, Martina; Dostálek, Tomáš; Münzbergová, Zuzana

2018-03-01

After abandonment of agricultural fields, some grassland plant species colonize these sites with a frequency equivalent to dry grasslands (generalists) while others are missing or underrepresented in abandoned fields (specialists). We aimed to understand the inability of specialists to spread on abandoned fields by exploring whether performance of generalists and specialists depended on soil abiotic and/or biotic legacy. We performed a greenhouse experiment with 12 species, six specialists and six generalists. The plants were grown in sterile soil from dry grassland or abandoned field inoculated with microbial communities from one or the other site. Plant growth, abundance of mycorrhizal structures and plant response to inoculation were evaluated. We focused on arbuscular mycorrhizal fungi (AMF), one of the most important parts of soil communities affecting plant performance. The abandoned field soil negatively affected plant growth, but positively affected plant response to inoculation. The AMF community from both sites differed in infectivity and taxa frequencies. The lower AMF taxa frequency in the dry grassland soil suggested a lack of functional complementarity. Despite the fact that dry grassland AMF produced more arbuscules, the dry grassland inoculum did not improve phosphorus nutrition of specialists contrary to the abandoned field inoculum. Inoculum origin did not affect phosphorus nutrition of generalists. The lower effectiveness of the dry grassland microbial community toward plant performance excludes its inoculation in the abandoned field soil as a solution to allow settlement of specialists. Still, the distinct response of specialists and generalists to inoculation suggested that they differ in AMF responsiveness.

Pitfall Traps and Mini-Winkler Extractor as Complementary Methods to Sample Soil Coleoptera.

PubMed

Carneiro, A C; Batistella, D A; Battirola, L D; Marques, M I

2016-02-01

We compared abundance, species richness, and capture efficiency with pitfall traps and mini-Winkler extractors to examine their use as complementary methods for sampling soil Coleoptera during dry (2010) and high water seasons (2011) in three areas, including inundated and non-inundated regions, in the Pantanal of Poconé, Mato Grosso, Brazil. We paired treatments with two 10 × 10 m plots in inundated and non-inundated locations that were repeated three times in each location for a total of 18 plots. In each plot, we used nine pitfall traps and collected 2 m(2) of leaf litter and surface soil samples with mini-Winkler extractors. We collected a total of 4260 adult beetles comprising 36 families, 113 genera, and 505 species. Most were caught in pitfalls (69%) and the remainder in the mini-Winkler extractors (31%). Each method provided distinct information about the beetle community: 252 species were captured only in pitfall traps, 147 using only the mini-Winkler extractors, and these methods shared another 106 species. Pitfall and mini-Winkler contribute in different ways for the sampling of the soil beetle community, and so they should be considered complementary for a more thorough assessment of community diversity.

Development of a robust chromatographic method for the detection of chlorophenols in cork oak forest soils.

PubMed

McLellan, Iain; Hursthouse, Andrew; Morrison, Calum; Varela, Adélia; Pereira, Cristina Silva

2014-02-01

A major concern for the cork and wine industry is 'cork taint' which is associated with chloroanisoles, the microbial degradation metabolites of chlorophenols. The use of chlorophenolic compounds as pesticides within cork forests was prohibited in 1993 in the European Union (EU) following the introduction of industry guidance. However, cork produced outside the EU is still thought to be affected and simple, robust methods for chlorophenol analysis are required for wider environmental assessment by industry and local environmental regulators. Soil samples were collected from three common-use forests in Tunisia and from one privately owned forest in Sardinia, providing examples of varied management practice and degree of human intervention. These provided challenge samples for the optimisation of a HPLC-UV detection method. It produced recoveries consistently >75% against a soil CRM (ERM-CC008) for pentachlorophenol. The optimised method, with ultraviolet (diode array) detection is able to separate and quantify 16 different chlorophenols at field concentrations greater than the limits of detection ranging from 6.5 to 191.3 μg/kg (dry weight). Application to a range of field samples demonstrated the absence of widespread contamination in forest soils at sites sampled in Sardinia and Tunisia.

Spatial prediction of near surface soil water retention functions using hydrogeophysics and empirical orthogonal functions

NASA Astrophysics Data System (ADS)

Gibson, Justin; Franz, Trenton E.

2018-06-01

The hydrological community often turns to widely available spatial datasets such as the NRCS Soil Survey Geographic database (SSURGO) to characterize the spatial variability of soil properties. When used to spatially characterize and parameterize watershed models, this has served as a reasonable first approximation when lacking localized or incomplete soil data. Within agriculture, soil data has been left relatively coarse when compared to numerous other data sources measured. This is because localized soil sampling is both expensive and time intense, thus a need exists in better connecting spatial datasets with ground observations. Given that hydrogeophysics is data-dense, rapid, non-invasive, and relatively easy to adopt, it is a promising technique to help dovetail localized soil sampling with spatially exhaustive datasets. In this work, we utilize two common near surface geophysical methods, cosmic-ray neutron probe and electromagnetic induction, to identify temporally stable spatial patterns of measured geophysical properties in three 65 ha agricultural fields in western Nebraska. This is achieved by repeat geophysical observations of the same study area across a range of wet to dry field conditions in order to evaluate with an empirical orthogonal function. Shallow cores were then extracted within each identified zone and water retention functions were generated in the laboratory. Using EOF patterns as a covariate, we quantify the predictive skill of estimating soil hydraulic properties in areas without measurement using a bootstrap validation analysis. Results indicate that sampling locations informed via repeat hydrogeophysical surveys, required only five cores to reduce the cross-validation root mean squared error by an average of 64% as compared to soil parameters predicted by a commonly used benchmark, SSURGO and ROSETTA. The reduction to five strategically located samples within the 65 ha fields reduces sampling efforts by up to ∼90% as compared to the common practice of soil grid sampling every 1 ha.

Changes in Microbial Community Structure and Soil Biological Properties in Mined Dune Areas During Re-vegetation.

PubMed

Escobar, Indra Elena C; Santos, Vilma M; da Silva, Danielle Karla A; Fernandes, Marcelo F; Cavalcante, Uided Maaze T; Maia, Leonor C

2015-06-01

The aim of this study was to describe the impact of re-vegetation on the restoration of microbial community structure and soil microbiological properties in sand dunes that had been affected by mining activity. Soil samples were collected during the dry and rainy seasons from a chronosequence (1, 9, 21 years) of re-vegetated dunes using a single preserved dune as a reference. The composition of the fatty acid methyl esters and soil microbial properties were evaluated. The results showed that the changes in microbial community structure were related to seasonal variations: biomarkers of Gram-positive bacteria were higher than Gram-negative bacteria during the dry season, showing that this group of organisms is more tolerant to these stressful conditions. The microbial community structure in the natural dune was less affected by seasonal variation compared to the re-vegetated areas, whereas the opposite was observed for microbiological properties. Thus, in general, the proportion of saprobic fungi was higher in the natural dune, whereas Gram-negative bacteria were proportionally more common in the younger areas. Although over time the re-vegetation allows the recovery of the microbial community and the soil functions, these communities and functions are different from those found in the undisturbed areas.

Off-Site Radiation Exposure Review Project: Phase 2 soils program

DOE Office of Scientific and Technical Information (OSTI.GOV)

McArthur, R.D.; Miller, F.L. Jr.

1989-12-01

To help estimate population doses of radiation from fallout originating at the Nevada Test Site, soil samples were collected throughout the western United States. Each sample was prepared by drying and ball-milling, then analyzed by gamma-spectrometry to determine the amount of {sup 137}Cs it contained. Most samples were also analyzed by chemical separation and alpha-spectrometry to determine {sup 239 + 240}Pu and by isotope mass spectroscopy to determine the ratios of {sup 240}Pu to {sup 239}Pu and {sup 241}Pu to {sup 239}Pu. The total inventories of cesium and plutonium at 171 sites were computed from the results. This report describesmore » the sample collection, processing, and analysis, presents the analytical results, and assesses the quality of the data. 10 refs., 9 figs., 12 tabs.« less

Erodibility of waste (Loess) soils from construction sites under water and wind erosional forces.

PubMed

Tanner, Smadar; Katra, Itzhak; Argaman, Eli; Ben-Hur, Meni

2018-03-01

Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0-0.3m) and subsoil layers (0.3-0.9 and >1m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility (K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. Copyright © 2017 Elsevier B.V. All rights reserved.

Spatial prediction of near surface soil water retention functions using hydrogeophysics

NASA Astrophysics Data System (ADS)

Gibson, J. P.; Franz, T. E.

2017-12-01

The hydrological community often turns to widely available spatial datasets such as SSURGO to characterize the spatial variability of soil across a landscape of interest. This has served as a reasonable first approximation when lacking localized soil data. However, previous work has shown that information loss within land surface models primarily stems from parameterization. Localized soil sampling is both expensive and time intense, and thus a need exists in connecting spatial datasets with ground observations. Given that hydrogeophysics is data-dense, rapid, and relatively easy to adopt, it is a promising technique to help dovetail localized soil sampling with larger spatial datasets. In this work, we utilize 2 geophysical techniques; cosmic ray neutron probe and electromagnetic induction, to identify temporally stable soil moisture patterns. This is achieved by measuring numerous times over a range of wet to dry field conditions in order to apply an empirical orthogonal function. We then present measured water retention functions of shallow cores extracted within each temporally stable zone. Lastly, we use soil moisture patterns as a covariate to predict soil hydraulic properties in areas without measurement and validate using a leave-one-out cross validation analysis. Using these approaches to better constrain soil hydraulic property variability, we speculate that further research can better estimate hydrologic fluxes in areas of interest.

Elemental assessment of vegetation via portable X-ray fluorescence (PXRF) spectrometry.

PubMed

McGladdery, Candice; Weindorf, David C; Chakraborty, Somsubhra; Li, Bin; Paulette, Laura; Podar, Dorina; Pearson, Delaina; Kusi, Nana Yaw O; Duda, Bogdan

2018-03-15

Elemental concentrations in vegetation are of critical importance, whether establishing plant essential element concentrations (toxicity vs. deficiency) or investigating deleterious elements (e.g., heavy metals) differentially extracted from the soil by plants. Traditionally, elemental analysis of vegetation has been facilitated by acid digestion followed by quantification via inductively coupled plasma (ICP) or atomic absorption (AA) spectroscopy. Previous studies have utilized portable X-ray fluorescence (PXRF) spectroscopy to quantify elements in soils, but few have evaluated the vegetation. In this study, a PXRF spectrometer was employed to scan 228 organic material samples (thatch, deciduous leaves, grasses, tree bark, and herbaceous plants) from smelter-impacted areas of Romania, as well as National Institute of Standards and Technology (NIST) certified reference materials, to demonstrate the application of PXRF for elemental determination in vegetation. Samples were scanned in three conditions: as received from the field (moist), oven dry (70 °C), and dried and powdered to pass a 2 mm sieve. Performance metrics of PXRF models relative to ICP atomic emission spectroscopy were developed to asses optimal scanning conditions. Thatch and bark samples showed the highest mean PXRF and ICP concentrations (e.g., Zn, Pb, Cd, Fe), with the exceptions of K and Cl. Validation statistics indicate that the stable validation predictive capacity of PXRF increased in the following order: oven dry intact < field moist < oven dried and powdered. Even under field moist conditions, PXRF could reasonably be used for the determination of Zn (coefficient of determination, R 2 val 0.86; residual prediction deviation, RPD 2.72) and Cu (R 2 val 0.77; RPD 2.12), while dried and powdered samples allowed for stable validation prediction of Pb (R 2 val 0.90; RPD 3.29), Fe (R 2 val 0.80; RPD 2.29), Cd (R 2 val 0.75; RPD 2.07) and Cu (R 2 val 0.98; RPD of 8.53). Summarily, PXRF was shown to be a useful approach for quickly assessing the elemental concentration in vegetation. Future PXRF/vegetation research should explore additional elements and investigate its usefulness in evaluating phytoremediation effectiveness. Copyright © 2018 Elsevier Ltd. All rights reserved.

Long-term effects of crude oil contamination and bioremediation in a soil ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, K.; Levetin, E.; Buck, P.

1995-12-31

Analysis of samples taken from three experimental soil lysimeters demonstrate marked effects on the soil chemistry and on bacterial, fungal, nematode, and plant communities three years after the application of crude oil. The lysimeters are located at the Amoco Production Research Environmental Test Facility in Rogers County, OK, and were originally used to evaluate the effectiveness of managed (application of fertilizer and water, one lysimeter) vs. unmanaged bioremediation (one lysimeter) of Michigan Silurian crude oil compared to one uncontaminated control lysimeter. Five, two-foot-long soil cores were extracted from each lysimeter, each divided into three sections, and the like sections mixedmore » together to form composited soil samples. All subsequent chemical and microbiological analyses were performed on these nine composited samples. Substantial variation was found among the lysimeters for certain soil chemical characteristics [% moisture, pH, total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH{sub 4}-N), phosphate phosphorous (PO{sub 4}-P), and sulfate (SO{sub 4}{sup -2})]. The managed lysimeter had 10% the level of total petroleum hydrocarbons (TPH-IR) as did the unmanaged lysimeter. Assessment of the microbial community was performed for heterotropic: bacteria, fungi, and aromatic hydrocarbon-degrading bacteria by dilution onto solid media. Hydrocarbon degrading bacteria were elevated in both oil-contaminated lysimeters. Nematodes were extracted from soil samples, identified to genus, and classified according to their mode of nutrition. All vegetation and roots were removed from each lysimeter after the soil samples were taken, representative plants were pressed for identification, and the dry weight of all plants (total biomass) for each lysimeter was determined. The plant species were predominantly those found in disturbed habitats.« less

Impact of charcoal waste application on the soil organic matter content and composition of an Haplic Cambisol from South Brazil

NASA Astrophysics Data System (ADS)

dos Anjos Leal, Otávio; Pinheiro Dick, Deborah; Cylene Lombardi, Kátia; Gonçalves Maciel, Vanessa

2014-05-01

In some regions in Brazil, charcoal is usually applied to the soil with the purpose to improve its fertility and its organic carbon (SOC) content. In Brazil, the use of charcoal waste from steel industry with agronomic purposes represents also an alternative and sustainable fate for this material. In this context, the objective of this work was to evaluate the impact of Eucalyptus charcoal waste application on the SOC content and on the soil organic matter (SOM) composition. Increasing doses of charcoal (0, 10, 20 and 40 Mg ha-1) were applied to an Haplic Cambisol, in Irati, South-Brazil. Charcoal was initially applied on the soil surface, and then it was incorporated at 10 cm with a harrow. Soil undisturbed and disturbed samples (four replicates) were collected in September 2011 (1 y and 9 months) after charcoal incorporation. Four soil depths were evaluated (0-5, 5-10, 10-20 and 20-30 cm) and each replicate was composed by three subsamples collected within each plot. The soil samples were air dried, passed through a 9.51 mm sieve and thereafter through a 2.00 mm sieve. The SOC content and total N were quantified by dry combustion. The SOM was concentrated with fluoridric acid 10% and then the SOM composition was evaluated by thermogravimetric analysis along the soil profile. The main impact of charcoal application occurred at the 0-5 cm layer of the area treated with the highest dose: SOC content increased in 15.5 g kg-1 in comparison to the soil without charcoal application. The intermediary doses also increased the SOC content, but the differences were not significant. No differences for N content were found in this soil depth. Further results were observed in the 10-20 cm soil depth, where the highest dose increased the SOC content and N content. Furthermore, this treatment increased the recalcitrance of the SOM, mainly at the 0-5 cm and 10-20 cm soil layers. No differences between doses of charcoal application were found in the 20-30 cm soil depth, suggesting that the charcoal has not migrated so deep in soil even after almost two years of its incorporation.

Improved Instrument for Detecting Water and Ice in Soil

NASA Technical Reports Server (NTRS)

Buehler, Martin; Chin, Keith; Keymeulen, Didler; McCann, Timothy; Seshadri, Suesh; Anderson, Robert

2009-01-01

An instrument measures electrical properties of relatively dry soils to determine their liquid water and/or ice contents. Designed as a prototype of instruments for measuring the liquid-water and ice contents of lunar and planetary soils, the apparatus could also be utilized for similar purposes in research and agriculture involving terrestrial desert soils and sands, and perhaps for measuring ice buildup on aircraft surfaces. This instrument is an improved version of the apparatus described in Measuring Low Concentrations of Liquid Water and Ice in Soil (NPO-41822), NASA Tech Briefs, Vol. 33, No. 2 (February 2009), page 22. The designs of both versions are based on the fact that the electrical behavior of a typical soil sample is well approximated by a network of resistors and capacitors in which resistances decrease and capacitances increase (and the magnitude and phase angle of impedance changes accordingly) with increasing water content. The previous version included an impedance spectrometer and a jar into which a sample of soil was placed. Four stainless-steel screws at the bottom of the jar were used as electrodes of a fourpoint impedance probe connected to the spectrometer. The present instrument does not include a sample jar and can be operated without acquiring or handling samples. Its impedance probe consists of a compact assembly of electrodes housed near the tip of a cylinder. The electrodes protrude slightly from the cylinder (see Figure 1). In preparation for measurements, the cylinder is simply pushed into the ground to bring the soil into contact with the electrodes.

Drought Impact on the Soilborne Fungal Pathogen of Tomato: Fusarium Oxysporum f. sp. Lycopersici Race 3

NASA Astrophysics Data System (ADS)

Raju, T.

2016-12-01

This paper reviews the drought impact on fungal pathogen of tomato. It presents the 11 Main Procedures used to conduct the experiments and discusses materials used. The 11 procedures are: Gather All the Soils, Sterilize the Soils Using Auto-Clave, Water Retention Test Using Auto-Clave, Cultivate Pathogen, Grow Tomato Plant, Count Pathogenic Cells, Inoculate the Pathogen, Conduct Root Dip, Grow Positive and Negative Samples, Test for Fusarium, and the Soil Separation Experiment with Pathogenic Soil. Experiments conducted on 6 Main Soils used in farming throughout California. The Yolo Series, Whiterock Series, Euic Soil, Potting Soil, Blacklock Series, and Henneke Series. The 6 Soils include amounts of clay, silt, sand, loam, and humus. It was crucial that these soils include these properties because deriving from last year's research I found that these particles in the soil has a role in the growth of the plant. Next, I tested the dry/wet weight of the soils, as this gave me a good estimate of how much water the soils can retain. This is very important because I found a direct correlation between the soil that retained the most amount of water and the soil that had the least harms done. Next, the other labs were completed to cultivate, inoculate, and test the pathogens in the soil, now these steps must be carried out with accuracy and precision because pathogens are a biological agent that causes disease or illness to its host, and if even 0.100 mL is changed in the pathogenic level it can make a large difference. Later, after I finished conducting the root dip, and raising the tomato plants. I counted the Fusarium count in the soil and plated the samples, where I was able to find the results on how much harm the pathogen had on the plant. In each of the 90 reps. the Fusarium (soilborne pathogen) decreased a little, which factors in the transfer from Potato Dextrose Agar Petri Dish to the Soils. After, this transfer the pathogen decreased and never increased, but from my Pathogen Severity Experiment, the harms done to the Early Pak 7 Tomato Plants were much greater, in soils with lower amounts of pathogen. This is because the pathogen was dying in soils with low water content, and dry material. Since, the soil was poor the plant's vascular system was weak, thus it was easier for a small Colony Forming Unit to weaken the plant and eventually kill it.

A toxicity test in artificial soil based on the life-history strategy of the nematode Plectus acuminatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kammenga, J.E.; Van Koert, P.H.G.; Riksen, J.A.G.

1996-05-01

The ecological risk assessment of toxicants in soil requires reproducible and relevant test systems using a wide range of species. To supplement present test methods from the Organisation of Economic Cooperation and Development (OECD) in artificial soil with earthworms and springtails, a toxicity test in OECD artificial soil has been developed using the bacterivorous nematode Plectus acuminatus (Bastian, 1865) (Nematoda; Plectidae). The juvenile to adult ratio was used as a test parameter since previous life-cycle studies pointed out that fitness of P. acuminatus was strongly determined by changes in both reproduction and juvenile survival. Optimal conditions for the performance ofmore » nematodes in OECD artificial soil were determined (pH{sub KCl} = 5.5, temperature = 20C, and a moisture content of 70% dry wt. artificial soil), and tests were conducted with cadmium, copper, and pentachlorophenol. After an exposure period of 3 weeks the EC50 for cadmium was 321.0 {+-} 1.7 mg/kg dry wt., and the no-observed-effect concentration (NOEC) was 32 mg/kg dry wt. The EC50 for pentachlorophenol was 47.9 {+-} 1.2 mg/kg dry wt., and the NOEC was <10 mg/kg dry wt. For copper the EC50 was 162 {+-} 0.2 mg/kg dry wt., and the NOEC was 32 mg/kg dry wt. It is concluded that the nematode test may well supplement current coil test systems using earthworms and springtails.« less

Soil water storage, rainfall and runoff relationships in a tropical dry forest catchment

NASA Astrophysics Data System (ADS)

Farrick, Kegan K.; Branfireun, Brian A.

2014-12-01

In forested catchments, the exceedance of rainfall and antecedent water storage thresholds is often required for runoff generation, yet to our knowledge these threshold relationships remain undescribed in tropical dry forest catchments. We, therefore, identified the controls of streamflow activation and the timing and magnitude of runoff in a tropical dry forest catchment near the Pacific coast of central Mexico. During a 52 day transition phase from the dry to wet season, soil water movement was dominated by vertical flow which continued until a threshold soil moisture content of 26% was reached at 100 cm below the surface. This satisfied a 162 mm storage deficit and activated streamflow, likely through lateral subsurface flow pathways. High antecedent soil water conditions were maintained during the wet phase but had a weak influence on stormflow. We identified a threshold value of 289 mm of summed rainfall and antecedent soil water needed to generate >4 mm of stormflow per event. Above this threshold, stormflow response and magnitude was almost entirely governed by rainfall event characteristics and not antecedent soil moisture conditions. Our results show that over the course of the wet season in tropical dry forests the dominant controls on runoff generation changed from antecedent soil water and storage to the depth of rainfall.

Intestinal parasites in children and soil from Turbaco, Colombia and associated risk factors.

PubMed

Villafañe-Ferrer, Lucy M; Pinilla-Pérez, Mavianis

2016-02-01

Objective To determine the frequency of intestinal parasites in children and soil from Turbaco- Colombia and associated risks factors. Methods Analytical study in which 390 children between 2 and 12 years old from 10 neighborhoods of Turbaco were included, whose legal representatives gave informed consent. Three serial samples of feces and 10 soil samples were processed. Risk factors were determined through an interview. Physicochemical and structural characteristics of soils were also evaluated. Results Parasites were found in 30.5 % of children. 162 parasites were observed; the most frequent protozoan was Endolimax nana (30.3 %) and in terms of helminthes, the most frequent was Ascaris lumbricoides (4.9 %). No statistical association between age or sex and intestinal parasites (p>0.05) or between risk factors and intestinal parasites (p>0.05) was found. Low frequencies of intestinal parasites were encountered in soil samples, being more common Entamoeba spp., Giardia spp., and Ascaris lumbricoides. Neighborhoods of Turbaco had sandy dry soil with low content of ions, low conductivity and low organic matter. Conclusion This study showed a low frequency of intestinal parasites in feces and soils. Despite this, pathogenic parasites were found which can affect the health of the population. Besides this, a high percentage of intestinal parasites that are transmitted through feces were detected indicating fecal contamination and low level of hygiene.

Spatial Distribution of Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Soils from Bursa, Turkey.

PubMed

Karaca, Gizem

2016-02-01

The objectives of this study were to identify regional variations in soil polycyclic aromatic hydrocarbon (PAH) contamination in Bursa, Turkey, and to determine the distributions and sources of various PAH species and their possible sources. Surface soil samples were collected from 20 different locations. The PAH concentrations in soil samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The total PAH concentrations (∑12 PAH) varied spatially between 8 and 4970 ng/g dry matter (DM). The highest concentrations were measured in soils taken from traffic+barbecue+ residential areas (4970 ng/g DM) and areas with cement (4382 ng/g DM) and iron-steel (4000 ng/g DM) factories. In addition, the amounts of ∑7 carcinogenic PAH ranged from 1 to 3684 ng/g DM, and between 5 and 74 % of the total PAHs consisted of such compounds. Overall, 4-ring PAH compounds (Fl, Pyr, BaA and Chr) were dominant in the soil samples, with 29-82 % of the ∑12 PAH consisting of 4-ring PAH compounds. The ∑12 BaPeq values ranged from 0.1 to 381.8 ng/g DM. Following an evaluation of the molecular diagnostic ratios, it was concluded that the PAH pollution in Bursa soil was related to pyrolytic sources; however, the impact of petrogenic sources should not be ignored.

Differential response of ammonia-oxidizing archaea and bacteria to the wetting of salty arid soil.

PubMed

Sher, Yonatan; Ronen, Zeev; Nejidat, Ali

2016-08-01

Ammonia-oxidizing archaea and bacteria (AOA, AOB) catalyze the first and rate-limiting step of nitrification. To examine their differential responses to the wetting of dry and salty arid soil, AOA and AOB amoA genes (encoding subunit A of the ammonia monooxygenase) and transcripts were enumerated in dry (summer) and wet (after the first rainfall) soil under the canopy of halophytic shrubs and between the shrubs. AOA and AOB were more abundant under shrub canopies than between shrubs in both the dry and wetted soil. Soil wetting caused a significant decrease in AOB abundance under the canopy and an increase of AOA between the shrubs. The abundance of the archaeal amoA gene transcript was similar for both the wet and dry soil, and the transcript-to-gene ratios were < 1 independent of niche or water content. In contrast, the bacterial amoA transcript-to-gene ratios were between 78 and 514. The lowest ratio was in dry soil under the canopy and the highest in the soil between the shrubs. The results suggest that the AOA are more resilient to stress conditions and maintain a basic activity in arid ecosystems, while the AOB are more responsive to changes in the biotic and abiotic conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel method for soil aggregate stability measurement by laser granulometry with sonication

NASA Astrophysics Data System (ADS)

Rawlins, B. G.; Lark, R. M.; Wragg, J.

2012-04-01

Regulatory authorities need to establish rapid, cost-effective methods to measure soil physical indicators - such as aggregate stability - which can be applied to large numbers of soil samples to detect changes of soil quality through monitoring. Limitations of sieve-based methods to measure the stability of soil macro-aggregates include: i) the mass of stable aggregates is measured, only for a few, discrete sieve/size fractions, ii) no account is taken of the fundamental particle size distribution of the sub-sampled material, and iii) they are labour intensive. These limitations could be overcome by measurements with a Laser Granulometer (LG) instrument, but this technology has not been widely applied to the quantification of aggregate stability of soils. We present a novel method to quantify macro-aggregate (1-2 mm) stability. We measure the difference between the mean weight diameter (MWD; μm) of aggregates that are stable in circulating water of low ionic strength, and the MWD of the fundamental particles of the soil to which these aggregates are reduced by sonication. The suspension is circulated rapidly through a LG analytical cell from a connected vessel for ten seconds; during this period hydrodynamic forces associated with the circulating water lead to the destruction of unstable aggregates. The MWD of stable aggregates is then measured by LG. In the next step, the aggregates - which are kept in the vessel at a minimal water circulation speed - are subject to sonication (18W for ten minutes) so the vast majority of the sample is broken down into its fundamental particles. The suspension is then recirculated rapidly through the LG and the MWD measured again. We refer to the difference between these two measurements as disaggregation reduction (DR) - the reduction in MWD on disaggregation by sonication. Soil types with more stable aggregates have larger values of DR. The stable aggregates - which are resistant to both slaking and mechanical breakdown by the hydrodynamic forces during circulation - are disrupted only by sonication. We used this method to compare macro-aggregate (1-2 mm) stability of air-dried agricultural topsoils under conventional tillage developed from two contrasting parent material types and compared the results with an alternative sieve-based technique. The first soil from the Midlands of England (developed from sedimentary mudstone; mean soil organic carbon (SOC) 2.5%) contained a substantially larger amount of illite/smectite (I/S) minerals compared to the second from the Wensum catchment in eastern England (developed from sands and glacial deposits; mean SOC=1.7%). The latter soils are prone to large erosive losses of fine sediment. Both sets of samples had been stored air-dried for 6 months prior to aggregate analyses. The mean values of DR (n=10 repeated subsample analyses) for the Midlands soil was 178μm; mean DR (n=10 repeat subsample analyses) for the Wensum soil was 30μm. The large difference in DR is most likely due to differences in soil mineralogy. The coefficient of variation of mean DR for duplicate analyses of sub-samples from the two topsoil types is around 10%. The majority of this variation is likely to be related to the difference in composition of the sub-samples. A standard, aggregated material could be included in further analyses to determine the relative magnitude of sub-sampling and analytical variance for this measurement technique. We then used the technique to investigate whether - as previously observed - variations (range 1000 - 4000 mg kg-1) in the quantity of amorphous (oxalate extractable) iron oxyhydroxides in a variety of soil samples (n=30) from the Wensum area (range SOC 1 - 2%) could account for differences in aggregate stability of these samples.

Distribution of biomass and nutrients in lodgepole pine/bitterbrush ecosystems in central Oregon.

Treesearch

Susan N. Little; Laurl J. Shainsky

1992-01-01

We investigated the distribution of biomass and nutrients in lodgepole pine (Pinus contorta var. murryana Dougl.) ecosystems on pumice soils in south-central Oregon. Sixty-three trees were sampled to develop equations for estimating dry weights of tree crowns, boles, bark, and coarse roots from diameter at breast height and...

Source to Sink Transport of Terrestrial Biomarkers in a Monsoon-driven Fluvial System

NASA Astrophysics Data System (ADS)

Kirkels, F.; Zwart, H. M.; Usman, M.; Basu, S.; Martes, C.; Eglinton, T. I.; Peterse, F.

2016-12-01

Rivers are an important link in global organic carbon (OC) cycling by connecting soils and marine sediments. Whereas deposition of terrestrial carbon in marine settings may form a large OC sink, the extent of OC loss during river transport by CO2 outgassing is highly uncertain. In this context, it is crucial to better constrain the composition and sources of OC in rivers. The Godavari River in Central India is very dynamic with intense rainfall and high soil erosion rates during the monsoon and low transport during the dry period, representative of low frequency, high-impact erosion events expected worldwide due to climate change. In this study, we did a high-resolution sampling of soils, river sediments (bulk and < 63 um) and suspended particulate matter (SPM) during the monsoon and dry season. Source-to-sink tracing of concentration and compositional variations in branched glycerol dialkyl glycerol tetraethers (brGDGTs) as soil-specific biomarkers allowed us to follow soil OC transport through the river basin. Spatial trends in weight-normalized GDGT patterns reveal marked changes during the monsoon and dry season from upstream tributaries towards the delta. Evolution of GDGT signatures along the course of the river shows that SPM during the monsoon carries a primarily soil-derived signal contributed by the northern headwaters. Dominance of the recently discovered 6-methyl isomer indicates a year-round aquatic contribution from the western tributaries. River water isotopic composition and GDGT signatures show that northern tributaries dominate modern OC export from the Godavari basin, providing new information for the interpretation of paleorecords derived from cores taken in the Bay of Bengal. More detailed insights in OC sources in the Godavari basin will derive from (bulk) δ13C and ultimately 14C analyses of soils and river sediments. Further research into provenance of the mineral fraction will reveal if sediment and OC transport is (de)coupled.

Soil greenhouse gas flux, soil moisture, and soil temperature variability among three plant communities from 2015 to 2017 in a High-Arctic lake basin, Northwest Greenland

NASA Astrophysics Data System (ADS)

Konkel, J. M.; Welker, J. M.; Schaeffer, S. M.

2017-12-01

Soil greenhouse gas flux rates are known to vary with plant community and soil environment. Increases in temperature and precipitation are likely to affect the distribution of vegetation and soil conditions in High Arctic ecosystems. In coastal tundra landscapes in northwest Greenland, vegetation, soil organic matter, and greenhouse gas fluxes are thought to be controlled primarily by water availability. In this study, we measured greenhouse gas flux rates, soil moisture, and soil temperature over three summer seasons along a soil moisture gradient in a High Arctic lake basin represented by dry tundra, moist tundra, and wet grassland plant communities. Preliminary results for trace gas fluxes showed N2O production from all three plant communities ranged from 0.03±0.03 to 0.48±0.12 g N ha-1d-1. While wet grassland was a CH4 source up to 5.2±1.1 g C ha-1d-1, dry tundra and moist tundra were CH4 sinks up to -10.4±1.7 and -2.2±0.9 g C ha-1d-1, respectively. For all three seasons, the highest and lowest mean soil CO2 flux rates were measured in wet grassland and moist tundra (up to 18.3±1.1 and 8.7±0.6 kg C ha-1 d-1, respectively). A lab incubation study showed that, with frequent wetting events, soil CO2 flux remained relatively high in wet grassland, was consistently higher in dry tundra than in moist tundra, and dry tundra CO2 flux significantly increased with wetting events. We show that while soil CO2 flux in all three vegetation zones was influenced by soil moisture variability, soil temperature clearly influenced the timing of flux rate increases and decreases over the course of each season. Colder air and soil temperatures in 2017 corresponded with decreased mean soil CO2 flux rates in dry tundra and wet grassland, yet CO2 flux rates remained consistent in moist tundra among all three seasons. These results suggest that climate-induced warmer and wetter soil environmental conditions may increase rates of soil CO2 flux from wet grassland and dry tundra. Further, changes in the distribution of plant communities under future climate scenarios may significantly alter the function of High Arctic lake basins as CH4 sinks or sources, which will be dependent upon the ground area of wet grassland relative to that of dry tundra and moist tundra.

Ash effects on the thermal conductivity of a mediterranean loam soil

NASA Astrophysics Data System (ADS)

Rubio, Carles; Pereira, Paulo; Ubeda, Xavier

2014-05-01

The purpose of this work is to explore the variability on the soil thermal conductivity for a burnt soil and assessing the effects of the ashes on the heat transfer when they were incorporated into the soil matrix. A set of 42 soil samples from the Montgrí massif experimental plot between surface and 5 cm depth was collected before and after the soil was burnt. A thermal characterization of the soil was carried out. For that a dry out curve was constructed, which presented the relationship between water content and thermal conductivity for both types of soil samples, burnt and non-burnt soil. The results shown changes in the heat pulse transfer, being more conductive the soil before to be burnt (0.378 W•m-1•C-1) than the soil after to be exposed to the fire (0.337 W•m-1•C-1). Indeed, on the whole of moisture scenarios the values of thermal conductivity decreased after soil was burnt. Another experimental concern was based on to observe the soil thermal behaviour when ash collected after fire was incorporated into the burnt soil matrix. In this case, soil thermal and soil hydrodynamic behaviour presented differences according to the type of ash. Soil mixed with fly ash showed higher thermal conductivity than soil mixed with bottom ash. To sum up; the soil thermal conductivity decreased when soil was burnt. On the other hand, soil thermal conductivity shown differences depending on the type of ash incorporated into the matrix. Fly ash transferred the heat pulse better than bottom ash.

Nuclear thermal source transfer unit, post-blast soil sample drying system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiser, Ralph S.; Valencia, Matthew J

Los Alamos National Laboratory states that its mission is “To solve national security challenges through scientific excellence.” The Science Undergraduate Laboratory Internship (SULI) programs exists to engage undergraduate students in STEM work by providing opportunity to work at DOE facilities. As an undergraduate mechanical engineering intern under the SULI program at Los Alamos during the fall semester of 2016, I had the opportunity to contribute to the mission of the Laboratory while developing skills in a STEM discipline. I worked with Technology Applications, an engineering group that supports non-proliferation, counter terrorism, and emergency response missions. This group specializes in toolmore » design, weapons engineering, rapid prototyping, and mission training. I assisted with two major projects during my appointment Los Alamos. The first was a thermal source transportation unit, intended to safely contain a nuclear thermal source during transit. The second was a soil drying unit for use in nuclear postblast field sample collection. These projects have given me invaluable experience working alongside a team of professional engineers. Skills developed include modeling, simulation, group design, product and system design, and product testing.« less

Mineralization of carbon and nitrogen from freeze- and over-dried plant material added to soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moorhead, K.K.; Graetz, D.A.; Reddy, K.R.

Drying organic material before soil incorporation is a common procedure used in mineralization or decomposition studies. A laboratory study was conducted to determine the effect of drying methods on plant C and N and associated mineralization patterns in soil. Freeze- and oven-dried water hyacinth (Eichhornia crassipes (Mart) Solms) was added to a Kendrick soil (loamy, siliceous, hyperthermic Arenic Paleudults) at a rate of 5 g kg{sup {minus}1} and incubated in the dark at 27{degree}C for 90 d. Oven drying in paper bags significantly increased the lignin content and decreased the mineral content of the plant material compared to freeze drying.more » The total C and N was not significantly different for the two materials. The mineralization of C from freeze-dried plant material was more rapid during the initial stage of decomposition and remained significantly higher throughout the incubation. At 90 d, 50, and 41% of the plant C had evolved as CO{sub 2} for the freeze- and oven-dried plant material, respectively. Mineralization of {sup 15}N from the plant material accounted for 33% of the applied N of the freeze-dried material and 23% of the applied N of the oven-dried material. Nitrogen mineralization and CO{sub 2} evolution were linearly correlated (r=0.998) for the oven-dried plant material, but less correlated (r=0.770) for the freeze-dried material.« less

Uncovering the effects of Arundo invasion & forest restoration on riparian soils: Plant controls on microbial processes & trace gas flux in a California watershed

NASA Astrophysics Data System (ADS)

Dowdy, K. L.; Dudley, T.; Schimel, J.

2016-12-01

The opportunistic reed Arundo donax has invaded riparian zones in many California watersheds, altering hydrological and ecological processes. There have been intense efforts to restore these watersheds to native vegetation. How the shifts in communities—native to invaded to restored—affect soil conditions and processes, however, remains unclear. Because riparian zones are hotspots of nutrient cycling and greenhouse gas flux, it is critical to understand how plant community composition (and associated litter contributions) governs riparian biogeochemistry. How do organic matter inputs in invaded and restored plant communities alter soil microbial processes and trace gas dynamics? In this study, we use laboratory incubations to compare microbial cycling of C and nitrogen (N) and trace gas flux between the soils and litter of the invasive Arundo and three native riparian species: Populus tricocarpa, Salix laevigata, and Baccharis salicifolia (or, black cotton wood, red willow, and mulefat). Soils beneath Arundo and Salix produced CO2 at a similar rate ( 250 ug CO2 g dry soil-1 hour-1), while Populus and Baccharis produced less ( 170 ug CO2 g dry soil-1 hour-1). All soils consumed CH4; however, Arundo soils consumed more than native-restored species, which consumed similar quantities (-0.013 CH4 g dry soil-1 hour-1 in Arundo vs. -0.009 CH4 g dry soil-1 hour-1 in native). Arundo soils also produced less N2O (0.02 ug N2O g dry soil-1 hour-1) than all native species ( 0.09 ug N2O g dry soil-1 hour-1). Arundo contributed far less litter inputs than native-restored species, as Arundo leaves senesce and remain on the stalk; furthermore, Arundo litter has been shown to have a higher C:N (40.2) than Salix and Baccharis (30.9). Greater CH4 consumption and lower N2O production in Arundo soils may be the result of enhanced porosity compared to restored soils, leading to more aeration and less methanogenesis and denitrification, or it may be that there is lower N availability in Arundo soils suppressing nitrification and reducing NH4- inhibition of methanotrophs.

Impact of biochar amendment on soil water soluble carbon in the context of extreme hydrological events.

PubMed

Wang, Daoyuan; Griffin, Deirdre E; Parikh, Sanjai J; Scow, Kate M

2016-10-01

Biochar amendments to soil have been promoted as a low cost carbon (C) sequestration strategy as well as a way to increase nutrient retention and remediate contaminants. If biochar is to become part of a long-term management strategy, it is important to consider its positive and negative impacts, and their trade-offs, on soil organic matter (SOM) and soluble C under different hydrological conditions such as prolonged drought or frequent wet-dry cycles. A 52-week incubation experiment measuring the influence of biochar on soil water soluble C under different soil moisture conditions (wet, dry, or wet-dry cycles) indicated that, in general, dry and wet-dry cycles increased water soluble C, and biochar addition further increased release of water soluble C from native SOM. Biochar amendment appeared to increase transformation of native SOM to water soluble C, based on specific ultraviolet absorption (SUVA) and C stable isotope composition; however, the increased amount of water soluble C from native SOM is less than 1% of total biochar C. The impacts of biochar on water soluble C need to be carefully considered when applying biochar to agricultural soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Differences on nitrogen availability in a soil amended with fresh, composted and thermally-dried sewage sludge.

PubMed

Tarrasón, D; Ojeda, G; Ortiz, O; Alcañiz, J M

2008-01-01

Anaerobically-digested sludge called fresh sludge (F), composted sludge (C) and thermally-drying sludge (T), all from the same batch, were applied to the surface of a calcareous Udic Calciustept with loamy texture. Dosage equivalent was 10 t ha(-1) of dry matter. The concentration of mineral nitrogen (ammonium and nitrate) in the soil was measured in order to estimate the effects of the post-treatments to which the different kinds of sewage sludge are subjected in relation to the availability of N in the surface layer of the soil. The most significant differences in NH(4)-N and NO(3)-N concentrations due to the transformation of the organic matter were observed during the first three weeks following soil amendment. Thermally-dried and composted sludge initially displayed higher concentrations of ammonium and nitrate in soil. Five months after the amendment, soil applied with fresh sludge showed the highest concentrations of NH(4)-N and NO(3)-N (6.1 and 36.6 mg kg(-1), respectively). It is clear that the processes of composting and thermal-drying influence the bioavailability of nitrogen from the different types of sewage sludge.

Controls of Soil Spatial Variability in a Dry Tropical Forest.

PubMed

Pulla, Sandeep; Riotte, Jean; Suresh, H S; Dattaraja, H S; Sukumar, Raman

2016-01-01

We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km2) soil spatial variability in a seasonally dry tropical forest (SDTF) in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10 cm), rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3(-)-N nor NH4(+)-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief.

Distributions of polycyclic aromatic hydrocarbons in surface waters, sediments and soils of Hangzhou City, China.

PubMed

Chen, Baoliang; Xuan, Xiaodong; Zhu, Lizhong; Wang, Jing; Gao, Yanzheng; Yang, Kun; Shen, Xueyou; Lou, Baofeng

2004-09-01

Ten polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in 17 surface water samples and 11 sediments of four water bodies, and 3 soils near the water-body bank in Hangzhou, China in December 2002. It was observed that the sum of PAHs concentrations ranged from 0.989 to 9.663 microg/L in surface waters, from 132.7 to 7343 ng/g dry weight in sediments, and from 59.71 to 615.8 ng/g dry weight in soils. The composition pattern of PAHs by ring size in water, sediment and soil were surveyed. Three-ring PAHs were dominated in surface waters and soils, meanwhile sediments were mostly dominated by four-ring PAHs. Furthermore, PAHs apparent distribution coefficients (K(d)) and solid f(oc)-normalized K(d) (e.g. K(oc)= K(d) / f(oc)) were calculated. The relationship between logK(oc) and logK(ow) of PAHs for field data on sediments and predicted values were compared. The sources of PAHs in different water bodies were evaluated by comparison of K (oc) values in sediments of the river downstream with that in soils. Hangzhou section of the Great Canal was heavily polluted by PAHs released from industrial wastewater in the past and now PAHs in sediment may serve as sources of PAHs in surface water. PAHs in Qiantang River were contributed from soil runoff. Municipal road runoff was mostly contributed to West Lake PAHs.

Acid-base properties of humic substances from composted and thermally-dried sewage sludges and amended soils as determined by potentiometric titration and the NICA-Donnan model.

PubMed

Fernández, José M; Plaza, César; Senesi, Nicola; Polo, Alfredo

2007-09-01

The acid-base properties of humic acids (HAs) and fulvic acids (FAs) isolated from composted sewage sludge (CS), thermally-dried sewage sludge (TS), soils amended with either CS or TS at a rate of 80 t ha(-1)y(-1) for 3y and the corresponding unamended soil were investigated by use of potentiometric titrations. The non-ideal competitive adsorption (NICA)-Donnan model for a bimodal distribution of proton binding sites was fitted to titration data by use of a least-squares minimization method. The main fitting parameters of the NICA-Donnan model obtained for each HA and FA sample included site densities, median affinity constants and widths of affinity distributions for proton binding to low and high affinity sites, which were assumed to be, respectively, carboxylic- and phenolic-type groups. With respect to unamended soil HA and FA, the HAs and FAs from CS, and especially TS, were characterized by smaller acidic functional group contents, larger proton binding affinities of both carboxylic- and phenolic-type groups, and smaller heterogeneity of carboxylic and phenolic-type groups. Amendment with CS or TS led to a decrease of acidic functional group contents and a slight increase of proton binding affinities of carboxylic- and phenolic-type groups of soil HAs and FAs. These effects were more evident in the HA and FA fractions from CS-amended soil than in those from TS-amended soil.

Controls of Soil Spatial Variability in a Dry Tropical Forest

PubMed Central

Pulla, Sandeep; Riotte, Jean; Suresh, H. S.; Dattaraja, H. S.; Sukumar, Raman

2016-01-01

We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km2) soil spatial variability in a seasonally dry tropical forest (SDTF) in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10cm), rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3−-N nor NH4+-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief. PMID:27100088

[Spatiotemporal variation characteristics of heavy metals pollution in the water, soil and sediments environment of the Lean River-Poyang Lake Wetland].

PubMed

Jian, Min-Fei; Li, Ling-Yu; Xu, Peng-Fei; Chen, Pu-Qing; Xiong, Jian-Qiu; Zhou, Xue-Ling

2014-05-01

Overlying water, sediments, surface soils in the typical wetland areas of Lean River and Poyang Lake which were rich in non-ferrous metal mineral resources on both sides of the river, were chosen for monitoring heavy metals including copper, lead and cadmium of base flow in average season, flood season, and dry season in 2012. Statistical analysis methods were coupled to characterize the spatiotemporal variation of heavy metals pollution and identify the main sources. The results indicated that the concentrations of copper were the highest in all samples of each sampling sites in the Lean River-Poyang Lake wetland. And the content values of copper, lead and cadmium in different samples of different sampling sites also showed that the content values of copper were higher than those of lead, and the content values of lead were also higher than those of cadmium. The results also showed that the heavy metals pollution of copper, lead and cadmium in flood season was the heaviest whereas the heavy metals pollution in dry season was comparatively light. The results of the contents of the three kinds of heavy metals elements in different sampling sites of the watersheds of lean River showed that the contents of copper in the samples from the upstream sampling sites of Lean River were higher than those of other samples from other sites. And the contents of lead in the samples from the downstream sampling sites of Lean River were higher than those of other samples from other sampling sites. The contents of cadmium in the samples from the midstream sampling sites of Lean River were higher than those of other samples from other sites. The first principal component representing copper pollution explained 36. 99% of the total variance of water quality. The second principal component concerning representing lead pollution explained 30. 12% of the total variance. The correlation analysis results showed that there were significant positive correlations among the contents of copper in sediments and the contents of copper in overlying water. And there was also significant positive correlation between the contents of copper in sediments and the contents of copper in the surface soils. And the correlation analysis showed that there were significant positive correlations among the contents of cadmium in sediments and the contents of cadmium in surface soils. The above results reflected that the copper pollution or cadmium sources of water, soil and sediments were consistent, which were mainly from heavy metal acidic waste of mining emissions. The correlations between other components were not very obvious, which reflected the sources of pollutants were different.

Controls on the distribution of productivity and organic resources in Antarctic Dry Valley soils.

PubMed

Hopkins, D W; Sparrow, A D; Novis, P M; Gregorich, E G; Elberling, B; Greenfield, L G

2006-11-07

The Antarctic Dry Valleys are regarded as one of the harshest terrestrial habitats on Earth because of the extremely cold and dry conditions. Despite the extreme environment and scarcity of conspicuous primary producers, the soils contain organic carbon and heterotrophic micro-organisms and invertebrates. Potential sources of organic compounds to sustain soil organisms include in situ primary production by micro-organisms and mosses, spatial subsidies from lacustrine and marine-derived detritus, and temporal subsidies ('legacies') from ancient lake deposits. The contributions from these sources at different sites are likely to be influenced by local environmental conditions, especially soil moisture content, position in the landscape in relation to lake level oscillations and legacies from previous geomorphic processes. Here we review the abiotic factors that influence biological activity in Dry Valley soils and present a conceptual model that summarizes mechanisms leading to organic resources therein.

Short and Long-Term Soil Moisture Effects of Liana Removal in a Seasonally Moist Tropical Forest

PubMed Central

Reid, Joseph Pignatello; Schnitzer, Stefan A.; Powers, Jennifer S.

2015-01-01

Lianas (woody vines) are particularly abundant in tropical forests, and their abundance is increasing in the neotropics. Lianas can compete intensely with trees for above- and belowground resources, including water. As tropical forests experience longer and more intense dry seasons, competition for water is likely to intensify. However, we lack an understanding of how liana abundance affects soil moisture and hence competition with trees for water in tropical forests. To address this critical knowledge gap, we conducted a large-scale liana removal experiment in a seasonal tropical moist forest in central Panama. We monitored shallow and deep soil moisture over the course of three years to assess the effects of lianas in eight 0.64 ha removal plots and eight control plots. Liana removal caused short-term effects in surface soils. Surface soils (10 cm depth) in removal plots dried more slowly during dry periods and accumulated water more slowly after rainfall events. These effects disappeared within four months of the removal treatment. In deeper soils (40 cm depth), liana removal resulted in a multi-year trend towards 5–25% higher soil moisture during the dry seasons with the largest significant effects occurring in the dry season of the third year following treatment. Liana removal did not affect surface soil temperature. Multiple and mutually occurring mechanisms may be responsible for the effects of liana removal on soil moisture, including competition with trees, and altered microclimate, and soil structure. These results indicate that lianas influence hydrologic processes, which may affect tree community dynamics and forest carbon cycling. PMID:26545205

Physical and ecological controllers of the microbial responses to drying and rewetting in soil

NASA Astrophysics Data System (ADS)

Leizeaga, Ainara; Meisner, Annelein; Bååth, Erland; Rousk, Johannes

2017-04-01

Soil moisture is one of the most powerful factors that regulate microbial activity in soil. The variation of moisture leads to drying-rewetting (DRW) events which are known to induce enormous dynamics in soil biogeochemistry; however, the microbial underpinnings are mostly unknown. Rewetting a dry soil can result in two response patterns of bacterial growth. In the Type 1 response, bacteria start growing immediately after rewetting with rates that increase in a linear fashion to converge with those prior to the DRW within hours. This growth response coincides with respiration rates that peak immediately after rewetting to then exponentially decrease. In the Type 2 response, bacterial growth remains very low after rewetting during a lag period of up to 20 hours. Bacteria then increase their growth rates exponentially to much higher rates than those before the DRW event. This growth response coincides with respiration rates that increase to high rates immediately after rewetting that then remain elevated and sometimes even increase further in sync with the growth increase. Previous studies have shown that (i) extended drying (ii) starving before DRW and (iii) inhibitors combined with drought could change the bacterial response from Type 1 to Type 2. This suggested that the response of bacteria upon rewetting could be related to the harshness of the disturbance as experienced by the microbes. In the present study, we set out to study if reduced harshness could change a Type 2 response into a Type 1 response. We hypothesized that (1) a reduced physical harshness of drying and (2) induced tolerance to drying in microbial communities could change a Type 2 response into a Type 1 growth response upon rewetting. To address this, two experiments were performed. First, soils were partially dried to different water contents and bacterial response upon rewetting was measured. Second, soils were exposed to repeated DRW cycles (< 9 cycles) and the bacterial response was followed after rewetting. A less harsh drying (partial drying) of a soil could change the growth responses to rewetting. The lag period decreased with less complete drying to eventually became 0, transitioning from a Type 2 to a Type 1. Even after a Type 1 response was induced, further reduction of harshness could also lead to a faster recovery of growth rates. Our results support the hypothesis: the physical harshness of drying can determine the microbial survival and thus the type of bacterial growth response. Subjecting soil to DRW cycles could also induce a change from a Type 2 to Type 1 growth response. This suggested that there was a community shift towards higher drought-tolerance. Thus, identical physical disturbance was less harsh for a community that has been subjected to more drying rewetting cycles. To predict how the microbial community's control of the soil C budget of ecosystems is affected warming-induced drought, our results demonstrate that both the physical characteristics of the disturbance and the community's tolerance to drought need to be considered.

Effects of biochars on hydraulic properties of clayey soil

NASA Astrophysics Data System (ADS)

Zhen, Jingbo; Palladino, Mario; Lazarovitch, Naftali; Bonanomi, Giuliano; Battista Chirico, Giovanni

2017-04-01

Biochar has gained popularity as an amendment to improve soil hydraulic properties. Since biochar properties depend on feedstocks and pyrolysis temperatures used for its production, proper selection of biochar type as soil amendment is of great importance for soil hydraulic properties improvement. This study investigated the effects of eight types of biochar on physical and hydraulic properties of clayey soil. Biochars were derived from four different feedstocks (Alfalfa hay, municipal organic waste, corn residues and wood chip) pyrolyzed at two different temperatures (300 and 550 °C). Clayey soil samples were taken from Leone farm (40° 26' 15.31" N, 14° 59' 45.54" E), Italy, and were oven-dried at 105 °C to determine dry bulk density. Biochars were mixed with the clayey soil at 5% by mass. Bulk densities of the mixtures were also determined. Saturated hydraulic conductivities (Ks) of the original clayey soil and corresponding mixtures were measured by means of falling-head method. Soil water retention measurements were conducted for clayey soil and mixtures using suction table apparatus and Richards' plate with the pressure head (h) up to 12000 cm. van Genuchten retention function was selected to evaluate the retention characteristics of clayey soil and mixtures. Available water content (AWC) was calculated by field capacity (h = - 500 cm) minus wilting pointing (h = -12000 cm). The results showed that biochar addition decreased the bulk density of clayey soil. The Ks of clayey soil increased due to the incorporation of biochars except for waste and corn biochars pyrolyzed at 550 °C. AWC of soils mixed with corn biochar pyrolyzed at 300 °C and wood biochar pyrolyzed at 550 °C, increased by 31% and 7%, respectively. Further analysis will be conducted in combination of biochar properties such as specific surface area and total pore volume. Better understanding of biochar impact on clayey soil will be helpful in biochar selection for soil amendment and improving water use efficiency in agriculture.

Diapause in copepods (Crustacea) from ephemeral habitats with different hydroperiods in Everglades National Park (Florida, U.S.A.)

USGS Publications Warehouse

Bruno, M.C.; Loftus, W.F.; Reid, J.W.; Perry, S.A.

2001-01-01

Water management practices in the Everglades have severely stressed the natural system, particularly by reducing the hydroperiods of much of the region. During the dry season of 1999, we investigated the influence of hydroperiod on the species composition and dormancy patterns of freshwater copepod communities in seasonal wetlands of Everglades National Park, Florida, U.S.A. The habitats were characterized by an annual dry season, from December through June. We sampled at two locations: the Long Pine Key area of the Rocky Glades region (short hydroperiod, ca. 4-5 months), and western Taylor Slough (intermediate hydroperiod, ca. 8-10 months). Both areas have experienced a reduction in natural hydroperiods and an increase in the frequency of dry-down. We collected weekly plankton samples from Rocky Glades solution holes to assess the potential species pool of copepods. To document the taxa capable of surviving dry-down by resting, we performed three immersion trials in which we rehydrated, in laboratory aquaria, sediment patches from solution holes and surface soils from all stations. Only a subset of the planktonic species collected emerged from the dried sediments. The cyclopoids Microcyclops rubellus and Paracyclops poppei were dominant. This is the first record of diapause for P. poppei. Species distributions from the different hydroperiod soil patches indicated that more diapausing species occurred at the sites that dried for shorter periods. Emerging individuals of M. rubellus and P. poppei were mainly ovigerous females, demonstrating a resting strategy seldom before recorded. The cyclopoid Diacyclops nearcticus had not been previously reported to diapause, but they emerged from the dried sediments in our trials. Our collections included six new records for Florida: Diacyclops nearcticus, Megacyclops latipes, Orthocyclops modestus, Elaphoidella marjoryae, Bryocamptus sp. and Bryocamptus cf. newyorkensis. Paracyclops poppei, Macrocyclops fuscus and Arctodiaptomus floridanus are new records for Everglades National Park. Clearly, diapause is an important strategy for the persistence of copepods in short-hydroperiod wetlands. The duration of the dry period appears to be inversely related to the number of species that emerge from diapause.

Heavy metal speciation and risk assessment in dry land and paddy soils near mining areas at Southern China.

PubMed

Liu, Guannan; Wang, Juan; Zhang, Erxi; Hou, Jing; Liu, Xinhui

2016-05-01

Heavy metal contamination of soils has been a long-standing environmental problem in many parts of the world, and poses enormous threats to ecosystem and human health. Speciation of heavy metals in soils is crucial to assessing environmental risks from contaminated soils. In this study, total concentrations and speciation of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were measured for agricultural soils near mines along the Diaojiang River in Guangxi Zhuang Autonomy Region, China. The sources of heavy metals in soils also were identified to assess their effect on speciation distribution of soil heavy metals. Furthermore, the speciation distribution of Cd and Zn, main soil heavy metal pollutants, in dry land and paddy soils were compared. Results showed that there were two severely polluted regions near mine area reaching alarming pollution level. As, Cd, Pb, and Zn were more affected by mining activities, showing very strong pollution level in soils. The mean percentage of exchangeable and carbonate fraction was highest and up to 46.8 % for Cd, indicating a high environmental risk. Greater bioavailable fractions of As, Cd, Cu, Mn, Pb, and Zn were found in soils heavily polluted by mining activities, whereas Cr and Ni as geogenic elements in the stable residual fraction. In addition, in the dry land soils, reducible fraction proportion of Cd was higher than that in the paddy soils, whereas exchangeable and carbonate fraction of Cd was lower than that in the paddy soils. Oxidizable fraction of Zn was higher in the paddy soils than that in the dry land soils. The results indicate that the sources of soil heavy metals and land types affect heavy metal speciation in the soil and are significant for environmental risk assessment of soil heavy metal pollutions.

Effect of biochar addition on short-term N2O and CO2 emissions during repeated drying and wetting of an anthropogenic alluvial soil.

PubMed

Yang, Fang; Lee, Xinqing; Theng, Benny K G; Wang, Bing; Cheng, Jianzhong; Wang, Qian

2017-06-01

Agricultural soils are an important source of greenhouse gases (GHG). Biochar application to such soils has the potential of mitigating global anthropogenic GHG emissions. Under irrigation, the topsoils in arid regions experience repeated drying and wetting during the crop growing season. Biochar incorporation into these soils would change the soil microbial environment and hence affect GHG emissions. Little information, however, is available regarding the effect of biochar addition on carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) emissions from agricultural soils undergoing repeated drying and wetting. Here, we report the results of a 49-day aerobic incubation experiment, incorporating biochar into an anthropogenic alluvial soil in an arid region of Xinjiang Province, China, and measuring CO 2 and N 2 O emissions. Under both drying-wetting and constantly moist conditions, biochar amendment significantly increased cumulative CO 2 emission. At the same time, there was a significant reduction (up to ~20 %) in cumulative N 2 O emission, indicating that the addition of biochar to irrigated agricultural soils may effectively slow down global warming in arid regions of China.

Potential use of fly ash to soil treatment in the Morava region

NASA Astrophysics Data System (ADS)

Bulíková, Lucia; Kresta, František; Rochovanský, Martin

2017-09-01

Soil treatment by binders is a standard technology and leads to optimal utilization of excavated soils in road constructions. Soil treatment is controlled in the Czech Republic by EN 14227-15 and Technical Requirement TP 94. Soil treatment using fly ash has not been performed in the Czech Republic, although there is a sufficient normative base. Fly ash produced by burning of hard coal in the Moravian region was tested as a potential binder. Fly ash samples were mixed with loess loams (CI). Tested siliceous fly ash of class F (ASTM C618) did not showed hydraulic properties but it showed positive effect on reducing maximum dry density of mixtures, increasing the IBI value (Immediate bearing index) and decreasing tendency to volume changes when the amount of fly ash was increased. The results of laboratory tests demonstrate the possibility of using fly ashes as a binder for soil treatment.

The Influence of Processing Soil With a Coffee Grinder on Soil Classification

DTIC Science & Technology

2015-01-20

shaker, sieves , coffee grinder, plastic limit tool, bowls, spatulas, and scoops. To classify soils, a dry sieve analysis is performed, as is a Plastic...processed with the coffee grinder for 90 seconds as described above. Sieve analysis using the wet preparation method was used to test and classify the soils...one 90 second cycle of Elevator Soil Figure 3: The blades after three 90 second cycles of Elevator Soil 71Page 4.2 Ottawa Sand Dry Sieve Analysis

Trees influence preferencial flow and water uptake in tropical savanna

NASA Astrophysics Data System (ADS)

Benegas, Laura; Bargues-Tobella, Aida; Hasselquist, Niles; Malmer, Anders; Ilstedt, Ulrik

2017-04-01

To address potential competition between trees and grasses for soil water, and to disentangle the main process responsible for local soil water dynamics in pasture ecosystems, we conducted a study of the soil water content and water source partitioning of grasses and trees within a pasture in the Copan River catchment, Honduras. We used differences in the 2H/1H (δD) isotopic signature of soil water (δSW) and the local meteoric water line (LMWL; δLMWL) as a relative index of evaporation, following a recent model proposed by Hasselquist et al (under review). The model uses Lc-excess calculated as the absolute value of the difference between measured δD and that predicted by the local meteoric water line (lc-excess = ¦δDM - δDP¦). Lc-excess values close to zero indicate little difference between soil water samples and local precipitation, whereas larger values indicate a greater degree of evaporation .()...(adapted from Landwehr and Coplen, 2006). From the relation between Lc-excess and SWC, we can tease apart different processes by which trees influence local soil water dynamics, where one such processes indicate that if preferential flow, i.e quick flows through macropores that by-pass the soil matrix, is the main pathway for water movement in the soil, then the Lc-excess values of soil water at deeper depths will be closer to zero than those of the surface soil, whereas relatively higher Lc-excess values would indicate increasing dominance of matrix flow. We found that soil underneath trees was wetter than underneath grasses at the dry season and we can relate this with a lack of clear relationship between Lc-excess and SWC and with the treés apparent shift to groundwater sources for root uptake especially in the dry season. Due to the positive correlation between Lc-excess and SWC under trees and due to the lower Lc-excess values found at subsoil below trees during the dry season, we can infer that preferential flow is also facilitated by the trees enhancing its contribution to groundwater recharge. The possible water losses via interception linked with trees on the soil water dynamic was counterbalanced by the positive contribution of trees to preferential flow and groundwater recharge.

Combining airborne laser scanning and Landsat data for statistical modeling of soil carbon and tree biomass in Tanzanian Miombo woodlands.

PubMed

Egberth, Mikael; Nyberg, Gert; Næsset, Erik; Gobakken, Terje; Mauya, Ernest; Malimbwi, Rogers; Katani, Josiah; Chamuya, Nurudin; Bulenga, George; Olsson, Håkan

2017-12-01

Soil carbon and biomass depletion can be used to identify and quantify degraded soils, and by using remote sensing, there is potential to map soil conditions over large areas. Landsat 8 Operational Land Imager satellite data and airborne laser scanning data were evaluated separately and in combination for modeling soil organic carbon, above ground tree biomass and below ground tree biomass. The test site is situated in the Liwale district in southeastern Tanzania and is dominated by Miombo woodlands. Tree data from 15 m radius field-surveyed plots and samples of soil carbon down to a depth of 30 cm were used as reference data for tree biomass and soil carbon estimations. Cross-validated plot level error (RMSE) for predicting soil organic carbon was 28% using only Landsat 8, 26% using laser only, and 23% for the combination of the two. The plot level error for above ground tree biomass was 66% when using only Landsat 8, 50% for laser and 49% for the combination of Landsat 8 and laser data. Results for below ground tree biomass were similar to above ground biomass. Additionally it was found that an early dry season satellite image was preferable for modelling biomass while images from later in the dry season were better for modelling soil carbon. The results show that laser data is superior to Landsat 8 when predicting both soil carbon and biomass above and below ground in landscapes dominated by Miombo woodlands. Furthermore, the combination of laser data and Landsat data were marginally better than using laser data only.

[Parameters optimization and cleaning efficiency evaluation of attrition scrubbing remediation of Pb-contaminated soil].

PubMed

Yang, Wen; Huang, Jin-lou; Peng, Hui-qing; Li, Si-tuo

2013-09-01

Attrition scrubbing was used to remediate lead contaminated-site soil, and the main purpose was to remove fine particles and lead contaminants from the surface of sand. The optimal parameters of attrition scrubbing were determined by orthogonal experiment, and three soil samples with different lead concentration were subjected to attrition scrubbing experiments. The results showed that the optimal scrubbing parameters were: a solid ratio of 70% dry matter, a temperature of 25 degrees C, an attrition time of 30 min, and an attrition speed of 1200 r x min(-1). Before attrition scrubbing, the screening and analysis of soil showed that in all three soil samples, lead was mainly enriched on sand and fine particles, and the distribution of lead was highly correlated to the organic matter. After attrition scrubbing, the washing efficiency of the original state lead contaminated sand soil in triplicates was 67.61%, 31.71% and 41.01%, respectively, which indicates that attrition scrubbing can remove part of the fine soil and lead contaminants from the surface of sand, to accomplish the purpose of pollutants enrichment. Scanning electron microscopy (SEM) analysis showed that the sand surface became smooth after attrition scrubbing. The results above show that attrition scrubbing has a good washing effect for the remediation of lead contaminated sand soil.

Effects of Apollo 12 lunar material on lipid levels of tobacco tissue and slash pine cultures

NASA Technical Reports Server (NTRS)

Weete, J. D.

1972-01-01

Investigations of the lipid components of pine tissues (Pinus elloitii) are discussed, emphasizing fatty acids and steroids. The response by slash pine tissue cultures to growth in contact with Apollo lunar soil, earth basalt, and Iowa soil is studied. Tissue cultures of tobacco grown for 12 weeks in contact with lunar material from Apollo 12 flight contained 21 to 35 percent more total pigment than control tissues. No differences were noted in the fresh or dry weight of the experimental and control samples.

A novel in-situ method for real-time monitoring of gas transport in soil

NASA Astrophysics Data System (ADS)

Laemmel, Thomas; Maier, Martin; Schack-Kirchner, Helmer; Lang, Friederike

2017-04-01

Gas exchange between soil and atmosphere is important for the biogeochemistry of soils. Gas transport in soil is commonly assumed to be governed by molecular diffusion and is usually described by the soil gas diffusion coefficient DS characterizing the ability of the soil to "transport passively" gas through the soil. One way to determine DS is sampling soil cores in the field and measuring DS in the lab. Unfortunately this method is destructive and laborious. Moreover, a few previous field studies identified other gas transport processes in soil to significantly enhance the diffusive gas transport. However, until now, no method is available to measure gas transport in situ in the soil. We developed a novel method to monitor gas transport in soil in situ. The method includes a custom made gas sampling device, the continuous injection of an inert tracer gas and inverse gas transport modelling in the soil. The gas sampling device has several sampling depths and can be easily installed into a vertical hole drilled by an auger, which allows for fast installation of the system. Helium (He) as inert tracer gas was injected continuously at the lower end of the device. The resulting steady state distribution of He was used to deduce the depth profile of DS. Gas transport in the soil surrounding the gas-sampling-device/soil system was modeled using the Finite Element Modeling program COMSOL . We tested our new method both in the lab and during two short field studies and compared the results with a reference method using soil cores. DS profiles obtained by our in-situ method were consistent with DS profiles determined based on soil core analyses. During a longer monitoring field campaign, typical soil-moisture effects upon gas diffusivity such as an increase during a drying period or a decrease after rain could be observed consistently. Under windy conditions we additionally measured for the first time the direct enhancement of gas transport in soil due to wind-induced pressure-pumping which could increase the effective DS up to 30% in the topsoil. Our novel monitoring method can be quickly and easily installed and allows for monitoring continuously soil gas transport over a long time. It allows monitoring physical modifications of soil gas diffusivity due to rain events or evaporation but it also allows studying non-diffusive gas transport processes in the soil.

Advanced microwave soil moisture studies. [Big Sioux River Basin, Iowa

NASA Technical Reports Server (NTRS)

Dalsted, K. J.; Harlan, J. C.

1983-01-01

Comparisons of low level L-band brightness temperature (TB) and thermal infrared (TIR) data as well as the following data sets: soil map and land cover data; direct soil moisture measurement; and a computer generated contour map were statistically evaluated using regression analysis and linear discriminant analysis. Regression analysis of footprint data shows that statistical groupings of ground variables (soil features and land cover) hold promise for qualitative assessment of soil moisture and for reducing variance within the sampling space. Dry conditions appear to be more conductive to producing meaningful statistics than wet conditions. Regression analysis using field averaged TB and TIR data did not approach the higher sq R values obtained using within-field variations. The linear discriminant analysis indicates some capacity to distinguish categories with the results being somewhat better on a field basis than a footprint basis.

Risk element sorption/desorption characteristics of dry olive residue: a technique for the potential immobilization of risk elements in contaminated soils.

PubMed

Hovorka, Miloš; Száková, Jiřina; García-Sánchez, Mercedes; Acebal, Mercedes Blanc; García-Romera, Inmaculada; Tlustoš, Pavel

2016-11-01

Olive oil production is one of the most relevant agroindustrial activities in the Mediterranean region and generates a huge amount of both solid and semi-solid wastes, the uncontrolled disposal of which might lead to serious environmental problems. Due to its organic matter and mineral nutrient content, the waste material can be applied to agricultural soil as a fertilizer. However, due to its high organic matter content, dry olive residue (DOR), commonly called "alperujo," has the potential to immobilize risk elements in contaminated soils. The main objective of this study was to assess the possible effect of DOR on sorption of risk elements such as cadmium (Cd), lead (Pb), and zinc (Zn) in the soil. A set of batch sorption experiments were carried out to assess the ability of DOR to adsorb Cd, Pb, and Zn where the effect of the preceding biotransformation of DOR by four species of fungi: Penicillium chrysogenum, Coriolopsis floccosa, Bjerkhandera adusta, and Chondrostereum purpureum was compared. The Freundlich and Langmuir sorption isotherms were calculated to assess the sorption characteristics of both transformed and non-transformed DOR. The results showed good potential sorption capacity of DOR, especially for Pb and to a lesser extent for Cd and Zn. Better sorption characteristics were reported for the biotransformed DOR samples, which are expected to show higher humification of the organic matter. However, the desorption experiments showed weakness and instability of the DOR-bound elements, especially in the case of Zn. Thus, future research should aim to verify the DOR sorption pattern in contaminated soil as well as the potential stabilization of the DOR element bounds where the increase of the pH levels of the DOR samples needs to be taken into account.

Selenium content of game meat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medeiros, L.C.; Belden, R.P.

Selenium (Se) content of elk, deer, bison and beef were measured and compared. Samples were obtained from animals grazed on soil known to contain high, but variable amounts of Se. Beef were feedlot grazed and elk, deer, and bison were from captive or semi-captive herds. Selenium content was determined by graphite furnace after high pressure wet microwave digestion of samples. Deer and bison contained more Se than elk or beef. On a dry weight basis, deer contained more Se than bison. Game species contained more Se than beef. Within samples from male elk and deer and elk and bison ofmore » both genders, there were interactions between specie and muscle effects. Muscle and gender did not significantly influence Se content. The animals from which these samples were taken were supplemented with feeds grown on high Se containing soils, which was reflected in all values. Se values were twofold higher than those previously reported for meat. Those consuming large quantities of game from areas with high Se soil may need to monitor Se intake to avoid consuming excessive quantities.« less

Abundance and stratification of soil macroarthropods in a Caatinga Forest in Northeast Brazil.

PubMed

Araújo, V F P; Bandeira, A G; Vasconcellos, A

2010-10-01

In arid and semiarid environments, seasonality usually exerts a strong influence on the composition and dynamics of the soil community. The soil macroarthropods were studied in a Caatinga forest located in the Reserva Particular do Patrimônio Natural (RPPN) Fazenda Almas, São José dos Cordeiros, Paraíba, Brazil. Samples were collected during the dry and rainy seasons following the method proposed by the Tropical Soil Biology and Fertility Program (TSBF), with minor modifications. At each station, 15 soil blocks (20 × 20 × 30 cm: 12 L) were extracted and divided into three layers: A (0-10 cm), B (10-20 cm), and C (20-30 cm). In the rainy and dry seasons 1,306 ± 543(se) and 458 ± 212 ind.m-2 macroarthropods were found, respectively, with 35 and 18 respective taxa recorded. The abundance of individuals and taxa were significantly higher in the rainy season. Isoptera (57.8%) was the most abundant taxon, followed by Hymenoptera: Formicidae (17.2%), Coleoptera larvae (7.3%), and Araneae (3.5%). In the rainy season, abundance in layer A (576 ± 138 ind.m-2) was significantly higher than that of layer C (117 ± 64 ind.m-2), but was not different from layer B (613 ± 480 ind.m-2). There was also no difference between the layer B and C abundances. In the dry season, abundance in layer B (232 ± 120 ind.m-2) was not significantly different compared to layer A (182 ± 129 ind.m-2), but was significantly higher than abundance in layer C (44 ± 35 ind.m-2). During the rainy season, layer A (34 taxa) was significantly richer in taxa than layers B (19 taxa) and C (11 taxa). On the other hand, during the dry season the richness of layers A (12 taxa) and B (12 taxa) was equal, but significantly higher than that of layer C (6 taxa). Richness of taxa and abundance were positively correlated with soil organic matter and negatively correlated with soil temperature. The community of soil macroarthropods in the area of Caatinga studied has taxonomic and functional structures that are relatively complex and is therefore likely to exert an influence on ecosystem productivity due to its physical effects on soil profile and necromass fragmentation, as occurs in other arid and semiarid ecosystems throughout the world.

The influence of compost addition on the water repellency of brownfield soils

NASA Astrophysics Data System (ADS)

Whelan, Amii; Kechavarzi, Cedric; Sakrabani, Ruben; Coulon, Frederic; Simmons, Robert; Wu, Guozhong

2010-05-01

Compost application to brownfield sites, which can facilitate the stabilisation and remediation of contaminants whilst providing adequate conditions for plant growth, is seen as an opportunity to divert biodegradable wastes from landfill and put degraded land back into productive use. However, although compost application is thought to improve soil hydraulic functioning, there is a lack of information on the impact of large amounts of compost on soil water repellency. Water repellency in soils is attributed to the accumulation of hydrophobic organic compounds released as root exudates, fungal and microbial by-products and decomposition of organic matter. It has also been shown that brownfield soils contaminated with petroleum-derived organic contaminants can exhibit strong water repellency, preventing the rapid infiltration of water and leading potentially to surface run off and erosion of contaminated soil. However, hydrophobic organic contaminants are known to become sequestrated by partitioning into organic matter or diffusing into nano- and micropores, making them less available over time (ageing). The effect of large amounts of organic matter addition through compost application on the water repellency of soils contaminated with petroleum-derived organic contaminants requires further investigation. We characterised the influence of compost addition on water repellency in the laboratory by measuring the Water Drop Penetration Time (WDPT), sorptivity and water repellency index through infiltration experiments on soil samples amended with two composts made with contrasting feedstocks (green waste and predominantly meat waste). The treatments consisted of a sandy loam, a clay loam and a sandy loam contaminated with diesel fuel and aged for 3 years, which were amended with the two composts at a rate equivalent to 750t/ha. In addition core samples collected from a brownfield site, amended with compost at three different rates (250, 500 and 750t/ha) in 2007, were also tested. The results show that the water repellency of air dried samples is significantly higher in samples amended with composts and increases with increasing organic matter content. The WDPT suggests that compost, when dry, is hydrophobic. Diesel contamination leads to a decrease in sorptivity compared to uncontaminated controls and wettability is not re-established following the addition of compost. Finally, the increase in compost volume (i.e. application rate) in the field samples leads to an increase in water repellency. The infiltration tests, carried out using a miniature tension infiltrometer, also illustrate different effects of hydrophobicity on infiltration, with some samples demonstrating reduced infiltration and low sorptivity but others showing no infiltration at all until the breakdown of repellency at later times. This investigation is currently being complemented by a study of the influence of hydrophobic organic contaminant sequestration with time (i.e. ageing), estimated by measuring the changes in the available fraction of polycyclic aromatic hydrocarbons (PAHs), on the water repellency of compost amended brownfield soils.

Identification of dust storm origin in South -West of Iran.

PubMed

Broomandi, Parya; Dabir, Bahram; Bonakdarpour, Babak; Rashidi, Yousef

2017-01-01

Deserts are the main sources of emitted dust, and are highly responsive to wind erosion. Low content of soil moisture and lack of vegetation cover lead to fine particle's release. One of the semi-arid bare lands in Iran, located in the South-West of Iran in Khoozestan province, was selected to investigate Sand and Dust storm potential. This paper focused on the metrological parameters of the sampling site, their changes and the relationship between these changes and dust storm occurrence, estimation of Reconaissance Drought Index, the Atterberg limits of soil samples and their relation with soil erosion ability, the chemical composition, size distribution of soil and airborne dust samples, and estimation of vertical mass flux by COMSALT through considering the effect of saffman force and interparticle cohesion forces during warm period (April-September) in 2010. The chemical compositions are measured with X-ray fluorescence, Atomic absorption spectrophotometer and X-ray diffraction. The particle size distribution analysis was conducted by using Laser particle size and sieve techniques. There was a strong negative correlation between dust storm occurrence and annual and seasonal rainfall and relative humidity. Positive strong correlation between annual and seasonal maximum temperature and dust storm frequency was seen. Estimation of RDI st in the studied period showed an extremely dry condition. Using the results of particle size distribution and soil consistency, the weak structure of soil was represented. X-ray diffraction analyses of soil and dust samples showed that soil mineralogy was dominated mainly by Quartz and calcite. X-ray fluorescence analyses of samples indicated that the most important major oxide compositions of the soil and airborne dust samples were SiO 2 , Al 2 O 3 , CaO, MgO, Na 2 O, and Fe 2 O 3 , demonstrating similar percentages for soil and dust samples. Estimation of Enrichment Factors for all studied trace elements in soil samples showed Br, Cl, Mo, S, Zn, and Hg with EF values higher than 10. The findings, showed the possible correlation between the degree of anthropogenic soil pollutants, and the remains of Iraq-Iran war. The results expressed sand and dust storm emission potential in this area, was illustrated with measured vertical mass fluxes by COMSALT.

A survey of trace metals in vegetation, soil and lower animal along some selected major roads in metropolitan city of Lagos.

PubMed

Awofolu, O R

2005-06-01

The concentration of trace metals (Cd, Cu, Pb and Zn) in a total of 144 samples of grass, soil and lower animal (earthworm, Lybrodrilus violaceous) were collected and analysed for their metallic content. Levels of cadmium ranged from 0.01-0.07 microg g(-1); 0.01-0.12 microg g(-1) and from trace-0.05 microg g(-1) dry weight for plant, soil and animal samples respectively. Mean concentration of copper ranged 0.10-1.48 microg g(-1); 0.10-2.90 microg g(-1) and 0.01-0.08 microg g(-1) for samples in similar order as above. The levels of Pb varied from 0.01-0.14 microg g(-1); 0.02-0.23 microg g(-1) and from trace-0.07 microg (g-1) while that of Zn ranged from 0.19-1.80 microg g(-1); 0.51-3.35 microg g(-1) and 0.01-0.08 microg g(-1) also in the same order of samples as mentioned above. Levels of metals in soil samples were higher than the background levels with the exception of Zn but lower than European Union (EU) limits. The results generally revealed the presence of metals in plant and animal samples and metal dynamics up the food chain is highly possible. Acceptable recoveries of the spiking experiment validate the experimental protocol.

Heavy metal contamination in the vicinity of an industrial area near Bucharest.

PubMed

Velea, Teodor; Gherghe, Liliana; Predica, Vasile; Krebs, Rolf

2009-08-01

Heavy metals such as lead are well known to cause harmful health effects. Especially children are particularly susceptible to increased levels of lead in their blood. It is also a fact that lead concentration is increasing in the environment due to increased anthropogenic activity. The risk of heavy metal contamination is pronounced in the environment adjacent to large industrial complexes. In a combined case study, the environmental pollution by heavy metals was related to children's health in the vicinity of an industrial area located 4 km south-east from Bucharest about 2 km east from the nearest town-Pantelimon. This site includes companies processing different, nonferrous solid wastes for recovery of heavy metals and producing different nonferrous alloys and lead batteries. In this paper, mainly the results of environmental sampling and analyses are summarized. Water, soil, and atmospheric deposition samples were collected from different locations within 3 km from the industrial area. For comparison, samples were also taken from Bucharest. Water samples were filtered (<0.45 microm), extracted by salpetric acid, and quantified by ICP-OES and ICP-MS. Soil samples were dried, sieved (<2 mm), extracted by aqua regia and analyzed by AAS. In order to quantify the atmospheric deposition, three kinds of permanently open collecting pots were used on nine different sites between August and November 2006. At most sampling locations, the heavy metal concentrations in soil decrease with increasing distance to the presumably major source of pollution. Highest heavy metal concentrations were found in 10-20 cm soil depths. There were also decreasing heavy metal concentrations for atmospheric deposition with increasing distance to the industrial site. In surface and groundwater samples, traces of zinc, copper and lead were detected. The heavy metal concentrations in soil were increased in the study area, mostly under legal action limits in low-concern areas (e.g., 1,000 mg Pb/kg dry soil), but often above action limits for high-concern areas (100 mg Pb/kg dry soil) such as populated areas. The soluble lead concentrations in water samples indicate a need for monitoring and assessing water quality in more detail. The results for atmospheric deposition showed increased dust precipitation and heavy metal loads in the study area compared to Bucharest. However, based on mass flow balance calculations, the actual atmospheric deposition of heavy metals must be much lower than it was in the past decades. It was shown that highest lead values in water, soil and atmospheric deposition are rather to be found near the investigated industrial site than at the control sites in Bucharest. Our results correspond very well with results that show that children from Pantelimon have significantly increased lead concentrations in their blood compared to children in Bucharest. The increased lead contamination around the investigated industrial area is likely to have caused the increased exposure for children living in Pantelimon. In high-concern areas, such as found in populated areas, further measures have to be taken to avoid health risks for people living in these areas. The measures already taken to reduce emissions from the industrial site will help to avoid further increases in heavy metal concentrations. In areas with exceeded action limits, measures have to be taken as required by law. Detailed risk assessments could help to take necessary actions to protect public health in this area. The public should be informed about the potential hazards of eating plants grown in that area. Educational programs for schools, informing children about the contamination, should lead to a better understanding of environmental problems and a more sustainable behavior in the future.

Survey monitoring results on the reduction of micropollutants, bacteria, bacteriophages and TSS in retention soil filters.

PubMed

Tondera, Katharina; Koenen, Stefan; Pinnekamp, Johannes

2013-01-01

A main source of surface water pollution in Western Europe stems from combined sewer overflow. One of the few technologies available to reduce this pollution is the retention soil filter. In this research project, we evaluated the cleaning efficiency of retention soil filters measuring the concentration ratio of standard wastewater parameters and bacteria according to factors limiting efficiency, such as long dry phases or phases of long-lasting retention. Furthermore, we conducted an initial investigation on how well retention soil filters reduce certain micropollutants on large-scale plants. There was little precipitation during the 1-year sampling phase, which led to fewer samples than expected. Nevertheless, we could verify how efficiently retention soil filters clean total suspended solids. Our results show that retention soil filters are not only able to eliminate bacteria, but also to retain some of the micropollutants investigated here. As the filters were able to reduce diclofenac, bisphenol A and metoprolol by a median rate of almost 75%, we think that further investigations should be made into the reduction processes in the filter. At this point, a higher accuracy in the results could be achieved by conducting bench-scale experiments.

DDT, DDD, and DDE in soil of Xiangfen County, China: Residues, sources, spatial distribution, and health risks.

PubMed

Ma, Jin; Pan, Li-Bo; Yang, Xiao-Yang; Liu, Xiao-Ling; Tao, Shi-Yang; Zhao, Long; Qin, Xiao-Peng; Sun, Zai-Jin; Hou, Hong; Zhou, Yong-Zhang

2016-11-01

We collected and analyzed 128 surface soil samples from Xiangfen County for dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE). Total DDT concentrations (DDTs; sum of p,p'-DDD, p,p'-DDE, and p,p'-DDT) ranged from ND to 427.81 ng g(-1) (dry weight, dw), with a mean of 40.26 ng g(-1) (dw). Among the three compounds, p,p'-DDD was the most dominant. The DDTs in Xiangfen County soils mainly originated from historical DDT use, but there were also new inputs likely related to dicofol use. The DDTs in Xiangfen County soils were mainly degraded under anaerobic conditions, and direct degradation to DDD was the main degradation route. Regions with relatively high concentrations of DDTs were mainly located in North and South Xiangfen County. In these regions, many soil samples contained p,p'-DDT as the predominant pollutant, suggestive of extensive new inputs of DDT. A health risk assessment revealed that there are no serious long-term health impacts of exposure to DDTs in soil, for adults or children. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamics of Cd, Cu and Pb added to soil through different kinds of sewage sludge.

PubMed

Torri, S I; Lavado, R S

2008-01-01

A greenhouse experiment was set up to study the distribution of Cd, Cu and Pb in three typical soils of the Pampas Region amended with sewage sludge. A sequential extraction procedure was used to obtain four operationally defined geochemical species: exchangeable, bound to organic matter, bound to carbonates, and residual. Two kinds of sewage sludge were used: pure sewage sludge and sewage sludge containing 30% DM of its own incinerated ash, at rates equivalent to a field application of 150 t DM ha(-1). Pots were maintained at 80% of field capacity through daily irrigation with distilled water. Soil samples were obtained on days 1, 60, 270 and 360, and then air-dried and passed through a 2 mm sieve for analysis. Results showed that sludge application increased the less available forms of Cd, Cu and Pb. The inorganic forms became the most prevalent forms for Cu and Pb, whereas Cd was only found in the residual fraction. The concentrations of OM-Cu and INOR-Cu in the amended soil samples were closely correlated with soil pH, whereas the chemical behavior of Cd and Pb did not depend on soil physico-chemical characteristics.

Mercury in soil and perennial plants in a mining-affected urban area from Northwestern Romania.

PubMed

Senilă, Marin; Levei, Erika A; Senilă, Lăcrimioara R; Oprea, Gabriela M; Roman, Cecilia M

2012-01-01

The mercury (Hg) concentrations were evaluated in soils and perennial plants sampled in four districts of Baia Mare city, a historical mining and ore processing center in Northwestern Romania. The results showed that the Hg concentration exceeded the guideline value of 1.0 mg kg(-1) dry weight (dw) established by the Romanian Legislation, in 24 % of the analyzed soil samples, while the median Hg concentration (0.70 mg kg(-1) dw) was lower than the guideline value. However, Hg content in soil was generally higher than typical values in soils from residential and agricultural areas of the cities all over the world. The median Hg concentration was 0.22 mg kg(-1) dw in the perennial plants, and exceeded the maximum level of Hg (0.10 mg kg(-1)) established by European Directive 2002/32/EC for plants used in animal feed in order to prevent its transfer and further accumulation in the higher levels of food chain. No significant correlations were found between soil Hg and other analyzed metals (Cd, Cu, Pb, Zn) resulted from the non-ferrous smelting activities, probably due to the different physicochemical properties, that led to different dispersion patterns.

Spatial Variability of PAHs and Microbial Community Structure in Surrounding Surficial Soil of Coal-Fired Power Plants in Xuzhou, China

PubMed Central

Ma, Jing; Zhang, Wangyuan; Chen, Yi; Zhang, Shaoliang; Feng, Qiyan; Hou, Huping; Chen, Fu

2016-01-01

This work investigated the spatial profile and source analysis of polycyclic aromatic hydrocarbons (PAHs) in soil that surrounds coal-fired power plants in Xuzhou, China. High-throughput sequencing was employed to investigate the composition and structure of soil bacterial communities. The total concentration of 15 PAHs in the surface soils ranged from 164.87 to 3494.81 μg/kg dry weight. The spatial profile of PAHs was site-specific with a concentration of 1400.09–3494.81 μg/kg in Yaozhuang. Based on the qualitative and principal component analysis results, coal burning and vehicle emission were found to be the main sources of PAHs in the surface soils. The phylogenetic analysis revealed differences in bacterial community compositions among different sampling sites. Proteobacteria was the most abundant phylum, while Acidobacteria was the second most abundant. The orders of Campylobacterales, Desulfobacterales and Hydrogenophilales had the most significant differences in relative abundance among the sampling sites. The redundancy analysis revealed that the differences in bacterial communities could be explained by the organic matter content. They could also be explicated by the acenaphthene concentration with longer arrows. Furthermore, OTUs of Proteobacteria phylum plotted around particular samples were confirmed to have a different composition of Proteobacteria phylum among the sample sites. Evaluating the relationship between soil PAHs concentration and bacterial community composition may provide useful information for the remediation of PAH contaminated sites. PMID:27598188

Spatial Variability of PAHs and Microbial Community Structure in Surrounding Surficial Soil of Coal-Fired Power Plants in Xuzhou, China.

PubMed

Ma, Jing; Zhang, Wangyuan; Chen, Yi; Zhang, Shaoliang; Feng, Qiyan; Hou, Huping; Chen, Fu

2016-09-02

This work investigated the spatial profile and source analysis of polycyclic aromatic hydrocarbons (PAHs) in soil that surrounds coal-fired power plants in Xuzhou, China. High-throughput sequencing was employed to investigate the composition and structure of soil bacterial communities. The total concentration of 15 PAHs in the surface soils ranged from 164.87 to 3494.81 μg/kg dry weight. The spatial profile of PAHs was site-specific with a concentration of 1400.09-3494.81 μg/kg in Yaozhuang. Based on the qualitative and principal component analysis results, coal burning and vehicle emission were found to be the main sources of PAHs in the surface soils. The phylogenetic analysis revealed differences in bacterial community compositions among different sampling sites. Proteobacteria was the most abundant phylum, while Acidobacteria was the second most abundant. The orders of Campylobacterales, Desulfobacterales and Hydrogenophilales had the most significant differences in relative abundance among the sampling sites. The redundancy analysis revealed that the differences in bacterial communities could be explained by the organic matter content. They could also be explicated by the acenaphthene concentration with longer arrows. Furthermore, OTUs of Proteobacteria phylum plotted around particular samples were confirmed to have a different composition of Proteobacteria phylum among the sample sites. Evaluating the relationship between soil PAHs concentration and bacterial community composition may provide useful information for the remediation of PAH contaminated sites.

Roles of Arbuscular Mycorrhizal Fungi and Soil Abiotic Conditions in the Establishment of a Dry Grassland Community.

PubMed

Knappová, Jana; Pánková, Hana; Münzbergová, Zuzana

2016-01-01

The importance of soil biota in the composition of mature plant communities is commonly acknowledged. In contrast, the role of soil biota in the early establishment of new plant communities and their relative importance for soil abiotic conditions are still poorly understood. The aim of this study was to understand the effects of soil origin and soil fungal communities on the composition of a newly established dry grassland plant community. We used soil from two different origins (dry grassland and abandoned field) with different pH and nutrient and mineral content. Grassland microcosms were established by sowing seeds of 54 species of dry grassland plants into the studied soils. To suppress soil fungi, half of the pots were regularly treated with fungicide. In this way, we studied the independent and combined effects of soil origin and soil community on the establishment of dry grassland communities. The effect of suppressing the soil fungal community on the richness and composition of the plant communities was much stronger than the effect of soil origin. Contrary to our expectations, the effects of these two factors were largely additive, indicating the same degree of importance of soil fungal communities in the establishment of species-rich plant communities in the soils from both origins. The negative effect of suppressing soil fungi on species richness, however, occurred later in the soil from the abandoned field than in the soil from the grassland. This result likely occurred because the negative effects of the suppression of fungi in the field soil were caused mainly by changes in plant community composition and increased competition. In contrast, in the grassland soil, the absence of soil fungi was limiting for plants already at the early stages of their establishment, i.e., in the phases of germination and early recruitment. While fungicide affects not only arbuscular mycorrhizal fungi but also other biota, our data indicate that changes in the AMF communities are the most likely drivers of the observed changes. The effects of other soil biota, however, cannot be fully excluded. These results suggest that the availability of soil fungi may not be the most important limiting factor for the establishment of grassland species in abandoned fields if we manage to reduce the intensity of competition at these sites e.g., by mowing or grazing.

Response of Carbon Fluxes to Soil Moisture Variability across an Alaskan Tundra Landscape

NASA Astrophysics Data System (ADS)

Melton, S.; Natali, S.; Schade, J. D.; Holmes, R. M.; Mann, P. J.; Fiske, G. J.

2017-12-01

Soils in arctic and sub-arctic permafrost regions store large amounts of carbon (C), which is becoming more biologically available as soils warm and permafrost thaws. Microbial decay of organic forms of C can result in the production and emission of carbon dioxide (CO2) and methane (CH4), and the amount and form of C released into the atmosphere depend on organic matter composition and soil conditions. Soil moisture, which is a strong driver of microbial processes, varies spatially and temporally across tundra landscapes and may change dramatically as a result of permafrost thaw. The Yukon-Kuskokwim Delta (YKD) of Alaska is underlain by discontinuous permafrost and is particularly vulnerable to permafrost thaw and soil moisture changes associated with thaw. As permafrost thaws, some areas may dry as drainage increases with increasing thaw depth. Alternatively, permafrost thaw may lead to ground subsidence and saturation of previously dry soils. Our objective was to investigate patterns in C storage and processing across the landscape and in response to changes in soil moisture in the YKD. We analyzed soil C pools (0-30 cm) and CO2 and CH4 concentrations in soils from sites of different land cover and landscape position, including moist and dry peat plateaus, high and low intensity burned plateaus, fens, and drained lakes. We also conducted aerobic and anaerobic soil incubations to determine changes in CO2 and CH4 production under a range of soil moisture conditions. Soils from burned plateaus, which were drier and had lower C content than unburned soils, had higher CO2 production (per g soil) than unburned soils during aerobic incubations. Both increased and decreased moisture reduced CO2 production from soils. Soil drying increased net CH4 uptake in all aerobically-incubated burned soils, and wetting resulted in CH4 emissions from low intensity burn soils. CO2 and CH4 production from fen soils were higher than from the other landscape positions analyzed here. Our results suggest that soil drying could lead to decreased microbial respiration, whereas subsidence may result in increased methanogenesis. Additionally, amplified CH4 release from burned soils after rainfall events or subsidence may accompany the increased fire frequency projected in tundra regions.

Using Artificial Soil and Dry-Column Flash Chromatography to Simulate Organic Substance Leaching Process: A Colorful Environmental Chemistry Experiment

ERIC Educational Resources Information Center

de Avellar, Isa G. J.; Cotta, Tais A. P. G.; Neder, Amarilis de V. Finageiv

2012-01-01

Soil is an important and complex environmental compartment and soil contamination contributes to the pollution of aquifers and other water basins. A simple and low-cost experiment is described in which the mobility of three organic compounds in an artificial soil is examined using dry-column flash chromatography. The compounds were applied on top…

Soil physical and X-ray computed tomographic measurements to investigate small-scale structural differences under strip tillage compared to mulch till and no-till

NASA Astrophysics Data System (ADS)

Pöhlitz, Julia; Rücknagel, Jan; Schlüter, Steffen; Vogel, Hans-Jörg

2017-04-01

In recent years there has been an increasing application of conservation tillage techniques where the soil is no longer turned, but only loosened or left completely untilled. Dead plant material remains on the soil surface, which provides environmental and economic benefits such as the conservation of water, preventing soil erosion and saving time during seedbed preparation. There is a variety of conservation tillage systems, e.g. mulch till, no-till and strip tillage, which is a special feature. In strip tillage, the seed bed is divided into a seed zone (strip-till within the seed row: STWS) and a soil management zone (strip-till between the seed row: STBS). However, each tillage application affects physical soil properties and processes. Here, the combined application of classical soil mechanical and computed tomographic methods is used on a Chernozem (texture 0-30 cm: silt loam) to show small-scale structural differences under strip tillage (STWS, STBS) compared to no-till (NT) and mulch till (MT). In addition to the classical soil physical parameters dry bulk density and saturated conductivity (years: 2012, 2014, 2015) at soil depths 2-8 and 12-18 cm, stress-strain tests were carried out to map mechanical behavior. The stress-strain tests were performed for a load range from 5-550 kPa at 12-18 cm depth (year 2015). Mechanical precompression stress was determined on the stress-dry bulk density curves. Further, CT image cross sections and computed tomographic examinations (average pore size, porosity, connectivity, and anisotropy) were used from the same soil samples. For STBS and NT, a significant increase in dry bulk density was observed over the course of time compared to STWS and MT, which was more pronounced at 2-8 cm than at 12-18 cm depth. Despite higher dry bulk density, STBS displayed higher saturated conductivity in contrast to STWS, which can be attributed to higher earthworm abundance. In strip tillage, structural differences were identified. Mechanical precompression stress was significantly higher for STBS (141 kPa) than STWS (38 kPa). In addition, the CT image cross sections and the computed tomographic parameters confirmed the mechanically more stable soil structure observed under STBS with a higher initial average pore size but lower porosity and connectivity values compared to STWS. The reason for this is the lack of tillage. On the other hand, tillage at STWS created a loosened, porous and connective substrate. For all variants, the increasing load application led to progressive homogenization processes of the soil structure. At the same time, as stress application increased in all variants, the increase in dry bulk density led to a decrease in average pore size, porosity, and connectivity, while anisotropy increased. It was possible to confirm that strip tillage combines the advantages of no-till and a deeper conservation primary tillage, since on the one hand MT and STWS and on the other hand STBS and NT showed very similar soil structures. The computed tomographic parameters therefore provide valuable information about the impact of tillage on microscopic pore space attributes that improve our understanding about soil functional behavior at much larger scales.

Effect of in-situ disturbance within the soil mass on the stress-strain behaviour of silty soil

NASA Astrophysics Data System (ADS)

Noor, Sarah T.; Rabika Rahman, SS; Nahar, Sabiqun

2018-04-01

To date, different techniques have been evolved to collect soil in undisturbed condition so that the in-situ soil behaviour can be determined by carrying out laboratory tests. For the same reason, the execution of undisturbed soil sampling in practice is given a lot of efforts. However, this study brings the fact into consideration that the in-situ soil condition may not remain constant, rather it might vary time to time, because of different internal or external reasons. For example, the internal stress state of soil layers, existing below or above the swelling soil layer, become modified during shrinking and swelling resulting from drying and wetting of swelling clay, respectively. Further, foundations of building may transfer cyclic loads (generated by vibration installed in the building) to the soil below the foundation. Therefore, this study investigates the effects of stress-strain behaviour due to the disturbances on the shear strength of the soil with respect to that of undisturbed specimens. The shear strength of disturbed soil shows deviation from that of undisturbed specimen depending on the different parameters defining the severity of disturbance.

Wet-dry cycles effect on ash water repellency. A laboratory experiment.

NASA Astrophysics Data System (ADS)

Pereira, Paulo; Cerdà, Artemi; Oliva, Marc; Mataix, Jorge; Jordán, Antonio

2014-05-01

In the immediate period after the fire, the ash layer has a strong influence on soil hydrological processes, as runoff, infiltration and erosion. Ash is very dynamic in the space and time. Until the first rainfall periods, ash is (re)distributed by the wind. After it can cover the soil surface, infiltrate or transported to other areas by water transport (Pereira et al., 2013a, b). This will have strong implications on nutrient redistribution and vegetation recovery. Ash layer may affect soil water repellency in different ways, depending on fire severity, soil properties and vegetation. Ash produced at low temperatures after low-severity burning is usually hydrophobic (Bodi et al., 2011, 2012). Wet-dry cycles have implications on ash physical and chemical properties, changing their effects in space and time. The aim of this study is to analyse the effects of fire temperature and severity on ash water repellency. Pinus sylvestris needles were collected in a Lithuania forest in Dzukija National Park (53º 54' N and 24º 22' E), transported to laboratory and washed with deionized water to remove soil particles and other residues. Needle samples were dried during 24 hours and exposed to different temperatures: 200, 300, 400 and 500 ºC, during 2 hours. Ash colour was analysed according to the Munsell Soil Color charts. Ash was black (10 YR 2/1) at 200 ºC, very dark grey (10YR 3/1) at 300 ºC, gray (10YR 5/1) at 400 ºC and light gray (10YR 7/1) at 500 ºC. Ten samples of ash released after each treatment were placed in plastic dishes (50 mm in diameter) in an amount enough to form a 5 mm thick layer, and ash water repellency was measured according to the Water Drop Penetration Test. Later, ash was carefully wetted with 15 ml of deionized water and placed in an oven during 4 days (96 hours), as in Bodí et al. (2012). This procedure was repeated 5 times in order to observe the effects of wet-dry cycles in ash water repellency. The results showed significant differences among wet-dry cycles (Chi Sqr = 184.13 p <0.001) and among temperatures, immediately after treatments (Kruskal-Wallis test: H = 13.64, p<0.01) and after first wet-dry cycle (Kruskal-Wallis test: H =13.85 p<0.01). In the second (Kruskal-Wallis test: =5.80, p >0.05), third (Kruskal-Wallis test: H =3.07, p>0.05), fourth (Kruskal-Wallis test: H=0.75, p>0.05) and fifth (Kruskal-Wallis test: H =0.199, p<0.05) wet-dry cycles, ash water repellency did not show significant differences. After wetting, ash water repellency decreased substantially in the first cycle. These results suggest that wet-dry cycles have important impacts in the reduction of ash water repellency. Nevertheless, this reduction at least in the first cycle is different according to the temperature/severity. Black ash (200 ºC) water repellency was significantly higher than the other temperatures/severities. Further research will be carried out using burned soils and different species. References Bodi, M.B., Doerr, S., Cerda, A., Mataix-Solera, J. (2012) Hydrological effects of a layer of vegetation ash on underlying wettable and water repellent soil. Geoderma, 161, 14-23, 2011. DOI: 10.1016/j.geoderma.2012.01.006. Bodí, M.B., Mataix-Solera, J., Doerr, S.H., Cerdà, A. (2011). The wettability of ash from burned vegetation and its relationship to Mediterranean plant species type, burn severity and total organic carbon content. Geoderma 160, 599-607. DOI:10.1016/j.geoderma.2010.11.009. Pereira, P., Cerdà, A., Úbeda, X., Mataix-Solera, J. Arcenegui, V., Zavala, L. (2013a) Modelling the impacts of wildfire on ash thickness in a short-term period, Land Degradation and Development. DOI: 10.1002/ldr.2195. Pereira, P., Cerdà, A., Úbeda, X., Mataix-Solera, J., Jordan, A. Burguet, M. (2013b) Spatial models for monitoring the spatio-temporal evolution of ashes after fire - a case study of a burnt grassland in Lithuania, Solid Earth, 4, 153-165. DOI: 10.5194/se-4-153-2013.

Nighttime water absorption by a bare loess soil in a coastal desert

NASA Astrophysics Data System (ADS)

Ninari, N.; Berliner, P. R.

2003-04-01

The role of dew in arid and semi-arid ecosystems is considered to be of great importance. It can serve as a water source for the bacteria of biological crust, for plants and for small insects. The Negev Desert is a semiarid region characterized by winter rainfall with a very large inter-annual variability. Reports on measurements carried out in this area mention that up to 180 nights a year with dew were registered by a conventional Hiltner Dew Balance, with intensities that ranged from 0.1 to 0.2 mm per night (yielding a total of 15 mm per year, which is more than 10% of the total rainfall). The Hiltner dew balance is based on the continuous weighing of an artificial condensation plate that has a completely different energy balance from that of the soil surface above which it is installed. The Hiltner dew balance could, therefore, be considered as a ``potential dew" gauge, whose results are probably mainly correlated to atmospheric conditions. The prime objective of this work was, therefore, to quantify the amounts of dew deposition on the soil surface, and to compare these amounts to those measured by the Hiltner balance. Measurements were carried out at the Wadi Mashash Experimental Farm in the Negev. To estimate deposition and evaporation of dew, a micro-lysimeter (diameter: 20 cm; soil depth: 50 cm) with an undisturbed soil sample was installed flush with the soil surface. The following were continuously monitored: micro-lysimeter weight, incoming and reflected short wave radiation, net radiation, dry and wet bulb temperatures, wind speed, and soil heat flux. A Hiltner Dew Balance was placed close by as a reference to compare with previous measurements. Throughout the ``dew period" (spring, summer and fall), and at random intervals, soil samples were taken hourly during the whole night. The uppermost 10 cm of the soil was divided into 1 cm intervals, and the soil moisture content was measured (oven dry). During the above-mentioned night campaigns, no dew deposition could be visually detected on the soil surface. A mass gain was however registered with the ML and an increase in moisture content was observed. The Hiltner balance clearly underestimated dew deposition amounts. These results indicate that although no visual signs of dew deposition could be detected, moisture did penetrate into the soil.

A modern soil carbon stock baseline for the conterminous United States

NASA Astrophysics Data System (ADS)

Loecke, T.; Wills, S. A.; Teachman, G.; Sequeira, C.; West, L.; Wijewardane, N.; Ge, Y.

2016-12-01

The Rapid Carbon Assessment Project was undertaken to ascertain the soil carbon stocks across the conterminous US at one point in time. Sample locations were chosen randomly from the NRI (National Resource Inventory) sampling framework and cover all areas in CONUS with SSURGO certified maps as of Dec 2010. The project was regionalized into 17 areas for logistical reasons. Within each region, soils were grouped by official series description properties. Sites were selected by soil groups and land use/cover as indicated by NRI or NLCD (USGS National Land Cover Dataset) class so that more extensive soils groups and/or land use/covers received more points and less extensive fewer points (with a minimum of 5 sites). Each region had 375 - 400 sites, for a total of approximately 6,400 sites. At each site, basic information about land use, vegetation and management were collected as appropriate and available. Samples were collected from 5 pedons (a central and 4 satellites) per site to a depth of 1m, at 0 - 5cm and by genetic horizon. A volumetric sample was collected for horizons above 50 cm to determine bulk density. For horizons below 50cm (or when a volumetric sample could not be obtained) bulk density was modeled from morphological information. All samples were air dried and crushed to <2mm. The central pedon was analyzed for total and organic carbon at the Kellogg Soil Science Laboratory in Lincoln, NE. A visible near-infrared (VNIR) spectrophotometer was used to predict organic and inorganic carbon contents for all satellites samples. A Hierarchical Bayesian statistical approach was used to estimate C stocks, concentrations, and uncertainty for each sampling level (i.e., CONUS, region, soil group, landuse and site). Carbon concentration and stocks were summarized by surface horizon and depth increments for sites, soil groups, and land use/groups and mapped by linking the values to a raster of SSURGO (Jan 2012) that includes map unit and NLCD classification. This modern soil C stock baseline data set will be useful for many application in climate science and biogeochemistry.

CeO2 nanoparticles induce no changes in phenanthrene toxicity to the soil organisms Porcellionides pruinosus and Folsomia candida.

PubMed

Tourinho, Paula S; Waalewijn-Kool, Pauline L; Zantkuijl, Irene; Jurkschat, Kerstin; Svendsen, Claus; Soares, Amadeu M V M; Loureiro, Susana; van Gestel, Cornelis A M

2015-03-01

Cerium oxide nanoparticles (CeO2 NPs) are used as diesel fuel additives to catalyze oxidation. Phenanthrene is a major component of diesel exhaust particles and one of the most common pollutants in the environment. This study aimed at determining the effect of CeO2 NPs on the toxicity of phenanthrene in Lufa 2.2 standard soil for the isopod Porcellionides pruinosus and the springtail Folsomia candida. Toxicity tests were performed in the presence of CeO2 concentrations of 10, 100 or 1000mg Ce/kg dry soil and compared with results in the absence of CeO2 NPs. CeO2 NPs had no adverse effects on isopod survival and growth or springtail survival and reproduction. For the isopods, LC50s for the effect of phenanthrene ranged from 110 to 143mg/kg dry soil, and EC50s from 17.6 to 31.6mg/kg dry soil. For the springtails, LC50s ranged between 61.5 and 88.3mg/kg dry soil and EC50s from 52.2 to 76.7mg/kg dry soil. From this study it may be concluded that CeO2 NPs have a low toxicity and do not affect toxicity of phenanthrene to isopods and springtails. Copyright © 2014 Elsevier Inc. All rights reserved.

Rhizosphere bacteria containing 1-aminocyclopropane-1-carboxylate deaminase increase yield of plants grown in drying soil via both local and systemic hormone signalling.

PubMed

Belimov, Andrey A; Dodd, Ian C; Hontzeas, Nikos; Theobald, Julian C; Safronova, Vera I; Davies, William J

2009-01-01

Decreased soil water availability can stimulate production of the plant hormone ethylene and inhibit plant growth. Strategies aimed at decreasing stress ethylene evolution might attenuate its negative effects. An environmentally benign (nonchemical) method of modifying crop ethylene relations - soil inoculation with a natural root-associated bacterium Variovorax paradoxus 5C-2 (containing the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase that degrades the ethylene precursor ACC), was assessed with pea (Pisum sativum) plants grown in drying soil. Inoculation with V. paradoxus 5C-2, but not with a transposome mutant with massively decreased ACC deaminase activity, improved growth, yield and water-use efficiency of droughted peas. Systemic effects of V. paradoxus 5C-2 included an amplified soil drying-induced increase of xylem abscisic acid (ABA) concentration, but an attenuated soil drying-induced increase of xylem ACC concentration. A local bacterial effect was increased nodulation by symbiotic nitrogen-fixing bacteria, which prevented a drought-induced decrease in nodulation and seed nitrogen content. Successfully deploying a single bacterial gene in the rhizosphere increased yield and nutritive value of plants grown in drying soil, via both local and systemic hormone signalling. Such bacteria may provide an easily realized, economic means of sustaining crop yields and using irrigation water more efficiently in dryland agriculture.

Moisture and substrate availability constrain soil trace gas fluxes in an eastern Amazonian regrowth forest

NASA Astrophysics Data System (ADS)

Vasconcelos, Steel S.; Zarin, Daniel J.; Capanu, Marinela; Littell, Ramon; Davidson, Eric A.; Ishida, Francoise Y.; Santos, Elisana B.; Araújo, Maristela M.; AragãO, DéBora V.; Rangel-Vasconcelos, LíVia G. T.; de Assis Oliveira, Francisco; McDowell, William H.; de Carvalho, Claudio José R.

2004-06-01

Changes in land-use and climate are likely to alter moisture and substrate availability in tropical forest soils, but quantitative assessment of the role of resource constraints as regulators of soil trace gas fluxes is rather limited. The primary objective of this study was to quantify the effects of moisture and substrate availability on soil trace gas fluxes in an Amazonian regrowth forest. We measured the efflux of carbon dioxide (CO2), nitric oxide (NO), nitrous oxide (N2O), and methane (CH4) from soil in response to two experimental manipulations. In the first, we increased soil moisture availability during the dry season by irrigation; in the second, we decreased substrate availability by continuous removal of aboveground litter. In the absence of irrigation, soil CO2 efflux decreased during the dry season while irrigation maintained soil CO2 efflux levels similar to the wet season. Large variations in soil CO2 efflux consistent with a significant moisture constraint on respiration were observed in response to soil wet-up and dry-down events. Annual soil C efflux for irrigated plots was 27 and 13% higher than for control plots in 2001 and 2002, respectively. Litter removal significantly reduced soil CO2 efflux; annual soil C efflux in 2002 was 28% lower for litter removal plots compared to control plots. The annual soil C efflux:litterfall C ratio for the control treatment (4.0-5.2) was consistent with previously reported values for regrowth forests that indicate a relatively large belowground C allocation. In general, fluxes of N2O and CH4 were higher during the wet season and both fluxes increased during dry-season irrigation. There was no seasonal effect on NO fluxes. Litter removal had no significant impact on N oxide or CH4 emissions. Net soil nitrification did not respond to dry-season irrigation, but was somewhat reduced by litter removal. Overall, these results demonstrate significant soil moisture and substrate constraints on soil trace gas emissions, particularly for CO2, and suggest that climate and land-use changes that alter moisture and substrate availability are therefore likely to have an impact on atmosphere chemistry.

Soil contamination with olive mill wastes negatively affects microbial communities, invertebrates and plants.

PubMed

Hentati, Olfa; Oliveira, Vanessa; Sena, Clara; Bouji, Mohamed Seddik Mahmoud; Wali, Ahmed; Ksibi, Mohamed

2016-10-01

The aim of the present study was to evaluate the ecotoxicological effects of olive mill waste (OMW) on soil habitat function. To this end, soil samples from OMW evaporating ponds (S1-S5) located at Agareb (Sfax, Tunisia) and a reference soil (R) were collected. The effects of OMW on the springtails Folsomia candida (F.c.), the earthworm species Eisenia fetida (E.f.), Enchytraeus crypticus (E.c.) reproduction and on the soil living microbial communities were investigated. E.f. reproduction and tomato growth assays were performed in the reference soil amended with 0.43 to 7.60 % (w OMW /w ref-soil ) mass ratios of dried OMW. Changes in microbial function diversity were explored using sole-carbon-source utilization profiles (BiologEcoPlates ® ). E.f. absolutely avoided (100 %) the most polluted soil (S4) while the F.c. moderately avoided (37.5 ± 7.5 %) the same soil. E.c. reproduction in S4 was significantly lower than in S1, S2, S3 and S5, and was the highest in R soil. Estimated effect concentration EC 50 for juveniles' production by E.f., and for tomato fresh weight and chlorophyll content were 0.138, 0.6 and 1.13 %, respectively. Community level physiological profiles (CLPPs) were remarkably different in R and S4 and a higher similarity was observed between soils S1, S2, S3 and S5. Principal component analysis (PCA) revealed that differences between soil microbial functional diversity were mainly due to high polyphenol concentrations, while the salinity negatively affected E.c. reproduction in OMW contaminated soils. These results clearly reflect the high toxicity of dried OMW when added to agricultural soils, causing severe threats to terrestrial ecosystem functions and services provided by invertebrates and microbial communities.

The Ups and Downs of Rhizosphere Resource Exchange

NASA Astrophysics Data System (ADS)

Cardon, Z. G.; Fu, C.; Wang, G.; Stark, J.

2014-12-01

Hydraulic redistribution (HR) of soil water by plants occurs in seasonally dry ecosystems worldwide. During HR, soil water flows from wet soil into roots, through the root system, and out of roots into dry rhizosphere soil. Hydraulic redistribution affects plant physiology and landscape hydrology, and it has long been hypothesized that upward HR of deep water to dry, nutrient-rich surface soil may also stimulate soil nutrient cycling and thus enhance nutrient availability to plants in the field. We report results from a sagebrush-steppe field experiment in northern Utah, USA, showing that stimulation of sagebrush-mediated HL increased rates of nitrogen cycling in the surface soil layer around shrubs at summer's end, and more than quadrupled uptake of nitrogen into developing sagebrush inflorescences. We have built on these empirical data by folding Ryel et al.'s (2002) HR formulation into CLM4.5 and examining how well the combined model can simultaneously simulate measured evapotranspiration, the vertical profile of soil moisture, and the amplitude of HR-associated diel changes in water content, at multiple seasonally-dry Ameriflux sites: Wind River Crane (US-Wrc), Southern California Climate Gradient (US-SCs,g,f,w,d,&c), and Santa Rita Mesquite Savanna (US-SRM). The simulated hydraulic lift during the dry periods has an average value in the range from 0.09 (at US-SCc) to 0.64 (at US-SCf) mm H2O d-1. In many cases, the combined model reproduced seasonal and daily (diel) observations with reasonable accuracy. Among the many model parameters tested, the Clapp and Hornberger parameter "B" in CLM4.5 was critical for a realistic simulation of soil moisture. Modeled HR was also sensitive to the maximum radial soil-root conductance and the soil water potential where that conductance is reduced by 50%. Our next step is to explore how modeled carbon and nutrient cycling in soil layers are affected by redistributed water in the soil column caused by inclusion of HR in CLM4.5.

Permeability changes induced by microfissure closure and opening in tectonized materials. Effect on slope pore pressure regime.

NASA Astrophysics Data System (ADS)

De la Fuente, Maria; Vaunat, Jean; Pedone, Giuseppe; Cotecchia, Federica; Sollecito, Francesca; Casini, Francesca

2015-04-01

Tectonized clays are complex materials characterized by several levels of structures that may evolve during load and wetting/drying processes. Some microstructural patterns, as microfissures, have a particular influence on the value of permeability which is one of the main factors controlling pore pressure regime in slopes. In this work, the pore pressure regime measured in a real slope of tectonized clay in Southern Italy is analyzed by a numerical model that considers changes in permeability induced by microfissure closure and opening during the wetting and drying processes resulting from climatic actions. Permeability model accounts for the changes in Pore Size Distribution observed by Microscopy Intrusion Porosimetry. MIP tests are performed on representative samples of ground in initial conditions ("in situ" conditions) and final conditions (deformed sample after applying a wetting path that aims to reproduce the saturation of the soil under heavy rains). The resulting measurements allow for the characterization at microstructural level of the soil, identifying the distribution of dominant families pores in the sample and its evolution under external actions. Moreover, comparison of pore size density functions allows defining a microstructural parameter that depends on void ratio and degree of saturation and controls the variation of permeability. Model has been implemented in a thermo-hydro-mechanical code provided with a special boundary condition for climatic actions. Tool is used to analyze pore pressure measurements obtained in the tectonized clay slope. Results are analyzed at the light of the effect that permeability changes during wetting and drying have on the pore pressure regime.

Autoclaving as a mean of modifying the soil wettability characteristics

NASA Astrophysics Data System (ADS)

Urbanek, Emilia; Bodi, Merche; Shakesby, Rick; Doerr, Stefan

2010-05-01

Studies of soil water repellency have often attempted to isolate its hydrological impact by comparing responses of wettable and water repellent soils. It is, however, almost impossible to identify natural wettable and water repellent soils that are otherwise fully comparable. Furthermore no established methodology exists that allows changing a soil from wettable to water repellent (or vice versa) without affecting its chemical composition. Approaches used for rendering wettable soil (or sands) water repellent involve coating particles with hydrophobic or commercial water repellent spray. Heating soil to temperatures >300 °C has been used to eliminate existing water repellency from samples, but this can permanently alter the composition of organic matter. Here we report on a new technique for rendering wettable soil water repellent involving autoclaving. Autoclaving is commonly applied in medicine and biology for sterilization. It uses moist heat and pressure to destroy the bacteria, viruses and fungi. The same method has also been used in soil ecology studies for selective removal of certain micro-organisms. In our study, soils at various moisture contents were autoclaved in sealed bags for 1hr at 121°C. The soils became water repellent and the degree of water repellency was found to be dependent on the original soil moisture content and the soil wettability remained unchanged even with further drying of the soil up to 105°C. No changes in soil wettability were found after autoclaving very dry or wet soils. Only at certain intermediate water contents was the soil able to switch to a hydrophobic state. We suspect that the changes occurring during the autoclaving involve molecular orientation of hydrophobic and hydrophilic groups of soil organic matter, and moist heat and pressure cause the hydrophobic groups to be directed towards the outside of the soil particles which consequently repels water. Treatment of soil in this way presents a simple, inexpensive method of making a soil hydrophobic without changing its chemical composition. This has considerable potential for controlled experiments requiring both soils that differ only in terms of their degree of hydrophobicity.

The Cause of the Hot Spot in Vegetation Canopies and Soils: Shadow-Hiding Versus Coherent Backscatter

NASA Technical Reports Server (NTRS)

Hapke, Bruce; DiMucci, Dominick; Nelson, Robert; Smythe, William

1996-01-01

Two different mechanisms, shadow-hiding and coherent backscatter, can cause a hot spot, or opposition effect, in the bidirectional reflectance of vegetation and soils. Because the two mechanisms sample different properties, it is important to know which one is primarily responsible in a given medium. This question can be answered by measuring the bidirectional reflectance in circularly polarized light. If the results of the limited experiments reported here can be extrapolated to a wider range of materials, it appears that the primary cause of the hot spot in most vegetation canopies and in moist, clumpy soils is shadow-hiding. However, in vegetation with large numbers of wavelength-sized structures, such as mosses, and in dry, fine-grained soils, the hot spot is dominated by coherent backscatter.

Intermittent spring flooding of agricultural fields will increase net global-warming potential of greenhouse gas fluxes

NASA Astrophysics Data System (ADS)

Paul, R. F.; Smyth, E. M.; Smith, C. M.; Kantola, I. B.; Krichels, A.; Yang, W. H.; DeLucia, E. H.

2014-12-01

The U.S. Corn Belt is currently a net source of carbon dioxide and nitrous dioxide to the atmosphere but is also a weak sink for methane. Climate change is projected to increase the frequency and duration of spring precipitation in the North American Midwest, resulting in intermittent flooding and ponding in agricultural fields. Inundation changes the greenhouse gas (GHG) fluxes of the soil, especially by promoting methanogenesis under anoxic conditions. DNA and 16S cDNA sequencing results of earlier, similar experiments confirmed the presence of methanogens in soil samples, albeit in low abundance (representing <0.01% of reads per sample). We installed collars into bare ground of a central Illinois research field to experiment with flooding conditions and observe changes in gas fluxes, microbial community, and soil chemistry. We established three treatments of five replicates—control, continuously flooded, and intermittently flooded—each with separate collars for gas flux measurements, soil sample collection, and soil probe measurements. A drip irrigation system flooded the headspaces of the collars to produce flooding events. The continuously flooded collars were maintained in a flooded condition for the duration of the experiment, and the intermittently flooded collars were flooded for 72 hours per flooding event and then kept dry for at least 5 days before the next flooding event. We measured net concentrations of N2O, CH4, and CO2 in situ using a static chamber connected to a cavity ringdown spectrometer. We found that the periodicity of wetting and drying events induces hysteresis effects that push GHG shifts to occur rapidly (< 1 hr). Integrating fluxes across the period of the experiment, the intermittently flooded collars showed 88.7% higher global-warming potential of GHG fluxes at the 100-year horizon versus control, with most of change driven by increased net CO2 flux (87.1% higher) and net methane flux (29 times higher). These data indicate that more frequent flooding and ponding events will have a significant impact of increasing the soil GHG emissions from the U.S. Corn Belt region.

Germination and Seed Bank Studies of Macbridea alba (Lamiaceae), a Federally Theatened Plant

Treesearch

Dana Madsen Schulze; John L. Walker; Timothy P. Spira

2002-01-01

Macbridea alba (Lamiaceae) is a Federally threatened plant endemic to Florida. Seedlings are rarely observed in natural populations, but seed production has been documented. We assessed the germinability of dry-stored seeds and of experimentally buried seeds, and sampled soil to detect a persistent seed bank.More than 20% of recorded seeds...

Field soil aggregate stability kit for soil quality and rangeland health evaluations

USGS Publications Warehouse

Herrick, J.E.; Whitford, W.G.; de Soyza, A. G.; Van Zee, J. W.; Havstad, K.M.; Seybold, C.A.; Walton, M.

2001-01-01

Soil aggregate stability is widely recognized as a key indicator of soil quality and rangeland health. However, few standard methods exist for quantifying soil stability in the field. A stability kit is described which can be inexpensively and easily assembled with minimal tools. It permits up to 18 samples to be evaluated in less than 10 min and eliminates the need for transportation, minimizing damage to soil structure. The kit consists of two 21??10.5??3.5 cm plastic boxes divided into eighteen 3.5??3.5 cm sections, eighteen 2.5-cm diameter sieves with 1.5-mm distance openings and a small spatula used for soil sampling. Soil samples are rated on a scale from one to six based on a combination of ocular observations of slaking during the first 5 min following immersion in distilled water, and the percent remaining on a 1.5-mm sieve after five dipping cycles at the end of the 5-min period. A laboratory comparison yielded a correlation between the stability class and percent aggregate stability based on oven dry weight remaining after treatment using a mechanical sieve. We have applied the method in a wide variety of agricultural and natural ecosystems throughout western North America, including northern Mexico, and have found that it is highly sensitive to differences in management and plant community composition. Although the field kit cannot replace the careful laboratory-based measurements of soil aggregate stability, it can clearly provide valuable information when these more intensive procedures are not possible.

[Estacionalidad de parásitos intestinales en suelos periurbanos de la ciudad de Neuquén, Patagonia, Argentina].

PubMed

Pierangeli, Nora Beatriz; Giayetto, Alejandro Lorenzo; Manacorda, Ana Maria; Barbieri, Liliana Marta; Soriano, Silvia Viviana; Veronesi, Alicia; Pezzani, Betina Cecilia; Minvielle, Marta Cecilia; Basualdo, Juan Angel

2003-03-01

To determine the presence of eggs, larva, cysts and oocysts of intestinal parasites in the soil of a suburb of Neuquén city during 1 year in order to evaluate their seasonal fluctuations in relation to climatic data and soil characteristics in the studied area. A total of 107 soil samples were processed for parasite isolation by sedimentation and flotation methods during the four seasons of the year. Meteorological data were registered and physical, chemical and structural characteristics of the soil were analysed. About 28.9% of the soil samples were positive for at least one parasite form. Six protozoa species (cysts of Entamoeba sp., Enteromonas sp., Endolimax sp., Giardia sp., Iodamoeba sp. and coccidia oocysts) were recovered, but neither larvae nor eggs of human or animal helminths parasites were detected. The percentage of contaminated soil samples and the diversity of species showed a marked decrease in the warm and dry months of the summer. The soil was sandy, without vegetable cover, well drained, and with scarce organic matter content. The frequencies of parasite recovery and the number of species show seasonal fluctuations related to the rainfall. The importance of soil as a risk factor for the transmission of intestinal parasites in the studied area is conditioned by its structural characteristics, which prevent retaining the humidity, and by climatic variables. The interrelation of both factors determines unfavourable conditions that could explain the low level of contamination observed in soil as well as the absence of eggs and helminth larvae.

Using 13C labeled glucose to determine soil microbial and physical controls of new C incorporation under drying-rewetting cycles and conservation agricultural management

NASA Astrophysics Data System (ADS)

Li, L.; Schaeffer, S. M.

2017-12-01

Drying-rewetting cycles can induce carbon (C) depletion in soil, while conservation agricultural management aims at soil C sequestration. Understanding the combined effect of drying-rewetting cycles and conservation management is critical for sustaining agricultural soil under climate change. Soil organic C can be stored in a relatively rapidly cycling active pool, or a more slowly cycling passive pool. We conducted a 24-days mesocosm incubation using an agricultural soil from western Tennessee under 35-years of conservation management. Different lengths of drought period before rewetting of 0, 3, 6, and 24 days were applied on the mesocosms. To trace the fate of newly added C, 13C labeled glucose was added to the mesocosms at the beginning of the incubation. After 24 days, dissolvable organic C, microbial biomass C, accumulative microbial respiration, and extracellular enzyme activity were analyzed to evaluate the active C pool; hydrogen peroxide oxidation and aggregate size fractionation were used to examine the passive C pool. The highest cumulative microbial respiration was found in the 6-days treatment combining a N-fixing cover crop with no-tillage, and the lowest in the 24-day treatment with a wheat cover crop combined with conventional-tillage (1000.0±20.5 and 106.8±17.5 µg C-CO2 g-1 dry soil, respectively). The 6-days treatment induced 0.5-4.3 times higher cumulative C-CO2 emission than the 3-days treatment. The proportion of macroaggregates in bulk soil varied between 97.2% and 76.7%, and it was negatively correlated with drying-rewetting frequency. The proportion of microaggregates in bulk soil varied between 21.9% and 2.1%, and it was positively correlated with drying-rewetting frequency. 13C recovery rate in bulk soil varied between 11-53%. The vetch-cover-crop-with-no-tillage treatment facilitated 13C accumulation the most. Our results show that the N fixing cover crops combined with no-tillage treatment induced the highest C accumulation in bulk soil, while the no cover crop combined with conventional tillage induced the lowest C concentration. Our results show that frequent drying-rewetting cycles disrupt macroaggregates and release the microaggregates within macroaggregates, and favor greater C loss combined with greater C storage in less stable aggregate fractions.

Inter-laboratory variation in the chemical analysis of acidic forest soil reference samples from eastern North America

USGS Publications Warehouse

Ross, Donald S.; Bailiey, Scott W; Briggs, Russell D; Curry, Johanna; Fernandez, Ivan J.; Fredriksen, Guinevere; Goodale, Christine L.; Hazlett, Paul W.; Heine, Paul R; Johnson, Chris E.; Larson, John T; Lawrence, Gregory B.; Kolka, Randy K; Ouimet, Rock; Pare, D; Richter, Daniel D.; Shirmer, Charles D; Warby, Richard A.F.

2015-01-01

Long-term forest soil monitoring and research often requires a comparison of laboratory data generated at different times and in different laboratories. Quantifying the uncertainty associated with these analyses is necessary to assess temporal changes in soil properties. Forest soil chemical properties, and methods to measure these properties, often differ from agronomic and horticultural soils. Soil proficiency programs do not generally include forest soil samples that are highly acidic, high in extractable Al, low in extractable Ca and often high in carbon. To determine the uncertainty associated with specific analytical methods for forest soils, we collected and distributed samples from two soil horizons (Oa and Bs) to 15 laboratories in the eastern United States and Canada. Soil properties measured included total organic carbon and nitrogen, pH and exchangeable cations. Overall, results were consistent despite some differences in methodology. We calculated the median absolute deviation (MAD) for each measurement and considered the acceptable range to be the median 6 2.5 3 MAD. Variability among laboratories was usually as low as the typical variability within a laboratory. A few areas of concern include a lack of consistency in the measurement and expression of results on a dry weight basis, relatively high variability in the C/N ratio in the Bs horizon, challenges associated with determining exchangeable cations at concentrations near the lower reporting range of some laboratories and the operationally defined nature of aluminum extractability. Recommendations include a continuation of reference forest soil exchange programs to quantify the uncertainty associated with these analyses in conjunction with ongoing efforts to review and standardize laboratory methods.

In situ detection of tree root distribution and biomass by multi-electrode resistivity imaging.

PubMed

Amato, Mariana; Basso, Bruno; Celano, Giuseppe; Bitella, Giovanni; Morelli, Gianfranco; Rossi, Roberta

2008-10-01

Traditional methods for studying tree roots are destructive and labor intensive, but available nondestructive techniques are applicable only to small scale studies or are strongly limited by soil conditions and root size. Soil electrical resistivity measured by geoelectrical methods has the potential to detect belowground plant structures, but quantitative relationships of these measurements with root traits have not been assessed. We tested the ability of two-dimensional (2-D) DC resistivity tomography to detect the spatial variability of roots and to quantify their biomass in a tree stand. A high-resolution resistivity tomogram was generated along a 11.75 m transect under an Alnus glutinosa (L.) Gaertn. stand based on an alpha-Wenner configuration with 48 electrodes spaced 0.25 m apart. Data were processed by a 2-D finite-element inversion algorithm, and corrected for soil temperature. Data acquisition, inversion and imaging were completed in the field within 60 min. Root dry mass per unit soil volume (root mass density, RMD) was measured destructively on soil samples collected to a depth of 1.05 m. Soil sand, silt, clay and organic matter contents, electrical conductivity, water content and pH were measured on a subset of samples. The spatial pattern of soil resistivity closely matched the spatial distribution of RMD. Multiple linear regression showed that only RMD and soil water content were related to soil resistivity along the transect. Regression analysis of RMD against soil resistivity revealed a highly significant logistic relationship (n = 97), which was confirmed on a separate dataset (n = 67), showing that soil resistivity was quantitatively related to belowground tree root biomass. This relationship provides a basis for developing quick nondestructive methods for detecting root distribution and quantifying root biomass, as well as for optimizing sampling strategies for studying root-driven phenomena.

Determination of the Thermal Properties of Sands as Affected by Water Content, Drainage/Wetting, and Porosity Conditions for Sands With Different Grain Sizes

NASA Astrophysics Data System (ADS)

Smits, K. M.; Sakaki, T.; Limsuwat, A.; Illangasekare, T. H.

2009-05-01

It is widely recognized that liquid water, water vapor and temperature movement in the subsurface near the land/atmosphere interface are strongly coupled, influencing many agricultural, biological and engineering applications such as irrigation practices, the assessment of contaminant transport and the detection of buried landmines. In these systems, a clear understanding of how variations in water content, soil drainage/wetting history, porosity conditions and grain size affect the soil's thermal behavior is needed, however, the consideration of all factors is rare as very few experimental data showing the effects of these variations are available. In this study, the effect of soil moisture, drainage/wetting history, and porosity on the thermal conductivity of sandy soils with different grain sizes was investigated. For this experimental investigation, several recent sensor based technologies were compiled into a Tempe cell modified to have a network of sampling ports, continuously monitoring water saturation, capillary pressure, temperature, and soil thermal properties. The water table was established at mid elevation of the cell and then lowered slowly. The initially saturated soil sample was subjected to slow drainage, wetting, and secondary drainage cycles. After liquid water drainage ceased, evaporation was induced at the surface to remove soil moisture from the sample to obtain thermal conductivity data below the residual saturation. For the test soils studied, thermal conductivity increased with increasing moisture content, soil density and grain size while thermal conductivity values were similar for soil drying/wetting behavior. Thermal properties measured in this study were then compared with independent estimates made using empirical models from literature. These soils will be used in a proposed set of experiments in intermediate scale test tanks to obtain data to validate methods and modeling tools used for landmine detection.

Occurrence of nonylphenol and nonylphenol monoethoxylate in soil and vegetables from vegetable farms in the Pearl River Delta, South China.

PubMed

Cai, Quan-Ying; Huang, Hui-Juan; Lü, Huixiong; Mo, Ce-Hui; Zhang, Jun; Zeng, Qiao-Yun; Tian, Jun-Jian; Li, Yan-Wen; Wu, Xiao-Lian

2012-07-01

Low molecular-mass nonylphenol ethoxylates (NPEOs) and 4-nonylphenol (NP) are biodegradation products of higher molecular mass NPEOs used as surface active agents, and they are endocrine-disrupting contaminants. In this study, surface soil (0-20 cm) samples and different vegetable samples were collected from 27 representative vegetable farms located in Shenzhen, Dongguan, and Huizhou within the Pearl River Delta region, South China, and NP and nonylphenol monoethoxylate (NP(1)EO) were analyzed using high-performance liquid chromatography with ultraviolet detection. The results show that NP and NP(1)EO were detected in soil and vegetable samples. The concentrations of NP and NP(1)EO in soil samples ranged from nondetectable (ND) to 7.22 μg kg(-1) dry weight (dw) and from ND to 8.24 μg kg(-1) dw, respectively. The average concentrations of both NP and NP(1)EO in soil samples decreased in the following order: Dongguan > Huizhou > Shenzhen. The levels of NP and NP(1)EO in vegetable samples varied from 1.11 to 4.73 μg kg(-1) dw and from 1.32 to 5.33 μg kg(-1) dw, respectively. The greatest levels of both NP and NP(1)EO were observed in water spinach, and the lowest levels of NP and NP(1)EO were recorded in cowpea. The bioconcentration factors (the ratio of contaminant concentration in plant tissue to soil concentration) of NP and NP(1)EO were <1.0 (mean 0.535 and 0.550, respectively). The occurrences of NP and NP(1)EO in this study are compared with other studies, and their potential sources are discussed.

Geochemical Transformation of Cadmium (Cd) from Creek to Paddy Fields in W Thailand

NASA Astrophysics Data System (ADS)

Kosolsaksakul, Peerapat; Graham, Margaret; Farmer, John

2013-04-01

Extensive Cd contamination of paddy soils in Tak Province, western Thailand, a consequence of Zn mining activities, was first established in 2005 and medical studies showed that the health of local communities was being impaired. Mae Tao, Tak Province, comprising many paddy fields and irrigation canals, has been selected for this study of the geochemical transformation of Cd from the contamination source in the mountainous region to the east of the study site through the community irrigation system to the paddy soils. The aim of this research is to (i) investigate the geochemical transformation of Cd as it is transported from the main irrigation creek through the canals and to the paddy fields, (ii) assess the availability of Cd to rice plants, which may be affected by both chemical and physical factors, and (iii) trial some practical treatments to minimise Cd concentrations in rice grains. Soils, irrigation canal sediments and water samples were collected during the dry season and at the onset of the rainy season. Rice samples were collected at harvesting time and samples of soil fertiliser were also obtained. Water samples were filtered, ultrafiltered and analysed by ICP-MS whilst sub-samples of dried, ground soils and sediments were first subjected to micro-wave assisted acid digestion (modified US EPA method 3052). XRD and SEM-EDX methods were used for mineralogical characterisation and selective chemical extractions have assisted in the characterisation of solid phase Cd associations. Soil Cd concentrations were in the range 2.5-87.6 µg g-1, with higher values being obtained for fields furthest from the main creek. Although current irrigation water Cd inputs are low (mean 1.9 μg L-1; flood period), high loads of suspended particles still contribute additional Cd (4.2-9.8 µg L-1) to the paddy fields. For bioavailability assessment by a 3-step BCR sequential extraction, 70-90% Cd was in the exchangeable; HOAc-extractable fraction. That indicated that most of the Cd was in water soluble, exchangeable and carbonate-bound forms. For the fields with highest Cd concentration, SEM-EDX analysis identified two forms of Cd, i.e. Cd-Clay and Cd-CaCO3, in good agreement with the sequential extraction data. The predominance of easily extractable forms in the paddy field soils suggests that Cd may be readily absorbed by the rice plants. After harvesting, the Cd concentration in rice grains ranged from 0.05-4.0 µg g-1 and the concentration trends across the group of 18 fields matched well with the soil Cd data. Rice from nine out of the 18 fields contained Cd at greater than the safe level of 0.4 µg g-1.

Influence of dry soil on the ability of Formosan Subterranean Termites, Coptotermes formosanus, to locate food sources.

USDA-ARS?s Scientific Manuscript database

The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki, to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three-chambered apparatus were compared for treatments where the soil in the center contai...

Influence of Dry Soil on the Ability of Formosan Subterranean Termites (Coptotermes formosanus) to Locate Food Sources

USDA-ARS?s Scientific Manuscript database

The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki, to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three-chambered apparatus were compared for treatments where the soil in the center contai...

Timing of seed dispersal generates a bimodal seed bank depth distribution

USGS Publications Warehouse

Espinar, J.L.; Thompson, K.; Garcia, L.V.

2005-01-01

The density of soil seed banks is normally highest at the soil surface and declines monotonically with depth. Sometimes, for a variety of reasons, peak density occurs below the surface but, except in severely disturbed soils, it is generally true that deeper seeds are older. In seasonally dry habitats that develop deep soil cracks during the dry season, it is possible that some seeds fall down cracks and rapidly become deeply buried. We investigated this possibility for three dominant clonal perennials (Scirpus maritimus, S. litoralis, and Juncus subulatus) in the Don??ana salt marsh, a nontidal marsh with a Mediterranean climate located in southwest Spain. Two species, which shed most of their seed during the dry season and have seeds with low buoyancy, had bimodal viable seed depth distributions, with peak densities at the surface and at 16-20 cm. A third species, which shed most seeds after soil cracks had closed and had seeds with high buoyancy, had viable seeds only in surface soil. Bimodal seed bank depth distributions may be relatively common in seasonally dry habitats with fine-textured soils, but their ecological significance has not been investigated.

Individual contributions of climate and vegetation change to soil moisture trends across multiple spatial scales.

PubMed

Feng, Huihui

2016-09-07

Climate and vegetation change are two dominating factors for soil moisture trend. However, their individual contributions remain unknown due to their complex interaction. Here, I separated their contributions through a trajectory-based method across the global, regional and local scales. Our results demonstrated that climate change accounted for 98.78% and 114.64% of the global drying and wetting trend. Vegetation change exhibited a relatively weak influence (contributing 1.22% and -14.64% of the global drying and wetting) because it occurred in a limited area on land. Regionally, the impact of vegetation change cannot be neglected, which contributed -40.21% of the soil moisture change in the wetting zone. Locally, the contributions strongly correlated to the local environmental characteristics. Vegetation negatively affected soil moisture trends in the dry and sparsely vegetated regions and positively in the wet and densely vegetated regions. I conclude that individual contributions of climate and vegetation change vary at the global, regional and local scales. Climate change dominates the soil moisture trends, while vegetation change acts as a regulator to drying or wetting the soil under the changing climate.

Mitigation of Prion Infectivity and Conversion Capacity by a Simulated Natural Process—Repeated Cycles of Drying and Wetting

PubMed Central

Yuan, Qi; Eckland, Thomas; Telling, Glenn; Bartz, Jason; Bartelt-Hunt, Shannon

2015-01-01

Prions enter the environment from infected hosts, bind to a wide range of soil and soil minerals, and remain highly infectious. Environmental sources of prions almost certainly contribute to the transmission of chronic wasting disease in cervids and scrapie in sheep and goats. While much is known about the introduction of prions into the environment and their interaction with soil, relatively little is known about prion degradation and inactivation by natural environmental processes. In this study, we examined the effect of repeated cycles of drying and wetting on prion fitness and determined that 10 cycles of repeated drying and wetting could reduce PrPSc abundance, PMCA amplification efficiency and extend the incubation period of disease. Importantly, prions bound to soil were more susceptible to inactivation by repeated cycles of drying and wetting compared to unbound prions, a result which may be due to conformational changes in soil-bound PrPSc or consolidation of the bonding between PrPSc and soil. This novel finding demonstrates that naturally-occurring environmental process can degrade prions. PMID:25665187

Methane emissions and uptake in temperate and tropical forest trees on free-draining soils.

NASA Astrophysics Data System (ADS)

Welch, Bertie; Sayer, Emma; Siegenthaler, Andy; Gauci, Vincent

2016-04-01

Forests play an important role in the exchange of radiatively important gases with the atmosphere. Previous studies have shown that in both temperate and tropical wetland forests tree stems are significant sources of methane (CH4), yet little is known about trace greenhouse gas dynamics in free-draining soils that dominate global forested areas. We examined trace gas (CH4 and N2O) fluxes from both soils and tree stems in a lowland tropical forest on free-draining soils in Panama, Central America and from a deciduous woodland in the United Kingdom. The tropical field site was a long-term experimental litter manipulation experiment in the Barro Colorado Nature Monument within the Panama Canal Zone, fluxes were sampled over the dry to wet season transition (March-August) in 2014 and November 2015. Temperate fluxes were sampled at Wytham Woods, Oxfordshire, over 12 months from February 2015 to January 2016. Tree stem samples were collected via syringe from temporary chambers strapped to the trees (as per Siegenthaler et al. (2015)) and the soil fluxes were sampled from permanently installed collars inserted to a 3cm depth. We found that seasonality (precipitation) is a significant driver of changing soil exchange from methane uptake to emission at the Panama sites. Experimental changes to litter quantity only become significant when coupled with seasonal change. Seasonal variability is an important control of the fluxes at out temperate forest site with changes in temperature and soil water content leading to changes in soil and tree stem trace gas fluxes from Wytham Woods. Siegenthaler, A., Welch, B., Pangala, S. R., Peacock, M., and Gauci, V.: Technical Note: Semi-rigid chambers for methane gas flux measurements on tree-stems, Biogeosciences Discuss., 12, 16019-16048, doi:10.5194/bgd-12-16019-2015, 2015.

Effect of soil water content on spatial distribution of root exudates and mucilage in the rhizosphere

NASA Astrophysics Data System (ADS)

Holz, Maire; Zarebanadkouki, Mohsen; Kuzyakov, Yakov; Carminati, Andrea

2016-04-01

Water and nutrients are expected to become the major factors limiting food production. Plant roots employ various mechanisms to increase the access to these limited soil resources. Low molecular root exudates released into the rhizosphere increase nutrient availability, while mucilage improves water availability under low moisture conditions. However, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was therefore to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging at different levels of water stress. Maize plants were grown in rhizotrons filled with a silty soil and were exposed to varying soil conditions, from optimal to dry. Mucilage distribution around the roots was estimated from the profiles of water content in the rhizosphere - note that mucilage increases the soil water content. The profiles of water content around different root types and root ages were measured with neutron radiography. Rhizosphere extension was approx. 0.7 mm and did not differ between wet and dry treatments. However, water content (i.e. mucilage concentration) in the rhizosphere of plants grown in dry soils was higher than for plants grown under optimal conditions. This effect was particularly pronounced near the tips of lateral roots. The higher water contents near the root are explained as the water retained by mucilage. 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) was used to estimate the distribution of all rhizodeposits. Two days after labelling, 14C distribution was measured using phosphor-imaging. To quantify 14C in the rhizosphere a calibration was carried out by adding given amounts of 14C-glucose to soil. Plants grown in wet soil transported a higher percentage of 14C to the roots (14Croot/14Cshoot), compared to plants grown under dry conditions (46 vs. 36 %). However, the percentage of 14C allocated from roots to rhizosphere (14Crhizosphere/14Croot) was double in plants grown under dry conditions (0.43 vs. 0.75 %). Plants grown in wet soils showed a faster root growth (1.4 cm d-1) compared to plants in dry soil (1 cm d-1). Compared to the results with neutron radiography, rhizosphere extension of 14C was generally higher and strongly depended on root type: it was 2 mm for main roots and 1 mm for lateral roots. This indicates that low molecular exudates diffuse further into the soil than mucilage. As for mucilage, concentration of 14C was higher in the rhizosphere of plants grown under dry conditions. This observation can be explained by: (a) higher allocation of 14C from roots to rhizosphere in dry soils, (b) a fast diffusion of exudates in wet soils, and (c) faster root growth in wet soils, which results in lower exudation per root length. In summary, the combination of neutron radiography and 14C imaging was successfully used to visualize and to quantify the distribution of mucilage and root exudates in the rhizosphere of plants grown in soil. The high concentration of root exudates in rhizosphere under dry conditions might be strategy of plants to increase their water and nutrient availability unfavorable conditions.

Effect of organic matter and roots in soil respiration in a Mediterranean riparian areas in Central Spain

NASA Astrophysics Data System (ADS)

Gonzalez-Garrido, Laura; Delgado, Juan Antonio; Martinez, Teodora

2010-05-01

Soil respiration is one of the largest carbon flux components within terrestrial ecosystems, and small changes in the magnitude of soil respiration could have a large effect on the concentration of CO2 in the atmosphere. The main objective is evaluating the factors controlling soil respiration on the global carbon cycle in riparian areas of Henares River. We evaluated total soil respiration as it was affected by soil temperature, soil moisture, root respiration and organic matter in four areas differing in vegetation cover. We specifically assessed the contribution of soil organic matter and fine root biomass (≤1 mm.) in soil carbon dioxide flux. The study area is located on the riverbanks of Henares River where it passes through the municipal term of Alcala de Henares (Madrid) in Central Spain. Measurements were performed in spring and autumn of 2009. The study was conducted on four different types of riparian vegetation: natural Mediterranean riparian forest, reforestation of 1994, reforestation of 1999 and riparian grassland without trees. In each area of study 3, 25x25 m, plots were delimited and within each plot three sampling units of 50x50 cm were selected at random. The temperature of the ground was taken during the measures from respiration using a Multi-thermometer (-50°C - +300°C) at 5 cm depth. The moisture content of the ground was measured at 5 cm of depth with a HH2 Moisture meter (Delta Devices, Cambridge, UK). The measures of respiration of the ground were realised in field by means of LCI portable (LC pro ADC Bioscientific, Ltd. UK) connected to a ground respiration camera. We introduced the camera 3 cm into the soil just after eliminating the vegetation grass of the surface of measurement cutting carefully the aerial part, without damaging the roots. Soil CO2 flux measurements were registered after stabilization. Immediately after CO2 measurements, we obtained soil samples by means of a drill of 2.18 cm of diameter taking samples to 10 cm and 20 cm depth. Soil samples were dried to the air with the aim of preserving the roots the sample contained. They were extracted manually by means of very fine tweezers. We separate roots by diameter (Fine roots ≤ 1mm; rest of roots > 1mm) and dead from alive using texture and colour as clues. Finally the dry weight of roots was taking with a precision balance +-0.0001. Soil organic matter to 10 and 20 cm of depth were measure in laboratory using the method of Walkley and Black (1934). Differences in Soil CO2 flux, organic matter, fine root biomass, temperature and moisture between areas were analyzed using one-way ANOVAs. Our results suggest that fine root biomass present a larger impact than soil organic matter in soil CO2 flux values. Natural riparian forest presented higher values of soil CO2 flux than the rest of areas even when differences in root biomass and soil organic matter were controlled. Between the grassy area and both reforestations there were no differences in soil CO2 flux. In addition, we found that soil CO2 flux in our study area was more affected by soil temperature than by moisture, which could be relevant in the interpretation of the possible effects of global change. Key words: riparian forest, fine roots, carbon cycle, soil CO2 flux, root respiration. Acknowledgements: Research projects, n°FP08-AG02 IMIDRA and RTA 2006-00101-00-00 INIA and predoctoral scholarship FPI-INIA.

Sources of nitric oxide and nitrous oxide following wetting of dry soil

NASA Technical Reports Server (NTRS)

Davidson, Eric A.

1992-01-01

A study is presented which is aimed at distinguishing among autotrophic nitrification, denitrification, and abiological processes as sources of NO and N2O production following wetting of dry soil. To distinguish among these processes, combinations of treatments in laboratory incubations of soil were used which included varying soil water content, autoclaving, C2H2 inhibition, and NO2(-) addition. Biological sources of NO and N2O commenced within minutes of wetting dry soil. Acetylene inhibition revealed that emissions of NO were dependent on nitrification, although a combination of NO2(-) production by nitrifiers and abiological reduction of NO2(-) to NO is also possible. NO emissions exceeded N2O emissions, and nitrification was the dominant source of both gases when soil water was below field capacity. It is concluded that NO emissions appear to be more important when good soil aeration favors nitrification, whereas N2O emissions appear more important when elevated soil water favors denitrification.

Arbuscular mycorrhizal fungi in arsenic-contaminated areas in Brazil.

PubMed

Schneider, Jerusa; Stürmer, Sidney Luiz; Guilherme, Luiz Roberto Guimarães; de Souza Moreira, Fatima Maria; Soares, Claudio Roberto Fonsêca de Sousa

2013-11-15

Arbuscular mycorrhizal fungi (AMF) are ubiquitous and establish important symbiotic relationships with the majority of the plants, even in soils contaminated with arsenic (As). In order to better understand the ecological relationships of these fungi with excess As in soils and their effects on plants in tropical conditions, occurrence and diversity of AMF were evaluated in areas affected by gold mining activity in Minas Gerais State, Brazil. Soils of four areas with different As concentrations (mg dm(-3)) were sampled: reference Area (10); B1 (subsuperficial layer) (396); barren material (573), and mine waste (1046). Soil sampling was carried out in rainy and dry seasons, including six composite samples per area (n = 24). AMF occurred widespread in all areas, being influenced by As concentrations and sampling periods. A total of 23 species were identified, belonging to the following genus: Acaulospora (10 species), Scutellospora (4 species), Racocetra (3 species), Glomus (4 species), Gigaspora (1 species) and Paraglomus (1 species). The most frequent species occurring in all areas were Paraglomus occultum, Acaulospora morrowiae and Glomus clarum. The predominance of these species indicates their high tolerance to excess As. Although arsenic contamination reduced AMF species richness, presence of host plants tended to counterbalance this reduction. Copyright © 2012 Elsevier B.V. All rights reserved.

A multiyear study of soil moisture patterns across agricultural and forested landscapes

NASA Astrophysics Data System (ADS)

Georgakakos, C. B.; Hofmeister, K.; O'Connor, C.; Buchanan, B.; Walter, T.

2017-12-01

This work compares varying spatial and temporal soil moisture patterns in wet and dry years between forested and agricultural landscapes. This data set spans 6 years (2012-2017) of snow-free soil moisture measurements across multiple watersheds and land covers in New York State's Finger Lakes region. Due to the relatively long sampling period, we have captured fluctuations in soil moisture dynamics across wetter, dryer, and average precipitation years. We can therefore analyze response of land cover types to precipitation under varying climatic and hydrologic conditions. Across the study period, mean soil moisture in forest soils was significantly drier than in agricultural soils, and exhibited a smaller range of moisture conditions. In the drought year of 2016, soil moisture at all sites was significantly drier compared to the other years. When comparing the effects of land cover and year on soil moisture, we found that land cover had a more significant influence. Understanding the difference in landscape soil moisture dynamics between forested and agricultural land will help predict watershed responses to changing precipitation patterns in the future.

Subsurface Salts in Antarctic Dry Valley Soils

NASA Technical Reports Server (NTRS)

Englert, P.; Bishop, J. L.; Gibson, E. K.; Koeberl, C.

2013-01-01

The distribution of water-soluble ions, major and minor elements, and other parameters were examined to determine the extent and effects of chemical weathering on cold desert soils. Patterns at the study sites support theories of multiple salt forming processes, including marine aerosols and chemical weathering of mafic minerals. Periodic solar-mediated ionization of atmospheric nitrogen might also produce high nitrate concentrations found in older sediments. Chemical weathering, however, was the major contributor of salts in Antarctic Dry Valleys. The Antarctic Dry Valleys represent a unique analog for Mars, as they are extremely cold and dry desert environments. Similarities in the climate, surface geology, and chemical properties of the Dry Valleys to that of Mars imply the possible presence of these soil formation mechanisms on Mars, other planets and icy satellites.

Assessing the stability in dry mycelial fertilizer of Penicillium chrysogenum as soil amendment via fluorescence excitation-emission matrix spectra: organic matter's transformation and maturity.

PubMed

Wang, Bing; Cai, Chen; Li, Guomin; Liu, Huiling

2017-12-01

Utilization as dry mycelial fertilizer (DMF) produced from penicillin fermentation fungi mycelium (PFFM) with an acid-heating pretreatment is a potential way. To study the transformation and stability of water-extractable organic matter in DMF-amended soil via fluorescence regional integration (FRI) of fluorescence excitation-emission matrix (EEM), a soil experiment in pot was carried out. The results showed that residual penicillin (about 32 mg/kg) was almost degraded in the first 5 days, indicating that the drug pollution was in control. The pH value, DOC, DON, and DOC/DON presented a classical profile, but germination index (GI) leveled off about 0.13 till day 13 in DMF-12% treatment due to the severe phytotoxicity. The addition of DMF significantly increased the soil microbial populations in contrast to the CON treatment. The EEM showed that the protein-like and microbial byproduct-like matters vanished on the 25th and 33rd days, whereas the fulvic-like substances appeared on the 7th day. The humic-like substances existed in original samples but their content greatly enhanced finally. The FRI results showed that P V, n /P III, n reached the highest value of 1.84 on the 25th day, suggesting that DMF maintained stable in amended soil. Because of its consistency with the results of GI and DOC/DON, the EEM-FRI has a potential to evaluate the stability of DMF in soil.

Evaluation of soil water stable isotope analysis by H2O(liquid)-H2O(vapor) equilibration method

NASA Astrophysics Data System (ADS)

Gralher, Benjamin; Stumpp, Christine

2014-05-01

Environmental tracers like stable isotopes of water (δ18O, δ2H) have proven to be valuable tools to study water flow and transport processes in soils. Recently, a new technique for soil water isotope analysis has been developed that employs a vapor phase being in isothermal equilibrium with the liquid phase of interest. This has increased the potential application of water stable isotopes in unsaturated zone studies as it supersedes laborious extraction of soil water. However, uncertainties of analysis and influencing factors need to be considered. Therefore, the objective of this study was to evaluate different methodologies of analysing stable isotopes in soil water in order to reduce measurement uncertainty. The methodologies included different preparation procedures of soil cores for equilibration of vapor and soil water as well as raw data correction. Two different inflatable sample containers (freezer bags, bags containing a metal layer) and equilibration atmospheres (N2, dry air) were tested. The results showed that uncertainties for δ18O were higher compared to δ2H that cannot be attributed to any specific detail of the processing routine. Particularly, soil samples with high contents of organic matter showed an apparent isotope enrichment which is indicative for fractionation due to evaporation. However, comparison of water samples obtained from suction cups with the local meteoric water line indicated negligible fractionation processes in the investigated soils. Therefore, a method was developed to correct the raw data reducing the uncertainties of the analysis.. We conclude that the evaluated method is advantageous over traditional methods regarding simplicity, resource requirements and sample throughput but careful consideration needs to be made regarding sample handling and data processing. Thus, stable isotopes of water are still a good tool to determine water flow and transport processes in the unsaturated zone.

Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

NASA Astrophysics Data System (ADS)

Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

2015-04-01

Water repellency (WR) is a property of some soils that inhibits or delays water infiltration between a few seconds and days or weeks. Inhibited or delayed infiltration contributes to ponding and increases runoff flow generation, often increasing soil erosion risk. In water-repellent soils, water infiltrates preferentially through cracks or macropores, causing irregular soil wetting patterns, the development of preferential flow paths and accelerated leaching of nutrients. Although low inputs of hydrophobic organic substances and high mineralization rates lead to low degrees of WR in cropped soils, it has been reported that conservative agricultural practices may induce soil WR. Although there are many studies at catchment, slope or plot scales very few studies have been carried out at particle or aggregate scale. Intra-aggregate heterogeneity of physical, biological and chemical properties conditions the transport of substances, microbial activity and biochemical processes, including changes in the amount, distribution and chemical properties of organic matter. Some authors have reported positive relationships between soil WR and aggregate stability, since it may delay the entry of water into aggregates, increase structural stability and contribute to reduce soil erosion risk. Organic C (OC) content, aggregate stability and WR are therefore strongly related parameters. In the case of agricultural soils, where both the type of management as crops can influence all these parameters, it is important to evaluate the interactions among them and their consequences. Studies focused on the intra-aggregate distribution of OC and WR are necessary to shed light on the soil processes at a detailed scale. It is extremely important to understand how the spatial distribution of OC in soil aggregates can protect against rapid water entry and help stabilize larger structural units or lead to preferential flow. The objectives of this research are to study [i] the OC content and the intensity of WR in aggregates of different sizes. [ii] the intra-aggregate distribution of OC and the intensity of WR and [iii] the structural stability of soil aggregates relative to the OC content and the intensity of WR in soils under different crops (apricot, citrus and wheat) and different treatments (conventional tilling and mulching). Soil samples were collected from an experimental area (Luvic Calcisols and Calcic Luvisols) in the province of Sevilla (Southern Spain) under different crops (apricot, citrus and wheat) and different management types (conventional tillage with moldboard plow) and mulching (no-tilling and addition of wheat residues at rates varying between 5 and 8 Mg/ha/year). At each sampling site, soil blocks (50 cm long × 50 cm wide × 10 cm deep) were carefully collected to avoid disturbance of aggregates as much as possible and transported to the laboratory. At field moist condition, undisturbed soil aggregates were separated by hand. In order to avoid possible interferences due to disturbance by handling, aggregates broken during this process were discarded. Individual aggregates were arranged in paper trays and air-dried during 7 days under laboratory standard conditions. After air-drying, part of each sample was carefully divided for different analyses: [i] part of the original samples was sieved (2 mm) to eliminate coarse soil particles and homogenized for characterization of OC and N contents, C/N ratio and texture; [ii] part of the aggregates were dry-sieved (0.25-0.5, 0.5-1 and 1-2 mm) or measured with a caliper (2-5, 5-10 and 10-15 mm) and separated in different sieve-size classes for determination of WR and OC content; [iii] aggregates 10-15 mm in size were selected for obtaining aggregate layers using a soil aggregate erosion (SAE) apparatus and WR and OC content were determined at each layer; finally, [iv] in order to study the relation between stability to slaking, WR and OC, these properties were determined in 90 air-dried aggregates (about 10 mm in size) selected per treatment (mulched or conventional tillage) and crop (apricot, citrus and wheat). In this case, every set of aggregates was randomly divided in three groups (n = 30) for assessing stability to slaking, WR and OC, respectively. OC content in the fine earth fraction of soils under different crops did not show important variations, although it increased significantly from conventionally tilled to mulched soils. The distribution of OC content in aggregates with different size varied among soils under different crops, generally increasing with decreasing size. At the intra-aggregate level, OC concentrated preferably in the exterior layer of differently sized aggregates and of aggregate coatings and interior from conventionally tilled soils, probably because of recent organic inputs or leachates. In the case of mulched soils, higher concentrations were observed, but no significant differences among aggregate regions were found. The intensity of water repellency, determined by the ethanol method, did not show great variations among differently sized aggregates under different crops in the 0-10 cm layer, but increased significantly from conventionally tilled to mulched soils. Coarser aggregates were generally wettable, while finer aggregates showed slight water repellency. Regardless of variations in the distribution of OC in different layers of aggregate from conventionally tilled soils, great or significant differences in the distribution of water repellency at the intra-aggregate level were not found. In case of mulched soils such differences were not significant. Finally, the intensity of water repellency was much more important than the concentration of OC in the stability to slaking of aggregates.

Biogeochemical Relationships of a Subtropical Dry Forest on Karst

Treesearch

E. Medina; E. Cuevas; H. Marcano-Vega; E. Meléndez-Ackerman; E.H. Helmer

2017-01-01

Tropical dry forests on calcareous substrate constitute the main vegetation cover in many islands of the Caribbean. Dry climate and nutrient scarcity in those environments are ideal to investigate the potential role of high levels of soil calcium (Ca) in regulating plant selection and productivity. We analyzed the elemental composition of soil, loose litter, and leaf...

Quantifying the influence of deep soil moisture on ecosystem albedo: the role of vegetation Zulia M. Sánchez-Mejía 1 and Shirley A. Papuga1 1School of Natural Resources and the Environment, University of Arizona, Tucson, AZ

NASA Astrophysics Data System (ADS)

Sanchez-Mejia, Z. M.; Papuga, S. A.

2012-12-01

Water limited ecosystems in arid and semiarid regions are characterized by sparse vegetation and a relatively large fraction of bare soil. Importantly, the land surface in these dryland regions is highly sensitive to pulses of moisture that affect the vegetation canopy in density and color, as well as the soil color. Changes in surface conditions due to these pulses have been shown to affect the surface energy fluxes and atmospheric processes in these regions. For instance, previous studies have shown that shallow soil moisture ( < 20 cm below the surface) significantly changes surface albedo (a= SWup/ SWin). Recent studies have highlighted the importance of deep soil moisture ( > 20 cm below the surface) for vegetation dynamics in these regions. We hypothesize that deep soil moisture will change vegetation canopy density and color enough that changes in albedo will be observable at the surface, therefore linking deep soil moisture and albedo. We adopt a conceptual framework to address this hypothesis, where at any point in time the soil profile falls into one of four cases: (1) dry shallow soil and dry deep soil; (2) wet shallow soil and dry deep soil; (3) wet shallow soil and wet deep soil; and (4) dry shallow soil and wet deep soil. At a creosotebush dominated ecosystem of the Santa Rita Experimental Range, southern Arizona during summers of 2011 and 2012, we took albedo measurements during these cases at multiple bare and vegetated patches within the footprint of an eddy covariance tower. We found that when the soil is completely dry (Case 1) albedo is highest in both bare and vegetated patches. Likewise, when the soil is wet in both the shallow and deep regions (Case 3), albedo is lowest in both bare and vegetated patches. Interestingly, we also found that albedo is significantly lower for vegetated patches when the deep soil is wet and shallow soil is dry (Case 4). These results imply that deep soil moisture can be important in altering ecosystem level albedo. We note that ecosystems with higher percent vegetative cover are likely to be more sensitive to deep soil moisture driven changes in albedo. To quantify the influence of percent cover on ecosystem albedo, we populate a 100 x 100 cell grid randomly with bare and vegetated cells. For each case, we assign an albedo value to each cell based on probability distribution functions (PDFs) of soil moisture and albedo created from our field campaign data. Using this technique we can identify for each soil moisture case at which point the percent vegetative cover will significantly influence ecosystem albedo. Quantitative analyses of these ecosystem interactions help identify the unique role of deep soil moisture in land surface - atmosphere interactions.

Quantification of rock slope terrain properties

NASA Astrophysics Data System (ADS)

Volkwein, Axel; Gerber, Werner

2017-04-01

Rockfall trajectory simulation codes need information on the terrain properties to formulate appropriate rebound models. Usually, the manuals of rockfall simulation codes give sketches or photographs of terrain samples [1,2]. Based on these the user can select suitable terrains for the simulation area. We now would like to start a discussion whether it is possible to numerically quantify the terrain properties which would make the ground assignment more objective. Different ground properties play a role for the interaction between a falling rock and the ground: • Elastic deformation • plastic deformation • Energy absorption • friction • hardness • roughness • surface vs. underground • etc. The question is now whether it is possible to quantify above parameters and to finally provide tables that contain appropriate simulation parameters. In a first attempt we suggest different methods or parameters that might be evaluated in situ: • Small scale drop tests • Light weight deflectometer (LWD) • Particle sizes • Sliding angle • Particle distribution • Soil cover • Water content Of course, above measurements will never perfectly fit to different mountain slopes. However, if a number of measurements has been made their spreading will give an idea on the natural variability of the ground properties. As an example, the following table gives an idea on how the ME and Evd values vary for different soils. Table 1: LWD measurements on different soil types [3] Ground type Soil layer Soil humidityEvd (median)σ (median)Evd (average) Humus-carb. < 10cm dry 17.4 6.8 15.6 Regosol 10 - 30cm dry 8.6 3.9 9.4 Brownish 30 - 50cm dry 12.1 3.2 11.7 Calcaric 30 - 50cm dry 7.5 3.3 7.0 Acid brownish70 - 100cmdry 7.8 2.1 7.7 Fahlgley 10 - 30cm dry 9.2 4.0 7.7 References [1] Bartelt P et al (2016) RAMMS::rockfall user manual v1.6. SLF, Davos. [2] Dorren L.K.A., 2015. Rockyfor3D (v5.2) revealed - Transparent description of the complete 3D rockfall model. ecorisQ paper (www.ecorisq.org): 32 p. [3] Hoffmann P. (2015) Härte von Böden. Bsc thesis, ZHAW Waedenswil.

Assessment of Agroforestry Trees in Dry-land Savanna Supports Ecohydrologic Separation

NASA Astrophysics Data System (ADS)

Ceperley, Natalie; Mande, Theophile; Van de Giesen, Nick; Tyler, Scott; Parlange, Marc

2016-04-01

We use stable isotopes of water to demonstrate the ecohydrologic separation, or the plant controlled compartmentalization, of different water sources in a catchment in South Eastern Burkina Faso. We analyze water extracted from the groundwater, stream water, precipitation, perched aquifer, xylem water of agroforestry trees, and sub-canopy soil water over a 6 year period to explore how the separation affects different components of the system over time. The ratio between deuterium and O18 allows us to assess whether the water that plants use is the same as the water that recharges the aquifer and runs off in the stream. Water extracted from the tree at leaf out in February corresponded to deuterium and O18 concentrations of the groundwater, a drop from its dry season, enriched, levels which mimicked the soil water. Examination of the isotopic signature suggests that the size of tree plays an important role in duration and timing of this leaf-out as well as the degree of enrichment during the peak of the dry season. Dates of leaf out were confirmed by analyzing sub-canopy radiation and photographs. Water extracted from roots suggests that the trees are performing hydraulic redistribution, or lifting the ground water and 'sharing it' with the rooting zone soil during the dry season. The enriched level of xylem, in this case, is a product of water loss and enrichment along the travel path of the water from the roots to the tip of the branch, as evidenced by the variation according to size of tree. Vapor pressure deficit, sap flow, soil water, and soil moisture interactions support this picture of interacting controls, separate from hydrologic triggers on the water movement in the tree. A second round of sampling focused on the leaf out period by extracting and analyzing stem water from throughout the canopy during the leaf out. Simultaneous large eddy correlation revealed high levels of latent energy flux, even during the dry season. Our isotope analysis allowed us to conclude that tree level transpiration explains this discrepancy since it does not access the same reservoirs of water as the rest of the catchment. Most current land surface models do not differentiate between different reservoirs of water.

Contrasted response of colloidal, organic and inorganic dissolved phosphorus forms during rewetting of dried riparian soils

NASA Astrophysics Data System (ADS)

Gu, Sen; Gruau, Gérard; Malique, François; Dupas, Rémi; Gascuel-Odoux, Chantal; Petitjean, Patrice; Bouhnik-Le Coz, Martine

2017-04-01

Riparian vegetated buffer strip (RVBS) are currently used to protect surface waters from phosphorus (P) emissions because of their ability to retain P-enriched soil particles. However, this protection role may be counterbalanced by the development in these zones of conditions able to trigger the release of highly mobile dissolved or colloidal P forms. Rewetting after drying is one of these conditions. So far, the potential sources of P mobilized during rewetting after drying are not clearly identified, nor are clearly identified the chemical nature of the released dissolved P species, or the role of the soil P speciation on these forms. In this study, two riparian soils (G and K) showing contrasting soil P speciation (65% of inorganic P species in soil G, as against 70% of organic P) were submitted to three successive dry/wet cycles in the laboratory. Conventional colorimetric determination of P concentrations combined with ultrafiltration, and measurements of iron (Fe) and aluminum (Al) and dissolved organic carbon (DOC) contents using ICP-MS and TOC analyzers, respectively, were used to study the response of the different P forms to rewetting after drying and also their release kinetics during soil leaching. For both soils, marked P release peaks were observed at the beginning of each wet cycles, with the organic-rich K soils giving, however, larger peaks than the inorganic one (G soil). For both soils also, concentrations in molybdate reactive P (MRP) remained quite constant throughout each leaching episode, contrary to the molybdate unreactive P (MUP) concentrations which were high immediately after rewetting and then decreased rapidly during leaching. A speciation change was observed from the beginning to the end of all leaching cycles. Colloidal P was found to be a major fraction of the total P immediately after rewetting (up to 50-70%) and then decreased to the end of each wet cycle where most of the eluted P was true dissolved inorganic P. Colloidal-P exhaustion was tightly associated with DOC, Fe and Al exhaustions. Colloids were larger in size at the beginning than at the end of all cycles. Peak at the beginning of each wet cycles remained quite constant even after two drying/leaching cycles, evidencing the existence of mechanisms able to rebuild a pool of leachable P during drying process. Thus, there was clearly a control of soil characteristics on the released P forms in leachates. Colloidal P carriers appeared to consist of Fe and/or Al oxyhydroxide nano/microparticles associated with organic matter. Most importantly, a survey of colloidal size distribution during leaching indicated that the rapidly exhausted MUP pool consisted of larger size MUP and colloidal P phases, which probably originated from soil macropores, while the relatively infinite MRP pool consisted of smaller size colloidal P and true dissolved MRP phases, which was mobilized from soil micropores. These results further demonstrate the ability of rewetting after drying to lead to pulses of dissolved and colloidal P in riparian soils, thereby evidencing the risks that P-enriched soil particles accumulated in RVBS could constitute a long-term threat for surface water.