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Sample records for alkaline soil conditions

  1. Speciation and Release Kinetics of Cadmium in an Alkaline Paddy Soil Under Various Flooding Periods and Draining Conditions

    SciTech Connect

    S Khaokaew; R Chaney; G Landrot; M Ginder-Vogel; D Sparks

    2011-12-31

    This study determined Cd speciation and release kinetics in a Cd-Zn cocontaminated alkaline paddy soil, under various flooding periods and draining conditions, by employing synchrotron-based techniques, and a stirred-flow kinetic method. Results revealed that varying flooding periods and draining conditions affected Cd speciation and its release kinetics. Linear least-squares fitting (LLSF) of bulk X-ray absorption fine structure (XAFS) spectra of the air-dried, and the 1 day-flooded soil samples, showed that at least 50% of Cd was bound to humic acid. Cadmium carbonates were found as the major species at most flooding periods, while a small amount of cadmium sulfide was found after the soils were flooded for longer periods. Under all flooding and draining conditions, at least 14 mg/kg Cd was desorbed from the soil after a 2-hour desorption experiment. The results obtained by micro X-ray fluorescence ({mu}-XRF) spectroscopy showed that Cd was less associated with Zn than Ca, in most soil samples. Therefore, it is more likely that Cd and Ca will be present in the same mineral phases rather than Cd and Zn, although the source of these two latter elements may originate from the same surrounding Zn mines in the Mae Sot district.

  2. Yield performance of cowpea genotypes grown in alkaline soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cowpea or Southernpea [Vigna unguiculata (L.) Walp.] is an important legume crop used as a feed for livestock, as a green vegetable and for consumption of its dry beans which provide 22-25% protein. The crop is very sensitive to alkaline soil conditions. When grown at soil pH of 7.5 or higher, cowp...

  3. Field screening of cowpea cultivars for alkaline soil tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cowpea or Southernpea [Vigna unguiculata (L.) Walp.] is an important legume crop used as a feed for livestock, as a green vegetable and for consumption of its dry beans which provide 22-25% protein. The crop is very sensitive to alkaline soil conditions. When grown at soil pH of 7.5 or higher, cowp...

  4. Microbial Thiocyanate Utilization under Highly Alkaline Conditions

    PubMed Central

    Sorokin, Dimitry Y.; Tourova, Tatyana P.; Lysenko, Anatoly M.; Kuenen, J. Gijs

    2001-01-01

    Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS−) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase

  5. Microbial thiocyanate utilization under highly alkaline conditions.

    PubMed

    Sorokin, D Y; Tourova, T P; Lysenko, A M; Kuenen, J G

    2001-02-01

    Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS-) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase

  6. Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities.

    PubMed

    Khodadoust, Amid P; Theis, Thomas L; Murarka, Ishwar P; Naithani, Pratibha; Babaeivelni, Kamel

    2013-12-01

    The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.0, while representative coal fly ash samples from two different locations in the coal fly ash impoundment were used to produce two alkaline ash leachates with pH 7.4 and 8.2. The arsenic found in the ash leachates was present as arsenate [As(V)]. Adsorption isotherm experiments were carried out to determine the adsorption parameters required for predicting the uptake of arsenic from the ash leachates. For all soils and leachates, the adsorption of arsenic followed the Langmuir and Freundlich equations, indicative of the favorable adsorption of arsenic from leachates onto all soils. The uptake of arsenic was evaluated as a function of ash leachate characteristics and the soil components. The uptake of arsenic from alkaline ash leachates, which occurred mainly as calcium hydrogen arsenate, increased with increasing clay fraction of soil and with increasing soil organic matter of the alkaline soils. Appreciable uptake of arsenic from alkaline ash leachates with different pH and arsenic concentration was observed for the alkaline soils, thus attenuating the contamination of groundwater downstream of the retired coal fly ash impoundment.

  7. Predicting Phosphorus Release from Anaerobic, Alkaline, Flooded Soils.

    PubMed

    Amarawansha, Geethani; Kumaragamage, Darshani; Flaten, Don; Zvomuya, Francis; Tenuta, Mario

    2016-07-01

    Anaerobic conditions induced by prolonged flooding often lead to an enhanced release of phosphorus (P) to floodwater; however, this effect is not consistent across soils. This study aimed to develop an index to predict P release potential from alkaline soils under simulated flooded conditions. Twelve unamended or manure-amended surface soils from Manitoba were analyzed for basic soil properties, Olsen P (Ols-P), Mehlich-3 extractable total P (M3P), Mehlich-3 extractable molybdate-reactive P (M3P), water extractable P (WEP), soil P fractions, single-point P sorption capacity (P), and Mehlich-3 extractable Ca (M3Ca), and Mg (M3Mg). Degree of P saturation (DPS) was calculated using Ols-P, M3P or M3P as the intensity factor, and an estimated adsorption maximum based on either P or M3Ca + M3Mg as the capacity factor. To develop the model, we used the previously reported floodwater dissolved reactive P (DRP) concentration changes during 8 wk of flooding for the same unamended and manured soils. Relative changes in floodwater DRP concentration (DRP), calculated as the ratio of maximum to initial DRP concentration, ranged from 2 to 15 across ten of the soils, but were ≤1.5 in the two soils with the greatest clay content. Partial least squares analysis indicated that DPS3 calculated using M3P as the intensity factor and (2 × P) + M3P as the capacity factor with clay percentage can effectively predict DRP ( = 0.74). Results suggest that P release from a soil to floodwater may be predicted using simple and easily measurable soil properties measured before flooding, but validation with more soils is needed. PMID:27380097

  8. A study of the efficiency of edible oils degraded in alkaline conditions by Pseudomonas aeruginosa SS-219 and Acinetobacter sp. SS-192 bacteria isolated from Japanese soil.

    PubMed

    Sugimori, Daisuke; Utsue, Tomohiro

    2012-03-01

    High lipid concentration contained in wastewater inhibits the activity of microorganisms in biological wastewater treatment systems such as activated sludge and methane fermentation. To reduce the inhibitory effects, microorganisms capable of efficiently degrading edible oils were screened from various environmental sources. From Japanese soil, we isolated 2 bacteria strains with high degradation abilities at an alkaline pH without consumption of biological oxygen demand (BOD) constituents. Acinetobacter sp. strain SS-192 and Pseudomonas aeruginosa strain SS-219 degraded 77.5 ± 0.6% and 89.5 ± 1.5%, respectively, of 3,000 ppm of mixed oil consisting of salad oil/lard/beef tallow (1/1/1, w/w/w) at 37°C and pH 9.0 in 24 h. Efficient degradation by the two strains occurred at pH 8-9 and 25-40°C. Strain SS-219 degraded lipids even at pH 3. The degradation rate of 3,000 ppm of salad oil, lard, and beef tallow by strain SS-192 was 79.9 ± 2.6%, 63.6 ± 1.9%, and 70.1 ± 1.2%, respectively, during a 24-h cultivation. The degradation rate of 3,000 ppm of salad oil, lard, and beef tallow by strain SS-219 was 82.3 ± 2.1%, 71.9 ± 2.2%, and 71.0 ± 1.1%, respectively, during a 24-h cultivation. After mixed oil degradation by both strains, the BOD value of the cell culture increased from 2,100 ppm to 3,200-4,000 ppm. The fact that neither strain utilizes BOD ingredients will be beneficial to pretreatment of methane fermentation systems such as upflow anaerobic sludge blanket reactors. In addition, the growth of usual heterotrophic microorganisms utilizing soluble BOD can be suppressed under alkaline pH. PMID:22805803

  9. On the apparent CO2 absorption by alkaline soils

    NASA Astrophysics Data System (ADS)

    Chen, X.; Wang, W. F.

    2014-02-01

    Alkaline soils in the Gubantonggut Desert were recently demonstrated socking away large quantities of CO2 in an abiotic form. This demands a better understanding of abiotic CO2 exchange in alkaline sites. Reaction of CO2 with the moisture or dew in the soil was conjectured as a potential mechanism. The main goal of this study is to determine the extent to which the dew deposition modulates Land-Atmosphere CO2 exchange at highly alkaline sites (pH ~ 10). Experiments were conducted at the most barren sites (canopy coverage < 5%) to cut down uncertainty. Dew quantities and soil CO2 fluxes were measured using a micro-lysimeters and an automated flux system (LI-COR, Lincoln, Nebraska, USA), respectively. There is an evident increase of dew deposition in nocturnal colder temperatures and decrease in diurnal warmer temperatures. Variations of soil CO2 flux are almost contrary, but the increase in diurnal warmer temperatures is obscure. It was shown that the accumulation and evaporation of dew in the soil motivates the apparent absorption and release of CO2. It was demonstrated that dew amounts in the soil has an exponential relation with the part in Fc beyond explanations of the worldwide utilized Q10 model. Therefore dew deposition in highly alkaline soils exerted a potential CO2 sink and can partly explain the apparent CO2 absorption. This implied a crucial component in the net ecosystem carbon balance (NECB) at alkaline sites which occupies approximately 5% of the Earth's land surface (7 million km). Further explorations for its mechanisms and representativeness over other arid climate systems have comprehensive perspectives in the quaternary research.

  10. Phosphorus Mobilization from Manure-Amended and Unamended Alkaline Soils to Overlying Water during Simulated Flooding.

    PubMed

    Amarawansha, E A G S; Kumaragamage, D; Flaten, D; Zvomuya, F; Tenuta, M

    2015-07-01

    Anaerobic soil conditions resulting from flooding often enhance release of phosphorus (P) to overlying water. Enhanced P release is well documented for flooded acidic soils; however, there is little information for flooded alkaline soils. We examined the effect of flooding and anaerobic conditions on P mobilization using 12 alkaline soils from Manitoba that were either unamended or amended with solid cattle manure. Pore water and floodwater were analyzed over 8 wk of simulated flooding for dissolved reactive P (DRP), Ca, Mg, Fe, and Mn. As expected, manured soils had significantly greater pore and floodwater DRP concentrations than unamended. Flooding increased pore water DRP concentrations significantly in all soils and treatments except one manured clay in which concentrations increased initially and then decreased. Floodwater DRP concentrations increased significantly by two- to 15-fold in 10 soils regardless of amendment treatment but remained relatively stable in the two soils with greatest clay content. Phosphorus release at the onset of flooding was associated with the release of Ca, Mg, and Mn, suggesting that P release may be controlled by the dissolution of Mg and Ca phosphates and reductive dissolution of Mn phosphates. Thereafter, P release was associated with release of Fe, suggesting the reductive dissolution of Fe phosphates. Differences in pore water and floodwater DRP concentrations among soils and amendment treatments and the high variability in P mobilization from pore water to floodwater among soils indicate the need to further investigate chemical reactions responsible for P release and mobility under anaerobic conditions. PMID:26437107

  11. Phosphorus Mobilization from Manure-Amended and Unamended Alkaline Soils to Overlying Water during Simulated Flooding.

    PubMed

    Amarawansha, E A G S; Kumaragamage, D; Flaten, D; Zvomuya, F; Tenuta, M

    2015-07-01

    Anaerobic soil conditions resulting from flooding often enhance release of phosphorus (P) to overlying water. Enhanced P release is well documented for flooded acidic soils; however, there is little information for flooded alkaline soils. We examined the effect of flooding and anaerobic conditions on P mobilization using 12 alkaline soils from Manitoba that were either unamended or amended with solid cattle manure. Pore water and floodwater were analyzed over 8 wk of simulated flooding for dissolved reactive P (DRP), Ca, Mg, Fe, and Mn. As expected, manured soils had significantly greater pore and floodwater DRP concentrations than unamended. Flooding increased pore water DRP concentrations significantly in all soils and treatments except one manured clay in which concentrations increased initially and then decreased. Floodwater DRP concentrations increased significantly by two- to 15-fold in 10 soils regardless of amendment treatment but remained relatively stable in the two soils with greatest clay content. Phosphorus release at the onset of flooding was associated with the release of Ca, Mg, and Mn, suggesting that P release may be controlled by the dissolution of Mg and Ca phosphates and reductive dissolution of Mn phosphates. Thereafter, P release was associated with release of Fe, suggesting the reductive dissolution of Fe phosphates. Differences in pore water and floodwater DRP concentrations among soils and amendment treatments and the high variability in P mobilization from pore water to floodwater among soils indicate the need to further investigate chemical reactions responsible for P release and mobility under anaerobic conditions.

  12. phoD Alkaline Phosphatase Gene Diversity in Soil.

    PubMed

    Ragot, Sabine A; Kertesz, Michael A; Bünemann, Else K

    2015-10-01

    Phosphatase enzymes are responsible for much of the recycling of organic phosphorus in soils. The PhoD alkaline phosphatase takes part in this process by hydrolyzing a range of organic phosphoesters. We analyzed the taxonomic and environmental distribution of phoD genes using whole-genome and metagenome databases. phoD alkaline phosphatase was found to be spread across 20 bacterial phyla and was ubiquitous in the environment, with the greatest abundance in soil. To study the great diversity of phoD, we developed a new set of primers which targets phoD genes in soil. The primer set was validated by 454 sequencing of six soils collected from two continents with different climates and soil properties and was compared to previously published primers. Up to 685 different phoD operational taxonomic units were found in each soil, which was 7 times higher than with previously published primers. The new primers amplified sequences belonging to 13 phyla, including 71 families. The most prevalent phoD genes identified in these soils were affiliated with the orders Actinomycetales (13 to 35%), Bacillales (1 to 29%), Gloeobacterales (1 to 18%), Rhizobiales (18 to 27%), and Pseudomonadales (0 to 22%). The primers also amplified phoD genes from additional orders, including Burkholderiales, Caulobacterales, Deinococcales, Planctomycetales, and Xanthomonadales, which represented the major differences in phoD composition between samples, highlighting the singularity of each community. Additionally, the phoD bacterial community structure was strongly related to soil pH, which varied between 4.2 and 6.8. These primers reveal the diversity of phoD in soil and represent a valuable tool for the study of phoD alkaline phosphatase in environmental samples.

  13. phoD Alkaline Phosphatase Gene Diversity in Soil

    PubMed Central

    Kertesz, Michael A.; Bünemann, Else K.

    2015-01-01

    Phosphatase enzymes are responsible for much of the recycling of organic phosphorus in soils. The PhoD alkaline phosphatase takes part in this process by hydrolyzing a range of organic phosphoesters. We analyzed the taxonomic and environmental distribution of phoD genes using whole-genome and metagenome databases. phoD alkaline phosphatase was found to be spread across 20 bacterial phyla and was ubiquitous in the environment, with the greatest abundance in soil. To study the great diversity of phoD, we developed a new set of primers which targets phoD genes in soil. The primer set was validated by 454 sequencing of six soils collected from two continents with different climates and soil properties and was compared to previously published primers. Up to 685 different phoD operational taxonomic units were found in each soil, which was 7 times higher than with previously published primers. The new primers amplified sequences belonging to 13 phyla, including 71 families. The most prevalent phoD genes identified in these soils were affiliated with the orders Actinomycetales (13 to 35%), Bacillales (1 to 29%), Gloeobacterales (1 to 18%), Rhizobiales (18 to 27%), and Pseudomonadales (0 to 22%). The primers also amplified phoD genes from additional orders, including Burkholderiales, Caulobacterales, Deinococcales, Planctomycetales, and Xanthomonadales, which represented the major differences in phoD composition between samples, highlighting the singularity of each community. Additionally, the phoD bacterial community structure was strongly related to soil pH, which varied between 4.2 and 6.8. These primers reveal the diversity of phoD in soil and represent a valuable tool for the study of phoD alkaline phosphatase in environmental samples. PMID:26253682

  14. DNA-based determination of microbial biomass suitable for frozen and alkaline soil samples

    NASA Astrophysics Data System (ADS)

    Semenov, Mikhail; Blagodatskaya, Evgeniya; Kogut, Boris; Kuzyakov, Yakov

    2015-04-01

    Microbial biomass is a sensitive indicator of changes due to soil management, long before other basic soil measures such as Corg or Ntot. Improvement of methods for determination of microbial biomass still remains relevant, and these methods should be correctly applicable for the soil samples being in various state. This study was designed to demonstrate the applicability of DNA-based determination of microbial biomass under conditions when the common basic approaches, namely chloroform fumigation-extraction (CFE) and substrate-induced respiration (SIR), are restricted by certain soil properties, experimental designs or research needs, e.g. in frozen, alkaline or carbonaceous soils. We compared microbial biomass determined by CFE, SIR and by DNA approaches in the range of neutral and slightly alkaline Chernozem and alkaline Calcisol of semi-arid climate. The samples of natural and agricultural ecosystems were taken throughout the soil profile from long-term static field experiments in the European part of Russia. Extraction and subsequent quantification of dsDNA revealed a strong agreement with SIR and CFE when analyzing the microbial biomass content in soils with pH below 8. The conversion factors (FDNA) from dsDNA to SIR-Cmic (5.10) and CFE-Cmic (4.41) were obtained by testing a range of the soil samples down to 1.5 m depth and indicated a good reproducibility of DNA-based estimations. In alkaline soils (pH > 8), CO2 retention due to alkaline pH and exchange with carbonates resulted in a strong underestimation of soil microbial biomass by SIR or even in the absence of any CO2 emission, especially at low absolute values of microbial biomass in subsoil. Correction of CO2 efflux by theoretical retention pH-dependent factors caused overestimation of SIR-biomass. In alkaline conditions, DNA extraction proved to be a reliable alternative for microbial biomass determination. Moreover, the DNA-based approach can serve as an excellent alternative enabling correct

  15. Archaeal Communities in a Heterogeneous Hypersaline-Alkaline Soil

    PubMed Central

    Navarro-Noya, Yendi E.; Valenzuela-Encinas, César; Sandoval-Yuriar, Alonso; Jiménez-Bueno, Norma G.; Marsch, Rodolfo

    2015-01-01

    In this study the archaeal communities in extreme saline-alkaline soils of the former lake Texcoco, Mexico, with electrolytic conductivities (EC) ranging from 0.7 to 157.2 dS/m and pH from 8.5 to 10.5 were explored. Archaeal communities in the 0.7 dS/m pH 8.5 soil had the lowest alpha diversity values and were dominated by a limited number of phylotypes belonging to the mesophilic Candidatus Nitrososphaera. Diversity and species richness were higher in the soils with EC between 9.0 and 157.2 dS/m. The majority of OTUs detected in the hypersaline soil were members of the Halobacteriaceae family. Novel phylogenetic branches in the Halobacteriales class were detected in the soil, and more abundantly in soil with the higher pH (10.5), indicating that unknown and uncharacterized Archaea can be found in this soil. Thirteen different genera of the Halobacteriaceae family were identified and were distributed differently between the soils. Halobiforma, Halostagnicola, Haloterrigena, and Natronomonas were found in all soil samples. Methanogenic archaea were found only in soil with pH between 10.0 and 10.3. Retrieved methanogenic archaea belonged to the Methanosarcinales and Methanomicrobiales orders. The comparison of the archaeal community structures considering phylogenetic information (UniFrac distances) clearly clustered the communities by pH. PMID:26074731

  16. Archaeal Communities in a Heterogeneous Hypersaline-Alkaline Soil.

    PubMed

    Navarro-Noya, Yendi E; Valenzuela-Encinas, César; Sandoval-Yuriar, Alonso; Jiménez-Bueno, Norma G; Marsch, Rodolfo; Dendooven, Luc

    2015-01-01

    In this study the archaeal communities in extreme saline-alkaline soils of the former lake Texcoco, Mexico, with electrolytic conductivities (EC) ranging from 0.7 to 157.2 dS/m and pH from 8.5 to 10.5 were explored. Archaeal communities in the 0.7 dS/m pH 8.5 soil had the lowest alpha diversity values and were dominated by a limited number of phylotypes belonging to the mesophilic Candidatus Nitrososphaera. Diversity and species richness were higher in the soils with EC between 9.0 and 157.2 dS/m. The majority of OTUs detected in the hypersaline soil were members of the Halobacteriaceae family. Novel phylogenetic branches in the Halobacteriales class were detected in the soil, and more abundantly in soil with the higher pH (10.5), indicating that unknown and uncharacterized Archaea can be found in this soil. Thirteen different genera of the Halobacteriaceae family were identified and were distributed differently between the soils. Halobiforma, Halostagnicola, Haloterrigena, and Natronomonas were found in all soil samples. Methanogenic archaea were found only in soil with pH between 10.0 and 10.3. Retrieved methanogenic archaea belonged to the Methanosarcinales and Methanomicrobiales orders. The comparison of the archaeal community structures considering phylogenetic information (UniFrac distances) clearly clustered the communities by pH.

  17. Effect of common ions on nitrate removal by zero-valent iron from alkaline soil.

    PubMed

    Tang, Cilai; Zhang, Zengqiang; Sun, Xining

    2012-09-15

    Zero-valent iron (Fe(0))-based permeable reactive barrier (PRB) technology has been proved to be effective for soil and groundwater nitrate remediation under acidic or near neutral conditions. But few studies have been reported about it and the effects of coexistent ions under alkaline conditions. In this study, nitrate reduction by Fe(0) was evaluated via batch tests in the presence of alkaline soil and common cation (Fe(2+), Fe(3+) and Cu(2+)) and anion (citrate, oxalate, acetate, SO(4)(2-), PO(4)(3-), Cl(-) and HCO(3)(-)). The results showed that cation significantly enhanced nitrate reduction with an order of Fe(3+)>Fe(2+)>Cu(2+) due to providing Fe(2+) directly or indirectly. Most anions enhanced nitrate reduction, but PO(4)(3-) behaved inhibition. The promotion decreased in the order of citrate>acetate>SO(4)(2-)>Cl(-)≈HCO(3)(-)≈oxalate≫PO(4)(3-). Ammonium was the major final product from nitrate reduction by Fe(0), while a little nitrite accumulated in the beginning of reaction. The nitrogen recovery in liquid and gas phase was only 56-78% after reaction due to ammonium adsorption onto soil. The solution pH and electric conductivity (EC) varied depending on the specific ion added. The results implied that PRB based Fe(0) is a potential approach for in situ remediation of soil and groundwater nitrate contamination in the alkaline conditions.

  18. Silicon improves maize photosynthesis in saline-alkaline soils.

    PubMed

    Xie, Zhiming; Song, Ri; Shao, Hongbo; Song, Fengbin; Xu, Hongwen; Lu, Yan

    2015-01-01

    The research aimed to determine the effects of Si application on photosynthetic characteristics of maize on saline-alkaline soil, including photosynthetic rate (P n ), stomatal conductance (g s ), transpiration rate (E), and intercellular CO2 concentration (C i ) of maize in the field with five levels (0, 45, 90, 150, and 225 kg · ha(-1)) of Si supplying. Experimental results showed that the values of P n, g s, and C i of maize were significantly enhanced while the values of E of maize were dramatically decreased by certain doses of silicon fertilizers, which meant that Si application with proper doses significantly increased photosynthetic efficiency of maize in different growth stages under stressing environment of saline-alkaline soil. The optimal dose of Si application in this experiment was 150 kg · ha(-1) Si. It indicated that increase in maize photosynthesis under saline-alkaline stress took place by Si application with proper doses, which is helpful to improve growth and yield of maize. PMID:25629083

  19. Microsymbionts of Phaseolus vulgaris in acid and alkaline soils of Mexico.

    PubMed

    Verástegui-Valdés, Myrthala M; Zhang, Yu Jing; Rivera-Orduña, Flor N; Cheng, Hai-Ping; Sui, Xing Hua; Wang, En Tao

    2014-12-01

    In order to investigate bean-nodulating rhizobia in different types of soil, 41 nodule isolates from acid and alkaline soils in Mexico were characterized. Based upon the phylogenetic studies of 16S rRNA, atpD, glnII, recA, rpoB, gyrB, nifH and nodC genes, the isolates originating from acid soils were identified as the phaseoli symbiovar of the Rhizobium leguminosarum-like group and Rhizobium grahamii, whereas the isolates from alkaline soils were defined as Ensifer americanum sv. mediterranense and Rhizobium radiobacter. The isolates of "R. leguminosarum" and E. americanum harbored nodC and nifH genes, but the symbiotic genes were not detected in the four isolates of the other two species. It was the first time that "R. leguminosarum" and E. americanum have been reported as bean-nodulating bacteria in Mexico. The high similarity of symbiotic genes in the Rhizobium and Ensifer populations showed that these genes had the same origin and have diversified recently in different rhizobial species. Phenotypic characterization revealed that the "R. leguminosarum" population was more adapted to the acid and low salinity conditions, while the E. americanum population preferred alkaline conditions. The findings of this study have improved the knowledge of the diversity, geographic distribution and evolution of bean-nodulating rhizobia in Mexico.

  20. The fate of nitrogen in a moderately alkaline and calcareous soil amended with biosolids and urea.

    PubMed

    Mendoza, Christina; Assadian, Naomi W; Lindemann, William

    2006-06-01

    The determination of nitrogen (N) based loading rates for land application of biosolids is challenging and site specific. Over loading may contribute to environmental, agricultural, or human health problems. The objective of this study was to monitor N mineralization and losses in a moderately alkaline and calcareous desert soil amended with either anaerobically digested (AN) or lime-stabilized (LS) biosolids, and irrigated with and without urea enriched water. For Experiment 1, N inputs, leaching and residuals in soil were evaluated in an open soil column system. For Experiment 2, ammonia (NH(3)) emissions were evaluated in a closed soil column system. In Experiment 1, AN and LS biosolids increased soil ON (organic N) by three and two fold, respectively. Respective net N mineralization of ON from biosolids alone was 90% and 62% without urea, and 71% and 77%, respectively with added urea. Nitrogen leaching losses and residuals in amended soil did not account for all N inputs into the soil/biosolids system. In Experiment 2, NH(3) emissions were not significantly different among treated soils with or without added urea, except LS amended soil receiving urea. Ammonia losses did not account for unaccounted N in Experiment 1. We concluded that deep placement and rapid mineralization of AN biosolids promoted anaerobic soil conditions and denitrification, in addition to the high denitrification potential of desert soil. LS biosolids showed greater potential than AN biosolids for safe and beneficial land application to desert soils regardless of biosolids placement and the inclusion of N rich irrigation water.

  1. Electrokinetic remediation of fluorine-contaminated soil: conditioning of anolyte.

    PubMed

    Kim, Do-Hyung; Jeon, Chil-Sung; Baek, Kitae; Ko, Sung-Hwan; Yang, Jung-Seok

    2009-01-15

    The feasibility of anolyte conditioning on electrokinetic remediation of fluorine-contaminated soil was investigated with a field soil. The initial concentration of fluorine, pH and water content in the soil were 414mg/kg, 8.91 and 15%, respectively. Because the extraction of fluorine generally increased with the soil pH, the pH of the anode compartment was controlled by circulating strong alkaline solution to enhance the extraction of fluorine during electrokinetic remediation. The removal of fluorine increased with the concentration of the alkaline solution and applied current density and fluorine removed up to 75.6% within 14 days. Additionally, anolyte conditioning sharply increased the electro-osmotic flow, which enhanced the removal of fluorine in this study. In many respects, anolyte conditioning in electrokinetic remediation of fluorine-contaminated soil will be a promising technology.

  2. The Potential of Soft Soil Improvement Through a Coupled Technique Between Electro Kinetic and Alkaline Activation of Soft Soil

    NASA Astrophysics Data System (ADS)

    Ahmed, G. E.; Ismail, H. B.; Huat, B. K.; Afshin, A.; Azhar, A. T. S.

    2016-07-01

    Soil stabilization techniques have been in development for decades with different rates of success. Alkaline activation of soft soil is one of those techniques that has proved to deliver some of the best shear strength values with minor drawbacks in comparison with conventional soil stabilization methods. However, environmental considerations have not been taken into account, as major mineral glassy phase activators are poisoning alkaline solutions, such as sodium-, potassium-hydroxide, and sodium-, potassium-silicate, which poses serious hazards to man and environment. This paper addresses the ways of discarding the involvement of the aforementioned alkaline solutions in soft soil stabilization by investigating the potential of a coupled electro kinetic alkaline activation technique for soft soil strengthening, through which the provision of alkaline pH is governed by electro kinetic potential. Uncertainties in regard to the dissolution of aluminosilicate as well as the dominance of acidic front are challenges that need to be overcome.

  3. Prebiotic synthesis of protobiopolymers under alkaline ocean conditions.

    PubMed

    Ruiz-Bermejo, Marta; Rivas, Luis A; Palacín, Arantxa; Menor-Salván, César; Osuna-Esteban, Susana

    2011-08-01

    Clasically, prebiotic chemistry has focused on the production and identification of simple organic molecules, many of them forming part of "intractable polymers" named tholins. In a previous work, we demonstrated that in experiments using an external energy source and inorganic carbon the aqueous aerosols improved the formation of hydrophilic tholins. Herein, we elucidate the role of pH (from 4 to 12) in prebiotic experiments using saline aqueous aerosols, spark discharges and an atmosphere containing CH(4). At all values of pH, the saline aqueous aerosols increased the production of a significant variety of carboxylic acids that could have been present in a primitive Krebs cycle. Moreover, the study for the first time of hydrophilic tholins by 2-D electrophoresis revealed that these are formed by a set of unexpected heavy polymeric species. The initial alkaline conditions significantly increased both the apparent molecular weight of polymeric species up to 80 kDa and their diversity. We propose the term of protobiopolymers to denote those polymeric species fractionated by 2-D electrophoresis since these are formed by biomolecules present in living systems and show diversity in length as well as in functional groups. Thus, aerosols formed in simulated alkaline ocean conditions could provide an optimal medium for the formation of the primeval materials that could be precursors to the emergence of life.

  4. Prebiotic Synthesis of Protobiopolymers Under Alkaline Ocean Conditions

    NASA Astrophysics Data System (ADS)

    Ruiz-Bermejo, Marta; Rivas, Luis A.; Palacín, Arantxa; Menor-Salván, César; Osuna-Esteban, Susana

    2011-08-01

    Clasically, prebiotic chemistry has focused on the production and identification of simple organic molecules, many of them forming part of "intractable polymers" named tholins. In a previous work, we demonstrated that in experiments using an external energy source and inorganic carbon the aqueous aerosols improved the formation of hydrophilic tholins. Herein, we elucidate the role of pH (from 4 to 12) in prebiotic experiments using saline aqueous aerosols, spark discharges and an atmosphere containing CH4. At all values of pH, the saline aqueous aerosols increased the production of a significant variety of carboxylic acids that could have been present in a primitive Krebs cycle. Moreover, the study for the first time of hydrophilic tholins by 2-D electrophoresis revealed that these are formed by a set of unexpected heavy polymeric species. The initial alkaline conditions significantly increased both the apparent molecular weight of polymeric species up to 80 kDa and their diversity. We propose the term of protobiopolymers to denote those polymeric species fractionated by 2-D electrophoresis since these are formed by biomolecules present in living systems and show diversity in length as well as in functional groups. Thus, aerosols formed in simulated alkaline ocean conditions could provide an optimal medium for the formation of the primeval materials that could be precursors to the emergence of life.

  5. Genetic diversity and community structure of rhizobia nodulating Sesbania cannabina in saline-alkaline soils.

    PubMed

    Li, Yan; Li, Xiangyue; Liu, Yajing; Wang, En Tao; Ren, Chenggang; Liu, Wei; Xu, Hualing; Wu, Hailong; Jiang, Nan; Li, Yunzhao; Zhang, Xiaoli; Xie, Zhihong

    2016-05-01

    Sesbania cannabina is a plant that grows naturally along the seashores in Rudong County, China (RDC) and it has been introduced into the Yellow River Delta (YRD) as a pioneer plant to improve the saline-alkaline soils. In order to investigate the diversity of S. cannabina rhizobia in these soils, a total of 198 rhizobial isolates were characterized and phylogenetic trees were constructed based on data from multilocus sequence analysis (MLSA) of the housekeeping genes recA, atpD and glnII, as well as 16S rRNA. Symbiotic features were also studied by establishing the phylogeny of the symbiotic genes nodA and nifH, and by performing nodulation assays. The isolates had highly conserved symbiotic genes and were classified into nine genospecies belonging to the genera Ensifer, Agrobacterium, Neorhizobium and Rhizobium. A unique community structure was detected in the rhizobia associated with S. cannabina in the saline-alkaline soils that was characterized by five novel genospecies and four defined species. In addition, Ensifer sp. I was the predominant rhizobia in YRD, whereas Ensifer meliloti and Neorhizobium huautlense were the dominant species in RDC. Therefore, the study demonstrated for the first time that this plant strongly selected the symbiotic gene background but not the genomic background of its microsymbionts. In addition, biogeographic patterns existed in the rhizobial populations associated with S. cannabina, which were mainly correlated with pH and salinity, as well as the mineral nutrient contents. This study provided novel information concerning the interaction between soil conditions, host plant and rhizobia, in addition to revealing the diversity of S. cannabina rhizobia in saline-alkaline soils. PMID:27061259

  6. [Impacts of different alkaline soil on canopy spectral characteristics of overlying vegetation].

    PubMed

    Jia, Ke-Li; Zhang, Jun-Hua

    2014-03-01

    The relationship between alkalinity and pH of the soil, reflectance spectra and red-edge parameters of the sunflower canopy in different growth periods under different alkalinity soil were analyzed, respectively. The results showed that the spectral reflectance of the sunflower canopy in different stage under different alkalinity soil is the same as the spectral reflectance characters of the other greenery canopy. Along with the advancement of the sunflower growth period, sunflower canopy spectral reflectance increases gradually at different stages, the spectral reflectance is higher at flowering stage than 7-leaf stage and budding stage, and there exists a high reflection peak at 809nm at flowering period. At the same time, the spectral reflectance is affected by salinity-alkalinity stress at different stages, in the near infrared shortwave band, the spectral reflectance of the sunflower canopy in different stage increases with the decreases in soil alkalinity. When the derivatives are applied to determine the wavelength of the red-edge, there is a shift phenomenon of the red edge. The red edges were at 702-720 nm during every growth period of the sunflower. The "blue shift" phenomenon is also emerged for red edge position and red edge sloped with the increase in the soil alkalinity. Conversely, at the same growth periods, the red edge positions and red edge slope move to longer wave bands with the decrease in soil alkalinity. There is a "red shift" phenomenon before flowering period and "blue shift" phenomenon after flowering period for the red edge position and red edge slope of canopy spectrum at the same soil alkalinity. Respectively. The red edges at different growth stages of the sunflower show very significant positive correlation and quadratic polynomial to alkalinity and pH of the soil. Therefore, we thought used the red edge features of greenery could indicate the soil alkalization degree, it providing scientific basis for monitoring soil alkalization

  7. Activity of soil dehydrogenases, urease, and acid and alkaline phosphatases in soil polluted with petroleum.

    PubMed

    Wyszkowska, Jadwiga; Wyszkowski, Mirosław

    2010-01-01

    This study was undertaken to (1) determine the effects of petroleum pollution on changes in the biochemical properties of soil and (2) demonstrate whether the application of compost, bentonite, and calcium oxide is likely to restore biological balance. Petroleum soil pollution at a dose ranging from 2.5 to 10 cm(3)/kg disturbed the biochemical balance as evidenced by inhibition of the activities of soil dehydrogenases (SDH), urease (URE), and acid phosphatase (ACP). The greatest change was noted in the activity of SDH, whereas the least change occurred in URE. Petroleum significantly increased the activity of soil alkaline phosphatase (ALP) in soil used for spring rape, whereas in soil used for oat harvest there was decreased ALP activity. The application of compost, bentonite, and calcium oxide to soil proved effective in mitigating the adverse effects of petroleum on the activities of soil enzymes. Soil enrichment with compost, bentonite, and calcium oxide was found to stimulate the activities of URE and ALP and inhibit the activity of ACP. The influence of bentonite and calcium oxide was greater than that of compost. Calcium oxide and, to a lesser extent, compost were found to increase the activity of SDH, whereas bentonite exerted the opposite effect, especially in the case of the main crop, spring rape. The activities of SDH, URE, and ACP were higher in soil used for rape than that for oats. In contrast the activity of ALP was higher in soil used for oats. Data thus indicate that compost and especially bentonite and calcium oxide exerted a positive effect on activities of some enzymes in soil polluted with petroleum. Application of neutralizing additives to soil restored soil biological balance by counteracting the negative influence of petroleum on activities of URE and ALP. PMID:20706945

  8. Relationship of catchment topography and soil hydraulic characteristics to lake alkalinity in the northeastern United States

    SciTech Connect

    Wolock, D.M.; Hornberger, G.M.; Beven, K.J.; Campbell, W.G.

    1989-01-01

    The authors undertook the task of determining whether base flow alkalinity of surface waters in the northeastern United States is related to indices of soil contact time and flow path partitioning that are derived from topographic and soils information. The influence of topography and soils on catchment hydrology has been incorporated previously in the variable source area model TOPMODEL as the relative frequency distribution of ln(a/Kb tan B), where ln is the Naperian logarithm, a is the area drained per unit contour, K is the saturated hydraulic conductivity, b is the soil depth, and tan B is the slope. Using digital elevation and soil survey data, the authors calculated the ln (a/Kb tan B) distribution for 145 catchments. Indices of flow path partitioning and soil contact time were derived from the ln(a/Kb tan B) distributions and compared to measurements of alkalinity in lakes to which the catchments drain. They found that alkalinity was, in general, positively correlated with the index of soil contact time, whereas the correlation between alkalinity and the flow path partitioning index was weak at best. A portion of the correlation between the soil contact time index and alkalinity was attributable to covariation with soil base saturation and cation exchange capacity, while another portion was found to be independent of these factors. Although their results indicate that catchments with long soil contact time indices are most likely to produce high alkalinity base flow, a sensitivity analysis of TOPMODEL suggests that surface waters of these same watersheds may be susceptible to alkalinity depressions during storm events, due to the role of flow paths.

  9. Reversible Hydrolysis Reaction with the Spore Photoproduct under Alkaline Conditions.

    PubMed

    Adhikari, Surya; Lin, Gengjie; Li, Lei

    2016-09-16

    DNA lesions may reduce the electron density at the nucleobases, making them prone to further modifications upon the alkaline treatment. The dominant DNA photolesion found in UV-irradiated bacterial endospores is a thymine dimer, 5-thyminyl-5,6-dihydrothymine, i.e., the spore photoproduct (SP). Here we report a stepwise addition/elimination reaction in the SP hydrolysis product under strong basic conditions where a ureido group is added to the carboxyl moiety to form a cyclic amide, regenerating SP after eliminating a hydroxide ion. Direct amidation of carboxylic acids by reaction with amines in the presence of a catalyst is well documented; however, it is very rare for an amidation reaction to occur without activation. This uncatalyzed SP reverse reaction in aqueous solution is even more surprising because the carboxyl moiety is not a good electrophile due to the negative charge it carries. Examination of the base-catalyzed hydrolyses of two other saturated pyrimidine lesions, 5,6-dihydro-2'-deoxyuridine and pyrimidine (6-4) pyrimidone photoproduct, reveals that neither reaction is reversible even though all three hydrolysis reactions may share the same gem-diol intermediate. Therefore, the SP structure where the two thymine residues maintain a stacked conformation likely provides the needed framework enabling this highly unusual carboxyl addition/elimination reaction. PMID:27537985

  10. Microbial population index and community structure in saline-alkaline soil using gene targeted metagenomics.

    PubMed

    Keshri, Jitendra; Mishra, Avinash; Jha, Bhavanath

    2013-03-30

    Population indices of bacteria and archaea were investigated from saline-alkaline soil and a possible microbe-environment pattern was established using gene targeted metagenomics. Clone libraries were constructed using 16S rRNA and functional gene(s) involved in carbon fixation (cbbL), nitrogen fixation (nifH), ammonia oxidation (amoA) and sulfur metabolism (apsA). Molecular phylogeny revealed the dominance of Actinobacteria, Firmicutes and Proteobacteria along with archaeal members of Halobacteraceae. The library consisted of novel bacterial (20%) and archaeal (38%) genera showing ≤95% similarity to previously retrieved sequences. Phylogenetic analysis indicated ability of inhabitant to survive in stress condition. The 16S rRNA gene libraries contained novel gene sequences and were distantly homologous with cultured bacteria. Functional gene libraries were found unique and most of the clones were distantly related to Proteobacteria, while clones of nifH gene library also showed homology with Cyanobacteria and Firmicutes. Quantitative real-time PCR exhibited that bacterial abundance was two orders of magnitude higher than archaeal. The gene(s) quantification indicated the size of the functional guilds harboring relevant key genes. The study provides insights on microbial ecology and different metabolic interactions occurring in saline-alkaline soil, possessing phylogenetically diverse groups of bacteria and archaea, which may be explored further for gene cataloging and metabolic profiling. PMID:23083746

  11. Sorption Behavior of Iodine on Allophane under Acid and Alkaline Conditions - 12203

    SciTech Connect

    Amemiya, Kiyoshi; Nakano, Masashi

    2012-07-01

    In the safety assessment of TRU geological disposal, Iodine-129 (I-129) is considered a key radionuclide. In Japan the reference buffer material within the repository is a bentonite based sand mixture, which is lacking in iodine adsorbent capacity. Additives or alternative buffer materials that can enhance iodine adsorption are desired. Allophane, a common soil material in Japan, is a potential candidate to aid in iodine retention. In order to assess the potential for improvement of buffer and backfill material to limit release of I-129, the sorption behavior of iodine (IO{sub 3}{sup -} and I{sup -}) on allophane was examined in this research. The sorption behavior of IO{sub 3}{sup -} by allophane is strong in acidic conditions, and markedly reduced in alkaline conditions. The K{sub d} values of IO{sub 3}{sup -} are approximately 0.4 m{sup 3}/kg (pH=5), 0.03 m{sup 3}/kg (pH=8), 0.011 m{sup 3}/kg (pH=9), 0.005 m{sup 3}/kg (pH=10). Conversely, the K{sub d} value of I{sup -} is as small as 0.01 m{sup 3}/kg in acidic conditions, and much smaller in alkaline conditions. The numerical analysis shows that a maximum release rate of I-129 from the engineered barrier in the geological disposal system decreased approximately one order of magnitude and the K{sub d} of the buffer increased up to 0.1 m{sup 3}/kg by applying allophane soils to engineered barriers. (authors)

  12. Pseudomonas zhaodongensis sp. nov., isolated from saline and alkaline soils.

    PubMed

    Zhang, Lei; Pan, Yuanyuan; Wang, Kaibiao; Zhang, Xiaoxia; Zhang, Cheng; Zhang, Shuang; Fu, Xiaowei; Jiang, Juquan

    2015-03-01

    Strain NEAU-ST5-21(T) was isolated from saline and alkaline soils in Zhaodong City, Heilongjiang Province, China. It was aerobic, Gram-stain-negative, rod-shaped and motile with a polar flagellum. It produced yellow-orange colonies with a smooth surface, and grew in the presence of 0-5 % (w/v) NaCl (optimum 0 %, w/v), at temperatures of 20-40 °C (optimum 28 °C) and at pH 7-11 (optimum pH 7). Phylogenetic analyses based on the separate 16S rRNA gene sequences and concatenated 16S rRNA, gyrB and rpoD gene sequences indicated that strain NEAU-ST5-21(T) belongs to the genus Pseudomonas in the class Gammaproteobacteria. The most closely related species is Pseudomonas xanthomarina, whose type strain (KMM 1447(T)) showed gene sequence similarities of 99.0 % for 16S rRNA, 81.8 % for gyrB and 85.0 % for rpoD with strain NEAU-ST5-21(T). DNA-DNA hybridization values between strain NEAU-ST5-21(T) and P. xanthomarina DSM 18231(T), Pseudomonas kunmingensis CGMCC 1.12273(T), Pseudomonas stutzeri DSM 5190(T), Pseudomonas oleovorans subsp. lubricantis DSM 21016(T), Pseudomomas chengduensis CGMCC 2318(T), Pseudomonas alcaliphila DSM 17744(T) and Pseudomonas toyotomiensis DSM 26169(T) were 52±0 % to 25±2 %. The DNA G+C content of strain NEAU-ST5-21(T) was 65 mol%. The major fatty acids (>10 %) were C18 : 1ω7c and/or C18 : 1ω6c, C16 : 1ω7c and/or C16 : 1ω6c and C16 : 0, the predominant respiratory quinone was ubiquinone 9, and polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, one unknown phospholipid, phosphatidylglycerol, one unknown aminolipid, one unknown lipid and a glycolipid. The proposed name is Pseudomonas zhaodongensis sp. nov., NEAU-ST5-21(T) ( = ACCC 06362(T) = DSM 27559(T)) being the type strain. PMID:25574037

  13. Lysinibacillus halotolerans sp. nov., isolated from saline-alkaline soil.

    PubMed

    Kong, Delong; Wang, Yanwei; Zhao, Bingqiang; Li, Yanting; Song, Jinlong; Zhai, Yi; Zhang, Chi; Wang, Huimin; Chen, Xiaorong; Zhao, Bin; Ruan, Zhiyong

    2014-08-01

    A novel aerobic, halotolerant bacterium, designated strain LAM612(T), was isolated from saline-alkaline soil samples from Lingxian County, Shandong Province, China. Cells of strain LAM612(T) were Gram-reaction-positive, endospore-forming, motile and rod-shaped. The optimal temperature and pH for growth were 35 °C and pH 6.0, respectively. Strain LAM612(T) could grow in the presence of up to 10% (w/v) NaCl. The genomic DNA G+C conten was 36.4 mol% as detected by the T(m) method. Comparative analysis of 16S rRNA gene sequences revealed that LAM612(T) was closely related to Lysinibacillus sinduriensis KACC 16611(T) (98.0%), L. chungkukjangi KACC 16626(T) (97.5%), L. massiliensis KCTC 13178(T) (97.4%), L. xylanilyticus KACC 15113(T) (97.2%), L. macroides DSM 54(T) (97.0%) and L. manganicus DSM 26584(T) (96.5%). The DNA-DNA hybridization values between strain LAM612(T) and its closest relatives ranged from 20.6% to 41.9%. The major fatty acids of strain LAM612(T) were iso-C(15 : 0) (40.8%), iso-C(16 : 0) (15.2%) and anteiso-C(15 : 0) (10.8%). The cell-wall peptidoglycan content was A4α (L-Lys-D-Asp). The predominant menaquinone was MK-7 and the main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, five unknown glycolipids and an unknown lipid. Based on the DNA-DNA hybridization results and phenotypic, phylogenetic and chemotaxonomic properties, strain LAM612(T) could be distinguished from the recognized species of the genus Lysinibacillus, and was suggested to represent a novel species of this genus, for which the name Lysinibacillus halotolerans sp. nov. is proposed. The type strain is LAM612(T) ( = ACCC 00718(T) = JCM 19611(T)). PMID:24814335

  14. Short-term effect of vermicompost application on biological properties of an alkaline soil with high lime content from Mediterranean region of Turkey.

    PubMed

    Uz, Ilker; Tavali, Ismail Emrah

    2014-01-01

    This study was conducted to investigate direct short-term impact of vermicompost on some soil biological properties by monitoring changes after addition of vermicompost as compared to farmyard manure in an alkaline soil with high lime content from semiarid Mediterranean region of Turkey. For this purpose, mixtures of soil and organic fertilizers in different doses were incubated under greenhouse condition. Soil samples collected in regular intervals were analyzed for biological parameters including dehydrogenase, β-glucosidase, urease, alkaline phosphatase activities, and total number of aerobic mesophilic bacteria. Even though soil dehydrogenase activity appeared to be dose-independent based on overall evaluation, organic amendments were found to elevate dehydrogenase activity when sampling periods are evaluated individually. β-glucosidase, urease, alkaline phosphatase activity, and aerobic mesophilic bacterial numbers in vermicompost treatments fluctuated but remained significantly above the control. A slight but statistically significant difference was detected between organic amendments in terms of urease activity. Vermicompost appeared to more significantly increase bacterial number in soil. Clearly, vermicompost has a potential to be used as an alternative to farmyard manure to improve and maintain soil biological activity in alkaline calcareous soils from the Mediterranean region of Turkey. Further studies are needed to assess its full potential for these soils. PMID:25254238

  15. Short-term effect of vermicompost application on biological properties of an alkaline soil with high lime content from Mediterranean region of Turkey.

    PubMed

    Uz, Ilker; Tavali, Ismail Emrah

    2014-01-01

    This study was conducted to investigate direct short-term impact of vermicompost on some soil biological properties by monitoring changes after addition of vermicompost as compared to farmyard manure in an alkaline soil with high lime content from semiarid Mediterranean region of Turkey. For this purpose, mixtures of soil and organic fertilizers in different doses were incubated under greenhouse condition. Soil samples collected in regular intervals were analyzed for biological parameters including dehydrogenase, β-glucosidase, urease, alkaline phosphatase activities, and total number of aerobic mesophilic bacteria. Even though soil dehydrogenase activity appeared to be dose-independent based on overall evaluation, organic amendments were found to elevate dehydrogenase activity when sampling periods are evaluated individually. β-glucosidase, urease, alkaline phosphatase activity, and aerobic mesophilic bacterial numbers in vermicompost treatments fluctuated but remained significantly above the control. A slight but statistically significant difference was detected between organic amendments in terms of urease activity. Vermicompost appeared to more significantly increase bacterial number in soil. Clearly, vermicompost has a potential to be used as an alternative to farmyard manure to improve and maintain soil biological activity in alkaline calcareous soils from the Mediterranean region of Turkey. Further studies are needed to assess its full potential for these soils.

  16. Short-Term Effect of Vermicompost Application on Biological Properties of an Alkaline Soil with High Lime Content from Mediterranean Region of Turkey

    PubMed Central

    Uz, Ilker; Tavali, Ismail Emrah

    2014-01-01

    This study was conducted to investigate direct short-term impact of vermicompost on some soil biological properties by monitoring changes after addition of vermicompost as compared to farmyard manure in an alkaline soil with high lime content from semiarid Mediterranean region of Turkey. For this purpose, mixtures of soil and organic fertilizers in different doses were incubated under greenhouse condition. Soil samples collected in regular intervals were analyzed for biological parameters including dehydrogenase, β-glucosidase, urease, alkaline phosphatase activities, and total number of aerobic mesophilic bacteria. Even though soil dehydrogenase activity appeared to be dose-independent based on overall evaluation, organic amendments were found to elevate dehydrogenase activity when sampling periods are evaluated individually. β-glucosidase, urease, alkaline phosphatase activity, and aerobic mesophilic bacterial numbers in vermicompost treatments fluctuated but remained significantly above the control. A slight but statistically significant difference was detected between organic amendments in terms of urease activity. Vermicompost appeared to more significantly increase bacterial number in soil. Clearly, vermicompost has a potential to be used as an alternative to farmyard manure to improve and maintain soil biological activity in alkaline calcareous soils from the Mediterranean region of Turkey. Further studies are needed to assess its full potential for these soils. PMID:25254238

  17. [Contrastive analysis on soil alkalinization predicting models based on measured reflectance and TM image reflectance].

    PubMed

    Zhang, Fang; Xiong, Hei-Gang; Long, Tao; Lu, Wen-Juan

    2011-01-01

    Based on the monitored data of soil pH and measured Vis-NIR reflectance on spot in Qitai oasis alkalinized area in Xinjiang, as well as comparison of the relationship between measured reflectance and soil pH and the relationship between TM reflectance and soil pH, both of the reflectance multivariate linear regression models were built to evaluate soil alkalinization level, and the model accuracy of pH fitting was discussed with error inspection of post-sample. The results showed that there is a significant positive correlation between soil pH and reflectance. With pH rising the reflectance increased concurrently. So the alkalinization soil characterized by hardening had good spectral response characteristics. Both measured reflectance and TM image reflectance had good potential ability for change detection of the alkalinization soil. The pH predicting model of measured reflectance had higher accuracy and the major error was from different hardening state. If building model by TM reflectance directly, the accuracy of fitting was lower because of the vegetation information in image spectrum. With the vegetation factor removed with NDVI, the accuracy of TM predicting model was near the accuracy of measured reflectance predicting model, and both of the model levels were good. PMID:21428094

  18. [Contrastive analysis on soil alkalinization predicting models based on measured reflectance and TM image reflectance].

    PubMed

    Zhang, Fang; Xiong, Hei-Gang; Long, Tao; Lu, Wen-Juan

    2011-01-01

    Based on the monitored data of soil pH and measured Vis-NIR reflectance on spot in Qitai oasis alkalinized area in Xinjiang, as well as comparison of the relationship between measured reflectance and soil pH and the relationship between TM reflectance and soil pH, both of the reflectance multivariate linear regression models were built to evaluate soil alkalinization level, and the model accuracy of pH fitting was discussed with error inspection of post-sample. The results showed that there is a significant positive correlation between soil pH and reflectance. With pH rising the reflectance increased concurrently. So the alkalinization soil characterized by hardening had good spectral response characteristics. Both measured reflectance and TM image reflectance had good potential ability for change detection of the alkalinization soil. The pH predicting model of measured reflectance had higher accuracy and the major error was from different hardening state. If building model by TM reflectance directly, the accuracy of fitting was lower because of the vegetation information in image spectrum. With the vegetation factor removed with NDVI, the accuracy of TM predicting model was near the accuracy of measured reflectance predicting model, and both of the model levels were good.

  19. The essential role of coumarin secretion for Fe acquisition from alkaline soil

    PubMed Central

    Clemens, Stephan; Weber, Michael

    2016-01-01

    ABSTRACT Plant productivity is limited by the scarcity of the essential micronutrient iron particularly in alkaline soils. The root secretion of phenolics has long been recognized as a component of the acidification-reduction strategy to acquire iron (strategy I). However, very little molecular insight into this process was available until recently several research groups independently discovered the important role of coumarins for the growth of Arabidopsis thaliana under Fe-limited conditions. Genome-wide analyses of iron deficiency responses, mutant screening and metabolomics experiments all converged on the finding that the synthesis and root exudation of scopoletin, esculetin and other coumarins is essential for iron uptake from substrates with low iron availability. Here we describe the evidence supporting this conclusion and discuss important questions that now have to be addressed in order to better understand the mechanistic basis of coumarin-dependent iron uptake and its significance within the plant kingdom. PMID:26618918

  20. The essential role of coumarin secretion for Fe acquisition from alkaline soil.

    PubMed

    Clemens, Stephan; Weber, Michael

    2016-01-01

    Plant productivity is limited by the scarcity of the essential micronutrient iron particularly in alkaline soils. The root secretion of phenolics has long been recognized as a component of the acidification-reduction strategy to acquire iron (strategy I). However, very little molecular insight into this process was available until recently several research groups independently discovered the important role of coumarins for the growth of Arabidopsis thaliana under Fe-limited conditions. Genome-wide analyses of iron deficiency responses, mutant screening and metabolomics experiments all converged on the finding that the synthesis and root exudation of scopoletin, esculetin and other coumarins is essential for iron uptake from substrates with low iron availability. Here we describe the evidence supporting this conclusion and discuss important questions that now have to be addressed in order to better understand the mechanistic basis of coumarin-dependent iron uptake and its significance within the plant kingdom. PMID:26618918

  1. Increased performance of hydrogen production in microbial electrolysis cells under alkaline conditions.

    PubMed

    Rago, Laura; Baeza, Juan A; Guisasola, Albert

    2016-06-01

    This work reports the first successful enrichment and operation of alkaline bioelectrochemical systems (microbial fuel cells, MFC, and microbial electrolysis cells, MEC). Alkaline (pH=9.3) bioelectrochemical hydrogen production presented better performance (+117%) compared to conventional neutral conditions (2.6 vs 1.2 litres of hydrogen gas per litre of reactor per day, LH2·L(-1)REACTOR·d(-1)). Pyrosequencing results of the anodic biofilm showed that while Geobacter was mainly detected under conventional neutral conditions, Geoalkalibacter sp. was highly detected in the alkaline MFC (21%) and MEC (48%). This is the first report of a high enrichment of Geoalkalibacter from an anaerobic mixed culture using alkaline conditions in an MEC. Moreover, Alkalibacter sp. was highly present in the anodic biofilm of the alkaline MFC (37%), which would indicate its potentiality as a new exoelectrogen.

  2. Increased performance of hydrogen production in microbial electrolysis cells under alkaline conditions.

    PubMed

    Rago, Laura; Baeza, Juan A; Guisasola, Albert

    2016-06-01

    This work reports the first successful enrichment and operation of alkaline bioelectrochemical systems (microbial fuel cells, MFC, and microbial electrolysis cells, MEC). Alkaline (pH=9.3) bioelectrochemical hydrogen production presented better performance (+117%) compared to conventional neutral conditions (2.6 vs 1.2 litres of hydrogen gas per litre of reactor per day, LH2·L(-1)REACTOR·d(-1)). Pyrosequencing results of the anodic biofilm showed that while Geobacter was mainly detected under conventional neutral conditions, Geoalkalibacter sp. was highly detected in the alkaline MFC (21%) and MEC (48%). This is the first report of a high enrichment of Geoalkalibacter from an anaerobic mixed culture using alkaline conditions in an MEC. Moreover, Alkalibacter sp. was highly present in the anodic biofilm of the alkaline MFC (37%), which would indicate its potentiality as a new exoelectrogen. PMID:26855359

  3. Growing season net ecosystem CO2 exchange of two desert ecosystems with alkaline soils in Kazakhstan

    PubMed Central

    Li, Longhui; Chen, Xi; van der Tol, Christiaan; Luo, Geping; Su, Zhongbo

    2014-01-01

    Central Asia is covered by vast desert ecosystems, and the majority of these ecosystems have alkaline soils. Their contribution to global net ecosystem CO2 exchange (NEE) is of significance simply because of their immense spatial extent. Some of the latest research reported considerable abiotic CO2 absorption by alkaline soil, but the rate of CO2 absorption has been questioned by peer communities. To investigate the issue of carbon cycle in Central Asian desert ecosystems with alkaline soils, we have measured the NEE using eddy covariance (EC) method at two alkaline sites during growing season in Kazakhstan. The diurnal course of mean monthly NEE followed a clear sinusoidal pattern during growing season at both sites. Both sites showed significant net carbon uptake during daytime on sunny days with high photosynthetically active radiation (PAR) but net carbon loss at nighttime and on cloudy and rainy days. NEE has strong dependency on PAR and the response of NEE to precipitation resulted in an initial and significant carbon release to the atmosphere, similar to other ecosystems. These findings indicate that biotic processes dominated the carbon processes, and the contribution of abiotic carbon process to net ecosystem CO2 exchange may be trivial in alkaline soil desert ecosystems over Central Asia. PMID:24455157

  4. Utilization of phosphorus loaded alkaline residue to immobilize lead in a shooting range soil.

    PubMed

    Yan, Yubo; Qi, Fangjie; Seshadri, Balaji; Xu, Yilu; Hou, Jiexi; Ok, Yong Sik; Dong, Xiaoli; Li, Qiao; Sun, Xiuyun; Wang, Lianjun; Bolan, Nanthi

    2016-11-01

    The alkaline residue generated from the production of soda ash using the ammonia-soda method has been successfully used in removing phosphorus (P) from aqueous solution. But the accumulation of P-containing solid after P removal is an undesirable menace to the environment. To achieve the goal of recycling, this study explored the feasibility of reusing the P loaded alkaline residue as an amendment for immobilization of lead (Pb) in a shooting range soil. The main crystalline phase and micromorphology of amendments were determined using X-ray diffraction (XRD) and scanning electron microscopy-electron dispersion spectroscopy (SEM-EDS) methods. The toxicity characteristic leaching procedure (TCLP), sequential extraction procedure, and physiologically based extraction test (PBET) were employed to evaluate the effectiveness of Pb immobilization in soil after 45 d incubation. Treatment with P loaded alkaline residue was significantly effective in reducing the TCLP and PBET extractable Pb concentrations in contrast to the untreated soil. Moreover, a positive change in the distribution of Pb fractions was observed in the treated soil, i.e., more than 60% of soil-Pb was transformed to the residual fraction compared to the original soil. On the other hand, P loaded amendments also resulted in a drastic reduction in phytoavailable Pb to the winter wheat and a mild release of P as a nutrient in treated soil, which also confirmed the improvement of soil quality. PMID:27513552

  5. Utilization of phosphorus loaded alkaline residue to immobilize lead in a shooting range soil.

    PubMed

    Yan, Yubo; Qi, Fangjie; Seshadri, Balaji; Xu, Yilu; Hou, Jiexi; Ok, Yong Sik; Dong, Xiaoli; Li, Qiao; Sun, Xiuyun; Wang, Lianjun; Bolan, Nanthi

    2016-11-01

    The alkaline residue generated from the production of soda ash using the ammonia-soda method has been successfully used in removing phosphorus (P) from aqueous solution. But the accumulation of P-containing solid after P removal is an undesirable menace to the environment. To achieve the goal of recycling, this study explored the feasibility of reusing the P loaded alkaline residue as an amendment for immobilization of lead (Pb) in a shooting range soil. The main crystalline phase and micromorphology of amendments were determined using X-ray diffraction (XRD) and scanning electron microscopy-electron dispersion spectroscopy (SEM-EDS) methods. The toxicity characteristic leaching procedure (TCLP), sequential extraction procedure, and physiologically based extraction test (PBET) were employed to evaluate the effectiveness of Pb immobilization in soil after 45 d incubation. Treatment with P loaded alkaline residue was significantly effective in reducing the TCLP and PBET extractable Pb concentrations in contrast to the untreated soil. Moreover, a positive change in the distribution of Pb fractions was observed in the treated soil, i.e., more than 60% of soil-Pb was transformed to the residual fraction compared to the original soil. On the other hand, P loaded amendments also resulted in a drastic reduction in phytoavailable Pb to the winter wheat and a mild release of P as a nutrient in treated soil, which also confirmed the improvement of soil quality.

  6. Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia

    PubMed Central

    Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

    2016-01-01

    Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH)2, nano-MgO, and nano-Zr(OH)4. A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were −583.892 (NaOH), −569.048 [Ca(OH)2], −547.393 (MgO), and −530.279 kJ/mol [Zr(OH)4]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH)2 > MgO > Zr(OH)4. Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH)4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH)4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic. PMID:27785013

  7. Bioremediation of polycyclic aromatic hydrocarbon-contaminated saline-alkaline soils of the former Lake Texcoco.

    PubMed

    Betancur-Galvis, L A; Alvarez-Bernal, D; Ramos-Valdivia, A C; Dendooven, L

    2006-03-01

    Polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene, anthracene and Benzo[a]pyrene (BaP) are toxic for the environment. Removing these components from soil is difficult as they are resistant to degradation and more so in soils with high pH and large salt concentrations as in soil of the former lake Texcoco, but stimulating soil micro-organisms growth by adding nutrients might accelerate soil restoration. Soil of Texcoco and an agricultural Acolman soil, which served as a control, were spiked with phenanthrene, anthracene and BaP, added with or without biosolid or inorganic fertilizer (N, P), and dynamics of PAHs, N and P were monitored in a 112-day incubation. Concentrations of phenanthrene did not change significantly in sterilized Acolman soil, but decreased 2-times in unsterilized soil and >25-times in soil amended with biosolid and NP. The concentration of phenanthrene in unsterilized soil of Texcoco was 1.3-times lower compared to the sterilized soil, 1.7-times in soil amended with NP and 2.9-times in soil amended with biosolid. In unsterilized Acolman soil, degradation of BaP was faster in soil amended with biosolid than in unamended soil and soil amended with NP. In unsterilized soil of Texcoco, degradation of BaP was similar in soil amended with biosolid and NP but faster than in the unamended soil. It was found that application of biosolid and NP increased degradation of phenanthrene, anthracene and BaP, but to a different degree in alkaline-saline soil of Texcoco compared to an agricultural Acolman soil.

  8. Behavior of bensulfuron-methyl in an agricultural alkaline soil.

    PubMed

    Delgado-Moreno, L; Sánchez, L; Castillo, A; Pot, V; Peña, A

    2007-01-01

    A field experiment to determine the available bensulfuron-methyl (BSM) in the upper soil layer was conducted in an agricultural area in the South of Spain. To facilitate herbicide analysis, two application rates were employed, 200 g ha(-1) and 5 kg ha(-1). Samples of upper soil and soil solution were collected. Soil solution was sampled by means of metallic samplers, placed at a depth of 35 cm. In the plots receiving the lower dose ceramic suction, porous cups were also installed. Results from soil solution samples showed that the maximum BSM concentration was found after 8-10 days for the high irrigation supply (945 mm) and after 18-25 days for the lower irrigation regime (405 mm). The mathematical model FOCUSPELMO 1.1.1 was applied to interpret the data obtained in the field experiments. In general, there was a reasonable agreement between experimental and simulated data for soil samples, although the model did not acceptably predict herbicide concentrations in water soil samples. Ceramic cups sampled a higher soil water volume and more frequently than did the metallic samplers. However some variable results were attributed to preferential flow. PMID:17454376

  9. Effects of 10-Year Management Regimes on the Soil Seed Bank in Saline-Alkaline Grassland

    PubMed Central

    Ma, Hongyuan; Yang, Haoyu; Liang, Zhengwei; Ooi, Mark K. J.

    2015-01-01

    Background Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassland management regimes on soil seed bank composition and vegetation establishment in mown, fenced, transplanted and natural grassland sites, all dominated by the perennial rhizomatous grass Leymus chinensis. Methodology We studied species composition and diversity in both the soil seed bank and aboveground vegetation in differently managed grasslands in Northeast China. An NMDS (nonmetric multidimensional scaling) was used to evaluate the relationship between species composition, soil seed banks, aboveground vegetation and soil properties. Principal Findings Fenced and mown grassland sites had high density and species richness in both the soil seed bank and aboveground vegetation. The Transplanted treatment exhibited the highest vegetation growth and seed production of the target species L. chinensis. Seeds of L. chinensis in the soil occurred only in transplanted and natural grassland. Based on the NMDS analysis, the number of species in both the soil seed bank and aboveground vegetation were significantly related to soil Na+, Cl-, RSC (residual sodium carbonate), alkalinity, ESP (exchangeable sodium percentage) and AP (available phosphorus). Conclusions Soil seed bank composition and diversity in the saline-alkaline grassland were significantly affected by the management regimes implemented, and were also significantly related to the aboveground vegetation and several soil properties. Based on vegetative growth, reproductive output and maintenance of soil seed bank, the transplanting was identified as the most effective method for relatively rapid restoration of the target

  10. Uranium(VI) Diffusion in Sodium-Montmorillonite at Alkaline pH Conditions

    NASA Astrophysics Data System (ADS)

    Tinnacher, R. M.; Davis, J. A.; Tournassat, C.; Birkholzer, J. T.

    2015-12-01

    Diffusive transport of uranium(VI) in montmorillonite clay and bentonite has important implications for uranium(VI) mobility in engineered barrier systems or host rocks in high level radioactive waste repositories, and clay-rich soils and sediments in the environment. The prediction of uranium(VI) adsorption and diffusion in clay-rich media, however, is complicated by (1) the complexity of the mineralogical structure of montmorillonite, in terms of its pore-size distributions and available surface site types, and (2) the complex uranium(VI) solution speciation, which can include cationic, uncharged, and anionic complexes, depending on solution conditions. For instance, a partial or full exclusion of anions from negatively charged clay interlayer spaces could change the effective 'anion-accessible' porosity and decrease the diffusive flux of these solutes under steady state conditions. In contrast, weak cation exchange reactions can result in 'surface diffusion' of adsorbed cations, such as UO2OH+, in addition to diffusion in the liquid phase, resulting in greater diffusive fluxes at steady state. In order to investigate these complex interactions, we performed two, lab-scale uranium(VI) through-diffusion experiments in lightly compacted Na-montmorillonite at slightly different, alkaline pH conditions (average pH values of 8.69 and 8.87). Observed uranium(VI) diffusive fluxes were decreased by approximately an order of magnitude in comparison to a tritium tracer. This indicates a relevance of 'anion exclusion' effects, the full or partial exclusion of anionic U(VI)-carbonato species from clay interlayer spaces. In addition, uranium(VI) sorption reactions were shown to be relevant in the diffusion experiments, even at alkaline pH values of around 8.7 and 8.9, where uranium(VI) sorption is low compared to other pH conditions. Despite the similarity of pH conditions, different degrees of uranium(VI) retardation were determined for the two systems. Additionally, we

  11. Clonal Integration Enhances the Performance of a Clonal Plant Species under Soil Alkalinity Stress

    PubMed Central

    Sun, Juanjuan; Chen, Jishan; Zhang, Yingjun

    2015-01-01

    Clonal plants have been shown to successfully survive in stressful environments, including salinity stress, drought and depleted nutrients through clonal integration between original and subsequent ramets. However, relatively little is known about whether clonal integration can enhance the performance of clonal plants under alkalinity stress. We investigated the effect of clonal integration on the performance of a typical rhizomatous clonal plant, Leymus chinensis, using a factorial experimental design with four levels of alkalinity and two levels of rhizome connection treatments, connected (allowing integration) and severed (preventing integration). Clonal integration was estimated by comparing physiological and biomass features between the rhizome-connected and rhizome-severed treatments. We found that rhizome-connected treatment increased the biomass, height and leaf water potential of subsequent ramets at highly alkalinity treatments but did not affect them at low alkalinity treatments. However, rhizome-connected treatment decreased the root biomass of subsequent ramets and did not influence the photosynthetic rates of subsequent ramets. The biomass of original ramets was reduced by rhizome-connected treatment at the highest alkalinity level. These results suggest that clonal integration can increase the performance of clonal plants under alkalinity stress. Rhizome-connected plants showed dramatically increased survival of buds with negative effects on root weight, indicating that clonal integration influenced the resource allocation pattern of clonal plants. A cost-benefit analysis based on biomass measures showed that original and subsequent ramets significantly benefited from clonal integration in highly alkalinity stress, indicating that clonal integration is an important adaptive strategy by which clonal plants could survive in local alkalinity soil. PMID:25790352

  12. Clonal integration enhances the performance of a clonal plant species under soil alkalinity stress.

    PubMed

    Zhang, Wenjun; Yang, Gaowen; Sun, Juanjuan; Chen, Jishan; Zhang, Yingjun

    2015-01-01

    Clonal plants have been shown to successfully survive in stressful environments, including salinity stress, drought and depleted nutrients through clonal integration between original and subsequent ramets. However, relatively little is known about whether clonal integration can enhance the performance of clonal plants under alkalinity stress. We investigated the effect of clonal integration on the performance of a typical rhizomatous clonal plant, Leymus chinensis, using a factorial experimental design with four levels of alkalinity and two levels of rhizome connection treatments, connected (allowing integration) and severed (preventing integration). Clonal integration was estimated by comparing physiological and biomass features between the rhizome-connected and rhizome-severed treatments. We found that rhizome-connected treatment increased the biomass, height and leaf water potential of subsequent ramets at highly alkalinity treatments but did not affect them at low alkalinity treatments. However, rhizome-connected treatment decreased the root biomass of subsequent ramets and did not influence the photosynthetic rates of subsequent ramets. The biomass of original ramets was reduced by rhizome-connected treatment at the highest alkalinity level. These results suggest that clonal integration can increase the performance of clonal plants under alkalinity stress. Rhizome-connected plants showed dramatically increased survival of buds with negative effects on root weight, indicating that clonal integration influenced the resource allocation pattern of clonal plants. A cost-benefit analysis based on biomass measures showed that original and subsequent ramets significantly benefited from clonal integration in highly alkalinity stress, indicating that clonal integration is an important adaptive strategy by which clonal plants could survive in local alkalinity soil. PMID:25790352

  13. Hexavalent uranium diffusion into soils from concentrated acidic and alkaline solutions

    SciTech Connect

    Tokunaga, Tetsu K.; Wan, Jiamin; Pena, Jasquelin; Sutton, Stephen R.; Newville, Matthew

    2004-03-29

    Uranium contamination of soils and sediments often originates from acidic or alkaline waste sources, with diffusion being a major transport mechanism. Measurements of U(VI) diffusion from initially pH 2 and pH 11 solutions into a slightly alkaline Altamont soil and a neutral Oak Ridge soil were obtained through monitoring uptake from boundary reservoirs and from U concentration profiles within soil columns. The soils provided pH buffering, resulting in diffusion at nearly constant pH. Micro x-ray absorption near edge structure spectra confirmed that U remained in U(VI) forms in all soils. Time trends of U(VI) depletion from reservoirs, and U(VI) concentration profiles within soil columns yielded K{sub d} values consistent with those determined in batch tests at similar concentrations ({approx} 1 mM), and much lower than values for sorption at much lower concentrations (nM to {mu}M). These results show that U(VI) transport at high concentrations can be relatively fast at non-neutral pH, with negligible surface diffusion, because of weak sorption.

  14. 24 CFR 3285.201 - Soil conditions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Soil conditions. 3285.201 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Site Preparation § 3285.201 Soil conditions. To help prevent settling or sagging, the foundation must be constructed on firm, undisturbed soil or...

  15. 24 CFR 3285.201 - Soil conditions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Soil conditions. 3285.201 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Site Preparation § 3285.201 Soil conditions. To help prevent settling or sagging, the foundation must be constructed on firm, undisturbed soil or...

  16. 24 CFR 3285.201 - Soil conditions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Soil conditions. 3285.201 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Site Preparation § 3285.201 Soil conditions. To help prevent settling or sagging, the foundation must be constructed on firm, undisturbed soil or...

  17. 24 CFR 3285.201 - Soil conditions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Soil conditions. 3285.201 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Site Preparation § 3285.201 Soil conditions. To help prevent settling or sagging, the foundation must be constructed on firm, undisturbed soil or...

  18. 24 CFR 3285.201 - Soil conditions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Soil conditions. 3285.201 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Site Preparation § 3285.201 Soil conditions. To help prevent settling or sagging, the foundation must be constructed on firm, undisturbed soil or...

  19. Storage/Turnover rate of inorganic carbon and its dissolvable part in the profile of saline/alkaline soils.

    PubMed

    Wang, Yugang; Wang, Zhongyuan; Li, Yan

    2013-01-01

    Soil inorganic carbon is the most common form of carbon in arid and semiarid regions, and has a very long turnover time. However, little is known about dissolved inorganic carbon storage and its turnover time in these soils. With 81 soil samples taken from 6 profiles in the southern Gurbantongute Desert, China, we investigated the soil inorganic carbon (SIC) and the soil dissolved inorganic carbon (SDIC) in whole profiles of saline and alkaline soils by analyzing their contents and ages with radiocarbon dating. The results showed that there is considerable SDIC content in SIC, and the variations of SDIC and SIC contents in the saline soil profile were much larger than that in the alkaline profile. SDIC storage accounted for more than 20% of SIC storage, indicating that more than 1/5 of the inorganic carbon in both saline and alkaline soil is not in non-leachable forms. Deep layer soil contains considerable inorganic carbon, with more than 80% of the soil carbon stored below 1 m, whether for SDIC or SIC. More importantly, SDIC ages were much younger than SIC in both saline soil and alkaline soil. The input rate of SDIC and SIC ranged from 7.58 to 29.54 g C m(-2) yr(-1) and 1.34 to 5.33 g C m(-2) yr(-1) respectively for saline soil, and from 1.43 to 4.9 g C m(-2) yr(-1) and 0.79 to 1.27 g C m(-2) yr(-1)respectively for alkaline soil. The comparison of SDIC and SIC residence time showed that using soil inorganic carbon to estimate soil carbon turnover would obscure an important fraction that contributes to the modern carbon cycle: namely the shorter residence and higher input rate of SDIC. This is especially true for SDIC in deep layers of the soil profile.

  20. Storage/Turnover Rate of Inorganic Carbon and Its Dissolvable Part in the Profile of Saline/Alkaline Soils

    PubMed Central

    Wang, Yugang; Wang, Zhongyuan; Li, Yan

    2013-01-01

    Soil inorganic carbon is the most common form of carbon in arid and semiarid regions, and has a very long turnover time. However, little is known about dissolved inorganic carbon storage and its turnover time in these soils. With 81 soil samples taken from 6 profiles in the southern Gurbantongute Desert, China, we investigated the soil inorganic carbon (SIC) and the soil dissolved inorganic carbon (SDIC) in whole profiles of saline and alkaline soils by analyzing their contents and ages with radiocarbon dating. The results showed that there is considerable SDIC content in SIC, and the variations of SDIC and SIC contents in the saline soil profile were much larger than that in the alkaline profile. SDIC storage accounted for more than 20% of SIC storage, indicating that more than 1/5 of the inorganic carbon in both saline and alkaline soil is not in non-leachable forms. Deep layer soil contains considerable inorganic carbon, with more than 80% of the soil carbon stored below 1 m, whether for SDIC or SIC. More importantly, SDIC ages were much younger than SIC in both saline soil and alkaline soil. The input rate of SDIC and SIC ranged from 7.58 to 29.54 g C m-2 yr-1 and 1.34 to 5.33 g C m-2 yr-1 respectively for saline soil, and from 1.43 to 4.9 g C m-2 yr-1 and 0.79 to 1.27 g C m-2 yr-1respectively for alkaline soil. The comparison of SDIC and SIC residence time showed that using soil inorganic carbon to estimate soil carbon turnover would obscure an important fraction that contributes to the modern carbon cycle: namely the shorter residence and higher input rate of SDIC. This is especially true for SDIC in deep layers of the soil profile. PMID:24312399

  1. Investigation on phase transformation mechanism of zeolite NaY under alkaline hydrothermal conditions

    SciTech Connect

    Li, Peng Ding, Tian Liu, Liping Xiong, Guang

    2013-12-15

    The phase transformation mechanism of zeolite NaY under alkaline hydrothermal conditions was investigated by UV Raman spectroscopy, X-ray diffraction, X-ray fluorescence and scanning electron microscopy techniques. The results revealed that the products and transformation rate are dependent on the alkalinities. All of the starting and resulting zeolites are constructed with the 4-ring and 6-ring secondary building units. The products have lower Si/Al ratio, higher framework density and smaller pore size, which are more stable under alkaline hydrothermal condition. During the phase transformation the fragments of faujasite are formed, then the fragments combine to form different zeolites depending on basicity. Zeolite NaY crystals are consumed as the reservoir for the transformation products during the recrystallization process. For the first time, a 4-membered ring intermediate was found at the early stage of the recrystallization process. A cooperative interaction of liquid and solid phases is required for inducing the phase transformation. - Graphical Abstract: Phase transformation of NaY zeolite under alkaline hydrothermal condition is achieved by the cooperative interaction of the liquid and solid phases. A 4-membered ring species is an intermediate for recrystallization process. Highlights: • The products and transformation rate are dependent on the alkalinity. • A 4-membered ring species is an intermediate for recrystallization process. • A cooperative interaction of liquid and solid phases is required.

  2. Changes in methane oxidation activity and methanotrophic community composition in saline alkaline soils.

    PubMed

    Serrano-Silva, Nancy; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc; Alcántara-Hernández, Rocio J

    2014-05-01

    The soil of the former Lake Texcoco is a saline alkaline environment where anthropogenic drainage in some areas has reduced salt content and pH. Potential methane (CH4) consumption rates were measured in three soils of the former Lake Texcoco with different electrolytic conductivity (EC) and pH, i.e. Tex-S1 a >18 years drained soil (EC 0.7 dS m(-1), pH 8.5), Tex-S2 drained for ~10 years (EC 9.0 dS m(-1), pH 10.3) and the undrained Tex-S3 (EC 84.8 dS m(-1), pH 10.3). An arable soil from Alcholoya (EC 0.7 dS m(-1), pH 6.7), located nearby Lake Texcoco was used as control. Methane oxidation in the soil Tex-S1 (lowest EC and pH) was similar to that in the arable soil from Alcholoya (32.5 and 34.7 mg CH4 kg(-1) dry soil day(-1), respectively). Meanwhile, in soils Tex-S2 and Tex-S3, the potential CH4 oxidation rates were only 15.0 and 12.8 mg CH4 kg(-1) dry soil day(-1), respectively. Differences in CH4 oxidation were also related to changes in the methane-oxidizing communities in these soils. Sequence analysis of pmoA gene showed that soils differed in the identity and number of methanotrophic phylotypes. The Alcholoya soil and Tex-S1 contained phylotypes grouped within the upland soil cluster gamma and the Jasper Ridge, California JR-2 clade. In soil Tex-S3, a phylotype related to Methylomicrobium alcaliphilum was detected. PMID:24638260

  3. Changes in methane oxidation activity and methanotrophic community composition in saline alkaline soils.

    PubMed

    Serrano-Silva, Nancy; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc; Alcántara-Hernández, Rocio J

    2014-05-01

    The soil of the former Lake Texcoco is a saline alkaline environment where anthropogenic drainage in some areas has reduced salt content and pH. Potential methane (CH4) consumption rates were measured in three soils of the former Lake Texcoco with different electrolytic conductivity (EC) and pH, i.e. Tex-S1 a >18 years drained soil (EC 0.7 dS m(-1), pH 8.5), Tex-S2 drained for ~10 years (EC 9.0 dS m(-1), pH 10.3) and the undrained Tex-S3 (EC 84.8 dS m(-1), pH 10.3). An arable soil from Alcholoya (EC 0.7 dS m(-1), pH 6.7), located nearby Lake Texcoco was used as control. Methane oxidation in the soil Tex-S1 (lowest EC and pH) was similar to that in the arable soil from Alcholoya (32.5 and 34.7 mg CH4 kg(-1) dry soil day(-1), respectively). Meanwhile, in soils Tex-S2 and Tex-S3, the potential CH4 oxidation rates were only 15.0 and 12.8 mg CH4 kg(-1) dry soil day(-1), respectively. Differences in CH4 oxidation were also related to changes in the methane-oxidizing communities in these soils. Sequence analysis of pmoA gene showed that soils differed in the identity and number of methanotrophic phylotypes. The Alcholoya soil and Tex-S1 contained phylotypes grouped within the upland soil cluster gamma and the Jasper Ridge, California JR-2 clade. In soil Tex-S3, a phylotype related to Methylomicrobium alcaliphilum was detected.

  4. Characterization of high temperature-tolerant rhizobia isolated from Prosopis juliflora grown in alkaline soil.

    PubMed

    Kulkarni, Suneeta; Nautiyal, Chandra Shekhar

    1999-10-01

    A method was developed for the fast screening and selection of high-temperature tolerant rhizobial strains from root nodules of Prosopis juliflora growing in alkaline soils. The high-temperature tolerant rhizobia were selected from 2,500 Rhizobium isolates with similar growth patterns on yeast mannitol agar plates after 72 h incubation at 30 and 45 degrees C, followed by a second screening at 47.5 degrees C. Seventeen high-temperature tolerant rhizobial strains having distinguishable protein band patterns were finally selected for further screening by subjecting them to temperature stress up to 60 degrees C in yeast mannitol broth for 6 h. The high-temperature tolerant strains were NBRI12, NBRI329, NBRI330, NBRI332, and NBRI133. Using this procedure, a large number of rhizobia from root nodules of P. juliflora were screened for high-temperature tolerance. The assimilation of several carbon sources, tolerance to high pH and salt stress, and ability to nodulate P. juliflora growing in a glasshouse and nursery of the strains were studied. All five isolates had higher plant dry weight in the range of 29.9 to 88.6% in comparison with uninoculated nursery-grown plants. It was demonstrated that it is possible to screen in nature for superior rhizobia exemplified by the isolation of temperature-tolerant strains, which established effective symbiosis with nursery-grown P. juliflora. These findings indicate a correlation between strain performance under in vitro stress in pure culture and strain behavior under symbiotic conditions. Pure culture evaluation may be a useful tool in search for Rhizobium strains better suited for soil environments where high temperature, pH, and salt stress constitutes a limitation for symbiotic biological nitrogen fixation.

  5. Diversity and activity of methanotrophs in alkaline soil from a Chinese coal mine.

    PubMed

    Han, Bing; Chen, Yin; Abell, Guy; Jiang, Hao; Bodrossy, Levente; Zhao, Jiangang; Murrell, J Colin; Xing, Xin-Hui

    2009-11-01

    Culture-independent molecular biological techniques, including 16S rRNA gene and functional gene clone libraries and microarray analyses using pmoA (encoding a key subunit of particulate methane monooxygenase), were applied to investigate the methanotroph community structure in alkaline soil from a Chinese coal mine. This environment contained a high diversity of methanotrophs, including the type II methanotrophs Methylosinus/Methylocystis, type I methanotrophs related to Methylobacter/Methylosoma and Methylococcus, and a number of as yet uncultivated methanotrophs. In order to identify the metabolically active methane-oxidizing bacteria from this alkaline environment, DNA stable isotope probing (DNA-SIP) experiments using (13)CH(4) were carried out. This showed that both type I and type II methanotrophs were active, together with methanotrophs related to Methylocella, which had previously been found only in acidic environments. Methylotrophs, including Methylopila and Hyphomicrobium, were also detected in soil DNA and after DNA-SIP experiments. DNA sequence information on the most abundant, active methanotrophs in this alkaline soil will facilitate the design of oligonucleotide probes to monitor enrichment cultures when isolating key alkaliphilic methanotrophs from such environments. PMID:19515201

  6. EFFECT OF CATIONS ON ALUMINUM SPECIATION UNDER ALKALINE CONDITIONS

    SciTech Connect

    Taylor-Pashow, K.; Hobbs, D.

    2012-07-31

    A series of experiments were performed to examine the effect of metal cations common to high level waste on the phase of aluminum formed. Experiments were performed at temperature of 150 C, 75 C, and room temperature, either without additional metal cation, or with 0.01-0.2 molar equivalents of either Ni{sup 2+}, Fe{sup 3+}, Mn{sup 2+}, or Cr{sup 3+}. Results showed that temperature has the greatest effect on the phase obtained. At 150 C, boehmite is the only phase obtained, independent of the presence of other metal cations, with only one exception where a small amount of gibbsite was also detected in the product when 0.2 equivalents of Ni{sup 2+} was present. At 75 C, a mixture of phases is obtained, most commonly including bayerite and gibbsite; however, boehmite is also formed under some conditions, including in the absence of additional metal ion. At room temperature, in the absence of additional metal ion, a mixture of bayerite and gibbsite is obtained. The addition of another metal cation suppresses the formation of gibbsite, with a couple of exceptions (0.2 equivalents of Ni{sup 2+} or 0.01 equivalents of Cr{sup 3+}) where both phases are still obtained.

  7. Organic Control of Dioctahedral and Trioctahedral Clay Formation in an Alkaline Soil System in the Pantanal Wetland of Nhecolândia, Brazil.

    PubMed

    Barbiero, Laurent; Berger, Gilles; Rezende Filho, Ary T; Meunier, Jean-François; Martins-Silva, Elisângela R; Furian, Sonia

    2016-01-01

    Recent studies have focused on the formation of authigenic clays in an alkaline soil system surrounding lakes of the Nhecolândia region, Pantanal wetland. The presence of trioctahedral Mg-smectites (stevensite and saponite types), which requires low Al and Fe contents in the soil solution for its formation, contrasts with the neoformation of dioctahedral Fe-mica (glauconite, and Fe-illite), which instead requires solutions relatively enriched in Al and Fe. This study aims to understand the conditions of co-existence of both, Mg-smectite and Fe-mica a common clay association in former or modern alkaline soil systems and sediments. The study was carried out along an alkaline soil catena representative of the region. The soil organization revealed that Mg-smectite occur in top soil close to the lake, whereas Fe-mica dominate in the clay fraction of deeper greenish horizons a few meters apart. We propose here that this spatial distribution is controlled by the lateral transfer of Fe and Al with organic ligands. Alkaline organic rich solutions (DOC up to 738 mg L-1) collected in the watertable were centrifuged and filtered through membranes of decreasing pore size (0.45 μm, 0.2 μm, 30 KDa, 10 KDa, 3 KDa) to separate colloidal and dissolved fractions. Fe, Al, Si, Mg and K were analysed for each fraction. Although the filtration had no influence on Si and K contents, almost 90% of Fe (up to 2.3 mg L-1) and Al (up to 7 mg L-1) are retained at the first cutoff threshold of 0.45μm. The treatment of the same solutions by oxygen peroxide before filtration shows that a large proportion of Fe and Al were bonded to organic colloids in alkaline soil solution at the immediate lake border, allowing Mg-smectite precipitation. The fast mineralization of the organic matter a few meters apart from the lake favors the release of Fe and Al necessary for Fe-mica neoformation. In comparison with chemical and mineralogical characteristics of alkaline environments described in the

  8. Organic Control of Dioctahedral and Trioctahedral Clay Formation in an Alkaline Soil System in the Pantanal Wetland of Nhecolândia, Brazil

    PubMed Central

    Meunier, Jean-François; Martins-Silva, Elisângela R.; Furian, Sonia

    2016-01-01

    Recent studies have focused on the formation of authigenic clays in an alkaline soil system surrounding lakes of the Nhecolândia region, Pantanal wetland. The presence of trioctahedral Mg-smectites (stevensite and saponite types), which requires low Al and Fe contents in the soil solution for its formation, contrasts with the neoformation of dioctahedral Fe-mica (glauconite, and Fe-illite), which instead requires solutions relatively enriched in Al and Fe. This study aims to understand the conditions of co-existence of both, Mg-smectite and Fe-mica a common clay association in former or modern alkaline soil systems and sediments. The study was carried out along an alkaline soil catena representative of the region. The soil organization revealed that Mg-smectite occur in top soil close to the lake, whereas Fe-mica dominate in the clay fraction of deeper greenish horizons a few meters apart. We propose here that this spatial distribution is controlled by the lateral transfer of Fe and Al with organic ligands. Alkaline organic rich solutions (DOC up to 738 mg L-1) collected in the watertable were centrifuged and filtered through membranes of decreasing pore size (0.45 μm, 0.2 μm, 30 KDa, 10 KDa, 3 KDa) to separate colloidal and dissolved fractions. Fe, Al, Si, Mg and K were analysed for each fraction. Although the filtration had no influence on Si and K contents, almost 90% of Fe (up to 2.3 mg L-1) and Al (up to 7 mg L-1) are retained at the first cutoff threshold of 0.45μm. The treatment of the same solutions by oxygen peroxide before filtration shows that a large proportion of Fe and Al were bonded to organic colloids in alkaline soil solution at the immediate lake border, allowing Mg-smectite precipitation. The fast mineralization of the organic matter a few meters apart from the lake favors the release of Fe and Al necessary for Fe-mica neoformation. In comparison with chemical and mineralogical characteristics of alkaline environments described in the

  9. Organic Control of Dioctahedral and Trioctahedral Clay Formation in an Alkaline Soil System in the Pantanal Wetland of Nhecolândia, Brazil.

    PubMed

    Barbiero, Laurent; Berger, Gilles; Rezende Filho, Ary T; Meunier, Jean-François; Martins-Silva, Elisângela R; Furian, Sonia

    2016-01-01

    Recent studies have focused on the formation of authigenic clays in an alkaline soil system surrounding lakes of the Nhecolândia region, Pantanal wetland. The presence of trioctahedral Mg-smectites (stevensite and saponite types), which requires low Al and Fe contents in the soil solution for its formation, contrasts with the neoformation of dioctahedral Fe-mica (glauconite, and Fe-illite), which instead requires solutions relatively enriched in Al and Fe. This study aims to understand the conditions of co-existence of both, Mg-smectite and Fe-mica a common clay association in former or modern alkaline soil systems and sediments. The study was carried out along an alkaline soil catena representative of the region. The soil organization revealed that Mg-smectite occur in top soil close to the lake, whereas Fe-mica dominate in the clay fraction of deeper greenish horizons a few meters apart. We propose here that this spatial distribution is controlled by the lateral transfer of Fe and Al with organic ligands. Alkaline organic rich solutions (DOC up to 738 mg L-1) collected in the watertable were centrifuged and filtered through membranes of decreasing pore size (0.45 μm, 0.2 μm, 30 KDa, 10 KDa, 3 KDa) to separate colloidal and dissolved fractions. Fe, Al, Si, Mg and K were analysed for each fraction. Although the filtration had no influence on Si and K contents, almost 90% of Fe (up to 2.3 mg L-1) and Al (up to 7 mg L-1) are retained at the first cutoff threshold of 0.45μm. The treatment of the same solutions by oxygen peroxide before filtration shows that a large proportion of Fe and Al were bonded to organic colloids in alkaline soil solution at the immediate lake border, allowing Mg-smectite precipitation. The fast mineralization of the organic matter a few meters apart from the lake favors the release of Fe and Al necessary for Fe-mica neoformation. In comparison with chemical and mineralogical characteristics of alkaline environments described in the

  10. Soil Properties, Nutrient Dynamics, and Soil Enzyme Activities Associated with Garlic Stalk Decomposition under Various Conditions

    PubMed Central

    Han, Xu; Cheng, Zhihui; Meng, Huanwen

    2012-01-01

    The garlic stalk is a byproduct of garlic production and normally abandoned or burned, both of which cause environmental pollution. It is therefore appropriate to determine the conditions of efficient decomposition, and equally appropriate to determine the impact of this decomposition on soil properties. In this study, the soil properties, enzyme activities and nutrient dynamics associated with the decomposition of garlic stalk at different temperatures, concentrations and durations were investigated. Stalk decomposition significantly increased the values of soil pH and electrical conductivity. In addition, total nitrogen and organic carbon concentration were significantly increased by decomposing stalks at 40°C, with a 5∶100 ratio and for 10 or 60 days. The highest activities of sucrase, urease and alkaline phosphatase in soil were detected when stalk decomposition was performed at the lowest temperature (10°C), highest concentration (5∶100), and shortest duration (10 or 20 days). The evidence presented here suggests that garlic stalk decomposition improves the quality of soil by altering the value of soil pH and electrical conductivity and by changing nutrient dynamics and soil enzyme activity, compared to the soil decomposition without garlic stalks. PMID:23226411

  11. [Effects of mulberry-soybean intercropping on carbon-metabolic microbial diversity in saline-alkaline soil].

    PubMed

    Li, Xin; Zhang, Hui-Hui; Yue, Bing-Bing; Jin, Wei-Wei; Xu, Nan; Zhu, Wen-Xu; Sun, Guang-Yu

    2012-07-01

    Aiming at the characteristics that mulberry-soybean intercropping could alleviate the damage of saline-alkaline soil, Biolog technique was adopted to study the effects of this intercropping on the diversity of carbon-metabolic microbial community in the rhizosphere of saline-alkaline soil. Under mulberry-soybean intercropping, the average well color development (AWCD) symbolizing the metabolic activity of soil microbes was obviously higher, as compared with that under mulberry or soybean monocropping, being the lowest under mulberry monocropping. The McIntosh index was also higher under intercropping than under monocropping, but the Shannon index and Simpson index had less difference between intercropping and monocropping, indicating that intercropping changed the composition and enhanced the diversity of the microbial community in the rhizosphere of saline-alkaline soil. Principal component analysis (PCA) showed that the carbon source utilization mode of the soil microbial community differed between intercropping and monocropping, and the main carbon sources were carbohydrate, carboxylic acid, and polymers. Soil pH and salinity were the main factors limiting the diversity of the microbial community in saline-alkaline soil, and intercropping could effectively decrease the soil pH and salinity and promote the improvement of soil microbial community diversity.

  12. Bioavailability and dissipation of anthracene from soil with different alkalinity and salinity.

    PubMed

    Castro-Silva, Carolina; Ruiz-Valdiviezo, Víctor Manuel; Rivas-Rivera, Sandra Gabriela; Sosa-Trinidad, Alma Rosa; Luna-Guido, Marco; Delgado-Balbuena, Laura; Marsch, Rodolfo; Dendooven, Luc

    2015-01-01

    Bioavailability of contaminants, such as anthracene (Anthra), a polycyclic aromatic hydrocarbon (PAHs), and their removal from soil has been related to their extractability with non-exhaustive techniques, such as hydroxypropyl-beta-cyclodextrin (HPCD) or n-butanol. Anthra was extracted with HPCD, n-butanol and by exhaustive ultrasonic extraction method from sterilized and unsterilized alkaline soil of the former lake Texcoco, having pH ranging from pH 8.2 to 10.1 and electrolytic conductivity varying from 1.2 dS m(-1) to 95.2 dS m(-1), respectively. About 24.4 and 37.6% of Anthra was removed biologically from soil as estimated by exhaustive technique after 56 days. The percentage of Anthra that was removed from soil by exhaustive technique was not related to the amount thatwas extractable with HPCD or n-butanol. It was found that the Anthra extractable with n-butanol or HPCD did not correlate well with the removal of the contaminant from soil. In this study, the removal of Anthra from soil could not be predicted by the amount of Anthra that was extracted with n-butanol or HPCD .

  13. Isolation and identification of myxobacteria from saline-alkaline soils in Xinjiang, China.

    PubMed

    Zhang, Xianjiao; Yao, Qing; Cai, Zhuoping; Xie, Xiaolin; Zhu, Honghui

    2013-01-01

    Fifty-eight terrestrial and salt-tolerant myxobacteria were isolated from the saline-alkaline soils collected from Xinjiang, China. Based on the morphologies and the 16S rRNA gene sequences, these isolates were assigned into 6 genera, Myxococcus, Cystobacter, Corallococcus, Sorangium, Nannocystis and Polyangium. All the strains grew better with 1% NaCl than without NaCl. Some Myxococcus strains were able to grow at 2% NaCl concentration, suggesting that these strains may be particular type of terrestrial myxobacteria. PMID:23936436

  14. America's Soil and Water: Condition and Trends.

    ERIC Educational Resources Information Center

    1981

    A review of conditions and trends regarding soil and water resources of rural nonfederal lands of the United States is presented in this publication. Maps, charts, and graphs illustrate the data collected on various aspects of soil and water use and practice. Topic areas considered include: (1) land use patterns; (2) classes of land; (3)…

  15. Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

    NASA Astrophysics Data System (ADS)

    Luo, W. T.; Nelson, P. N.; Li, M.-H.; Cai, J. P.; Zhang, Y. Y.; Zhang, Y. G.; Yang, S.; Wang, R. Z.; Wang, Z. W.; Wu, Y. N.; Han, X. G.; Jiang, Y.

    2015-12-01

    Soil pH buffering capacity (pHBC) plays a crucial role in predicting acidification rates, yet its large-scale patterns and controls are poorly understood, especially for neutral-alkaline soils. Here, we evaluated the spatial patterns and drivers of pHBC along a 3600 km long transect (1900 km sub-transect with carbonate-containing soils and 1700 km sub-transect with non-carbonate-containing soils) across northern China. Soil pHBC was greater in the carbonate-containing soils than in the non-carbonate-containing soils. Acid addition decreased soil pH in the non-carbonate-containing soils more markedly than in the carbonate-containing soils. Within the carbonate soil sub-transect, soil pHBC was positively correlated with cation exchange capacity (CEC), carbonate content and exchangeable sodium (Na) concentration, but negatively correlated with initial pH and clay content, and not correlated with soil organic carbon (SOC) content. Within the non-carbonate sub-transect, soil pHBC was positively related to initial pH, clay content, CEC and exchangeable Na concentration, but not related to SOC content. Carbonate content was the primary determinant of pHBC in the carbonate-containing soils and CEC was the main determinant of buffering capacity in the non-carbonate-containing soils. Along the transect, soil pHBC was different in regions with different aridity index. Soil pHBC was positively related to aridity index and carbonate content across the carbonate-containing soil sub-transect. Our results indicated that mechanisms controlling pHBC differ among neutral-alkaline soils of northern China, especially between carbonate- and non-carbonate-containing soils. This understanding should be incorporated into the acidification risk assessment and landscape management in a changing world.

  16. Arbuscular mycorrhizal status of wild plants in saline-alkaline soils of the Yellow River Delta.

    PubMed

    Wang, Fa-Yuan; Liu, Run-Jin; Lin, Xian-Gui; Zhou, Jian-Min

    2004-04-01

    A survey was made of the arbuscular mycorrhizal (AM) status of five dominant wild plants Tamarix chinensis, Phragmites communis, Suaeda glauca, Aeluropus littoralis var. sinensis and Cirsium setosum in saline-alkaline soils of the Yellow River Delta that show low plant diversity. All of the species were colonized and showed typical AM structures (arbuscules, vesicles). The colonization percentage ranged from 0.2% to 9.5%, where C. setosum was the highest. The species richness of AMF at the different sites ranged from 2.00 to 2.40 per 50 ml soil, with an average of 2.16. Species diversity ranged from 1.99 to 2.22 per 50 ml soil, with an average of 2.13. Spore density ranged from 3 to 30 per 50 ml soil, with an average of 12. Glomus was the dominant genus, with a frequency and relative abundance of 88.1% and 68.4%, respectively. G. caledonium, with a frequency and relative abundance of 15.0% and 4.6%, respectively, was the dominant species. Differences were also observed in the distribution of AMF in different soil layers. Although there were still AM fungal spores in the layer 40 cm below the surface, most spores were found at a depth of 0-40 cm.

  17. An improved protocol for DNA extraction from alkaline soil and sediment samples for constructing metagenomic libraries.

    PubMed

    Verma, Digvijay; Satyanarayana, T

    2011-09-01

    An improved single-step protocol has been developed for extracting pure community humic substance-free DNA from alkaline soils and sediments. The method is based on direct cell lysis in the presence of powdered activated charcoal and polyvinylpolypyrrolidone followed by precipitation with polyethyleneglycol and isopropanol. The strategy allows simultaneous isolation and purification of DNA while minimizing the loss of DNA with respect to other available protocols for metagenomic DNA extraction. Moreover, the purity levels are significant, which are difficult to attain with any of the methods reported in the literature for DNA extraction from soils. The DNA thus extracted was free from humic substances and, therefore, could be processed for restriction digestion, PCR amplification as well as for the construction of metagenomic libraries. PMID:21519906

  18. Investigation of gelling behavior of thiolated chitosan in alkaline condition and its application in stent coating.

    PubMed

    Zhao, Wei; Kong, Ming; Feng, Chao; Cheng, Xiaojie; Liu, Ya; Chen, Xiguang

    2016-01-20

    The gelling behaviors of thiolated chitosan (TCS) in alkaline condition were investigated. Thioglycolic acid was conjugated onto chitosan backbone through amide bond formation. The variations of thiol group content were monitored in presence of H2O2 or different pH values (pH 7.0, 8.0, 9.0) in dialysis mode. Different from the decreasing thiol group content upon time in acidic condition, increasing amount of thiol groups was detected in alkaline pH during 120 min dialysis attributed to alkaline hydrolysis of intra-molecular disulfide bonds. The extent of which was larger at higher pH values. Higher degree of thiolation, thiomer concentration or pH values promoted gelation of TCS. Entanglement and coagulation of chitosan molecule chains and re-arrangement of disulfide bonds acted closely and dynamically in the gelation process. Disulfide bonds, especially inter-molecular type, are formed by synergetic effects of thiol/disulfide interchange and thiol/thiol oxidation reactions. TCS coated vascular stent displayed wave-like microstructure of parallel ridges and grooves, which favored HUVECs adhesion and proliferation. The biocompatibility, peculiar morphology and thiol moieties of TCS as stent coating material appear application potential for vascular stent. PMID:26572360

  19. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome.

    PubMed

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na(+)). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L(-1) day(-1) organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the "ML635J-40 aquatic group" while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

  20. Facile synthesis of water-soluble carbon nano-onions under alkaline conditions.

    PubMed

    Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García; García, Marta Elena Díaz

    2016-01-01

    Carbonization of tomatoes at 240 °C using 30% (w/v) NaOH as catalyst produced carbon onions (C-onions), while solely carbon dots (C-dots) were obtained at the same temperature in the absence of the catalyst. Other natural materials, such as carrots and tree leaves (acer saccharum), under the same temperature and alkaline conditions did not produce carbon onions. XRD, FTIR, HRTEM, UV-vis spectroscopy, and photoluminescence analyses were performed to characterize the as-synthesized carbon nanomaterials. Preliminary tests demonstrate a capability of the versatile materials for chemical sensing of metal ions. The high content of lycopene in tomatoes may explain the formation of C-onions in alkaline media and a possible formation mechanism for such structures was outlined. PMID:27335764

  1. Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

    PubMed Central

    Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García

    2016-01-01

    Summary Carbonization of tomatoes at 240 °C using 30% (w/v) NaOH as catalyst produced carbon onions (C-onions), while solely carbon dots (C-dots) were obtained at the same temperature in the absence of the catalyst. Other natural materials, such as carrots and tree leaves (acer saccharum), under the same temperature and alkaline conditions did not produce carbon onions. XRD, FTIR, HRTEM, UV–vis spectroscopy, and photoluminescence analyses were performed to characterize the as-synthesized carbon nanomaterials. Preliminary tests demonstrate a capability of the versatile materials for chemical sensing of metal ions. The high content of lycopene in tomatoes may explain the formation of C-onions in alkaline media and a possible formation mechanism for such structures was outlined. PMID:27335764

  2. Changes in the bacterial populations of the highly alkaline saline soil of the former lake Texcoco (Mexico) following flooding.

    PubMed

    Valenzuela-Encinas, César; Neria-González, Isabel; Alcántara-Hernández, Rocio J; Estrada-Alvarado, Isabel; Zavala-Díaz de la Serna, Francisco Javier; Dendooven, Luc; Marsch, Rodolfo

    2009-07-01

    Flooding an extreme alkaline-saline soil decreased alkalinity and salinity, which will change the bacterial populations. Bacterial 16S rDNA libraries were generated of three soils with different electrolytic conductivity (EC), i.e. soil with EC 1.7 dS m(-1) and pH 7.80 (LOW soil), with EC 56 dS m(-1) and pH 10.11 (MEDIUM soil) and with EC 159 dS m(-1) and pH 10.02 (HIGH soil), using universal bacterial oligonucleotide primers, and 463 clone 16S rDNA sequences were analyzed phylogenetically. Library proportions and clone identification of the phyla Proteobacteria, Actinobacteria, Acidobacteria, Cyanobacteria, Bacteroidetes, Firmicutes and Cloroflexi showed that the bacterial communities were different. Species and genera of the Rhizobiales, Rhodobacterales and Xanthomonadales orders of the alpha- and gamma-subdivision of Proteobacteria were found at the three sites. Species and genera of the Rhodospirillales, Sphingobacteriales, Clostridiales, Oscillatoriales and Caldilineales were found only in the HIGH soil, Sphingomonadales, Burkholderiales and Pseudomonadales in the MEDIUM soil, Myxococcales in the LOW soil, and Actinomycetales in the MEDIUM and LOW soils. It was found that the largest diversity at the order and species level was found in the MEDIUM soil as bacteria of both the HIGH and LOW soils were found in it.

  3. [Effects of Festuca arundinacea on the microbial community in crude oil-contaminated saline-alkaline soil].

    PubMed

    Li, Xin; Zhang, Hui-Hui; Yue, Bing-Bing; Xu, Nan; Zhu, Wen-Xu; Hu, Ju-Wei; Sun, Guang-Yu

    2012-12-01

    By using the routine soil physical and chemical analysis methods and the Biolog technique, this paper studied the effects of Festuca arundinacea growth on the pH value, total salt content, and microbial community in the rhizosphere of crude dil-contaminated saline-alkaline soil in Songnen Plain of Northeast China. Crude oil contamination resulted in the increases of average well color development (AWCD), Shannon index (H), and carbon source utilization richness index (S), and altered the utilization patterns of carbon sources by the microbes. F. arundinacea had greater potential to remediate crude oil-contaminated soil. This plant could decrease the soil pH and soil total petroleum hydrocarbon (TPH) content, and increase the soil water content. The AWCD and S in F. arundinacea rhizosphere soil were obviously higher than those in the soil of naked land, providing a suitable environment for the growth and development of rhizosphere soil microbes.

  4. Genotypic alteration and competitive nodulation of Mesorhizobium muleiense against exotic chickpea rhizobia in alkaline soils.

    PubMed

    Zhang, Jun Jie; Yu, Tao; Lou, Kai; Mao, Pei Hong; Wang, En Tao; Chen, Wen Feng; Chen, Wen Xin

    2014-10-01

    Mesorhizobium muleiense, Mesorhizobium mediterraneum and Mesorhizobium ciceri are chickpea (Cicer arietinum L.) rhizobia that share a high similarity of the symbiotic genes nodC and nifH, but they have different geographic distributions. M. muleiense has been isolated and found only in alkaline soils of Xinjiang, China, whereas the other two strains have been found in the Mediterranean and India. To investigate the species stability of M. muleiense during natural evolution and its capability of competitive nodulation against the other two exotic species, re-sampling of nodules in the field and competition experiments between the three species were conducted. The results showed that the predominant microsymbiont associated with chickpea grown in Xinjiang was still M. muleiense, but the predominant genotypes of M. muleiense had changed significantly during the four years since a previous survey. The data also showed that M. mediterraneum and M. ciceri were more competitive than the residential strain of M. muleiense CCBAU 83963(T) in sterilized vermiculite or soils from Xinjiang. However, in non-sterilized soils, M. muleiense was the predominant nodule occupier. These results indicated that natural or adapting evolution of M. muleiense was occurring in fields subjected to changing environmental factors. In addition, the biogeography and symbiotic associations of rhizobia with their host legumes were also influenced by biological factors in the soil, such as indigenous rhizobia and other organisms. PMID:25123757

  5. Testing CO2 Sequestration in an Alkaline Soil Treated with Flue Gas Desulfurization Gypsum (FGDG)

    NASA Astrophysics Data System (ADS)

    Han, Y.; Tokunaga, T. K.

    2012-12-01

    Identifying effective and economical methods for increasing carbon storage in soils is of interest for reducing soil CO2 fluxes to the atmosphere in order to partially offset anthropogenic CO2 contributions to climate change This study investigates an alternative strategy for increasing carbon retention in soils by accelerating calcite (CaCO3) precipitation and promoting soil organic carbon (SOC) complexation on mineral surfaces. The addition of calcium ion to soils with pH > 8, often found in arid and semi-arid regions, may accelerate the slow process of calcite precipitation. Increased ionic strength from addition of a soluble Ca source also suppresses microbial activity which oxidizes SOC to gaseous CO2. Through obtaining C mass balances in soil profiles, this study is quantifying the efficiency of gypsum amendments for mitigating C losses to the atmosphere. The objective of this study is to identify conditions in which inorganic and organic C sequestration is practical in semi-arid and arid soils by gypsum treatment. As an inexpensive calcium source, we proposed to use flue gas desulfurization gypsum (FGDG), a byproduct of fossil fuel burning electric power plants. To test the hypothesis, laboratory column experiments have been conducted in calcite-buffered soil with addition of gypsum and FGDG. The results of several months of column monitoring are demonstrating that gypsum-treated soil have lowered amounts of soil organic carbon loss and increased inorganic carbon (calcite) production. The excess generation of FGDG relative to industrial and agricultural needs, FGDG, is currently regarded as waste. Thus application of FGDG application in some soils may be an effective and economical means for fixing CO2 in soil organic and inorganic carbon forms.Soil carbon cycle, with proposed increased C retention by calcite precipitation and by SOC binding onto soil mineral surfaces, with both processes driven by calcium released from gypsum dissolution.

  6. Exposure to the Proton Scavenger Glycine under Alkaline Conditions Induces Escherichia coli Viability Loss

    PubMed Central

    Vanhauteghem, Donna; Janssens, Geert Paul Jules; Lauwaerts, Angelo; Sys, Stanislas; Boyen, Filip; Cox, Eric; Meyer, Evelyne

    2013-01-01

    Our previous work described a clear loss of Escherichia coli (E. coli) membrane integrity after incubation with glycine or its N-methylated derivatives N-methylglycine (sarcosine) and N,N-dimethylglycine (DMG), but not N,N,N-trimethylglycine (betaine), under alkaline stress conditions. The current study offers a thorough viability analysis, based on a combination of real-time physiological techniques, of E. coli exposed to glycine and its N-methylated derivatives at alkaline pH. Flow cytometry was applied to assess various physiological parameters such as membrane permeability, esterase activity, respiratory activity and membrane potential. ATP and inorganic phosphate concentrations were also determined. Membrane damage was confirmed through the measurement of nucleic acid leakage. Results further showed no loss of esterase or respiratory activity, while an instant and significant decrease in the ATP concentration occurred upon exposure to either glycine, sarcosine or DMG, but not betaine. There was a clear membrane hyperpolarization as well as a significant increase in cellular inorganic phosphate concentration. Based on these results, we suggest that the inability to sustain an adequate level of ATP combined with a decrease in membrane functionality leads to the loss of bacterial viability when exposed to the proton scavengers glycine, sarcosine and DMG at alkaline pH. PMID:23544135

  7. Interactions of Aqueous U(VI) with Soil Minerals in Slightly Alkaline Natural Systems

    SciTech Connect

    Qafoku, Nik; Icenhower, Jonathan P.

    2008-12-01

    Uranium (U) is a common contaminant at numerous surface and subsurface sites around the world. This paper covers some important aspects of the aqueous hexavalent uranium [U(VI)] interactions with soil minerals that are present in contaminated soils and sediments. The retention of U via interactions with soil minerals has significant consequences for the prediction of its short – and long – term behavior in soils and geological systems. Studies of the nature and type of these interactions have provided the necessary evidence for assessing the geochemical behavior of U in natural systems under different physical, biogeochemical, hydrological, and reducing or oxidizing conditions. Over the last 20 years, aqueous U(VI):solid phase interactions have been studied by geochemists, soil chemists, soil mineralogists and soil microbiologists, and the progress in some areas is remarkable. Although a mechanistic description and understanding of the complex interactions involving U and soil minerals of natural systems is currently impossible, results from carefully designed and executed experiments with these materials have improved our understanding of the heterogeneous system’s behavior and U contaminant mobility and transport. There are, however, areas that need further exploration and study. Numerous research publications were reviewed in this paper to present important findings coming out of the research, to reveal the current level of the understanding of the U(VI) interactions with soil minerals, and to provide ideas for future needs and research directions.

  8. The contents of alkali and alkaline earth metals in soils of the southern Cis-Ural region

    NASA Astrophysics Data System (ADS)

    Asylbaev, I. G.; Khabirov, I. K.

    2016-01-01

    The contents and distribution patterns of alkali and alkaline earth metals in soils and rocks of the southern Cis-Ural region were studied. A database on the contents of these metals was developed, the soils were classified with respect to their provision with these metals, and corresponding schematic maps showing their distribution in soils of the region were compiled. It was found that the contents of these metals decrease from east to west (from the Yuryuzan-Aisk Piedmont Plain to the Ufa Plateau and to the Belebeevsk Upland), and their distribution patterns change. Among alkali metals, the highest accumulation in the soils is typical of potassium, sodium, and cesium; among alkaline earth metals, of strontium and barium.

  9. Phenolic Compounds and Their Fates In Tropical Lepidopteran Larvae: Modifications In Alkaline Conditions.

    PubMed

    Vihakas, Matti; Gómez, Isrrael; Karonen, Maarit; Tähtinen, Petri; Sääksjärvi, Ilari; Salminen, Juha-Pekka

    2015-09-01

    Lepidopteran larvae encounter a variety of phenolic compounds while consuming their host plants. Some phenolics may oxidize under alkaline conditions prevailing in the larval guts, and the oxidation products may cause oxidative stress to the larvae. In this study, we aimed to find new ways to predict how phenolic compounds may be modified in the guts of herbivorous larvae. To do so, we studied the ease of oxidation of phenolic compounds from 12 tropical tree species. The leaf extracts were incubated in vitro in alkaline conditions, and the loss of total phenolics during incubation was used to estimate the oxidizability of extracts. The phenolic profiles of the leaf extracts before and after incubation were compared, revealing that some phenolic compounds were depleted during incubation. The leaves of the 12 tree species were each fed to 12 species of lepidopteran larvae that naturally feed on these trees. The phenolic profiles of larval frass were compared to those of in vitro incubated leaf extracts. These comparisons showed that the phenolic profiles of alkali-treated samples and frass samples were similar in many cases. This suggested that certain phenolics, such as ellagitannins, proanthocyanidins, and galloylquinic acid derivatives were modified by the alkaline pH of the larval gut. In other cases, the chromatographic profiles of frass and in vitro incubated leaf extracts were not similar, and new modifications of phenolics were detected in the frass. We conclude that the actual fates of phenolics in vivo are often more complicated than can be predicted by a simple in vitro method. PMID:26364295

  10. Phenolic Compounds and Their Fates In Tropical Lepidopteran Larvae: Modifications In Alkaline Conditions.

    PubMed

    Vihakas, Matti; Gómez, Isrrael; Karonen, Maarit; Tähtinen, Petri; Sääksjärvi, Ilari; Salminen, Juha-Pekka

    2015-09-01

    Lepidopteran larvae encounter a variety of phenolic compounds while consuming their host plants. Some phenolics may oxidize under alkaline conditions prevailing in the larval guts, and the oxidation products may cause oxidative stress to the larvae. In this study, we aimed to find new ways to predict how phenolic compounds may be modified in the guts of herbivorous larvae. To do so, we studied the ease of oxidation of phenolic compounds from 12 tropical tree species. The leaf extracts were incubated in vitro in alkaline conditions, and the loss of total phenolics during incubation was used to estimate the oxidizability of extracts. The phenolic profiles of the leaf extracts before and after incubation were compared, revealing that some phenolic compounds were depleted during incubation. The leaves of the 12 tree species were each fed to 12 species of lepidopteran larvae that naturally feed on these trees. The phenolic profiles of larval frass were compared to those of in vitro incubated leaf extracts. These comparisons showed that the phenolic profiles of alkali-treated samples and frass samples were similar in many cases. This suggested that certain phenolics, such as ellagitannins, proanthocyanidins, and galloylquinic acid derivatives were modified by the alkaline pH of the larval gut. In other cases, the chromatographic profiles of frass and in vitro incubated leaf extracts were not similar, and new modifications of phenolics were detected in the frass. We conclude that the actual fates of phenolics in vivo are often more complicated than can be predicted by a simple in vitro method.

  11. Enhanced decomposition of 1,4-dioxane in water by ozonation under alkaline condition.

    PubMed

    Tian, Gui-Peng; Wu, Qian-Yuan; Li, Ang; Wang, Wen-Long; Hu, Hong-Ying

    2014-01-01

    1,4-Dioxane is a probable human carcinogenic and refractory substance that is widely detected in aquatic environments. Traditional wastewater treatment processes, including activated sludge, cannot remove 1,4-dioxane. Removing 1,4-dioxane with a reaction kinetic constant of 0.32 L/(mol·s) by using ozone, a strong oxidant, is difficult. However, under alkaline environment, ozone generates a hydroxyl radical (•OH) that exhibits strong oxidative potential. Thus, the ozonation of 1,4-dioxane in water under different pH conditions was investigated in this study. In neutral solution, with an inlet ozone feed rate of 0.19 mmol/(L·min), the removal efficiency of 1,4-dioxane was 7.6% at 0.5 h, whereas that in alkaline solution was higher (16.3-94.5%) within a pH range of 9-12. However, the removal efficiency of dissolved organic carbon was considerably lower than that of 1,4-dioxane. This result indicates that several persistent intermediates were generated during 1,4-dioxane ozonation. The pseudo first-order reaction further depicted the reaction of 1,4-dioxane. The obvious kinetic constants (kobs) at pH 9, 10, 11 and 12 were 0.94, 2.41, 24.88 and 2610 L/(mol·s), respectively. Scavenger experiments on radical species indicated that •OH played a key role in removing 1,4-dioxane during ozonation under alkaline condition.

  12. Can hydromorphic conditions accelerate soil development?

    NASA Astrophysics Data System (ADS)

    Ringer, Marianna; Kiss, Klaudia; Horváth-Szabó, Kata; Réka Balázs, Brigitta; Németh, Tibor; Sipos, Péter; Szabó, Máté; Jakab, Gergely; Madarász, Balázs; Szalai, Zoltán

    2016-04-01

    The formation and development of waterlogged (hydromorphic) soils are primarily determined by long-term water saturation. The presence of water in the profile can result increasing speed of soil forming processes including the accumulation of organic matter or other components and mineralogical transformations. Original papers refer more than hundreds of years for this kinds of mineral transformations. We suppose that this process could be more rapid. This study focuses on the mineralogical investigation of a sandy meadow soil (calcic, gleyic Phaeozem ferric, arenic) located in a swampy area in Central Hungary. The starting time of the soil formation is a well documented fact: the parent material deposited during an extremely heavy flood event in the 1960s. Therefore, the studied soil profile is the result of the last half century. Our aim was to explore the degree of mineral phase alteration via soil formation during a half-century under hydromorphic conditions. Routine laboratory measurements (selective dissolution methods for the determination of amorphous and crystalline Fe, and Mn content, X-ray fluorescence spectroscopy measurements for elemental composition determination, X-ray powder diffraction for mineralogical composition, and particle sizing by laser diffraction) were implemented. Morphological and chemical study of carbonate and iron nodules was carried out by electron microprobe. Simple chemical tests (eg. Fe2+ indication by dipiridil test) and morphological observations were performed on the field. Redox potential (Eh) and pH were measured in 20 cm and 40 cm depths by field monitoring station during the vegetation period. Results show that well developed horizons have emerged during fifty years in the studied soil profile. The most intense mineralogical transformations developed in the zone of the heaviest redox oscillation. Soil formation under hydromorphic conditions proceeds at higher speeds contrariwise to the century time scale reported in

  13. Kinetics of the alkaline hydrolysis of 2,4,6-trinitrotoluene in aqueous solution and highly contaminated soils

    SciTech Connect

    Emmrich, M.

    1999-11-01

    During the two World Wars, large amounts of TNT were released into the environment. Until today, high concentrations of TNT can be found in the soil of former ammunition plants. To obtain basic data for a novel treatment process for highly contaminated soils, the homogeneous aqueous hydrolysis of TNT in the pH range from 10 to 12 and the alkaline treatment of two contaminated soils at pH 11 and pH 12 were investigated. The experimental data were described for their respective pH values using a pseudo-first-order model. In the homogeneous experiments, 95--97% of the TNT was hydrolyzed. During alkaline hydrolysis, up to two nitrogroups per TNT molecule were released, indicating the irreversible destruction of TNT. Except for the formation of small traces of amino dinitrotoluenes and trinitrobenzenes, no nitroaromatic benzenes or toluenes were detected during GC analysis. For the less contaminated soil, ELBP2, with an initial TNT concentration of 116 mg/kg, a destruction of 99% was achieved. The highly contaminated soil, HTNT2 (16.1 g of TNT/kg), showed a hydrolyzation level of 90-94%. The results show that the alkaline treatment of highly contaminated soils may prove to be effective as an alternative treatment technology.

  14. Effect of hydrothermal reaction time and alkaline conditions on the electrochemical properties of reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Vermisoglou, E. C.; Giannakopoulou, T.; Romanos, G.; Giannouri, M.; Boukos, N.; Lei, C.; Lekakou, C.; Trapalis, C.

    2015-12-01

    Reduced graphene oxide sheets (rGO) were prepared by hydrothermal treatment of aqueous dispersions of graphite oxide (GtO) applied for short (4 h) and prolonged reaction times (19-24 h). The effect of process duration as well as the alkaline conditions (pH ∼10) by addition of K2CO3 on the quality characteristics of the produced rGO materials was investigated. Both reduction and exfoliation occurred during this process as it was evidenced by FTIR and XRD data. SEM, TEM and HRTEM microscopy displayed highly exfoliated rGO materials. XPS verified that the re-establishment of the conjugated graphene network is more extensive for prolonged times of hydrothermal processing in accordance to Raman spectroscopy measurements. The sample produced under alkaline conditions bore fewer defects and almost 5 times higher BET surface area (∼181 m2/g) than the sample with no pH adjustment (∼34 m2/g) for the same hydrothermal reaction time (19 h), attributed to the developed microporosity. The specific capacitance of this material estimated by electrochemical impedance using three-electrode cell and KCl aqueous solution as an electrolyte was ∼400-500 F/g. When EDLC capacitors were fabricated from rGO materials the electrochemical testing in organic electrolyte i.e. TEABF4 in PC, revealed that the shortest hydrothermal reaction time (4 h) was more efficient resulting in capacitance around 60 F/g.

  15. Microbial reduction of U(VI) under alkaline conditions: implications for radioactive waste geodisposal.

    PubMed

    Williamson, Adam J; Morris, Katherine; Law, Gareth T W; Rizoulis, Athanasios; Charnock, John M; Lloyd, Jonathan R

    2014-11-18

    Although there is consensus that microorganisms significantly influence uranium speciation and mobility in the subsurface under circumneutral conditions, microbiologically mediated U(VI) redox cycling under alkaline conditions relevant to the geological disposal of cementitious intermediate level radioactive waste, remains unexplored. Here, we describe microcosm experiments that investigate the biogeochemical fate of U(VI) at pH 10-10.5, using sediments from a legacy lime working site, stimulated with an added electron donor, and incubated in the presence and absence of added Fe(III) as ferrihydrite. In systems without added Fe(III), partial U(VI) reduction occurred, forming a U(IV)-bearing non-uraninite phase which underwent reoxidation in the presence of air (O2) and to some extent nitrate. By contrast, in the presence of added Fe(III), U(VI) was first removed from solution by sorption to the Fe(III) mineral, followed by bioreduction and (bio)magnetite formation coupled to formation of a complex U(IV)-bearing phase with uraninite present, which also underwent air (O2) and partial nitrate reoxidation. 16S rRNA gene pyrosequencing showed that Gram-positive bacteria affiliated with the Firmicutes and Bacteroidetes dominated in the post-reduction sediments. These data provide the first insights into uranium biogeochemistry at high pH and have significant implications for the long-term fate of uranium in geological disposal in both engineered barrier systems and the alkaline, chemically disturbed geosphere.

  16. Evolution of soil properties and metals in acid and alkaline mine tailing ponds after amendments and microorganisms application

    NASA Astrophysics Data System (ADS)

    Acosta, Jose A.; Faz, Ángel; Zornoza, Raúl; Martínez-Martínez, Silvia; Bech, Jaume

    2015-04-01

    Intense mining activities in the past were carried out in Cartagena-La Unión mining district, SE Spain, and caused excessive accumulation of toxic metals in tailing ponds which poses a high environmental and ecological risk. One of the remediation options gaining considerable interest in recent years is the in situ immobilization of metals. A corresponding reduction in the plant-available metal fraction allows re-vegetation and ecosystem restoration of the heavily contaminated sites. In addition, the use of microorganisms to improve the soil condition is a new tool used to increase spontaneous plant colonization. The aim of this research was to assess the effect of amendments (pig manure, sewage sludge, and lime) and microorganisms on the evolution of soil properties and metals in acid and alkaline tailing ponds and to evaluate the content of metals in Zygophylum fabago one year after amendments application. The study was carried out in two mine ponds (acid and alkaline). Twenty seven square field plots, each one consisting of 4 m2, were located in each pond. Four different doses of microorganism (EM) (0 ml, 20 ml, 100 ml and 200 ml of microorganism solution in each plot) and one dose of pig manure (5 kg per plot), sewage sludge (4 kg per plot) and lime (22 kg per plot) were used. Organic amendment doses were calculated according to European nitrogen legislations, and lime dose was calculated according with the potential acid production through total sulphur oxidation. Three replicates of each treatment (organic amendment + lime + microorganism dose 0, 1, 2, or 3) and control soil (with no amendments) were carried out. Plots were left to the semi-arid climate conditions after the addition of amendments to simulate real potential applications of the results. Soil samples was collected every 4 month from each plot during one year, after this time Zygophylum fabago plants were sampled from each plots. Soil properties including: pH, salinity, total, inorganic and

  17. Black locust--successful invader of a wide range of soil conditions.

    PubMed

    Vítková, Michaela; Tonika, Jaroslav; Müllerová, Jana

    2015-02-01

    Black locust (Robinia pseudoacacia, BL), a species native to North America, has successfully invaded many types of habitats over the world. This study provides an overall assessment of BL soil conditions to determine the range of physical-chemical soil properties it can tolerate. 511 BL stands (for the soil types) and 33 permanent plots (for the soil chemistry) were studied in the Czech Republic. Relationships among different environmental variables (physical-chemical soil properties, vegetation characteristics and habitat conditions) were investigated and variables with the highest effect on species composition were detected. The results were compared with data in the literature for other parts of the secondary and native distributions of this species. This assessment showed that BL is able to tolerate extremely diverse soil physical-chemical conditions, from extremely acid to strongly alkaline, and from medium to highly base saturated soils with a gradient of different subsurface stoniness. Soil nitrate, N mineralization and nitrification rates also varied considerably and the concentrations of exchangeable phosphorus and ammonium were consistently low. N mineralization rate, incubated inorganic nitrogen and nitrates were positively correlated with base saturation and cation exchange capacity. The most common soil types were young soils (Cambisols, Leptosols, Arenosols, and coarsely textured Fluvisols). BL seems to be limited by water supply and soil aeration and prefers well aerated and drained soils, and tolerates desiccation but avoids compact soils and areas where the soils are frequently waterlogged. On steep slopes, BL was less vigorous, stunted and less competitive. By contrast, the tallest BL trees were found on sandy soils in a flat landscape. Number and share of nitrophytes in the herb layer were positively related to basic bedrock, soil reaction and N-NO3/N ratio. Soil reaction was determined as the most important environmental characteristic

  18. M4FT-15OR03100421: Status Report on Alkaline Conditioning Studies

    SciTech Connect

    Tsouris, Costas; Brown, Suree; Janke, Christopher James; Mayes, Richard T.; Dai, Sheng; Kuo, Li-Jung; Gill, Gary

    2015-05-01

    Significant progress in understanding the role of alkaline conditioning of polyethylene-fiber adsorbent, developed at the Oak Ridge National Laboratory (ORNL), is demonstrated in this report, which is essentially a manuscript prepared for publication in the journal Industrial & Engineering Chemistry Research of the American Chemical Society. The manuscript describes the influence of various parameters involved in adsorbent alkaline conditioning, including base concentration and duration and temperature of conditioning, on the uranium uptake history by the adsorbent. Various solutions have been used to determine the influence of conditioning parameters including (i) a screening solution containing uranyl nitrate at approximately 8 ppm and sodium bicarbonate and sodium chloride at concentrations similar to those found in seawater, (ii) seawater spiked with approximately 75 ppb uranium, and (iii) natural seawater. In addition to concentration measurements by inductively coupled plasma (ICP) spectroscopy to determine the uranium uptake capacity and kinetics, spectroscopic methods such as Fourier transformed infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy were employed to investigate the effect of base treatment on the various chemical bonds of the adsorbent. Scanning electron microscopy (SEM) has also been employed to determine structural effects of the alkali on the adsorbent. The results are summarized as follows: 1. Alkali conditioning is necessary to prepare the adsorbent for uranium uptake. ICP analysis showed that without alkali conditioning, no appreciable uranium adsorption occurs. 2. FTIR showed that the base converts amidoxime to carboxylate groups. 3. FTIR showed that formation of carboxylate groups is irreversible and reduces the selectivity of the adsorbent toward uranium. 4. NMR showed that alkali conditioning leads also to the formation of cyclic imidedioxime, which is suspected to bind uranium, vanadium, iron, copper, and

  19. Biological sulfide removal under alkaline and aerobic conditions in a packed recycling reactor.

    PubMed

    González-Sánchez, A; Revah, S

    2009-01-01

    The biological sulfide removal from wastewater caustic streams can be achieved without significant dilution by alkaliphilic microorganisms which usually show lower growth and oxidation rates as compared with acidic and neutral bacteria. To improve volumetric removal rates under alkaline condition (pH 10), an Alkaliphilic Sulfide-oxidizing Bacteria Consortium (ASBC) was studied in a Packed Recycling Reactor (PRR). A commercial Nylon fiber resulted to be a convenient packing support for biofilm development as it has high specific area and similar hydrophobic propertie. The PRR reached a maximum sulfide oxidation rate of 100 mmol L(-1) d(-1) with efficiency close to 100%, representing an enhancement of 56% from the maximum sulfide oxidation rate reached for a free cell continuous culture. Higher sulfide loading rates induced oxygen limiting conditions reducing the biological activity despite the considerable biofilm attached on the nylon fiber.

  20. Biological sulfide removal under alkaline and aerobic conditions in a packed recycling reactor.

    PubMed

    González-Sánchez, A; Revah, S

    2009-01-01

    The biological sulfide removal from wastewater caustic streams can be achieved without significant dilution by alkaliphilic microorganisms which usually show lower growth and oxidation rates as compared with acidic and neutral bacteria. To improve volumetric removal rates under alkaline condition (pH 10), an Alkaliphilic Sulfide-oxidizing Bacteria Consortium (ASBC) was studied in a Packed Recycling Reactor (PRR). A commercial Nylon fiber resulted to be a convenient packing support for biofilm development as it has high specific area and similar hydrophobic propertie. The PRR reached a maximum sulfide oxidation rate of 100 mmol L(-1) d(-1) with efficiency close to 100%, representing an enhancement of 56% from the maximum sulfide oxidation rate reached for a free cell continuous culture. Higher sulfide loading rates induced oxygen limiting conditions reducing the biological activity despite the considerable biofilm attached on the nylon fiber. PMID:19381008

  1. Fate of Zinc Oxide Nanoparticles Coated onto Macronutrient Fertilizers in an Alkaline Calcareous Soil.

    PubMed

    Milani, Narges; Hettiarachchi, Ganga M; Kirby, Jason K; Beak, Douglas G; Stacey, Samuel P; McLaughlin, Mike J

    2015-01-01

    Zinc oxide (ZnO) nanoparticles may provide a more soluble and plant available source of Zn in Zn fertilizers due to their greater reactivity compared to equivalent micron- or millimetre-sized (bulk) particles. However, the effect of soil on solubility, spatial distribution and speciation of ZnO nanoparticles has not yet been investigated. In this study, we examined the diffusion and solid phase speciation of Zn in an alkaline calcareous soil following application of nanoparticulate and bulk ZnO coated fertilizer products (monoammonium phosphate (MAP) and urea) using laboratory-based x-ray techniques and synchrotron-based μ-x-ray fluorescence (μ-XRF) mapping and absorption fine structure spectroscopy (μ-XAFS). Mapping of the soil-fertilizer reaction zones revealed that most of the applied Zn for all treatments remained on the coated fertilizer granule or close to the point of application after five weeks of incubation in soil. Zinc precipitated mainly as scholzite (CaZn2(PO4)2.2H2O) and zinc ammonium phosphate (Zn(NH4)PO4) species at the surface of MAP granules. These reactions reduced dissolution and diffusion of Zn from the MAP granules. Although Zn remained as zincite (ZnO) at the surface of urea granules, limited diffusion of Zn from ZnO-coated urea granules was also observed for both bulk and nanoparticulate ZnO treatments. This might be due to either the high pH of urea granules, which reduced solubility of Zn, or aggregation (due to high ionic strength) of released ZnO nanoparticles around the granule/point of application. The relative proportion of Zn(OH)2 and ZnCO3 species increased for all Zn treatments with increasing distance from coated MAP and urea granules in the calcareous soil. When coated on macronutrient fertilizers, Zn from ZnO nanoparticles (without surface modifiers) was not more mobile or diffusible compared to bulk forms of ZnO. The results also suggest that risk associated with the presence of ZnO NPs in calcareous soils would be the same

  2. Fate of Zinc Oxide Nanoparticles Coated onto Macronutrient Fertilizers in an Alkaline Calcareous Soil.

    PubMed

    Milani, Narges; Hettiarachchi, Ganga M; Kirby, Jason K; Beak, Douglas G; Stacey, Samuel P; McLaughlin, Mike J

    2015-01-01

    Zinc oxide (ZnO) nanoparticles may provide a more soluble and plant available source of Zn in Zn fertilizers due to their greater reactivity compared to equivalent micron- or millimetre-sized (bulk) particles. However, the effect of soil on solubility, spatial distribution and speciation of ZnO nanoparticles has not yet been investigated. In this study, we examined the diffusion and solid phase speciation of Zn in an alkaline calcareous soil following application of nanoparticulate and bulk ZnO coated fertilizer products (monoammonium phosphate (MAP) and urea) using laboratory-based x-ray techniques and synchrotron-based μ-x-ray fluorescence (μ-XRF) mapping and absorption fine structure spectroscopy (μ-XAFS). Mapping of the soil-fertilizer reaction zones revealed that most of the applied Zn for all treatments remained on the coated fertilizer granule or close to the point of application after five weeks of incubation in soil. Zinc precipitated mainly as scholzite (CaZn2(PO4)2.2H2O) and zinc ammonium phosphate (Zn(NH4)PO4) species at the surface of MAP granules. These reactions reduced dissolution and diffusion of Zn from the MAP granules. Although Zn remained as zincite (ZnO) at the surface of urea granules, limited diffusion of Zn from ZnO-coated urea granules was also observed for both bulk and nanoparticulate ZnO treatments. This might be due to either the high pH of urea granules, which reduced solubility of Zn, or aggregation (due to high ionic strength) of released ZnO nanoparticles around the granule/point of application. The relative proportion of Zn(OH)2 and ZnCO3 species increased for all Zn treatments with increasing distance from coated MAP and urea granules in the calcareous soil. When coated on macronutrient fertilizers, Zn from ZnO nanoparticles (without surface modifiers) was not more mobile or diffusible compared to bulk forms of ZnO. The results also suggest that risk associated with the presence of ZnO NPs in calcareous soils would be the same

  3. Fate of Zinc Oxide Nanoparticles Coated onto Macronutrient Fertilizers in an Alkaline Calcareous Soil

    PubMed Central

    Milani, Narges; Hettiarachchi, Ganga M.; Kirby, Jason K.; Beak, Douglas G.; Stacey, Samuel P.; McLaughlin, Mike J.

    2015-01-01

    Zinc oxide (ZnO) nanoparticles may provide a more soluble and plant available source of Zn in Zn fertilizers due to their greater reactivity compared to equivalent micron- or millimetre-sized (bulk) particles. However, the effect of soil on solubility, spatial distribution and speciation of ZnO nanoparticles has not yet been investigated. In this study, we examined the diffusion and solid phase speciation of Zn in an alkaline calcareous soil following application of nanoparticulate and bulk ZnO coated fertilizer products (monoammonium phosphate (MAP) and urea) using laboratory-based x-ray techniques and synchrotron-based μ-x-ray fluorescence (μ–XRF) mapping and absorption fine structure spectroscopy (μ–XAFS). Mapping of the soil-fertilizer reaction zones revealed that most of the applied Zn for all treatments remained on the coated fertilizer granule or close to the point of application after five weeks of incubation in soil. Zinc precipitated mainly as scholzite (CaZn2(PO4)2.2H2O) and zinc ammonium phosphate (Zn(NH4)PO4) species at the surface of MAP granules. These reactions reduced dissolution and diffusion of Zn from the MAP granules. Although Zn remained as zincite (ZnO) at the surface of urea granules, limited diffusion of Zn from ZnO-coated urea granules was also observed for both bulk and nanoparticulate ZnO treatments. This might be due to either the high pH of urea granules, which reduced solubility of Zn, or aggregation (due to high ionic strength) of released ZnO nanoparticles around the granule/point of application. The relative proportion of Zn(OH)2 and ZnCO3 species increased for all Zn treatments with increasing distance from coated MAP and urea granules in the calcareous soil. When coated on macronutrient fertilizers, Zn from ZnO nanoparticles (without surface modifiers) was not more mobile or diffusible compared to bulk forms of ZnO. The results also suggest that risk associated with the presence of ZnO NPs in calcareous soils would be the

  4. Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease.

    PubMed

    Cui, Hongxia; Yang, Muyang; Wang, Liping; Xian, Cory J

    2015-01-01

    While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated. Strain SD8 was initially classified to belong to genus Pseudomonas by morphological, physiological and biochemical characterizations, and then through 16S rDNA sequence it was identified to be likely Pseudomonas hibiscicola. In addition, the culture mediums, carbon sources and culture conditions of strain SD8 were optimized for maximum production of alkaline protease. Optimum enzyme production (236U/mL when cultured bacteria being at 0.75 mg dry weight/mL fermentation broth) was obtained when the isolate at a 3% inoculum size was grown in LB medium at 20 mL medium/100mL Erlenmeyer flask for 48h culture at 30°C with an initial of pH 7.5. This was the first report of strain Pseudomonas hibiscicola secreting alkaline protease, and the data for its optimal cultural conditions for alkaline protease production has laid a foundation for future exploration for the potential use of SD8 strain for alkaline protease production.

  5. Sporosarcina pasteurii use in extreme alkaline conditions for recycling solid industrial wastes.

    PubMed

    Cuzman, Oana A; Rescic, Silvia; Richter, Katharina; Wittig, Linda; Tiano, Piero

    2015-11-20

    The ureolytic bacteria are one of the most efficient organisms able to produce high amounts of carbonate that easily react with the free calcium ions from the environment. Sporosarcina pasteurii, a robust microbe in alkaline environments, was tested in this work for its potential use in an eco-cementation process that involves the biomediated calcite precipitation (BCP). Bacterial behavior in extreme alkaline environment (pH values of 9-13) was tested in controlled laboratory conditions and in the presence of solid industry wastes, such as Cement Kiln Dust (CKD) and Lime Kiln Dust (LKD), by evaluating the enzymatic activity and the calcite precipitation capacity. Grain consolidation potential of S. pasteurii was tested for one type of CKD mixed with ground granulated blast-furnace slag (GGBS), with possible bioclogging and biocementation applications. The results revealed the formation of stable biocalcite in the presence of CKD, with a performance depending on the pH-value and free calcium ion content. The BCP induced by S. pasteurii and the recycling of solid wastes, such as CKD with high lime content, is a promising way for different bioclogging and biocementation applications, with benefits in construction costs and reduction of environmental pollution. PMID:26376469

  6. Use of highly alkaline conditions to improve cost-effectiveness of algal biotechnology.

    PubMed

    Canon-Rubio, Karen A; Sharp, Christine E; Bergerson, Joule; Strous, Marc; De la Hoz Siegler, Hector

    2016-02-01

    Phototrophic microorganisms have been proposed as an alternative to capture carbon dioxide (CO2) and to produce biofuels and other valuable products. Low CO2 absorption rates, low volumetric productivities, and inefficient downstream processing, however, currently make algal biotechnology highly energy intensive, expensive, and not economically competitive to produce biofuels. This mini-review summarizes advances made regarding the cultivation of phototrophic microorganisms at highly alkaline conditions, as well as other innovations oriented toward reducing the energy input into the cultivation and processing stages. An evaluation, in terms of energy requirements and energy return on energy invested, is performed for an integrated high-pH, high-alkalinity growth process that uses biofilms. Performance in terms of productivity and expected energy return on energy invested is presented for this process and is compared to previously reported life cycle assessments (LCAs) for systems at near-neutral pH. The cultivation of alkaliphilic phototrophic microorganisms in biofilms is shown to have a significant potential to reduce both energy requirements and capital costs.

  7. Bacterial degradation of cyanide and its metal complexes under alkaline conditions.

    PubMed

    Luque-Almagro, Víctor M; Huertas, María-J; Martínez-Luque, Manuel; Moreno-Vivián, Conrado; Roldán, M Dolores; García-Gil, L Jesús; Castillo, Francisco; Blasco, Rafael

    2005-02-01

    A bacterial strain able to use cyanide as the sole nitrogen source under alkaline conditions has been isolated. The bacterium was classified as Pseudomonas pseudoalcaligenes by comparison of its 16S RNA gene sequence to those of existing strains and deposited in the Coleccion Espanola de Cultivos Tipo (Spanish Type Culture Collection) as strain CECT5344. Cyanide consumption is an assimilative process, since (i) bacterial growth was concomitant and proportional to cyanide degradation and (ii) the bacterium stoichiometrically converted cyanide into ammonium in the presence of l-methionine-d,l-sulfoximine, a glutamine synthetase inhibitor. The bacterium was able to grow in alkaline media, up to an initial pH of 11.5, and tolerated free cyanide in concentrations of up to 30 mM, which makes it a good candidate for the biological treatment of cyanide-contaminated residues. Both acetate and d,l-malate were suitable carbon sources for cyanotrophic growth, but no growth was detected in media with cyanide as the sole carbon source. In addition to cyanide, P. pseudoalcaligenes CECT5344 used other nitrogen sources, namely ammonium, nitrate, cyanate, cyanoacetamide, nitroferricyanide (nitroprusside), and a variety of cyanide-metal complexes. Cyanide and ammonium were assimilated simultaneously, whereas cyanide strongly inhibited nitrate and nitrite assimilation. Cyanase activity was induced during growth with cyanide or cyanate, but not with ammonium or nitrate as the nitrogen source. This result suggests that cyanate could be an intermediate in the cyanide degradation pathway, but alternative routes cannot be excluded.

  8. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome

    PubMed Central

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E.

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na+). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L−1 day−1 organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the “ML635J-40 aquatic group” while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

  9. Anditalea andensis ANESC-ST--An Alkaliphilic Halotolerant Bacterium Capable of Electricity Generation under Alkaline-Saline Conditions.

    PubMed

    Shi, Wei; Wang, Victor Bochuan; Zhao, Cui-E; Zhang, Qichun; Loo, Say Chye Joachim; Yang, Liang; Xu, Chenjie

    2015-01-01

    A great challenge in wastewater bioremediation is the sustained activity of viable microorganisms, which can contribute to the breakdown of waste contaminants, especially in alkaline pH conditions. Identification of extremophiles with bioremediation capability can improve the efficiency of wastewater treatment. Here, we report the discovery of an electrochemically active alkaliphilic halotolerant bacterium, Anditalea andensis ANESC-ST (=CICC10485T=NCCB 100412T), which is capable of generating bioelectricity in alkaline-saline conditions. A. andensis ANESC-ST was shown to grow in alkaline conditions between pH 7.0-11.0 and also under high salt condition (up to 4 wt% NaCl). Electrical output was further demonstrated in microbial fuel cells (MFCs) with an average current density of ~0.5 µA/cm2, even under the harsh condition of 4 wt% NaCl and pH 9.0. Subsequent introduction of secreted extracellular metabolites into MFCs inoculated with Escherichia coli or Pseudomonas aeruginosa yielded enhanced electrical output. The ability of A. andensis ANESC-ST to generate energy under alkaline-saline conditions points towards a solution for bioelectricity recovery from alkaline-saline wastewater. This is the first report of A.andensis ANESC-ST producing bioelectricity at high salt concentration and pH.

  10. New pathways for the rapid formation of N-nitrosamines under neutral and alkaline conditions.

    PubMed

    Challis, B C; Outram, J R; Shuker, D E

    1980-01-01

    Ethylene glycol, several carbohydrates (sugars) and alkanolamines influence the formation of carcinogenic N-nitrosamines in neutral and alkaline aqueous solutions at 25 degrees C in presence of dissolved nitrosyl gases. These compounds either catalyse or inhibit the reactions (depending on the experimental conditions and reagent reactivities) by forming a nitrite ester intermediate, which reacts readily with secondary amines. The reactions may explain the origin of some N-nitrosamines in vivo and in consumer products, particularly those originating from NOX pollutants. N-Nitrosamines are also formed at ambient temperatures by the gamma-radiolysis of neutral aqueous solutions of either NaNO2 or NaNO3 and secondary amines. With NaNO3, N-nitroamines are in accompanying product. These reactions are considered to proceed via N2O3 and N2O4 intermediates, generated from NaNO2 and NaNO3, respectively.

  11. Arsenopyrite weathering under conditions of simulated calcareous soil.

    PubMed

    Lara, René H; Velázquez, Leticia J; Vazquez-Arenas, Jorge; Mallet, Martine; Dossot, Manuel; Labastida, Israel; Sosa-Rodríguez, Fabiola S; Espinosa-Cristóbal, León F; Escobedo-Bretado, Miguel A; Cruz, Roel

    2016-02-01

    Mining activities release arsenopyrite into calcareous soils where it undergoes weathering generating toxic compounds. The research evaluates the environmental impacts of these processes under semi-alkaline carbonated conditions. Electrochemical (cyclic voltammetry, chronoamperometry, EIS), spectroscopic (Raman, XPS), and microscopic (SEM, AFM, TEM) techniques are combined along with chemical analyses of leachates collected from simulated arsenopyrite weathering to comprehensively examine the interfacial mechanisms. Early oxidation stages enhance mineral reactivity through the formation of surface sulfur phases (e.g., S n (2-)/S(0)) with semiconductor properties, leading to oscillatory mineral reactivity. Subsequent steps entail the generation of intermediate siderite (FeCO3)-like, followed by the formation of low-compact mass sub-micro ferric oxyhydroxides (α, γ-FeOOH) with adsorbed arsenic (mainly As(III), and lower amounts of As(V)). In addition, weathering reactions can be influenced by accessible arsenic resulting in the formation of a symplesite (Fe3(AsO4)3)-like compound which is dependent on the amount of accessible arsenic in the system. It is proposed that arsenic release occurs via diffusion across secondary α, γ-FeOOH structures during arsenopyrite weathering. We suggest weathering mechanisms of arsenopyrite in calcareous soil and environmental implications based on experimental data.

  12. [Effects and mechanism of alkaline wastes application and zinc fertilizer addition on Cd bioavailability in contaminated soil].

    PubMed

    Liu, Zhao-Bing; Ji, Xiong-Hui; Tian, Fa-Xiang; Peng, Hua; Wu, Jia-Mei; Shi, Li-Hong

    2011-04-01

    The effects of paper mill sludge, red mud and zinc fertilizer addition on remediation of acid cadmium contaminated paddy soil were studied in a pot experiment, and their beneficial effects were verified in a field experiment, by using lime as comparison. The pot experiment results showed that a single application (2 g x kg(-1)) of lime, paper mill sludge or red mud increased soil pH significantly. Compared with no applying alkaline substances, the soil exchangeable Ca content was increased by 33.1%-76.0% at 7 days after applying alkaline substances and 31.0%-78.3% at 30 days after rice transplanting, respectively. The soil available Cd content was significantly decreased by 38.4%-45.0% at 7 days after the three alkaline substances applications, and was decreased by 37.4%-52.9% and 33.2%-38.7% at 30 days and 60 days after rice transplanting, respectively. The Cd content in rice root and brown rice was decreased by 24.0%-48.5% and 26.3%-44.7%, respectively. With equal applications of lime, paper mill sludge and red mud, the effects on increase of soil pH and decrease in Cd accumulation by rice was lime > red mud > paper mill sludge. Compared with a single application (2 g x kg(-1)) of paper mill sludge or red mud, Cd accumulation decreased significantly following the application of zinc fertilizer (0.2 g x kg(-1)) field experimental results were similar to the pot experiment that Cd accumulation apparently declined in the first and second crops (late rice and autumn rape) following the application of paper mill sludge, red mud and addition of zinc fertilizer. The Cd content in brown rice and rape seeds was decreased by 27.1-65.1% and 16.4%-41.6%, respectively, compared with no alkaline substances application. The Cd content in brown rice reached the National Hygienic Standard for Grains (GB 2715-2005). Therefore, combined application of paper mill sludge or red mud with zinc fertilizer was a feasible method to remediate acid cadmium contaminated paddy soil. Rice

  13. Haloarchaeal assimilatory nitrate-reducing communities from a saline alkaline soil.

    PubMed

    Alcántara-Hernández, Rocio J; Valenzuela-Encinas, César; Zavala-Díaz de la Serna, Francisco J; Rodriguez-Revilla, Javier; Dendooven, Luc; Marsch, Rodolfo

    2009-09-01

    Assimilatory nitrate reduction (ANR) is a pathway wherein NO(3)(-) is reduced to NH(4)(+), an N species that can be incorporated into the biomass. There is little information about the ANR genes in Archaea and most of the known information has been obtained from cultivable species. In this study, the diversity of the haloarchaeal assimilatory nitrate-reducing community was studied in an extreme saline alkaline soil of the former lake Texcoco (Mexico). Genes coding for the assimilatory nitrate reductase (narB) and the assimilatory nitrite reductase (nirA) were used as functional markers. Primers to amplify and detect partial narB and nirA were designed. The analysis of these amplicons by cloning and sequencing showed that the deduced protein fragments shared >45% identity with other NarB and NirA proteins from Euryarchaeota and <38% identity with other nitrate reductases from Bacteria and Crenarchaeota. Furthermore, these clone sequences were clustered within the class Halobacteria with strong support values in both constructed dendrograms, confirming that desired PCR products were obtained. The metabolic capacity to assimilate nitrate by these haloarchaea seems to be important given that at pH 10 and higher, NH(4)(+) is mostly converted to toxic and volatile NH(3), and NO(3)(-) becomes the preferable N source.

  14. Organic phosphorus fractions in organically amended paddy soils in continuously and intermittently flooded conditions.

    PubMed

    Yang, Changming; Yang, Linzhang; Jianhua, Lee

    2006-01-01

    Soil organic phosphorus (SOP) can greatly contribute to plant-available P and P nutrition. The study was conducted to determine the effects of organic amendments on organic P fractions and microbiological activities in paddy soils. Samples were collected at the Changshu Agro-ecological Experiment Station in Tahu Lake Basin, China, from an experiment that has been performed from 1999 to 2004, on a paddy soil (Gleysols). Treatments consisted of swine manure (SM), wheat straw (WS), swine manure plus wheat straw (SM + WS), and a control (chemical fertilization alone). Organic amendments markedly increased soil total organic phosphorus (TOP) and total organic carbon (TOC), especially in continuously flooded conditions. Based on the fractionation of SOP, organic amendments significantly increased soil labile organic phosphorus (LOP), moderately labile organic phosphorus (MLOP), and moderately stable organic phosphorus (MSOP) compared with the control. For SM and SM + WS treatments, LOP in continuously flooded soils decreased by 30.1 and 36.4%, respectively, compared to intermittently flooded soils. In organically amended soils, continuous flooding showed significantly lower microbial biomass phosphorus (MBP) and alkaline phosphatase activities (APA) than intermittent flooding. In intermittently flooded conditions, incorporating organic amendments into soil resulted in greater P uptake and biomass yield of rice than the control. In the intermittently flooded soils, APA (P < 0.05) and MBP (P < 0.01) were significantly and positively related to TOP, LOP, MLOP, and MSOP, whereas in continuously flooded soils, there was a significant (P < 0.05) negative relationship between MBP, TOP, and MSOP. Based on soil organic P fractions and soil enzymatic and microbiological activities, continuous flooding applied to paddy soils should be avoided, especially when swine manure is incorporated into paddy soil. PMID:16738400

  15. Bacterial Degradation of Cyanide and Its Metal Complexes under Alkaline Conditions

    PubMed Central

    Luque-Almagro, Víctor M.; Huertas, María-J.; Martínez-Luque, Manuel; Moreno-Vivián, Conrado; Roldán, M. Dolores; García-Gil, L. Jesús; Castillo, Francisco; Blasco, Rafael

    2005-01-01

    A bacterial strain able to use cyanide as the sole nitrogen source under alkaline conditions has been isolated. The bacterium was classified as Pseudomonas pseudoalcaligenes by comparison of its 16S RNA gene sequence to those of existing strains and deposited in the Colección Española de Cultivos Tipo (Spanish Type Culture Collection) as strain CECT5344. Cyanide consumption is an assimilative process, since (i) bacterial growth was concomitant and proportional to cyanide degradation and (ii) the bacterium stoichiometrically converted cyanide into ammonium in the presence of l-methionine-d,l-sulfoximine, a glutamine synthetase inhibitor. The bacterium was able to grow in alkaline media, up to an initial pH of 11.5, and tolerated free cyanide in concentrations of up to 30 mM, which makes it a good candidate for the biological treatment of cyanide-contaminated residues. Both acetate and d,l-malate were suitable carbon sources for cyanotrophic growth, but no growth was detected in media with cyanide as the sole carbon source. In addition to cyanide, P. pseudoalcaligenes CECT5344 used other nitrogen sources, namely ammonium, nitrate, cyanate, cyanoacetamide, nitroferricyanide (nitroprusside), and a variety of cyanide-metal complexes. Cyanide and ammonium were assimilated simultaneously, whereas cyanide strongly inhibited nitrate and nitrite assimilation. Cyanase activity was induced during growth with cyanide or cyanate, but not with ammonium or nitrate as the nitrogen source. This result suggests that cyanate could be an intermediate in the cyanide degradation pathway, but alternative routes cannot be excluded. PMID:15691951

  16. Density of alkaline magmas at crustal and upper mantle conditions by X-ray absorption

    NASA Astrophysics Data System (ADS)

    Seifert, R.; Malfait, W.; Petitgirard, S.; Sanchez-Valle, C.

    2011-12-01

    Silicate melts are essential components of igneous processes and are directly involved in differentiation processes and heat transfer within the Earth. Studies of the physical properties of magmas (e.g., density, viscosity, conductivity, etc) are however challenging and experimental data at geologically relevant pressure and temperature conditions remain scarce. For example, there is virtually no data on the density at high pressure of alkaline magmas (e.g., phonolites) typically found in continental rift zone settings. We present in situ density measurements of alkaline magmas at crustal and upper mantle conditions using synchrotron X-ray absorption. Measurements were conducted on ID27 beamline at ESRF using a panoramic Paris-Edinburgh Press (PE Press). The starting material is a synthetic haplo-phonolite glass similar in composition to the Plateau flood phonolites from the Kenya rift [1]. The glass was synthesized at 1673 K and 2.0 GPa in a piston-cylinder apparatus at ETH Zurich and characterized using EPMA, FTIR and density measurements. The sample contains less than 200 ppm water and is free of CO2. Single-crystal diamond cylinders (Øin = 0.5 mm, height = 1 mm) were used as sample containers and placed in an assembly formed by hBN spacers, a graphite heater and a boron epoxy gasket [2]. The density was determined as a function of pressure (1.0 to 3.1 GPa) and temperature (1630-1860 K) from the X-ray absorption contrast at 20 keV between the sample and the diamond capsule. The molten state of the sample during the data collection was confirmed by X-ray diffraction measurements. Pressure and temperature were determined simultaneously from the equation of state of hBN and platinum using the the double isochor method [3].The results are combined with available density data at room conditions to derive the first experimental equation of state (EOS) of phonolitic liquids at crustal and upper mantle conditions. We will compare our results with recent reports of the

  17. Biotoxicity of Mars soils: 1. Dry deposition of analog soils on microbial colonies and survival under Martian conditions

    NASA Astrophysics Data System (ADS)

    Schuerger, Andrew C.; Golden, D. C.; Ming, Doug W.

    2012-11-01

    Six Mars analog soils were created to simulate a range of potentially biotoxic geochemistries relevant to the survival of terrestrial microorganisms on Mars, and included basalt-only (non-toxic control), salt, acidic, alkaline, aeolian, and perchlorate rich geochemistries. Experiments were designed to simulate the dry-deposition of Mars soils onto spacecraft surfaces during an active descent landing scenario with propellant engines. Six eubacteria were initially tested for tolerance to desiccation, and the spore-former Bacillus subtilis HA101 and non-spore former Enterococcus faecalis ATCC 29212 were identified to be strongly resistant (HA101) and moderately resistant (29212) to desiccation at 24 °C. Furthermore, tests with B. subtilis and E. faecalis demonstrated that at least 1 mm of Mars analog soil was required to fully attenuate the biocidal effects of a simulated Mars-normal equatorial UV flux. Biotoxicity experiments were conducted under simulated Martian conditions of 6.9 mbar, -10 °C, CO2-enriched anoxic atmosphere, and a simulated equatorial solar spectrum (200-1100 nm) with an optical depth of 0.1. For B. subtilis, the six analog soils were found, in general, to be of low biotoxicity with only the high salt and acidic soils exhibiting the capacity to inactivate a moderate number of spores (<1 log reductions) exposed 7 days to the soils under simulated Martian conditions. In contrast, the overall response of E. faecalis to the analog soils was more dramatic with between two and three orders of magnitude reductions in viable cells for most soils, and between six and seven orders of magnitude reductions observed for the high-salt soil. Results suggest that Mars soils are likely not to be overtly biotoxic to terrestrial microorganisms, and suggest that the soil geochemistries on Mars will not preclude the habitability of the Martian surface.

  18. Ethanol production from glycerol-containing biodiesel waste by Klebsiella variicola shows maximum productivity under alkaline conditions.

    PubMed

    Suzuki, Toshihiro; Nishikawa, Chiaki; Seta, Kohei; Shigeno, Toshiya; Nakajima-Kambe, Toshiaki

    2014-05-25

    Biodiesel fuel (BDF) waste contains large amounts of crude glycerol as a by-product, and has a high alkaline pH. With regard to microbial conversion of ethanol from BDF-derived glycerol, bacteria that can produce ethanol at alkaline pH have not been reported to date. Isolation of bacteria that shows maximum productivity under alkaline conditions is essential to effective production of ethanol from BDF-derived glycerol. In this study, we isolated the Klebsiella variicola TB-83 strain, which demonstrated maximum ethanol productivity at alkaline pH. Strain TB-83 showed effective usage of crude glycerol with maximum ethanol production at pH 8.0-9.0, and the culture pH was finally neutralized by formate, a by-product. In addition, the ethanol productivity of strain TB-83 under various culture conditions was investigated. Ethanol production was more efficient with the addition of yeast extract. Strain TB-83 produced 9.8 g/L ethanol (0.86 mol/mol glycerol) from cooking oil-derived BDF waste. Ethanol production from cooking oil-derived BDF waste was higher than that of new frying oil-derived BDF and pure-glycerol. This is the first report to demonstrate that the K. variicola strain TB-83 has the ability to produce ethanol from glycerol at alkaline pH.

  19. The conversion of mineral celestite to strontianite under alkaline hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Suárez-Orduña, R.; Rendón-Angeles, J. C.; López-Cuevas, J.; Yanagisawa, K.

    2004-04-01

    The exchange of SO42- ions with CO32- ions in natural strontium sulfate (celestite) single crystals was investigated under alkaline hydrothermal conditions. The hydrothermal treatments were conducted using a stainless steel Teflon-lined vessel. Experiments were performed at different temperatures from 150 to 250 °C for various reaction times between 1 and 96 h with a molar ratio of CO32-/SO42- = 1, 5 and 10. Structural characterization of partially and completely converted strontianite (SrCO3) crystals was conducted by XRD, FTIR and SEM. X-ray diffraction results showed that under hydrothermal conditions the exchange of CO32- ions in celestite was completed at 250 °C in a Na2CO3 solution with a molar ratio CO32-/SO42- = 10 for 96 h, and celestite changed to strontianite. The morphology of the converted strontianite crystals depicted that the conversion proceeds without severe changes of the original shape and dimension of the crystals. A peculiar texture, however, consisting of elongated channels and tiny holes distributed randomly normal to the (001) cleavage plane, was formed in order to compensate the dimensional change of the lattice parameters associated with the conversion of celestite to strontianite. Details regarding the conversion mechanism are discussed in the present work.

  20. Salt- and alkaline-tolerance are linked in Acacia.

    PubMed

    Bui, Elisabeth N; Thornhill, Andrew; Miller, Joseph T

    2014-07-01

    Saline or alkaline soils present a strong stress on plants that together may be even more deleterious than alone. Australia's soils are old and contain large, sometimes overlapping, areas of high salt and alkalinity. Acacia and other Australian plant lineages have evolved in this stressful soil environment and present an opportunity to understand the evolution of salt and alkalinity tolerance. We investigate this evolution by predicting the average soil salinity and pH for 503 Acacia species and mapping the response onto a maximum-likelihood phylogeny. We find that salinity and alkalinity tolerance have evolved repeatedly and often together over 25 Ma of the Acacia radiation in Australia. Geographically restricted species are often tolerant of extreme conditions. Distantly related species are sympatric in the most extreme soil environments, suggesting lack of niche saturation. There is strong evidence that many Acacia have distributions affected by salinity and alkalinity and that preference is lineage specific.

  1. Microbial Reduction of Fe(III) under Alkaline Conditions Relevant to Geological Disposal

    PubMed Central

    Williamson, Adam J.; Morris, Katherine; Shaw, Sam; Byrne, James M.; Boothman, Christopher

    2013-01-01

    To determine whether biologically mediated Fe(III) reduction is possible under alkaline conditions in systems of relevance to geological disposal of radioactive wastes, a series of microcosm experiments was set up using hyperalkaline sediments (pH ∼11.8) surrounding a legacy lime working site in Buxton, United Kingdom. The microcosms were incubated for 28 days and held at pH 10. There was clear evidence for anoxic microbial activity, with consumption of lactate (added as an electron donor) concomitant with the reduction of Fe(III) as ferrihydrite (added as the electron acceptor). The products of microbial Fe(III) reduction were black and magnetic, and a range of analyses, including X-ray diffraction, transmission electron microscopy, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism confirmed the extensive formation of biomagnetite in this system. The addition of soluble exogenous and endogenous electron shuttles such as the humic analogue anthraquinone-2,6-disulfonate and riboflavin increased both the initial rate and the final extent of Fe(III) reduction in comparison to the nonamended experiments. In addition, a soluble humic acid (Aldrich) also increased both the rate and the extent of Fe(III) reduction. These results show that microbial Fe(III) reduction can occur in conditions relevant to a geological disposal facility containing cement-based wasteforms that has evolved into a high pH environment over prolonged periods of time (>100,000 years). The potential impact of such processes on the biogeochemistry of a geological disposal facility is discussed, including possible coupling to the redox conditions and solubility of key radionuclides. PMID:23524677

  2. Manganese peroxidases from Ganoderma applanatum degrade β-carotene under alkaline conditions.

    PubMed

    Lanfermann, Isabel; Linke, Diana; Nimtz, Manfred; Berger, Ralf G

    2015-04-01

    A β-carotene-degrading enzyme activity was observed in liquid cultures of the basidiomycete Ganoderma applanatum. Supplementing the cultures with β-carotene induced the bleaching activity. Purification via hydrophobic interaction, ion exchange and size exclusion chromatography followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) resulted in a single protein band. LC-ion-trap-MS analyses and gene amplification identified two manganese peroxidase isoenzymes with 97.8 % identity on the amino acid level. These showed an estimated molecular mass of 48 kDa and an isoelectric point of 2.6. Properties not yet described for other manganese peroxidases were hydrogen-peroxide-independent catalysis and two maxima of the bleaching activity, a distinct one at pH 5 and a lower one at pH 8. During simulated washing studies, the applicability of the isoenzymes for the brightening of carotenoids under alkaline conditions was proven. The new enzymes may replace common bleaching agents to produce environmentally more compatible detergent formulations.

  3. White-rot fungi capable of decolourising textile dyes under alkaline conditions.

    PubMed

    Ottoni, Cristiane A; Santos, Cledir; Kozakiewicz, Zofia; Lima, Nelson

    2013-05-01

    Twelve white-rot fungal strains belonging to seven different species were screened on plates under alkaline condition to study the decolourisation of the textile dyes Reactive Black 5 and Poly R-478. Three strains of Trametes versicolor (Micoteca da Universidade do Minho (MUM) 94.04, 04.100 and 04.101) and one strain of Phanerochaete chrysosporium (MUM 94.15) showed better decolourisation results. These four strains were used for decolourisation studies in liquid culture medium. All four selected strains presented more efficient decolourisation rates on Reactive Black 5 than on Poly R-478. For both dyes on solid and liquid culture media, the decolourisation capability exhibited by these strains depended on dye concentration and pH values of the media. Finally, the decolourisation of Reactive Black 5 by T. versicolor strains MUM 94.04 and 04.100 reached 100 %. In addition, the highest white-rot fungi ligninolytic enzyme activities were found for these two strains.

  4. Alkaline phosphatase activity related to phosphorus stress of microphytoplankton in different trophic conditions

    NASA Astrophysics Data System (ADS)

    Ivančić, Ingrid; Pfannkuchen, Martin; Godrijan, Jelena; Djakovac, Tamara; Marić Pfannkuchen, Daniela; Korlević, Marino; Gašparović, Blaženka; Najdek, Mirjana

    2016-08-01

    The northern Adriatic (NA) is a favorable basin for studying the adaptive strategies of plankton to a variety of conditions along the steep gradients of environmental parameters over the year. Earlier studies identified phosphorus (P)-limitation as one of the key stresses within the NA that shape the biological response in terms of biodiversity and metabolic adjustments. A wide range of reports supports the notion that P-limitation is a globally important phenomenon in aquatic ecosystems. In this study P stress of marine microphytoplankton was determined at species level along a trophic gradient in the NA. In P-limitation all species with considerable contributions to the diatom community expressed alkaline phosphatase activity (APA), compared to only a few marginal dinoflagellate species. Nevertheless, APA expressing species did not always dominate the phytoplankton community, suggesting that APA is also an important strategy for species to survive and maintain active metabolism outside of their mass abundances. A symbiotic relationship could be supposed for diatoms that did not express APA themselves and probably benefited from APA expressed by attached bacteria. APA was not expressed by any microphytoplankton species during the autumn when P was not limiting, while most of the species did express APA during the P-limitation. This suggests that APA expression is regulated by orthophosphate availability. The methods employed in this study allowed the microscopic detection of APA for each microphytoplankton cell with simultaneous morphologic/taxonomic analysis. This approach uncovered a set of strategies to compete in P-limited conditions within the marine microphytoplankton community. This study confirms the role of P-limitation as a shaping factor in marine ecosystems.

  5. The soil carbon/nitrogen ratio and moisture affect microbial community structures in alkaline permafrost-affected soils with different vegetation types on the Tibetan plateau.

    PubMed

    Zhang, Xinfang; Xu, Shijian; Li, Changming; Zhao, Lin; Feng, Huyuan; Yue, Guangyang; Ren, Zhengwei; Cheng, Guogdong

    2014-01-01

    In the Tibetan permafrost region, vegetation types and soil properties have been affected by permafrost degradation, but little is known about the corresponding patterns of their soil microbial communities. Thus, we analyzed the effects of vegetation types and their covariant soil properties on bacterial and fungal community structure and membership and bacterial community-level physiological patterns. Pyrosequencing and Biolog EcoPlates were used to analyze 19 permafrost-affected soil samples from four principal vegetation types: swamp meadow (SM), meadow (M), steppe (S) and desert steppe (DS). Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria dominated bacterial communities and the main fungal phyla were Ascomycota, Basidiomycota and Mucoromycotina. The ratios of Proteobacteria/Acidobacteria decreased in the order: SM>M>S>DS, whereas the Ascomycota/Basidiomycota ratios increased. The distributions of carbon and nitrogen cycling bacterial genera detected were related to soil properties. The bacterial communities in SM/M soils degraded amines/amino acids very rapidly, while polymers were degraded rapidly by S/DS communities. UniFrac analysis of bacterial communities detected differences among vegetation types. The fungal UniFrac community patterns of SM differed from the others. Redundancy analysis showed that the carbon/nitrogen ratio had the main effect on bacteria community structures and their diversity in alkaline soil, whereas soil moisture was mainly responsible for structuring fungal communities. Thus, microbial communities and their functioning are probably affected by soil environmental change in response to permafrost degradation.

  6. Computational Design of a pH Stable Enzyme: Understanding Molecular Mechanism of Penicillin Acylase's Adaptation to Alkaline Conditions

    PubMed Central

    Suplatov, Dmitry; Panin, Nikolay; Kirilin, Evgeny; Shcherbakova, Tatyana; Kudryavtsev, Pavel; Švedas, Vytas

    2014-01-01

    Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties. PMID:24959852

  7. Dependence of the cyclization of branched tetraethers on soil moisture in alkaline soils from arid-subhumid China: implications for palaeorainfall reconstructions on the Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Wang, H.; Liu, W.; Zhang, C. L.

    2014-12-01

    The use of branched glycerol dialkyl glycerol tetraethers (bGDGTs) in loess-palaeosol sequences (LPSs) has shown promises in continental palaeotemperature reconstructions. Thus far, however, little is known about the effect of soil moisture on their distributions in the water-limited Chinese Loess Plateau (CLP). In this study, the relationships between environmental variables and the cyclization of branched tetraethers (CBT) were investigated in arid-subhumid China using 97 surface soils in the CLP and its vicinity, as well as 78 soils with pH > 7 which have been previously published. We find that CBT correlates best with soil water content (SWC) or mean annual precipitation (MAP) for the overall data set. This indicates that CBT is mainly controlled by soil moisture instead of soil pH in alkaline soils from arid-subhumid regions, where water availability is a limiting factor for the producers of bGDGTs. Therefore, we suggest that CBT can potentially be used as a palaeorainfall proxy on the alkaline CLP. According to the preliminary CBT-MAP relationship for modern CLP soils (CBT = -0.0021 × MAP + 1.7, n = 37, r = -0.93), palaeorainfall history was reconstructed from three LPSs (Yuanbao, Lantian, and Mangshan) with published bGDGT data spanning the past 70 ka. The CBT-derived MAP records of the three sites consistently show precession-driven variation resembling the monsoon record based on speleothem δ18O, supporting CBT as a reasonable proxy for palaeorainfall reconstruction in LPS. The direct application of CBT as a palaeorainfall proxy in corroboration with the bGDGT-based temperature proxy may enable us to further assess the temperature/hydrological association for palaeoclimate studies on the CLP.

  8. Pseudomonas songnenensis sp. nov., isolated from saline and alkaline soils in Songnen Plain, China.

    PubMed

    Zhang, Lei; Pan, Yuanyuan; Wang, Kaibiao; Zhang, Xiaoxia; Zhang, Shuang; Fu, Xiaowei; Zhang, Cheng; Jiang, Juquan

    2015-03-01

    The strain NEAU-ST5-5(T) was isolated from the saline and alkaline soil in Songnen Plain, North East of China. The bacterium was found to be aerobic, Gram-stain negative, rod-shaped and motile by means of several polar flagella. It forms yellow-orange colonies with a radial wrinkled surface. Phylogenetic analyses based on the separate 16S rRNA gene sequences and concatenated 16S rRNA, gyrB and rpoD gene sequences indicated that it belongs to the genus Pseudomonas in the class Gammaproteobacteria. Strain NEAU-ST5-5(T) shows gene sequence similarities of 98.8-97.1 % for 16S rRNA, 90.5-78.4 % for gyrB and 90.4-71.1 % for rpoD with type strains of the closely related species of the genus Pseudomonas, respectively. DNA-DNA hybridization relatedness between strain NEAU-ST5-5(T) and type strains of the most closely related species, Pseudomonas stutzeri DSM 5190(T), P. xanthomarina DSM 18231(T), P. kunmingensis CGMCC 1.12273(T), P. alcaliphila DSM 17744(T) and P. oleovorans subsp. lubricantis DSM 21016(T) were 43 ± 1 to 25 ± 2 %. The major fatty acids (>10 %) were determined to be C18:1 ω7c/C18:1 ω6c, C16:1 ω7c/C16:1 ω6c and C16:0, the predominant respiratory quinone was identified as ubiquinone 9 and polar lipids were found to consist of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unknown phospholipid, one unidentified aminophospholipid and one unknown lipid. The genotypic, chemotaxonomic and phenotypic analysis indicated that strain NEAU-ST5-5(T) represents a novel species of the genus Pseudomonas, for which the name Pseudomonas songnenensis sp. nov. is proposed. The type strain is NEAU-ST5-5(T) (=ACCC 06361(T) = DSM 27560(T)). PMID:25550067

  9. Kocuria dechangensis sp. nov., an actinobacterium isolated from saline and alkaline soils.

    PubMed

    Wang, Kaibiao; Zhang, Lei; Liu, Yanshuang; Pan, Yuanyuan; Meng, Lin; Xu, Tong; Zhang, Cheng; Liu, Henan; Hong, Shan; Huang, Haipeng; Jiang, Juquan

    2015-09-01

    A Gram-stain positive, strictly aerobic, non-motile and coccus-shaped actinobacterium, designated strain NEAU-ST5-33(T), was isolated from saline and alkaline soils in Dechang Township, Zhaodong City, PR China. It formed beige-yellow colonies and grew at NaCl concentrations of 0-5% (w/v) (optimum 0%), at pH 6.0-9.0 (optimum pH 7.0) and over a temperature range of 4-50 °C (optimum 35 °C). Based on 16S rRNA gene sequence analysis, strain NEAU-ST5-33(T) was phylogenetically closely related to the type strains of species of the genus Kocuria, Kocuria polaris CMS 76or(T), Kocuria rosea DSM 20447(T), Kocuria turfanensis HO-9042(T), Kocuria aegyptia YIM 70003(T), Kocuria himachalensis K07-05(T) and Kocuria flava HO-9041(T), with respective sequence similarities of 98.8%, 98.8%, 98.3%, 98.1%, 98.1% and 97.9%. DNA-DNA hybridization relatedness values of strain NEAU-ST5-33(T) with type strains of the closely related species ranged from 54 ± 1% to 34 ± 1%. The DNA G+C content was 61.2 mol%. The major fatty acids (>5%) were C15 : 0 anteiso, C15 : 0 iso and C16 : 1ω7c and/or C16 : 1ω6c. The major menaquinone detected was MK-8 (H2), and the polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, one unknown aminolipid and one unknown lipid. On the basis of the genotypic, chemotaxonomic and phenotypic data, we propose that strain NEAU-ST5-33(T) represents a novel species of the genus Kocuria, with the name Kocuria dechangensis sp. nov. The type strain is NEAU-ST5-33(T) ( = CGMCC 1.12187(T) = DSM 25872(T)). PMID:26048314

  10. Halomonas heilongjiangensis sp. nov., a novel moderately halophilic bacterium isolated from saline and alkaline soil.

    PubMed

    Dou, Guiming; He, Wei; Liu, Hongcan; Ma, Yuchao

    2015-08-01

    A moderately halophilic bacterium, designated strain 9-2(T), was isolated from saline and alkaline soil collected in Lindian county, Heilongjiang province, China. The strain was observed to be strictly aerobic, Gram-negative, rod-shaped, oxidase-positive, catalase-positive and motile. It was found to require NaCl for growth and to grow at NaCl concentrations of 0.5-14 % (w/v) (optimum, 7-10 %, w/v), at temperatures of 10-45 °C (optimum 25-30 °C) and at pH 5.0-10.0 (optimum pH 8.0). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 9-2(T) is a member of the genus Halomonas and is closely related to Halomonas desiderata DSM 9502(T) (96.68 %), Halomonas campaniensis DSM 1293(T) (96.46 %), Halomonas ventosae DSM 15911(T) (96.27 %) and Halomonas kenyensis DSM 17331(T) (96.27 %). The DNA-DNA hybridization value was 38.9 ± 0.66 % between the novel isolate 9-2(T) and H. desiderata DSM 9502(T). The predominant ubiquinones were identified as Q9 (75.1 %) and Q8 (24.9 %). The major fatty acids were identified as C16:0 (22.0 %), Summed feature 8 (C18:1 ω6c/C18:1 ω7c, 19.6 %), Summed feature 3 (C16:1 ω6c/C16:1 ω7c, 12.6 %), C12:0 3-OH (12.0 %) and C10:0 (11.7 %). The DNA G+C content was determined to be 69.7 mol%. On the basis of the evidence presented in this study, strain 9-2(T) is considered to represent a novel species of the genus Halomonas, for which the name Halomonas heilongjiangensis sp. nov. is proposed. The type strain is 9-2(T) (=DSM 26881(T) = CGMCC 1.12467(T)). PMID:26036672

  11. An investigation on magnetic susceptibility of hazardous saline-alkaline soils from the contaminated Hai River Basin, China.

    PubMed

    Yang, Pingguo; Mao, Renzhao; Shao, Hongbo

    2009-12-15

    Magnetic susceptibility can provide rich environmental information, especially for hazardous heavy metals and saline-alkaline in the contaminated soils. Magnetic susceptibility in four vertical profiles from saline-alkaline soils in lower Hai River basin was investigated. Soil sites were extended from alluvial fan to coastal plain areas. They are aligned along a latitudinal strip. Magnetic parameters including low/high frequency susceptibility, frequency-dependent susceptibility was measured. Moreover, some standard pedological parameters such as pH value and organic matter content were also determined. The results showed that low frequency magnetic susceptibility values is very high at the surface and decreases with the profile to a low value. In all profiles from alluvial fan frequency-dependent susceptibility greater than 3% may suggest the presence of relatively more super-paramagnetic particles. Magnetic susceptibility showed obvious vertical distribution in alluvial fan higher than coastal plain. No significant correlations between organic matter, pH and low frequency magnetic susceptibility were found, while there is a negative correlation between organic matter and frequency-dependent susceptibility. A positive correlation between pH and frequency-dependent susceptibility was found in the study areas. PMID:19643536

  12. Phylogenetic analysis of the archaeal community in an alkaline-saline soil of the former lake Texcoco (Mexico).

    PubMed

    Valenzuela-Encinas, César; Neria-González, Isabel; Alcántara-Hernández, Rocio J; Enríquez-Aragón, J Arturo; Estrada-Alvarado, Isabel; Hernández-Rodríguez, César; Dendooven, Luc; Marsch, Rodolfo

    2008-03-01

    The soil of the former lake Texcoco is an extreme environment localized in the valley of Mexico City, Mexico. It is highly saline and alkaline, where Na+, Cl(-), HCO3(-) and CO3(2-) are the predominant ions, with a pH ranging from 9.8 to 11.7 and electrolytic conductivities in saturation extracts from 22 to 150 dS m(-1). Metagenomic DNA from the archaeal community was extracted directly from soil and used as template to amplify 16S ribosomal gene by PCR. PCR products were used to construct gene libraries. The ribosomal library showed that the archaeal diversity included Natronococcus sp., Natronolimnobius sp., Natronobacterium sp., Natrinema sp., Natronomonas sp., Halovivax sp., "Halalkalicoccus jeotgali" and novel clades within the family of Halobacteriaceae. Four clones could not be classified. It was found that the archaeal diversity in an alkaline-saline soil of the former lake Texcoco, Mexico, was low, but showed yet uncharacterized and unclassified species.

  13. Respiratory and dissimilatory nitrate-reducing communities from an extreme saline alkaline soil of the former lake Texcoco (Mexico).

    PubMed

    Alcántara-Hernández, Rocio J; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc

    2009-01-01

    The diversity of the dissimilatory and respiratory nitrate-reducing communities was studied in two soils of the former lake Texcoco (Mexico). Genes encoding the membrane-bound nitrate reductase (narG) and the periplasmic nitrate reductase (napA) were used as functional markers. To investigate bacterial communities containing napA and narG in saline alkaline soils of the former lake Texcoco, libraries of the two sites were constructed (soil T3 with pH 11 and electrolytic conductivity in saturated extract (EC(SE)) 160 dS m(-1) and soil T1 with pH 8.5 and EC(SE) 0.8 dS m(-1)). Phylogenetic analysis of napA sequences separated the clone families into two main groups: dependent or independent of NapB. Most of napA sequences from site T1 were grouped in the NapB-dependent clade, meanwhile most of the napA sequences from the extreme soil T3 were affiliated to the NapB-independent group. For both sites, partial narG sequences were associated with representatives of the Proteobacteria, Firmicutes and Actinobacteria phyla, but the proportions of the clones were different. Our results support the concept of a specific and complex nitrate-reducing community for each soil of the former lake Texcoco.

  14. Effect of nitrogen, phosphorus and potassium availability on emergence, nodulation and growth of Trifolium medium L. in alkaline soil.

    PubMed

    Chmelíková, L; Hejcman, M

    2014-07-01

    Little is known about the effects of nutrient availability on the growth of Trifolium medium in alkaline soil. In 2010, a pot experiment (10 N, P and K fertiliser treatments) with seeding of T. medium into alkaline soil was performed and emergence of seedlings, survival, aboveground and belowground organs were studied. The positive effects of increased nutrient availability on seedling emergence ranged from 5% in the control to 17% in the high P treatment. The lowest mortality was in treatments with P and K supply and the highest in treatments with N supply, due to the sensitivity of young plants to high N availability. The highest values of most measured aboveground plant traits were recorded in treatments with simultaneous application of N, P and K. There were highly positive effects of P supply alone or in combination with N and K on the development of belowground organs. Taproot length ranged from 11.5 in high N to 40.2 cm in P treatment. There was a negative effect of N application on nodulation, especially in N treatments, where growth of T. medium was limited by insufficient P supply. The number of nodules per plant ranged from 0.8 to 4.5 in the high N and P treatments. As demonstrated in this study, T. medium is a potentially suitable legume for alkaline soils. It requires a relatively high P and K supply as well as moderate mineral N supply to achieve its maximum growth potential. PMID:24355109

  15. The regulators of yeast PHO system participate in the transcriptional regulation of G1 cyclin under alkaline stress conditions.

    PubMed

    Nishizawa, Masafumi

    2015-03-01

    The yeast Pho85 kinase oversees whether environmental conditions are favourable for cell growth and enables yeast cells to express only genes that are appropriate for the conditions. Alkaline stress perturbs transport of molecules across the plasma membrane that is vital for cell survival. Progression through the cell cycle is halted until the cells can adapt to the stress conditions. I found that Pho85 is required for CLN2 expression and that overproduction of the transcription factors Pho4, Rim101 and Crz1, all targets of Pho85, inhibited CLN2 expression. CLN2 expression in the absence of Pho85 could be recovered only when all the three transcription factors were deleted. Whi5, a functional homologue of the mammalian Rb protein, represses CLN2 expression and is inactivated when phosphorylated by either of the CDK-cyclin complexes, Cdc28-Cln3 or Pho85-Pcl9. Under alkaline conditions, the absence of Whi5 caused an increase in CLN2 expression but failed to do so when Pho85 was also absent, or when Pho4 was overproduced. The expression level of CLN2 in a Δpho85 Δpho4 Δrim101 Δcrz1 quadruple mutant was stimulated when the Whi5 activity was repressed by overproduction of Pho85-Pcl9. These results indicate that Whi5 is also under control of alkaline stress. The inhibitory function of Whi5 on CLN2 is dependent on Rpd3 HDAC, and the absence of Rpd3 could also suppress the inhibitory effect of Pho4 overproduction. Based on these findings, a model is presented in which Pho85 and Pho4 functions in CLN2 regulation under alkaline conditions.

  16. Tested Demonstrations. The Stepwise Reduction of Permanganate in Alkaline Conditions: A Lecture Demonstration.

    ERIC Educational Resources Information Center

    Ruoff, Peter; Riley, Megan

    1987-01-01

    Describes a chemistry experiment where an alkaline ice-cold permanganate solution is reduced by adding dropwise a cold diluted hydrogen peroxide solution. Outlines the course of the reduction through the various oxidation states of manganese with their characteristic colors. (TW)

  17. Diversity and food web structure of nematode communities under high soil salinity and alkaline pH.

    PubMed

    Salamún, Peter; Kucanová, Eva; Brázová, Tímea; Miklisová, Dana; Renčo, Marek; Hanzelová, Vladimíra

    2014-10-01

    A long-term and intensive magnesium (Mg) ore processing in Slovenské Magnezitové Závody a.s. in Jelšava has resulted in a high Mg content and alkaline pH of the soil environment, noticeable mainly in the close vicinity of the smelter. Nematode communities strongly reacted to the contamination mostly by a decrease in abundance of the sensitive groups. Nematodes from c-p 1 group and bacterivores, tolerant to pollution played a significant role in establishing the dominance at all sites. With increasing distance from the pollution source, the nematode communities were more structured and complex, with an increase in proportion of sensitive c-p 4 and 5 nematodes, composed mainly of carnivores and omnivores. Various ecological indices (e.g. MI2-5, SI, H') indicated similar improvement of farther soil ecosystems.

  18. Chemical speciation of neptunium(VI) under strongly alkaline conditions. Structure, composition, and oxo ligand exchange.

    PubMed

    Clark, David L; Conradson, Steven D; Donohoe, Robert J; Gordon, Pamela L; Keogh, D Webster; Palmer, Phillip D; Scott, Brian L; Tait, C Drew

    2013-04-01

    Hexavalent neptunium can be solubilized in 0.5-3.5 M aqueous MOH (M = Li(+), Na(+), NMe4(+) = TMA(+)) solutions. Single crystals were obtained from cooling of a dilute solution of Co(NH3)6Cl3 and NpO2(2+) in 3.5 M [N(Me)4]OH to 5 °C. A single-crystal X-ray diffraction study revealed the molecular formula of [Co(NH3)6]2[NpO2(OH)4]3·H2O, isostructural with the uranium analogue. The asymmetric unit contains three distinct NpO2(OH)4(2-) ions, each with pseudooctahedral coordination geometry with trans-oxo ligands. The average Np═O and Np-OH distances were determined to be 1.80(1) and 2.24(1) Å, respectively. EXAFS data and fits at the Np L(III)-edge on solid [Co(NH3)6]2[NpO2(OH)4]3·H2O and aqueous solutions of NpO2(2+) in 2.5 and 3.5 M (TMA)OH revealed bond lengths nearly identical with those determined by X-ray diffraction but with an increase in the number of equatorial ligands with increasing (TMA)OH concentration. Raman spectra of single crystals of [Co(NH3)6]2[NpO2(OH)4]3·H2O reveal a ν1(O═Np═O) symmetric stretch at 741 cm(-1). Raman spectra of NpO2(2+) recorded in a 0.6-2.2 M LiOH solution reveal a single ν1 frequency of 769 cm(-1). Facile exchange of the neptunyl oxo ligands with the water solvent was also observed with Raman spectroscopy performed with (16)O- and (18)O-enriched water solvent. The combination of EXAFS and Raman data suggests that NpO2(OH)4(2-) is the dominant solution species under the conditions of study and that a small amount of a second species, NpO2(OH)5(3-), may also be present at higher alkalinity. Crystal data for [Co(NH3)6]2[NpO2(OH)4]3·H2O: monoclinic, space group C2/c, a = 17.344(4) Å, b = 12.177(3) Å, c = 15.273 Å, β = 120.17(2)°, Z = 4, R1 = 0.0359, wR2 = 0.0729.

  19. Quantitative Proteomic Analysis of Germination of Nosema bombycis Spores under Extremely Alkaline Conditions

    PubMed Central

    Liu, Han; Chen, Bosheng; Hu, Sirui; Liang, Xili; Lu, Xingmeng; Shao, Yongqi

    2016-01-01

    The microsporidian Nosema bombycis is an obligate intracellular pathogen of the silkworm Bombyx mori, causing the epidemic disease Pebrine and extensive economic losses in sericulture. Although N. bombycis forms spores with rigid spore walls that protect against various environmental pressures, ingested spores germinate immediately under the extremely alkaline host gut condition (Lepidoptera gut pH > 10.5), which is a key developmental turning point from dormant state to infected state. However, to date this process remains poorly understood due to the complexity of the animal digestive tract and the lack of genetic tools for microsporidia. Here we show, using an in vitro spore germination model, how the proteome of N. bombycis changes during germination, analyse specific metabolic pathways employed in detail, and validate key functional proteins in vivo in silkworms. By a label-free quantitative proteomics approach that is directly based on high-resolution mass spectrometry (MS) data, a total of 1136 proteins were identified with high confidence, with 127 proteins being significantly changed in comparison to non-germinated spores. Among them, structural proteins including polar tube protein 1 and 3 and spore wall protein (SWP) 4 and 30 were found to be significantly down-regulated, but SWP9 significantly up-regulated. Some nucleases like polynucleotide kinase/phosphatase and flap endonucleases 1, together with a panel of hydrolases involved in protein degradation and RNA cleavage were overrepresented too upon germination, which implied that they might play important roles during spore germination. The differentially regulated trends of these genes were validated, respectively, by quantitative RT-PCR and 3 proteins of interest were confirmed by Western blotting analyses in vitro and in vivo. Furthermore, the pathway analysis showed that abundant up- and down-regulations appear involved in the glycolysis, pentose phosphate pathway, purine, and pyrimidine metabolism

  20. The effect of Penicillium fungi on plant growth and phosphorus mobilization in neutral to alkaline soils from southern Australia.

    PubMed

    Wakelin, S A; Gupta, V V S R; Harvey, P R; Ryder, M H

    2007-01-01

    The phosphate solubilizing fungi Penicillium radicum, Penicillium bilaiae (strain RS7B-SD1), and an unidentified Penicillium sp. designated strain KC6-W2 were tested for their ability to increase the growth and phosphorus (P) nutrition of wheat, medic, and lentil in three soils of neutral to alkaline pH reaction. The strongest plant growth promoting (PGP) strain was Penicillium sp. KC6-W2, which stimulated significant increases in shoot growth and dry mass in seven of the nine experiments conducted. Levels of PGP by Penicillium sp. KC6-W2 ranged from 6.6% to 19% and were associated with increased uptake of P to the shoot. The PGP properties of Penicillium sp. KC6-W2 were evident on each of the three different plant species and soil types, a level of reliability not observed in other strains tested. Inoculation of seed with P. radicum increased lentil growth by 5.5% (P < 0.05) in soil from Tarlee but did not affect plant growth in the eight other experiments. Inoculation of plant seed with P. bilaiae RS7B-SD1 resulted in significant PGP in two of the nine experiments conducted. However, when significant, stimulation of PGP by P. bilaiae RS7B-SD1 was strong and resulted in increases in medic dry matter (19%) and lentil shoot dry matter (15%). A soil microcosm experiment investigated the effect of Penicillium fungi on cycling of soil P. Penicillium bilaiae RS7B-SD1 was the only fungus to significantly increase HCO3-extractable P (23% increase; P < 0.05). Production of phosphatase enzymes was not associated with increased HCO3-extractable P. Addition of carbon in the form of ryegrass seed significantly increased microbial respiration and movement of P to the microbial biomass (P < 0.05), but these parameters were irrespective of Penicillium treatment. This work has established the potential for use of Penicillium inoculants to increase plant growth on alkaline soils in Australia. The role of Penicillium fungi in plant P uptake and soil P cycling requires further

  1. Evidence of the generation of isosaccharinic acids and their subsequent degradation by local microbial consortia within hyper-alkaline contaminated soils, with relevance to intermediate level radioactive waste disposal.

    PubMed

    Rout, Simon P; Charles, Christopher J; Garratt, Eva J; Laws, Andrew P; Gunn, John; Humphreys, Paul N

    2015-01-01

    The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration.

  2. Evidence of the Generation of Isosaccharinic Acids and Their Subsequent Degradation by Local Microbial Consortia within Hyper-Alkaline Contaminated Soils, with Relevance to Intermediate Level Radioactive Waste Disposal

    PubMed Central

    Rout, Simon P.; Charles, Christopher J.; Garratt, Eva J.; Laws, Andrew P.; Gunn, John; Humphreys, Paul N.

    2015-01-01

    The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration. PMID:25748643

  3. Evidence of the generation of isosaccharinic acids and their subsequent degradation by local microbial consortia within hyper-alkaline contaminated soils, with relevance to intermediate level radioactive waste disposal.

    PubMed

    Rout, Simon P; Charles, Christopher J; Garratt, Eva J; Laws, Andrew P; Gunn, John; Humphreys, Paul N

    2015-01-01

    The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration. PMID:25748643

  4. Anditalea andensis ANESC-ST - An Alkaliphilic Halotolerant Bacterium Capable of Electricity Generation under Alkaline-Saline Conditions

    PubMed Central

    Shi, Wei; Wang, Victor Bochuan; Zhao, Cui-E; Zhang, Qichun; Loo, Say Chye Joachim; Yang, Liang; Xu, Chenjie

    2015-01-01

    A great challenge in wastewater bioremediation is the sustained activity of viable microorganisms, which can contribute to the breakdown of waste contaminants, especially in alkaline pH conditions. Identification of extremophiles with bioremediation capability can improve the efficiency of wastewater treatment. Here, we report the discovery of an electrochemically active alkaliphilic halotolerant bacterium, Anditalea andensis ANESC-ST (=CICC10485T=NCCB 100412T), which is capable of generating bioelectricity in alkaline–saline conditions. A. andensis ANESC-ST was shown to grow in alkaline conditions between pH 7.0–11.0 and also under high salt condition (up to 4 wt% NaCl). Electrical output was further demonstrated in microbial fuel cells (MFCs) with an average current density of ~0.5 µA/cm2, even under the harsh condition of 4 wt% NaCl and pH 9.0. Subsequent introduction of secreted extracellular metabolites into MFCs inoculated with Escherichia coli or Pseudomonas aeruginosa yielded enhanced electrical output. The ability of A. andensis ANESC-ST to generate energy under alkaline–saline conditions points towards a solution for bioelectricity recovery from alkaline–saline wastewater. This is the first report of A.andensis ANESC-ST producing bioelectricity at high salt concentration and pH. PMID:26171779

  5. Phosphorus Release to Floodwater from Calcareous Surface Soils and Their Corresponding Subsurface Soils under Anaerobic Conditions.

    PubMed

    Jayarathne, P D K D; Kumaragamage, D; Indraratne, S; Flaten, D; Goltz, D

    2016-07-01

    Enhanced phosphorus (P) release from soils to overlying water under flooded, anaerobic conditions has been well documented for noncalcareous and surface soils, but little information is available for calcareous and subsurface soils. We compared the magnitude of P released from 12 calcareous surface soils and corresponding subsurface soils to overlying water under flooded, anaerobic conditions and examined the reasons for the differences. Surface (0-15 cm) and subsurface (15-30 cm) soils were packed into vessels and flooded for 8 wk. Soil redox potential and concentrations of dissolved reactive phosphorus (DRP) and total dissolved Ca, Mg, Fe, and Mn in floodwater and pore water were measured weekly. Soil test P was significantly smaller in subsurface soils than in corresponding surface soils; thus, the P release to floodwater from subsurface soils was significantly less than from corresponding surface soils. Under anaerobic conditions, floodwater DRP concentration significantly increased in >80% of calcareous surface soils and in about 40% of subsurface soils. The increase in floodwater DRP concentration was 2- to 17-fold in surface soils but only 4- to 7-fold in subsurface soils. With time of flooding, molar ratios of Ca/P and Mg/P in floodwater increased, whereas Fe/P and Mn/P decreased, suggesting that resorption and/or reprecipitation of P took place involving Fe and Mn. Results indicate that P release to floodwater under anaerobic conditions was enhanced in most calcareous soils. Surface and subsurface calcareous soils in general behaved similarly in releasing P under flooded, anaerobic conditions, with concentrations released mainly governed by initial soil P concentrations. PMID:27380087

  6. Comparing Soil Organic Carbon Dynamics in Perennial Grasses and Shrubs in a Saline-Alkaline Arid Region, Northwestern China

    PubMed Central

    Su, Jiaqi; Zhang, Jingli; Zheng, Yuanrun; Ni, Jian; Xiao, Chunwang; Wang, Renzhong

    2012-01-01

    Background Although semi-arid and arid regions account for about 40% of terrestrial surface of the Earth and contain approximately 10% of the global soil organic carbon stock, our understanding of soil organic carbon dynamics in these regions is limited. Methodology/Principal Findings A field experiment was conducted to compare soil organic carbon dynamics between a perennial grass community dominated by Cleistogenes squarrosa and an adjacent shrub community co-dominated by Reaumuria soongorica and Haloxylon ammodendron, two typical plant life forms in arid ecosystems of saline-alkaline arid regions in northwestern China during the growing season 2010. We found that both fine root biomass and necromass in two life forms varied greatly during the growing season. Annual fine root production in the perennial grasses was 45.6% significantly higher than in the shrubs, and fine root turnover rates were 2.52 and 2.17 yr−1 for the perennial grasses and the shrubs, respectively. Floor mass was significantly higher in the perennial grasses than in the shrubs due to the decomposition rate of leaf litter in the perennial grasses was 61.8% lower than in the shrubs even though no significance was detected in litterfall production. Soil microbial biomass and activity demonstrated a strong seasonal variation with larger values in May and September and minimum values in the dry month of July. Observed higher soil organic carbon stocks in the perennial grasses (1.32 Kg C m−2) than in the shrubs (1.12 Kg C m−2) might be attributed to both greater inputs of poor quality litter that is relatively resistant to decay and the lower ability of microorganism to decompose these organic matter. Conclusions/Significance Our results suggest that the perennial grasses might accumulate more soil organic carbon with time than the shrubs because of larger amounts of inputs from litter and slower return of carbon through decomposition. PMID:22900067

  7. Mechanisms involved in soil conditioning by polymers

    SciTech Connect

    Wallace, A.; Wallace, G.A.; Cha, J.W.

    1986-05-01

    Three different soils (two sodic and calcareous and one very acid and serpentine-like) was mixed with polyanion and polycation polymers and with a polysaccharide in suspension and passed the flocculated particles through sieves of different size openings for measurement of components. Including (NH/sub 4/)/sub 2/SO/sub 4/ in the suspension resulted in more complete flocculation with high pH soils and less with the acid soil. In contrast, with the polycation the (NH/sub 4/)/sub 2/SO/sub 4/ resulted in less flocculation for all three soils. Liming the acid soil to pH 7 increased flocculation for both the polyanion and the polycation. The polyanion resulted in more flocculation on calcareous than on acid soil, and the reverse occurred for the polycation. These results indicate that the salt effect was that of bringing clay particles closely enough together so that several of them could be bound with a common polyanion. The binding then would occur many times with polyanions for each aggregate of clay particles. Ion bridging is an important phenomenon in which polyvalent cations may be shared with polymer and clay in the flocculation-aggregation process. The addition of a polysaccharide with the polyanion gives additive to synergistic responses, indicating that there is cross-linking between the two polymers. The total effect resembles a brush heap that secures stability for the flocculated particles.

  8. Chemical stabilization of cadmium in acidic soil using alkaline agronomic and industrial by-products.

    PubMed

    Chang, Yao-Tsung; Hsi, Hsing-Cheng; Hseu, Zeng-Yei; Jheng, Shao-Liang

    2013-01-01

    In situ immobilization of heavy metals using reactive or stabilizing materials is a promising solution for soil remediation. Therefore, four agronomic and industrial by-products [wood biochar (WB), crushed oyster shell (OS), blast furnace slag (BFS), and fluidized-bed crystallized calcium (FBCC)] and CaCO3 were added to acidic soil (Cd = 8.71 mg kg(-1)) at the rates of 1%, 2%, and 4% and incubated for 90 d. Chinese cabbage (Brassica chinensis L.) was then planted in the soil to test the Cd uptake. The elevation in soil pH caused by adding the by-products produced a negative charge on the soil surface, which enhanced Cd adsorption. Consequently, the diethylenetriamine pentaacetic acid (DTPA)-extractable Cd content decreased significantly (P < 0.05) in the incubated soil. These results from the sequential extraction procedure indicated that Cd converted from the exchangeable fraction to the carbonate or Fe-Mn oxide fraction. The long-term effectiveness of Cd immobilization caused by applying the 4 by-products was much greater than that caused by applying CaCO3. Plant shoot biomass clearly increased because of the by-product soil amendment. Cd concentration in the shoots was < 10.0 mg kg(-1) following by-product application, as compared to 24 mg kg(-1) for plants growing in unamended soil. PMID:23947715

  9. FUNGUS INDEX AND RESIDUAL EFFECTS OF PESTICIDES IN ACID AND ALKALINE SOILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil applied pesticides have profound effects on the population density and diversity of fungi, however, such information is lacking in tropical soils of the Amazon region. Field experiments were implemented at two experimental farms ("El Choclito", "Bello Horizonte”) of Tropical Crop Institute (ICT...

  10. Assessment of possibilities and conditions of irrigation in Hungary by digital soil map products

    NASA Astrophysics Data System (ADS)

    Laborczi, Annamária; Bakacsi, Zsófia; Takács, Katalin; Szatmári, Gábor; Szabó, József; Pásztor, László

    2016-04-01

    Sustaining proper soil moisture is essentially important in agricultural management. However, irrigation can be really worth only, if we lay sufficient emphasis on soil conservation. Nationwide planning of irrigation can be taken place, if we have spatially exhaustive maps and recommendations for the different areas. Soil moisture in the pores originate from 'above' (precipitation), or from 'beneath' (from groundwater by capillary lift). The level of groundwater depends on topography, climatic conditions and water regime of the nearby river. The thickness of capillary zone is basicly related to the physical and water management properties of the soil. Accordingly the capillary rise of sandy soils - with very high infiltration rate and very poor water retaining capacity - are far smaller than in the case of clay soils - with very poor infiltration rate and high water retaining capacity. Applying irrigation water can be considered as a reinforcement from 'above', and it affects the salinity and sodicity as well as the soil structure, nutrient supply and soil formation. We defined the possibilities of irrigation according to the average salt content of the soil profile. The nationwide mapping of soil salinity was based on legacy soil profile data, and it was carried out by regression kriging. This method allows that environmental factors with exhaustive spatial extension, such as climatic-, vegetation-, topographic-, soil- and geologic layers can be taken into consideration to the spatial extension of the reference data. According to soil salinity content categories, the areas were delineated as 1. to be irrigated, 2. to be irrigated conditionally, 3. not to be irrigated. The conditions of irrigation was determined by the comparison of the 'actual' and the 'critical' depth of the water table. Since, if the water rises above the critical level, undesirable processes, such as salinization and alkalinization can be developed. The critical depth of the water table was

  11. Acclimatization of microbial consortia to alkaline conditions and enhanced electricity generation.

    PubMed

    Zhang, Enren; Zhai, Wenjing; Luo, Yue; Scott, Keith; Wang, Xu; Diao, Guowang

    2016-07-01

    Air-cathode microbial fuel cells (MFCs), obtained by inoculating with an aerobic activated sludge, were activated over a one month period, at pH 10.0, to obtain alkaline MFCs. The alkaline MFCs produced stable power of 118mWm(-2) and a maximum power density of 213mWm(-2) at pH 10.0, using glucose as substrate. The performance of the MFCs was enhanced to produce a stable power of 140mWm(-2) and a maximum power density of 235mWm(-2) by increasing pH to 11.0. This is the highest pH for stably operating MFCs reported in the literature. Power production was found to be suppressed at higher pH (12.0) and lower pH (9.0). Microbial analysis indicated that Firmicutes phylum was largely enriched in the anodic biofilms (88%), within which Eremococcus genus was the dominant group (47%). It is the first time that Eremococcus genus was described in bio-electrochemical systems.

  12. Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management

    NASA Astrophysics Data System (ADS)

    Udeigwe, Theophilus K.; Eichmann, Madeleine; Menkiti, Matthew C.

    2016-07-01

    This study was designed to examine the fixation pattern and kinetics of zinc (Zn) in chelated (ethylenediaminetetraacetic acid, EDTA) and non-chelated mixed micronutrient systems of semi-arid alkaline soils from the Southern High Plains, USA. Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models. About 30 % more plant-available Zn was fixed in the non-chelated system within the first 14 days with only about 18 % difference observed between the two systems by day 90, suggesting that the effectiveness of the chelated compounds tended to decrease over time. The strengths of the relationships of change in available Zn with respect to other micronutrients (copper, iron, and manganese) were higher and more significant in the non-chelated system (average R2 of 0.83), compared to the chelated (average R2 of 0.42). Fixation of plant-available Zn was best described by the power-function model (R2 = 0.94, SE = 0.076) in the non-chelated system, and was poorly described by all the models examined in the chelated system. Reaction rate constants and relationships generated from this study can serve as important tools for micronutrient management and for future micronutrient modeling studies on these soils and other semi-arid regions of the world.

  13. Synergistic interaction of Rhizobium leguminosarum bv. viciae and arbuscular mycorrhizal fungi as a plant growth promoting biofertilizers for faba bean (Vicia faba L.) in alkaline soil.

    PubMed

    Abd-Alla, Mohamed Hemida; El-Enany, Abdel-Wahab Elsadek; Nafady, Nivien Allam; Khalaf, David Mamdouh; Morsy, Fatthy Mohamed

    2014-01-20

    Egyptian soils are generally characterized by slightly alkaline to alkaline pH values (7.5-8.7) which are mainly due to its dry environment. In arid and semi-arid regions, salts are less concentrated and sodium dominates in carbonate and bicarbonate forms, which enhance the formation of alkaline soils. Alkaline soils have fertility problems due to poor physical properties which adversely affect the growth and the yield of crops. Therefore, this study was devoted to investigating the synergistic interaction of Rhizobium and arbuscular mycorrhizal fungi for improving growth of faba bean grown in alkaline soil. A total of 20 rhizobial isolates and 4 species of arbuscular mycorrhizal fungi (AMF) were isolated. The rhizobial isolates were investigated for their ability to grow under alkaline stress. Out of 20 isolates 3 isolates were selected as tolerant isolates. These 3 rhizobial isolates were identified on the bases of the sequences of the gene encoding 16S rRNA and designated as Rhizobium sp. Egypt 16 (HM622137), Rhizobium sp. Egypt 27 (HM622138) and Rhizobium leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The best alkaline tolerant was R. leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The effect of R. leguminosarum bv. viciae STDF-Egypt 19 and mixture of AMF (Acaulospora laevis, Glomus geosporum, Glomus mosseae and Scutellospora armeniaca) both individually and in combination on nodulation, nitrogen fixation and growth of Vicia faba under alkalinity stress were assessed. A significant increase over control in number and mass of nodules, nitrogenase activity, leghaemoglobin content of nodule, mycorrhizal colonization, dry mass of root and shoot was recorded in dual inoculated plants than plants with individual inoculation. The enhancement of nitrogen fixation of faba bean could be attributed to AMF facilitating the mobilization of certain elements such as P, Fe, K and other minerals that involve in synthesis of nitrogenase and leghaemoglobin. Thus it is

  14. Analysis of soil water repellency under different eco-geomorphological conditions in Mediterranean environments (South of Spain)

    NASA Astrophysics Data System (ADS)

    Jimenez-Donaire, Virginia; Gabarron-Galeote, Miguel A.; Martinez-Murillo, Juan F.; Ruiz-Sinoga, Jose D.

    2013-04-01

    Soil water repellency (SWR) is a soil property that reduces its water affinity. Although it has been frequently related to wildfires, different studies in recent decades have shown that repellent soils are not rare, and they are widely spread around the world under various climatic, soil and vegetation conditions, on burned and unburned soils. The research described here was carried out in two Mediterranean rangelands containing similar Mediterranean tree and shrub species but differing in soil conditions. The aim of the study was to evaluate the effects of vegetal species, pH, soil organic matter (SOM), soil water content (SWC) and prescribed fire over SWR. In June 2011, two samples from the first 5 cm of soil, one up and one downslope from plants, were collected under the dominant species of the two study areas (Nerja -NE- and Almogía -AL-), in a north-facing hillslope . In NE the selected species were Pinus halepensis (Ph), Cistus clusii (Cc), Rosmarinus officinalis (Ro), Thymus vulgaris (Tv) and Stipa tenacissima (St). In addition samples were collected in bare soil (Bs, at least 1.5m far away from the nearest shrub), under burned shrubs (Bsc) and in burned bare soil (Bbs). A controlled fire was conducted in April 2011. In AL the selected species were Quercus suber (Qs), Cistus monspeliensis (Cm) and Cistus albidus (Ca). The results indicate: i) SWR is a common phenomenon in Mediterranean environments, in acid as well as in alkaline soils, but with a great variability in every study area depending on the vegetal species (Ro and Qs) were those more repellent to water; ii) OM seems to be a more influential factor over soil water repellency than acidity, which only was found a controlling factor for alkaline soils; iii climate and vegetation type, influencing SOM leading to hydrophobic conditions, are more key factors controlling SWR than bedrock characteristics; iv) SWC threshold for water repellency to be disappeared were not clearly stated independently of

  15. Kinetics of the alkaline hydrolysis of important nitroaromatic co-contaminants of 2,4,6-trinitrotoluene in highly contaminated soils.

    PubMed

    Emmrich, M

    2001-03-01

    Until this day, large amounts of TNT and related nitroaromatic compounds are found in soils. To obtain basic data for alkaline hydrolysis of these compounds as a novel remediation technology for contaminated soils, we investigated two soils (HTNT2, ELBP2) from two former ammunition plants in Germany. Hydrolysis was performed at pH 11 and pH 12 by addition of Ca(OH)2. During treatment at pH 12 the TNT content dropped to almost zero, and the content of the aminodinitrotoluenes (2A-4,6DNT, 4A-2,6DNT) and the 2,4-dinitrotoluene (2,4-DNT) decreased by about 75% (only HTNT2) and 63%, respectively. The experimental data were described using a pseudo-first-order kinetic. Furthermore, an increase of 2,6-DNT and trinitrobenzene (TNB) as well as in one case also of TNT was initially noted in addition to hydrolysis, leading temporarily to an increase of their total amounts of up to 147%, 986%, and 122%, respectively. The results demonstrate that alkaline hydrolysis is difficult when nitroaromatics except TNT represent the major contaminants. However, regarding 2,6-DNT and TNB higher reduction rates than calculated were actually achieved by alkaline hydrolysis. In the case that TNT is the only contaminant or if it is accompanied by certain lower concentrated nitroaromatics alkaline hydrolysis is a valuable remediation technology, especially for soils that are highly contaminated.

  16. Butachlor degradation in tropical soils: effect of application rate, biotic-abiotic interactions and soil conditions.

    PubMed

    Pal, R; Das, P; Chakrabarti, K; Chakraborty, A; Chowdhury, A

    2006-01-01

    The degradative characteristics of butachlor (N-Butoxymethyl-2-chloro-2',6'-diethyla- cetanilide) were studied under controlled laboratory conditions in clay loam alluvial (AL) soil (Typic udifluvent) and coastal saline (CS) soil (Typic endoaquept) from rice cultivated fields. The application rates included field rate (FR), 2-times FR (2FR) and 10-times FR (10FR). The incubation study was carried out at 30 degrees C with and without decomposed cow manure (DCM) at 60% of maximum water holding capacity (WHC) and waterlogged soil condition. The half-life values depended on the soil types and initial concentrations of butachlor. Butachlor degraded faster in AL soil and in soil amended with DCM under waterlogged condition. Microbial degradation is the major avenue of butachlor degradation from soils.

  17. Nitroglycerin degradation mediated by soil organic carbon under aerobic conditions.

    PubMed

    Bordeleau, Geneviève; Martel, Richard; Bamba, Abraham N'Valoua; Blais, Jean-François; Ampleman, Guy; Thiboutot, Sonia

    2014-10-01

    The presence of nitroglycerin (NG) has been reported in shallow soils and pore water of several military training ranges. In this context, NG concentrations can be reduced through various natural attenuation processes, but these have not been thoroughly documented. This study aimed at investigating the role of soil organic matter (SOM) in the natural attenuation of NG, under aerobic conditions typical of shallow soils. The role of SOM in NG degradation has already been documented under anoxic conditions, and was attributed to SOM-mediated electron transfer involving different reducing agents. However, unsaturated soils are usually well-oxygenated, and it was not clear whether SOM could participate in NG degradation under these conditions. Our results from batch- and column-type experiments clearly demonstrate that in presence of dissolved organic matter (DOM) leached from a natural soil, partial NG degradation can be achieved. In presence of particulate organic matter (POM) from the same soil, complete NG degradation was achieved. Furthermore, POM caused rapid sorption of NG, which should result in NG retention in the organic matter-rich shallow horizons of the soil profile, thus promoting degradation. Based on degradation products, the reaction pathway appears to be reductive, in spite of the aerobic conditions. The relatively rapid reaction rates suggest that this process could significantly participate in the natural attenuation of NG, both on military training ranges and in contaminated soil at production facilities.

  18. Remediation of PAHs in a saline-alkaline soil amended with wastewater sludge and the effect on dynamics of C and N.

    PubMed

    Fernández-Luqueño, F; Marsch, R; Espinosa-Victoria, D; Thalasso, F; Hidalgo Lara, M E; Munive, A; Luna-Guido, M L; Dendooven, L

    2008-08-25

    Contamination of soil with hydrocarbons occurs frequently and organic material, such as sludge, is often applied to accelerate their dissipation. Little is known, however, how sludge characteristics affect removal of polycyclic aromatic hydrocarbons (PAHs) from alkaline-saline soil. Soil of the former lake Texcoco with pH 9 and electrolytic conductivity 7 dS m(-1) was contaminated with phenanthrene and anthracene and amended with sludge, sterilized sludge, sludge adjusted to maintain pH in contaminated soil or glucose plus an inorganic N and P source while emission of CO2 and concentrations of NH4+, NO3-, NO2-, extractable P, phenanthrene and anthracene were monitored in an aerobic incubation experiment of 112 days. An agricultural soil from Acolman treated in the same way served as control. Contaminating the Texcoco soil increased emission of CO2 significantly, but not in the Acolman soil. After 112 days, the largest concentration of anthracene and phenanthrene was found in the Acolman soil added with glucose and the lowest in the sludge-amended soil. The largest concentration of anthracene in the Texcoco soil was found in soil added with sterile sludge and the lowest in the sludge-amended soil. The largest concentration of phenanthrene in the Texcoco soil was found in the glucose-amended soil and the lowest in the sludge-amended soil. It was found that addition of sludge removed more phenanthrene, but not anthracene from soil compared to the unamended contaminated soil, glucose inhibited dissipation of PAHs while microorganisms in the sludge contributed to their removal, and adjustment of soil pH had no effect. Organic material can be used to accelerate removal of hydrocarbons from soil, but the effect is controlled by soil type, contaminant and organic material characteristics. PMID:18538824

  19. Remediation of PAHs in a saline-alkaline soil amended with wastewater sludge and the effect on dynamics of C and N.

    PubMed

    Fernández-Luqueño, F; Marsch, R; Espinosa-Victoria, D; Thalasso, F; Hidalgo Lara, M E; Munive, A; Luna-Guido, M L; Dendooven, L

    2008-08-25

    Contamination of soil with hydrocarbons occurs frequently and organic material, such as sludge, is often applied to accelerate their dissipation. Little is known, however, how sludge characteristics affect removal of polycyclic aromatic hydrocarbons (PAHs) from alkaline-saline soil. Soil of the former lake Texcoco with pH 9 and electrolytic conductivity 7 dS m(-1) was contaminated with phenanthrene and anthracene and amended with sludge, sterilized sludge, sludge adjusted to maintain pH in contaminated soil or glucose plus an inorganic N and P source while emission of CO2 and concentrations of NH4+, NO3-, NO2-, extractable P, phenanthrene and anthracene were monitored in an aerobic incubation experiment of 112 days. An agricultural soil from Acolman treated in the same way served as control. Contaminating the Texcoco soil increased emission of CO2 significantly, but not in the Acolman soil. After 112 days, the largest concentration of anthracene and phenanthrene was found in the Acolman soil added with glucose and the lowest in the sludge-amended soil. The largest concentration of anthracene in the Texcoco soil was found in soil added with sterile sludge and the lowest in the sludge-amended soil. The largest concentration of phenanthrene in the Texcoco soil was found in the glucose-amended soil and the lowest in the sludge-amended soil. It was found that addition of sludge removed more phenanthrene, but not anthracene from soil compared to the unamended contaminated soil, glucose inhibited dissipation of PAHs while microorganisms in the sludge contributed to their removal, and adjustment of soil pH had no effect. Organic material can be used to accelerate removal of hydrocarbons from soil, but the effect is controlled by soil type, contaminant and organic material characteristics.

  20. Effects of alkaline pretreatments and acid extraction conditions on the acid-soluble collagen from grass carp (Ctenopharyngodon idella) skin.

    PubMed

    Liu, Dasong; Wei, Guanmian; Li, Tiancheng; Hu, Jinhua; Lu, Naiyan; Regenstein, Joe M; Zhou, Peng

    2015-04-01

    This study investigated the effects of alkaline pretreatments and acid extraction conditions on the production of acid-soluble collagen (ASC) from grass carp skin. For alkaline pretreatment, 0.05 and 0.1M NaOH removed non-collagenous proteins without significant loss of ASC at 4, 10, 15 and 20 °C; while 0.2 and 0.5M NaOH caused significant loss of ASC, and 0.5M NaOH caused structural modification of ASC at 15 and 20 °C. For acid extraction at 4, 10, 15 and 20 °C, ASC was partly extracted by 0.1 and 0.2M acetic acid, while 0.5 and 1.0M acetic acid resulted in almost complete extraction. The processing conditions involving 0.05-0.1M NaOH for pretreatment, 0.5M acetic acid for extraction and 4-20 °C for both pretreatment and extraction, produced ASC with the structural integrity being well maintained and hence were recommended to prepare ASC from grass carp skin in practical application.

  1. Repeated annual paper mill and alkaline residuals application affects soil metal fractions.

    PubMed

    Gagnon, Bernard; Robichaud, Annie; Ziadi, Noura; Karam, Antoine

    2014-03-01

    The application of industrial residuals in agriculture may raise concerns about soil and crop metal accumulation. A complete study using a fractionation scheme would reveal build-up in metal pools occurring after material addition and predict the transformation of metals in soil between the different forms and potential metal release into the environment. An experimental study was conducted from 2000 to 2008 on a loamy soil at Yamachiche, Quebec, Canada, to evaluate the effects of repeated annual addition of combined paper mill biosolids when applied alone or with several liming by-products on soil Cu, Zn, and Cd fractions. Wet paper mill biosolids at 0, 30, 60, or 90 Mg ha and calcitic lime, lime mud, or wood ash, each at 3 Mg ha with 30 Mg paper mill biosolids ha, were surface applied after seeding. The soils were sampled after 6 (soybean [ (L.) Merr.]) and 9 [corn ( L.)] crop years and analyzed using the Tessier fractionation procedure. Results indicated that biosolids addition increased exchangeable Zn and Cd, carbonate-bound Cd, Fe-Mn oxide-bound Zn and Cd, organically bound Cu and Zn, and total Zn and Cd fractions but decreased Fe-Mn oxide-bound Cu in the uppermost 30-cm layer. With liming by-products, there was a shift from exchangeable to carbonate-bound forms. Even with very small metals addition, paper mill and liming materials increased the mobility of soil Zn and Cd after 9 yr of application, and this metal redistribution resulted into higher crop grain concentrations. PMID:25602653

  2. Stacking and determination of phenazine-1-carboxylic acid with low pKa in soil via moving reaction boundary formed by alkaline and double acidic buffers in capillary electrophoresis.

    PubMed

    Sun, Chong; Yang, Xiao-Di; Fan, Liu-Yin; Zhang, Wei; Xu, Yu-Quan; Cao, Cheng-Xi

    2011-04-01

    As shown herein, a normal moving reaction boundary (MRB) formed by an alkaline buffer and a single acidic buffer had poor stacking to the new important plant growth promoter of phenazine-1-carboxylic acid (PCA) in soil due to the leak induced by its low pK(a). To stack the PCA with low pK(a) efficiently, a novel stacking system of MRB was developed, which was formed by an alkaline buffer and double acidic buffers (viz., acidic sample and blank buffers). With the novel system, the PCA leaking into the blank buffer from the sample buffer could be well stacked by the prolonged MRB formed between the alkaline buffer and blank buffer. The relevant mechanism of stacking was discussed briefly. The stacking system, coupled with sample pretreatment, could achieve a 214-fold increase of PCA sensitivity under the optimal conditions (15 mM (pH 11.5) Gly-NaOH as the alkaline buffer, 15 mM (pH 3.0) Gly-HCl-acetonitrile (20%, v/v) as the acidic sample buffer, 15 mM (pH 3.0) Gly-HCl as the blank buffer, 3 min 13 mbar injection of double acidic buffers, benzoic acid as the internal standard, 75 μm i.d. × 53 cm (44 cm effective length) capillary, 25 kV and 248 nm). The limit of detection of PCA in soil was decreased to 17 ng/g, the intra-day and inter-day precision values (expressed as relative standard deviations) were 3.17-4.24% and 4.17-4.87%, respectively, and the recoveries of PCA at three concentration levels changed from 52.20% to 102.61%. The developed method could be used for the detection of PCA in soil at trace level.

  3. Enhanced biodegradation of methoxychlor in soil under sequential environmental conditions.

    PubMed Central

    Fogel, S; Lancione, R L; Sewall, A E

    1982-01-01

    Ring-U-[14C]methoxychlor [1,1-bis(p-methoxyphenyl)-2,2,2-trichloroethane] was incubated in soil under aerobic and anaerobic conditions. Primary degradation of methoxychlor occurred under anaerobic conditions, but not under aerobic conditions, after 3 months of incubation. Analysis of soil extracts, using gas chromatography, demonstrated that only 10% of the compound remained at initial concentrations of 10 and 100 ppm (wt/wt) of methoxychlor. Evidence is presented that a dechlorination reaction was responsible for primary degradation of methoxychlor. Analysis of soils treated with 100 ppm of methoxychlor in the presence of 2% HgCl2 showed that 100% of the compound remained after 3 months, indicating that degradation in the unpoisoned flasks was biologically mediated. Methanogenic organisms, however, are probably not involved, as strong inhibition of methane production was observed in all soils treated with methoxychlor. During the 3-month incubation period, little or no evaluation of 14CO2 or 14CH4 occurred under either aerobic or anaerobic conditions. Cometabolic processes may be responsible for the extensive molecular changes which occurred with methoxychlor because the rate of its disappearance from soil was observed to level off after exhaustion of soil organic matter. After this incubation period, soils previously incubated under anaerobic conditions were converted to aerobic conditions. The rates of 14CO2 evolution from soils exposed to anaerobic and aerobic sequences of environments ranged from 10- to 70-fold greater than that observed for soils exposed solely to an aerobic environment. PMID:7125645

  4. ECOSYSTEM RESTORATION ON METAL-TOXIC SOILS USING BIOSOLIDS AND ALKALINE BYPRODUCTS

    EPA Science Inventory

    Soils in many locations are mineralized or were contaminated by industry (e.g. mine wastes; smelter emissions). Zn-Pb-Ag-Cu ores often caused severe Zn phytotoxicity which killed vegetation and prevented normal colonization; severe N and P infertility also contributed to difficul...

  5. ECOSYSTEM RESOTRATION ON METAL-TOXIC SOILS USING BIOSOLIDS AND ALKALINE BYPRODUCTS (ABSTRACT)

    EPA Science Inventory

    Soils in many locations are mineralized or were contaminated by industry (e.g. mine wastes; smelter emissions). Zn-Pb-Ag-Cu ores often caused severe Zn phytotoxicity which killed vegetation and prevented normal colonization; severe N and P infertility also contributed to difficul...

  6. Effectiveness of recovered magnesium phosphates as fertilizers in neutral and slightly alkaline soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Magnesium phosphates such as struvite (MgNH4PO4x6H2O) can be recovered from municipal, industrial and agricultural wastewaters. However, minimal research has been conducted on the beneficial reuse of these recovered products; conducted research has focused on low pH soils. This study determined wh...

  7. Draft Genome Sequence of Jeotgalibacillus soli DSM 23228, a Bacterium Isolated from Alkaline Sandy Soil

    PubMed Central

    Chan, Kok-Gan; Yaakop, Amira Suriaty; Chan, Chia Sing; Ee, Robson; Tan, Wen-Si; Gan, Han Ming

    2015-01-01

    Jeotgalibacillus soli, a bacterium capable of degrading N-acyl homoserine lactone, was isolated from a soil sample in Portugal. J. soli constitutes the only Jeotgalibacillus species isolated from a non-marine source. Here, the draft genome, several interesting glycosyl hydrolases, and its putative N-acyl homoserine lactonases are presented. PMID:25999554

  8. Effect of different carbon sources on decolourisation of an industrial textile dye under alkaline-saline conditions.

    PubMed

    Ottoni, Cristiane; Lima, Luis; Santos, Cledir; Lima, Nelson

    2014-01-01

    White-rot fungal strains of Trametes versicolor and Phanerochaete chrysosporium were selected to study the decolourisation of the textile dye, Reactive Black 5, under alkaline-saline conditions. Free and immobilised T. versicolor cells showed 100 % decolourisation in the growth medium supplemented with 15 g l(-1) NaCl, pH 9.5 at 30 °C in liquid batch culture. Continuous culture experiments were performed in a fixed-bed reactor using free and immobilised T. versicolor cells and allowed 85-100 % dye decolourisation. The immobilisation conditions for the biomass and the additional supply of carbon sources improved the decolourisation performance during a long-term trial of 40 days. Lignin peroxidase, laccase and glyoxal oxidase activities were detected during the experiments. The laccase activity varied depending on carbon source utilized and glycerol-enhanced laccase activity compared to sucrose during extended growth.

  9. Organic and inorganic amendments affect soil concentration and accumulation of cadmium and lead in wheat in calcareous alkaline soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Irrigation with untreated effluent in periurban agriculture could result in accumulation and bioconcentrations of cadmium (Cd) and lead (Pb). Different amendments were used to investigate their effect on availability, concentration, and uptake of metals by wheat in texturally different soils. Crop w...

  10. Isolation and fractionation of soil humin using alkaline urea and dimethylsulphoxide plus sulphuric acid

    NASA Astrophysics Data System (ADS)

    Song, Guixue; Hayes, Michael H. B.; Novotny, Etelvino H.; Simpson, Andre J.

    2011-01-01

    Humin, the most recalcitrant and abundant organic fraction of soils and of sediments, is a significant contributor to the stable carbon pool in soils and is important for the global carbon budget. It has significant resistance to transformations by microorganisms. Based on the classical operational definition, humin can include any humic-type substance that is not soluble in water at any pH. We demonstrate in this study how sequential exhaustive extractions with 0.1 M sodium hydroxide (NaOH) + 6 M urea, followed by dimethylsulphoxide (DMSO) + 6% ( v/ v) sulphuric acid (H2SO4) solvent systems, can extract 70-80% of the residual materials remaining after prior exhaustive extractions in neutral and aqueous basic media. Solid-state 13C NMR spectra have shown that the components isolated in the base + urea system were compositionally similar to the humic and fulvic acid fractions isolated at pH 12.6 in the aqueous media. The NMR spectra indicated that the major components isolated in the DMSO + H2SO4 medium had aliphatic hydrocarbon associated with carboxyl functionalities and with lesser amounts of carbohydrate and peptide and minor amounts of lignin-derived components. The major components will have significant contributions from long-chain fatty acids, waxes, to cuticular materials. The isolates in the DMSO + H2SO4 medium were compositionally similar to the organic components that resisted solvation and remained associated with the soil clays. It is concluded that the base + urea system released humic and fulvic acids held by hydrogen bonding or by entrapment within the humin matrix. The recalcitrant humin materials extracted in DMSO + H2SO4 are largely biological molecules (from plants and the soil microbial population) that are likely to be protected from degradation by their hydrophobic moieties and by sorption on the soil clays. Thus, the major components of humin do not satisfy the classical definitions for humic substances which emphasise that these arise from

  11. Recent Alkaline Lakes: Clues to Understanding the Evolution of Early Planetary Alkaline Oceans and Biogenesis

    NASA Astrophysics Data System (ADS)

    Kempe, S.; Hartmann, J.; Kazmierczak, J.

    2008-09-01

    Abstract New models suggest that terrestrial weathering consumes 0.26GtC/a (72% silicate-, 28% carbonateweathering), equivalent to a loss of one atmospheric C content every 3700a. Rapid weathering leads in volcanic areas to alkaline conditions, illustrated by the crater lake of Niuafo`ou/Tonga and Lake Van/Turkey, the largest soda lake on Earth. Alkaline conditions cause high CaCO3 supersaturation, permineralization of algal mats and growth of stromatolites. Alkaline conditions can nearly depress free [Ca2+] to levels necessary for proteins to function. Therefore early oceans on Earth (and possibly on Mars) should have been alkaline (i.e. "Soda Oceans"). Recent findings of MgSO4 in top soils on Mars may be misleading about the early history of martian oceans.

  12. Effect of chelating agent concentration in alkaline Cu CMP process under the condition of different applied pressures

    NASA Astrophysics Data System (ADS)

    Haobo, Yuan; Yuling, Liu; Mengting, Jiang; Weijuan, Liu; Guodong, Chen

    2014-11-01

    We propose the action mechanism of Cu chemical mechanical planarization (CMP) in an alkaline solution. Meanwhile, the effect of abrasive mass fraction on the copper removal rate and within wafer non-uniformity (WIWNU) have been researched. In addition, we have also investigated the synergistic effect between the applied pressure and the FA/O chelating agent on the copper removal rate and WIWNU in the CMP process. Based on the experimental results, we chose several concentrations of the FA/O chelating agent, which added in the slurry can obtain a relatively high removal rate and a low WIWNU after polishing, to investigate the planarization performance of the copper slurry under different applied pressure conditions. The results demonstrate that the copper removal rate can reach 6125 Å/min when the abrasive concentration is 3 wt.%. From the planarization experimental results, we can see that the residual step height is 562 Å after excessive copper of the wafer surface is eliminated. It denotes that a good polishing result is acquired when the FA/O chelating agent concentration and applied pressure are fixed at 3 vol% and 1 psi, respectively. All the results set forth here are very valuable for the research and development of alkaline slurry.

  13. Conservation tillage and traffic effects on soil condition

    SciTech Connect

    Raper, R.L.; Reeves, D.W.; Burt, E.C.; Torbert, H.A.

    1994-05-01

    The soil condition resulting from a five-year cotton-wheat double cropping experiment in a sandy loam Coastal Plain soil was investigated using intensive measurements of cone index and dry bulk density. Four tillage treatments including a strip-till (no surface tillage with in-row subsoiling) conservation tillage practice were analyzed. The traffic was controlled in the experimental plots with the USDA-ARS Wide-Frame Tractive Vehicle. Besides the environmental benefits of maintaining the surface residue, the strip-till treatment decreased cone index directly beneath the row, decreased surface bulk density, increased surface moisture content, decreased energy usage, and increased yields. Controlled traffic was beneficial only when in-row subsoiling was not used as an annual tillage treatment. Although differences in soil condition were seen beneath the row middles where traffic occurred, this did not affect the soil condition directly beneath the row. 16 refs., 7 figs., 2 tabs.

  14. Occurrence of salt, pH, and temperature-tolerant, phosphate-solubilizing bacteria in alkaline soils

    PubMed

    Johri; Surange; Nautiyal

    1999-08-01

    An ecological survey was conducted to characterize 4800 bacterial strains isolated from the root-free soil, rhizosphere, and rhizoplane of Prosopis juliflora growing in alkaline soils. Of the 4800 bacteria, 857 strains were able to solubilize phosphate on plates. The incidence of phosphate-solubilizing bacteria (PSB) in the rhizoplane was highest, followed by rhizosphere and root-free soil. Eighteen bacterial strains out of 857 PSB were able to produce halo at 30 degrees C in a plate assay in the presence of 5% salt (NaCl) and solubilize tricalcium phosphate in National Botanical Research Institute's phosphate growth medium (NBRIP) broth, in the presence of various salts, pHs, and temperatures. Among the various bacteria tested, NBRI4 and NBRI7 did not produced halo in a plate assay at 30 degrees C in the absence of salt. Contrary to indirect measurement of phosphate solubilization by plate assay, the direct measurement of phosphate solubilization in NBRIP broth assay always resulted in reliable results. The phosphate solubilization ability of NBRI4 was higher than in the control in the presence of salts (NaCl, CaCl2, and KCl) at 30 degrees C. Phosphate solubilization further increased in the presence of salts at 37 degrees C as compared with 30 degrees C. At 37 degrees C, CaCl2 reduced phosphate solubilization ability of NBRI4 compared with the control. The results indicated the role of calcium salt in the phosphate solubilization ability of NBRI4.http://link.springer-ny. com/link/service/journals/00284/bibs/39n2p89.html PMID:10398833

  15. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    PubMed

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P < 0.01) linear regression function, which suggested that invertase was a good indicator of the magnitude of soil microbial respiration.

  16. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    PubMed

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P < 0.01) linear regression function, which suggested that invertase was a good indicator of the magnitude of soil microbial respiration. PMID:26164932

  17. Extension of laboratory-measured soil spectra to field conditions

    NASA Technical Reports Server (NTRS)

    Stoner, E. R.; Baumgardner, M. F.; Weismiller, R. A.; Biehl, L. L.; Robinson, B. F.

    1982-01-01

    Spectral responses of two glaciated soils, Chalmers silty clay loam and Fincastle silt loam, formed under prairie grass and forest vegetation, respectively, were measured in the laboratory under controlled moisture equilibria using an Exotech Model 20C spectroradiometer to obtain spectral data in the laboratory under artificial illumination. The same spectroradiometer was used outdoors under solar illumination to obtain spectral response from dry and moistened field plots with and without corn residue cover, representing the two different soils. Results indicate that laboratory-measured spectra of moist soil are directly proportional to the spectral response of that same field-measured moist bare soil over the 0.52 micrometer to 1.75 micrometer wavelength range. The magnitudes of difference in spectral response between identically treated Chalmers and Fincastle soils are greatest in the 0.6 micrometers to 0.8 micrometer transition region between the visible and near infrared, regardless of field condition or laboratory preparation studied.

  18. Enhancing uranium uptake by amidoxime adsorbent in seawater: An investigation for optimum alkaline conditioning parameters

    DOE PAGES

    Das, Sadananda; Tsouris, Costas; Zhang, Chenxi; Brown, Suree; Janke, Christopher James; Mayes, Richard T.; Kuo, Li -Jung; Gill, Gary; Dai, Sheng; Kim, J.; et al

    2015-09-07

    A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 °C). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration ofmore » ~7–8 ppm and pH 8. Fourier transform infrared spectroscopy and solid-state NMR analyses indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 °C resulted in an increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. The scanning electron microscopy showed that long

  19. Enhancing uranium uptake by amidoxime adsorbent in seawater: An investigation for optimum alkaline conditioning parameters

    SciTech Connect

    Das, Sadananda; Tsouris, Costas; Zhang, Chenxi; Brown, Suree; Janke, Christopher James; Mayes, Richard T.; Kuo, Li -Jung; Gill, Gary; Dai, Sheng; Kim, J.; Oyola, Y.; Wood, J. R.

    2015-09-07

    A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 °C). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration of ~7–8 ppm and pH 8. Fourier transform infrared spectroscopy and solid-state NMR analyses indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 °C resulted in an increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. The scanning electron microscopy showed that long conditioning

  20. Alkalinity to calcium flux ratios for corals and coral reef communities: variances between isolated and community conditions

    PubMed Central

    Jokiel, Paul L.

    2014-01-01

    Calcification in reef corals and coral reefs is widely measured using the alkalinity depletion method which is based on the fact that two protons are produced for every mole of CaCO3 precipitated. This assumption was tested by measuring the total alkalinity (TA) flux and Ca2+ flux of isolated components (corals, alga, sediment and plankton) in reference to that of a mixed-community. Experiments were conducted in a flume under natural conditions of sunlight, nutrients, plankton and organic matter. A realistic hydrodynamic regime was provided. Groups of corals were run separately and in conjunction with the other reef components in a mixed-community. The TA flux to Ca2+ flux ratio (ΔTA: ΔCa2+) was consistently higher in the coral-only run (2.06 ± 0.19) than in the mixed-community run (1.60 ± 0.14, p-value = 0.011). The pH was higher and more stable in the mixed-community run (7.94 ± 0.03 vs. 7.52 ± 0.07, p-value = 3 × 10−5). Aragonite saturation state (Ωarag) was also higher in the mixed-community run (2.51 ± 0.2 vs. 1.12 ± 0.14, p-value = 2 × 10−6). The sediment-only run revealed that sediment is the source of TA that can account for the lower ΔTA: ΔCa2+ ratio in the mixed-community run. The macroalgae-only run showed that algae were responsible for the increased pH in the mixed-community run. Corals growing in a mixed-community will experience an environment that is more favorable to calcification (higher daytime pH due to algae photosynthesis, additional TA and inorganic carbon from sediments, higher Ωarag). A paradox is that the alkalinity depletion method will yield a lower net calcification for a mixed-community versus a coral-only community due to TA recycling, even though the corals may be calcifying at a higher rate due to a more optimal environment. PMID:24688834

  1. Arsenic in an Alkaline AMD Treatment Sludge: Characterization and Stability Under Prolonged Anoxic Conditions

    SciTech Connect

    Beauchemin, S.; Fiset, J; Poirier, G; Ablett, J

    2010-01-01

    Lime treatment of acid mine drainage (AMD) generates large volumes of neutralization sludge that are often stored under water covers. The sludge consists mainly of calcite, gypsum and a widespread ferrihydrite-like Fe phase with several associated species of metal(loid) contaminants. The long-term stability of metal(loid)s in this chemically ill-defined material remains unknown. In this study, the stability and speciation of As in AMD sludge subjected to prolonged anoxic conditions is determined. The total As concentration in the sludge is 300 mg kg{sup -1}. In the laboratory, three distinct water cover treatments were imposed on the sludge to induce different redox conditions (100%N{sub 2}, 100%N{sub 2} + glucose, 95%N{sub 2}:5%H{sub 2}). These treatments were compared against a control of oxidized, water-saturated sludge. Electron micro-probe (EMP) analysis and spatially resolved synchrotron X-ray fluorescence (SXRF) results indicate that As is dominantly associated with Fe in the sludge. In all treatments and throughout the experiment, measured concentrations of dissolved As were less than 5 {micro}g L{sup -1}. Dissolved Mn concentration in the N{sub 2} + glucose treatment increased significantly compared to other treatments. Manganese and As K-edge X-ray absorption near edge structure spectroscopy (XANES) analyses showed that Mn was the redox-active element in the solid-phase, while As was stable. Arsenic(V) was still the dominant species in all water-covered sludges after 9 months of anoxic treatments. In contrast, Mn(IV) in the original sludge was partially reduced into Mn(II) in all water-covered sludges. The effect was most pronounced in the N{sub 2} + glucose treatment, suggesting microbial reduction. Micro-scale SXRF and XANES analysis of the treated sludge showed that Mn(II) accumulated in areas already enriched in Fe and As. Overall, the study shows that AMD sludges remain stable under prolonged anoxic conditions. External sources of chemical reductants

  2. Multi-technique approach for qualitative and quantitative characterization of furazidin degradation kinetics under alkaline conditions.

    PubMed

    Bērziņš, Kārlis; Kons, Artis; Grante, Ilze; Dzabijeva, Diana; Nakurte, Ilva; Actiņš, Andris

    2016-09-10

    Degradation of drug furazidin was studied under different conditions of environmental pH (11-13) and temperature (30-60°C). The novel approach of hybrid hard- and soft-multivariate curve resolution-alternating least squares (HS-MCR-ALS) method was applied to UV-vis spectral data to determine a valid kinetic model and kinetic parameters of the degradation process. The system was found to be comprised of three main species and best characterized by two consecutive first-order reactions. Furazidin degradation rate was found to be highly dependent on the applied environmental conditions, showing more prominent differences between both degradation steps towards higher pH and temperature. Complimentary qualitative analysis of the degradation process was carried out using HPLC-DAD-TOF-MS. Based on the obtained chromatographic and mass spectrometric results, as well as additional computational analysis of the species (theoretical UV-vis spectra calculations utilizing TD-DFT methodology), the operating degradation mechanism was proposed to include formation of a 5-hydroxyfuran derivative, followed by complete hydrolysis of furazidin hydantoin ring.

  3. Preliminary study of the refaunation of alkaline shale coal surface mine spoil by soil arthropods

    SciTech Connect

    Cross, E.A.; Wilman, J.M.

    1982-12-01

    Soil sampling stations were laid out on (largely) untopsoiled shale surface mine spoil in 1979. Stations were located on spoil graded in 1978-1979, in ungraded spoil cast in 1972 and aerially seeded in 1973, and in adjacent off-mine woods and an old field. Additional stations were added in 1982 on spoil graded only 3.5 weeks - 3 months prior to sampling. Stations were located to include important variables typical of the mine. Of 17 classes-orders of arthropods recovered from all sites, only Acari (78-99% of total individuals) and Collembola (2-12%) were consistently widespread and numerous, and only Acari were important in the youngest spoils. A total of 69 mite families - superfamilies - were identified during the course of the study. Low-moderate mite populations were found in bare shale spoil graded only 3.5 weeks - 3 months prior to sampling, these distributed among 4 families. Samples from 1978-79 spoil contained 13 families 3-7 months after grading and 2 years later were comparable to off-mine sites both in numbers of individuals and number of families. Spoil from 1973 was comparable to off-mine sites in these 2 respects when first sampled. Earliest pioneer species were 3 (presumably) microherbivores, these remaining dominant for several years. Predatory mites appeared early and were well established less than a year after grading. Saprovores were absent or relatively scarce in the 2 youngest spoils, but well established in the 1973 spoil at first sampling.

  4. Phytoactinopolyspora alkaliphila sp. nov., an alkaliphilic actinomycete isolated from a saline-alkaline soil.

    PubMed

    Zhang, Yong-Guang; Lu, Xin-Hua; Ding, Yan-Bo; Zhou, Xing-Kui; Li, Li; Guo, Jian-Wei; Wang, Hong-Fei; Duan, Yan-Qing; Li, Wen-Jun

    2016-05-01

    An alkaliphilic, filamentous actinomycete, designated EGI 80629T, was isolated from a soil sample of Xinjiang, north-west China. Strain EGI 80629T grew at pH 6.0-11.0 (optimum pH 9.0-10.0) and in the presence of 0-13.0 % NaCl (optimum 3.0-5.0 %). The isolate formed fragmented substrate mycelia, and aerial hyphae with short spore chains with rod-like spores. Whole-cell hydrolysates of the isolate contained ll-diaminopimelic acid as the diagnostic diamino acid, and mannose and rhamnose as diagnostic sugars. The major fatty acids identified were iso-C15 : 0, iso-C16 : 0, anteiso-C15 : 0 and iso-C17 : 0. The predominant menaquinone was MK-9(H4), while the polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two phosphatidylinositol mannosides, five unknown phospholipids, three unknown phosphoglycolipids, one unknown glycolipid, four unknown polar lipids and one unknown aminophospholipid. The G+C content of the genomic DNA was 67.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain EGI 80629T clustered with the genus Phytoactinopolyspora. The 16S rRNA gene sequence similarity between strain EGI 80629T and Phytoactinopolyspora endophytica EGI 60009T was 96.8 %. Based on morphological, chemotaxonomic and phylogenetic characteristics, strain EGI 80629T represents a novel species of the genus Phytoactinopolyspora, for which the name Phytoactinopolyspora alkaliphila sp. nov. is proposed. The type strain is EGI 80629T ( = CGMCC 4.7225T = KCTC 39701T). PMID:26920762

  5. Identification of α-amylase by random and specific mutagenesis of Texcoconibacillus texcoconensis 13CCT strain isolated from extreme alkaline-saline soil of the former Lake Texcoco (Mexico).

    PubMed

    Bello-López, Juan Manuel; Navarro-Noya, Yendi E; Gómez-Acata, Selene; Hernández-Montañez, Zahuiti; Dendooven, Luc

    2014-05-01

    The alkaline α-amylase produced by Texcoconibacillus texcoconensis 13CC(T) strain was identified by random mutagenesis and confirmed by directed mutagenesis. A transposon mutagenesis approach was taken to identify the gene responsible for the degradation of starch in T. texcoconensis 13CC(T) strain. The deduced amino acids of the amy gene had a 99% similarity with those of Bacillus selenitireducens MLS10 and 97% with those of Paenibacillus curdlanolyticus YK9. The enzyme showed a maximum activity of 131.1 U/mL at 37 °C and pH 9.5 to 10.5. In situ activity of the enzyme determined by polyacrylamide gel electrophoresis showed only one band with amylolytic activity. This is the first report of a bacterium isolated from the extreme alkaline-saline soil of the former Lake Texcoco (Mexico) with amylolytic activity in alkaline conditions while its potential as a source of amylases for the industry is discussed.

  6. Dissolution Kinetics of Meta-Torbernite under Circum-neutral to Alkaline Conditions

    SciTech Connect

    Wellman, Dawn M.; McNamara, Bruce K.; Bacon, Diana H.; Cordova, Elsa A.; Ermi, Ruby M.; Top, Laken M.

    2009-12-21

    Autunite group minerals have been identified in contaminated sediments as the long-term controlling phase of uranium. Meta-torbernite, has been identified in subsurface environments which were subjected to co-contaminant disposal practices from past nuclear weapons and fuel operations. Under these conditions the mobility of uranium in subsurface pore waters is limited by the rate of meta-torbernite dissolution; however, there are no known investigations which report the dissolution behavior of meta-torbernite. The purpose of this investigation was to conduct a series of single-pass flow-through (SPFT) tests to 1) quantify the effect of temperature (23 - 90oC) and pH (6 -10) on meta-torbernite dissolution, 2) compare the dissolution of meta-torbernite to other autunite-group minerals, and 3) evaluate the effect of aqueous phosphate on the dissolution kinetics of meta-torbernite. Results presented here illustrate meta-torbernite dissolution rates increase by ~100X over the pH interval of 6 to 10 (eta = 0.59 ± 0.07), irrespective of temperature. The power law coefficient for meta-torbernite, eta = 0.59 ± 0.07, is greater than that quantified for Ca-meta-autunite, eta = 0.42 ± 0.12. This suggests the stability of meta-torbernite is greater than that of meta-autunite, which is reflected in the predicted stability constants. The rate equation for the dissolution of meta-torbernite as a function of aqueous phosphate concentration is log rdissol (mol m-2 sec-1) = -4.7 x 10-13 + 4.1 x 10-10 [PO43-].

  7. Unification of soil feedback patterns under different evaporation conditions to improve soil differentiation over flat area

    NASA Astrophysics Data System (ADS)

    Guo, Shanxin; Zhu, A.-Xing; Meng, Lingkui; Burt, James E.; Du, Fei; Liu, Jing; Zhang, Guiming

    2016-07-01

    Detailed and accurate information on the spatial variation of soil types and soil properties are critical components of environmental research and hydrological modeling. Early studies introduced a soil feedback pattern as a promising environmental covariate to predict spatial variation over low-relief areas. However, in practice, local evaporation can have a significant influence on these patterns, making them incomparable at different locations. This study aims to solve this problem by examining the concept of transforming the dynamic patterns of soil feedback from the original time-related space to a new evaporation-related space. A study area in northeastern Illinois with large low-relief farmland was selected to examine the effectiveness of this idea. Images from MODIS in Terra for every April-May period over 12 years (2000-2011) were used to extract the soil feedback patterns. Compared to the original time-related space, the results indicate that the patterns in the new evaporation-related space tend to be more stable and more easily captured from multiple rain events regardless of local evaporation conditions. Random samples selected for soil subgroups from the SSURGO soil map show that patterns in the new space reveal a difference between different soil types. And these differences in patterns are closely related to the difference in the soil structure of the surface layer.

  8. Mathematical modeling of electrochemical remediation for soils under galvanostatic conditions.

    PubMed

    Teutli León, M M; Oropeza Guzmán, M T; González, I

    2001-01-01

    This work proposes a mathematical model for the electrochemical remediation of clayey soils based on the total volume concept for a two-phase system. The mathematical formulation was done including contributions from theories for: groundwater, membranes, porous electrodes and environmental soil chemistry. The resulting model accounts for: free and complexed species in the soil matrix and the pore solution; chemical reactions taking place on either phase and/or between phases; a dynamic soil surface charge affected by the ion content of the pore solution; and electroneutrality of the total volume. Soil surface charge was included in a modified Ohm's law (voltage gradient) and in a modified Schlög's law (convective movement). Numerical implementation was done using orthogonal collocation on finite elements for spatial derivatives, and forward finite differences for time derivatives. Visual Fortran supported by IMSL subroutines was used for computer simulation. Model predictions were successfully compared with reported experimental data. Also, an analysis of pH profiles through the soil is provided for conditions when parameters including hydrostatic head, applied current density and initial pH are modified.

  9. Enhanced dissipation of polycyclic aromatic hydrocarbons in the rhizosphere of the Athel tamarisk (Tamarix aphylla L. Karst.) grown in saline-alkaline soils of the former lake Texcoco.

    PubMed

    Betancur-Galvis, Liliana A; Carrillo, Hernando; Luna-Guido, Marco; Marsch, Rodolfo; Dendooven, Luc

    2012-09-01

    Remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated alkaline saline soil with phreatophyte or "water loving plants" was investigated by spiking soil from the former lake Texcoco with 100 mg phenanthrene (Phen) kg(-1) soil, 120 mg anthracene (Ant)kg(-1) soil and 45 mg benzo(a)pyrene (BaP) kg(-1) soil and vegetating it with Athel tamarisk (Tamarix aphylla L Karst.). The growth of the Athel tamarisk was not affected by the PAHs. In soil cultivated with Athel tamarisk, the leaching of PAHs to the 32-34 cm layer decreased 2-fold compared to the uncultivated soil. The BaP concentration decreased to 39% of the initial concentration at a distance smaller than 3 cm from the roots and to 45% at a distance larger than 3cm, but 59% remained in unvegetated soil after 240 days. Dissipation of Ant and Phen decreased with depth, but not BaP. The biodegradation of PAHs was affected by their chemical properties and increased in the presence of T. aphylla, but decreased with depth.

  10. Changes in Soil Minerology Reduce Phosphorus Mobility During Anoxic Soil Conditions

    NASA Astrophysics Data System (ADS)

    Giri, S. K.; Geohring, L. D.; Richards, B. K.; Walter, M.; Steenhuis, T. S.

    2008-05-01

    Phosphorus (P) transfer from the landscape to receiving waters is an important environmental concern because these diffuse losses may cause widespread water quality impairments which can accelerate freshwater eutrophication. Phosphorus (P) mobilization from soil to surface and subsurface flow paths is controlled by numerous factors, and thus it can vary greatly with time and landscape scale. To determine whether P mobilization during soil saturation in the landscape was caused or controlled by complexation, iron reduction or ligand exchange, experiments were carried out to better characterize the interrelationships of varying P sources with dissolved organic carbon (DOC) and soil anoxic conditions. The soil incubation experiments consisted of treatments with distilled water, 5 mM acetic acid (HAc), 0.05% humic acid (HA) and glucose (40 mM) at 26 o C under anaerobic conditions to isolate effects of the various P exchange processes. The experimental results suggest that during soil saturation, the loosely bound P, which is primarily associated with iron oxyhydroxides, was mobilized by both reduction and complexation processes. Good correlations were observed between ferrous iron (Fe+2) and DOC, and between total dissolved phosphorus (TDP) and DOC, facilitating P desorption to the soil water. The anaerobic soil conditions with different P sources also indicated that mineralization facilitated P mobility, mainly due to chelation (humics and metabolites) and as a result of the bio-reduction of iron when fresh litter and grass were present. The organic P sources which are rich in carbohydrate and cellulose and that undergo fermentation due to the action of lactate forming organisms also caused a release of P. The easily metabolizable DOC sources lead to intensive bio-reduction of soil with the release of Fe, however this did not necessarily appear to cause more TDP in the soil solution. The varying P additions in soils with water, HAc and glucose (40mm) before and after

  11. Biodegradation of a Light NAPL under Varying Soil Environmental Conditions

    NASA Astrophysics Data System (ADS)

    Yadav, B. K.; Hassanizadeh, S. M.; Kleingeld, P. J.

    2009-12-01

    To see the impact of different soil environmental conditions on LNAPL biodegradation, a series of batch, microcosm, column and 2-D tank experiments under controlled conditions have been planned. Microcosms along with batch experiments have been designed for five different moisture contents ranging from residual to saturated, and under varying temperature condition. The batches are being used for two saturated soils containing toluene. For the unsaturated cases, fifteen microcosms are designed to mimic natural conditions more closely. The microcosms consist of a transparent outer column and an air permeable, but watertight, inner tube comprised of toluene phobic material. The space between the outer column and the inner porous tube is filled with a soil having a particular moisture content with a known amount of toluene. The inner porous tube is filled with air at atmospheric pressure, providing sufficient oxygen for the degradation of considered light NAPL. A special sampling mechanism has been fabricated to enable airtight soil sampling. Four columns have been designed for studying the impact of water table fluctuation on the LNAPL fate and transport in variably-saturated soil. Water table in two columns will be static and remaining two will be subjected to a fluctuation. Finally a 2-D tank setup, made of a steel box and a glass cover, has been refurbished for bioremediation process of LNAPL from start to finish. The main body is constructed of one piece of 1.5 mm thick stainless steel formed into a box with inner dimensions of 200cm-long x 94cm-high x 4cm-deep. The front cover is made of glass wall having 19-mm thickness. The soil is going to be packed between the two walls. The groundwater will be flowing horizontally from left to right and the water table level in the tank will be controlled by two end chambers. The chambers are separated from the soil by a fine meshed stainless steel sheet. The spatial and the temporal distributions of the LNAPL and its

  12. Strong-Coupled Cobalt Borate Nanosheets/Graphene Hybrid as Electrocatalyst for Water Oxidation Under Both Alkaline and Neutral Conditions.

    PubMed

    Chen, Pengzuo; Xu, Kun; Zhou, Tianpei; Tong, Yun; Wu, Junchi; Cheng, Han; Lu, Xiuli; Ding, Hui; Wu, Changzheng; Xie, Yi

    2016-02-12

    Developing highly active catalysts for the oxygen evolution reaction (OER) is of paramount importance for designing various renewable energy storage and conversion devices. Herein, we report the synthesis of a category of Co-Pi analogue, namely cobalt-based borate (Co-Bi ) ultrathin nanosheets/graphene hybrid by a room-temperature synthesis approach. Benefiting from the high surface active sites exposure yield, enhanced electron transfer capacity, and strong synergetic coupled effect, this Co-Bi NS/G hybrid shows high catalytic activity with current density of 10 mA cm(-2) at overpotential of 290 mV and Tafel slope of 53 mV dec(-1) in alkaline medium. Moreover, Co-Bi NS/G electrocatalysts also exhibit promising performance under neutral conditions, with a low onset potential of 235 mV and high current density of 14.4 mA cm(-2) at 1.8 V, which is the best OER performance among well-developed Co-based OER electrocatalysts to date. Our finding paves a way to develop highly active OER electrocatalysts. PMID:26757358

  13. Leaf structure vs. nutrient relationships vary with soil conditions in temperate shrubs and trees

    NASA Astrophysics Data System (ADS)

    Niinemets, Ülo; Kull, Kalevi

    2003-09-01

    Often there are significant positive interspecific relationships between leaf area per unit dry mass (SLA) and foliar phosphorus and nitrogen concentrations ([P] and [N]). Most of these studies have been conducted on moderately acidic soils, and little is known of the generality of these relations as potentially affected by soil characteristics. We investigated foliage mineral composition in relation to leaf structure in a wooded meadow on calcareous alkaline soil, in a bog on strongly acidic soil, and in a flood plain on moderately acidic soil. Foliar nutrient contents and fertilization experiments indicated that foliage physiological activity was co-limited by both P and N availabilities in the wooded meadow, by P in the bog, and by N in the flood plain. In the wooded meadow and in the bog, there were positive relationships between SLA and P concentration ([P]), and no relationship between SLA and nitrogen concentration [N]. Given that the fraction of support tissues generally increases with decreasing SLA, the requirement for mineral nutrients is lower at low SLA. Thus, these contrasting relations between mineral nutrients and SLA suggest that P was distributed in a more "optimal" manner among the leaves with varying structure than N in P-limited communities. In the flood plain, SLA was positively related to both [P] and [N], possibly manifesting a strategy to cope with N limitations by enhancing N turnover, and accordingly, greater P requirement for nucleic acid formation in N-limited soils. Total variation in foliar structural and chemical characteristics was similar in all sites, and was mainly determined by variation among the species. Part of this variability was explained by life form and plant size. [P] was higher in trees than in shrubs, and [P] and P/N ratio increased with increasing total plant height, indicating that P nutrition was improved relative to N nutrition with increasing plant size. Since the capture of less mobile soil elements such as P is

  14. Soil microbial respiration from various microhabitats in Arctic landscape: impact of soil type, environmental conditions and soil age

    NASA Astrophysics Data System (ADS)

    Biasi, Christina; Jokinen, Simo; Marushchak, Maija; Trubnikova, Tatiana; Hämäläinen, Kai; Oinonen, Markku; Martikainen, Pertti

    2014-05-01

    methods applied. It seems that the lower decomposability of peat is largely outweighed by higher C stocks at field conditions. Surprisingly, the bare surfaces (peat circles) with 3500 years old C at the surface exhibited about the largest soil microbial respiration rates among all sites as shown by both methods. This is likely due to the immature status of the peat which was during the bulk of its developmental time protected by permafrost, together with high C-densities. The observation is particularly relevant for decomposition of deeper peat at the permafrost-active layer interface in the large vegetated peat plateaus, where soil material similar to the bare surfaces can be found. The results suggest that the chemical nature and high age of the soil SOC in deep peat does not solely guarantee for resistance to decay. Thus, the study highlights risks for potential re-mobilization of C in deep peat soils following thawing. Soil microbial respiration rates need to be better known when predicting the overall carbon sink/source character of tundra ecosystems in a warming climate. Biasi C., Jokinen S., Marushchak M., Hämäläinen K., Trubnikova T., Oinonen M., Martikainen P. (2013). Microbial respiration in Arctic upland and peat soils as source of CO2. Ecosystems. DOI: 10.1007/s10021-013-9710-z.

  15. Conditions of accumulation of radioactive metals in the process of differentiation of ultrabasic alkaline-carbonatite rock associations

    NASA Astrophysics Data System (ADS)

    Kogarko, L. N.

    2014-07-01

    The distribution of radioactive elements in alkaline rocks from Polar Siberia and Ukraine shows that U and Th are markedly concentrated in carbonatite complex and nepheline syenite as final products of magma fractionation. Peralkaline nepheline syenites from Polar Siberia are characterized by very high contents of radioactive elements, which are close to the economic level. Radioactive elements are also concentrated in rocks of the carbonatite complex. For example, some soevites contain up to 294 × 10-4%U and 916 × 10-4% Th. In late dolomite carbonatites, the contents of radioactive elements are appreciably lower. The Th/U ratio in alkaline rocks of Polar Siberia is close to the chondrite value in primary high-Mg rocks and increases in late derivatives: phoscorite, calcite and dolomite carbonatites. The main amount of radioactive elements is contained in rare-metal accessory minerals: perovskite, pyrochlore, calzirtite, and apatite. Rock-forming minerals are distinguished by very low concentrations of radioactive elements. In alkaline series of the Chernigovka massif (Ukraine), U and Th also accumulate in the course of crystal fractionation, especially in phoscorites from the carbonatite complex. Mantle xenoliths and alkaline rocks from Ukraine reveal uranium specialization. Most likely, the discrepancy in fractionation of radioactive elements between Polar Siberia and Ukraine is caused by different geodynamic regimes of these provinces. The Mesozoic alkaline magmatism of Polar Siberia is a part of the Siberian superplume, whereas the Proterozoic alkaline complex in Ukraine is related to subduction of the oceanic crust.

  16. Soil moisture under contrasted atmospheric conditions in Eastern Spain

    NASA Astrophysics Data System (ADS)

    Azorin-Molina, César; Cerdà, Artemi; Vicente-Serrano, Sergio M.

    2014-05-01

    , Intraannual changes, Atmospheric parameters, Eastern Spain Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and RECARE FP7 project 603498 supported this research. References: Azorin-Molina, C., Connell, B.H., Baena-Calatrava, R. 2009. Sea-breeze convergence zones from AVHRR over the Iberian Mediterranean Area and the Isle of Mallorca, Spain. Journal of Applied Meteorology and Climatology 48 (10), 2069-2085. Azorin-Molina, C., Vicente-Serrano, S. M., Cerdà, A. 2013. Soil moisture changes in two experimental sites in Eastern Spain. Irrigation versus rainfed orchards under organic farming. EGU, Geophysical Research Abstracts, EGU2013-13286. 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. 10.1016/j.geoderma.2010.11.009 Cerdà, A. 1995. Soil moisture regime under simulated rainfall in a three years abandoned field in Southeast Spain. Physics and Chemistry of The Earth, 20 (3-4), 271-279. Cerdà, A. 1999. Seasonal and spatial variations in infiltration rates in badland surfaces under Mediterranean climatic conditions. Water Resources Research, 35 (1) 319-328. Cerdà, A. 2002. The effect of season and parent material on water erosion on highly eroded soils in eastern Spain. Journal of Arid Environments, 52, 319-337. García-Fayos, P. García-Ventoso, B. Cerdà, A. 2000. Limitations to Plant establishment on eroded slopes in Southeastern Spain. Journal of Vegetation Science, 11- 77- 86. Ghafoor, A., Murtaza, G., Rehman, M. Z., Saifullah Sabir, M. 2012. Reclamation and salt leaching efficiency for tile drained saline-sodic soil using marginal quality water for irrigating rice and wheat crops. Land Degradation & Development, 23: 1 -9. DOI 10.1002/ldr.1033 Johnston, C. R., Vance, G. F., Ganjegunte, G. K. 2013. Soil properties changes following irrigation with coalbed natural

  17. Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter.

    PubMed

    Lohwacharin, J; Takizawa, S; Punyapalakul, P

    2015-10-01

    We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns.

  18. Evaluation of antibiotic mobility in soil associated with swine-slurry soil amendment under cropping conditions.

    PubMed

    Domínguez, C; Flores, C; Caixach, J; Mita, L; Piña, B; Comas, J; Bayona, J M

    2014-11-01

    Interest in identifying pools of antibacterial-resistance genes has grown over the last decade, with veterinary antibiotics (VAs) receiving particular attention. In this paper, a mesoscale study aimed at evaluating the vertical transport of common VAs-namely, fluoroquinolones, tetracyclines, sulfonamides, and lincosamides in agricultural soil subjected to drip irrigation-was performed under greenhouse conditions. Accordingly, leachates of cropped and uncropped soil, amended with swine-slurry leading to 19-38 μg kg(-1) (dry mass) antibiotics in the soil, were analyzed over the course of the productive cycle of a lettuce (42 days) with three sampling campaigns (N = 24). High lincomycin (LCM) concentrations (30-39 μg L(-1)) were detected in the leachates collected from the swine-slurry-amended soil. The highest LCM mass recovered in the leachates (30.1 ± 1.63 %) was obtained from cropped experimental units. In addition, the LCM leaching constant and its leaching potential as obtained from the first-order model were higher in the leachates from the cropped experimental units. Lower concentrations of sulfadimethoxine were also detected in leachates and in soil. Enrofloxacin and oxytetracycline occurred only in soil, which is consistent with high soil interaction.

  19. Drilling the Mediterranean Messinian Evaporites to Answer Key Questions Related to Massive Microbial Dolomite Formation under Hypersaline Alkaline Conditions

    NASA Astrophysics Data System (ADS)

    McKenzie, Judith A.; Bontognali, Tomaso R. R.; Vasconcelos, Crisogono

    2014-05-01

    Deep-sea drilling in the Mediterranean during DSSP Leg 13 in 1970 revealed the basin-wide occurrence of a Messinian evaporite formation. This spectacular discovery was pursued further during a subsequent drilling program, DSDP Leg 42A, in 1975, which was designed, in part, to obtain continuous cores to study the evolution of the salinity crisis itself (Hsü, Montadert, et al., 1978). Specifically, drilling at a water depth of 4,088 m in the Ionian Sea, DSDP Site 374: Messina Abyssal Plain, penetrated about 80 m into the uppermost part of the Messinian upper evaporite formation. The sedimentary sequence comprises dolomitic mudstone overlying dolomitic mudstone/gypsum cycles, which in turn overlie anhydrite and halite. The non-fossiliferous dolomitic mudstone is generally rich in organic carbon, with TOC values ranging from 0.9% to 5.3%, of possible marine origin with a good source rock potential. Commonly laminated dolomitic mudstones contain preserved filamentous cyanobacterial remains suggesting that conditions were conducive for microbial mat growth. The Ca-dolomite, composed of fine-grained anhedral crystals in the size range of 2-4 μm, is probably a primary precipitate. The unusual interstitial brines of the dolomitic mudstone units have very high alkalinities with a low pH of 5 to 6. The Mg concentration (2250 mmoles/l) is extremely elevated, whereas the Ca concentration is nearly zero. Finally, the drilled evaporite sedimentary sequence was interpreted as being deposited in an alkaline lake/sea ("Lago Mare"), which covered the area during the latest Messinian. Projecting forward 40 years since the DSDP Leg 42A drilling campaign, research into the factors controlling dolomite precipitation under Earth surface conditions has led to the development of new models involving the metabolism of microorganisms and associated biofilms to overcome the kinetic inhibitions associated with primary dolomite precipitation. Together with laboratory experiments, microbial

  20. Bacillus lindianensis sp. nov., a novel alkaliphilic and moderately halotolerant bacterium isolated from saline and alkaline soils.

    PubMed

    Dou, Guiming; Liu, Hongcan; He, Wei; Ma, Yuchao

    2016-01-01

    Two alkaliphilic and halotolerant Gram-stain positive, rod-shaped and endospore-forming bacteria, designated strains 12-3(T) and 12-4, were isolated from saline and alkaline soils collected in Lindian county, Heilongjiang province, China. Both strains were observed to grow well at a wide range of temperature and pH values, 10-45 °C and pH 8-12, with optimal growth at 37 °C and pH 9.0, respectively. Growth of the two strains was found to occur at total salt concentrations of 0-12 % (w/v), with an optimum at 4 % (w/v). The G+C contents of the genomic DNA of strains 12-3(T) and 12-4 were determined to be 42.7 and 42.4 mol%, respectively, and the major cellular fatty acids were identified as anteiso-C15:0 and anteiso-C17:0. In isolate 12-3(T), meso-diaminopimelic acid was found to be the diagnostic diamino acid of the cell wall peptidoglycan; diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol were identified as the major cellular polar lipids; and menaquinone-7 was identified as the predominant isoprenoid quinone. Strains 12-3(T) and 12-4 share very close 16S rRNA gene sequence similarity (99.74 %) and their DNA-DNA relatedness was 95.3 ± 0.63 %, meaning that the two strains can be considered to belong to the same species. 16S rRNA gene sequence-based phylogenetic analysis revealed strains 12-3(T) and 12-4 exhibit high similarities to Bacillus pseudofirmus DSM 8715(T) (98.7 %), Bacillus marmarensis DSM 21297(T) (97.2 %) and Bacillus nanhaiisediminis CGMCC 1.10116(T) (97.1 and 97.0 %, respectively). DNA-DNA hybridization values between isolate 12-3(T) and the type strains of closely related Bacillus species were below 30 %. On the basis of the polyphasic evidence presented, strains 12-3(T) and 12-4 are considered to represent a novel species of the genus Bacillus, for which the name Bacillus lindianensis sp. nov. is proposed. The type strain is 12-3(T) (DSM 26864(T) = CGMCC 1.12717(T)). PMID:26604103

  1. A field study on heavy metals phytoattenuation potential of monocropping and intercropping of maize and/or legumes in weakly alkaline soils.

    PubMed

    Zhu, Saiyong; Ma, Xinwang; Guo, Rui; Ai, Shiwei; Liu, Bailin; Zhang, Wenya; Zhang, Yingmei

    2016-10-01

    The study focused on the phytoattenuation effects of monocropping and intercropping of maize (Zea mays) and/or legumes on Cu, Zn, Pb, and Cd in weakly alkaline soils. Nine growth stages of monocropping maize were chosen to study the dynamic process of extraction of heavy metals. The total content of heavy metals extracted by the aerial part of monocropped maize increased in a sigmoidal pattern over the effective accumulative temperature. The biggest biomass, highest extraction content, and lowest heavy metals bioaccumulation level occurred at physiological maturity. Among the different planting patterns, including monocropping and intercropping of maize and/or soybean (Glycine max), pea (Pisum sativum), and alfalfa (Medicago sativa), the extraction efficiency of Cu, Zn, Pb, and Cd varied greatly. Only intercropping of maize and soybean yielded relatively higher extraction efficiency for the four metals with no significant difference in the total biomass. Moreover, the heavy metals concentrations in dry biomass from all the planting patterns in the present study were within China's national legal thresholds for fodder use. Therefore, slightly polluted alkaline soils can be safely used through monocropping and intercropping of maize and/or legumes for a range of purposes. In particular, this study indicated that intercropping improves soil ecosystems polluted by heavy metals compared with monocropping. PMID:27159531

  2. The Effects of Culture Conditions on the Glycosylation of Secreted Human Placental Alkaline Phosphatase Produced in Chinese Hamster Ovary Cells

    PubMed Central

    Nam, Jong Hyun; Zhang, Fuming; Ermonval, Myriam; Linhardt, Robert J.; Sharfstein, Susan T.

    2009-01-01

    The effects of different culture conditions, suspension and microcarrier culture and temperature reduction on the structures of N-linked glycans attached to secreted human placental alkaline phosphatase (SEAP) were investigated for CHO cells grown in a controlled bioreactor. Both mass spectrometry and anion-exchange chromatography were used to probe the N-linked glycan structures and distribution. Complex-type glycans were the dominant structures with small amounts of high mannose glycans observed in suspension and reduced temperature cultures. Biantennary glycans were the most common structures detected by mass spectrometry, but triantennary and tetraantennary forms were also detected. The amount of sialic acid present was relatively low, approximately 0.4 mol sialic acid/mol SEAP for suspension cultures. Microcarrier cultures exhibited a decrease in productivity compared with suspension culture due to a decrease in both maximum viable cell density (15-20%) and specific productivity (30-50%). In contrast, a biphasic suspension culture in which the temperature was reduced at the beginning of the stationary phase from 37 to 33°C, showed a 7% increase in maximum viable cell density, a 62% increase in integrated viable cell density, and a 133% increase in specific productivity, leading to greater than threefold increase in total productivity. Both microcarrier and reduced temperature cultures showed increased sialylation and decreased fucosylation when compared to suspension culture. Our results highlight the importance of glycoform analysis after process modification as even subtle changes (e.g., changing from one microcarrier to another) may affect glycan distributions. PMID:18553404

  3. Biodegradation of cyanide by a new isolated strain under alkaline conditions and optimization by response surface methodology (RSM)

    PubMed Central

    2014-01-01

    Background Biodegradation of free cyanide from industrial wastewaters has been proven as a viable and robust method for treatment of wastewaters containing cyanide. Results Cyanide degrading bacteria were isolated from a wastewater treatment plant for coke-oven-gas condensate by enrichment culture technique. Five strains were able to use cyanide as the sole nitrogen source under alkaline conditions and among them; one strain (C2) was selected for further studies on the basis of the higher efficiency of cyanide degradation. The bacterium was able to tolerate free cyanide at concentrations of up to 500 ppm which makes it a good potentially candidate for the biological treatment of cyanide contaminated residues. Cyanide degradation corresponded with growth and reached a maximum level 96% during the exponential phase. The highest growth rate (1.23 × 108) was obtained on day 4 of the incubation time. Both glucose and fructose were suitable carbon sources for cyanotrophic growth. No growth was detected in media with cyanide as the sole carbon source. Four control factors including, pH, temperature, agitation speed and glucose concentration were optimized according to central composite design in response surface method. Cyanide degradation was optimum at 34.2°C, pH 10.3 and glucose concentration 0.44 (g/l). Conclusions Bacterial species degrade cyanide into less toxic products as they are able to use the cyanide as a nitrogen source, forming ammonia and carbon dioxide as end products. Alkaliphilic bacterial strains screened in this study evidentially showed the potential to possess degradative activities that can be harnessed to remediate cyanide wastes. PMID:24921051

  4. Soil moisture under contrasted atmospheric conditions in Eastern Spain

    NASA Astrophysics Data System (ADS)

    Azorin-Molina, César; Cerdà, Artemi; Vicente-Serrano, Sergio M.

    2014-05-01

    , Intraannual changes, Atmospheric parameters, Eastern Spain Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and RECARE FP7 project 603498 supported this research. References: Azorin-Molina, C., Connell, B.H., Baena-Calatrava, R. 2009. Sea-breeze convergence zones from AVHRR over the Iberian Mediterranean Area and the Isle of Mallorca, Spain. Journal of Applied Meteorology and Climatology 48 (10), 2069-2085. Azorin-Molina, C., Vicente-Serrano, S. M., Cerdà, A. 2013. Soil moisture changes in two experimental sites in Eastern Spain. Irrigation versus rainfed orchards under organic farming. EGU, Geophysical Research Abstracts, EGU2013-13286. 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. 10.1016/j.geoderma.2010.11.009 Cerdà, A. 1995. Soil moisture regime under simulated rainfall in a three years abandoned field in Southeast Spain. Physics and Chemistry of The Earth, 20 (3-4), 271-279. Cerdà, A. 1999. Seasonal and spatial variations in infiltration rates in badland surfaces under Mediterranean climatic conditions. Water Resources Research, 35 (1) 319-328. Cerdà, A. 2002. The effect of season and parent material on water erosion on highly eroded soils in eastern Spain. Journal of Arid Environments, 52, 319-337. García-Fayos, P. García-Ventoso, B. Cerdà, A. 2000. Limitations to Plant establishment on eroded slopes in Southeastern Spain. Journal of Vegetation Science, 11- 77- 86. Ghafoor, A., Murtaza, G., Rehman, M. Z., Saifullah Sabir, M. 2012. Reclamation and salt leaching efficiency for tile drained saline-sodic soil using marginal quality water for irrigating rice and wheat crops. Land Degradation & Development, 23: 1 -9. DOI 10.1002/ldr.1033 Johnston, C. R., Vance, G. F., Ganjegunte, G. K. 2013. Soil properties changes following irrigation with coalbed natural

  5. Experiments using new initial soil moisture conditions and soil map in the Eta model over La Plata Basin

    NASA Astrophysics Data System (ADS)

    Doyle, Moira E.; Tomasella, Javier; Rodriguez, Daniel A.; Chou, Sin Chan

    2013-08-01

    An effort towards a more accurate representation of soil moisture and its impact on the modeling of weather systems is presented. Sensitivity tests of precipitation to soil type and soil moisture changes are carried out using the atmospheric Eta model for the numerical simulation of the development of a mesoscale convective system over northern Argentina. Modified initial soil moisture conditions were obtained from a hydrological balance model developed and running operationally at INPE. A new soil map was elaborated using the available soil profile information from Brazil, Paraguay, Uruguay, and Argentina and depicts 18 different soil types. Results indicate that more accurate initial soil moisture conditions and incorporating a new soil map with hydraulic parameters, more representative of South American soils, improve daily total precipitation forecasts both in quantitative and spatial representations.

  6. Three Gorges Reservoir Area: soil erosion under natural condition vs. soil erosion under current land use

    NASA Astrophysics Data System (ADS)

    Schönbrodt, Sarah; Behrens, Thorsten; Scholten, Thomas

    2010-05-01

    Apparently, the current most prominent human-induced example for large scale environmental impact is the Three Gorges Dam in China. The flooding alongside the Yangtze River, and its tributaries results in a vast loss of settlement and farmland area with productive, fertile valley soils. Due to the associated high land use dynamic on uphill-sites, the soil resources are underlying high land use pressure. Within our study, the soil erosion under natural conditions is compared to the soil erosion under current land use after the impoundment. Both were modeled using the empirical Universal Soil Loss Equation (USLE) which is able to predict long-term annual soil loss with limited data. The database consists of digital terrain data (45 m resolution DEM, erosive slope length based on Monte-Carlo-Aggregation according to Behrens et al. (2008)), field investigations of recent erosion forms, and literature studies. The natural disposition to soil erosion was calculated considering the USLE factors R, S, and K. The soil erosion under current land use was calculated taking into account all USLE factors. The study area is the catchment of the Xiangxi River in the Three Gorges Reservoir area. Within the Xiangxi Catchment (3,200 km²) the highly dynamic backwater area (580 km²), and two micro-scale study sites (Xiangjiaba with 2.8 km², and Quyuan with 88 km²) are considered more detailed as they are directly affected by the river impoundment. Central features of the Xiangxi Catchment are the subtropical monsoon climate, an extremely steep sloping relief (mean slope angle 39°, SD 22.8°) artificially fractured by farmland terraces, and a high soil erodibility (mean K factor 0.37, SD 0.13). On the catchment scale the natural disposition to soil erosion makes up to mean 518.0 t ha-1 a-1. The maximum potential soil loss of 1,730.1 t ha-1 a-1 under natural conditions is reached in the Quyuan site (mean 635.8 t ha-1 a-1) within the backwater area (mean 582.9 t ha-1 a-1). In the

  7. Human brains found in a fire-affected 4000-years old Bronze Age tumulus layer rich in soil alkalines and boron in Kutahya, Western Anatolia.

    PubMed

    Altinoz, M A; Ince, B; Sav, A; Dincer, A; Cengiz, S; Mercan, S; Yazici, Z; Bilgen, M N

    2014-02-01

    Undecomposed human bodies and organs always attracted interest in terms of understanding biological tissue stability and immortality. Amongst these, cases of natural mummification found in glaciers, bog sediments and deserts caused even more attention. In 2010, an archeological excavation of a Bronze Age layer in a tumulus near the Western Anatolia city Kütahya revealed fire affected regions with burnt human skeletons and charred wooden objects. Inside of the cracked skulls, undecomposed brains were discernible. To analyze the burial taphonomy of the rare phenomenon of brain preservation, we analyzed brains, bone, teeth and surrounding soils elements using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Adipocere formation or saponification of postmortem tissue fat requires high levels of alkalinity and especially potassium. Indeed, ICP-MS analysis of the brain, teeth and bone and also of the surrounding soil revealed high levels of potassium, magnesium, aluminum and boron, which are compatible with the famous role of Kütahya in tile production with its soil containing high level of alkalines and tile-glazing boron. Fatty acid chromatography revealed simultaneous saturation of fats and protection of fragile unsaturated fatty acids consistent with soil-presence of both pro-oxidant and anti-oxidant trace metals. Computerized tomography revealed protection of diencephalic, metencephalic and occipital tissue in one of the best-preserved specimens. Boron was previously found as an intentional preservative of Tutankhamen and Deir el Bahari mummies. Here, in natural soil with its insect-repellant, anti-bacterial and fire-resistance qualities it may be a factor to preserve heat-affected brains as almost bioporcellain specimens. PMID:24060546

  8. Effects of Different Saline-Alkaline Conditions on the Characteristics of Phytoplankton Communities in the Lakes of Songnen Plain, China

    PubMed Central

    Zang, Shuying; Fan, Yawen; Ye, Huaxiang

    2016-01-01

    Many lakes located in the Songnen Plain of China exhibit a high saline-alkaline level. 25 lakes in the Songnen Plain were selected as research objects in this study. Water samples in these lakes were collected from June to August in 2008. Total Dissolved Solids (TDS) and Total Alkalinity (TA) were measured to assess the saline-alkaline level, and partial canonical correspondence analysis (CCA) was conducted as well. The results show that the majority of these lakes in the study area could be categorized into HCO3−-Na+-I type. According to the TDS assessment, of the total 25 lakes, there are 14 for freshwater, 7 for brackish water and 4 for saltwater; and the respective range of TA was from 0.98 to 40.52. The relationship between TA and TDS indicated significant linear relationship (R2 = 0.9292) in the HCO3−-Na+-I type lakes in the Songnen Plain. There was a general trend that cell density, genera richness and taxonomic diversity decreased with the increase of saline-alkaline gradient, whereas a contrary trend was observed for the proportion of dominant species. When the TDS values were above 3×103mg/L and the TA values were above 15mg/L, there was a significant reduction in cell density, genera richness and biodiversity, and their corresponding values were respectively below 10×106 (ind/L), 15 and approximately 2.5. Through the partial canonical correspondence analysis (CCA), 10.7% of the genera variation was explained by pure saline-alkaline variables. Cyclotella meneghiniana, Melosira ambigua and Melosira granulate were found to become the dominant species in most of these lakes, which indicated that there may be rather wide saline-alkaline niches for common dominant species. About one-quarters of the genera which have certain tolerance to salinity and alkalinity preferred to live in the regions with relatively higher saline-alkaline levels in this study. PMID:27749936

  9. Laboratory investigation of boundary condition impacts on nitrate anion exclusion in an unsaturated soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transient unsaturated horizontal column experiments were conducted with a loam soil, under variable boundary conditions, to obtain added insight on anion exclusion processes that impact nitrate transport in soil. The boundary conditions evaluated were column inlet soil water content, initial soil w...

  10. Aerobic granulation utilizing fermented municipal wastewater under low pH and alkalinity conditions in a sequencing batch reactor.

    PubMed

    Leong, Jason; Rezania, Babak; Mavinic, Don S

    2016-01-01

    The aim of this study was to achieve aerobic granulation utilizing fermented municipal wastewater under low pH, and alkalinity conditions. Stable granulation was achieved after a 166-day start-up period. Due to low influent strength, supplemental carbon addition, in the form of sucrose, was added to the feed storage tank on the 82nd day of start-up to facilitate granulation. This increased the system's organic loading rate from 1.43 ± 0.14 to 2.53 ± 0.18 kg COD/m(3)/d, and reduced the influent pH due to fermentation of the added sucrose. Although granulation was successful, the nutrient removal was limited. Removal rates at an influent pH of 6.23 ± 0.06 were 54.4% ± 8.3% for phosphorus, 21.9% ± 4.1% for ammonium, and 84.0% ± 3.0% for total chemical oxygen demand (COD). During the second phase of experimentation, increased amounts of sucrose were added to the feed, which resulted in increased volatile fatty acid concentrations and pH reduction to 5.62 ± 0.12 due to fermentation. Under further reduced pH conditions, phosphorus, ammonium, and total COD removal were found to be 58.9% ± 4.7%, 37.9% ± 4.7%, and 87.1% ± 0.9%, respectively. Settling volume indexes, SVI10 and SVI30, were found to be 148.8 ± 28.9 mL/g, for the influent pH of 6.23 ± 0.06, and 157.5 ± 40.6 mL/g, for the influent pH of 5.62 ± 0.12. This high SVI is indicative of the formation of lower-density granules in comparison to high-ash-content granules. The absence of denitrification-induced chemical phosphorus precipitation within the granule was likely a contributing factor to the low granule density observed in the system.

  11. Bioremediation of carbofuran contaminated soil under saturated condition: soil column study.

    PubMed

    Plangklang, Pensri; Reungsang, Alissara; Suphannafai, Wisarut

    2012-06-01

    Disturbed soil columns, 5.8 cm in diameter and 25 cm in length, were used as a basic model to simulate the movement of carbofuran in rice field soil under saturated conditions. Bioaugmentation using a specific carbofuran degrader, Burkholderia sp. PCL3, in free and immobilized cell forms and biostimulation using rice straw as organic amendment were applied with the aim of enhancing the degradation of carbofuran in soil and to prevent the movement of carbofuran along with the flow through. In the abiotic control and the treatment with only indigenous microorganisms, the mass recovery percentage of carbofuran in the effluent was 52.1 and 22.5%, respectively. The application of bioaugmentation or biostimulation significantly enhanced carbofuran degradation in soil and reduced the movement of carbofuran as indicated by a low mass recovery percentage of carbofuran in the effluent of 14.6-15.5%. A low efficiency of carbofuran removal was obtained from the soil column with bioaugmentation together with biostimulation treatments in which the mass recovery percentage of carbofuran in the effluent was in the range of 22.1-22.6%. Sorption of carbofuran to soil, rice straw and corncob, formation of carbofuran metabolite and colony forming unit (CFU) and pH variation with the time were also investigated during column operation.

  12. Survival of a microbial soil community under Martian conditions

    NASA Astrophysics Data System (ADS)

    Hansen, A. A.; Noernberg, P.; Merrison, J.; Lomstein, B. Aa.; Finster, K. W.

    2003-04-01

    Because of the similarities between Earth and Mars early history the hypothesis was forwarded that Mars is a site where extraterrestrial life might have and/or may still occur(red). Sample-return missions are planned by NASA and ESA to test this hypothesis. The enormous economic costs and the logistic challenges of these missions make earth-based model facilities inevitable. The Mars simulation system at University of Aarhus, Denmark allows microbiological experiments under Mars analogue conditions. Thus detailed studies on the effect of Mars environmental conditions on the survival and the activity of a natural microbial soil community were carried out. Changes in the soil community were determined with a suite of different approaches: 1) total microbial respiration activity was investigated with 14C-glucose, 2) the physiological profile was investigated by the EcoLog-system, 3) colony forming units were determined by plate counts and 4) the microbial diversity on the molecular level was accessed with Denaturing Gradient Gel Electrophoresis. The simulation experiments showed that a part of the bacterial community survived Martian conditions corresponding to 9 Sol. These and future simulation experiments will contribute to our understanding of the possibility for extraterrestrial and terrestrial life on Mars.

  13. High-quality permanent draft genome sequence of Ensifer medicae strain WSM244, a microsymbiont isolated from Medicago polymorpha growing in alkaline soil

    SciTech Connect

    Ardley, Julie; Tian, Rui; O’Hara, Graham; Seshadri, Rekha; Reddy, T. B. K.; Pati, Amrita; Woyke, Tanja; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Howieson, John; Reeve, Wayne

    2015-12-01

    We report that Ensifer medicae WSM244 is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of Medicago species. WSM244 was isolated in 1979 from a nodule recovered from the roots of the annual Medicago polymorpha L. growing in alkaline soil (pH 8.0) in Tel Afer, Iraq. WSM244 is the only acid-sensitive E. medicae strain that has been sequenced to date. It is effective at fixing nitrogen with M. polymorpha L., as well as with more alkaline-adapted Medicago spp. such as M. littoralis Loisel., M. scutellata (L.) Mill., M. tornata (L.) Mill. and M. truncatula Gaertn. This strain is also effective with the perennial M. sativa L. Here we describe the features of E. medicae WSM244, together with genome sequence information and its annotation. The 6,650,282 bp high-quality permanent draft genome is arranged into 91 scaffolds of 91 contigs containing 6,427 protein-coding genes and 68 RNA-only encoding genes, and is one of the rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project proposal.

  14. High-quality permanent draft genome sequence of Ensifer medicae strain WSM244, a microsymbiont isolated from Medicago polymorpha growing in alkaline soil

    DOE PAGES

    Ardley, Julie; Tian, Rui; O’Hara, Graham; Seshadri, Rekha; Reddy, T. B. K.; Pati, Amrita; Woyke, Tanja; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; et al

    2015-12-01

    We report that Ensifer medicae WSM244 is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of Medicago species. WSM244 was isolated in 1979 from a nodule recovered from the roots of the annual Medicago polymorpha L. growing in alkaline soil (pH 8.0) in Tel Afer, Iraq. WSM244 is the only acid-sensitive E. medicae strain that has been sequenced to date. It is effective at fixing nitrogen with M. polymorpha L., as well as with more alkaline-adapted Medicago spp. such as M. littoralis Loisel., M. scutellata (L.) Mill., M. tornata (L.)more » Mill. and M. truncatula Gaertn. This strain is also effective with the perennial M. sativa L. Here we describe the features of E. medicae WSM244, together with genome sequence information and its annotation. The 6,650,282 bp high-quality permanent draft genome is arranged into 91 scaffolds of 91 contigs containing 6,427 protein-coding genes and 68 RNA-only encoding genes, and is one of the rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project proposal.« less

  15. Ethylene Inhibits Root Elongation during Alkaline Stress through AUXIN1 and Associated Changes in Auxin Accumulation.

    PubMed

    Li, Juan; Xu, Heng-Hao; Liu, Wen-Cheng; Zhang, Xiao-Wei; Lu, Ying-Tang

    2015-08-01

    Soil alkalinity causes major reductions in yield and quality of crops worldwide. The plant root is the first organ sensing soil alkalinity, which results in shorter primary roots. However, the mechanism underlying alkaline stress-mediated inhibition of root elongation remains to be further elucidated. Here, we report that alkaline conditions inhibit primary root elongation of Arabidopsis (Arabidopsis thaliana) seedlings by reducing cell division potential in the meristem zones and that ethylene signaling affects this process. The ethylene perception antagonist silver (Ag(+)) alleviated the inhibition of root elongation by alkaline stress. Moreover, the ethylene signaling mutants ethylene response1-3 (etr1-3), ethylene insensitive2 (ein2), and ein3-1 showed less reduction in root length under alkaline conditions, indicating a reduced sensitivity to alkalinity. Ethylene biosynthesis also was found to play a role in alkaline stress-mediated root inhibition; the ethylene overproducer1-1 mutant, which overproduces ethylene because of increased stability of 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE5, was hypersensitive to alkaline stress. In addition, the ethylene biosynthesis inhibitor cobalt (Co(2+)) suppressed alkaline stress-mediated inhibition of root elongation. We further found that alkaline stress caused an increase in auxin levels by promoting expression of auxin biosynthesis-related genes, but the increase in auxin levels was reduced in the roots of the etr1-3 and ein3-1 mutants and in Ag(+)/Co(2+)-treated wild-type plants. Additional genetic and physiological data showed that AUXIN1 (AUX1) was involved in alkaline stress-mediated inhibition of root elongation. Taken together, our results reveal that ethylene modulates alkaline stress-mediated inhibition of root growth by increasing auxin accumulation by stimulating the expression of AUX1 and auxin biosynthesis-related genes.

  16. Ethylene Inhibits Root Elongation during Alkaline Stress through AUXIN1 and Associated Changes in Auxin Accumulation.

    PubMed

    Li, Juan; Xu, Heng-Hao; Liu, Wen-Cheng; Zhang, Xiao-Wei; Lu, Ying-Tang

    2015-08-01

    Soil alkalinity causes major reductions in yield and quality of crops worldwide. The plant root is the first organ sensing soil alkalinity, which results in shorter primary roots. However, the mechanism underlying alkaline stress-mediated inhibition of root elongation remains to be further elucidated. Here, we report that alkaline conditions inhibit primary root elongation of Arabidopsis (Arabidopsis thaliana) seedlings by reducing cell division potential in the meristem zones and that ethylene signaling affects this process. The ethylene perception antagonist silver (Ag(+)) alleviated the inhibition of root elongation by alkaline stress. Moreover, the ethylene signaling mutants ethylene response1-3 (etr1-3), ethylene insensitive2 (ein2), and ein3-1 showed less reduction in root length under alkaline conditions, indicating a reduced sensitivity to alkalinity. Ethylene biosynthesis also was found to play a role in alkaline stress-mediated root inhibition; the ethylene overproducer1-1 mutant, which overproduces ethylene because of increased stability of 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE5, was hypersensitive to alkaline stress. In addition, the ethylene biosynthesis inhibitor cobalt (Co(2+)) suppressed alkaline stress-mediated inhibition of root elongation. We further found that alkaline stress caused an increase in auxin levels by promoting expression of auxin biosynthesis-related genes, but the increase in auxin levels was reduced in the roots of the etr1-3 and ein3-1 mutants and in Ag(+)/Co(2+)-treated wild-type plants. Additional genetic and physiological data showed that AUXIN1 (AUX1) was involved in alkaline stress-mediated inhibition of root elongation. Taken together, our results reveal that ethylene modulates alkaline stress-mediated inhibition of root growth by increasing auxin accumulation by stimulating the expression of AUX1 and auxin biosynthesis-related genes. PMID:26109425

  17. Tools to support maintenance strategies under soft soil conditions

    NASA Astrophysics Data System (ADS)

    Lambert, J. W. M.; van Meerten, J. J.; Woning, M. P.; Eijbersen, M. J.; Huber, M.

    2015-11-01

    Costs for maintenance of infrastructure in municipalities with soft soil underground conditions, are estimated to be almost 40 % higher than in others. As a result, these municipalities meet financial problems that cause overdue maintenance. In some cases municipalities are even afraid to be unable to offer a minimum service level in future. In common, traditional practice, roads and sewerage systems have been constructed in trenches that consist of sandy material that replaces the upper meters of the soft soil. Under influence of its weight, this causes accelerated settlements of the construction. A number of alternative constructions have been developed, e.g. using light-weight materials to limit settlement velocity. In order to limit future maintenance costs, improvement of maintenance strategies is desired. Tools have been and will be developed to support municipalities in improving their maintenance strategies and save money by doing that. A model (BALANS) that weighs the attractiveness of alternative solutions under different soil, environmental and economic circumstances, will be presented.

  18. Phytoremediation of pyrene in a Cecil soil under field conditions.

    PubMed

    Lalande, T L; Skipper, H D; Wolf, D C; Reynolds, C M; Freedman, D L; Pinkerton, B W; Hartel, P G; Grimes, L W

    2003-01-01

    We evaluated the effects of annual ryegrass (Lolium multiflorum Lam.) and phosphorus (P) availability on the dissipation of pyrene added at a concentration of approximately 600 mg kg-1 dry soil in the top 7.5 cm of a Cecil loamy sand (fine, kaolinitic, thermic Typic Kanhapludults) in a 10-month experiment under field conditions in Clemson, South Carolina. Plastic canopies were installed to prevent flooding of plots and raindrop dispersion of pyrene. Treatment factors were pyrene, vegetation, and available P levels. Each of the eight treatments had four replicates. The soil was adjusted to low and high P concentrations (an average of 41 and 66 kg extractable P ha-1, respectively). After a 175-d lag period for all treatments, the rate of pyrene removal followed first-order kinetics. The first-order rate constant was significantly higher in nonvegetated (0.098 d-1) than vegetated treatments (0.034 d-1). These data suggest that the presence of easily biodegradable organic matter from plant roots slowed the removal rate of pyrene. The levels of available P did not affect the rate of pyrene dissipation. Pyrene decreased below the detection limit of 6.25 mg kg-1 dry soil in all treatments after 301 d.

  19. Characterization of Apollo Bulk Soil Samples Under Simulated Lunar Conditions

    NASA Astrophysics Data System (ADS)

    Donaldson Hanna, K. L.; Pieters, C. M.; Thomas, I.; Bowles, N. E.; Greenhagen, B. T.

    2013-12-01

    Remote observations provide key insights into the composition and evolution of planetary surfaces. A fundamentally important component to any remote compositional analysis of planetary surfaces is laboratory measurements of well-characterized samples measured under the appropriate environmental conditions. The vacuum environment of airless bodies like the Moon creates a steep thermal gradient in the upper hundreds of microns of regolith. Lab studies of particulate rocks and minerals as well as selected lunar soils under vacuum and lunar-like conditions have identified significant effects of this thermal gradient on thermal infrared (TIR) spectral measurements [e.g. Logan et al. 1973, Salisbury and Walter 1989, Thomas et al. 2012, Donaldson Hanna et al. 2012]. Such lab studies demonstrate the high sensitivity of TIR emissivity spectra to environmental conditions under which they are measured. To best understand the effects of the near surface-environment of the Moon, a consortium of four institutions with the capabilities of characterizing lunar samples was created. The goal of the Thermal Infrared Emission Studies of Lunar Surface Compositions Consortium (TIRES-LSCC) is to characterize Apollo bulk soil samples with a range of compositions and maturities in simulated lunar conditions to provide better context for the spectral effects due to varying compositions and soil maturity as well as for the interpretation of data obtained by the LRO Diviner Lunar Radiometer and future lunar and airless body thermal emission spectrometers. An initial set of thermal infrared emissivity measurements of the bulk lunar soil samples will be made in three of the laboratories included in the TIRES-LSCC: the Asteroid and Lunar Environment Chamber (ALEC) in RELAB at Brown University, the Simulated Lunar Environment chamber in the Planetary Spectroscopy Facility (PSF) at the University of Oxford, and the Simulated Airless Body Emission Laboratory (SABEL) at the Jet Propulsion Laboratory

  20. Arbuscular mycorrhizal fungal diversity, root colonization, and soil alkaline phosphatase activity in response to maize-wheat rotation and no-tillage in North China.

    PubMed

    Hu, Junli; Yang, Anna; Zhu, Anning; Wang, Junhua; Dai, Jue; Wong, Ming Hung; Lin, Xiangui

    2015-07-01

    Monitoring the effects of no-tillage (NT) in comparison with conventional tillage (CT) on soil microbes could improve our understanding of soil biochemical processes and thus help us to develop sound management strategies. The objective of this study was to compare the species composition and ecological function of soil arbuscular mycorrhizal (AM) fungi during the growth and rotation of crops under NT and CT. From late June 2009 to early June 2010, 32 topsoil (0-15 cm) samples from four individual plots per treatment (CT and NT) were collected at both the jointing and maturation stages of maize (Zea mays L.) and wheat (Triticum aestivum L.) from a long-term experimental field that was established in an Aquic Inceptisol in North China in June 2006. The AM fungal spores were isolated and identified and then used to calculate species diversity indices, including the Shannon- Wiener index (H'), Evenness (E), and Simpson's index (D). The root mycorrhizal colonization and soil alkaline phosphatase activity were also determined. A total of 34 species of AM fungi within nine genera were recorded. Compared with NT, CT negatively affected the soil AM fungal community at the maize sowing stage, leading to decreases in the average diversity indices (from 2.12, 0.79, and 0.82 to 1.79, 0.72, and 0.74 for H', E, and D, respectively), root mycorrhizal colonization (from 28% to 20%), soil alkaline phosphatase activity (from 0.24 to 0.19 mg/g/24 h) and available phosphorus concentration (from 17.4 to 10.5 mg/kg) at the maize jointing stage. However, reductions in diversity indices of H', E, and D were restored to 2.20, 0.81, and 0.84, respectively, at the maize maturation stage. CT should affect the community again at the wheat sowing stage; however, a similar restoration in the species diversity of AM fungi was completed before the wheat jointing stage, and the highest Jaccard index (0.800) for similarity in the species composition of soil AM fungi between CT and NT was recorded at

  1. Arbuscular mycorrhizal fungal diversity, root colonization, and soil alkaline phosphatase activity in response to maize-wheat rotation and no-tillage in North China.

    PubMed

    Hu, Junli; Yang, Anna; Zhu, Anning; Wang, Junhua; Dai, Jue; Wong, Ming Hung; Lin, Xiangui

    2015-07-01

    Monitoring the effects of no-tillage (NT) in comparison with conventional tillage (CT) on soil microbes could improve our understanding of soil biochemical processes and thus help us to develop sound management strategies. The objective of this study was to compare the species composition and ecological function of soil arbuscular mycorrhizal (AM) fungi during the growth and rotation of crops under NT and CT. From late June 2009 to early June 2010, 32 topsoil (0-15 cm) samples from four individual plots per treatment (CT and NT) were collected at both the jointing and maturation stages of maize (Zea mays L.) and wheat (Triticum aestivum L.) from a long-term experimental field that was established in an Aquic Inceptisol in North China in June 2006. The AM fungal spores were isolated and identified and then used to calculate species diversity indices, including the Shannon- Wiener index (H'), Evenness (E), and Simpson's index (D). The root mycorrhizal colonization and soil alkaline phosphatase activity were also determined. A total of 34 species of AM fungi within nine genera were recorded. Compared with NT, CT negatively affected the soil AM fungal community at the maize sowing stage, leading to decreases in the average diversity indices (from 2.12, 0.79, and 0.82 to 1.79, 0.72, and 0.74 for H', E, and D, respectively), root mycorrhizal colonization (from 28% to 20%), soil alkaline phosphatase activity (from 0.24 to 0.19 mg/g/24 h) and available phosphorus concentration (from 17.4 to 10.5 mg/kg) at the maize jointing stage. However, reductions in diversity indices of H', E, and D were restored to 2.20, 0.81, and 0.84, respectively, at the maize maturation stage. CT should affect the community again at the wheat sowing stage; however, a similar restoration in the species diversity of AM fungi was completed before the wheat jointing stage, and the highest Jaccard index (0.800) for similarity in the species composition of soil AM fungi between CT and NT was recorded at

  2. Effect of local soil conditions on site amplification

    SciTech Connect

    Chen, J.C.; Bernreuter, D.L.; Johnson, J.J.

    1983-02-18

    The Seismic Safety Margins Research Program (SSMRP) is developing a complete fully coupled analysis procedure (including methods and computer codes) for estimating the risk of an earthquake-induced radioactive release from a commercial nuclear power plant. The analysis procedure is based upon a state-of-the-art evaluation of the current seismic analysis and design process and explicitly accounts for uncertainties inherent in such a process. In Phase I, the seismic input, the soil-structure interaction, dynamic response of structures and subsystems, and fragility were developed and combined using a probabilistic computational procedure. Demonstration calculations were completed for the Zion nuclear power plant. In Phase II, presently ongoing, additional models, improvements to existing models, and improvements to the probabilistic computational assessment of Zion have been developed. Local site amplification has significant effect on structural response and is a major source of uncertainty. As part of the final Zion analysis in Phase II, an assessment of the local site effect at the Zion site was made using new time histories modified for the Zion soil conditions. In this paper, we briefly describe the approach used to correct the seismic hazard curve and time histories developed in Phase I for local site effects and discuss in some detail the results of our efforts to validate the approach. The principle step in the approach was the use of an equivalent linear iterative technique assuming vertically incident waves to correct a set of time histories appropriate for a rock outcrop for the local soil column. For the Zion soil column this led to large correction factors.

  3. Alkaline battery operational methodology

    DOEpatents

    Sholklapper, Tal; Gallaway, Joshua; Steingart, Daniel; Ingale, Nilesh; Nyce, Michael

    2016-08-16

    Methods of using specific operational charge and discharge parameters to extend the life of alkaline batteries are disclosed. The methods can be used with any commercial primary or secondary alkaline battery, as well as with newer alkaline battery designs, including batteries with flowing electrolyte. The methods include cycling batteries within a narrow operating voltage window, with minimum and maximum cut-off voltages that are set based on battery characteristics and environmental conditions. The narrow voltage window decreases available capacity but allows the batteries to be cycled for hundreds or thousands of times.

  4. An amorphous CoSe film behaves as an active and stable full water-splitting electrocatalyst under strongly alkaline conditions.

    PubMed

    Liu, Tingting; Liu, Qian; Asiri, Abdullah M; Luo, Yonglan; Sun, Xuping

    2015-12-01

    It is attractive but still remains a big challenge to develop non-noble metal bifunctional electrocatalysts efficient for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline conditions. Herein, an amorphous CoSe film electrodeposited on a Ti mesh (a-CoSe/Ti) is demonstrated to exhibit high electrocatalytic activity and stability for both reactions in 1.0 M KOH. It needs overpotentials of 292 and 121 mV to drive 10 mA cm(-2) for OER and HER, respectively. The two-electrode alkaline water electrolyzer affords a water-splitting current of 10 mA cm(-2) at a cell voltage of 1.65 V. This work offers an attractive cost-effective catalytic material toward full water splitting applications.

  5. Soil organic carbon of European forest soils: current stock and projections under climate change conditions

    NASA Astrophysics Data System (ADS)

    Caddeo, Antonio; Marras, Serena; Spano, Donatella; Sirca, Costantino

    2016-04-01

    Soil organic carbon (SOC) represents the largest terrestrial carbon pool, and it is subjected to climate change impacts. In Europe, a limited number of studies makes a wide-scale comparison of SOC stock and changes under climate change conditions, and most of them are related to agricultural soils. In this work, the SOC stock of the forested areas of Europe (obtained from the CORINE 2006 Land Use Map) was assessed at 1 km resolution using the agro-ecosystem SOC model CENTURY. The results of the model were compared with independent observational datasets (i.e. LUCAS Topsoil Survey Database). In addition, climate simulations (RCPs 4.5 and 8.5) using the CMCC (Euro-Mediterranean Centre on Climate Change) and the CORDEX dataset were used to estimate the SOC changes of these areas under climate change conditions.

  6. Effects of Soil Oxygen Conditions and Soil pH on Remediation of DDT-contaminated Soil by Laccase from White Rot Fungi

    PubMed Central

    Zhao, Yuechun; Yi, Xiaoyun

    2010-01-01

    High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5–4.5. PMID:20617049

  7. Effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase from white rot fungi.

    PubMed

    Zhao, Yuechun; Yi, Xiaoyun

    2010-04-01

    High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5-4.5. PMID:20617049

  8. The effect of environmental conditions and soil physicochemistry on phosphate stabilisation of Pb in shooting range soils.

    PubMed

    Sanderson, Peter; Naidu, Ravi; Bolan, Nanthi

    2016-04-01

    The stabilisation of Pb in the soil by phosphate is influenced by environmental conditions and physicochemical properties of the soils to which it is applied. Stabilisation of Pb by phosphate was examined in four soils under different environmental conditions. The effect of soil moisture and temperature on stabilisation of Pb by phosphate was examined by measurement of water extractable and bioaccessible Pb, sequential fractionation and X-ray absorption spectroscopy. The addition of humic acid, ammonium nitrate and chloride was also examined for inhibition or improvement of Pb stability with phosphate treatment. The effect of moisture level varied between soils. In soil MB and DA a soil moisture level of 50% water holding capacity was sufficient to maximise stabilisation of Pb, but in soil TV and PE reduction in bioaccessible Pb was inhibited at this moisture level. Providing moisture at twice the soil water holding capacity did not enhance the effect of phosphate on Pb stabilisation. The difference of Pb stability as a result of incubating phosphate treated soils at 18 °C and 37 °C was relatively small. However wet-dry cycles decreased the effectiveness of phosphate treatment. The reduction in bioaccessible Pb obtained was between 20 and 40% with the most optimal treatment conditions. The reduction in water extractable Pb by phosphate was substantial regardless of incubation conditions and the effect of different temperature and soil moisture regimes was not significant. Selective sequential extraction showed phosphate treatment converted Pb in fraction 1 (exchangeable, acid and water soluble) to fraction 2 (reducible). There were small difference in fraction 4 (residual) Pb and fraction 1 as a result of treatment conditions. X-ray absorption spectroscopy of stabilised PE soil revealed small differences in Pb speciation under varying soil moisture and temperature treatments. The addition of humic acid and chloride produced the greatest effect on Pb speciation in

  9. The effect of environmental conditions and soil physicochemistry on phosphate stabilisation of Pb in shooting range soils.

    PubMed

    Sanderson, Peter; Naidu, Ravi; Bolan, Nanthi

    2016-04-01

    The stabilisation of Pb in the soil by phosphate is influenced by environmental conditions and physicochemical properties of the soils to which it is applied. Stabilisation of Pb by phosphate was examined in four soils under different environmental conditions. The effect of soil moisture and temperature on stabilisation of Pb by phosphate was examined by measurement of water extractable and bioaccessible Pb, sequential fractionation and X-ray absorption spectroscopy. The addition of humic acid, ammonium nitrate and chloride was also examined for inhibition or improvement of Pb stability with phosphate treatment. The effect of moisture level varied between soils. In soil MB and DA a soil moisture level of 50% water holding capacity was sufficient to maximise stabilisation of Pb, but in soil TV and PE reduction in bioaccessible Pb was inhibited at this moisture level. Providing moisture at twice the soil water holding capacity did not enhance the effect of phosphate on Pb stabilisation. The difference of Pb stability as a result of incubating phosphate treated soils at 18 °C and 37 °C was relatively small. However wet-dry cycles decreased the effectiveness of phosphate treatment. The reduction in bioaccessible Pb obtained was between 20 and 40% with the most optimal treatment conditions. The reduction in water extractable Pb by phosphate was substantial regardless of incubation conditions and the effect of different temperature and soil moisture regimes was not significant. Selective sequential extraction showed phosphate treatment converted Pb in fraction 1 (exchangeable, acid and water soluble) to fraction 2 (reducible). There were small difference in fraction 4 (residual) Pb and fraction 1 as a result of treatment conditions. X-ray absorption spectroscopy of stabilised PE soil revealed small differences in Pb speciation under varying soil moisture and temperature treatments. The addition of humic acid and chloride produced the greatest effect on Pb speciation in

  10. Effects of cement alkalinity, exposure conditions and steel-concrete interface on the time-to-corrosion and chloride threshold for reinforcing steel in concrete

    NASA Astrophysics Data System (ADS)

    Nam, Jingak

    Effects of (1) cement alkalinity (low, normal and high), (2) exposure conditions (RH and temperature), (3) rebar surface condition (as-received versus cleaned) and (4) density and distribution of air voids at the steel-concrete interface on the chloride threshold and time-to-corrosion for reinforcing steel in concrete have been studied. Also, experiments were performed to evaluate effects of RH and temperature on the diffusion of chloride in concrete and develop a method for ex-situ pH measurement of concrete pore water. Once specimens were fabricated and exposed to a corrosive chloride solution, various experimental techniques were employed to determine time-to-corrosion, chloride threshold, diffusion coefficient and void density along the rebar trace as well as pore water pH. Based upon the resultant data, several findings related to the above parameters have been obtained as summarized below. First, time for the corrosion initiation was longest for G109 concrete specimens with high alkalinity cement (HA). Also, chloride threshold increased with increasing time-to-corrosion and cement alkalinity. Consequently, the HA specimens exhibited the highest chloride threshold compared to low and normal alkalinity ones. Second, high temperature and temperature variations reduced time-to-corrosion of reinforcing steel in concrete since chloride diffusion was accelerated at higher temperature and possibly by temperature variations. The lowest chloride threshold values were found for outdoor exposed specimens suggesting that variation of RH or temperature (or both) facilitated rapid chloride diffusion. Third, an elevated time-to-corrosion and chloride threshold values were found for the wire brushed steel specimens compared to as-received ones. The higher ratio of [OH-]/[Fe n+] on the wire brushed steel surface compared to that of as-received case can be the possible cause because the higher ratio of this parameter enables the formation of a more protective passive film on

  11. Attenuation of aqueous benzene in soils under saturated flow conditions.

    PubMed

    Kim, S-B; Kim, D-J; Yun, S-T

    2006-01-01

    The fate of aqueous benzene in subsurface was investigated in this study, focusing on the role of sorption and biodegradation on the benzene attenuation under dynamic flow conditions. Two sets of column tests were conducted in Plexiglass flow cells packed uniformly with sandy aquifer materials. The first set of the experiment was conducted with a step-type injection of benzene with different powder activated carbon (PAC) contents: (1) PAC = 0 %; (2) PAC = 0.5 %; (3) PAC = 2.0%. The second set was performed as a pulse-type with different test conditions: (4) benzene; (5) benzene and bacteria (Pseudomonas aeruginosa); (6) benzene and bacteria (P. aeruginosa) with hydrogen peroxide. In addition, numerical experiments were performed to examine the role of sorption processes on the benzene attenuation. In the step mode experiments, the KCl breakthrough curves (BTCs) reached the input concentration while the benzene BTCs were considerably lower than those of KCl with slight retardation for all cases, indicating that both reversible/retardation and irreversible sorption occurred. The pulse type tests showed that attenuation of benzene increased in the presence of bacteria due to biodegradation. The benzene attenuation by microbial degradation increased furthermore in the presence of hydrogen peroxide owing to sufficient supply of dissolved oxygen in soil column. Numerical experiments demonstrated that retardation could not contribute to the attenuation of benzene in soils but could only extend its breakthrough time. Experimental results indicated that aqueous benzene could be attenuated by irreversible sorption and biodegradation during transport through the subsurface. Additionally, the attenuation of aqueous benzene is closely related to organic carbon content and oxygen level existing in contaminated aquifers.

  12. Alkaline unfolding and salt-induced folding of yeast alcohol dehydrogenase under high pH conditions.

    PubMed

    Le, W P; Yan, S X; Li, S; Zhong, H N; Zhou, H M

    1996-06-01

    The conformational changes of yeast alcohol dehydrogenase during unfolding at alkaline pH have been followed by fluorescence emission and circular dichroism spectra. A result of comparison of inactivation and conformational changes shows that much lower values of alkaline pH are required to bring about inactivation than significant conformational change of the enzyme molecule. At pH 9.5, although the enzyme has been completely inactivated, no marked conformational changes can be observed. Even at pH 12, the apparently fully unfolded enzyme retains some ordered secondary structure. After removal of Zn2+ from the enzyme molecule, the conformational stability decreased. At pH 12 by adding the salt, the relatively unfolded state of denatured enzyme changes into a compact conformational state by hydrophobic collapsing. Folded states induced by salt bound ANS strongly, indicating the existence of increased hydrophobic surface. More extensive studies showed that although apo-YADH and holo-YADH exhibited similar behavior, the folding cooperative ability of apo-enzyme was lower than that of holo-enzyme. The above results suggest that the zinc ion plays an important role in helping the folding of YADH and in stabilizing its native conformation.

  13. Water Retention of Extremophiles and Martian Soil Simulants Under Close to Martian Environmental Conditions

    NASA Astrophysics Data System (ADS)

    Jänchen, J.; Bauermeister, A.; Feyh, N.; deVera, J.-P.

    2012-05-01

    We report data about interaction of moisture with soil simulants and extremophiles under Martian environmental conditions contributing on atmosphere/surface modelling and on effects determining the water inventory of the upper soil layer of Mars.

  14. Wireless sensor network for monitoring soil moisture and weather conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A wireless sensor network (WSN) was developed and deployed in three fields to monitor soil water status and collect weather data for irrigation scheduling. The WSN consists of soil-water sensors, weather sensors, wireless data loggers, and a wireless modem. Soil-water sensors were installed at three...

  15. Healthy soil as a necessary condition of human life

    NASA Astrophysics Data System (ADS)

    Sokolov, M. S.; Dorodnykh, Yu. L.; Marchenko, A. I.

    2010-07-01

    The extent of soil degradation and soil pathology in Russia is discussed. The concept of a federal target program “National System of the Chemical and Biological Security of the Russian Federation (2009-2013)” is examined. A definition is given to healthy soil of agrocenoses and its main functional characteristic—ecological stability (including balanced biodiversity, self-cleaning capacity, and suppressive activity of the phytopedocenosis). Urgent applied scientific problems of regional soil sanitation are formulated. Criteria and modern methods of ecological monitoring and assessment of soil quality and health are considered. A systems approach to sanitation of soils infected by highly harmful phytopathogens—the causative agents of root rots of cereal crops—is demonstrated using the induction of soil suppressiveness as an example.

  16. Contributions of groundwater conditions to soil and water salinization

    NASA Astrophysics Data System (ADS)

    Salama, Ramsis B.; Otto, Claus J.; Fitzpatrick, Robert W.

    Salinization is the process whereby the concentration of dissolved salts in water and soil is increased due to natural or human-induced processes. Water is lost through one or any combination of four main mechanisms: evaporation, evapotranspiration, hydrolysis, and leakage between aquifers. Salinity increases from catchment divides to the valley floors and in the direction of groundwater flow. Salinization is explained by two main chemical models developed by the authors: weathering and deposition. These models are in agreement with the weathering and depositional geological processes that have formed soils and overburden in the catchments. Five soil-change processes in arid and semi-arid climates are associated with waterlogging and water. In all represented cases, groundwater is the main geological agent for transmitting, accumulating, and discharging salt. At a small catchment scale in South and Western Australia, water is lost through evapotranspiration and hydrolysis. Saline groundwater flows along the beds of the streams and is accumulated in paleochannels, which act as a salt repository, and finally discharges in lakes, where most of the saline groundwater is concentrated. In the hummocky terrains of the Northern Great Plains Region, Canada and USA, the localized recharge and discharge scenarios cause salinization to occur mainly in depressions, in conjunction with the formation of saline soils and seepages. On a regional scale within closed basins, this process can create playas or saline lakes. In the continental aquifers of the rift basins of Sudan, salinity increases along the groundwater flow path and forms a saline zone at the distal end. The saline zone in each rift forms a closed ridge, which coincides with the closed trough of the groundwater-level map. The saline body or bodies were formed by evaporation coupled with alkaline-earth carbonate precipitation and dissolution of capillary salts. Résumé La salinisation est le processus par lequel la

  17. Determination of arsenic species in soil solution under flooded conditions

    SciTech Connect

    Onken, B.M.; Hossner, L.R.

    1996-09-01

    Greenhouse experiments were conducted to evaluate the relationships between the species and concentrations of As in the soil solution of flooded soils with other parameters including soil pe, pH, Fe, Mn, and type and amount of As added. Two soils were treated with 0, 5, 15, 25, 35, and 45 mg As kg{sup -1} soil added as either Na-arsenate or Na-arsenite and planted with rice (Oryza sativa L.). Soil solution samples were collected during a period of 60 d and analyzed for As. Selective hydrides generation was employed to evaluate both type and quality of As present in the samples. Inorganic As in the form of arsenate and arsenite was found in the soil solution of both soils. The conversion of added arsenite to arsenate occurred within the first 10 d of the experiment when the pe/pH of the soil was not conducive to arsenite stability. Added arsenate was converted to arsenite during the source of the experiment as the pe/pH of the soil declined due to flooding. Arsenate reached a maximum in soil solution at 10 to 20 d after flooding while maximum arsenite concentrations occurred at 20 to 30 d after flooding. The total concentration of As in soil solution generally reached a maximum at 20 to 30 d after flooding, after which time precipitous losses of As from soil solution occurred in all but the highest As treatments. Soil solution As concentrations were not statistically different between planted and unplanted controls. 30 refs., 6 figs., 3 tabs.

  18. Genetic diversity of root nodulating bacteria associated with Retama sphaerocarpa in sites with different soil and environmental conditions.

    PubMed

    Rodríguez-Echeverría, Susana; Moreno, Silvia; Bedmar, Eulogio J

    2014-06-01

    The genetic diversity of root nodulating bacteria isolated from Retama sphaerocarpa was studied using BOX-A1R PCR and phylogenetic analysis of the 16S rRNA region, as well as the housekeeping genes atpD, glnII and recA. A total of 193 isolates were obtained from eight different sites with different soil and environmental conditions in the Iberian Peninsula. These isolates corresponded to 31 different strains that successfully nodulated R. sphaerocarpa seedlings in reinoculation trials. About one-third of the strains clustered with B. canariense or B. cytisi within Bradyrhizobium group I. The remaining strains clustered with B. elkanii/B. pachyrhizi within Bradyrhizobium group II or in separate clades that could represent new lineages. Based on the 16S rRNA and combined atpD+glnII+recA sequences, two to three lineages of root nodulating bacteria were found at each sampling site, except for Collado Garcia where five species were detected. B. canariense and B. elkanii/B. pachyrhizi were the most abundant species, whereas the least abundant were those related to B. retamae and a putative new lineage. B. canariense was found only in soils with neutral and acid pH, whereas B. retamae was the dominant species in alkaline soils. PMID:24461714

  19. Nutrient Transformations in Soils Under Aerobic and Anaerobic Conditions

    NASA Astrophysics Data System (ADS)

    Owens, P.; Lee, L.

    2003-12-01

    Poultry litter is most commonly land applied as a fertilizer for pastures. Soils vary according to landscape position and the biogeochemistry changes within the soils depending on the landscape position. This research focuses on nutrient speciation in aerobic and anaerobic environments. A 3.4 kg Ha-1 chicken litter application rate was used to determine the speciation of nutrients in these two environments. A 50 g sample of Ruston soil was placed in 250 mL centrifuge tubes and continuously stirred in anaerobic and aerobic environments. The Eh and pH were measured daily and a sample was collected at 0, 3, 7, 14 and 21 days. The Eh decreased from around 600 mV at day 0 to near 100 at day 2; whereas the aerobic sample had a decrease to around 450 mV. The pH increased from 6.5 to 7.0 in the anaerobic soil and from 6.5 to around 8.0 in the aerobic soil. The anaerobic soils had a rapid decrease in NO3- and a sharp increase in NH4+ to around 100 mg NH4+ kg-1 soil at day 7. The aerobic soil had an increase in NH4+ to 70 mg Nh4+ kg-1 soil at day 7 then decrease in NH4+ with a corresponding increase in NO3-. Both the anaerobic and aerobic soil had a rapid decrease in PO42- concentrations and remained low for 21 d.

  20. Fe-N-Doped Carbon Capsules with Outstanding Electrochemical Performance and Stability for the Oxygen Reduction Reaction in Both Acid and Alkaline Conditions.

    PubMed

    Ferrero, Guillermo A; Preuss, Kathrin; Marinovic, Adam; Jorge, Ana Belen; Mansor, Noramalina; Brett, Dan J L; Fuertes, Antonio B; Sevilla, Marta; Titirici, Maria-Magdalena

    2016-06-28

    High surface area N-doped mesoporous carbon capsules with iron traces exhibit outstanding electrocatalytic activity for the oxygen reduction reaction in both alkaline and acidic media. In alkaline conditions, they exhibit more positive onset (0.94 V vs RHE) and half-wave potentials (0.83 V vs RHE) than commercial Pt/C, while in acidic media the onset potential is comparable to that of commercial Pt/C with a peroxide yield lower than 10%. The Fe-N-doped carbon catalyst combines high catalytic activity with remarkable performance stability (3500 cycles between 0.6 and 1.0 V vs RHE), which stems from the fact that iron is coordinated to nitrogen. Additionally, the newly developed electrocatalyst is unaffected by the methanol crossover effect in both acid and basic media, contrary to commercial Pt/C. The excellent catalytic behavior of the Fe-N-doped carbon, even in the more relevant acid medium, is attributable to the combination of chemical functions (N-pyridinic, N-quaternary, and Fe-N coordination sites) and structural properties (large surface area, open mesoporous structure, and short diffusion paths), which guarantees a large number of highly active and fully accessible catalytic sites and rapid mass-transfer kinetics. Thus, this catalyst represents an important step forward toward replacing Pt catalysts with cheaper alternatives. In this regard, an alkaline anion exchange membrane fuel cell was assembled with Fe-N-doped mesoporous carbon capsules as the cathode catalyst to provide current and power densities matching those of a commercial Pt/C, which indicates the practical applicability of the Fe-N-carbon catalyst.

  1. Plants increase arsenic in solution but decrease the non-specifically bound fraction in the rhizosphere of an alkaline, naturally rich soil.

    PubMed

    Obeidy, Carole; Bravin, Matthieu N; Bouchardon, Jean-Luc; Conord, Cyrille; Moutte, Jacques; Guy, Bernard; Faure, Olivier

    2016-04-01

    We aimed at determining the major physical-chemical processes that drive arsenic (As) dynamic in the rhizosphere of four species (Holcus lanatus, Dittrichia viscosa, Lotus corniculatus, Plantago lanceolata) tested for phytostabilization. Experiments were performed with an alkaline soil naturally rich in As. Composition of the soil solution of planted and unplanted pots was monitored every 15 days for 90 days, with a focus on the evolution of As concentrations in solution and in the non-specifically bound (i.e. easily exchangeable) fraction. The four species similarly increased As concentration in solution, but decreased As concentration in the non-specifically bound fraction. The major part (60%) of As desorbed from the non-specifically bound fraction in planted pots was likely redistributed on the less available fractions of As on the solid phase. A second part (35%) of desorbed As was taken up by plants. The minor part (5%) of desorbed As supplied As increase in solution. To conclude, plants induced a substantial redistribution of As on the less available fractions in the rhizosphere, as expected in phytostabilization strategies. Plants however concomitantly increased As concentration in the rhizosphere solution which may contribute to As transfer through plant uptake and leaching.

  2. Plants increase arsenic in solution but decrease the non-specifically bound fraction in the rhizosphere of an alkaline, naturally rich soil.

    PubMed

    Obeidy, Carole; Bravin, Matthieu N; Bouchardon, Jean-Luc; Conord, Cyrille; Moutte, Jacques; Guy, Bernard; Faure, Olivier

    2016-04-01

    We aimed at determining the major physical-chemical processes that drive arsenic (As) dynamic in the rhizosphere of four species (Holcus lanatus, Dittrichia viscosa, Lotus corniculatus, Plantago lanceolata) tested for phytostabilization. Experiments were performed with an alkaline soil naturally rich in As. Composition of the soil solution of planted and unplanted pots was monitored every 15 days for 90 days, with a focus on the evolution of As concentrations in solution and in the non-specifically bound (i.e. easily exchangeable) fraction. The four species similarly increased As concentration in solution, but decreased As concentration in the non-specifically bound fraction. The major part (60%) of As desorbed from the non-specifically bound fraction in planted pots was likely redistributed on the less available fractions of As on the solid phase. A second part (35%) of desorbed As was taken up by plants. The minor part (5%) of desorbed As supplied As increase in solution. To conclude, plants induced a substantial redistribution of As on the less available fractions in the rhizosphere, as expected in phytostabilization strategies. Plants however concomitantly increased As concentration in the rhizosphere solution which may contribute to As transfer through plant uptake and leaching. PMID:26707185

  3. Ethylene Inhibits Root Elongation during Alkaline Stress through AUXIN1 and Associated Changes in Auxin Accumulation1

    PubMed Central

    Li, Juan; Xu, Heng-Hao; Liu, Wen-Cheng; Zhang, Xiao-Wei; Lu, Ying-Tang

    2015-01-01

    Soil alkalinity causes major reductions in yield and quality of crops worldwide. The plant root is the first organ sensing soil alkalinity, which results in shorter primary roots. However, the mechanism underlying alkaline stress-mediated inhibition of root elongation remains to be further elucidated. Here, we report that alkaline conditions inhibit primary root elongation of Arabidopsis (Arabidopsis thaliana) seedlings by reducing cell division potential in the meristem zones and that ethylene signaling affects this process. The ethylene perception antagonist silver (Ag+) alleviated the inhibition of root elongation by alkaline stress. Moreover, the ethylene signaling mutants ethylene response1-3 (etr1-3), ethylene insensitive2 (ein2), and ein3-1 showed less reduction in root length under alkaline conditions, indicating a reduced sensitivity to alkalinity. Ethylene biosynthesis also was found to play a role in alkaline stress-mediated root inhibition; the ethylene overproducer1-1 mutant, which overproduces ethylene because of increased stability of 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE5, was hypersensitive to alkaline stress. In addition, the ethylene biosynthesis inhibitor cobalt (Co2+) suppressed alkaline stress-mediated inhibition of root elongation. We further found that alkaline stress caused an increase in auxin levels by promoting expression of auxin biosynthesis-related genes, but the increase in auxin levels was reduced in the roots of the etr1-3 and ein3-1 mutants and in Ag+/Co2+-treated wild-type plants. Additional genetic and physiological data showed that AUXIN1 (AUX1) was involved in alkaline stress-mediated inhibition of root elongation. Taken together, our results reveal that ethylene modulates alkaline stress-mediated inhibition of root growth by increasing auxin accumulation by stimulating the expression of AUX1 and auxin biosynthesis-related genes. PMID:26109425

  4. The Impact of Organic Amendments on Soil Properties Under Mediterranean Climatic Conditions

    NASA Astrophysics Data System (ADS)

    Hueso Gonzalez, Paloma; Francisco Martinez Murillo, Juan; Damian Ruiz Sinoga, Jose

    2014-05-01

    Soil erosion and unsustainable land uses produce adverse effect on SOC content. Soil management techniques and corrections can be applied for soil recovery, especially, with afforestation purposes. This study presents the short term effects of the application of different treatments and amendments on soil properties for soils included in several sets of closed plots located in the experimental area of Pinarillo (Nerja, Spain). The analysed soil properties were: pH, EC, Organic Carbon, total Nitrogen and total Carbon. In order to verify possible differences, we applied the test of Mann-Whitney U in corroboration with the previous homogeneity test of variance. The result of each strategy set compared to the initial condition shows at least one significant modification in the analysed soil properties. Electrical conductivity was the most changeable soil property respect to the initial condition. Similarly, organic carbon content and total organic carbon remained quite similar. However, when all of the strategy sets are compared among them, total carbon was the most significantly changeable property. Mulching, polymers and urban residue seem to highly modify the soil initial conditions. Although soil physic-chemical parameters generally used to evaluate soil quality change very slowly. The analysed soil properties shows significant differences between dry and wet season. This fact, could be indicating the effect of certain seasonality as it is usual in Mediterranean condition.

  5. Effects of changes in straw chemical properties and alkaline soils on bacterial communities engaged in straw decomposition at different temperatures

    PubMed Central

    Zhou, Guixiang; Zhang, Jiabao; Zhang, Congzhi; Feng, Youzhi; Chen, Lin; Yu, Zhenghong; Xin, Xiuli; Zhao, Bingzi

    2016-01-01

    Differences in the composition of a bacterial community engaged in decomposing wheat straw in a fluvo-aquic soil at 15 °C, 25 °C, and 35 °C were identified using barcode pyrosequencing. Functional carbon groups in the decomposing wheat straw were evaluated by 13C-NMR (nuclear magnetic resonance). Actinobacteria and Firmicutes were more abundant, whereas Alphaproteobacteria and Bacteroidetes were less abundant, at higher temperatures during the later stages of decomposition. Differences in the chemical properties of straw accounted for 19.3% of the variation in the community composition, whereas soil properties accounted for more (24.0%) and temperature, for less (7.4%). Carbon content of the soil microbial biomass and nitrogen content of straw were significantly correlated with the abundance of Alphaproteobacteria, Actinobacteria, and Bacteroidetes. The chemical properties of straw, especially the NCH/OCH3, alkyl O-C-O, and O-alkyl functional groups, exercised a significant effect on the composition of the bacterial community at different temperatures during decomposition—results that extend our understanding of bacterial communities associated with the decomposition of straw in agro-ecosystems and of the effects of temperature and chemical properties of the decomposing straw and soil on such communities. PMID:26916902

  6. Eco-toxicological effects of two kinds of lead compounds on forest tree seed in alkaline soil.

    PubMed

    Yang, Nan; Zhou, Fu-Rong; Wang, Jin-Xin

    2016-03-01

    In order to compare the different eco-toxicological effects of lead nitrate and lead acetate on forest tree seed, a biological incubation experiment was conducted to testify the inhibition effects of two lead compounds on rates of seed germination, root and stem elongation, and seedling fresh weight for six plants (Amaorpha fruticosa L., Robinia psedoacacia L., Pinus tabuliformis Carr., Platycladus orientalis L., Koelreuteria paniculata Laxm., Hippophae rhamnoides L.) in soil. The results indicate that the inhibition effects of the two lead compounds on the rates of root elongation of plants were greater than other indices; root elongation can possibly be used as indices to investigate the relationship between lead toxicity and plant response. The response of trees to lead toxicity varied significantly, and the order of tolerance to lead pollution was as follows: Amaorpha fruticosa L. > Platycladus orientalis L. > Koelreuteria paniculata Laxm. > Robinia psedoacacia L. > Pinus tabuliformis Carr. > Hippophae rhamnoides L. Therefore, we suggest that Amaorpha fruticosa L. and Platycladus orientalis L. be used as tolerant plants for soil phytoremediation and Hippophae rhamnoides L. as an indicative plant to diagnose the toxicity of lead pollution on soil quality. Lead nitrate and lead acetate differentially restrain seeds, with seeds being more sensitive to lead nitrate than lead acetate in the soil. Thus, the characteristics of lead compounds should be taken into full consideration to appraise its impact on the environment.

  7. Eco-toxicological effects of two kinds of lead compounds on forest tree seed in alkaline soil.

    PubMed

    Yang, Nan; Zhou, Fu-Rong; Wang, Jin-Xin

    2016-03-01

    In order to compare the different eco-toxicological effects of lead nitrate and lead acetate on forest tree seed, a biological incubation experiment was conducted to testify the inhibition effects of two lead compounds on rates of seed germination, root and stem elongation, and seedling fresh weight for six plants (Amaorpha fruticosa L., Robinia psedoacacia L., Pinus tabuliformis Carr., Platycladus orientalis L., Koelreuteria paniculata Laxm., Hippophae rhamnoides L.) in soil. The results indicate that the inhibition effects of the two lead compounds on the rates of root elongation of plants were greater than other indices; root elongation can possibly be used as indices to investigate the relationship between lead toxicity and plant response. The response of trees to lead toxicity varied significantly, and the order of tolerance to lead pollution was as follows: Amaorpha fruticosa L. > Platycladus orientalis L. > Koelreuteria paniculata Laxm. > Robinia psedoacacia L. > Pinus tabuliformis Carr. > Hippophae rhamnoides L. Therefore, we suggest that Amaorpha fruticosa L. and Platycladus orientalis L. be used as tolerant plants for soil phytoremediation and Hippophae rhamnoides L. as an indicative plant to diagnose the toxicity of lead pollution on soil quality. Lead nitrate and lead acetate differentially restrain seeds, with seeds being more sensitive to lead nitrate than lead acetate in the soil. Thus, the characteristics of lead compounds should be taken into full consideration to appraise its impact on the environment. PMID:26927657

  8. A multi-scale model of the oxygen reduction reaction on highly active graphene nanosheets in alkaline conditions

    NASA Astrophysics Data System (ADS)

    Vazquez-Arenas, Jorge; Ramos-Sanchez, Guadalupe; Franco, Alejandro A.

    2016-10-01

    A multi-scale model based on a mean field approach, is proposed to describe the ORR mechanism on N-GN catalysts in alkaline media. The model implements activation energies calculated with Density Functional Theory (DFT) at the atomistic level, and scales up them into a continuum framework describing the cathode/electrolyte interface at the mesoscale level. The model also considers mass and momentum transports arising in the region next to the rotating electrode for all ionic species and O2; correction of potential drop and electrochemical double-layer capacitance. Most fitted parameters describing the kinetics of ORR elementary reactions are sensitive in the multi-scale model, which results from the incorporation of activation energies using the mean field method, unlike single-scale modelling Errors in the deviations from activation energies are found to be moderate, except for the elementary step (2) related to the formation of O2ads, which can be assigned to the inherent DFT limitations. The consumption of O2ads to form OOHads is determined as the rate-determining step as a result of its highest energy barrier (163.10 kJ mol-1) in the system, the largest error obtained for the deviation from activation energy (28.15%), and high sensitivity. This finding is confirmed with the calculated surface concentration and coverage of electroactive species.

  9. DEVELOPMENT OF AN IMPROVED TITANATE-BASED SORBENT FOR STRONTIUM AND ACTINIDE SEPARATIONS UNDER STRONGLY ALKALINE CONDITIONS

    SciTech Connect

    Hobbs, D.; Peters, T.; Taylor-Pashow, K.; Fink, S.

    2010-02-18

    High-level nuclear waste produced from fuel reprocessing operations at the Savannah River Site (SRS) requires pretreatment to remove {sup 134,137}Cs, {sup 90}Sr, and alpha-emitting radionuclides (i.e., actinides) prior to disposal onsite as low level waste. Separation processes at SRS include the sorption of {sup 90}Sr and alpha-emitting radionuclides onto monosodium titanate (MST) and caustic side solvent extraction of {sup 137}Cs. The MST and separated {sup 137}Cs is encapsulated along with the sludge fraction of high-level waste (HLW) into a borosilicate glass waste form for eventual entombment at a federal repository. The predominant alpha-emitting radionuclides in the highly alkaline waste solutions include plutonium isotopes {sup 238}Pu, {sup 239}Pu, and {sup 240}Pu; {sup 237}Np; and uranium isotopes, {sup 235}U and {sup 238}U. This paper describes recent results evaluating the performance of an improved sodium titanate material that exhibits increased removal kinetics and capacity for {sup 90}Sr and alpha-emitting radionuclides compared to the current baseline material, MST.

  10. Radiochlorine concentration ratios for agricultural plants in various soil conditions.

    PubMed

    Kashparov, V; Colle, C; Levchuk, S; Yoschenko, V; Zvarich, S

    2007-01-01

    Long-term field experiments have been carried out in the Chernobyl exclusion zone in order to determine the parameters governing radiochlorine ((36)Cl) transfer to plants from four types of soil, namely, Podzoluvisol, Greyzem, Phaeozem and Chernozem. Radiochlorine concentration ratios (CR=concentration of (36)Cl in the fresh plant material divided by its concentration in the dried soil in the upper 20 cm layer) were obtained in green peas (2.6+/-0.4), onions (1.5+/-0.5), potatoes (8+/-1), clover (90+/-26) and ryegrass (158+/-88) hay, oat seeds (36+/-23) and straw (305+/-159), wheat seeds (35+/-10) and straw (222+/-82). These values correlate with the stable chlorine values for the same plants. It was shown that (36)Cl plant/soil CR in radish roots (CR=9.7+/-1.4) does not depend on the stable chlorine content in the soil (up to 150 mgkg(-1)), soil type and thus, that stable chlorine CR values (9.4+/-1.2) can also be used for (36)Cl. Injection of additional quantities of stable chlorine into the soil (100 mgkg(-1) of dry soil) with fertilizer does not change the soil-to-plant transfer of (36)Cl. The results from a batch experiment showed that chlorine is retained in the investigated soils only by live biota and transfers quickly (in just a few hours) into the soil solution from dry vegetation even without decomposition of dead plants and is integrated in the migration processes in soil.

  11. Greenhouse gas emissions from soil under changing environmental conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This manuscript is the Guest Editors’ Introduction to a special issue on greenhouse gas emissions from agriculture. The papers were assembled following presentation at EuroSoil 2012. Exchange of greenhouse gases between soils and the atmosphere is a natural consequence of several ecosystem process...

  12. Examining the fixation kinetics of chelated and non-chelated copper micronutrient and the applications to micronutrient management in semi-arid alkaline soils

    NASA Astrophysics Data System (ADS)

    Udeigwe, T. K.; Eichmann, M. B.; Menkiti, M. C.

    2015-10-01

    The relationship between the deficiency of a nutrient in plants and its total concentration in the soil is complex. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (Ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semi-arid soils of the Southern High Plains, US using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrient over time, highlighting the significance of timing even when chelated micronutrients are applied. The strengths of the relationship of change in available Cu with respect to other micronutrients [iron (Fe), manganese (Mn), and zinc (Zn)] were higher in the non-chelated system (R2: 0.68-0.94), compared to the chelated (R2: 0.42-0.81) with slopes of 0.40 (Cu-Fe), 0.31 (Cu-Mn), and 1.04 (Cu-Zn) in the non-chelated system and 0.26 (Cu-Fe), 0.22 (Cu-Mn), and 0.90 (Cu-Zn) in the chelated. Reduction in the amount of available Cu was best described by the power function model (R2 = 0.91, SE = 0.081) in the non-chelated system and second order model (R2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semi-arid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

  13. [Morphology of soil iron oxides and its correlation with soil-forming process and forming conditions in a karst mountain].

    PubMed

    Zhang, Zhi-Wei; Zhu, Zhang-Xiong; Fu, Wa-Li; Wen, Zhi-Lin

    2012-06-01

    The quantity and morphology of iron oxides are indicators of soil forming-process and forming conditions. In order to analyze the connection between soil iron oxides and soil forming conditions and degenerative process of karst ecosystem, we have chosen 14 soil profiles on the top and middle section of Jinfo Mountain, a typical karst slope in Chongqing, China. Morphology and contents of soil iron oxides were studied by using chemical selective extraction techniques. We draw conclusions: 1) total iron (Fe(t)) is mainly controlled by parent material and lithology. Significant difference of Fe(t) content exists between soils in Top Mountain (51.49 g x kg(-1), mean value from 5 profiles) and soils at the middle sector of North Slope (86.29 g x kg(-1), mean value of 9 profiles); 2) the results show low concentration of F(d) (29.16 g x kg(-1)) and low ratio of Fe(d) to Fe(t)(35.40%) in soil clay under conditions of high elevation and low temperature on Top Mountain. In contrast, the results indicate advanced weathering and soil-forming process at middle slope sites due to high temperature; this is supported by high mean values of Fe(d) (43.92 g x kg(-1)) and ratio of Fe(d)/Fe(t) in clay (60.41%); 3) long humid climatic setting and large numbers of soil organic matter on top of the mountain result in high activation degrees (F(o)/Fe(d)) and high complexation degrees (Fe(p)/Fe(d)); mean values of them are 73.51%, 17.21% respectively, which are higher than that of soils at middle slope sites (13.06%, 0.41%); 4) after degradation or deforestation of secondary forestland (pines massoniana among bushes) at middle section of the hillslope, soil free iron oxides (Fe(d)) and total iron oxides (Fe(t)) decrease as well as soil organic carbon and clay, because of progressively increasing of soil erosion. Average contents of Fe(t) and Fe(d) in clay from 2 shrub profiles are 98.25 g x kg(-1), 50.81 g x kg(-1) respectively. However, the four tillage soils we have studied reveal lower

  14. SUBSURFACE SOIL CONDITIONS BENEATH AND NEAR BUILDINGS AND THE POTENTIAL EFFECTS ON SOIL VAPOR INTRUSION

    EPA Science Inventory

    Migration of volatile chemicals from the subsurface into overlying buildings is called vapor intrusion. Volatile organic chemicals in contaminated soils or groundwater can emit vapors that may migrate through subsurface soils and enter indoor air spaces of overlying buildings. T...

  15. Mobility of spiromesifen in packed soil columns under laboratory conditions.

    PubMed

    Mate, Ch Jamkhokai; Mukherjee, Irani; Das, Shaon Kumar

    2014-11-01

    On percolating water equivalent to 1,156 mm of rainfall, spiromesifen formulation did not leach out of 25-cm long columns, and 62.7 % of this was recovered in 5-10-cm soil depth. In columns treated with the analytical grade, 52.40 % of the recovered spiromesifen was confined to 0-5-cm soil depth, with 0.04 % in leachate fraction, suggesting high adsorption in soil. Results revealed that percolating 400 mL of water, residues of enol metabolite of spiromesifen was detected up to 20-25-cm soil layer, with 23.50 % residues of spiromesifen in this layer and 1.73 % in the leachate fraction indicating that metabolite is more mobile as compared to the parent compound. Results suggested a significant reduction in leaching losses of enol metabolite in amended soil columns with 5 % nano clay, farmyard manure (FYM), and vermicompost. No enol spiromesifen was recovered in the leachate in columns amended with nano clay, vermicompost, and FYM; however, 85.30, 70.5, and 65.40 %, respectively, was recovered from 0-5 cm-soil depth of column after percolating water equivalent to 1,156 mm of rainfall. Spiromesifen formulation is less mobile in sandy loam soil than analytical grade spiromesifen. The metabolite, enol spiromesifen, is relatively more mobile than the parent compound and may leach into groundwater. The study suggested that amendments were very effective in reducing the downward mobility of enol metabolite in soil column. Further, it resulted in greater retention of enol metabolite in the amendment application zone. PMID:25060860

  16. The impact of standard preparation practice on the runoff and soil erosion rates under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Khaledi Darvishan, Abdulvahed; Homayounfar, Vafa; Hamidreza Sadeghi, Seyed

    2016-09-01

    The use of laboratory methods in soil erosion studies, rainfall simulation experiments, Gerlach troughs, and other measurements such as ring infiltrometer has been recently considered more and more because of many advantages in controlling rainfall properties and high accuracy of sampling and measurements. However, different stages of soil removal, transfer, preparation and placement in laboratory plots cause significant changes in soil structure and, subsequently, the results of runoff, sediment concentration and soil loss. Knowing the rate of changes in sediment concentration and soil loss variables with respect to the soil preparation for laboratory studies is therefore inevitable to generalize the laboratory results to field conditions. However, there has been little attention given to evaluate the effects of soil preparation on sediment variables. The present study was therefore conducted to compare sediment concentration and soil loss in natural and prepared soil. To achieve the study purposes, 18 field 1 × 1 m plots were adopted in an 18 % gradient slope with sandy-clay-loam soil in the Kojour watershed, northern Iran. A portable rainfall simulator was then used to simulate rainfall events using one or two nozzles of BEX: 3/8 S24W for various rainfall intensities with a constant height of 3 m above the soil surface. Three rainfall intensities of 40, 60 and 80 mm h-1 were simulated on both prepared and natural soil treatments with three replications. The sediment concentration and soil loss at five 3 min intervals after time to runoff were then measured. The results showed the significant increasing effects of soil preparation (p ≤ 0.01) on the average sediment concentration and soil loss. The increasing rates of runoff coefficient, sediment concentration and soil loss due to the study soil preparation method for laboratory soil erosion plots were 179, 183 and 1050 % (2.79, 2.83 and 11.50 times), respectively.

  17. Impact of redox conditions on metolachlor and metribuzin degradation in Mississippi flood plain soils.

    PubMed

    Mulbach, C K; Porthouse, J D; Jugsujinda, A; DeLaune, R D; Johnson, A B

    2000-11-01

    The effect of soil redox conditions on the degradation of metolachlor and metribuzin in two Mississippi soils (Forrestdale silty clay loam and Loring silt loam) were examined in the laboratory. Herbicides were added to soil in microcosms and incubated either under oxidized (aerobic) or reduced (anaerobic) conditions. Metolachlor and metribuzin degradation under aerobic condition in the Forrestdale soil proceeded at rates of 8.83 ngd(-1) and 25 ngd(-1), respectively. Anaerobic degradation rates for the two herbicides in the Forestdale soil were 8.44 ngd(-1) and 32.5 ngd(-1), respectively. Degradation rates for the Loring soil under aerobic condition were 24.8 ngd(-1) and 12.0 ngd(-1) for metolachlor and metribuzin, respectively. Metolachlor and metribuzin degradation rates under anaerobic conditions in the Loring soil were 20.9 ngd(-1) and 5.35 ngd(-1). Metribuzin degraded faster (12.0 ngd(-1)) in the Loring soil under aerobic conditions as compared to anaerobic conditions (5.35 ngd(-1)).

  18. Effects of agricultural practices of three crops on the soil communities under Mediterranean conditions: field evaluation.

    NASA Astrophysics Data System (ADS)

    Leitão, Sara; José Cerejeira, Maria; Abreu, Manuela; Sousa, José Paulo

    2014-05-01

    Sustainable agricultural production relies on soil communities as the main actors in key soil processes necessary to maintain sustainable soil functioning. Soil biodiversity influences soil physical and chemical characteristics and thus the sustainability of crop and agro-ecosystems functioning. Agricultural practices (e.g.: soil tillage, pesticides and fertilizer applications, irrigation) may affects negatively or positively soil biodiversity and abundances by modifying the relationships between organisms in the soil ecosystem. The present study aimed to study the influence of agricultural practices of three crops (potato, onion and maize) under Mediterranean climate conditions on soil macro- and mesofauna during their entire crop cycles. Effects on soil communities were assessed at a higher tier of environmental risk assessment comprising field testing of indigenous edaphic communities in a selected study-site located in a major agriculture region of Central Portugal, Ribatejo e Oeste, neighbouring protected wetlands. A reference site near the agricultural field site was selected as a Control site to compare the terrestrial communities' composition and variation along the crop cycle. The field soil and Control site soil are sandy loam soils. Crops irrigation was performed by center-pivot (automated sprinkler that rotates in a half a circle area) and by sprinklers. Soil macro- and mesofauna were collected at both sites (field and Control) using two methodologies through pitfall trapping and soil sampling. The community of soil macro- and mesofauna of the three crops field varied versus control site along the crops cycles. Main differences were due to arachnids, coleopterans, ants and adult Diptera presence and abundance. The feeding activity of soil fauna between control site and crop areas varied only for potato and onion crops vs. control site but not among crops. Concentration of pesticides residues in soil did not cause apparent negative effects on the soil

  19. Free energy distribution and hydrothermal mineral precipitation in Hadean submarine alkaline vent systems: Importance of iron redox reactions under anoxic conditions

    NASA Astrophysics Data System (ADS)

    Shibuya, Takazo; Russell, Michael J.; Takai, Ken

    2016-02-01

    Thermodynamic calculations of mixing between hypothetical seawater and hydrothermal fluid in the Hadean deep ocean were carried out to predict saturation states of mineral precipitates and redox reactions that could occur in Hadean submarine alkaline hydrothermal systems associated with the serpentinization of ultramafic rocks. In the calculations, the seawater was assumed to be weakly acidic (pH = 5.5) and to include carbon dioxide, ferrous iron and silica, with or without nitrate, while the Hadean hydrothermal fluid was assumed to be highly alkaline (pH = 11) and to contain abundant molecular hydrogen, methane and bisulfide, based on the Archean geologic record, the modern low-temperature alkaline hydrothermal vent fluid (Lost City field), and experimental and theoretical considerations. The modeling indicates that potential mineral precipitates in the mixing zone (hydrothermal chimney structures) could consist mainly of iron sulfides but also of ferrous serpentine and brucite, siderite, and ferric iron-bearing minerals such as goethite, hematite and/or magnetite as minor phases. The precipitation of ferric iron-bearing minerals suggests that chemical iron oxidation would be made possible by pH shift even under anoxic condition. In the mixing zone, comprising an inorganic barrier precipitated at the interface of the two contrasting solutions, various redox reactions release free energy with the potential to drive endergonic reactions, assuming the involvement of coupling inorganic protoenzymes. Hydrogenotrophic methanogenesis and acetogenesis - long considered the most ancient forms of biological energy metabolisms - are able to achieve higher maximum energy yield (>0.5 kJ/kg hydrothermal fluid) than those in the modern serpentinization-associated seafloor hydrothermal systems (e.g., Kairei field). Furthermore, the recently proposed methanotrophic acetogenesis pathway was also thermodynamically investigated. It is known that methanotrophic acetogenesis would

  20. Modelling agricultural suitability along soil transects under current conditions and improved scenario of soil factors

    NASA Astrophysics Data System (ADS)

    Abd-Elmabod, Sameh K.; Jordán, Antonio; Fleskens, Luuk; van der Ploeg, Martine; Muñoz-Rojas, Miriam; Anaya-Romero, María; van der Salm, Renée J.; De la Rosa, Diego

    2015-04-01

    Agricultural land suitability analysis and improvement of soils by addressing major limitations may be a strategy for climate change adaptation. This study aims to investigate the influence of topography and variability of soil factors on the suitability of 12 annual, semiannual and perennial Mediterranean crops in the province of Seville (southern Spain). In order to represent the variability in elevation, lithology and soil, two latitudinal and longitudinal (S-N and W-E) soil transects (TA and TB) were considered including 63 representative points at regular 4 km intervals. These points were represented by 41 soil profiles from the SDBm soil database -Seville. Almagra model, a component of the agro-ecological decision support system MicroLEIS, was used to assess soil suitability. Results were grouped into five soil suitability classes: S1-optimum, S2-high, S3-moderate, S4-marginal and S5-not suitable. Each class was divided in subclasses according to the main soil limiting factors: depth (p), texture (t), drainage (d), carbonate content (c), salinity (s), sodium saturation (a), and the degree of development of the soil profile (g). This research also aimed to maximize soil potential by improving limiting factors d, c, s and a after soil restoration. Therefore, management techniques were also considered as possible scenarios in this study. The results of the evaluation showed that soil suitability ranged between S1 and S5p - S5s along of the transects. In the northern extreme of transect TA, high content of gravels and coarse texture are limiting factors (soils are classified as S4t) In contrast, the limiting factor in the eastern extreme of transect TB is the shallow useful depth (S5p subclass). The absence of calcium carbonate becomes a limiting factor in some parts of TA. In contrast, the excessive content of calcium carbonate appeared to be a limiting factor for crops in some intermediate points of TB transect. For both transects, soil salinity is the main

  1. Nitrogen release from rock and soil under simulated field conditions

    USGS Publications Warehouse

    Holloway, J.M.; Dahlgren, R.A.; Casey, W.H.

    2001-01-01

    A laboratory study was performed to simulate field weathering and nitrogen release from bedrock in a setting where geologic nitrogen has been suspected to be a large local source of nitrate. Two rock types containing nitrogen, slate (1370 mg N kg-1) and greenstone (480 mg N kg-1), were used along with saprolite and BC horizon sand from soils derived from these rock types. The fresh rock and weathered material were used in batch reactors that were leached every 30 days over 6 months to simulate a single wet season. Nitrogen was released from rock and soil materials at rates between 10-20 and 10-19 mo1 N cm-2 s-1. Results from the laboratory dissolution experiments were compared to in situ soil solutions and available mineral nitrogen pools from the BC horizon of both soils. Concentrations of mineral nitrogen (NO3- + NH4+) in soil solutions reached the highest levels at the beginning of the rainy season and progressively decreased with increased leaching. This seasonal pattern was repeated for the available mineral nitrogen pool that was extracted using a KCl solution. Estimates based on these laboratory release rates bracket stream water NO3-N fluxes and changes in the available mineral nitrogen pool over the active leaching period. These results confirm that geologic nitrogen, when present, may be a large and reactive pool that may contribute as a non-point source of nitrate contamination to surface and ground waters. ?? 2001 Elsevier Science B.V. All rights reserved.

  2. Examining the fixation kinetics of chelated and non-chelated copper and the applications to micronutrient management in semiarid alkaline soils

    NASA Astrophysics Data System (ADS)

    Udeigwe, T. K.; Eichmann, M. B.; Menkiti, M. C.; Kusi, N. Y. O.

    2016-02-01

    This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semiarid soils of the Southern High Plains, USA, using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system compared to the chelated within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrients over time, highlighting the significance of timing even when chelated micronutrients are used. The strengths of the relationship of change in available Cu with respect to other micronutrients (iron (Fe), manganese (Mn), and zinc (Zn)) were higher in the non-chelated system (R2: 0.68-0.94), compared to the chelated (R2: 0.42-0.81), with slopes of 0.40 (Cu-Fe), 0.31 (Cu-Mn), and 1.04 (Cu-Zn) in the non-chelated system and 0.26 (Cu-Fe), 0.22 (Cu-Mn), and 0.90 (Cu-Zn) in the chelated system. Reduction in the amount of available Cu was best described by the power function model (R2 = 0.91, SE = 0.081) in the non-chelated system and second-order model (R2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semiarid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

  3. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    NASA Astrophysics Data System (ADS)

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo

    2016-08-01

    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  4. Purification and partial characterization of a detergent and oxidizing agent stable alkaline protease from a newly isolated Bacillus subtilis VSG-4 of tropical soil.

    PubMed

    Giri, Sib Sankar; Sukumaran, V; Sen, Shib Sankar; Oviya, M; Banu, B Nazeema; Jena, Prasant Kumar

    2011-06-01

    An extracellular detergent tolerant protease producing strain VSG-4 was isolated from tropical soil sample and identified as Bacillus subtilis based on morphological, biochemical characteristics as well as 16S-rRNA gene sequencing. The VSG-4 protease was purified to homogeneity using ammonium sulphate precipitation, dialysis and sephadex G-200 gel permeation chromatography with a 17.4 purification fold. The purified enzyme was active and stable over a broad range of pH (8.0-11.0, optimum at 9.0) and temperature (40°C to 60°C, optimum at 50°C). The thermostability of the enzyme was significantly increased by the addition CaCl(2). This enzyme was strongly inhibited by PMSF and DFP, suggesting that it belongs to the serine protease superfamily. The purified VSG-4 alkaline protease showed remarkable stability in anionic (5 mM SDS) and ionic (1% Trion X-100 and 1% Tween 80) detergents. It retained 97±2% and 83.6±1.1% of its initial activity after 1 h preincubation in the presence of 1 % H(2)O(2) and 1 % sodium perborate, respectively. Furthermore, the purified enzyme showed excellent stability and compatibility with some commercial laundry detergents besides its stain removal capacity. Considering these promising properties, VSG-4 protease may find tremendous application in laundry detergent formulations.

  5. Microbial bioavailability of pyrene in three laboratory-contaminated soils under aerobic and anaerobic conditions.

    PubMed

    Pravecek, Tasha L; Christman, Russell F; Pfaender, Frederic K

    2006-06-30

    Changes in bioavailability of pyrene in three uncontaminated soils were examined under aerobic and anaerobic conditions. Three soils were aerobically aged with pyrene and [(14)C]pyrene for 63 days, then incubated with water, nitrate, or sulfate under aerobic or anaerobic conditions for one year. Under aerobic conditions, microorganisms in two soils mineralized 58-82% of the added [(14)C]pyrene. The two soils amended with nitrate were seen to have enhanced aerobic mineralization rates. In one of these soils, non-extractable pyrene was seen to decrease over the course of the study due to desorption and mineralization, nitrate amendment enhanced this effect. Under anaerobic conditions, generated with a N(2):CO(2)(g) headspace, two soils with nitrate or sulfate amendment showed an increase in extractable [(14)C]pyrene at 365 days relative to inhibited controls, presumably due to microbially mediated oxidation-reduction potential and pH alteration of the soil environment. These observations in different soils incubated under aerobic and anaerobic conditions have important implications relative to the impact of microbial electron acceptors on bioavailability and transport of non-polar organic compounds in the environment suggesting that, given enough time, under the appropriate environmental conditions, non-extractable material becomes bioavailable. This information should be considered when assessing site specific exposure risks at PAH contaminated locations. PMID:16574273

  6. Release of Pharmaceuticals under Reducing Conditions in a Wastewater-Irrigated Mexican Soil.

    PubMed

    Dalkmann, Philipp; Dresemann, Tim-Fabian; Siebe, Christina; Mansfeldt, Tim; Amelung, Wulf; Siemens, Jan

    2014-11-01

    Wastewater irrigation is often performed by flood irrigation, leading to changes in redox potential (Eh) of irrigated soils. In addition to soil organic matter, Fe-(hydr)oxides are important sorbents for pollutants, and biotransformation of pollutants can be accelerated under reducing conditions. Here, the influence of reducing conditions on the release of sorbed pharmaceuticals from soil and their potential accelerated dissipation was investigated in a microcosm study. Samples of a soil from the Mezquital Valley (Mexico) irrigated for 85 yr with untreated wastewater were incubated under oxidizing (Eh of 500 ± 20 mV), weakly reducing (Eh of 100 ± 20 mV), and moderately reducing (Eh of -100 ± 20 mV) soil conditions for 30 to 31 d. The concentrations of nine pharmaceuticals (bezafibrate, carbamazepine, ciprofloxacin, sulfamethoxazole, trimethoprim, enrofloxacin, clarithromycin, diclofenac, and naproxen) were extracted via solid-phase extraction from soil slurries and analyzed by liquid chromatography-tandem mass spectrometry. Low Eh did not lead to a release of formerly sorbed pharmaceuticals from the wastewater irrigated soil. High pH values (>8) of the examined soil resulting from denitrification under reducing conditions prevented the dissolution of Fe-(hydr)oxides and, hence, the potential release of pharmaceuticals. A trend of decreasing concentrations of sulfamethoxazole and bezafibrate with time under moderately reducing conditions supports previous findings of a transformation of these compounds under anaerobic conditions. PMID:25602209

  7. Soil metabolism of [14C]methiozolin under aerobic and anaerobic flooded conditions.

    PubMed

    Hwang, Ki-Hwan; Lim, Jong-Soo; Kim, Sung-Hun; Chang, Hee-Ra; Kim, Kyun; Koo, Suk-Jin; Kim, Jeong-Han

    2013-07-17

    Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(14)C]- and [isoxazole-(14)C]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(14)C]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(14)C]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(14)C]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(14)C]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(14)C]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(14)C]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil. PMID:23772889

  8. Soil metabolism of [14C]methiozolin under aerobic and anaerobic flooded conditions.

    PubMed

    Hwang, Ki-Hwan; Lim, Jong-Soo; Kim, Sung-Hun; Chang, Hee-Ra; Kim, Kyun; Koo, Suk-Jin; Kim, Jeong-Han

    2013-07-17

    Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(14)C]- and [isoxazole-(14)C]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(14)C]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(14)C]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(14)C]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(14)C]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(14)C]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(14)C]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil.

  9. Soil, water, and vegetation conditions in south Texas

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Gausman, H. W.; Leamer, R. W.; Richardson, A. J.; Everitt, J. H.; Gerbermann, A. H. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. Software development for a computer-aided crop and soil survey system is nearing completion. Computer-aided variety classification accuracies using LANDSAT-1 MSS data for a 600 hectare citrus farm were 83% for Redblush grapefruit and 91% for oranges. These accuracies indicate that there is good potential for computer-aided inventories of grapefruit and orange citrus orchards with LANDSAT-type MSS data. Mean digital values of clouds differed statistically from those for crop, soil, and water entities, and those for cloud shadows were enough lower than sunlit crop and soil to be distinguishable. The standard errors of estimate for the calibration of computer compatible tape coordinate system (pixel and record) to earth coordinate system (longitude and latitude) for 6 LANDSAT scenes ranged from 0.72 to 1.50 pixels and from 0.58 to 1.75 records.

  10. Soil, water, and vegetation conditions in south Texas

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Gausman, H. W.; Leamer, R. W.; Richardson, A. J.; Everitt, J. H.; Gerbermann, A. H. (Principal Investigator)

    1977-01-01

    The author has identified the following significant results. The best wavelengths in the 0.4 to 2.5 micron interval were determined for detecting lead toxicity and ozone damage, distinguishing succulent from woody species, and detecting silverleaf sunflower. A perpendicular vegetation index, a measure of the distance from the soil background line, in MSS 5 and MSS 7 data space, of pixels containing vegetation was developed and tested as an indicator of vegetation development and crop vigor. A table lookup procedure was devised that permits rapid identification of soil background and green biomass or phenological development in LANDSAT scenes without the need for training data.

  11. Soil-pore water distribution of silver and gold engineered nanoparticles in undisturbed soils under unsaturated conditions.

    PubMed

    Tavares, D S; Rodrigues, S M; Cruz, N; Carvalho, C; Teixeira, T; Carvalho, L; Duarte, A C; Trindade, T; Pereira, E; Römkens, P F A M

    2015-10-01

    Release of engineered nanoparticles (ENPs) to soil is well documented but little is known on the subsequent soil-pore water distribution of ENPs once present in soil. In this study, the availability and mobility of silver (Ag) and gold (Au) ENPs added to agricultural soils were assessed in two separate pot experiments. Pore water samples collected from pots from day 1 to 45 using porous (<0.17 μm) membrane samplers suggest that both Ag and Au are retained almost completely within 24 h with less than 13% of the total added amount present in pore water on day 1. UV-Vis and TEM results showed that AuENPs in pore water were present as both homoaggregates and heteroaggregates until day 3 after which the concentration in pore water was too low to detect the presence of aggregates. A close relation between the concentration of Au and Fe in pore water suggests that the short term solubility of Au is partly controlled by natural soil colloids. Results suggest that under normal aerated soil conditions the actual availability of Ag and AuENPs is low which is relevant in view of risk assessment even though the impact of environmental conditions and soil properties on the reactivity of ENPs (and/or large ENPs aggregates) retained in the solid matrix need to be addressed further. PMID:25965160

  12. Soil-pore water distribution of silver and gold engineered nanoparticles in undisturbed soils under unsaturated conditions.

    PubMed

    Tavares, D S; Rodrigues, S M; Cruz, N; Carvalho, C; Teixeira, T; Carvalho, L; Duarte, A C; Trindade, T; Pereira, E; Römkens, P F A M

    2015-10-01

    Release of engineered nanoparticles (ENPs) to soil is well documented but little is known on the subsequent soil-pore water distribution of ENPs once present in soil. In this study, the availability and mobility of silver (Ag) and gold (Au) ENPs added to agricultural soils were assessed in two separate pot experiments. Pore water samples collected from pots from day 1 to 45 using porous (<0.17 μm) membrane samplers suggest that both Ag and Au are retained almost completely within 24 h with less than 13% of the total added amount present in pore water on day 1. UV-Vis and TEM results showed that AuENPs in pore water were present as both homoaggregates and heteroaggregates until day 3 after which the concentration in pore water was too low to detect the presence of aggregates. A close relation between the concentration of Au and Fe in pore water suggests that the short term solubility of Au is partly controlled by natural soil colloids. Results suggest that under normal aerated soil conditions the actual availability of Ag and AuENPs is low which is relevant in view of risk assessment even though the impact of environmental conditions and soil properties on the reactivity of ENPs (and/or large ENPs aggregates) retained in the solid matrix need to be addressed further.

  13. Copper dynamics under alternating redox conditions is influenced by soil properties and contamination source

    NASA Astrophysics Data System (ADS)

    Balint, Ramona; Said-Pullicino, Daniel; Ajmone-Marsan, Franco

    2015-02-01

    Understanding the effect of soil redox conditions on contaminant dynamics is of significant importance for evaluating their lability, mobility and potential transfer to other environmental compartments. Under changing redox conditions, soil properties and constituents such as Fe and Mn (hydr)oxides and organic matter (OM) may influence the behavior of associated metallic elements (MEs). In this work, the redox-driven release and redistribution of Cu between different soil pools was studied in three soils having different contamination sources. This was achieved by subjecting soil columns to a series of alternating reducing and oxidizing cycles under non-limiting C conditions, and assessing their influence on soil pore water, leachate and solid phase composition. Results showed that, in all soils, alternating redox conditions led to an increase in the distribution of Cu in the more labile fractions, consequently enhancing its susceptibility to loss. This was generally linked to the redox-driven cycling of Fe, Mn and dissolved organic matter (DOM). In fact, results suggested that the reductive dissolution of Fe and Mn (hydr)oxides and subsequent reprecipitation as poorly-ordered phases under oxic conditions contributed to the release and mobilization of Cu and/or Cu-containing organometallic complexes. However, the behavior of Cu, as well as the mechanisms controlling Cu release and loss with redox cycling, was influenced by both soil properties (e.g. pH, contents of easily reducible Fe and Mn (hydr)oxides) and source of Cu contamination.

  14. Copper dynamics under alternating redox conditions is influenced by soil properties and contamination source.

    PubMed

    Balint, Ramona; Said-Pullicino, Daniel; Ajmone-Marsan, Franco

    2015-02-01

    Understanding the effect of soil redox conditions on contaminant dynamics is of significant importance for evaluating their lability, mobility and potential transfer to other environmental compartments. Under changing redox conditions, soil properties and constituents such as Fe and Mn (hydr)oxides and organic matter (OM) may influence the behavior of associated metallic elements (MEs). In this work, the redox-driven release and redistribution of Cu between different soil pools was studied in three soils having different contamination sources. This was achieved by subjecting soil columns to a series of alternating reducing and oxidizing cycles under non-limiting C conditions, and assessing their influence on soil pore water, leachate and solid phase composition. Results showed that, in all soils, alternating redox conditions led to an increase in the distribution of Cu in the more labile fractions, consequently enhancing its susceptibility to loss. This was generally linked to the redox-driven cycling of Fe, Mn and dissolved organic matter (DOM). In fact, results suggested that the reductive dissolution of Fe and Mn (hydr)oxides and subsequent reprecipitation as poorly-ordered phases under oxic conditions contributed to the release and mobilization of Cu and/or Cu-containing organometallic complexes. However, the behavior of Cu, as well as the mechanisms controlling Cu release and loss with redox cycling, was influenced by both soil properties (e.g. pH, contents of easily reducible Fe and Mn (hydr)oxides) and source of Cu contamination.

  15. Estimating steady-state evaporation rates from bare soils under conditions of high water table

    USGS Publications Warehouse

    Ripple, C.D.; Rubin, J.; Van Hylckama, T. E. A.

    1970-01-01

    A procedure that combines meteorological and soil equations of water transfer makes it possible to estimate approximately the steady-state evaporation from bare soils under conditions of high water table. Field data required include soil-water retention curves, water table depth and a record of air temperature, air humidity and wind velocity at one elevation. The procedure takes into account the relevant atmospheric factors and the soil's capability to conduct 'water in liquid and vapor forms. It neglects the effects of thermal transfer (except in the vapor case) and of salt accumulation. Homogeneous as well as layered soils can be treated. Results obtained with the method demonstrate how the soil evaporation rates·depend on potential evaporation, water table depth, vapor transfer and certain soil parameters.

  16. Improved Prediction of Quasi-Global Vegetation Conditions Using Remotely-Sensed Surface Soil Moisture

    NASA Technical Reports Server (NTRS)

    Bolten, John; Crow, Wade

    2012-01-01

    The added value of satellite-based surface soil moisture retrievals for agricultural drought monitoring is assessed by calculating the lagged rank correlation between remotely-sensed vegetation indices (VI) and soil moisture estimates obtained both before and after the assimilation of surface soil moisture retrievals derived from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) into a soil water balance model. Higher soil moisture/VI lag correlations imply an enhanced ability to predict future vegetation conditions using estimates of current soil moisture. Results demonstrate that the assimilation of AMSR-E surface soil moisture retrievals substantially improve the performance of a global drought monitoring system - particularly in sparsely-instrumented areas of the world where high-quality rainfall observations are unavailable.

  17. Bioremediation of endosulfan contaminated soil and water -- optimization of operating conditions in laboratory scale reactors.

    PubMed

    Kumar, Mathava; Philip, Ligy

    2006-08-21

    A mixed bacterial culture consisted of Staphylococcus sp., Bacillus circulans-I and -II has been enriched from contaminated soil collected from the vicinity of an endosulfan processing industry. The degradation of endosulfan by mixed bacterial culture was studied in aerobic and facultative anaerobic conditions via batch experiments with an initial endosulfan concentration of 50mg/L. After 3 weeks of incubation, mixed bacterial culture was able to degrade 71.58+/-0.2% and 75.88+/-0.2% of endosulfan in aerobic and facultative anaerobic conditions, respectively. The addition of external carbon (dextrose) increased the endosulfan degradation in both the conditions. The optimal dextrose concentration and inoculum size was estimated as 1g/L and 75mg/L, respectively. The pH of the system has significant effect on endosulfan degradation. The degradation of alpha endosulfan was more compared to beta endosulfan in all the experiments. Endosulfan biodegradation in soil was evaluated by miniature and bench scale soil reactors. The soils used for the biodegradation experiments were identified as clayey soil (CL, lean clay with sand), red soil (GM, silty gravel with sand), sandy soil (SM, silty sand with gravel) and composted soil (PT, peat) as per ASTM (American society for testing and materials) standards. Endosulfan degradation efficiency in miniature soil reactors were in the order of sandy soil followed by red soil, composted soil and clayey soil in both aerobic and anaerobic conditions. In bench scale soil reactors, endosulfan degradation was observed more in the bottom layers. After 4 weeks, maximum endosulfan degradation efficiency of 95.48+/-0.17% was observed in red soil reactor where as in composted soil-I (moisture 38+/-1%) and composted soil-II (moisture 45+/-1%) it was 96.03+/-0.23% and 94.84+/-0.19%, respectively. The high moisture content in compost soil reactor-II increased the endosulfan concentration in the leachate. Known intermediate metabolites of

  18. Soil heating and evaporation under extreme conditions: Forest fires and slash pile burns

    NASA Astrophysics Data System (ADS)

    Massman, W. J.

    2011-12-01

    Heating any soil during a sufficiently intense wild fire or prescribed burn can alter soil irreversibly, resulting in many significant and well known, long term biological, chemical, and hydrological effects. To better understand how fire impacts soil, especially considering the increasing probability of wildfires that is being driven by climate change and the increasing use of prescribe burns by land managers, it is important to better understand the dynamics of the coupled heat and moisture transport in soil during these extreme heating events. Furthermore, improving understanding of heat and mass transport during such extreme conditions should also provide insights into the associated transport mechanisms under more normal conditions as well. Here I describe the development of a new model designed to simulate soil heat and moisture transport during fires where the surface heating often ranges between 10,000 and 100,000 Wm-2 for several minutes to several hours. Model performance is tested against laboratory measurements of soil temperature and moisture changes at several depths during controlled heating events created with an extremely intense radiant heater. The laboratory tests employed well described soils with well known physical properties. The model, on the other hand, is somewhat unusual in that it employs formulations for temperature dependencies of the soil specific heat, thermal conductivity, and the water retention curve (relation between soil moisture and soil moisture potential). It also employs a new formulation for the surface evaporation rate as a component of the upper boundary condition, as well as the Newton-Raphson method and the generalized Thomas algorithm for inverting block tri-diagonal matrices to solve for soil temperature and soil moisture potential. Model results show rapid evaporation rates with significant vapor transfer not only to the free atmosphere above the soil, but to lower depths of the soil, where the vapor re

  19. Influence of sea salts on drainage water and soil chemistry of two different soil types: soil leaching experiments under laboratory conditions.

    PubMed

    Sariyildiz, Temel

    2004-07-01

    The effects of sea-salt on drainage water and soil chemistry was studied using two different soil types and setting up five soil-leaching experiments under controlled laboratory conditions. The objectives of the soil-leaching experiments were to provide information of the variability of soils and their drainage water chemistry following the input of different sea-salt solutions with different times which was similar to the precipitation input experienced during the storms in fields. Analyses were presented of major ions (Na+, Ca2+, Mg2+, Cl-, NO3-, SO4(2-) and NH4+) and pH for drainage water. At the end of the experiment, CEC (cation exchange capacity), %BS (percent base saturation), exchangeable capacity of Na, Ca and Mg and pH were also analysed for soil horizon chemistry. The results showed an increase in concentration of most of the major ions in the drainage water, though some adsorption of Na, Ca and Mg had taken place; so the result being a significant decrease in soil water pH. The chemical characteristics of each soil horizons also showed significant changes with the sea-salt applications compared to initial chemical characteristics. However, comparison of data from the four different sea-salt applications under different soil type or land-use didn't indicate the additional role that different land management could play in drainage water or soil chemistry.

  20. Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils

    NASA Astrophysics Data System (ADS)

    Sauerwein, Meike; Hanke, Alexander; Kaiser, Klaus; Kalbitz, Karsten

    2010-05-01

    Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils Meike Sauerwein1, Alexander Hanke2, Klaus Kaiser3, Karsten Kalbitz2 1) Dept. of Soil Ecology, Bayreuth Centre of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440 Bayreuth, Germany, meike.sauerwein@gmail.com 2) Institute of ecosystem dynamics and biodiversity, University of Amsterdam, 1018 WV, Netherlands, a.hanke@uva.nl, k.kalbitz@uva.nl 3) Soil Sciences, Martin Luther University Halle, 06099 Halle, Germany, klaus.kaiser@landw.uni-halle.de Current knowledge on dissolved organic matter (DOM) in soils is based mainly on observations and experiments in aerobic environments. Adsorption to soil minerals is an important mechanism of DOM retention and stabilization against microbial decay under oxic conditions. Under anoxic conditions where hydrous iron oxides, the potential main adsorbents of DOM, possibly dissolve, the importance of adsorption seems questionable. Therefore, we studied the adsorption of DOM to selected soil minerals and to mineral soils under oxic and anoxic conditions. In detail, we tested the following hypotheses: 1. Minerals and soils adsorb less DOM under anoxic conditions than under oxic ones. 2. The reduced adsorption under anoxic conditions is result of the smaller adsorption to hydrous Fe oxides whereas adsorption to clay minerals and Al hydroxides is not sensitive to changes in redox conditions 3. DOM adsorption will increase with the number of redox cycles, thus time of soil formation, due to increasing contents of poorly crystalline Fe oxides. This will, however, cause a stronger sensitivity to redox changes as poor crystalline Fe oxides are more reactive. 4. Aromatic compounds, being preferentially adsorbed under oxic conditions, will be less strongly adsorbed under anoxic conditions. We chose paddy soils as models because their periodically and regular exposure to changing redox cycles, with

  1. Load dissipation by corn residue on tilled soil in laboratory and field-wheeling conditions.

    PubMed

    Reichert, José M; Brandt, André A; Rodrigues, Miriam F; Reinert, Dalvan J; Braida, João A

    2016-06-01

    Crop residues may partially dissipate applied loads and reduce soil compaction. We evaluated the effect of corn residue on energy-applied dissipation during wheeling. The experiment consisted of a preliminary laboratory test and a confirmatory field test on a Paleaudalf soil. In the laboratory, an adapted Proctor test was performed with three energy levels, with and without corn residue. Field treatments consisted of three 5.1 Mg tractor wheeling intensities (0, 2, and 6), with and without 12 Mg ha(-1) corn residue on the soil surface. Corn residue on the soil surface reduced soil bulk density in the adapted Proctor test. By applying energy of 52.6 kN m m(-3) , soil dissipated 2.98% of applied energy, whereas with 175.4 kN m m(-3) a dissipation of 8.60% was obtained. This result confirms the hypothesis that surface mulch absorbs part of the compaction effort. Residue effects on soil compaction observed in the adapted Proctor test was not replicated under subsoiled soil field conditions, because of differences in applied pressure and soil conditions (structure, moisture and volume confinement). Nevertheless, this negative result does not mean that straw has no effect in the field. Such effects should be measured via stress transmission and compared to soil load-bearing capacity, rather than on bulk deformations. Wheeling by heavy tractor on subsoiled soil increased compaction, independently of surface residue. Two wheelings produced a significantly increase, but six wheelings did not further increase compaction. Reduced traffic intensity on recently tilled soil is necessary to minimize soil compaction, since traffic intensity show a greater effect than surface mulch on soil protection from excessive compaction. © 2015 Society of Chemical Industry. PMID:26304050

  2. Characterising soil surface condition and carbon vulnerability using spatial statistics and directional reflectance

    NASA Astrophysics Data System (ADS)

    Croft, H.; Anderson, K.

    2008-12-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of Soil Organic Matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to soil organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness, indicating that a physical soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Remotely sensed data can provide a cost- effective means of monitoring changes in soil surface condition over broad spatial extents. Growing recognition of the importance of the directional reflectance domain has highlighted their potential application for monitoring changes in soil surface roughness, associated with the breakdown of macro-aggregates and therefore SOM release. This is particularly relevant for soil condition monitoring because during soil structural degradation, changes in the self-shadowing effects of soil aggregates has a measurable effect on directional reflectance factors measured by proximal remote sensing devices. Field and laboratory data are therefore required for an empirical understanding of soil directional reflectance, underpinning subsequent model development. This experiment details the use of hyperspectral multiple view angle, proximal reflectance data (400-2500 nm) for describing changes in soil surface structure. Five different soil crusting states were produced, simulating a progressive decline in soil surface structure using artificial rainfall. Each stage was characterised using a close-range laser scanning device with a 2 mm spatial sampling methodology. Data were analysed within a geostatistical framework, where variogram analysis quantitatively confirmed the change in soil surface structure during crusting (sill variance = 0

  3. Palynofacial analysis in alkaline soils and paleoenvironmental implications: The Paso Otero 5 archaeological site (Necochea district, Buenos Aires province, Argentina)

    NASA Astrophysics Data System (ADS)

    Grill, S.; Borromei, A.; Martínez, G.; Gutierrez, M. A.; Cornou, M. E.; Olivera, D.

    2007-06-01

    The combination of palynofacial and sedimentological analyses constitutes a valuable method for paleoenvironmental and paleoclimatic reconstructions, especially when fossil pollen information is scarce or absent. This methodology elucidates a late Pleistocene/Holocene sequence at the Paso Otero 5 archaeological site in the middle basin of the Quequén Grande River, Necochea district, Buenos Aires province, Argentina. Although the main factor responsible for the destruction of pollen grains is pH, biochemical and chemical oxidation and mechanical damage contribute to the deterioration as well. The site sequence indicates that extremely arid climatic conditions without vegetation cover prevailed during the late Pleistocene (˜12,000 14C yr BP), after which the climate changed to semiarid conditions associated with a disturbed environment due to strong eolian activity (Palynofacies 1 and 2; pre-10,400 14C yr BP). During the Pleistocene/Holocene transition (Palynofacies 3 and 4; ˜10,400-9400 14C yr BP), loamy facies associated with paleosoils reflected stable conditions and temporary ponds (spring deposits). Similar conditions occurred near the end of early Holocene (Palynofacies 5-9; ˜9400-6600 14C yr BP), whereas sandy and silty facies are associated with the flood margins of streams or rivers in the middle and late Holocene (Palynofacies 10-14; 6600-2500 14C yr BP). The top of the sequence (Palynofacies 15 and 16) consists of alluvium sediments and reflects locally humid conditions and modern vegetation with anthropic influence. One of the earliest Pampean sites with evidence of humans (10,450-10,200 14C yr BP), Paso Otero 5, provides a variety of megafauna bone specimens associated with ``fish-tail" projectile points, a lithic artifact diagnostic of early human occupations in South America. The site contains a complete stratigraphic record from the late Pleistocene to the present. The evidence presented herein supports the hypothesis that human colonization, at

  4. Soil transport parameters of potassium under a tropical saline soil condition using STANMOD

    NASA Astrophysics Data System (ADS)

    Suzanye da Silva Santos, Rafaelly; Honorio de Miranda, Jarbas; Previatello da Silva, Livia

    2015-04-01

    Environmental responsibility and concerning about the final destination of solutes in soil, so more studies allow a better understanding about the solutes behaviour in soil. Potassium is a macronutrient that is required in high concentrations, been an extremely important nutrient for all agricultural crops. It plays essential roles in physiological processes vital for plant growth, from protein synthesis to maintenance of plant water balance, and is available to plants dissolved in soil water while exchangeable K is loosely held on the exchange sites on the surface of clay particles. K will tend to be adsorbed onto the surface of negatively charged soil particles. Potassium uptake is vital for plant growth but in saline soils sodium competes with potassium for uptake across the plasma membrane of plant cells. This can result in high Na+:K+ ratios that reduce plant growth and eventually become toxic. This study aimed to obtain soil transport parameters of potassium in saline soil, such as: pore water velocity in soil (v), retardation factor (R), dispersivity (λ) and dispersion coefficient (D), in a disturbed sandy soil with different concentrations of potassium chlorate solution (KCl), which is one of the most common form of potassium fertilizer. The experiment was carried out using soil samples collected in a depth of 0 to 20 cm, applying potassium chlorate solution containing 28.6, 100, 200 and 500 mg L-1 of K. To obtain transport parameters, the data were adjusted with the software STANMOD. At low concentrations, interaction between potassium and soil occur more efficiently. It was observed that only the breakthrough curve prepared with solution of 500 mg L-1 reached the applied concentration, and the solution of 28.6 mg L-1 overestimated the parameters values. The STANMOD proved to be efficient in obtaining potassium transport parameters; KCl solution to be applied should be greater than 500 mg L-1; solutions with low concentrations tend to overestimate

  5. Enhanced transformation of diphenylarsinic acid in soil under sulfate-reducing conditions.

    PubMed

    Guan, Ling; Hisatomi, Shihoko; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2012-11-30

    Diphenylarsinic acid (DPAA) is known to be the major contaminant in soils where diphenylchloroarsine and diphenylcyanoarsine were abandoned after World Wars I and II. In this study, experimental model studies were performed to elucidate key factors regulating the transformation of DPAA under anaerobic soil conditions. The elimination of DPAA in Gleysol soils (Qiqihar and Shindori soils) was more rapid than in Mollisol and Regosol soils (Heihe and Ikarashi soils, respectively) during a 5-week incubation. No clear relationship between decreasing rates of DPAA concentrations and soil Eh values was found. The Ikarashi soil showed the slowest decrease in DPAA concentrations among the four soils, but the transformation of DPAA was notably enhanced by addition of exogenous sulfate together with acetate, cellulose or rice straw. Addition of molybdate, a specific inhibitor of sulfate reduction, resulted in the stagnation of DPAA transformation, suggesting that indigenous sulfate reducers play a role in DPAA transformation under anaerobic conditions. Arsenate, phenylarsonic acid, phenylmethylarsinic acid, diphenylmethylarsine oxide and three unknown compounds were detected as metabolites of DPAA. This is the first study to reveal enhancement of DPAA transformation under sulfate-reducing conditions. PMID:23069334

  6. Bioavailability of freshly added and aged naphthalene in soils under gastric pH conditions

    SciTech Connect

    Jin, Z.; Simkins, S.; Xing, B.

    1999-12-01

    The bioavailability of hydrophobic organic chemicals decreases with aging in soil because of sequestration. However, assessments of the risk of exposure to contaminated soils are usually dependent on either chemical concentrations, which are measured using vigorous extraction methods, or models that assume an equilibrium without considering the actual conditions. The objective of this research was to determine the availability and desorption kinetics of freshly added and aged naphthalene from a peat and a mineral soil; naphthalene was desorbed into solutions with pH levels that approximate those found in different gastric regions. Soil and peat samples were spiked with radiolabeled and unlabeled naphthalene at 2 and 20 {micro}g/g and were aged from 0 to 135 d. Desorption kinetics were determined using a simulated stomach solution and a neutral solution that represented the pH of intestinal conditions and most soils. Peat sorbed much more naphthalene than did soil, and it allowed little desorption. Though both acidic and neutral extracting solutions could desorb naphthalene, little apparent effect of aging was observed in peat, whereas desorption from soil declined markedly with aging. In addition, the percentage of naphthalene that desorbed from soil was greater for the higher incubation concentration. The desorption of naphthalene from the peat and soil was higher into the neutral solution than into the gastric solution. These results suggest that aging, exposure conditions, concentration effect, and organic matter content should be taken into account in predictive models and risk assessments.

  7. Enhanced reductive dechlorination of tetrachloroethene by nano-sized mackinawite with cyanocobalamin in a highly alkaline condition.

    PubMed

    Kim, Sangwoo; Park, Taehyung; Lee, Woojin

    2015-03-15

    In this study, we characterize the reductive dechlorination of tetrachloroethene (PCE) by nano-sized mackinawite (nFeS) with cobalamin (Cbl(III)) at a high pH and investigate the effects of environmental factors, including the concentrations of the target contaminant, reductant, and catalyst and suspension ions on the dechlorination kinetics of PCE. Ninety five percent of the PCE was degraded by nFeS with Cbl(III) in 15 h. Cyclic voltammetry conducted with regard to the reductive dechlorination showed a higher redox potential of mackinawite under a high-pH condition (-1.01 V), suggesting that the oxidation state of the central cobalt ion in the cobalamin could be reduced to Cbl(I). The change of cobalamin species on the nFeS surface was verified under different pH conditions by UV-vis spectroscopy. The rate constant of PCE dechlorination increased from 0.1582 to 0.4284 h(-1) due to the increase in the nFeS content (2.085-20.85 g/L). As the concentration of Cbl(III) increased from 0 to 0.5 mM, the dechlorination kinetics of PCE was accelerated (0-1.4091 h(-1)) but reached a state of equilibrium from 0.5 to 1 mM. The increase in the initial PCE concentration (0.035-1.0 mM) slowed down the dechlorination kinetics (0.2036-0.0962 h(-1)). The dechlorination kinetics was enhanced by 1.5-11 times when 10 mM of ions (Na(+), K(+), Mg(2+), Ca(2+), CO3(2-), SO4(2-), and NO3(-)) were added, while an addition of HCO3 decelerated it by 10 times. This study can provide background knowledge pertaining to the PCE dechlorination by a natural reductant under a high-pH condition and the effect of environmental factors on the dechlorination kinetics for the development of novel remediation technologies.

  8. Forest soil respiration rate and delta13C is regulated by recent above ground weather conditions.

    PubMed

    Ekblad, Alf; Boström, Björn; Holm, Anders; Comstedt, Daniel

    2005-03-01

    Soil respiration, a key component of the global carbon cycle, is a major source of uncertainty when estimating terrestrial carbon budgets at ecosystem and higher levels. Rates of soil and root respiration are assumed to be dependent on soil temperature and soil moisture yet these factors often barely explain half the seasonal variation in soil respiration. We here found that soil moisture (range 16.5-27.6% of dry weight) and soil temperature (range 8-17.5 degrees C) together explained 55% of the variance (cross-validated explained variance; Q2) in soil respiration rate (range 1.0-3.4 micromol C m(-2) s(-1)) in a Norway spruce (Picea abies) forest. We hypothesised that this was due to that the two components of soil respiration, root respiration and decomposition, are governed by different factors. We therefore applied PLS (partial least squares regression) multivariate modelling in which we, together with below ground temperature and soil moisture, used the recent above ground air temperature and air humidity (vapour pressure deficit, VPD) conditions as x-variables. We found that air temperature and VPD data collected 1-4 days before respiration measurements explained 86% of the seasonal variation in the rate of soil respiration. The addition of soil moisture and soil temperature to the PLS-models increased the Q2 to 93%. delta13C analysis of soil respiration supported the hypotheses that there was a fast flux of photosynthates to root respiration and a dependence on recent above ground weather conditions. Taken together, our results suggest that shoot activities the preceding 1-6 days influence, to a large degree, the rate of root and soil respiration. We propose this above ground influence on soil respiration to be proportionally largest in the middle of the growing season and in situations when there is large day-to-day shifts in the above ground weather conditions. During such conditions soil temperature may not exert the major control on root respiration. PMID

  9. Stress, deformation and micromorphological aspects of soil freezing under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Jetchick, Elizabeth

    In this thesis, frost heave is viewed as a process resulting from the interactions between thermodynamic conditions, soil environment controls such as texture, stress/deformation conditions and soil microstructure. A series of laboratory experiments was devised to investigate the links between these aspects. Because a limited number of studies exist on the development of internal stresses and strains in freezing soil, the work focussed on obtaining rheological data using conventional soil strain gauges and prototype stress transducers. A fine-grained unstructured silt was placed in a column (30 cm diameter by 100 cm length) and subjected to freezing and freeze-thaw cycles from the top down, lasting up to three months. Heat and water flows, as well as stresses and strains were monitored. The frozen soil was sectioned at the end of four of the experiments to examine the soil fabrics that had developed. From the experimental results, schematic stress and strain curves are proposed. For a single freeze cycle, compressive normal and tensile normal stresses were recorded simultaneously by the measuring devices within the freezing soil profile. Ice lens inception took place when the stress field changed, a condition which occurred either at the frost front level or at the base of the growing ice lens. Negative and positive strains reflected the different stress states that were sustained below and above the freezing front. Negative strains or soil consolidation took place as stresses increased before the passage of the frost line. Negligible soil strains were recorded as maximum soil consolidation was attained, before soil expansion. Distinct positive strain patterns indicating secondary and continuing heave, were recorded simultaneously throughout a thickness of soil, over a range of temperatures. Ice lens growth mostly took place as secondary frost heave, but continuing heave was measured, and the temperature conditions for both types of heave were determined. During

  10. Positive responses of coastal dune plants to soil conditioning by the invasive Lupinus nootkatensis

    NASA Astrophysics Data System (ADS)

    Hanslin, Hans Martin; Kollmann, Johannes

    2016-11-01

    Invasive nitrogen-fixing plants drive vegetation dynamics and may cause irreversible changes in nutrient-limited ecosystems through increased soil resources. We studied how soil conditioning by the invasive alien Lupinus nootkatensis affected the seedling growth of co-occurring native plant species in coastal dunes, and whether responses to lupin-conditioned soil could be explained by fertilisation effects interacting with specific ecological strategies of the native dune species. Seedling performance of dune species was compared in a greenhouse experiment using field-collected soil from within or outside coastal lupin stands. In associated experiments, we quantified the response to nutrient supply of each species and tested how addition of specific nutrients affected growth of the native grass Festuca arundinacea in control and lupin-conditioned soil. We found that lupin-conditioned soil increased seedling biomass in 30 out of 32 native species; the conditioned soil also had a positive effect on seedling biomass of the invasive lupin itself. Increased phosphorus mobilisation by lupins was the major factor driving these positive seedling responses, based both on growth responses to addition of specific elements and analyses of plant available soil nutrients. There were large differences in growth responses to lupin-conditioned soil among species, but they were unrelated to selected autecological indicators or plant strategies. We conclude that Lupinus nootkatensis removes the phosphorus limitation for growth of native plants in coastal dunes, and that it increases cycling of other nutrients, promoting the growth of its own seedlings and a wide range of dune species. Finally, our study indicates that there are no negative soil legacies that prevent re-establishment of native plant species after removal of lupins.

  11. Effect of phosphoric fertilizer and starter rates of nitrogen fertilizers on the phosphatase activity in the rhizosphere soil and nonlignified soybean roots under drought conditions

    NASA Astrophysics Data System (ADS)

    Emnova, E. E.; Daraban, O. V.; Bizgan, I. V.; Toma, S. I.

    2014-02-01

    In a small-plot field experiment, two soybean ( Glycine max L.) cultivars were grown on a calcareous chernozem under the drought conditions of 2012 with the preplanting application of simple superphosphate (Ps) at 60 kg/ha, urea (Nu) at 10 and 20 kg/ha, and ammonium nitrate (Nan) at 20 kg/ha. The phosphatase activity was measured in the rhizosphere soil (0- to 20-cm layer) and the fine nonlignified roots of soybean plants at the blossoming and pod-formation stages (the soil water content was 19 and 33% of the total water capacity, respectively). The maximum content of available phosphorus in the rhizosphere of both soybean cultivars (4.3-4.8 mg/100 g dry soil) was found at the simultaneous application of Ps and Nu20. Higher activities of the predominant phosphatases (alkaline phosphatase in the rhizosphere and acid phosphatase in the roots) were observed in the root-inhabited zone of the soil under the Indra cultivar compared to the Aura cultivar, which correlated with the lower content of available phosphorus in the rhizosphere soil (especially at the simultaneous application of Ps and Nu20) and the higher productivity of this cultivar in this treatment.

  12. Soil conditions and cereal root system architecture: review and considerations for linking Darwin and Weaver.

    PubMed

    Rich, Sarah M; Watt, Michelle

    2013-03-01

    Charles Darwin founded root system architecture research in 1880 when he described a root bending with gravity. Curving, elongating, and branching are the three cellular processes in roots that underlie root architecture. Together they determine the distribution of roots through soil and time, and hence the plants' access to water and nutrients, and anchorage. Most knowledge of these cellular processes comes from seedlings of the model dicotyledon, Arabidopsis, grown in soil-less conditions with single treatments. Root systems in the field, however, face multiple stimuli that interact with the plant genetics to result in the root system architecture. Here we review how soil conditions influence root system architecture; focusing on cereals. Cereals provide half of human calories, and their root systems differ from those of dicotyledons. We find that few controlled-environment studies combine more than one soil stimulus and, those that do, highlight the complexity of responses. Most studies are conducted on seedling roots; those on adult roots generally show low correlations to seedling studies. Few field studies report root and soil conditions. Until technologies are available to track root architecture in the field, soil analyses combined with knowledge of the effects of factors on elongation and gravitropism could be ranked to better predict the interaction between genetics and environment (G×E) for a given crop. Understanding how soil conditions regulate root architecture can be effectively used to design soil management and plant genetics that best exploit synergies from G×E of roots.

  13. Uranium partitioning under acidic conditions in a sandy soil aquifer

    SciTech Connect

    Johnson, W.H. |; Serkiz, S.M.; Johnson, L.M.

    1995-07-01

    The partitioning of uranium in an aquifer down gradient of two large mixed waste sites was examined with respect to the solution and soil chemistry (e.g., pH redox potential and contaminant concentration) and aqueous-phase chemical speciation. This involved generation of field-derived, batch sorption, and reactive mineral surface sorption data. Field-derived distribution coefficients for uranium at these waste sites were found to vary between 0.40 and 15,000. Based on thermodynamic speciation modeling and a comparison of field and laboratory data, gibbsite is a potential reactive mineral surface present in modified soils at the sites. Uranium partitioning data are presented from field samples and laboratory studies of background soil and the mineral surface gibbsite. Mechanistic and empirical sorption models fit to the field-derived uranium partitioning data show an improvement of over two orders of magnitude, as measured by the normalized sum of errors squared, when compared with the single K{sub d} model used in previous risk work. Models fit to batch sorption data provided a better fit of sorbed uranium than do models fit to the field-derived data.

  14. Breaking The Enzymatic Latch: Do Anaerobic Conditions Constrain Decomposition In Humid Tropical Forest Soil?

    NASA Astrophysics Data System (ADS)

    Hall, S. J.; Silver, W. L.

    2011-12-01

    Anaerobic conditions have been proposed to impose a "latch" on soil organic matter decomposition by inhibiting the activity of extracellular enzymes that catalyze the transformation of organic polymers into monomers for microbial assimilation. Here, we tested the hypothesis that anaerobiosis inhibits soil hydrolytic enzyme activity in a humid tropical forest ecosystem in Puerto Rico. We sampled surface and sub-surface soil from each of 59 plots (n = 118) stratified across distinct topographical zones (ridges, slopes, and valleys) known to vary in soil oxygen (O2) concentrations, and measured the potential activity of five hydrolytic enzymes that decompose carbon (C), nitrogen (N), and phosphorus (P) substrates. We measured reduced iron (Fe (II)) concentrations in soil extractions to provide a spatially and temporally integrated index of anaerobic microbial activity, since iron oxides constitute the dominant anaerobic terminal electron acceptor in this ecosystem. Surprisingly, we observed positive relationships between Fe (II) concentrations and the activity of all enzymes that we assayed. Linear mixed effects models that included Fe (II) concentration, topographic position, and their interaction explained between 30 to 70 % of the variance of enzyme activity of β-1,4-glucosidase, β-cellobiohydrolase, β-xylosidase, N-acetylglucosaminidase, and acid phosphatase. Soils from ridges and slopes contained between 10 and 800 μg Fe (II) g-1 soil, and exhibited consistently positive relationships (p < 0.0001) between Fe (II) and enzyme activity. Valley soils did not display significant relationships between enzyme activity and Fe (II), although they displayed variation in soil Fe (II) concentrations similar to ridges and slopes. Overall, valleys exhibited lower enzyme activity and lower Fe (II) concentrations than ridges or slopes, possibly related to decreased root biomass and soil C. Our data provide no indication that anaerobiosis suppresses soil enzyme activity, but

  15. An analysis of the dissipation of pharmaceuticals under thirteen different soil conditions.

    PubMed

    Kodešová, Radka; Kočárek, Martin; Klement, Aleš; Golovko, Oksana; Koba, Olga; Fér, Miroslav; Nikodem, Antonín; Vondráčková, Lenka; Jakšík, Ondřej; Grabic, Roman

    2016-02-15

    The presence of human and veterinary pharmaceuticals in the environment is recognized as a potential threat. Pharmaceuticals have the potential to contaminate soils and consequently surface and groundwater. Knowledge of contaminant behavior (e.g., sorption onto soil particles and degradation) is essential when assessing contaminant migration in the soil and groundwater environment. We evaluated the dissipation half-lives of 7 pharmaceuticals in 13 soils. The data were evaluated relative to the soil properties and the Freundlich sorption coefficients reported in our previous study. Of the tested pharmaceuticals, carbamazepine had the greatest persistence (which was mostly stable), followed by clarithromycin, trimethoprim, metoprolol, clindamycin, sulfamethoxazole and atenolol. Pharmaceutical persistence in soils was mostly dependent on the soil-type conditions. In general, lower average dissipation half-lives and variability (i.e., trimethoprim, sulfamethoxazole, clindamycin, metoprolol and atenolol) were found in soils of better quality (well-developed structure, high nutrition content etc.), and thus, probably better microbial conditions (i.e., Chernozems), than in lower quality soil (Cambisols). The impact of the compound sorption affinity onto soil particles on their dissipation rate was mostly negligible. Although there was a positive correlation between compound dissipation half-life and Freundlich sorption coefficient for clindamycin (R=0.604, p<0.05) and sulfamethoxazole (R=0.822, p<0.01), the half-life of sulfamethoxazole also decreased under better soil-type conditions. Based on the calculated dissipation and sorption data, carbamazepine would be expected to have the greatest potential to migrate in the soil water environment, followed by sulfamethoxazole, trimethoprim and metoprolol. The transport of clindamycin, clarithromycin and atenolol through the vadose zone seems less probable.

  16. Evaluation of the efficacy of polyphosphate remediation technology: Direct and indirect remediation of uranium under alkaline conditions

    SciTech Connect

    Wellman, Dawn M.; Fruchter, Jonathan S.; Vermeul, Vincent R.; Richards, Emily L.; Jansik, Danielle P.; Edge, Ellen

    2011-08-31

    A field-scale technology demonstration has been conducted to optimize polyphosphate remediation technology for enhanced monitored natural attenuation of the uranium plume within the 300 Area aquifer at the Hanford Site, southeastern Washington State. The objective was to evaluate the efficacy of polyphosphate to treat uranium-contaminated groundwater in situ. Focused application of polyphosphate was conducted in a source or 'hot spot' area to reduce the inventory of available uranium contributing to the groundwater plume through direct precipitation of uranyl-phosphate solids and secondary containment via precipitation of apatite which can serve as a long-term sorbent for uranium. The test site consisted of an injection well and 15 monitoring wells installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. The results indicated sequestration of uranium as insoluble phosphate phases appears to be a promising alternative for treating the uranium- contaminated groundwater at the Hanford Site 300 Area. However, the formation of the apatite during the test was limited due to two separate overarching issues: (1) formation and emplacement of apatite via polyphosphate technology, and (2) efficacy of apatite for sequestering uranium under the present geochemical and hydrodynamic conditions.

  17. Manganese-oxide-coated redox bars as an indicator of reducing conditions in soils.

    PubMed

    Dorau, Kristof; Mansfeldt, Tim

    2015-03-01

    Identification of reducing conditions in soils is of concern not only for pedogenesis but also for nutrient and pollutant dynamics. We manufactured manganese (Mn)-oxide-coated polyvinyl chloride bars and proved their suitability for the identification of reducing soil conditions. Birnessite was synthesized and coated onto white polyvinyl chloride bars. The dark brown coatings were homogenous and durable. As revealed by microcosm devices with adjusted redox potentials (E), under oxidizing conditions (E ∼450 mV at pH 7) there was no Mn-oxide removal. Reductive dissolution of Mn-oxides, which is expressed by the removal of the coatings, started under weakly reducing conditions (E ∼175 mV) and was more intensive under moderately reducing conditions (∼80 mV). According to thermodynamics, the removal of Mn-oxide coatings (225 mm d) exceeded the removal of iron (Fe)-oxide coatings (118 mm d) in soil column experiments. This was confirmed in a soil with a shallow and strongly fluctuating water table where both types of redox bars were inserted. Consequently, it was possible to identify reducing conditions in soils using Mn-oxide-coated bars. We recommend this methodology for short-term monitoring because tri- and tetravalent Mn is the preferred electron acceptor compared with trivalent Fe, and this additionally offers the possibility of distinguishing between weakly and moderately reducing conditions. If dissolved Fe is abundant in soils, the possibility of nonenzymatic reduction of Mn has to be taken into account.

  18. CoxC encased in carbon nanotubes: an efficient oxygen reduction catalyst under both acidic and alkaline conditions.

    PubMed

    Chen, Lisong; Cui, Xiangzhi; Wang, Qingsong; Zhang, Xiaohua; Wan, Gang; Cui, Fangming; Wei, Chenyang; Shi, Jianlin

    2015-12-21

    The design of a non-precious metal oxygen reduction reaction (ORR) catalyst of high activity and long durability in acidic electrolyte is of great importance for the development and commercialization of low-temperature fuel cells, which remains a great challenge to date. Here, we demonstrate a facile, scalable protocol for the controlled synthesis of CoxC encapsulated in carbon nanotubes as a novel kind of efficient electrochemical oxygen reduction reaction (ORR) catalyst. The synthesized CoxC/carbon nanotube features a high BET surface area, large pore volume and high graphitic content, which greatly favors enhanced ORR properties. The resultant composite electro-catalyst shows high ORR activity which is comparable with that of 20 wt% Pt/C in 0.1 M KOH electrolyte. More importantly, it also exhibits a high ORR activity in 0.1 M HClO4 with a near-complete 4e pathway. More attractively, compared to the most investigated FexC, CoxC as the proposed main catalytically active center shows much enhanced activity in acidic electrolyte, which will pave the way towards the rational design of an advanced electro-catalyst for an efficient ORR process especially under acidic conditions. Moreover, a fuel cell using the synthesized CoxC/carbon nanotube as a cathode catalyst showed a large open-circuit potential, high output power density and long durability, which make it a promising alternative to Pt/C as a non-precious metal ORR catalyst in proton exchange membrane fuel cells. PMID:26565522

  19. CoxC encased in carbon nanotubes: an efficient oxygen reduction catalyst under both acidic and alkaline conditions.

    PubMed

    Chen, Lisong; Cui, Xiangzhi; Wang, Qingsong; Zhang, Xiaohua; Wan, Gang; Cui, Fangming; Wei, Chenyang; Shi, Jianlin

    2015-12-21

    The design of a non-precious metal oxygen reduction reaction (ORR) catalyst of high activity and long durability in acidic electrolyte is of great importance for the development and commercialization of low-temperature fuel cells, which remains a great challenge to date. Here, we demonstrate a facile, scalable protocol for the controlled synthesis of CoxC encapsulated in carbon nanotubes as a novel kind of efficient electrochemical oxygen reduction reaction (ORR) catalyst. The synthesized CoxC/carbon nanotube features a high BET surface area, large pore volume and high graphitic content, which greatly favors enhanced ORR properties. The resultant composite electro-catalyst shows high ORR activity which is comparable with that of 20 wt% Pt/C in 0.1 M KOH electrolyte. More importantly, it also exhibits a high ORR activity in 0.1 M HClO4 with a near-complete 4e pathway. More attractively, compared to the most investigated FexC, CoxC as the proposed main catalytically active center shows much enhanced activity in acidic electrolyte, which will pave the way towards the rational design of an advanced electro-catalyst for an efficient ORR process especially under acidic conditions. Moreover, a fuel cell using the synthesized CoxC/carbon nanotube as a cathode catalyst showed a large open-circuit potential, high output power density and long durability, which make it a promising alternative to Pt/C as a non-precious metal ORR catalyst in proton exchange membrane fuel cells.

  20. Changes in mineral soil biogeochemical cycling and environmental conditions following tree harvest in the Northeast

    NASA Astrophysics Data System (ADS)

    Vario, C.; Friedland, A.

    2012-12-01

    In the northeastern United States, reductions in carbon dioxide emissions have been attempted by using local wood as a renewable alternative to oil. Although woody biomass products are readily available, recent findings suggest that forest disturbance may cause release of carbon from the deeper mineral soil. Worldwide, deep soils sequester more than half of soil carbon, making it critical in the global carbon cycle; however, most studies on the effect of harvesting have focused on the organic soil horizon. Our research aimed to uncover changes in biogeochemistry and environmental conditions in deeper, mineral soil after clear cutting forests. We quantified post-harvest mineral soil carbon pools through a regional study. We utilized stands of different ages to measure the recovery of soil carbon over time since harvest. Stands included in this study were cut approximately 5, 12, 25, 50, or 120 ybp, in order to identify changes in soil carbon over time since harvest. We sampled harvested stands in six research or protected forests across New York, New Hampshire, Massachusetts, and Vermont. Soil samples were collected to a depth of 60 cm below the surface of the mineral soil using a gas-powered augur and 9.5 cm diameter drill bit. Soil samples were analyzed at Dartmouth College. In order to understand specific changes in mineral soil carbon dynamics following harvest, measurements of carbon fluxes, such as soil respiration and DOC transport were conducted at five different-aged stands at Bartlett Experimental Forest, NH. While parameters that may influence carbon storage—such as pH, clay content, tree cover and elevation— did not vary across the different-aged stands in each forest, carbon pools did vary over time. We found changes in carbon pools in at least three experimental forests across the northeast. At Bartlett Experimental Forest, we found a gradual decline in mineral soil carbon storage from between 85-87 Mg ha-1 in 120 year old and primary forest stands

  1. Soil nitrous oxide emissions under climate change in Mediterranean dryland conditions

    NASA Astrophysics Data System (ADS)

    Álvaro-Fuentes, Jorge; Arrúe, José Luis; Plaza-Bonilla, Daniel; Cantero-Martínez, Carlos

    2016-04-01

    Soils play a double role in relation with climate change. Soils have the ability to decrease atmospheric carbon dioxide concentration throughout soil carbon sequestration and, concurrently, they are also a main source of greenhouse gases. Particularly, agricultural soils are major emitters of nitrous oxide (N2O) globally. Recent outputs from general circulation models show that in the near future drought stress would be especially critical in the Mediterranean basin. These predictions could have a noteworthy impact on soil N2O emissions. Consequently, current mitigation options might be no longer valid in the near future. The main objective of this work was to determine the capability of different land uses under climate change conditions to mitigate soil N2O emissions in Mediterranean dryland agroecosystems. Soil N2O emissions were measured during 18 months (from December 2011 to June 2013) under different land uses in a typical Mediterranean agroecosystem. The observed data was used to test the ability of the Daycent model to simulate N2O emissions in dryland Mediterranean soils. Next, the model was used to predict the impact of climate change on soil N2O emissions under different land use scenarios in Mediterranean conditions.

  2. Butachlor inhibits production and oxidation of methane in tropical rice soils under flooded condition.

    PubMed

    Mohanty, S R; Nayak, D R; Babu, Y J; Adhya, T K

    2004-01-01

    In laboratory incubation experiments, application of a commercial formulation of the herbicide butachlor (N-butoxymethyl-2-chloro-2',6'-diethyl acetanilide) to three tropical rice soils, widely differing in their physicochemical characteristics, under flooded condition inhibited methane (CH4) production. The inhibitory effect was concentration dependent and most remarkable in the alluvial soil. Thus, following application of butachlor at 5, 10, 50 and 100 microg g(-1) soil, respectively, cumulative CH4 production in the alluvial soil was inhibited by 15%, 31%, 91% and 98% over unamended control. Since CH4 production was less pronounced in the sandy loam and acid sulfate soil, the impact of amendment with butchalor, albeit inhibitory, was less extensive than the alluvial soil. Inhibition of CH4 production in butachlor-amended alluvial soil was related to the prevention in the drop in redox potential as well as low methanogenic bacterial population especially at high concentrations of butachlor. CH4 oxidation was also inhibited in butachlor-amended alluvial soil with the inhibitory effect being more prevalent under flooded condition. Inhibition in CH4 oxidation was related to a reduction in the population of soluble methane monooxygenase producing methanotrophs. Results demonstrate that butachlor, a commonly used herbicide in rice cultivation, even at very low concentrations can affect CH4 production and its oxidation, thereby influencing the biogeochemical cycle of CH4 in flooded rice soils.

  3. Soil, Water, and Vegetation Conditions in South Texas

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Gausman, H. W.; Leamer, R. W.; Richardson, A. J. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. Reflectance differences between the dead leaves of six crops (corn, cotton, sorghum, sugar cane, citrus, and avocado) and the respective bare soils where the dead leaves were lying on the ground were determined from laboratory spectrophotometric measurements over the 0.5- to 2.5 micron wavelength interval. The largest differences were in the near infrared waveband 0.75- to 1.35 microns. Leaf area index was predicted from plant height, percent ground cover, and plant population for irrigated and nonirrigated grain sorghum fields for the 1975 growing season.

  4. Sensitivity of Polygonum aviculare Seeds to Light as Affected by Soil Moisture Conditions

    PubMed Central

    Batlla, Diego; Nicoletta, Marcelo; Benech-Arnold, Roberto

    2007-01-01

    Background and Aims It has been hypothesized that soil moisture conditions could affect the dormancy status of buried weed seeds, and, consequently, their sensitivity to light stimuli. In this study, an investigation is made of the effect of different soil moisture conditions during cold-induced dormancy loss on changes in the sensitivity of Polygonum aviculare seeds to light. Methods Seeds buried in pots were stored under different constant and fluctuating soil moisture environments at dormancy-releasing temperatures. Seeds were exhumed at regular intervals during storage and were exposed to different light treatments. Changes in the germination response of seeds to light treatments during storage under the different moisture environments were compared in order to determine the effect of soil moisture on the sensitivity to light of P. aviculare seeds. Key Results Seed acquisition of low-fluence responses during dormancy release was not affected by either soil moisture fluctuations or different constant soil moisture contents. On the contrary, different soil moisture environments affected seed acquisition of very low fluence responses and the capacity of seeds to germinate in the dark. Conclusions The results indicate that under field conditions, the sensitivity to light of buried weed seeds could be affected by the soil moisture environment experienced during the dormancy release season, and this could affect their emergence pattern. PMID:17430979

  5. Bioactivity of Several Herbicides on the Nanogram Level Under Different Soil Moisture Conditions.

    PubMed

    Jung, S C; Kuk, Y I; Senseman, S A; Ahn, H G; Seong, C N; Lee, D J

    2015-01-01

    In this study, a double-tube centrifuge method was employed to determine the effects of soil moisture on the bioactivity of cafenstrole, pretilachlor, benfuresate, oxyfluorfen and simetryn. In general, the available herbicide concentration in soil solution (ACSS) showed little change as soil moisture increased for herbicides. The total available herbicide in soil solution (TASS) typically increased as soil moisture increased for all herbicides. The relationship between TASS and % growth rate based on dry weight showed strong linear relationships for both cafenstrole and pretilachlor, with r2 values of 0.95 and 0.84, respectively. Increasing TASS values were consistent with increasing herbicide water solubility, with the exception of the ionizable herbicide simetryn. Plant absorption and % growth rate exhibited a strong linear relationship with TASS. According to the results suggested that TASS was a better predictor of herbicidal bioactivity than ACSS for all herbicides under unsaturated soil moisture conditions. PMID:26328425

  6. Bioactivity of Several Herbicides on the Nanogram Level Under Different Soil Moisture Conditions.

    PubMed

    Jung, S C; Kuk, Y I; Senseman, S A; Ahn, H G; Seong, C N; Lee, D J

    2015-01-01

    In this study, a double-tube centrifuge method was employed to determine the effects of soil moisture on the bioactivity of cafenstrole, pretilachlor, benfuresate, oxyfluorfen and simetryn. In general, the available herbicide concentration in soil solution (ACSS) showed little change as soil moisture increased for herbicides. The total available herbicide in soil solution (TASS) typically increased as soil moisture increased for all herbicides. The relationship between TASS and % growth rate based on dry weight showed strong linear relationships for both cafenstrole and pretilachlor, with r2 values of 0.95 and 0.84, respectively. Increasing TASS values were consistent with increasing herbicide water solubility, with the exception of the ionizable herbicide simetryn. Plant absorption and % growth rate exhibited a strong linear relationship with TASS. According to the results suggested that TASS was a better predictor of herbicidal bioactivity than ACSS for all herbicides under unsaturated soil moisture conditions.

  7. Effect of soil surface conditions on runoff velocity and sediment mean aggregate diameter

    NASA Astrophysics Data System (ADS)

    César Ramos, Júlio; Bertol, Ildegardis; Paz González, Antonio; de Souza Werner, Romeu; Marioti, Juliana; Henrique Bandeira, Douglas; Andrighetti Leolatto, Lidiane

    2013-04-01

    Soil cover and soil management are the factors that most influence soil erosion by water, because they directly affect soil surface roughness and surface cover. The main effect of soil cover by crop residues consists in dissipation of kinetic energy of raindrops and also partly kinetic energy of runoff, so that the soil disaggregation is considerably reduced but, in addition, soil cover captures detached soil particles, retains water on its surface and decreases runoff volume and velocity. In turn, soil surface roughness, influences soil surface water storage and infiltration and also runoff volume and velocity, sediment retention and subsequently water and sediment losses. Based on the above rationale, we performed a field experiment to assess the influence of soil cover and soil surface roughness on decay of runoff velocity as well as on mean diameter of transported sediments (D50 index). The following treatments were evaluated: SRR) residues of Italian ryegrass (Lolium multiflorum) on a smooth soil surfcace, SRV) residues of common vetch (Vicia sativa) on a smooth soil surface, SSR) scarification after cultivation of Italian ryegrass resulting in a rough surface, SSV) scarification after cultivation of common vetch resulting in a rough surface, and SBS) scarified bare soil with high roughness as a control. The field experiments was performed on an Inceptisol in South Brazil under simulated rainfall conditions during 2012. Experimental plots were 11 m long and 3.5 m wide with an area of 38.5 m2. Six successive simulated rainfall tests were applied using a rotating-boom rain simulator. During each test, rain intensity was 60 mmhr-1, whereas rain duration was 90 minutes. Runoff velocity showed no significant differences between cultivated treatments. However, when compared to bare soil treatment, SBS (0.178 m s-1) and irrespective of the presence of surface crop residues or scarification operations, cultivated soil treatments significantly reduced runoff velocity

  8. The soil ecotoxicology of 1,3-dichloropropene under commercial growing conditions.

    PubMed

    Small, Graham; Miles, Mark; Barber, Ian; Tsakonas, Paris; Bucchi, Renzo

    2008-01-01

    Soil fumigants are used extensively in the protection of crops against parasitic nematodes and other soil borne pests. The active ingredient in Telone II soil fumigant is 1,3-Dichloropropene (1,3-D) which has a wide range of uses in Europe as a pre-plant nematocide. During the use of soil fumigants such as 1,3-D a range of non-target soil dwelling organisms has the potential to be exposed and impacted. We report here the results of a field study conducted in Italy to assess the impact of 1,3-D applications to soil-dwelling non-target organisms. This study was conducted under conditions of commercial tomato growing either without (untreated control) or with an application of 1,3-D at 224 kg a.i./hectare. Samples of arthropods and earthworms were taken before and up to 12 months after application to measure season long effects. A soil sample was taken at 4.5 months and a soil function test performed. By evaluating the effects of 1,3-D both in the Laboratory and under field conditions equivalent to commercial practices it was concluded that applications of 1,3-D would not adversely effect soil arthropods, but may have an effect on earthworms and soil microflora. These effects were, however, transient as full recovery was observed within six months of application for earthworms and 4.5 months for soil microflora. Consequently, the risk to non-target soil micro- and macro-organisms was considered acceptable according to current risk assessment guidelines within the European Union.

  9. Effect of the irrigation with waste water on two different mediterranean soils under greenhouse conditions

    NASA Astrophysics Data System (ADS)

    Pina, S.; Garcia-Orenes, F.; Mataix, J.; Jordan, M. M.; Mataix-Solera, J.

    2009-04-01

    The semi-arid zones as the Mediterranean coast are densely populated and their aquifers are being hardly exploited. The use of waste water for irrigation is an alternative for the water shortage. Consequently, it is considered necessary to improve the efforts to investigate changes of soil properties. The main objective of this work was to compare the short-term effects of irrigation with waste water on two different Mediterranean soils. It was used flowerpots with loquat (Eriobotrya japonica Lindl) under greenhouse conditions. Two different Mediterranean soils were selected from Alicante, SE of Spain, one gypsiferous soil and one calcareous soil with similar texture, to evaluate the different behaviour against waste water irrigation. The flowerpots were irrigated with two different treatments: fresh water (control) and treated waste water from secondary treatment. The experience lasted twelve months, the first six to adapt the plants into the greenhouse and then the soils were irrigated twice a week. Two soil sampling were taking in the beginning and in the end of the experiment to determinate EC, Na, P, OC and N. In both soils our results show a slight increase in electrical conductivity, being deeper in the calcareous soil as it is easier to drain. However it was found a higher increase of sodium concentrations in the gypsiferous soil. Fertility analysis in the secondary treatment of both soils presented an improvement in potassium and available phosphorus levels. In the other hand, organic carbon and nitrogen do not seem to change; the reason could be an enhancement in biological activity caused by irrigation. This biological activity and greenhouse conditions speed up organic matter mineralization. According to the short-term results in the soils studied parameters, except for electrical conductivity and sodium content, there is not a notable negative impact. Nevertheless, it must be necessary to extend the experience for long-term conclusions.

  10. Sensitivity of soil moisture initialization for decadal predictions under different regional climatic conditions in Europe

    NASA Astrophysics Data System (ADS)

    Khodayar, S.; Sehlinger, A.; Feldmann, H.; Kottmeier, C.

    2015-12-01

    The impact of soil initialization is investigated through perturbation simulations with the regional climate model COSMO-CLM. The focus of the investigation is to assess the sensitivity of simulated extreme periods, dry and wet, to soil moisture initialization in different climatic regions over Europe and to establish the necessary spin up time within the framework of decadal predictions for these regions. Sensitivity experiments consisted of a reference simulation from 1968 to 1999 and 5 simulations from 1972 to 1983. The Effective Drought Index (EDI) is used to select and quantify drought status in the reference run to establish the simulation time period for the sensitivity experiments. Different soil initialization procedures are investigated. The sensitivity of the decadal predictions to soil moisture initial conditions is investigated through the analysis of water cycle components' (WCC) variability. In an episodic time scale the local effects of soil moisture on the boundary-layer and the propagated effects on the large-scale dynamics are analysed. The results show: (a) COSMO-CLM reproduces the observed features of the drought index. (b) Soil moisture initialization exerts a relevant impact on WCC, e.g., precipitation distribution and intensity. (c) Regional characteristics strongly impact the response of the WCC. Precipitation and evapotranspiration deviations are larger for humid regions. (d) The initial soil conditions (wet/dry), the regional characteristics (humid/dry) and the annual period (wet/dry) play a key role in the time that soil needs to restore quasi-equilibrium and the impact on the atmospheric conditions. Humid areas, and for all regions, a humid initialization, exhibit shorter spin up times, also soil reacts more sensitive when initialised during dry periods. (e) The initial soil perturbation may markedly modify atmospheric pressure field, wind circulation systems and atmospheric water vapour distribution affecting atmospheric stability

  11. Identification of a novel carotenoid, 2'-isopentenylsaproxanthin, by Jejuia pallidilutea strain 11shimoA1 and its increased production under alkaline condition.

    PubMed

    Takatani, N; Nishida, K; Sawabe, T; Maoka, T; Miyashita, K; Hosokawa, M

    2014-08-01

    Carotenoids are a class of naturally occurring pigment, carrying out important biological functions in photosynthesis and involved in environmental responses including nutrition in organisms. Saproxanthin and myxol, which have monocyclic carotenoids with a γ-carotene skeleton, have been reported to show a stronger antioxidant activity than those with β-carotene and zeaxanthin. In this research, a yellow-orange bacterium of strain 11shimoA1 (JCM19538) was isolated from a seaweed collected at Nabeta Bay (Shizuoka, Japan). The 16S rRNA gene sequence of strain 11shimoA1 revealed more than 99.99 % similarity with those of Jejuia pallidilutea strains in the family Flavobacteriaceae. Strain 11shimoA1 synthesized two types of carotenoids. One of them was (3R, 3'R)-zeaxanthin with dicyclic structure and another was identified as (3R, 2'S)-2'-isopentenylsaproxanthin, a novel monocyclic carotenoid with pentenyl residue at C-2' position of saproxanthin, using FAB-MS, (1)H NMR, and CD analyses. Culturing strain 11shimoA1 in an alkaline medium at pH 9.2 resulted in a markedly increased in production of 2'-isopentenylsaproxanthin per dry cell weight, but a decreased in zeaxanthin production as compared to their respective production levels in medium with pH 7.0. These carotenoids are likely to play some roles in the adaptation of the bacterium to the environmental conditions. PMID:24723292

  12. Preparation in Acidic and Alkaline Conditions and Characterization of α-Bi2Mo3O12 and γ-Bi2MoO6 Powders

    NASA Astrophysics Data System (ADS)

    Chen, Tao; Wang, Mao-Hua; Ma, Xiao-Yu

    2016-08-01

    α-Bi2Mo3O12 and γ-Bi2MoO6 powders have been successfully fabricated via a sol-gel method starting from bismuth nitrate and ammonium molybdate. The as-synthesized samples were characterized by x-ray powder diffraction analysis, thermogravimetry and differential thermogravimetry, scanning electron microscopy, and ultraviolet-visible (UV-Vis) absorption spectroscopy. The results indicated the formation of α-Bi2Mo3O12 and γ-Bi2MoO6 powders in acidic (pH 5) and alkaline (pH 9) conditions, respectively. α-Bi2Mo3O12 exhibited irregular shape, while γ-Bi2MoO6 showed approximately flake-like morphology. The bandgap of pure α-Bi2Mo3O12 and γ-Bi2MoO6 was estimated to be about 2.83 eV and 2.85 eV, respectively, according to UV-Vis studies. The slight shift of the absorption edge towards longer wavelength for α-Bi2Mo3O12 indicated a decrease of the optical bandgap. Photocatalytic experiments showed that γ-Bi2MoO6 exhibited higher photodegradation activity of methylene blue compared with α-Bi2Mo3O12.

  13. Influences of solution chemical conditions on mobilization of TNT from contaminated soil

    SciTech Connect

    Dante, D.A.; Tiller, C.L.; Pennell, K.D.

    1996-12-31

    2,4,6-trinitrotoluene (TNT) and its byproducts are common contaminants on US military installations. Many potential remediation processes are in part limited by the transfer of TNT from the contaminated soil into the aqueous phase. The purpose of this research is to assess the release of TNT from contaminated soil under varying solution chemical conditions. In particular, influences of pH, aquatic natural organic matter, and addition of two surfactants is investigated. Uncontaminated soil was collected from a near-surface site at the Alabama Army Ammunition Plant and was artificially contaminated with TNT prior to the mobilization experiments. Results for the pH experiments show that more TNT is mobilized at neutral pH conditions than at low pH conditions. The presence of dissolved organic matter enhances the release of TNT from soil, but not by a large amount. Surfactant addition has the most significant effect on TNT mobilization.

  14. Soil, water, and vegetation conditions in south Texas

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Gausman, H. W.; Leamer, R. W.; Richardson, A. J.; Everitt, J. H.; Gerbermann, A. H. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. Field spectral measurements and laboratory densitometric measurements showed that tree canopy reflectance differences among the Marrs, Redblush, and Valencia varieties in the visible spectral region were due to their different leaf chlorophyll concentrations. Field measurements of visible light reflectance were directly related to the tonal responses on infrared color photos of the varietal tree canopies. Consequently, densitometric measurements of the foliage on the infrared color transparency with red-filtered light successfully discriminated among the three varieties. Reflectance measurements with a field spectroradiometer on nine dates the growing season of two wheat varieties, Milam and Penjamo, documented their spectra over the 0.45 to 2.50 micron wavelength interval associated with plant cover and physiological development. An image analyzer system was used to optically planimeter the percentage of soil background, vegetation and shadow in the vertical photographs taken within the FOV of the spectroradiometer on each measurement date.

  15. Modeling soil heating and moisture transport under extreme conditions: Forest fires and slash pile burns

    NASA Astrophysics Data System (ADS)

    Massman, W. J.

    2012-10-01

    Heating any soil during a sufficiently intense wildfire or prescribed burn can alter it irreversibly, causing many significant, long-term biological, chemical, and hydrological effects. Given the climate-change-driven increasing probability of wildfires and the increasing use of prescribed burns by land managers, it is important to better understand the dynamics of the coupled heat and moisture transport in soil during these extreme heating events. Furthermore, improved understanding and modeling of heat and mass transport during extreme conditions should provide insights into the associated transport mechanisms under more normal conditions. The present study describes a numerical model developed to simulate soil heat and moisture transport during fires where the surface heating often ranges between 10,000 and 100,000 W m-2 for several minutes to several hours. Basically, the model extends methods commonly used to model coupled heat flow and moisture evaporation at ambient conditions into regions of extreme dryness and heat. But it also incorporates some infrequently used formulations for temperature dependencies of the soil specific heat, thermal conductivity, and the water retention curve, as well as advective effects due to the large changes in volume that occur when liquid water is rapidly volatilized. Model performance is tested against laboratory measurements of soil temperature and moisture changes at several depths during controlled heating events. Qualitatively, the model agrees with the laboratory observations, namely, it simulates an increase in soil moisture ahead of the drying front (due to the condensation of evaporated soil water at the front) and a hiatus in the soil temperature rise during the strongly evaporative stage of the soil drying. Nevertheless, it is shown that the model is incapable of producing a physically realistic solution because it does not (and, in fact, cannot) represent the relationship between soil water potential and soil

  16. Soil genotoxicity induced by successive applications of chlorothalonil under greenhouse conditions.

    PubMed

    Jin, Xiangxiang; Cui, Ning; Zhou, Wei; Khorram, Mahdi Safaei; Wang, Donghong; Yu, Yunlong

    2014-05-01

    Greenhouse production of vegetables has been developed rapidly in China. High temperature and humidity inside the greenhouse make this environment more suitable for fast reproduction of fungal diseases. Fungicides are among the chemicals used extensively in the greenhouse to prevent crops from invasive infections by phytopathogens; however, little is known about the accumulation of fungicides in soil and their effect on soil quality under greenhouse conditions. In the present study, the accumulation of the fungicide chlorothalonil (CT) and its toxic metabolite hydroxy-chlorothalonil (HCT) in soil as well as their related soil genotoxicity under greenhouse conditions was investigated. The results indicated that both CT and HCT accumulated in soil with repeated applications of CT, and the accumulation level was strongly correlated to application dosage and its frequency. In addition, soil genotoxicity, which was measured by Vicia faba, also increased with the accumulation of CT and HCT, and the main contributor to this phenomenon was CT rather than HCT. The data demonstrated that successive applications of fungicides may result in their accumulation in soil and thus a decline in soil quality.

  17. Soil metabolism of a new herbicide, [14C]Pyribenzoxim, under flooded conditions.

    PubMed

    Chang, Hee-Ra; Koo, Suk-Jin; Kim, Kyun; Ro, Hee-Myong; Moon, Joon-Kwan; Kim, Yong-Hwa; Kim, Jeong-Han

    2007-07-25

    To elucidate the fate of a new pyrimidinyloxybenzoic herbicide, pyribenzoxim, a soil metabolism study was carried out with [14C]pyribenzoxim applied to a sandy loam soil under flooded conditions. The material balance of applied radioactivity ranged from 96.4 to 104.4% and from 96.1 to 101.9% for nonsterile and sterile soils, respectively. The half-life of [14C]pyribenzoxim was calculated to be approximately 1.3 and 9.4 days for nonsterile and sterile soils, respectively. The metabolites identified during the study were 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M1) and 2-hydroxy-6-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M2), resulting from the cleavage of the ester bond and subsequent hydrolysis. The nonextractable radioactivity levels increased to 37.8% for nonsterile conditions at 50 days after treatment and to 38.2% for sterile conditions at 60 days after treatment. Fractionation of the nonextractable soil residues indicated that bound radioactivity was associated mainly with humin fraction. No significant volatile products or [14C]carbon dioxide was observed during the study. On the basis of these results, pyribenzoxim is considered to undergo rapid degradation in soil by microbial and chemical reactions, mainly hydrolysis, which limits its transfer to and accumulation in lower soil layers and groundwater. Therefore, the possibility of environmental contamination from the use of pyribenzoxim is expected to be very low.

  18. Proliferation of diversified clostridial species during biological soil disinfestation incorporated with plant biomass under various conditions.

    PubMed

    Mowlick, Subrata; Takehara, Toshiaki; Kaku, Nobuo; Ueki, Katsuji; Ueki, Atsuko

    2013-09-01

    Biological soil disinfestation (BSD) involves the anaerobic decomposition of plant biomass by microbial communities leading to control of plant pathogens. We analyzed bacterial communities in soil of a model experiment of BSD, as affected by biomass incorporation under various conditions, to find out the major anaerobic bacterial groups which emerged after BSD treatments. The soil was treated with Brassica juncea plants, wheat bran, or Avena strigosa plants, irrigated at 20 or 30 % moisture content and incubated at 25-30 °C for 17 days. The population of Fusarium oxysporum f. sp. spinaciae incorporated at the start of the experiment declined markedly for some BSD conditions and rather high concentrations of acetate and butyrate were detected from these BSD-treated soils. The polymerase chain reaction-denaturing gradient gel electrophoresis analysis based on the V3 region of 16S rRNA gene sequences from the soil DNA revealed that bacterial profiles greatly changed according to the treatment conditions. Based on the clone library analysis, phylogenetically diverse clostridial species appeared exceedingly dominant in the bacterial community of BSD soil incorporated with Brassica plants or wheat bran, in which the pathogen was suppressed completely. Species in the class Clostridia such as Clostridium saccharobutylicum, Clostridium acetobutylicum, Clostridium xylanovorans, Oxobacter pfennigii, Clostridium pasteurianum, Clostridium sufflavum, Clostridium cylindrosporum, etc. were commonly recognized as closely related species of the dominant clone groups from these soil samples.

  19. Bacterial diversity of soil aggregates of different sizes in various land use conditions

    NASA Astrophysics Data System (ADS)

    Ivanova, Ekaterina; Azida, Thakahova; Olga, Kutovaya

    2014-05-01

    The patterns of soil microbiome structure may be a universal and very sensitive indicator of soil quality (soil "health") used for optimization and biologization of agricultural systems. The understanding of how microbial diversity influenses, and is influenced by, the environment can only be attained by analyses at scales relevant to those at which processes influencing microbial diversity actually operate. The basic structural and functional unit of the soil is a soil aggregate, which is actually a microcosm of the associative co-existing groups of microorganisms that form characteristic ecological food chains. It is known that many important microbial processes occur in spatially segregated microenvironments in soil leading to a microscale biogeography. The Metagenomic library of typical chernozem in conditions of different land use systems was created. Total genomic DNA was extracted from 0.5 g of the frozen soil after mechanical destruction. Sample preparation and sequencing was performed on a GS Junior ("Roche»", Switzerland) according to manufacturer's recommendations, using the universal primers to the variable regions V4 gene 16S - rRNA - F515 (GTGCCAGCMGCCGCGGTAA) and R806 (GGACT-ACVSGGGTATCTAAT). It is shown that the system of land use is a stronger determinant of the taxonomic composition of the soil microbial community, rather than the size of the structural units. In soil samples from different land use systems the presence of accessory components was revealed. They may be used as indicators of processes of soil recovery, soil degradation or soil exhaustion processes occuring in the agroecosystems. The comparative analysis of microbial communities of chernozem aggregates investigated demonstrates the statistically valuable differences in the amount of bacterial phyla and Archean domain content as well as the species richness in aggregates of various size fractions. The occurrence of specific components in the taxonomic structure of micro-and macro

  20. Molybdenum isotope fractionation in soils: Influence of redox conditions, organic matter, and atmospheric inputs

    NASA Astrophysics Data System (ADS)

    Siebert, C.; Pett-Ridge, J. C.; Opfergelt, S.; Guicharnaud, R. A.; Halliday, A. N.; Burton, K. W.

    2015-08-01

    Molybdenum isotope fractionation accompanying soil development is studied across three pedogenic gradients encompassing a range of controlling factors. These factors include variable redox conditions, organic matter content, Fe and Mn oxy(hydr)oxide content, mineral composition, degree of weathering, pH, type and amount of atmospheric inputs, age, climate, and underlying rock type. Soil profiles from the island of Maui (Hawaii) along a precipitation gradient ranging from 850 to 5050 mm mean annual precipitation show a decrease in average soil δ98Mo from -0.04 ± 0.11‰ at the driest, most oxic site, which is indistinguishable from the basalt parent material (-0.09 ± 0.08‰), to -0.33 ± 0.10‰ at the wettest, most reducing site. A suite of 6 Icelandic soils display a broad trend with heavier δ98Mo values (up to +1.50 ± 0.09‰) in soil horizons that are more weathered and have higher organic matter content. Selective extractions of Mo from different soil components indicate that the association with organic matter and silicate or Ti-oxide residue dominates retention of Mo in these soils, with adsorption on Fe and Mn oxy(hydr)oxides playing a lesser role. Across all basaltic soils, δ98Mo values are lighter in soils that exhibit the most net Mo loss relative to the parent material, and δ98Mo values are heavier in soils that exhibit net Mo gains. A well-drained regolith profile in the Luquillo Mountains of Puerto Rico developed on quartz diorite shows heavier δ98Mo values than the parent material (up to +0.71 ± 0.10‰ with an integrated profile average of +0.28 ± 0.10‰) in soil and shallower saprolite, despite overall moderate loss of 28% of Mo relative to the bedrock. However, the deeper saprolite is unfractionated from bedrock (-0.01 ± 0.10‰, quartz diorite bedrock) indicating that rock weathering dissolution processes and secondary clay formation do not fractionate Mo isotopes. Our data suggest that the Mo mass balance and isotope composition of

  1. Influence of green waste compost on azimsulfuron dissipation and soil functions under oxic and anoxic conditions.

    PubMed

    García-Jaramillo, M; Cox, L; Hermosín, M C; Cerli, C; Kalbitz, K

    2016-04-15

    Concerns have been raised over the sustainability of intensive rice cultivation, where the use of chemical fertilizers and pesticides has been associated with numerous environmental problems. The objective of this study was to test the effect of the herbicide azimsulfuron on important soil functions as affected by amendment with a byproduct of the olive oil industry. Soil was collected from a Mediterranean rice field. Part of it was amended with alperujo compost (AC). Amended and unamended soils were incubated for 43days in presence or not of azimsulfuron, under anoxic-flooded (AF) and oxic-unflooded (OU) conditions. We monitored the dissipation of the herbicide azimsulfuron, C mineralization, soil microbial biomass (SMB) and dissolved organic carbon (DOC) content and its nature. Under AF conditions, the application of compost produced an increase in the dissipation of the herbicide (up to 12.4%). It was related with the higher DOC content, 4 times higher than under OU conditions. Though increases in carbon turnover (under AF and OU conditions) and reduction of SMBC after herbicide application (only under AF conditions) were observed, the differences were not statistically significant. The application of this organic amendment is presented as an efficient management strategy to increase C turnover in agricultural soils and reduce some of the negative effects derived from the application of azimsulfuron under flooded conditions.

  2. Influence of green waste compost on azimsulfuron dissipation and soil functions under oxic and anoxic conditions.

    PubMed

    García-Jaramillo, M; Cox, L; Hermosín, M C; Cerli, C; Kalbitz, K

    2016-04-15

    Concerns have been raised over the sustainability of intensive rice cultivation, where the use of chemical fertilizers and pesticides has been associated with numerous environmental problems. The objective of this study was to test the effect of the herbicide azimsulfuron on important soil functions as affected by amendment with a byproduct of the olive oil industry. Soil was collected from a Mediterranean rice field. Part of it was amended with alperujo compost (AC). Amended and unamended soils were incubated for 43days in presence or not of azimsulfuron, under anoxic-flooded (AF) and oxic-unflooded (OU) conditions. We monitored the dissipation of the herbicide azimsulfuron, C mineralization, soil microbial biomass (SMB) and dissolved organic carbon (DOC) content and its nature. Under AF conditions, the application of compost produced an increase in the dissipation of the herbicide (up to 12.4%). It was related with the higher DOC content, 4 times higher than under OU conditions. Though increases in carbon turnover (under AF and OU conditions) and reduction of SMBC after herbicide application (only under AF conditions) were observed, the differences were not statistically significant. The application of this organic amendment is presented as an efficient management strategy to increase C turnover in agricultural soils and reduce some of the negative effects derived from the application of azimsulfuron under flooded conditions. PMID:26849340

  3. Modeling Soil Sodicity Problems under Dryland and Irrigated Conditions: Case Studies in Argentina and Colombia

    NASA Astrophysics Data System (ADS)

    Pla-Sentís, Ildefonso

    2014-05-01

    Salt-affected soils, both saline and sodic, my develop both under dryland and irrigated conditions, affecting negatively the physical and chemical soil properties, the crop production and the animal and human health.Among the development processes of salt-affected soils, the processes of sodification have been generally received less attention and is less understood than the development of saline soils. Although in both of them, hydrological processes are involved in their development, in the case of sodic soils we have to consider some additional chemical and physicochemical reactions, making more difficult their modeling and prediction. In this contribution we present two case studies: one related to the development of sodic soils in the lowlands of the Argentina Pampas, under dryland conditions and sub-humid temperate climate, with pastures for cattle production; the other deals with the development of sodic soils in the Colombia Cauca Valley, under irrigated conditions and tropical sub-humid climate, in lands used for sugarcane cropping dedicated to sugar and ethanol production. In both cases the development of sodicity in the surface soil is mainly related to the effects of the composition and level of groundwater, affected in the case of Argentina Pampas by the off-site changes in dryland use and management in the upper zones and by the drainage conditions in the lowlands, and in the case of the Cauca Valley, by the on-site irrigation and drainage management in lands with sugarcane. There is shown how the model SALSODIMAR, developed by the main author, based on the balance of water and soluble componentes of both the irrigation water and groundwater under different water and land management conditions, may be adapted for the diagnosis and prediction of both problems, and for the selection of alternatives for their management and amelioration.

  4. Biodegradation of alpha- and beta-hexachlorocyclohexane in a soil slurry under different redox conditions.

    PubMed Central

    Bachmann, A; Walet, P; Wijnen, P; de Bruin, W; Huntjens, J L; Roelofsen, W; Zehnder, A J

    1988-01-01

    Aerobic conditions proved to be best for the microbiol conversion of alpha-hexachlorocyclohexane (alpha-HCH) in a soil slurry. The dry soil contained 400 mg of alpha-HCH per kg. This xenobiotic compound was mineralized within about 18 days at an initial rate of 23 mg/kg of soil per day by the mixed native microbial population of the soil. The only intermediate that was detected during breakdown was pentachlorocyclohexene, which was detected at very small concentrations. Alpha-HCH was also bioconverted under methanogenic conditions. However, a rather long acclimation period (about 30 days) was necessary before degradation started, at a rate of 13 mg/kg of soil per day. Mass balance calculations showed that about 85% of the initial alpha-HCH that was present was converted to monochlorobenzene, 3,5-dichlorophenol, and a trichlorophenol isomer, possibly 2,4,5-trichlorophenol. Under both denitrifying and sulfate-reducing conditions, no significant bioconversion of alpha-HCH was observed. The beta isomer of HCH was recalcitrant at all of the four redox conditions studied. We propose that the specific spatial chloride arrangement of the beta isomer is responsible for its stability. The results reported here with complex soil slurry systems showed that alpha-HCH is, in contrast to the existing data in the literature, best degraded biologically in the presence of oxygen. PMID:2449868

  5. Lignin decomposition and microbial community in paddy soils: effects of alternating redox conditions

    NASA Astrophysics Data System (ADS)

    Cerli, Chiara; Liu, Qin; Hanke, Alexander; Kaiser, Klaus; Kalbitz, Karsten

    2013-04-01

    Paddy soils are characterised by interchanging cycles of anaerobic and aerobic conditions. Such fluctuations cause continuous changes in soil solution chemistry as well as in the composition and physiological responses of the microbial community. Temporary deficiency in oxygen creates conditions favourable to facultative or obligates anaerobic bacteria, while aerobic communities can thrive in the period of water absence. These alterations can strongly affect soil processes, in particular organic matter (OM) accumulation and mineralization. In submerged soils, lignin generally constitutes a major portion of the total OM because of hampered degradation under anoxic conditions. The alternating redox cycles resulting from paddy soil management might promote both degradation and preservation of lignin, affecting the overall composition and reactivity of total and dissolved OM. We sampled soils subjected to cycles of anoxic (rice growing period) and oxic (harvest and growth of other crops) conditions since 700 and 2000 years. We incubated suspended Ap material, sampled from the two paddy plus two corresponding non-paddy control soils under oxic and anoxic condition, for 3 months, interrupted by a short period of three weeks (from day 21 to day 43) with reversed redox conditions. At each sampling time (day 2, 21, 42, 63, 84), we determined lignin-derived phenols (by CuO oxidation) as well as phospholipids fatty acids contents and composition. We aimed to highlight changes in lignin decomposition as related to the potential rapid changes in microbial community composition. Since the studied paddy soils had a long history of wet rice cultivation, the microbial community should be well adapted to interchanging oxic and anoxic cycles, therefore fully expressing its activity at both conditions. In non-paddy soil changes in redox conditions caused modification of quantity and composition of the microbial community. On the contrary, in well-established paddy soils the microbial

  6. Sensing technologies to measure metabolic activities in soil and assess its health conditions

    NASA Astrophysics Data System (ADS)

    De Cesare, Fabrizio; Macagnano, Antonella

    2013-04-01

    Soil is a complex ecosystem comprised of several and mutually interacting components, both abiotic (organo-mineral associations) and biotic (microbial and pedofaunal populations and plants), where a single parameter depends on other factors and affects the same and other factors, so that a network of influences among organisms coexists with the reciprocal actions between organisms and their environment. Therefore, it is difficult to undoubtedly determine what is the cause and what the effect within relationships between factors and processes. Soil is commonly studied through the evaluation and measurement of single parameters (e.g. the content of soil organic matter (SOM), microbial biomass, enzyme activities, pH, etc.), events (e.g. soil erosion, compaction, etc.) and processes (e.g. soil respiration, carbon fluxes, nitrification/denitrification, etc.), often carried out in laboratory conditions in order to limit the number of factors acting within the ecosystem under study, but missing the information about the global soil environment that way. In the last decade, several scientists have proposed and suggested the need for a holistic approach to soil ecosystems in different contexts. Recently, we have applied a sensing system developed in the last decades and capable of analysing complex mixtures of gases and volatiles (odours or aromas) in atmospheres, namely called electronic nose (EN). Typically, ENs are devices consisting of an array of differentially and partially specific, despite selective, sensors upon diverse coatings of sensitive films, i.e. interacting with single analytes of the same chemical class, despite not highly specific for a single substance, only, but showing also lower extent of cross-selectivity towards compounds of other chemical classes. ENs can be used in the classifications of odours by processing the collected responses of all sensors in the array through pattern recognition analyses, in order to obtain a chemical fingerprint

  7. Rates of Root and Organism Growth, Soil Conditions, and Temporal and Spatial Development of the Rhizosphere

    PubMed Central

    WATT, MICHELLE; SILK, WENDY K.; PASSIOURA, JOHN B.

    2006-01-01

    • Background Roots growing in soil encounter physical, chemical and biological environments that influence their rhizospheres and affect plant growth. Exudates from roots can stimulate or inhibit soil organisms that may release nutrients, infect the root, or modify plant growth via signals. These rhizosphere processes are poorly understood in field conditions. • Scope and Aims We characterize roots and their rhizospheres and rates of growth in units of distance and time so that interactions with soil organisms can be better understood in field conditions. We review: (1) distances between components of the soil, including dead roots remnant from previous plants, and the distances between new roots, their rhizospheres and soil components; (2) characteristic times (distance2/diffusivity) for solutes to travel distances between roots and responsive soil organisms; (3) rates of movement and growth of soil organisms; (4) rates of extension of roots, and how these relate to the rates of anatomical and biochemical ageing of root tissues and the development of the rhizosphere within the soil profile; and (5) numbers of micro-organisms in the rhizosphere and the dependence on the site of attachment to the growing tip. We consider temporal and spatial variation within the rhizosphere to understand the distribution of bacteria and fungi on roots in hard, unploughed soil, and the activities of organisms in the overlapping rhizospheres of living and dead roots clustered in gaps in most field soils. • Conclusions Rhizosphere distances, characteristic times for solute diffusion, and rates of root and organism growth must be considered to understand rhizosphere development. Many values used in our analysis were estimates. The paucity of reliable data underlines the rudimentary state of our knowledge of root–organism interactions in the field. PMID:16551700

  8. No-tillage lessens soil CO2 emissions the most under arid and sandy soil conditions: results from a meta-analysis

    NASA Astrophysics Data System (ADS)

    Abdalla, Khatab; Chivenge, Pauline; Ciais, Philippe; Chaplot, Vincent

    2016-06-01

    The management of agroecosystems plays a crucial role in the global carbon cycle with soil tillage leading to known organic carbon redistributions within soils and changes in soil CO2 emissions. Yet, discrepancies exist on the impact of tillage on soil CO2 emissions and on the main soil and environmental controls. A meta-analysis was conducted using 46 peer-reviewed publications totaling 174 paired observations comparing CO2 emissions over entire seasons or years from tilled and untilled soils across different climates, crop types and soil conditions with the objective of quantifying tillage impact on CO2 emissions and assessing the main controls. On average, tilled soils emitted 21 % more CO2 than untilled soils, which corresponded to a significant difference at P<0.05. The difference increased to 29 % in sandy soils from arid climates with low soil organic carbon content (SOCC < 1 %) and low soil moisture, but tillage had no impact on CO2 fluxes in clayey soils with high background SOCC (> 3 %). Finally, nitrogen fertilization and crop residue management had little effect on the CO2 responses of soils to no-tillage. These results suggest no-tillage is an effective mitigation measure of carbon dioxide losses from dry land soils. They emphasize the importance of including information on soil factors such as texture, aggregate stability and organic carbon content in global models of the carbon cycle.

  9. IT-based soil quality evaluation for agroecologically smart land-use planning in RF conditions

    NASA Astrophysics Data System (ADS)

    Vasenev, Ivan

    2016-04-01

    Activated in the first decades of XXI century global climate, economy and farming changes sharply actualized novel IT-based approaches in soil quality evaluation to address modern agricultural issues with agroecologically smart land-use planning. Despite global projected climate changes will affect a general decline of crop yields (IPCC 2014), RF boreal and subboreal regions will benefit from predicted and already particularly verified temperature warming and increased precipitation (Valentini, Vasenev, 2015) due to essential increasing of growing season length and mild climate conditions favorable for most prospective crops and best available agrotechnologies. However, the essential spatial heterogeneity is mutual feature for most natural and man-changed soils at the Central European region of Russia which is one of the biggest «food baskets» in RF. In these conditions potentially favorable climate circumstances will increase not only soil fertility and workability features but also their dynamics and spatial variability that determine crucial issues of IT-based soil quality evaluation systems development and agroecologically smart farming planning. Developed and verified within the LAMP project (RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) regionally adapted DSS (ACORD-R - RF #2012612944) gives effective informational and methodological support for smart farming agroecological optimization in global climate and farming changes challenges. Information basis for agroecologically smart land-use planning consists of crops and agrotechnologies requirements, regional and local systems of agroecological zoning, local landscape and soil cover patterns, land quality and degradation risk assessments, current and previous farming practices results, agroclimatic predictions and production agroecological models, environmental limitations and planned profitability, fertilizing efficiency DSS ACORD-R. Smart land-use practice refers to sustainable balance

  10. Activity and stability of a complex bacterial soil community under simulated Martian conditions

    NASA Astrophysics Data System (ADS)

    Hansen, Aviaja Anna; Merrison, Jonathan; Nørnberg, Per; Aagaard Lomstein, Bente; Finster, Kai

    2005-04-01

    A simulation experiment with a complex bacterial soil community in a Mars simulation chamber was performed to determine the effect of Martian conditions on community activity, stability and survival. At three different depths in the soil core short-term effects of Martian conditions with and without ultraviolet (UV) exposure corresponding to 8 Martian Sol were compared. Community metabolic activities and functional diversity, measured as glucose respiration and versatility in substrate utilization, respectively, decreased after UV exposure, whereas they remained unaffected by Martian conditions without UV exposure. In contrast, the numbers of culturable bacteria and the genetic diversity were unaffected by the simulated Martian conditions both with and without UV exposure. The genetic diversity of the soil community and of the colonies grown on agar plates were evaluated by denaturant gradient gel electrophoresis (DGGE) on DNA extracts. Desiccation of the soil prior to experimentation affected the functional diversity by decreasing the versatility in substrate utilization. The natural dominance of endospores and Gram-positive bacteria in the investigated Mars-analogue soil may explain the limited effect of the Mars incubations on the survival and community structure. Our results suggest that UV radiation and desiccation are major selecting factors on bacterial functional diversity in terrestrial bacterial communities incubated under simulated Martian conditions. Furthermore, these results suggest that forward contamination of Mars is a matter of great concern in future space missions.

  11. [Optimizing remediation conditions of non-thermal plasma for DDTs heavily contaminated soil].

    PubMed

    Chen, Hai-Hong; Luo, Yong-Ming; Teng, Ying; Liu, Wu-Xing; Pan, Cheng; Li, Zhen-Gao; Huang, Yu-Juan

    2013-01-01

    A series of experiments were carried out in a non-thermal reactor to remove DDTs in heavily contaminated soil by dielectric barrier discharge (DBD). The study aims to investigate the effects of soil properties (including soil particle size and soil water content) and equipment working parameters (e. g. the plasma power, the processing time and discharge atmosphere) on the removal of DDTs from soil. The results showed that DDTs in soil were significantly degraded by the non-thermal plasma produced by dielectric barrier discharge. Removal rate of DDTs increased with increasing processing time. The removal efficiency of DDTs ranged from 95.3% to 99.9% in 20 minutes. The optimum conditions were as follows: 1 kW of the plasma power, 20 minutes of processing time in air discharge atmosphere, 0-0.9 mm soil particle size and 4.5% -10.5% of soil moisture content. The results also showed that o,p'-DDE might be the intermediate dechlorination and dehydrogenation product of the o,p'-DDT after the oxidization.

  12. Generation of High Current Densities by Pure Cultures of Anode-Respiring Geoalkalibacter spp. under Alkaline and Saline Conditions in Microbial Electrochemical Cells

    PubMed Central

    Badalamenti, Jonathan P.; Krajmalnik-Brown, Rosa; Torres, César I.

    2013-01-01

    ABSTRACT Anode-respiring bacteria (ARB) generate electric current in microbial electrochemical cells (MXCs) by channeling electrons from the oxidation of organic substrates to an electrode. Production of high current densities by monocultures in MXCs has resulted almost exclusively from the activity of Geobacter sulfurreducens, a neutrophilic freshwater Fe(III)-reducing bacterium and the highest-current-producing member documented for the Geobacteraceae family of the Deltaproteobacteria. Here we report high current densities generated by haloalkaliphilic Geoalkalibacter spp., thus broadening the capability for high anode respiration rates by including other genera within the Geobacteraceae. In this study, acetate-fed pure cultures of two related Geoalkalibacter spp. produced current densities of 5.0 to 8.3 and 2.4 to 3.3 A m−2 under alkaline (pH 9.3) and saline (1.7% NaCl) conditions, respectively. Chronoamperometric studies of halophilic Glk. subterraneus DSM 23483 and alkaliphilic Glk. ferrihydriticus DSM 17813 suggested that cells performed long-range electron transfer through electrode-attached biofilms and not through soluble electron shuttles. Glk. ferrihydriticus also oxidized ethanol directly to produce current, with maximum current densities of 5.7 to 7.1 A m−2 and coulombic efficiencies of 84 to 95%. Cyclic voltammetry (CV) elicited a sigmoidal response with characteristic onset, midpoint, and saturation potentials, while CV performed in the absence of an electron donor suggested the involvement of redox molecules in the biofilm that were limited by diffusion. These results matched those previously reported for actively respiring Gb. sulfurreducens biofilms producing similar current densities (~5 to 9 A m−2). PMID:23631915

  13. Agricultural machineries wheeling and soil qualities mapping in climatic changes conditions

    NASA Astrophysics Data System (ADS)

    Bergonzoli, S.; Servadio, P.

    2012-04-01

    and on control areas, a software GIS was used. Results shown the highest level of soil compaction caused by the traffic of WTN in term of CI and SS. In fact, increment ratio respect to the control measured after the tractors pass were: CI = 0.65 and 0.14 for WTN and for WTEL respectively; SS = 0.65 and 0.46 for WTN and WTEL respectively. Comparing the two different tires, significant differences were found particularly in the surface layers (0-0.20 m depth): mean values of CI and SS were higher for WTN (0.47 and 1.60 respectively) respect to WTEL. Track area covered by the two treatments respect to the whole field (16.32 ha) were: 0.025 for treatment WTN (0.27 m tires width) having an operative work width of 24 m ; 0.075 for treatment WTEL (0.85 m tires width) having an operative work width of 14 m. Results of this study highlighted that, in these field conditions (clay soil, water content over field capacity), tractor pass with very narrow tires caused a soil compaction level too high up to be impossible to traffic into the field. To operate at these soil water content conditions a tractors fitted with low aspect ratio and low inflation pressure tires is necessary. With lower soil water content, narrow tires allow carrying out fertilization into the inter-row avoiding crop trampling and compacting less percentage of field area respect to the a tractor equipped with large tires. Key words: Tractor, Soil trafficability, Soil compaction, Tires, GPS, GIS. Acknowledgements This work was carried out under the auspices of the special project "Sceneries of adaptation of the Italian agriculture to the climatic changes" (AGROSCENARI) of the Agricultural Research Council, and Italian Ministry of the Agricultural and Forestry Politics.

  14. Crystallization conditions of porphyritic high-K calc-alkaline granitoids in the extreme northeastern Borborema Province, NE Brazil, and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Campos, Benedita Cleide Souza; Vilalva, Frederico Castro Jobim; Nascimento, Marcos Antônio Leite do; Galindo, Antônio Carlos

    2016-10-01

    An integrated textural and chemical study on amphibole, biotite, plagioclase, titanite, epidote, and magnetite was conducted in order to estimate crystallization conditions, along with possible geodynamic implications, for six Ediacaran porphyritic high-K calc-alkaline granite plutons (Monte das Gameleiras, Barcelona, Acari, Caraúbas, Tourão, and Catolé do Rocha) intrusive into Archean to Paleoproterozoic rocks of the São José do Campestre (SJCD) and Rio Piranhas-Seridó (RPSD) domains, northern Borborema Province. The studied rocks include mainly porphyritic leucocratic monzogranites, as well as quartz-monzonites and granodiorites. Textures are marked by K-feldspar megacrysts (5-15 cm long) in a fine-to medium-grained matrix composed of quartz, plagioclase, amphibole, biotite, as well as titanite, epidote, Fesbnd Ti oxides, allanite, apatite, and zircon as accessory minerals. Amphibole, biotite and titanite share similar compositional variations defined by increasing Al and Fe, and decreasing Mg contents from the plutons emplaced into the SJCP (Monte das Gameleiras and Barcelona) towards those in the RPSD (Acari, Caraúbas, Tourão, and Catolé do Rocha). Estimated intensive crystallization parameters reveal a weak westward range of increasing depth of emplacement, pressure and temperature in the study area. The SJCD plutons (to the east) crystallized at shallower crustal depths (14-21 km), under slightly lower pressure (3.8-5.5 kbar) and temperature (701-718 °C) intervals, and high to moderate oxygen fugacity conditions (+0.8 < ΔFQM < +2.0). On the other hand, the RPSD plutons (to the west) were emplaced at slightly deeper depths (18-23 km), under higher, yet variable pressures (4.8-6.2 kbar), temperatures (723-776 °C), and moderate to low oxygen fugacity conditions (-1.0 < ΔFQM < +1.8). These results reinforce the contrasts between the tectono-strutuctural domains of São José do Campestre and Rio Piranhas-Seridó in the northern Borborema Province.

  15. IT-based soil quality evaluation for agroecologically smart land-use planning in RF conditions

    NASA Astrophysics Data System (ADS)

    Vasenev, Ivan

    2016-04-01

    Activated in the first decades of XXI century global climate, economy and farming changes sharply actualized novel IT-based approaches in soil quality evaluation to address modern agricultural issues with agroecologically smart land-use planning. Despite global projected climate changes will affect a general decline of crop yields (IPCC 2014), RF boreal and subboreal regions will benefit from predicted and already particularly verified temperature warming and increased precipitation (Valentini, Vasenev, 2015) due to essential increasing of growing season length and mild climate conditions favorable for most prospective crops and best available agrotechnologies. However, the essential spatial heterogeneity is mutual feature for most natural and man-changed soils at the Central European region of Russia which is one of the biggest «food baskets» in RF. In these conditions potentially favorable climate circumstances will increase not only soil fertility and workability features but also their dynamics and spatial variability that determine crucial issues of IT-based soil quality evaluation systems development and agroecologically smart farming planning. Developed and verified within the LAMP project (RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) regionally adapted DSS (ACORD-R - RF #2012612944) gives effective informational and methodological support for smart farming agroecological optimization in global climate and farming changes challenges. Information basis for agroecologically smart land-use planning consists of crops and agrotechnologies requirements, regional and local systems of agroecological zoning, local landscape and soil cover patterns, land quality and degradation risk assessments, current and previous farming practices results, agroclimatic predictions and production agroecological models, environmental limitations and planned profitability, fertilizing efficiency DSS ACORD-R. Smart land-use practice refers to sustainable balance

  16. How do soil physical conditions for crop growth vary over time under established contrasting tillage regimes?

    NASA Astrophysics Data System (ADS)

    Hallett, Paul; Stobart, Ron; Valentine, Tracy; George, Timothy; Morris, Nathan; Newton, Adrian; McKenzie, Blair

    2014-05-01

    When plant breeders develop modern cereal varieties for the sustainable intensification of agriculture, insufficient thought is given to the impact of tillage on soil physical conditions for crop production. In earlier work, we demonstrated that barley varieties that perform best in ploughed soil (the approach traditionally used for breeding trials) were not the same as those performing best under shallow non-inversion or zero-tillage. We also found that the Quantitative Trait Loci (QTL) associated with improved phosphorus uptake, and hence useful for marker assisted breeding, were not robust between different tillage regimes. The impact of the soil environment had greater impact than the genetics in GxE interactions. It is obvious that soil tillage should be considered when breeding the next generation of crops. Tillage may also have important impacts on carbon storage, but we found that despite greater soil carbon at shallow depths under non-inversion tillage, the carbon stored throughout the soil profile was not affected by tillage. Studies on soil tillage impacts to crop productivity and soil quality are often performed in one season, on single sites that have had insufficient time to develop. Our current research explores multiple sites, on different soils, with temporal measurements of soil physical conditions under contrasting tillage regimes. We use the oldest established contemporary tillage experiments in the United Kingdom, with all sites sharing ploughed and shallow (7cm) non-inversion tillage treatments. In eastern Scotland (Mid Pilmore), the site also has zero tillage and deep ploughing (40 cm) treatments, and was established 11 years ago. In east England there are two sites, both also having a deep non-inversion tillage treatment, and they were established 6 (New Farm Systems) and 8 (STAR) years ago. We measure a range of crop and soil properties at sowing, one month after sowing and post-harvest, including rapid lab based assays that allow high

  17. Effect of heavy metals on soil enzyme activity at different field conditions in Middle Spis mining area (Slovakia).

    PubMed

    Angelovičová, Lenka; Lodenius, Martin; Tulisalo, Esa; Fazekašová, Danica

    2014-12-01

    Heavy metals concentrations were measured in the former mining area located in Hornad river valley (Slovakia). Soil samples were taken in 2012 from 20 sites at two field types (grasslands, heaps of waste material) and two different areas. Total content of heavy metals (Cu, Pb, Zn, Hg), urease (URE), acid phosphatase (ACP), alkaline phosphatase (ALP), soil reaction (pH) were changing depending on the field/area type. The tailing pond and processing plants have been found as the biggest sources of pollution. URE, ACP and ALP activities significantly decreased while the heavy metal contents increased. Significant differences were found among area types in the heavy metal contents and activity of URE. No statistical differences in the content of heavy metals but significant statistical differences for soil pH were found for field types (grassland and heaps). Significant negative correlation was found for URE-Pb, URE-Zn and also between soil reaction and ACP and ALP. PMID:25293393

  18. Effect of heavy metals on soil enzyme activity at different field conditions in Middle Spis mining area (Slovakia).

    PubMed

    Angelovičová, Lenka; Lodenius, Martin; Tulisalo, Esa; Fazekašová, Danica

    2014-12-01

    Heavy metals concentrations were measured in the former mining area located in Hornad river valley (Slovakia). Soil samples were taken in 2012 from 20 sites at two field types (grasslands, heaps of waste material) and two different areas. Total content of heavy metals (Cu, Pb, Zn, Hg), urease (URE), acid phosphatase (ACP), alkaline phosphatase (ALP), soil reaction (pH) were changing depending on the field/area type. The tailing pond and processing plants have been found as the biggest sources of pollution. URE, ACP and ALP activities significantly decreased while the heavy metal contents increased. Significant differences were found among area types in the heavy metal contents and activity of URE. No statistical differences in the content of heavy metals but significant statistical differences for soil pH were found for field types (grassland and heaps). Significant negative correlation was found for URE-Pb, URE-Zn and also between soil reaction and ACP and ALP.

  19. Effects of climatic conditions and soil properties on Cabernet Sauvignon berry growth and anthocyanin profiles.

    PubMed

    Cheng, Guo; He, Yan-Nan; Yue, Tai-Xin; Wang, Jun; Zhang, Zhen-Wen

    2014-01-01

    Climatic conditions and soil type have significant influence on grape ripening and wine quality. The reported study was conducted in two "Cabernet Sauvignon (Vitis vinifera L.V)" vineyards located in Xinjiang, a semiarid wine-producing region of China during two vintages (2011 and 2012). The results indicate that soil and climate affected berry growth and anthocyanin profiles. These two localities were within a distance of 5 km from each other and had soils of different physical and chemical composition. For each vineyard, the differences of anthocyanin concentrations, and parameters concerning berry growth and composition between the two years could be explained by different climatic conditions. Soil effect was studied by investigation of differences in berry composition and anthocyanin profiles between the two vineyards in the same year, which could be explained mainly by the different soil properties, vine water and nitrogen status. Specifically, the soils with less water and organic matter produced looser clusters, heavier berry skins and higher TSS, which contributed to the excellent performance of grapes. Compared with 2011, the increases in anthocyanin concentrations for each vineyard in 2012 could be attributed to smaller number of extreme temperature (>35 °C) days and rainfall, lower vine water status and N level. The explanation for higher anthocyanin concentrations in grape skins from the soils with less water and organic matter could be the vine status differences, lighter berry weight and heavier skin weight at harvest. In particular, grapes from the soils with less water and organic matter had higher levels of 3'5'-substituded, O-methylated and acylated anthocyanins, which represented a positive characteristic conferring more stable pigmentation to the corresponding wine in the future. The present work clarifies the effects of climate and soil on berry growth and anthocyanin profiles, thus providing guidance for production of high-quality wine grapes

  20. Effects of climatic conditions and soil properties on Cabernet Sauvignon berry growth and anthocyanin profiles.

    PubMed

    Cheng, Guo; He, Yan-Nan; Yue, Tai-Xin; Wang, Jun; Zhang, Zhen-Wen

    2014-09-02

    Climatic conditions and soil type have significant influence on grape ripening and wine quality. The reported study was conducted in two "Cabernet Sauvignon (Vitis vinifera L.V)" vineyards located in Xinjiang, a semiarid wine-producing region of China during two vintages (2011 and 2012). The results indicate that soil and climate affected berry growth and anthocyanin profiles. These two localities were within a distance of 5 km from each other and had soils of different physical and chemical composition. For each vineyard, the differences of anthocyanin concentrations, and parameters concerning berry growth and composition between the two years could be explained by different climatic conditions. Soil effect was studied by investigation of differences in berry composition and anthocyanin profiles between the two vineyards in the same year, which could be explained mainly by the different soil properties, vine water and nitrogen status. Specifically, the soils with less water and organic matter produced looser clusters, heavier berry skins and higher TSS, which contributed to the excellent performance of grapes. Compared with 2011, the increases in anthocyanin concentrations for each vineyard in 2012 could be attributed to smaller number of extreme temperature (>35 °C) days and rainfall, lower vine water status and N level. The explanation for higher anthocyanin concentrations in grape skins from the soils with less water and organic matter could be the vine status differences, lighter berry weight and heavier skin weight at harvest. In particular, grapes from the soils with less water and organic matter had higher levels of 3'5'-substituded, O-methylated and acylated anthocyanins, which represented a positive characteristic conferring more stable pigmentation to the corresponding wine in the future. The present work clarifies the effects of climate and soil on berry growth and anthocyanin profiles, thus providing guidance for production of high-quality wine grapes

  1. [Leaching Remediation of Copper and Lead Contaminated Lou Soil by Saponin Under Different Conditions].

    PubMed

    Deng, Hong-xia; Yang, Ya-li; Li, Zhen; Xu, Yan; Li, Rong-hua; Meng, Zhao-fu; Yang, Ya-ti

    2015-04-01

    In order to investigate the leaching remediation effect of the eco-friendly biosurfactant saponin for Cu and Pb in contaminated Lou soil, batch tests method was used to study the leaching effect of saponin solution on single Cu, Pb contaminated Lou soil and mixed Cu and Pb contaminated Lou soil under different conditions such as reaction time, mass concentration of saponin, pH, concentration of background electrolyte and leaching times. The results showed that the maximum leaching removal effect of Cu and Pb in contaminated Lou soil was achieved by complexation of the heavy metals with saponin micelle, when the mass concentration of saponin solution was 50 g x L(-1), pH was 5.0, the reaction time was 240 min, and there was no background electrolyte. In single and mixed contaminated Lou soil, the leaching percentages of Cu were 29.02% and 25.09% after a single leaching with 50 g x L(-1) saponin under optimal condition, while the single leaching percentages of Pb were 31.56% and 28.03%, respectively. The result indicated the removal efficiency of Pb was more significant than that of Cu. After 4 times of leaching, the cumulative leaching percentages of Cu reached 58.92% and 53.11%, while the cumulative leaching percentages of Pb reached 77.69% and 65.32% for single and mixed contaminated Lou soil, respectively. The fractionation results of heavy metals in soil before and after a single leaching showed that the contents of adsorbed and exchangeable Cu and Pb increased in the contaminated soil, while the carbonate-bound, organic bound and sulfide residual Cu and Pb in the contaminated Lou soil could be effectively removed by saponin.

  2. Monitoring soil-water and displacement conditions leading to landslide occurrence in partially saturated clays

    NASA Astrophysics Data System (ADS)

    Bittelli, Marco; Valentino, Roberto; Salvatorelli, Fiorenzo; Rossi Pisa, Paola

    2012-11-01

    Shallow landslides frequently occur during transient rainfall infiltration and under partially saturated conditions. However, a detailed analysis of what triggers them, particularly in clayey soils, is often hindered by the lack of field measurements. It is uncommon, in fact, to capture their occurrence in an instrumented natural slope. This paper presents results from an integrated field experiment monitoring the soil-water and displacement conditions that lead to the occurrence of a shallow landslide in partially saturated clays. The integration of a variety of experimental techniques allowed for the examination of interplay between soil hydrological and mechanical properties. This research also evaluates a slope stability model based on the suction stress concept. Since the model was applied after the occurrence of the landslide, the results are interpreted as a hind-casting technique for model evaluation. Nevertheless, the detailed field measurements acquired during the monitoring activity and the occurrence of a landslide during the experiment provided significant information on model parameters and data interpretation. The station provides remote satellite monitoring of data on weather variables, soil water content and soil suction. A time domain reflectometry cable was installed vertically to detect potential soil failure. The experimental area had a high probability of landslide occurrence. Indeed, slope failure occurred during the observation period, showing the effectiveness of the station in detecting the occurrence, time and depth of landslides. The landslide was triggered in consequence of changes in suction stress. The failure plane occurred at a depth of 1.4 m, corresponding to the interface between a superficial layer of higher permeability of 1 to 1.45 m thickness, slipping over a compacted substrate having lower permeability. The analysis allowed for testing of the validity of the model and the description of the triggering mechanisms of the

  3. Volatilization modeling of two herbicides from soil in a wind tunnel experiment under varying humidity conditions.

    PubMed

    Schneider, Martina; Goss, Kai-Uwe

    2012-11-20

    Volatilization of pesticides from the bare soil surface is drastically reduced when the soil is under dry conditions (i.e., water content lower than the permanent wilting point). This effect is caused by the hydrated mineral surfaces that become available as additional sorption sites under dry conditions. However, established volatilization models do not explicitly consider the hydrated mineral surfaces as an independent sorption compartment and cannot correctly cover the moisture effect on volatilization. Here we integrated the existing mechanistic understanding of sorption of organic compounds to mineral surfaces and its dependence on the hydration status into a simple volatilization model. The resulting model was tested with reported experimental data for two herbicides from a wind tunnel experiment under various well-defined humidity conditions. The required equilibrium sorption coefficients of triallate and trifluralin to the mineral surfaces, K(min/air), at 60% relative humidity were fitted to experimental data and extrapolated to other humidity conditions. The model captures the general trend of the volatilization in different humidity scenarios. The results reveal that it is essential to have high quality input data for K(min/air), the available specific surface area (SSA), the penetration depth of the applied pesticide solution, and the humidity conditions in the soil. The model approach presented here in combination with an improved description of the humidity conditions under dry conditions can be integrated into existing volatilization models that already work well for humid conditions but still lack the mechanistically based description of the volatilization process under dry conditions.

  4. Selenium and sulfur relationships in alfalfa and soil under field conditions, San Joaquin Valley, California

    USGS Publications Warehouse

    Severson, R.C.; Gough, L.P.

    1992-01-01

    Relationships between total Se and S or soluble SeO4 and SO4 in soils and tissue concentrations in alfalfa (Medicago sativa L.), under field conditions in the San Joaquin Valley of California, suggest that the rate of accumulation of Se in alfalfa may be reduced in areas where high Se and S concentrations in soils were measured. These data suggest that the balance between carbonate and sulfate minerals in soil may have a greater influence on uptake of Se by alfalfa than does the balance of SeO4 and SO4 in soil solution. Soil and alfalfa were sampled from areas representing a wide range in soil Se and S concentrations. Specific sampling locations were selected based on a previous study of Se, S, and other elements where 721 soil samples were collected to map landscape variability and distribution of elements. Six multiple-linear regression equations were developed between total and/or soluble soil chemical constituents and tissue concentrations of Se in alfalfa. We chose a regression model that accounted for 72% of the variability in alfalfa Se concentrations based on an association of elements in soil (total C, S, Se, and Sr) determined by factor analysis. To prepare a map showing the spatial distribution of estimated alfalfa Se concentrations, the model was applied to the data from the previously collected 721 soil samples. Estimated alfalfa Se concentrations in most of the study area were within a range that is predicted to produce alfalfa with neither Se deficiency nor toxicity when consumed by livestock. A few small areas are predicted to produce alfalfa that potentially would not meet minimum dietary needs of livestock.

  5. Evaporation from soils subjected to natural boundary conditions at the land-atmospheric interface

    NASA Astrophysics Data System (ADS)

    Smits, K.; Illngasekare, T.; Ngo, V.; Cihan, A.

    2012-04-01

    Bare soil evaporation is a key process for water exchange between the land and the atmosphere and an important component of the water balance in semiarid and arid regions. However, there is no agreement on the best methodology to determine evaporation under different boundary conditions at the land surface. This becomes critical in developing models that couples land to the atmosphere. Because it is difficult to measure evaporation from soil, with the exception of using lysimeters, numerous formulations have been proposed to establish a relationship between the rate of evaporation and soil moisture and/or soil temperature and thermal properties. Different formulations vary in how they partition available energy. A need exists to systematically compare existing methods to experimental data under highly controlled conditions not achievable in the field. The goal of this work is to perform controlled experiments under transient conditions of soil moisture, temperature and wind at the land/atmospheric interface to test different conceptual and mathematical formulations for the soil surface boundary conditions to develop appropriate numerical models to be used in simulations. In this study, to better understand the coupled water-vapor-heat flow processes in the shallow subsurface near the land surface, we modified a previously developed theory by Smits et al. [2011] that allows non-equilibrium liquid/gas phase change with gas phase vapor diffusion to better account for dry soil conditions. The model did not implement fitting parameters such as a vapor enhancement factor that is commonly introduced into the vapor diffusion coefficient as an arbitrary multiplication factor. In order to experimentally test the numerical formulations/code, we performed a two-dimensional physical model experiment under varying boundary conditions using test sand for which the hydraulic and thermal properties were well characterized. Precision data under well-controlled transient heat and

  6. Fate of Pharmaceuticals and Personal Care Products (PPCPs) in Saturated Soil Under Various Redox Conditions

    NASA Astrophysics Data System (ADS)

    Dror, I.; Menahem, A.; Berkowitz, B.

    2014-12-01

    The growing use of PPCPs results in their increasing release to the aquatic environment. Consequently, understanding the fate of PPCPs under environmentally relevant conditions that account for dynamic flow and varying redox states is critical. In this study, the transport of two organometallic PPCPs, Gd-DTPA and Roxarsone (As complex) and their metal salts (Gd(NO3)3, AsNaO2), is investigated. The former is used widely as a contrasting agent for MRI, while the latter is applied extensively as a food additive in the broiler poultry industry. Both of these compounds are excreted from the body, almost unchanged chemically. Gadolinium complexes are not fully eliminated in wastewater treatment and can reach groundwater via irrigation with treated wastewater; Roxarsone can enter groundwater via leaching from manure used as fertilizer. Studies have shown that the transport of PPCPs in groundwater is affected by environmental conditions such as redox states, pH, and soil type. For this study, column experiments using sand or Mediterranean red sandy clay soil were performed under several redox conditions: aerobic, nitrate-reducing, iron-reducing, sulfate-reducing, methanogenic, and very strongly chemical reducing. Batch experiments to determine adsorption isotherms were also performed for the complexes and metal salts. We found that Gd-DTPA transport was affected by the soil type and was not affected by the redox conditions. In contrast, Roxarsone transport was affected mainly by the different redox conditions, showing delayed breakthrough curves as the conditions became more biologically reduced (strong chemical reducing conditions did not affect the transport). We also observed that the metal salts show essentially no transport while the organic complexes display much faster breakthrough. The results suggest that transport of these PPCPs through soil and groundwater is determined by the redox conditions, as well as by soil type and the form of the applied metal (as salt

  7. Alkalization of irrigated soils suitable for orchard growing in steppe Crimea and prospects for their use

    NASA Astrophysics Data System (ADS)

    Klimenko, O. E.

    2016-10-01

    Data of large-scale soil surveys performed by the Ukrgiprosad Institute (Ukrainian Institute for Orchard Growing) in 1997-2013 on irrigated soils of steppe Crimea reserved for orchards on the area of about 3000 ha are discussed. It is shown that all the studied soils are subjected to alkalization with the presence of soda and with an increase in concentrations of sodium and magnesium bicarbonates up to the values toxic for fruit crops. The concentrations and occurrence frequencies of alkaline salts depend on the soil type, the presence of solonetzic features, the amount of carbonates, the particular depth in the soil profile, the subsoiling, and other factors. Within the studied area, some soils are unsuitable or partly suitable for orchard growing. To improve the soil conditions for orchard growing in the areas subjected to alkalization, alkaline salts should be neutralized to nontoxic level, and the soil alkalinity should be reduced using chemical reclamation methods.

  8. Analytical solution describing pesticide volatilization from soil affected by a change in surface condition.

    PubMed

    Yates, S R

    2009-01-01

    An analytical solution describing the fate and transport of pesticides applied to soils has been developed. Two pesticide application methods can be simulated: point-source applications, such as idealized shank or a hot-gas injection method, and a more realistic shank-source application method that includes a vertical pesticide distribution in the soil domain due to a soil fracture caused by a shank. The solutions allow determination of the volatilization rate and other information that could be important for understanding fumigant movement and in the development of regulatory permitting conditions. The solutions can be used to characterize differences in emissions relative to changes in the soil degradation rate, surface barrier conditions, application depth, and soil packing. In some cases, simple algebraic expressions are provided that can be used to obtain the total emissions and total soil degradation. The solutions provide a consistent methodology for determining the total emissions and can be used with other information, such as field and laboratory experimental data, to support the development of fumigant regulations. The uses of the models are illustrated by several examples.

  9. Leaching of oryzalin and diuron through undisturbed vineyard soil columns under outdoor conditions.

    PubMed

    Landry, David; Dousset, Sylvie; Andreux, Francis

    2006-03-01

    Field studies monitoring herbicide pollution in the vineyards of Burgundy (France) have revealed that drinking water reservoirs are contaminated with several pre-emergence herbicides. An assessment of the leaching of two such herbicides, diuron and oryzalin, was therefore performed using lysimeters, under outdoor conditions, from May 2001 to May 2002. Four vineyard soils from Vosne-Romanée (Burgundy) were chosen along a topolithosequence: a rendosol and three calcosols. After 673 mm of rainfall, greater amounts of diuron than oryzalin were measured in percolates: respectively 0.10-0.84% and 0.02-0.43% of applied herbicide, depending on soils. Measurements for diuron metabolites detected greater amounts of DCPMU than DCPU in the percolates: respectively 0.05-0.13% and 0-0.04% of the applied diuron. At the end of the monitoring period, more residues of diuron than oryzalin were recovered in the soil profiles: respectively 4.6-9% and 1.4-4.4%. The oryzalin residues were found mainly in the upper 10 cm of soil columns, whereas diuron residues were present in the whole core. The mobility of both oryzalin and diuron seems fairly well-related to soil organic carbon content; the mobility of diuron is also related to soil texture (sand and coarse material contents). Under such experimental conditions, this study confirms that diuron leaching, and therefore potential groundwater contamination, is greater than that of oryzalin.

  10. Modeling soil evaporation efficiency in a range of soil and atmospheric conditions using a meta-analysis approach

    NASA Astrophysics Data System (ADS)

    Merlin, O.; Stefan, V. G.; Amazirh, A.; Chanzy, A.; Ceschia, E.; Er-Raki, S.; Gentine, P.; Tallec, T.; Ezzahar, J.; Bircher, S.; Beringer, J.; Khabba, S.

    2016-05-01

    A meta-analysis data-driven approach is developed to represent the soil evaporative efficiency (SEE) defined as the ratio of actual to potential soil evaporation. The new model is tested across a bare soil database composed of more than 30 sites around the world, a clay fraction range of 0.02-0.56, a sand fraction range of 0.05-0.92, and about 30,000 acquisition times. SEE is modeled using a soil resistance (rss) formulation based on surface soil moisture (θ) and two resistance parameters rss,ref and θefolding. The data-driven approach aims to express both parameters as a function of observable data including meteorological forcing, cut-off soil moisture value θ1/2 at which SEE=0.5, and first derivative of SEE at θ1/2, named Δθ1/2-1. An analytical relationship between >(rss,ref;θefolding) and >(θ1/2;Δθ1/2-1>) is first built by running a soil energy balance model for two extreme conditions with rss = 0 and rss˜∞ using meteorological forcing solely, and by approaching the middle point from the two (wet and dry) reference points. Two different methods are then investigated to estimate the pair >(θ1/2;Δθ1/2-1>) either from the time series of SEE and θ observations for a given site, or using the soil texture information for all sites. The first method is based on an algorithm specifically designed to accomodate for strongly nonlinear SEE>(θ>) relationships and potentially large random deviations of observed SEE from the mean observed SEE>(θ>). The second method parameterizes θ1/2 as a multi-linear regression of clay and sand percentages, and sets Δθ1/2-1 to a constant mean value for all sites. The new model significantly outperformed the evaporation modules of ISBA (Interaction Sol-Biosphère-Atmosphère), H-TESSEL (Hydrology-Tiled ECMWF Scheme for Surface Exchange over Land), and CLM (Community Land Model). It has potential for integration in various land-surface schemes, and real calibration capabilities using combined thermal and microwave

  11. Prediction of soil and ground water contamination with fungicides of different classes according to soil and climate conditions in Ukrain and other European countries.

    PubMed

    Vavrinevych, O; Antonenko, A; Omelchuk, S; Korshun, M; Bardov, V

    2015-05-01

    It was established that most of tested pesticides are moderately and low persistent in soil and climatic conditions of Ukraine, but more stable in Western and Northern Europe countries due to peculiarities of their climate type and soil characteristics. In addition, it was determined that all studied fungicides pertain to non- and low mobile compound (except moderately mobile pyrimethanil). Recommendations on application of studied fungicides in soil and climatic conditions of Ukraine and other European countries were given. PMID:26042452

  12. Prediction of soil and ground water contamination with fungicides of different classes according to soil and climate conditions in Ukrain and other European countries.

    PubMed

    Vavrinevych, O; Antonenko, A; Omelchuk, S; Korshun, M; Bardov, V

    2015-05-01

    It was established that most of tested pesticides are moderately and low persistent in soil and climatic conditions of Ukraine, but more stable in Western and Northern Europe countries due to peculiarities of their climate type and soil characteristics. In addition, it was determined that all studied fungicides pertain to non- and low mobile compound (except moderately mobile pyrimethanil). Recommendations on application of studied fungicides in soil and climatic conditions of Ukraine and other European countries were given.

  13. Transport of gadolinium- and arsenic-based pharmaceuticals in saturated soil under various redox conditions.

    PubMed

    Menahem, Adi; Dror, Ishai; Berkowitz, Brian

    2016-02-01

    The release of pharmaceuticals and personal care products (PPCPs) to the soil-water environment necessitates understanding of PPCP transport behavior under conditions that account for dynamic flow and varying redox states. This study investigates the transport of two organometallic PPCPs, Gd-DTPA and roxarsone (arsenic compound) and their metal salts (Gd(NO3)3, AsNaO2); Gd-DTPA is used widely as a contrasting agent for MRI, while roxarsone is applied extensively as a food additive in the broiler poultry industry. Here, we present column experiments using sand and Mediterranean red sandy clay soil, performed under several redox conditions. The metal salts were almost completely immobile. In contrast, transport of Gd-DTPA and roxarsone was affected by the soil type. Roxarsone was also affected by the different redox conditions, showing delayed breakthrough curves as the redox potential became more negative due to biological activity (chemically-strong reducing conditions did not affect the transport). Mechanisms that include adsorptive retardation for aerobic and nitrate-reducing conditions, and non-adsorptive retardation for iron-reducing, sulfate-reducing and biologically-strong reducing conditions, are suggested to explain the roxarsone behavior. Gd-DTPA is found to be a stable complex, with potential for high mobility in groundwater systems, whereas roxarsone transport through groundwater systems is affected by redox environments, demonstrating high mobility under aerobic and nitrate-reducing conditions and delayed transport under iron-reducing, sulfate-reducing and biologically-strong reducing conditions.

  14. Microhabitat Effects on N2O Emissions from Floodplain Soils under Controlled Conditions

    NASA Astrophysics Data System (ADS)

    Ley, Martin; Lehmann, Moritz; Niklaus, Pascal; Frey, Beat; Kuhn, Thomas; Luster, Jörg

    2015-04-01

    Semi-terrestrial soils such as floodplain soils are considered to be potential hotspots of nitrous oxide (N2O) emissions. The quantitative assessment of N2O release from these hot spots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging in the environment because of the high spatial and temporal variability. The production and consumption of N2O appears to be linked to the presence or absence of micro-niches, providing specific conditions that may be favorable to either of the microbial pathways that produce or consume N2O. The availability of oxygen, reactive organic carbon, and dissolved nitrogen substrates likely play key roles with regards to the net production of N2O. Previous field studies demonstrated, for example, that flooding can trigger "hot moments" of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. Such microhabitat effects likely depend on soil aggregate formation, plant soil interactions in the rhizosphere and the degradation of organic matter accumulations. In order to assess how these factors can modulate N2O production and consumption under simulated flooding/drying conditions, we have set up a mesocosm experiment with model soils comprising various mixtures of N-rich floodplain soil aggregates (4000 - 250 µm representing large aggregates, or <250 µm representing small aggregates) and inert matrix material (glass beads of 150 - 250 µm size, or quartz sand of 2000 - 3200 µm size, respectively). Soils containing the different aggregate size groups were either planted with willow (Salix viminalis L.), mixed with leaf litter or left untreated. At several time points before, during and after a simulated flood event, we measure the net efflux rate of N2O. In addition, soil water content, redox potential as well as carbon and nitrogen substrate availability are monitored. In order to

  15. Soil texture and climatc conditions for biocrust growth limitation: a meta analysis

    NASA Astrophysics Data System (ADS)

    Fischer, Thomas; Subbotina, Mariia

    2015-04-01

    Along with afforestation, attempts have been made to combat desertification by managing soil crusts, and is has been reported that recovery rates of biocrusts are dependent on many factors, including the type, severity, and extent of disturbance; structure of the vascular plant community; conditions of adjoining substrates; availability of inoculation material; and climate during and after disturbance (Belnap & Eldridge 2001). Because biological soil crusts are known to be more stable on and to prefer fine substrates (Belnap 2001), the question arises as to how successful crust management practices can be applied to coarser soil. In previous studies we observed similar crust biomasses on finer soils under arid and on coarser soils under temperate conditions. We hypothesized that the higher water holding capacity of finer substrates would favor crust development, and that the amount of silt and clay in the substrate that is required for enhanced crust development would vary with changes in climatic conditions. In a global meta study, climatic and soil texture threshold values promoting BSC growth were derived. While examining literature sources, it became evident that the amount of studies to be incorporated into this meta analysis was reversely related to the amount of common environmental parameters they share. We selected annual mean precipitaion, mean temperature and the amount of silt and clay as driving variables for crust growth. Response variable was the "relative crust biomass", which was computed per literature source as the ratio between each individual crust biomass value of the given study to the study maximum value reported. We distinguished lichen, green algal, cyanobacterial and moss crusts. To quantify threshold conditions at which crust biomass responded to differences in texture and climate, we (I) determined correlations between bioclimatic variables, (II) calculated linear models to determine the effect of typical climatic variables with soil

  16. Colloid-Facilitated Transport of Cations in an Unsaturated Fractured Soil Under Transient Conditions

    SciTech Connect

    Ryan, Joseph

    2015-01-31

    Rainfall experiments were conducted using intact soil cores and an instrumented soil pedon to examine the effect of physical heterogeneity and rainfall characteristics on the mobilization of colloids, organic matter, cesium, and strontium in a fractured soil. To measure the spatial variability of infiltration of colloids and contaminants, samples were collected through a 19-port grid placed below the soil core in laboratory study and in 27 samplers at multiple depths in the soil pedon in the field study. Cesium and strontium were applied to the soil cores and the soil pedon prior to mobilization experiments. Rainwater solutions of multiple ionic strengths and organic matter concentrations were applied to the soil cores and soil pedon to mobilize in situ colloids, cesium, and strontium. The mobilization of colloids and metal cations occurred through preferential flow paths in the soil cores. Compared to steady rainfall, greater amounts of colloids were mobilized during rainfall interrupted by pauses, which indicates that the supply of colloids to be mobilized was replenished during the pauses. A maximum in the amount of mobilized colloids were mobilized during a rainfall following a pause of 2.5 d. Pauses of shorter or longer duration resulted in less colloid mobilization. Freeze-thaw cycles, a transient condition in winter, enhanced colloid mobilization and colloid-facilitated transport of cesium and strontium in the soil cores. The exchange of solutes between the soil matrix and macropores caused a hysteretic mobilization of colloids, cesium, and strontium during changes in ionic strength. Colloid-facilitated mobilization of cesium and strontium was important at low ionic strength in fractures where slow flow allowed greater exchange of flow between the fractures and the surrounding matrix. The release of cesium and strontium by cation exchange occurred at high ionic strength in fractures where there is a little exchange of pore water with the surrounding matrix

  17. A non-equilibrium model for soil heating and evaporation under extreme conditions

    NASA Astrophysics Data System (ADS)

    Massman, W. J.

    2014-12-01

    Extreme heating of soils during fires can have long-term and irreversible consequences and given the increasing use of prescribed fire by land managers and the increasing probability of wildfires associated with global warming, one approach to improving understanding of these consequences is to better understand and model the dynamics of the coupled heat, (liquid) moisture, and vapor transport in soils during extreme heating events. The present study describes a model developed to simulate non-equilibrium soil evaporation and the transport of heat, moisture, and water vapor under conditions during fires where the surface heating of the soil often ranges between 10,000 and 100,000 Wm-2 for several minutes to several hours. The Hertz-Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Model performance is tested against laboratory measurements of soil temperature and moisture changes. Testing the present model with different formulations for soil hydraulic conductivity, water retention curve, water activity, and the non-equilibrium evaporative source term, indicates that virtually all the model's successes result from the use of a temperature dependent condensation coefficient in the evaporative source term, a rather surprising and unexpected result. On the other hand, the model solution is not a completely faithful representation of the laboratory data. Nevertheless, this new non-equilibrium model circumvents many of the problems that plagued an equilibrium model developed for the same purpose (Massman 2012: Water Resources Research 48, WR011710) and provides a much more physically realistic simulation than the earlier model. Finally, the present model should provide insight into modeling of heat and mass transport and evaporation, not only during high temperature and low moisture conditions, but for modeling these soil processes under less extreme environmental conditions as well.

  18. A study of X100 pipeline steel passivation in mildly alkaline bicarbonate solutions using electrochemical impedance spectroscopy under potentiodynamic conditions and Mott-Schottky

    NASA Astrophysics Data System (ADS)

    Gadala, Ibrahim M.; Alfantazi, Akram

    2015-12-01

    The key steps involved in X100 pipeline steel passivation in bicarbonate-based simulated soil solutions from the pre-passive to transpassive potential regions have been analyzed here using a step-wise anodizing-electrochemical impedance spectroscopy (EIS) routine. Pre-passive steps involve parallel dissolution-adsorption in early stages followed by clear diffusion-adsorption control shortly before iron hydroxide formation. Aggressive NS4 chlorides/sulfate promote steel dissolution whilst inhibiting diffusion in pre-passive steps. Diffusive and adsorptive effects remain during iron hydroxide formation, but withdraw shortly thereafter during its removal and the development of the stable iron carbonate passive layer. Passive layer protectiveness is evaluated using EIS fitting, current density analysis, and correlations with semiconductive parameters, consistently revealing improved robustness in colder, bicarbonate-rich, chloride/sulfate-free conditions. Ferrous oxide formation at higher potentials results in markedly lower impedances with disordered behavior, and the involvement of the iron(III) valence state is observed in Mott-Schottky tests exclusively for 75 °C conditions.

  19. Land agroecological quality assessment in conditions of high spatial soil cover variability at the Pereslavskoye Opolye.

    NASA Astrophysics Data System (ADS)

    Morev, Dmitriy; Vasenev, Ivan

    2015-04-01

    The essential spatial variability is mutual feature for most natural and man-changed soils at the Central region of European territory of Russia. The original spatial heterogeneity of forest soils has been further complicated by a specific land-use history and human impacts. For demand-driven land-use planning and decision making the quantitative analysis and agroecological interpretation of representative soil cover spatial variability is an important and challenging task that receives increasing attention from private companies, governmental and environmental bodies. Pereslavskoye Opolye is traditionally actively used in agriculture due to dominated high-quality cultivated soddy-podzoluvisols which are relatively reached in organic matter (especially for conditions of the North part at the European territory of Russia). However, the soil cover patterns are often very complicated even within the field that significantly influences on crop yield variability and have to be considered in farming system development and land agroecological quality evaluation. The detailed investigations of soil regimes and mapping of the winter rye yield have been carried in conditions of two representative fields with slopes sharply contrasted both in aspects and degrees. Rye biological productivity and weed infestation have been measured in elementary plots of 0.25 m2 with the following analysis the quality of the yield. In the same plot soil temperature and moisture have been measured by portable devices. Soil sampling was provided from three upper layers by drilling. The results of ray yield detailed mapping shown high differences both in average values and within-field variability on different slopes. In case of low-gradient slope (field 1) there is variability of ray yield from 39.4 to 44.8 dt/ha. In case of expressed slope (field 2) the same species of winter rye grown with the same technology has essentially lower yield and within-field variability from 20 to 29.6 dt/ha. The

  20. Chromium Release from a COPR-Contaminated Soil at Varying Water Content and Redox Conditions.

    PubMed

    Matern, Katrin; Mansfeldt, Tim

    2016-07-01

    Many soils in the region of Kanpur, North India, are heavily affected by the leather industry and its upstream supplier sector, as indicated by elevated chromium (Cr) contents. Under reducing conditions-for instance, at water saturation after monsoon rain or flood irrigation-the dynamic and species distribution of Cr may be affected due to changes in redox potential (E). In this study, the influence of E on the speciation and release of Cr from a contaminated agricultural soil was investigated. A soil sample that was affected by hyperalkaline leachate from chromite ore processing residue, was taken and packed in soil columns, and subjected to a saturation-drainage-saturation cycle. After initial water saturation, the E dropped slowly to minimum values of around ‒100 mV (calculated to pH 7), while E was controlled by CrO/CrO(s), or CrO/(Fe,Cr)OOH redox couples. Soil drainage resulted in a quick return to oxidizing conditions; i.e., E > 300 mV. The Cr species distribution and release showed a clear trend with E. At the beginning of the experiment, under oxidizing and weakly reducing conditions (E range from >100 to 300 mV), Cr(VI) was released in particular. However, under moderately reducing conditions (E range from 100 to -100 mV), Cr was gradually immobilized and irreversible sequestered via reductive precipitation. The results presented in this study provide an improved understanding of the mobility of Cr(VI) in contaminated soils at varying water contents, which is essential for the evaluation of environmental risks in this region. PMID:27380074

  1. Evaluation-of soil enzyme activities as soil quality indicators in sludge-amended soils.

    PubMed

    Dindar, Efsun; Şağban, Fatma Olcay Topaç; Başkaya, Hüseyin Savaş

    2015-07-01

    Soil enzymatic activities are commonly used as biomarkers of soil quality. Several organic and inorganic compounds found in municipal wastewater sludges can possibly be used as fertilizers. Monitoring and evaluating the quality of sludge amended soils with enzyme activities accepted as a beneficial practice with respect to sustainable soil management. In the present study, variation of some enzyme activities (Alkaline phosphatase, dehydrogenase, urease and beta-glucosidase activities) in soils amended with municipal wastewater sludge at different application rates (50, 100 and 200 t ha(-1) dry sludge) was evaluated. Air dried sludge samples were applied to soil pots and sludge-soil mixtures were incubated during a period of three months at 28 degrees C. The results of the study showed that municipal wastewater sludge amendment apparently increased urease, dehydrogenase, alkaline phosphatase and P-glucosidase activities in soil by 48-70%, 14-47%, 33-66% and 9-14%, respectively. The maximum activity was generally observed in sludge amended soil with dose of 200 t ha(-1). Urease activity appeared to be a better indicator of soil enhancement with wastewater sludge, as its activity was more strongly increased by sludge amendment. Accordingly, urease activity is suggested to be soil quality indicator best suited for measuring existing conditions and potential changes in sludge-amended soil.

  2. Assessing the evolution of soil moisture and vegetation conditions during the 2012 United States flash drought

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study examines the evolution of several model-based and satellite-derived drought metrics sensitive to soil moisture and vegetation conditions during the extreme flash drought event that impacted major agricultural areas across the central U.S. during 2012. Standardized anomalies from the remo...

  3. NATIONAL RESULTS FROM THE 2011 NATIONAL WETLAND CONDITION ASSESSMENT (NWCA) SOILS ANALYSIS

    EPA Science Inventory

    In 2011, US Environmental Protection Agency conducted the first National Wetland Condition Assessment (NWCA). Field crews conducted one-day surveys of over 1000 wetlands across the contiguous United States. For every wetland sampled, soils were collected by layer (i.e., horizon)...

  4. Bacillus spp. from rainforest soil promote plant growth under limited nitrogen conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The aim of this study was to evaluate effects of PGPR (Plant Growth Promoting Rhizobacteria) isolated from rainforest on different plants under limited nitrogen conditions. Methods and Results: Bacterial isolates from a Peruvian rainforest soil were screened for plant growth promoting effects...

  5. Exploring transport dynamics of "new" and "old" tracers under varying hydrologic conditions in structured soils

    NASA Astrophysics Data System (ADS)

    Bishop, Joshua; Callaghan, Michael; Mikulic, Danijela; Cey, Edwin

    2016-04-01

    Fine-grained, structured soils are prone to preferential flow along macropores that can enhance vertical migration of surface applied contaminants ("new" solutes) due to water bypassing the soil matrix. This same bypass phenomenon can also inhibit the flushing of in situ salt or other contaminants ("old" solutes), thereby hampering reclamation of previously impacted soils. In all cases, mass exchange between the soil matrix and macropores is a significant control on water and solute movement in the soil profile. The dynamics of these mass exchange processes and the associated transport of both new and old tracers were studied in field- and core-scale experiments on low permeability, macroporous soils. A multi-year investigation of new (DFBA) and old (Cl) tracer transport was completed on two 20 x 20 m test plots within a tile-drained field. Irrigation water was applied to one test plot, while the second plot served as an unirrigated control. Detailed monitoring, including wells, lysimeters, tensiometers, soil cores, tile drains, and electrical resistivity tomography, revealed a comprehensive picture of the hydraulic system response and distribution of chemical tracers over multiple field seasons. A large difference in solute transport within and between seasons was attributed to temporally varying hydrologic (water table and soil moisture) conditions, despite similar total volumes of water application. Time-varying soil hydraulic properties and soil macropore saturation were believed to play a major role, and were explored in more detail with large, intact soil monolith experiments. Two paired-core infiltration experiments were completed using the same volumes of irrigation water, but different irrigation rates and durations. The migration of new (Br, I, and dye) and old (Cl) tracers was monitored throughout the experiments, and the final tracer distribution was characterized by destructive sampling at the conclusion of irrigation. The spatial and temporal

  6. Alkaline-resistance model of subtilisin ALP I, a novel alkaline subtilisin.

    PubMed

    Maeda, H; Mizutani, O; Yamagata, Y; Ichishima, E; Nakajima, T

    2001-05-01

    The alkaline-resistance mechanism of the alkaline-stable enzymes is not yet known. To clarify the mechanism of alkaline-resistance of alkaline subtilisin, structural changes of two typical subtilisins, subtilisin ALP I (ALP I) and subtilisin Sendai (Sendai), were studied by means of physicochemical methods. Subtilisin NAT (NAT), which exhibits no alkaline resistance, was examined as a control. ALP I gradually lost its activity, accompanied by protein degradation, but, on the contrary, Sendai was stable under alkaline conditions. CD spectral measurements at neutral and alkaline pH indicated no apparent differences between ALP I and Sendai. A significant difference was observed on measurement of fluorescence emission spectra of the tryptophan residues of ALP I that were exposed on the enzyme surface. The fluorescence intensity of ALP I was greatly reduced under alkaline conditions; moreover, the reduction was reversed when alkaline-treated ALP I was neutralized. The fluorescence spectrum of Sendai remained unchanged. The enzymatic and optical activities of NAT were lost at high pH, indicating a lack of functional and structural stability in an alkaline environment. Judging from these results, the alkaline resistance is closely related to the surface structure of the enzyme molecule.

  7. Electrokinetic remediation of a Cu-Zn contaminated red soil by controlling the voltage and conditioning catholyte pH.

    PubMed

    Zhou, Dong-Mei; Deng, Chang-Fen; Cang, Long; Alshawabkeh, Akram N

    2005-10-01

    Electrokinetics is an innovative technique for treating heavy metals contaminated soil, especially low pH soils such as the Chinese red soil (Udic Ferrisols). In this paper, a Cu-Zn contaminated red soil is treated by electrokinetics. When the Cu-Zn contaminated red soil was treated without control of catholyte pH during the electrokinetic treatment, the soil pH in the soil sections near cathode after the experiment was high above 6, which resulted in accumulation of large amounts of Cu and Zn in the soil sections with such high pH values. Compared to soil Cu, soil Zn was more efficiently removed from the soil by a controlled electrokinetic method. Application of lactic acid as catholyte pH conditioning solution caused an efficient removal of Cu and Zn from the soil. Increasing the electrolyte strength (salt concentration) of the conditioning solution further increased Cu removal, but did not cause a significant improvement for soil Zn. Soil Cu and Zn fractions after the electrokinetic treatments were analyzed using sequential extraction method, which indicated that Cu and Zn precipitation in the soil section closest to the cathode in the treatments without catholyte pH control limited their removal from the soil column. When the catholyte pH was controlled by lactic acid and CaCl(2), the soil Cu and Zn removal percentage after 554 h running reached 63% and 65%, respectively. Moreover, both the residual soil Cu and Zn concentrations were lower than 100 mg kg(-1), which is adequate and meets the requirement of the Chinese soil environmental quality standards. PMID:16202805

  8. Global Evaporation Estimates from SMAP Passive Microwave Soil Moisture Retrievals Using Conditional Sampling.

    NASA Astrophysics Data System (ADS)

    Vreugdenhil, M.; Entekhabi, D.; Konings, A. G.; Salvucci, G.; Hogan, P.

    2015-12-01

    Evaporation links the water, energy and carbon cycles over land yet even its climatology on global scale is not observed. Tower-based flux measurements are sparse and do not cover diverse biomes and climates. In the last decades, many strategies to derive evaporation based on remote sensing measurements have been developed. However, these methods are dependent on a variety of assumptions and auxiliary data, making them more prone to error propagation. A more data-driven method was developed by Salvucci (2001), who found that under statistical stationary conditions the expected change in soil moisture storage is zero when conditioned to a certain storage for a certain time interval. Consequently, using the water balance, precipitation conditionally averaged to the soil moisture storage is equal to the total loss: evaporation and drainage. Using only soil moisture and precipitation data as model inputs reduces the sources of uncertainty. In this presentation we provide the first estimates of global evaporation from NASA's Soil Moisture Active Passive mission by applying the conditional sampling method to passive microwave soil moisture time series and in situ precipitation data. The obtained evaporation estimates show a good correspondence to measured evaporation from eddy correlation towers over selected field sites. Subsequently, a simple approach is developed to directly estimate evaporation from SMAP soil moisture data. This approach enables the investigation of dynamics in evaporation during the dry-down after storms. The timing of the transition between the different stages of evaporation is assessed for different climates especially the transition from stage 1 to stage 2 evaporation; atmosphere limited evaporation to soil limited evaporation respectively. Investigations into the dynamics of unstressed evaporation and transpiration and the transition from stage 1 to stage 2 evaporation increases our understanding of water stress and soil desiccation. It also

  9. Dissipation kinetics of tetraconazole in three types of soil and water under laboratory condition.

    PubMed

    Alam, Samsul; Sengupta, Dwaipayan; Kole, Ramen Kumar; Bhattacharyya, Anjan

    2013-12-01

    Laboratory experiment was conducted to understand the persistence behavior of tetraconazole in three soils of West Bengal (alluvial, red lateritic, and coastal saline) and also in water maintained at three different pH (4.0, 7.0, and 9.2) conditions. Processed soil samples (100 g) were spiked at two treatment doses: 2.5 μg/g (T₁) and 5.0 μg/g (T₂). Double distilled buffered water (200 ml) was spiked at two treatment doses: 1.0 μg/ml (T₁) and 2.00 μg/ml (T₂). The tetraconazole dissipation followed first-order reaction kinetics and the residual half-life (T₁/₂) values in soil were found to be in the range of 66.9-77.2 days for T₁ and 73.4-86.0 days for T₂. The persistence increased in the order red lateritic > new alluvial > coastal saline. Interestingly, the red lateritic soil exhibited the lowest pH (5.56) and organic carbon (0.52%) content as compared to other two soils. However, the dissipation of tetraconazole in case of water was not pH dependant. The T₁/₂ values in water were in the range of 94 to 125 days. The study indicated the persistent nature of tetraconazole in soil and water.

  10. Observing soil water dynamics under two field conditions by a novel sensor system

    NASA Astrophysics Data System (ADS)

    Sheng, W.; Sun, Y.; Schulze Lammers, P.; Schumann, H.; Berg, A.; Shi, C.; Wang, C.

    2011-10-01

    SummarySufficiently available soil water is a basic requirement in agricultural production. Monitoring soil water dynamics (SWD) in the root zone is an optimal approach for managing a crop's growth. This study presents a novel sensor system that simultaneously measures volumetric soil water content (VSWC), apparent electrical conductivity (EC a) and soil temperature at two different soil depths (shallow: 16 cm; deep: 36 cm). For testing its feasibility in the field, two prototypes were installed, one in bare soil and the other in a sugar beet ( Beta vulgaris L.) field in the summer of 2010. Following a sequence of rainfall events randomly distributed over the experimental period, we observed distinct responses from the sensors at each monitored depth in both field conditions. In addition to the multi-parameter measurements, the novel sensor design includes a series of technical advantages such as solar-powered operation, wireless communication, and being relatively easy to install/remove. Thus, the developed wireless sensor system is promising for networked applications in precision farming.

  11. Antimony retention and release from drained and waterlogged shooting range soil under field conditions.

    PubMed

    Hockmann, Kerstin; Tandy, Susan; Lenz, Markus; Reiser, René; Conesa, Héctor M; Keller, Martin; Studer, Björn; Schulin, Rainer

    2015-09-01

    Many soils polluted by antimony (Sb) are subject to fluctuating waterlogging conditions; yet, little is known about how these affect the mobility of this toxic element under field conditions. Here, we compared Sb leaching from a calcareous shooting range soil under drained and waterlogged conditions using four large outdoor lysimeters. After monitoring the leachate samples taken at bi-weekly intervals for >1.5 years under drained conditions, two of the lysimeters were subjected to waterlogging with a water table fluctuating according to natural rainfall water infiltration. Antimony leachate concentrations under drained conditions showed a strong seasonal fluctuation between 110 μg L(-1) in summer and <40 μg L(-1) in winter, which closely correlated with fluctuations in dissolved organic carbon (DOC) concentrations. With the development of anaerobic conditions upon waterlogging, Sb in leachate decreased to 2-5 μg L(-1) Sb and remained stable at this level. Antimony speciation measurements in soil solution indicated that this decrease in Sb(V) concentrations was attributable to the reduction of Sb(V) to Sb(III) and the stronger sorption affinity of the latter to iron (Fe) (hydr)oxide phases. Our results demonstrate the importance of considering seasonal and waterlogging effects in the assessment of the risks from Sb-contaminated sites.

  12. Microbial inoculants and organic amendment improves plant establishment and soil rehabilitation under semiarid conditions.

    PubMed

    Mengual, Carmen; Schoebitz, Mauricio; Azcón, Rosario; Roldán, Antonio

    2014-02-15

    The re-establishment of autochthonous shrub species is an essential strategy for recovering degraded soils under semiarid Mediterranean conditions. A field assay was carried out to determine the combined effects of the inoculation with native rhizobacteria (Bacillus megaterium, Enterobacter sp, Bacillus thuringiensis and Bacillus sp) and the addition of composted sugar beet (SB) residue on physicochemical soil properties and Lavandula dentata L. establishment. One year after planting, Bacillus sp. and B. megaterium + SB were the most effective treatments for increasing shoot dry biomass (by 5-fold with respect to control) and Enterobacter sp + SB was the most effective treatments for increasing dry root biomass. All the treatments evaluated significantly increased the foliar nutrient content (NPK) compared to control values (except B. thuringiensis + SB). The organic amendment had significantly increased available phosphorus content in rhizosphere soil by 29% respect to the control. Enterobacter sp combined with sugar beet residue improved total N content in soil (by 46% respect to the control) as well as microbiological and biochemical properties. The selection of the most efficient rhizobacteria strains and their combined effect with organic residue seems to be a critical point that drives the effectiveness of using these biotechnological tools for the revegetation and rehabilitation of degraded soils under semiarid conditions. PMID:24463051

  13. Yield performance of cowpea plant introductions grown in calcareous soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cowpea or Southernpea [Vigna unguiculata (L.) Walp.] is an important legume crop used as a feed for livestock, as a green vegetable and for consumption of its dry beans which provide 22-25% protein. The crop is very sensitive to alkaline soil conditions. When grown at a soil pH of 7.5 or higher, co...

  14. Cadmium and zinc interactions and their transfer in soil-crop system under actual field conditions.

    PubMed

    Nan, Zhongren; Li, Jijun; Zhang, Jianming; Cheng, Guodong

    2002-02-21

    The transfer of Cd and Zn from calcareous soils nearby a non-ferrous mining and smelting bases to the spring wheat (Triticum aestivum L.) and corn (Zea mays L.) tissues and the interactions between the two metals concerned were investigated under actual field conditions. Samples of soils and entire crops were randomly collected during harvest time in 1998 in the Baiyin region. The soil metal contents showed that the furrows had been polluted (mean values: 3.16 mg kg(-1) for Cd; 146.78 mg kg(-1) for Zn) and the significant spatial variation of the soil contamination existed here (ranges, Cd: 0.14-19.3 mg kg(-1); Zn: 43.5-565.0 mg kg(-1)). The translocation ratios of the two metals from soil to crop parts in the region studied were relatively lower and the order of the element transfer in different plant tissues was root > stem > grain. The transfer ratio of element Cd was lower than that of element Zn. Cd and Zn uptake by the crop structures could be best described by four models (P < 0.01): linear; exponential; quadratic; and cubic. Apart from a linear relationship between the element Cd in the corn grains and soils, models were generally non-lincar. An analysis of Cd-Zn interaction mechanism led to the conclusion that the effects of the two metals were synergistic to each other under field conditions, in which increasing Cd and Zn contents in soils could increase the accumulations of Zn or Cd in the two crops.

  15. Mosses influence phosphorus cycling in rich fens by driving redox conditions in shallow soils.

    PubMed

    Crowley, Katherine F; Bedford, Barbara L

    2011-09-01

    Mosses play an integral role in the hydrologic regimes of ecosystems where they cover the soil surface, and thus affect biogeochemical cycling of elements influenced by soil oxidation-reduction (redox) reactions, including the plant growth-limiting nutrients, nitrogen and phosphorus (P). In rich fens where P often limits plant growth, we hypothesized that feedbacks between mosses and redox conditions would determine P availability to shallow-rooted forb species that constitute much of these wetlands' unusually high plant species diversity. In a moss removal experiment in three fens, forb tissue P and microbial P were greater while anion exchange membrane (AEM) resin P was lower where mosses occurred than where they were removed, suggesting both higher availability and greater demand for P in moss-covered soils. Coupled physicochemical and biological mechanisms drove moss effects on P cycling, ultimately through effects on soil oxygenation or reduction: higher redox potential underlying mosses corresponded to greater microbial activity, phosphatase enzyme activity, and colonization by arbuscular mycorrhizal fungi (AMF), all of which can promote greater P availability to plants. These more oxidized soils stimulated: (1) greater microbial activity and root vigor; (2) correspondingly greater P demand via microbial uptake, forb uptake, and iron (Fe)-P reactions; and (3) greater P supply through soil and root phosphatase activity and AMF colonization. This work demonstrates that mosses improve vascular plant P acquisition by alleviating stresses caused by reducing conditions that would otherwise prevail in shallow underlying soils, thus providing a mechanism by which mosses facilitate plant species diversity in rich fens.

  16. ALP (Alkaline Phosphatase) Test

    MedlinePlus

    ... known as: ALK PHOS; Alkp Formal name: Alkaline Phosphatase Related tests: AST ; ALT ; GGT ; Bilirubin ; Liver Panel ; Bone Markers ; Alkaline Phosphatase Isoenzymes; Bone Specific ALP All content on Lab ...

  17. Temporal and spatial development of surface soil conditions at two created riverine marshes.

    PubMed

    Anderson, Christopher J; Mitsch, William J; Nairn, Robert W

    2005-01-01

    The amount of time it takes for created wetlands to develop soils comparable to natural wetlands is relatively unknown. Surface soil changes over time were evaluated in two created wetlands (approximately 1 ha each) at the Olentangy River Wetland Research Park in Columbus, Ohio. The two wetlands were constructed in 1993 to be identical in size and geomorphology, and maintained to have the same hydrology. The only initial difference between the wetlands was that one was planted with native macrophytes while the other was not. In May 2004, soil samples were collected (10 yr and 2 mo after the wetlands were flooded) and compared to samples collected in 1993 (after the wetlands were excavated but before flooding) and 1995 (18 mo after the wetlands were flooded). In all three years, soils were split into surface (0-8 cm) and subsurface (8-16 cm) depths and analyzed for soil organic matter, total C, total P, available P, exchangeable cations, and pH. Soils in the two wetlands have changed substantially through sedimentation and organic accretion. Between 1993 and 1995, soils were most influenced by the deposition of senescent macroalgae, the mobilization of soluble nutrients, and the precipitation of CaCO(3). Between 1995 and 2004, soil parameters were influenced more by the deposition of organic matter from colonized macrophyte communities. Mean percent organic matter at the surface increased from 5.3 +/- 0.1% in 1993, 6.1 +/- 0.2% in 1995, to 9.5 +/- 0.2% in 2004. Mean total P increased from 493 +/- 18 microg g(-1) in 1993, 600 +/- 23 microg g(-1) in 1995, to 724 +/- 20 microg g(-1) in 2004. Spatial analyses of percent organic matter (a commonly used indicator of hydric soil condition) at both wetlands in 1993, 1995, and 2004 showed that soil conditions have become increasingly more variable. High spatial structure (autocorrelation) between data points was detected in 1993 and 2004, with data in 2004 exhibiting a much higher overall variance and narrower range of

  18. Temporal and spatial development of surface soil conditions at two created riverine marshes.

    PubMed

    Anderson, Christopher J; Mitsch, William J; Nairn, Robert W

    2005-01-01

    The amount of time it takes for created wetlands to develop soils comparable to natural wetlands is relatively unknown. Surface soil changes over time were evaluated in two created wetlands (approximately 1 ha each) at the Olentangy River Wetland Research Park in Columbus, Ohio. The two wetlands were constructed in 1993 to be identical in size and geomorphology, and maintained to have the same hydrology. The only initial difference between the wetlands was that one was planted with native macrophytes while the other was not. In May 2004, soil samples were collected (10 yr and 2 mo after the wetlands were flooded) and compared to samples collected in 1993 (after the wetlands were excavated but before flooding) and 1995 (18 mo after the wetlands were flooded). In all three years, soils were split into surface (0-8 cm) and subsurface (8-16 cm) depths and analyzed for soil organic matter, total C, total P, available P, exchangeable cations, and pH. Soils in the two wetlands have changed substantially through sedimentation and organic accretion. Between 1993 and 1995, soils were most influenced by the deposition of senescent macroalgae, the mobilization of soluble nutrients, and the precipitation of CaCO(3). Between 1995 and 2004, soil parameters were influenced more by the deposition of organic matter from colonized macrophyte communities. Mean percent organic matter at the surface increased from 5.3 +/- 0.1% in 1993, 6.1 +/- 0.2% in 1995, to 9.5 +/- 0.2% in 2004. Mean total P increased from 493 +/- 18 microg g(-1) in 1993, 600 +/- 23 microg g(-1) in 1995, to 724 +/- 20 microg g(-1) in 2004. Spatial analyses of percent organic matter (a commonly used indicator of hydric soil condition) at both wetlands in 1993, 1995, and 2004 showed that soil conditions have become increasingly more variable. High spatial structure (autocorrelation) between data points was detected in 1993 and 2004, with data in 2004 exhibiting a much higher overall variance and narrower range of

  19. Compartmental modeling of PAH transport in soil column experiments under variably-saturated flow conditions

    NASA Astrophysics Data System (ADS)

    Sartori, F.; Sericano, J. L.; Wade, T. L.; Mohanty, B. P.

    2012-12-01

    Knowledge about the mobilization of polycyclic aromatic hydrocarbons (PAH) from PAH-laden soils or sediments is important to understand their bioavailability, and ultimately assess the environmental risk of PAH transport from surface soils into the groundwater. The transport and kinetics of three PAH from a spiked soil layer (2-3 cm soil depth), Phenanthrene-d10 (1900 ng/g), Naphthalene-d8 (1500 ng/g), and Pyrene-d10 (1800 ng/g), were investigated by performing a series of 8 rainfall events during 25 days in two large, replicate soil columns (length: 35 cm; diameter: 14.5 cm; 1 Pore Volume [PV]=2.29 L) under variably-saturated flow conditions. The water-methanol displacing solutions were at volumetric fractions of 0.3 and 0.6 during day 1 (E1) through E8 and E12-E22, respectively. Soil matric potential (h) was monitored at 5-cm and 20-cm depth and volumetric water content (θ) at 12.5-cm and 27.5-cm depth. Soil solution was sampled at 5 cm- (n=46) and 27.5-cm depth (n=46), and the effluent at the bottom of the column (n=163). HYDRUS-1D was used for inverse modeling of h and θ data and to predict θ at specific times and soil depth increments. First-order kinetics, compartmental models describing the transfer of PAH from the soil compartment to the soil solution compartment (desorption) and vice versa (sorption), were used to estimate mass transfer rates (φs, sorption; φd, desorption; φe, elimination), PAH mass in each compartment, and partition coefficients (Kd). Phenanthrene breakthrough curve could be interpreted through a two-parameter, two-compartment model corresponding to the common two-site sorption model, whose parameter estimates (and 95% confidence intervals) were φd=2.72 (2.31, 3.19) PV-1 and φe=4.67 (3.82, 5.7 ) PV-1. Naphthalene breakthrough curve followed a simple one-compartment elimination model, φe=2.0 (1.9, 2.1) PV-1, and that of Pyrene a three-parameter, two-compartment model, φs=0.0454 (0.00853, 0.0603) PV-1, φd=0.165 (0.0319, 0.855) PV

  20. Partitioning of Evapotranspiration Into Soil Evaporation and Plant Transpiration Using Isotopes of Water in Controlled Conditions

    NASA Astrophysics Data System (ADS)

    Rothfuss, Y.; Bariac, T.; Braud, I.; Biron, P.; Richard, P.; Canale, L.; Durand, J.; Gaudet, J.

    2007-12-01

    Rainfall recycling by evapotranspiration from continental surfaces is certainly the most unknown component of the global water cycle. This is due to the large variability of rainfall as well as the heterogeneity of these continental surfaces, both in time and space. Traditional measuring methods such as sap flow, micro lysimeter, water and energy balance estimation (Bowen ratio, eddy correlation) have been used since the 70s for a monitoring of real evapotranspiration fluxes over crops and others plant covers. A complementary method consists in using isotopic biogeochemistry. When making specific hypothesis, it is possible to identify and quantify the different sources of the atmospheric water vapour (vegetation and soil at different scales). Analysis of the heavy stable isotopic ratios of water in both liquid and vapour phases: 18O and 2H can allow determining the history of the water in the soil since the last rainfall event (infiltration, re-evaporation) or the root extraction depths. Field campaigns measurements (plants and soils), interpreted using the Keeling Plot method allowed some progress in the partition between evaporation and transpiration understanding. But the experimental design is not sufficient to mechanistically describe the water processes involved. The study of all the interactions is difficult due to the large number of controlling variables describing climate, vegetation and soil characteristics. A monolith experiment (including soil and growing plant) was carried out in a reactor called RUBIC (Reactor Used for Continental Isotopic Biogeochemistry, Bariac et al., Geochim. Cosmochim. Acta., 1991). Controlled conditions allowed a monitoring and regulation of climatic parameters (net radiation, air temperature, vapour pressure deficit, CO2 partial pressure, and wind speed). It was also necessary to fix soil (structure, texture, and water content) and vegetation (specie and seeding density) parameters. The collected data allow us to improve our

  1. A Lagrangian model for soil water dynamics during rainfall-driven conditions

    NASA Astrophysics Data System (ADS)

    Zehe, Erwin; Jackisch, Conrad

    2016-09-01

    Within this study we propose a stochastic approach to simulate soil water dynamics in the unsaturated zone by using a non-linear, space domain random walk of water particles. Soil water is represented by particles of constant mass, which travel according to the Itô form of the Fokker-Planck equation. The model concept builds on established soil physics by estimating the drift velocity and the diffusion term based on the soil water characteristics. A naive random walk, which assumes all water particles to move at the same drift velocity and diffusivity, overestimated depletion of soil moisture gradients compared to a Richards solver. This is because soil water and hence the corresponding water particles in smaller pore size fractions are, due to the non-linear decrease in soil hydraulic conductivity with decreasing soil moisture, much less mobile. After accounting for this subscale variability in particle mobility, the particle model and a Richards solver performed highly similarly during simulated wetting and drying circles in three distinctly different soils. Both models were in very good accordance during rainfall-driven conditions, regardless of the intensity and type of the rainfall forcing and the shape of the initial state. Within subsequent drying cycles the particle model was typically slightly slower in depleting soil moisture gradients than the Richards model. Within a real-world benchmark, the particle model and the Richards solver showed the same deficiencies in matching observed reactions of topsoil moisture to a natural rainfall event. The particle model performance, however, clearly improved after a straightforward implementation of rapid non-equilibrium infiltration, which treats event water as different types of particles, which travel initially in the largest pore fraction at maximum velocity and experience a slow diffusive mixing with the pre-event water particles. The proposed Lagrangian approach is hence a promising, easy

  2. Measurements of heat fluxes and soil moisture patterns in the field conditions

    NASA Astrophysics Data System (ADS)

    Sanda, M.; Snehota, M.; Haase, T.; Wild, J.

    2011-12-01

    New combined thermal and soil moisture unit coded TMS2 is presented. It is a prototype designed on good experience with TMS1. The device combines three thermometers for use approximately at -10, 0 and +15 cm relative to soil surface when installed vertically. Soil moisture measurement is performed based on time domain transmission (TDT) principle for the full range of soil moisture. Presented new version incorporates lifetime power supply for approximately 5 year operation and life time permanent data storage (0.5 mil logs) if values are acquired every 10 minutes. Lifetime operation log accompanies lifetime data storage with lockable data blocks. Data are retrieved by contact portable pocket collector. Both vertical/surface or buriable/subsurface installation is possible thanks to additional communication interface on demand. Original model TMS1, proved durability in harsh outdoor environment with good functioning in wet conditions withstanding mechanical destruction. Extended testing in the sandstone area of the National Park Bohemian Switzerland, Czech Republic is performed since 2009 by the Institute of Botany of the ASCR. Results of long-term measurement at hundreds of localities are successfully used for i) evaluation of species-specific environmental requirements (for different species of plants, bryophytes and fungi) and ii) extrapolation of microclimatic conditions over large areas of rugged sandstone relief with assistance of accurate, LiDAR based, digital terrain model. TMS1 units are also applied for continuous measurement of temperature and moisture of coarse woody debris, which serves as an important substrate for establishment and growth of seedlings and is thus crucial for natural regeneration of many forest ecosystems. The TMS1 sensors have been tested and calibrated in soil laboratories of Czech Technical University in Prague for three soil materials: arenic cambisol, podzol and quartz sand, showing good linearity and minor influence of the

  3. Integrating legacy soil information in a Digital Soil Mapping approach based on a modified conditioned Latin Hypercube Sampling design

    NASA Astrophysics Data System (ADS)

    Stumpf, Felix; Schmidt, Karsten; Behrens, Thorsten; Schoenbrodt-Stitt, Sarah; Scholten, Thomas

    2014-05-01

    One crucial component of a Digital Soil Mapping (DSM) framework is outlined by geo-referenced soil observations. Nevertheless, highly informative legacy soil information, acquired by traditional soil surveys, is often neglected due to lacking accordance with specific statistical DSM designs. The focus of this study is to integrate legacy data into a state-of-the-art DSM approach, based on a modified conditioned Latin Hypercube Sampling (cLHS) design and Random Forest. Furthermore, by means of the cLHS modification the scope of actually unique cLHS sampling locations is widened in order to compensate limited accessability in the field. As well, the maximally stratified cLHS design is not diluted by the modification. Exemplarily the target variables of the modelling are represented by sand and clay fractions. The study site is a small mountainous hydrological catchment of 4.2 km² in the reservoir of the Three Gorges Dam in Central China. The modification is accomplished by demarcating the histogram borders of each cLHS stratum, which are based on the multivariate cLHS feature space. Thereby, all potential sample locations per stratum are identified. This provides a possibility to integrate legacy data samples that match one of the newly created sample locations, and flexibility with respect to field accessibility. Consequently, six legacy data samples, taken from a total sample size of n = 30 were integrated into the sampling design and for all strata several potential sample locations are identified. The comparability of the modified and standard cLHS data sets is approved by (i) identifying their feature space coverage with respect to the cLHS stratifying variables, and (ii) by assessing the Random Forest accuracy estimates.

  4. Testing of Icy-Soil Sample Delivery in Simulated Martian Conditions (Animation)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for animation

    This movie clip shows testing under simulated Mars conditions on Earth in preparation for NASA's Phoenix Mars Lander using its robotic arm for delivering a sample to the doors of a laboratory oven.

    The icy soil used in the testing flowed easily from the scoop during all tests at Martian temperatures. On Mars, icy soil has stuck to the scoop, a surprise that may be related to composition of the soil at the landing site.

    This testing was done at Honeybee Robotics Spacecraft Mechanisms Corp., New York, which supplied the Phoenix scoop.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASAaE(TM)s Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  5. Microhabitat Effects on N2O Emissions from Floodplain Soils under Controlled Conditions

    NASA Astrophysics Data System (ADS)

    Ley, Martin; Lehmann, Moritz F.; Niklaus, Pascal A.; Kuhn, Thomas; Luster, Jörg

    2016-04-01

    Semi-terrestrial soils such as floodplain soils are considered to be potential hotspots of nitrous oxide (N2O) emissions. The quantitative assessment of N2O release from these hotspots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging because of their high spatial and temporal variability. The production and consumption of N2O appears to be linked to the presence or absence of micro-niches, providing specific conditions that may be favorable to either of the relevant microbial pathways. Flood events have been shown to trigger moments of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. This coupling might be modulated by microhabitat effects related to soil aggregate formation, root soil interactions and the degradation of organic matter accumulations. In order to assess how these factors can modulate N2O production and consumption under simulated flooding/drying conditions, we have set up a mesocosm experiment with N-rich floodplain soils comprising different combinations of soil aggregate size classes and inert matrix material. These model soils were either planted with basket willow (Salix viminalis L.), mixed with leaf litter, or left untreated. Throughout a simulated flood event, we repeatedly measured the net N2O production rate. In addition, soil water content, redox potential, as well as C and N substrate availability were monitored. In order to gain insight into the sources of, and biogeochemical controls on N2O production, we also measured the bulk δ15N signature of the produced N2O, as well as its intramolecular 15N site preference (SP). In this presentation we focus on a period of enhanced N2O emission during the drying phase after 48 hrs of flooding. We will discuss the observed emission patterns in the context of possible treatment effects. Soils with large aggregates showed a

  6. Interactions with soils conditioned by different vegetation: a potential explanation of bromus tectorum L. invasion into salt-deserts?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion by Bromus tectorum L. may condition the soil and increase nutrient availability. We hypothesized that nutrient poor soils of the arid Honey Lake Valley of northeastern California U.S.A., similar in physical and chemical properties, but conditioned by either B. tectorum, Krascheninniko...

  7. Root responses to soil physical conditions; growth dynamics from field to cell.

    PubMed

    Bengough, A Glyn; Bransby, M Fraser; Hans, Joachim; McKenna, Stephen J; Roberts, Tim J; Valentine, Tracy A

    2006-01-01

    Root growth in the field is often slowed by a combination of soil physical stresses, including mechanical impedance, water stress, and oxygen deficiency. The stresses operating may vary continually, depending on the location of the root in the soil profile, the prevailing soil water conditions, and the degree to which the soil has been compacted. The dynamics of root growth responses are considered in this paper, together with the cellular responses that underlie them. Certain root responses facilitate elongation in hard soil, for example, increased sloughing of border cells and exudation from the root cap decreases friction; and thickening of the root relieves stress in front of the root apex and decreases buckling. Whole root systems may also grow preferentially in loose versus dense soil, but this response depends on genotype and the spatial arrangement of loose and compact soil with respect to the main root axes. Decreased root elongation is often accompanied by a decrease in both cell flux and axial cell extension, and recent computer-based models are increasing our understanding of these processes. In the case of mechanical impedance, large changes in cell shape occur, giving rise to shorter fatter cells. There is still uncertainty about many aspects of this response, including the changes in cell walls that control axial versus radial extension, and the degree to which the epidermis, cortex, and stele control root elongation. Optical flow techniques enable tracking of root surfaces with time to yield estimates of two-dimensional velocity fields. It is demonstrated that these techniques can be applied successfully to time-lapse sequences of confocal microscope images of living roots, in order to determine velocity fields and strain rates of groups of cells. In combination with new molecular approaches this provides a promising way of investigating and modelling the mechanisms controlling growth perturbations in response to environmental stresses.

  8. Atrazine degradation by fungal co-culture enzyme extracts under different soil conditions.

    PubMed

    Chan-Cupul, Wilberth; Heredia-Abarca, Gabriela; Rodríguez-Vázquez, Refugio

    2016-01-01

    This investigation was undertaken to determine the atrazine degradation by fungal enzyme extracts (FEEs) in a clay-loam soil microcosm contaminated at field application rate (5 μg g(-1)) and to study the influence of different soil microcosm conditions, including the effect of soil sterilization, water holding capacity, soil pH and type of FEEs used in atrazine degradation through a 2(4) factorial experimental design. The Trametes maxima-Paecilomyces carneus co-culture extract contained more laccase activity and hydrogen peroxide (H2O2) content (laccase = 18956.0 U mg protein(-1), H2O2 = 6.2 mg L(-1)) than the T. maxima monoculture extract (laccase = 12866.7 U mg protein(-1), H2O2 = 4.0 mg L(-1)). Both extracts were able to degrade atrazine at 100%; however, the T. maxima monoculture extract (0.32 h) achieved a lower half-degradation time than its co-culture with P. carneus (1.2 h). The FEE type (p = 0.03) and soil pH (p = 0.01) significantly affected atrazine degradation. The best degradation rate was achieved by the T. maxima monoculture extract in an acid soil (pH = 4.86). This study demonstrated that both the monoculture extracts of the native strain T. maxima and its co-culture with P. carneus can efficiently and quickly degrade atrazine in clay-loam soils.

  9. Chloride and organic chlorine in forest soils: storage, residence times, and influence of ecological conditions.

    PubMed

    Redon, Paul-Olivier; Abdelouas, Abdesselam; Bastviken, David; Cecchini, Sébastien; Nicolas, Manuel; Thiry, Yves

    2011-09-01

    Recent studies have shown that extensive chlorination of natural organic matter significantly affects chlorine (Cl) residence time in soils. This natural biogeochemical process must be considered when developing the conceptual models used as the basis for safety assessments regarding the potential health impacts of 36-chlorine released from present and planned radioactive waste disposal facilities. In this study, we surveyed 51 French forested areas to determine the variability in chlorine speciation and storage in soils. Concentrations of total chlorine (Cl(tot)) and organic chlorine (Cl(org)) were determined in litterfall, forest floor and mineral soil samples. Cl(org) constituted 11-100% of Cl(tot), with the highest concentrations being found in the humus layer (34-689 mg Cl(org) kg(-1)). In terms of areal storage (53 - 400 kg Cl(org) ha(-1)) the mineral soil dominated due to its greater thickness (40 cm). Cl(org) concentrations and estimated retention of organochlorine in the humus layer were correlated with Cl input, total Cl concentration, organic carbon content, soil pH and the dominant tree species. Cl(org) concentration in mineral soil was not significantly influenced by the studied environmental factors, however increasing Cl:C ratios with depth could indicate selective preservation of chlorinated organic molecules. Litterfall contributions of Cl were significant but generally minor compared to other fluxes and stocks. Assuming steady-state conditions, known annual wet deposition and measured inventories in soil, the theoretical average residence time calculated for total chlorine (inorganic (Cl(in)) and organic) was 5-fold higher than that estimated for Cl(in) alone. Consideration of the Cl(org) pool is therefore clearly important in studies of overall Cl cycling in terrestrial ecosystems. PMID:21761932

  10. Benefits and limitations of pig slurry to reclaim bare mine soils under Mediterranean semiarid conditions

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Faz, Ángel; Acosta, Jose A.; Kabas, Sebla; Martínez-Martínez, Silvia; Ángeles Muñoz, M.

    2013-04-01

    In this study, the effects of pig slurry application on reclamation of mine soils from Cartagena-La Unión Mining District (SE Spain) were investigated in a field experiment. Exchangeable metals (Cd, Cu, Pb and Zn), total organic carbon, total nitrogen, soluble carbon, microbial biomass and three enzyme activities were periodically monitored during 67 days. In addition, one year after the application of the pig slurry, soil and developed vegetation was sampled. Results showed that only exchangeable Cd and Zn significantly decreased in the amended plots, mainly for Cd, with decreases of 98%. The rest of metals and chemical properties did not change with time after application of amendments, showing values not significantly different than those present before pig slurry application. Soluble carbon, microbial biomass carbon and the enzyme activities increased after the application of pig slurry. However, after various days these parameters started a decreasing trend until reaching values similar to the control from approximately day 25. Thus, mainly precipitation as phosphate from the waste was very effective for Cd immobilization. No increments were observed in soil organic carbon because the organic carbon applied with the slurry was too low to be significantly detected. Nonetheless, pig slurry is a good fertilizer owing to the high quantity of nutrients provided, needed to promote the development of vegetation. One year after application, a native vegetation cover (25-30%) was reached by spontaneous colonization. Triggered plant growth by the effect of amendment improved soil conditions, particularly by the help of the medium created by their rhizosphere systems. Increments in soil organic carbon and total nitrogen, and decreases in the exchangeable metals fraction concentration were observed in rhizospheric soils when compared to the bare soils. This improvement in soil quality mediated by vegetation was more efficient than the direct effect of the amendment. In

  11. Testing of the hydromechanical prediction model of soil erosion under the conditions of Georgia

    NASA Astrophysics Data System (ADS)

    Gogichaishvili, G. P.; Kirvalidze, D. R.; Gorjomeladze, O. L.

    2014-09-01

    A hydromechanical model for predicting water (rain-induced) soil erosion was tested on the experimental plots of the Research Institute of Tea and Subtropical Crops in Zendidi village (the Ajara Autonomous Republic) and the Sabashvili Institute of Soil Science, Agrochemistry, and Melioration in Khevi and Kitskhi villages (Upper Imeretia, Western Georgia). A comparison of factual and predicted values of rain-induced erosion for the plots with permanent black fallow showed that the model overestimated the average annual soil loss for the yellow-brown strongly eroded soil in Zendidi village by 23.22 t/ha (133%). This value ranged in different years from 18 to 1052%. For the plots with corn, the predicted value of annual erosion was by 16.94 t/ha higher than the factual value (overestimation of 488%). A comparison of factual and predicted values of rainfall erosion for the plots under sprinkling irrigation also showed that the predicted soil loss was higher than the factual one by 4.14-30.40 t/ha for corn, 6.76-11.14 t/ha for winter wheat, and 15.75-24.12 t/ha for the plots with stubble of winter wheat and barley. Thus, the hydromechanical model for predicting water erosion inadequately describes it under the conditions of Western Georgia and has to be refined.

  12. Biotite weathering in podzolic soil under conditions of a model field experiment

    NASA Astrophysics Data System (ADS)

    Sokolova, T. A.; Tolpeshta, I. I.; Topunova, I. V.

    2010-10-01

    The biotite changes in the 1-5 μm fraction after its occurrence in the F, H, AE, and E horizons of a pale-podzolic soil for five years under conditions of a model field experiment were assessed by X-ray diffraction analysis. It was found that the main changes of the biotite in all the horizons included the degradational transformation of its crystal lattice to interstratified mica-vermiculite structures and vermiculite. The intensity of this process gradually decreased from the F horizon down the profile in parallel with the decrease in the amount of roots and the abundance and activity of microbiota. Chloritized structures were present among the products of the biotite weathering in the H, AE, and E horizons; the degree of chloritization gradually increased from the H horizon to the E horizon. The main identified products of the biotite weathering in the AE and E horizons formed during the 5 years of the model experiment were identified in the clay and fine-silt fractions from these horizons of the native pale-podzolic soils. Therefore, the vermiculite, soil chlorite, and mixed-layer illite-vermiculite minerals in the soils studied could be considered as products of the recent soil functioning. The obtained results and literature data showed that the weathering of biotite resulted in the formation of K- and Al-buffer systems.

  13. Methanogenic archaea are globally ubiquitous in aerated soils and become active under wet anoxic conditions

    PubMed Central

    Angel, Roey; Claus, Peter; Conrad, Ralf

    2012-01-01

    The prototypical representatives of the Euryarchaeota—the methanogens—are oxygen sensitive and are thought to occur only in highly reduced, anoxic environments. However, we found methanogens of the genera Methanosarcina and Methanocella to be present in many types of upland soils (including dryland soils) sampled globally. These methanogens could be readily activated by incubating the soils as slurry under anoxic conditions, as seen by rapid methane production within a few weeks, without any additional carbon source. Analysis of the archaeal 16S ribosomal RNA gene community profile in the incubated samples through terminal restriction fragment length polymorphism and quantification through quantitative PCR indicated dominance of Methanosarcina, whose gene copy numbers also correlated with methane production rates. Analysis of the δ13C of the methane further supported this, as the dominant methanogenic pathway was in most cases aceticlastic, which Methanocella cannot perform. Sequences of the key methanogenic enzyme methyl coenzyme M reductase retrieved from the soil samples before incubation confirmed that Methanosarcina and Methanocella are the dominant methanogens, though some sequences of Methanobrevibacter and Methanobacterium were also detected. The global occurrence of only two active methanogenic archaea supports the hypothesis that these are autochthonous members of the upland soil biome and are well adapted to their environment. PMID:22071343

  14. Transport of gadolinium- and arsenic-based pharmaceuticals in saturated soil under various redox conditions.

    PubMed

    Menahem, Adi; Dror, Ishai; Berkowitz, Brian

    2016-02-01

    The release of pharmaceuticals and personal care products (PPCPs) to the soil-water environment necessitates understanding of PPCP transport behavior under conditions that account for dynamic flow and varying redox states. This study investigates the transport of two organometallic PPCPs, Gd-DTPA and roxarsone (arsenic compound) and their metal salts (Gd(NO3)3, AsNaO2); Gd-DTPA is used widely as a contrasting agent for MRI, while roxarsone is applied extensively as a food additive in the broiler poultry industry. Here, we present column experiments using sand and Mediterranean red sandy clay soil, performed under several redox conditions. The metal salts were almost completely immobile. In contrast, transport of Gd-DTPA and roxarsone was affected by the soil type. Roxarsone was also affected by the different redox conditions, showing delayed breakthrough curves as the redox potential became more negative due to biological activity (chemically-strong reducing conditions did not affect the transport). Mechanisms that include adsorptive retardation for aerobic and nitrate-reducing conditions, and non-adsorptive retardation for iron-reducing, sulfate-reducing and biologically-strong reducing conditions, are suggested to explain the roxarsone behavior. Gd-DTPA is found to be a stable complex, with potential for high mobility in groundwater systems, whereas roxarsone transport through groundwater systems is affected by redox environments, demonstrating high mobility under aerobic and nitrate-reducing conditions and delayed transport under iron-reducing, sulfate-reducing and biologically-strong reducing conditions. PMID:26408978

  15. [Light response of Wisteria sinensis leaves physiological parameters under different soil moisture conditions].

    PubMed

    Xia, Jiang-bao; Zhang, Guang-can; Liu, Gang; Han, Wei; Chen, Jian; Liu, Xia

    2007-01-01

    With two years old Wisteria sinensis as test material, this paper measured the light response of its leaves net photosynthetic rate (Pn), transpiration rate (Tr) and water use efficiency (WUE) under different soil moisture conditions, aimed to ascertain the optimal soil moisture and light conditions of W. sinensis growth. The results showed that the Pn, Tr and WUE had evident threshold responses to the variations of soil moisture and light intensity. To maintain the normal growth and higher levels P. and WUE of W. sinensis, soil volumetric moisture content (Wr) and relative moisture content (Wv) should be within the range of 15.3%-26.5% and 46.4%-80.3%, and the optimal Wv and Wr were 23.3% and 70.6%, respectively. W. sineasis leaves had stronger adaptability to light conditions. When the photosynthetic active radiation (PAR) was 600-1600 micromol x m(-2) x s(-1), the Pn and WUE were at higher level, and the light saturation points of Pn and WUE were all at about 800-1000 x micromol x m(-2) x s(-1). The appearance of non-stomatal limit was significantly correlated with soil moisture and light intensity. When W, ranged from 18.4% to 26.5%, the decline of Pn was mainly caused by stomatal limit rather than PAR. Out of this range, Pn was obviously affected by PAR, and the critical turning point of PAR was observed with the change from stomatal limit to non-stomatal limit. The minimal values of Wv and Wr for the normal growth of W. sinensis were 11.9% and 36.1%, respectively, and the maximal PAR was 1000 micromol x m(-2) x s(-1), the critical point of detriment in leaf photosynthetic organ.

  16. Screening variability and change of soil moisture under wide-ranging climate conditions: Snow dynamics effects.

    PubMed

    Verrot, Lucile; Destouni, Georgia

    2015-01-01

    Soil moisture influences and is influenced by water, climate, and ecosystem conditions, affecting associated ecosystem services in the landscape. This paper couples snow storage-melting dynamics with an analytical modeling approach to screening basin-scale, long-term soil moisture variability and change in a changing climate. This coupling enables assessment of both spatial differences and temporal changes across a wide range of hydro-climatic conditions. Model application is exemplified for two major Swedish hydrological basins, Norrström and Piteälven. These are located along a steep temperature gradient and have experienced different hydro-climatic changes over the time period of study, 1950-2009. Spatially, average intra-annual variability of soil moisture differs considerably between the basins due to their temperature-related differences in snow dynamics. With regard to temporal change, the long-term average state and intra-annual variability of soil moisture have not changed much, while inter-annual variability has changed considerably in response to hydro-climatic changes experienced so far in each basin.

  17. Impact of soil moisture initial conditions on multi model summer predictions over mid-latitudes

    NASA Astrophysics Data System (ADS)

    Ardilouze, Constantin; Prodhomme, Chloé; Batté, Lauriane; Déqué, Michel

    2016-04-01

    Land surface initial conditions have been recognized as a potential source of predictability at seasonal time scales. As an example, results from GLACE-2 (phase 2 of the Global Land-Atmosphere Coupling Experiment) highlighted the impact of spring soil moisture in summer near-surface air temperature prediction over Europe and Northern America with global long-range forecast systems (Koster et al., 2011, van den Hurk et al.,2012). Yet, few studies have explored such an influence over a sufficient hindcast period to produce a robust quantitative assessment. In the framework of the FP7-SPECS project, dedicated experiments have been carried out with June-August hindcasts from 5 distinct Atmosphere Ocean Global Climate Models initialized either by realistic or climatological soil moisture conditions on May 1st. Realistic initialization leads to an improved 2-meter temperature prediction skill over parts of Europe in the multi model, particularly the Balkans peninsula which had been identified as a hot spot of soil moisture-atmosphere coupling (Seneviratne et al. 2006) However no improvement was found over North-American Great Plains in spite of the high potential of this region. Further analyses suggest that this lack of skill stems from a common shortcoming of the models. All of them tend to overestimate the positive feedback between soil moisture, temperature and precipitation with respect to the observations. Hence, tackling model systematic biases over the US Southern Great Plains appears as a necessary prerequisite for summer predictability enhancement.

  18. Biodegradation of select organic pollutants in soil columns under denitrifying conditions

    SciTech Connect

    Ramanand, K.; Balba, M.T.; Duffy, J.

    1995-12-31

    The majority of the biotreatability studies has been confined to laboratory flask assay level. However, these studies may not provide sufficient information for extrapolation to full-scale bioremediation. In this study, laboratory soil columns were used to closely simulate in-situ field conditions and predict the fate of certain aromatic compounds under denitrifying conditions. The soil columns, after sufficient acclimation period, metabolized toluene rapidly with concomitant nitrate consumption. Approximately 6.48 moles of nitrate was utilized per mole of toluene metabolized. This stoichiometry suggested that about 90% of the substrate was mineralized. Increasing the toluene loading rate from 23.4 to 93.5 mg/kg soil/day had no detrimental influence on the microbial degradative capabilities. When sufficient time was allowed for acclimation, the soil microbiota was able to cross-adapt to degrade other aromatic substrates including ethylbenzene, 2-, and 3-fluorobenzoic acid, and 2-, and 3- chlorophenol but was ineffective for degrading o-xylene, 2,3-dichlorophenol (DCP), 3,4-DCP and 3,5-DCP. These findings help explain the fate of these organic contaminants in anoxic environments. 17 refs., 7 figs., 1 tab.

  19. Formation of diphenylthioarsinic acid from diphenylarsinic acid under anaerobic sulfate-reducing soil conditions.

    PubMed

    Hisatomi, Shihoko; Guan, Ling; Nakajima, Mami; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2013-11-15

    Diphenylarsinic acid (DPAA) is a toxic phenylarsenical compound often found around sites contaminated with phenylarsenic chemical warfare agents, diphenylcyanoarsine or diphenylchloroarsine, which were buried in soil after the World Wars. This research concerns the elucidation of the chemical structure of an arsenic metabolite transformed from DPAA under anaerobic sulfate-reducing soil conditions. In LC/ICP-MS analysis, the retention time of the metabolite was identical to that of a major phenylarsenical compound synthesized by chemical reaction of DPAA and hydrogen sulfide. Moreover the mass spectra for the two compounds measured using LC/TOF-MS were similar. Subsequent high resolution mass spectral analysis indicated that two major ions at m/z 261 and 279, observed on both mass spectra, were attributable to C12H10AsS and C12H12AsSO, respectively. These findings strongly suggest that the latter ion is the molecular-related ion ([M+H](+)) of diphenylthioarsinic acid (DPTA; (C6H5)2AsS(OH)) and the former ion is its dehydrated fragment. Thus, our results reveal that DPAA can be transformed to DPTA, as a major metabolite, under sulfate-reducing soil conditions. Moreover, formation of diphenyldithioarsinic acid and subsequent dimerization were predicted by the chemical reaction analysis of DPAA with hydrogen sulfide. This is the first report to elucidate the occurrence of DPAA-thionation in an anaerobic soil. PMID:24007995

  20. Role of chemical composition in the enhanced catalytic activity of Pt-based alloyed ultrathin nanowires for the hydrogen oxidation reaction under alkaline conditions

    DOE PAGES

    Megan E. Scofield; Wong, Stanislaus S.; Zhou, Yuchen; Yue, Shiyu; Wang, Lei; Su, Dong; Tong, Xiao; Vukmirovic, Miomir B.; Adzic, Radoslav R.

    2016-05-19

    With the increased interest in the development of hydrogen fuel cells as a plausible alternative to internal combustion engines, recent work has focused on creating alkaline fuel cells (AFC), which employ an alkaline environment. Working in alkaline as opposed to acidic media yields a number of tangible benefits, including (i) the ability to use cheaper and plentiful precious-metal-free catalysts, due to their increased stability, (ii) a reduction in the amount of degradation and corrosion of Pt-based catalysts, and (iii) a longer operational lifetime for the overall fuel cell configuration. However, in the absence of Pt, no catalyst has achieved activitiesmore » similar to those of Pt. Herein, we have synthesized a number of crystalline ultrathin PtM alloy nanowires (NWs) (M = Fe, Co, Ru, Cu, Au) in order to replace a portion of the costly Pt metal without compromising on activity while simultaneously adding in metals known to exhibit favorable synergistic ligand and strain effects with respect to the host lattice. In fact, our experiments confirm theoretical insights about a clear and correlative dependence between measured activity and chemical composition. We have conclusively demonstrated that our as-synthesized alloy NW catalysts yield improved hydrogen oxidation reaction (HOR) activities as compared with a commercial Pt standard as well as with our as-synthesized Pt NWs. The Pt7Ru3 NW system, in particular, quantitatively achieved an exchange current density of 0.493 mA/cm2, which is higher than the corresponding data for Pt NWs alone. In addition, the HOR activities follow the same expected trend as their calculated hydrogen binding energy (HBE) values, thereby confirming the critical importance and correlation of HBE with the observed activities.« less

  1. Hydrological conditions determine branched glycerol dialkyl glycerol tetraether distributions in soils of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Huguet, Carme; Menges, Johanna; Fietz, Susanne; Sachse, Dirk; Rosell-Melé, Antoni

    2013-04-01

    Temperature is one of the key environmental factors driving climate change, but past continental temperature records are constrained by the few proxies that can be applied in these environments. The MBT-CBT proxy is based on the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), bacterial membrane lipids in soils1.Since the degree of cyclisation of the GDGTs (CBT) was found to corellate to soil pH, while tindex degree of methylation (MBT) corellates to mean annual temperature and soil pH. a combination of these two indices allows the estimation of mean annual temperature (MAT). However, it has been suggested, that other factors such as the hydrological conditions can also influence the MBT2, although it has never been testet directly. To asses the effect of hydrological conditions on the MBT-CBT a set of 25 soil samples of the Iberian Peninsula covering a temperature range from 10-18°C and a wide range of hydrological regimes was analysed (405 mm to 1455 mm per year) . We found that CBT was significantly correlated to soil pH confirming it even at a regional scale as a robust proxy for soil pH. The MBT was also shown to relate to soil pH, but the the expected relation between MBT and MAT could not be established. In fact, the correlation between MBT and MAT was inverse to the one expected according to previous studies and presented large scatter (R2=0,2). Consequently the MAT estimation using the MBT-CBT proxy leads to an underestimation of MAT, which is most prominent at the dryest sites and reaches up to 24°C. Instead we found a significant correlation between MBT and annual mean precipitation as well as the Aridity Index (AI)3, a parameter quantifying water availability in soils. This suggests that in dry environments or under moisture shortage the influence of the degree of methylation of branched GDGTs is not coupled to temperature but to the degree of water availability. 1. Weijers, J.W.H. et al. 2007. GCA. 71, 703-713. 2. Peterse, F

  2. Soil structure, colloids, and chemical transport as affected by short-term reducing conditions: a laboratory study

    NASA Astrophysics Data System (ADS)

    de-Campos, A. B.; Mamedov, A. I.; Huang, C.; Wagner, L. E.

    2008-12-01

    Upland soils in the Midwestern US often undergo reducing conditions when soils are temporally flooded during the spring and remain water saturated for days or weeks. Short-term reducing conditions change the chemistry of the soil and may affect soil structure and solution chemical transport. The effects of short-term reducing conditions on chemical and physical properties of the soils, colloids, and associated chemical/nutrients transport are still not well understood and was the objective of our study. A biogeochemical reactor was built to achieve reducing conditions. Three cultivated and three uncultivated soils with different organic carbon contents were incubated in the reactor for 1 hour and 3 days under anaerobic conditions. Effects of the redox state on soil structure (pore size distribution) and drainable porosity, colloids mobility, and chemical transport were determined using high energy moisture characteristic and analytical methods. After each treatment, the soil solution was collected for redox potential (Eh), pH, and electrical conductivity (EC) measurements, and chemical analysis of metals (Ca, Mg, K), nutrients (N, P), and dissolved organic carbon. Strongly reducing conditions were achieved after 3 days of incubation and were followed by a decrease in soil porosity and an increase in pH, EC, clay dispersion, swelling, colloids mobility, and associated chemical transport. The trend for each soil depended on their initial structural stability and chemical properties. The structure of cultivated soils and the leaching of nutrients and carbon from uncultivated soils were more sensitive to the redox state. A strong correlation was found between changes in Eh and drainable porosity. The role of short-term reducing conditions on changes in redox sensitive elements, organic matter decomposition, pH, and EC and their influence on soil structure and soil particles or colloids/chemical transport for both soil groups are discussed in the paper. This study

  3. Dissipation of pendimethalin in soil and its residues in chickpea (Cicer arietinum L.) under field conditions.

    PubMed

    Sondhia, Shobha

    2012-11-01

    Disappearance of pendimethalin in the soil of chickpea (Cicer arietinum L.) at 0-110 days, and terminal residues in plant samples have been studied under field conditions. Pendimethalin was applied as pre-emergence herbicide at 750, 350 and 180 g a.i. ha(-1) in winter, in chickpea crop. The dissipation of pendimethalin in the chickpea field soil conditions followed first order kinetics showing a half-life of 11.23 days averaged over all doses. Low pendimethalin residues were found in plant samples. 0.025, 0.015, <0.001 μg g(-1) residues of pendimethalin were found in grains at 750, 350 and 185 g a.i. ha(-1) treatments, respectively. Much lower pendimethalin residues were found in straw viz. 0.015 to <0.001 μg g(-1) at 750, 350 and 185 g a.i. ha(-1) treatments, respectively.

  4. Effect of wetting-drying cycles and fire conditions on runoff and soil loss of a Mediterranean Pale Rendzina

    NASA Astrophysics Data System (ADS)

    Lado, Marcos; Inbar, Assaf; Tenaw, Haim; Stenberg, Marcelo; Ben-Hur, Meni

    2013-04-01

    Wetting and drying cycles have been reported to have a positive effect on soil aggregation and improve the recovery of soil structure after a disturbance. Therefore, after wildfires, it is expected that drying periods between consecutive storms could modify runoff and soil loss patterns. At the same time, different fire conditions may coexist in a location during a wildfire, creating a mosaic of soils affected to different degrees. The objective of this study was to analyze the effect of wetting-drying cycles and various fire conditions on infiltration rate, runoff and soil loss of a Mediterranean soil. Samples from a Pale Rendzina from Birya forest in Northern Israel were subjected to treatments representing some of the soil disturbances that may coexist after a wildfire: unburnt (UB-soil, i.e. not affected by fire); low-moderate severity direct fire (direct fire-DF soil) and; prolonged heating under moderate temperature without direct contact with the flames (oven heated-HT soil). Each soil was placed under a rainfall simulator and exposed to three 80-mm storms separated by drying periods of 72h. Significant differences were found between fire conditions in infiltration rate, runoff and soil loss. Runoff and soil loss were in the following order :HTsoil loss of the HT soil were a result of its higher structural stability, likely emerging from the thermal fusion of clay particles in the aggregates, and from changes in the soil solution that reduced clay dispersion. This was confirmed by data obtained from slaking and dispersion tests. Wetting and drying cycles did not have a positive effect on runoff or soil loss. Total runoff and soil loss from the UB soil remained relatively constant in the three rainstorms, while those of DF and HT soils increased significantly from one rainstorm to the next. Therefore, the differences between fire conditions became smaller as the number of

  5. About climate variabilitiy leading the hydric condition of the soil in the rainfed region of Argentina

    NASA Astrophysics Data System (ADS)

    Pántano, V. C.; Penalba, O. C.

    2013-05-01

    Extreme events of temperature and rainfall have a socio-economic impact in the rainfed agriculture production region in Argentina. The magnitude of the impact can be analyzed through the water balance which integrates the characteristics of the soil and climate conditions. Changes observed in climate variables during the last decades affected the components of the water balance. As a result, a displacement of the agriculture border towards the west was produced, improving the agricultural production of the region. The objective of this work is to analyze how the variability of rainfall and temperature leads the hydric condition of the soil, with special focus on extreme events. The hydric conditions of the soil (HC= Excess- Deficit) were estimated from the monthly water balance (Thornthwaite and Mather method, 1957), using monthly potential evapotranspiration (PET) and monthly accumulated rainfall (R) for 33 stations (period 1970-2006). Information of temperature and rainfall was provided by National Weather Service and the effective capacity of soil water was considered from Forte Lay and Spescha (2001). An agricultural extreme condition occurs when soil moisture and rainfall are inadequate or excessive for the development of the crops. In this study, we define an extreme event when the variable is less (greater) than its 20% and 10% (80% and 90%) percentile. In order to evaluate how sensitive is the HC to water and heat stress in the region, different conditional probabilities were evaluated. There is a weaker response of HC to extreme low PET while extreme low R leads high values of HC. However, this behavior is not always observed, especially in the western region where extreme high and low PET show a stronger influence over the HC. Finally, to analyze the temporal variability of extreme PET and R, leading hydric condition of the soil, the number of stations presenting extreme conditions was computed for each month. As an example, interesting results were

  6. Using NASA UAVSAR Datasets to Link Soil Moisture to Crop Conditions

    NASA Astrophysics Data System (ADS)

    Davitt, A. W. D.; McDonald, K. C.; Azarderakhsh, M.; Winter, J.

    2015-12-01

    California and The Central Valley are experiencing one of that region's worst, persistent droughts, which represents the continuation of a prolonged drought that started in the early 2000's. Due to the continued drought, many agricultural regions in The Central Valley have been experiencing water shortages, negatively impacting agricultural production and the socio-economics of the region. Due to these impacts, there has been an increased incentive to find new ways to conserve water for use in irrigation. Recent advances in remote sensing techniques provide the ability for end users to better understand field conditions so they may make more informed decisions on irrigation timing and amounts. However, a good understanding of soil moisture and its role in crop health and yield is lacking to support informed water management decisions. Though known to be important, a robust understanding of the role of the spatio-temporal patterns in soil moisture linked to crop health is lacking. Remote sensing platforms such as NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) provide the capacity to obtain within-field measurements to estimate within-field and field-to-field variability in soil moisture. UAVSAR radar images acquired from 2010 to 2014 for Yolo County, California are being examined to determine the suitability of high resolution (field scale) multi-temporal L-band radar backscatter imagery for soil moisture assessment and crop conditions through the growing season. By using such data and linking to in-situ meteorology measurements, modeling (MIMICS), and other remote sensing derived datasets (Sentinel, Landsat, MODIS, and TOPS-SIMS), an integrated monitoring system can potentially support the assessment of agricultural field conditions. This allows growers to optimize the use of limited water supplies through informed water management practices, potentially improving crop conditions and yield in a water stressed region.

  7. Predicting watershed acidification under alternate rainfall conditions

    USGS Publications Warehouse

    Huntington, T.G.

    1996-01-01

    The effect of alternate rainfall scenarios on acidification of a forested watershed subjected to chronic acidic deposition was assessed using the model of acidification of groundwater in catchments (MAGIC). The model was calibrated at the Panola Mountain Research Watershed, near Atlanta, Georgia, U.S.A. using measured soil properties, wet and dry deposition, and modeled hydrologic routing. Model forecast simulations were evaluated to compare alternate temporal averaging of rainfall inputs and variations in rainfall amount and seasonal distribution. Soil water alkalinity was predicted to decrease to substantially lower concentrations under lower rainfall compared with current or higher rainfall conditions. Soil water alkalinity was also predicted to decrease to lower levels when the majority of rainfall occurred during the growing season compared with other rainfall distributions. Changes in rainfall distribution that result in decreases in net soil water flux will temporarily delay acidification. Ultimately, however, decreased soil water flux will result in larger increases in soil- adsorbed sulfur and soil-water sulfate concentrations and decreases in alkalinity when compared to higher water flux conditions. Potential climate change resulting in significant changes in rainfall amounts, seasonal distribution of rainfall, or evapotranspiration will change net soil water flux and, consequently, will affect the dynamics of the acidification response to continued sulfate loading.

  8. Effect of some antioxidants on canola plants grown under soil salt stress condition.

    PubMed

    Sakr, M T; Arafa, A A

    2009-04-01

    In this study, two field experiments were carried out during the two growing seasons (2005-2006 and 2006-2007) to investigate the role of some applied antioxidants (spermine 10 mg L(-1) and ascorbic acid 200 mg L(-1)) in counteracting the harmful effect of soil salinity stress (10.1 or 14.6 dS m(-1)) on canola plants. Growth characters, yield and its components as well as biochemical constituents were studied in the two growing seasons. The results showed that all growth characters including; plant height, leaves number and area/plant, shoot and root dry weight as well as yield and its components including; fruit number/plant, number of fruiting branches, seed number/fruit, seed yield/plant and seed oil content of canola plant were decreased with increasing soil salt level (A2) comparing with (A1). On the other hand, applied antioxidants spermine 10 mg L(-1) and ascorbic acid 200 mg L(-1)) increased growth and yield of canola plant during the two growing seasons. However, the applied antioxidants were more effective under the first soil salt condition (A1) soil salt stress levels (A2) decreased each of photosynthetic pigments, K and P contents, while increased proline, soluble sugar, ascorbic acid, Na and Cl contents compared with (A1). On the other hand, applied antioxidants increased each of photosynthetic pigments, proline, soluble sugar, N, K and P contents, while decreased Na and Cl contents in canola plant under soil salt stress (A1 and A2) during the two growing seasons. It could be concluded that applied antioxidants could counteract the harmful effect of salt soil stress on growth, yield and biochemical constituents of canola plant.

  9. Pore Water Pressure Response of a Soil Subjected to Traffic Loading under Saturated and Unsaturated Conditions

    NASA Astrophysics Data System (ADS)

    Cary, Carlos

    This study presents the results of one of the first attempts to characterize the pore water pressure response of soils subjected to traffic loading under saturated and unsaturated conditions. It is widely known that pore water pressure develops within the soil pores as a response to external stimulus. Also, it has been recognized that the development of pores water pressure contributes to the degradation of the resilient modulus of unbound materials. In the last decades several efforts have been directed to model the effect of air and water pore pressures upon resilient modulus. However, none of them consider dynamic variations in pressures but rather are based on equilibrium values corresponding to initial conditions. The measurement of this response is challenging especially in soils under unsaturated conditions. Models are needed not only to overcome testing limitations but also to understand the dynamic behavior of internal pore pressures that under critical conditions may even lead to failure. A testing program was conducted to characterize the pore water pressure response of a low plasticity fine clayey sand subjected to dynamic loading. The bulk stress, initial matric suction and dwelling time parameters were controlled and their effects were analyzed. The results were used to attempt models capable of predicting the accumulated excess pore pressure at any given time during the traffic loading and unloading phases. Important findings regarding the influence of the controlled variables challenge common beliefs. The accumulated excess pore water pressure was found to be higher for unsaturated soil specimens than for saturated soil specimens. The maximum pore water pressure always increased when the high bulk stress level was applied. Higher dwelling time was found to decelerate the accumulation of pore water pressure. In addition, it was found that the higher the dwelling time, the lower the maximum pore water pressure. It was concluded that upon further

  10. Toluene biodegradation rates in unsaturated soil systems versus liquid batches and their relevance to field conditions.

    PubMed

    Picone, Sara; Grotenhuis, Tim; van Gaans, Pauline; Valstar, Johan; Langenhoff, Alette; Rijnaarts, Huub

    2013-09-01

    Contaminant biodegradation in unsaturated soils may reduce the risks of vapor intrusion. However, the reported rates show large variability and are often derived from slurry experiments that are not representative of unsaturated conditions. Here, different laboratory setups are used to derive the biodegradation capacity of an unsaturated soil layer through which gaseous toluene migrates from the water table upwards. Experiments in static unsaturated soil microcosms at 6-30 % water-filled porosity (WFP) and unsaturated soil columns at 9, 14, and 27 % WFP were compared with liquid batches containing the same culture of Alicycliphilus denitrificans. The biodegradation rates for the liquid batches were orders of magnitude lower than for the other setups. Hence, liquid batches do not necessarily reflect optimal conditions for bacteria; either oxygen or toluene mass transfer at the cell scale or the absence of soil-water-air interfaces seemed to be limiting bacterial activity. For the column setup, the rates were limited by mass supply. The microcosm results could be described by apparent first-order biodegradation constants that increased with WFP or through a numerical model that included biodegradation as a first-order process taking place in the liquid phase only. The model liquid phase first-order rates varied between 6.25 and 20 h(-1) and were not related to the water content. Substrate availability was the primary factor limiting bioactivity, with evidence for physiological stress at the lowest water-filled porosity. The presented approach is useful to derive liquid phase biodegradation rates from experimental data and to include biodegradation in vapor intrusion models.

  11. Transgenic petunia with the iron(III)-phytosiderophore transporter gene acquires tolerance to iron deficiency in alkaline environments.

    PubMed

    Murata, Yoshiko; Itoh, Yoshiyuki; Iwashita, Takashi; Namba, Kosuke

    2015-01-01

    Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as mugineic acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic acids and the specific iron(III)-mugineic acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2'-deoxymugineic acid complex, free 2'-deoxymugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2'-deoxymugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to diverse

  12. Effects of long-term continuous cropping on soil nematode community and soil condition associated with replant problem in strawberry habitat

    PubMed Central

    Li, Xingyue; Lewis, Edwin E.; Liu, Qizhi; Li, Heqin; Bai, Chunqi; Wang, Yuzhu

    2016-01-01

    Continuous cropping changes soil physiochemical parameters, enzymes and microorganism communities, causing “replant problem” in strawberry cultivation. We hypothesized that soil nematode community would reflect the changes in soil conditions caused by long-term continuous cropping, in ways that are consistent and predictable. To test this hypothesis, we studied the soil nematode communities and several soil parameters, including the concentration of soil phenolic acids, organic matter and nitrogen levels, in strawberry greenhouse under continuous-cropping for five different durations. Soil pH significantly decreased, and four phenolic acids, i.e., p-hydroxybenzoic acid, ferulic acid, cinnamic acid and p-coumaric acid, accumulated with time under continuous cropping. The four phenolic acids were highly toxic to Acrobeloides spp., the eudominant genus in non-continuous cropping, causing it to reduce to a resident genus after seven-years of continuous cropping. Decreased nematode diversity indicated loss of ecosystem stability and sustainability because of continuous-cropping practice. Moreover, the dominant decomposition pathway was altered from bacterial to fungal under continuous cropping. Our results suggest that along with the continuous-cropping time in strawberry habitat, the soil food web is disturbed, and the available plant nutrition as well as the general health of the soil deteriorates; these changes can be indicated by soil nematode community. PMID:27506379

  13. Effects of long-term continuous cropping on soil nematode community and soil condition associated with replant problem in strawberry habitat

    NASA Astrophysics Data System (ADS)

    Li, Xingyue; Lewis, Edwin E.; Liu, Qizhi; Li, Heqin; Bai, Chunqi; Wang, Yuzhu

    2016-08-01

    Continuous cropping changes soil physiochemical parameters, enzymes and microorganism communities, causing “replant problem” in strawberry cultivation. We hypothesized that soil nematode community would reflect the changes in soil conditions caused by long-term continuous cropping, in ways that are consistent and predictable. To test this hypothesis, we studied the soil nematode communities and several soil parameters, including the concentration of soil phenolic acids, organic matter and nitrogen levels, in strawberry greenhouse under continuous-cropping for five different durations. Soil pH significantly decreased, and four phenolic acids, i.e., p-hydroxybenzoic acid, ferulic acid, cinnamic acid and p-coumaric acid, accumulated with time under continuous cropping. The four phenolic acids were highly toxic to Acrobeloides spp., the eudominant genus in non-continuous cropping, causing it to reduce to a resident genus after seven-years of continuous cropping. Decreased nematode diversity indicated loss of ecosystem stability and sustainability because of continuous-cropping practice. Moreover, the dominant decomposition pathway was altered from bacterial to fungal under continuous cropping. Our results suggest that along with the continuous-cropping time in strawberry habitat, the soil food web is disturbed, and the available plant nutrition as well as the general health of the soil deteriorates; these changes can be indicated by soil nematode community.

  14. Effects of long-term continuous cropping on soil nematode community and soil condition associated with replant problem in strawberry habitat.

    PubMed

    Li, Xingyue; Lewis, Edwin E; Liu, Qizhi; Li, Heqin; Bai, Chunqi; Wang, Yuzhu

    2016-01-01

    Continuous cropping changes soil physiochemical parameters, enzymes and microorganism communities, causing "replant problem" in strawberry cultivation. We hypothesized that soil nematode community would reflect the changes in soil conditions caused by long-term continuous cropping, in ways that are consistent and predictable. To test this hypothesis, we studied the soil nematode communities and several soil parameters, including the concentration of soil phenolic acids, organic matter and nitrogen levels, in strawberry greenhouse under continuous-cropping for five different durations. Soil pH significantly decreased, and four phenolic acids, i.e., p-hydroxybenzoic acid, ferulic acid, cinnamic acid and p-coumaric acid, accumulated with time under continuous cropping. The four phenolic acids were highly toxic to Acrobeloides spp., the eudominant genus in non-continuous cropping, causing it to reduce to a resident genus after seven-years of continuous cropping. Decreased nematode diversity indicated loss of ecosystem stability and sustainability because of continuous-cropping practice. Moreover, the dominant decomposition pathway was altered from bacterial to fungal under continuous cropping. Our results suggest that along with the continuous-cropping time in strawberry habitat, the soil food web is disturbed, and the available plant nutrition as well as the general health of the soil deteriorates; these changes can be indicated by soil nematode community. PMID:27506379

  15. [Ammonia volatilization of slow release compound fertilizer in different soils water conditions].

    PubMed

    Hu, Xiao-feng; Wang, Zheng-yin; You, Yuan; Li, Jing-chao

    2010-08-01

    By using venting method incubation experiment, we studied the ammonia volatilization and kinetics characteristics of uncoated slowed release compound fertilizer (SRF) under different soil water conditions and the growth and nitrogen utilization efficiency of rice in pot experiment. Results indicated that the ammonia volatilization of SRF under waterflooding reached the peak ahead of 3-4 days compared to the moist treatment. The peak and accumulation of ammonia volatilization in the waterflooding treatments were higher than those under the moist condition. SRF could significantly reduce total ammonia volatilization compared to the common compound fertilizer (CCF), reduced by 50.6% and 22.8% in the moist treatment and reduced by 24.2% and 10.4% in the waterflooding treatment,but the loss of ammonia volatilization of SRF was higher significantly than that of the coated fertilizer (CRF). Ammonia volatilization increased with the increasing of fertilizer application. The dynamics of ammonia volatilization of SRF could be quantitatively described with three equations: the first order kinetics equation, Elovich equation and parabola equation. Compared to moist condition, the biomass of rice plant in SRF, CCF and SRF treatments increased by 67.86%, 78.25% and 48.75%, and nitrogen utilization efficiency increased by 57.73%, 80.70% and 12.06% under waterflooding condition, respectively. Comparing with CCF, nitrogen utilization efficiency in SRF treatment improved by 59.10% and 10.40% under two soil moisture conditions. SRF could reduce ammonia volatilization and improve biomass and nitrogen utilization efficiency.

  16. Carbon and Nitrogen dynamics in forest soils depending on light conditions and tree species

    NASA Astrophysics Data System (ADS)

    Veselinovic, Bojana; Hager, Herbert

    2013-04-01

    Climate change mitigation actions under the Kyoto Protocol apply among other decreases of CO2-emissions and/or increases of carbon (C) stocks. As soils represent the second biggest C-reservoir on Earth, an exact estimation of the stocks and reliable knowledge on C-dynamics in forest soils is of high importance. Anyhow, here, the accurate GHG-accounting, emission reductions and increase in C stocks is hampered due to lack of reliable data and solid statistical methods for the factors which influence C-sequestration in and its release from these systems. In spite of good progress in the scientific research, these factors are numerous and diverse in their interactions. This work focuses on influence of the economically relevant tree species - Picea abies, Fagus sylvatica and Quercus spp. - and light conditions on forest floor and mineral soil C and N dynamics in forest soils. Spruce monocultures have been widely used management practices in central European forests during the past century. Such stands are in lower altitudes and on heavy and water logged soils unstable and prone to disturbances, especially to windthrows. We hypothesize that windthrow areas loose C & N and that the establishment of the previous nutrient stocks is, if at all, only possible to be reached over the longer periods of time. We research also how the increased OM depletion affects the change of C & N stocks in forest floor vs. mineral soil. Conversion of such secondary spruce monocultures to site adequate beech and oak forests may enable higher stocks allocated predominantly as stable organic carbon and as plant available nitrogen. For this purpose sites at 300-700 m altitude with planosols were chosen in the region of the Northern Alpine Foothills. A false chronosequence approach was used in order to evaluate the impacts of the tree species and change in light conditions on dynamic of C & N in the forest floor and mineral soil, over the period 0-100 (for oak 120 y.) years. The C- and N

  17. Comparison of four soil moisture sensor types under field conditions in Switzerland

    NASA Astrophysics Data System (ADS)

    Mittelbach, Heidi; Lehner, Irene; Seneviratne, Sonia I.

    2012-04-01

    SummaryMany environmental and hydrological applications require knowledge about soil moisture. Its measurement accuracy is known to depend on the sensor technique, which is sensitive to soil characteristics such as texture, temperature, bulk density and salinity. However, the calibration functions provided by instrument manufacturers are generally developed under laboratory conditions, and their accuracy for field applications is rarely investigated, in particular over long time periods and in comparison with other sensors types. In this paper, four side-by-side profile soil moisture measurements down to 110 cm using three low-cost sensors and one high-accuracy and high-cost time domain reflectometry (TDR) sensor are compared over a 2-year period at a clay loam site in Switzerland. The low-cost instruments include the (1) 10HS (Decagon Devices, United States), (2) CS616 (Campbell Scientific, United States), and (3) SISOMOP (SMG University of Karlsruhe, Germany) sensors, which are evaluated against the (4) TDR-based TRIME-IT/-EZ (IMKO GmbH, Germany) sensors. For the comparison, the calibration functions provided by the manufacturers are applied for each sensor type. The sensors are evaluated based on daily data regarding their representation of the volumetric water content (VWC) and its anomalies, as well as the respective temperature dependency of the measurements. Furthermore, for each sensor type the actual evapotranspiration is estimated using the soil water balance approach and compared with measurements from a weighing lysimeter. It is shown that the root mean square difference (RMSD) of VWC for the low-cost sensors compared to the TDR measurements are up to 0.3 m3/m3, with highest values in near-surface layers. However, the RMSD for the VWC anomalies are lower compared to those for absolute values. We conclude that under the studied conditions none of the evaluated low-cost sensors has a level of performance consistent with the respective manufacturer

  18. Mobilization and Release of colloidal Carbon from a Soil Column Under Redox Oscillation Condition

    NASA Astrophysics Data System (ADS)

    Afsar, M. Z.; Jin, Y.

    2015-12-01

    Dissolved organic matter (DOM), the most mobile form of carbon (C), strongly influences the cycling, distribution and behavior of C in soil. In wetlands, the reductive dissolution of iron and manganese oxy-hydroxides releases large quantities of DOM into the soil solution. The objective of this study is to quantify the changes in aqueous organic carbon concentration in different sized fractions induced by reduction of iron and increase in pH. Twenty four cm long soil columns were prepared. Columns were run under oxic (as control) and anoxic conditions. Two platinum redox probes were inserted at 10 and 17 cm depths from the soil surface to monitor the redox status of the column. Anoxic and oxic conditions were maintained by flushing with either nitrogen or oxygen gas through the soil. No additional organic sources were added. After 35 days of anoxic environment, column leachate samples were separated by differential centrifugation into five colloidal sized fractions (<450 nm, <220 nm, <100 nm, <50 nm and <2.3 nm). Immediately after the 1st reduction half cycle, the leachate samples were collected inside the glove box and the soil columns were flushed with oxygen to prepare for 2nd reduction half cycle. After 1st reduction half cycle, the pH, ionic strength and aqueous (Fe2+) concentration of the column extracts were increased whereas the Eh value was decreased. The range of pH, Eh, ionic strength and concentration of Fe2+ was 6.38 to 6.91, -219 to -275 mV, 13.74 to 18.84 mM and 1.8 to 3.41 mg L-1, respectively. Following the anoxic incubation, the total desorbed C was increased up to 139 mg L-1. The distribution of C across the five particle size fractions was 3.68-11.73% (> 450 nm), 0.59-5.12% (450-220 nm), 0.45-4.91% (220-100 nm), 0.18-2.91% (100-50 nm), 15.48-35.23% (50 nm - 2.3 nm) and 49.15-63.94% (<2.3 nm). The preliminary results confirmed the release of more nanoparticulate (50-2.3 nm) and truly dissolved (<2.3 nm) organic matter from the anoxic soil column

  19. Nitrous oxide emissions in southern Poland from agricultural soils under various tillage conditions and from urban soils under strong anthropopression

    NASA Astrophysics Data System (ADS)

    Galkowski, M.; Bartyzel, J.; Zięba, D.; Ciaciek, K.; Nęcki, J. M.

    2015-12-01

    We present the results of field measurements performed at: (i) the agricultural sites managed by Institute of Plant Acclimatization and Husbandry (ZDHAR) in Grodkowice (Malopolska, Poland), and (ii) the urban sites located in Kraków, Poland. For agricultural measurements, several sites have been selected for measurements of N2O emissions during two campaigns - in spring and autumn 2014. The investigated crops were chosen to represent the regional agriculture and included wheat, canola and maize under various tillage conditions, as well as an uncultivated grassland as a control site. For urban environment, measurement campaigns have been performed at the university's campus lawn and at a large urban meadow, both located in the centre of Kraków agglomeration. The sites were chosen to be representative of the urban green areas typical of Central Europe. The static chamber method was chosen to quantify soil-atmosphere N2O fluxes. Chamber enclosures have been performed every 3-5 days, depending on the conditions prevailing at the sites during the intermediate periods. From each enclosure, five 50-ml air samples have been collected for subsequent analysis of nitrous oxide concentrations. Well-established gas chromatography methods, with a precision of a single N2O measurement better than 0.5 ppb were employed. The measured concentrations were then used in a linear emission model to calculate N2O fluxes. Results of agricultural campaigns show large variability of N2O emissions, with maximum fluxes in the order of 120 ng N-N2O m-2 s-1, driven mainly by availability of nitrogen in soil and water. For fertilized sites, largest emissions values were observed several days after the rainfall events. Notable differences between sites under alternative tillage techniques have been observed. Observations at the urban sites revealed significant fluxes of N2O, with average daily values in some cases exceeding those observed at agricultural fields.

  20. [CO2 response process and its simulation of Prunus sibirica photosynthesis under different soil moisture conditions].

    PubMed

    Wu, Qin; Zhang, Guang-Can; Pei, Bin; Xu, Zhi-Qiang; Zhao, Yu; Fang, Li-Dong

    2013-06-01

    Taking the two-year old potted Prunus sibirica seedlings as test materials, and using CIRAS-2 photosynthetic system, this paper studied the CO2 response process of P. sibirica photosynthesis in semi-arid loess hilly region under eight soil moisture conditions. The CO2 response data of P. sibirica were fitted and analyzed by rectangular hyperbola model, exponential equation, and modified rectangular hyperbola model. Meanwhile, the quantitative relationships between the photosynthesis and the soil moisture were discussed. The results showed that the CO2 response process of P. sibirica photosynthesis had obvious response characteristics to the soil moisture threshold. The relative soil water content (RWC) required to maintain the higher photosynthetic rate (P(n)) and carboxylation efficiency (CE) of P. sibirica was in the range of 46.3%-81.9%. In this RWC range, the photosynthesis did not appear obvious CO2 saturated inhibition phenomenon. When the RWC exceeded this range, the photosynthetic capacity (P(n max)), CE, and CO2 saturation point (CSP) decreased evidently. Under different soil moisture conditions, there existed obvious differences among the three models in simulating the CO2 response data of P. sibirica. When the RWC was in the range of 46.3%-81.9%, the CO2 response process and the characteristic parameters such as CE, CO2 compensation point (see symbol), and photorespiration rate (R(p)) could be well fitted by the three models, and the accuracy was in the order of modified rectangular hyperbola model > exponential equation > rectangular hyperbola model. When the RWC was too high or too low, namely, the RWC was > 81.9% or < 46.3%, only the modified rectangular hyperbola model could well fit the CO2 response process and the characteristic parameters. It was suggested that when the RWC was from 46.3% to 81.9%, the photosynthetic efficiency of P. sibirica was higher, and, as compared with rectangular hyperbola model and exponential equation, modified

  1. Copper(II) directs formation of toxic amorphous aggregates resulting in inhibition of hen egg white lysozyme fibrillation under alkaline salt-mediated conditions.

    PubMed

    Ghosh, Sudeshna; Pandey, Nitin K; Banerjee, Priyanka; Chaudhury, Koel; Nagy, Nóra Veronika; Dasgupta, Swagata

    2015-01-01

    Hen egg white lysozyme (HEWL) adopts a molten globule-like state at high pH (~12.75) and is found to form amyloid fibrils at alkaline pH. Here, we report that Cu(II) inhibits self-association of HEWL at pH 12.75 both at 37 and 65 °C. A significant reduction in Thioflavin T fluorescence intensity, attenuation in β-sheet content and reduction in hydrophobic exposure were observed with increasing Cu(II) stoichiometry. Electron paramagnetic resonance spectroscopy suggests a 4N type of coordination pattern around Cu(II) during fibrillation. Cu(II) is also capable of altering the cytotoxicity of the proteinaceous aggregates. Fibrillar species of diverse morphology were found in the absence of Cu(II) with the generation of amorphous aggregates in the presence of Cu(II), which are more toxic compared to the fibrils alone.

  2. Influence of climatic conditions and soil type on 99TcO4- uptake by rye grass.

    PubMed

    Echevarria, Guillaume; Morel, Jean Louis; Florentin, Louis; Leclerc-Cessac, Elisabeth

    2003-01-01

    Climatic changes over the long term will modify significantly the biosphere, with glaciation events probably taking place in the next 100 000 years. This is important to safety assessments of nuclear waste disposal facilities that contain high-level and long-lived waste. The soils will evolve toward new situations, and their properties will be consequently modified (e.g. an increase of soil organic matter may be expected in a cooler climate). These changes in soil properties would affect the mobility and the soil-to-plant transfer of radionuclides such as (99)Tc. This study aimed at simulating the cooling of climatic conditions for soils representative of a Jurassic limestone plateau, and the effect on transfer parameters of (99)TcO(4)(-) in the soil-plant systems was investigated. The cooler conditions were simulated by increasing elevation, a surrogate for climate change. Soils were sampled in similar geological background and topography at different elevations in the north east of France (Lorraine and Jura). Soil/solution distribution coefficients (K(d)) of (99)TcO(4)(-) were measured on soil samples in short-term batch experiments with 1:10 soil:solution ratio. Rye grass was grown on the soils spiked with (99)TcO(4)(-) at temperature regimes adapted to each soil. Also, two different temperature regimes (cold and temperate) were applied to one soil to test the effect of plant physiology and evapotranspiration on (99)TcO(4)(-) uptake. K(d) values did not show significant differences among soils in aerobic conditions, and were not significantly different from 0. During plant culture, reduction of (99)Tc was never totally achieved in soils, including in a peaty OM soil. Concentration ratios (CR) were calculated on a dry weight basis and ranged from 20 to 370. CR were always higher in high temperature regimes than in cold temperatures. They were also inversely correlated with soil organic matter (OM) content. A decrease of CR values from 5 to 10-fold was observed

  3. Selecting indicators of soil, microbial, and plant conditions to understand ecological changes in Georgia pine forests

    SciTech Connect

    Dale, Virginia H; Garten Jr, Charles T; Wolfe, Amy K; Sobek, Edward A

    2008-11-01

    Characterizing how resource use and management activities affect ecological conditions is necessary to document and understand anthropogenic changes in ecological systems. Resource managers on military installations have the delicate task of balancing the training needs of soldiers effectively with the need to maintain a high quality of ecological conditions. This study considers ways that ecological indicators can provide information on impacts that training has on environmental characteristics that occur at different scales and in different sectors of the environment. The characteristics examined include soil chemistry, soil microbes, and vegetation. A discriminant function analysis was conducted to determine whether ecological indicators could differentiate among different levels of military use. A combination of 10 indicators explained 90% of the variation among plots from five different military use levels. Results indicated that an appropriate suite of ecological indicators for military resource managers includes soil, microbial, and vegetation characteristics. Since many of these indicators are related, managers at this location potentially have freedom to choose indicators that are relatively easy to measure, without sacrificing information.

  4. Arsenic mobility in soils contaminated with metallurgical wastes as a function of variable chemical conditions

    NASA Astrophysics Data System (ADS)

    Garcia Payne, D. G.; Villalobos, M.; Ceniceros, A.; Lopez, J. L.; Gutierrez, M.

    2008-12-01

    Arsenic is a pervasive contaminant of natural aqueous systems, such as groundwater and soils, its sources being both natural and anthropogenic. The present investigation was performed on soils contaminated with residues from ore processing activities and revealed the presence of arsenate [As(V)] species with a very low mobility, through natural attenuation processes. The stability of this attenuation was investigated by varying two specific equilibrium chemical conditions: pH and presence of bicarbonate ions. One-unit changes in equilibrium pH generally caused small increases in As mobility, whereas the presence of bicarbonate ions considerably increased this mobility. The results were compared to thermodinamic simulations of equilibrium conditions using the total elemental composition of each individual soil, but excluding sorption reactions. Close matches between experimental data and simulations revealed the predominance of solubility-controlled As mobility via heavy-metal arsenate solid formation. Bicarbonate ions were found to be highly unsuitable for extraction of sorbed arsenate fractions due to indirect As release from solid arsenates, via heavy-metal carbonate precipitation processes.

  5. Ammonia-oxidizing bacteria and archaea grow under contrasting soil nitrogen conditions.

    PubMed

    Di, Hong J; Cameron, Keith C; Shen, Ju-Pei; Winefield, Chris S; O'Callaghan, Maureen; Bowatte, Saman; He, Ji-Zheng

    2010-06-01

    Nitrification is a key process of the nitrogen (N) cycle in soil with major environmental implications. The recent discovery of ammonia-oxidizing archaea (AOA) questions the traditional assumption of the dominant role of ammonia-oxidizing bacteria (AOB) in nitrification. We investigated AOB and AOA growth and nitrification rate in two different layers of three grassland soils treated with animal urine substrate and a nitrification inhibitor [dicyandiamide (DCD)]. We show that AOB were more abundant in the topsoils than in the subsoils, whereas AOA were more abundant in one of the subsoils. AOB grew substantially when supplied with a high dose of urine substrate, whereas AOA only grew in the Controls without the urine-N substrate. AOB growth and the amoA gene transcription activity were significantly inhibited by DCD. Nitrification rates were much higher in the topsoils than in the subsoils and were significantly related to AOB abundance, but not to AOA abundance. These results suggest that AOB and AOA prefer different soil N conditions to grow: AOB under high ammonia (NH(3)) substrate and AOA under low NH(3) substrate conditions.

  6. Successional stage of biological soil crusts: an accurate indicator of ecohydrological condition

    USGS Publications Warehouse

    Belnap, Jayne; Wilcox, Bradford P.; Van Scoyoc, Matthew V.; Phillips, Susan L.

    2013-01-01

    Biological soil crusts are a key component of many dryland ecosystems. Following disturbance, biological soil crusts will recover in stages. Recently, a simple classification of these stages has been developed, largely on the basis of external features of the crusts, which reflects their level of development (LOD). The classification system has six LOD classes, from low (1) to high (6). To determine whether the LOD of a crust is related to its ecohydrological function, we used rainfall simulation to evaluate differences in infiltration, runoff, and erosion among crusts in the various LODs, across a range of soil depths and with different wetting pre-treatments. We found large differences between the lowest and highest LODs, with runoff and erosion being greatest from the lowest LOD. Under dry antecedent conditions, about 50% of the water applied ran off the lowest LOD plots, whereas less than 10% ran off the plots of the two highest LODs. Similarly, sediment loss was 400 g m-2 from the lowest LOD and almost zero from the higher LODs. We scaled up the results from these simulations using the Rangeland Hydrology and Erosion Model. Modelling results indicate that erosion increases dramatically as slope length and gradient increase, especially beyond the threshold values of 10 m for slope length and 10% for slope gradient. Our findings confirm that the LOD classification is a quick, easy, nondestructive, and accurate index of hydrological condition and should be incorporated in field and modelling assessments of ecosystem health.

  7. Quantifying the timescales over which exogenous and endogenous conditions affect soil respiration.

    PubMed

    Barron-Gafford, Greg A; Cable, Jessica M; Bentley, Lisa Patrick; Scott, Russell L; Huxman, Travis E; Jenerette, G Darrel; Ogle, Kiona

    2014-04-01

    Understanding how exogenous and endogenous factors and above-ground-below-ground linkages modulate carbon dynamics is difficult because of the influences of antecedent conditions. For example, there are variable lags between above-ground assimilation and below-ground efflux, and the duration of antecedent periods are often arbitrarily assigned. Nonetheless, developing models linking above- and below-ground processes is crucial for estimating current and future carbon dynamics. We collected data on leaf-level photosynthesis (Asat ) and soil respiration (Rsoil ) in different microhabitats (under shrubs vs under bunchgrasses) in the Sonoran Desert. We evaluated timescales over which endogenous and exogenous factors control Rsoil by analyzing data in the context of a semimechanistic temperature-response model of Rsoil that incorporated effects of antecedent exogenous (soil water) and endogenous (Asat ) conditions. For both microhabitats, antecedent soil water and Asat significantly affected Rsoil , but Rsoil under shrubs was more sensitive to Asat than that under bunchgrasses. Photosynthetic rates 1 and 3 d before the Rsoil measurement were most important in determining current-day Rsoil under bunchgrasses and shrubs, respectively, indicating a significant lag effect. Endogenous and exogenous controls are critical drivers of Rsoil , but the relative importance and the timescale over which each factor affects Rsoil depends on above-ground vegetation and ecosystem structure characteristics.

  8. Plant nutrients do not covary with soil nutrients under changing climatic conditions

    NASA Astrophysics Data System (ADS)

    Luo, Wentao; Elser, James J.; Lü, Xiao-Tao; Wang, Zhengwen; Bai, Edith; Yan, Caifeng; Wang, Chao; Li, Mai-He; Zimmermann, Niklaus E.; Han, Xingguo; Xu, Zhuwen; Li, Hui; Wu, Yunna; Jiang, Yong

    2015-08-01

    Nitrogen (N) and phosphorus (P) play vital roles in plant growth and development. Yet how climate regimes and soil fertility influence plant N and P stoichiometry is not well understood, especially in the belowground plant parts. Here we investigated plant aboveground and belowground N and P concentrations ([N] and [P]) and their stoichiometry in three dominant genera along a 2200 km long climatic gradient in northern China. Results showed that temperature explained more variation of [N] and [P] in C4 plants, whereas precipitation exerted a stronger influence on [N] and [P] in C3 plants. Both plant aboveground and belowground [N] and [P] increased with decreasing precipitation, and increasing temperatures yet were negatively correlated with soil [N] and [P]. Plant N:P ratios were unrelated with all climate and soil variables. Plant aboveground and belowground [N] followed an allometric scaling relationship, but the allocation of [P] was isometric. These results imply that internal processes stabilize plant N:P ratios and hence tissue N:P ratios may not be an effective parameter for predicting plant nutrient limitation. Our results also imply that past positive relationships between plant and nutrient stocks may be challenged under changing climatic conditions. While any modeling would need to be able to replicate currently observed relationships, it is conceivable that some relationships, such as those between temperature or rainfall and carbon:nutrient ratios, should be different under changing climatic conditions.

  9. Roles of Arbuscular Mycorrhizal Fungi and Soil Abiotic Conditions in the Establishment of a Dry Grassland Community

    PubMed Central

    Knappová, Jana; Pánková, Hana; Münzbergová, Zuzana

    2016-01-01

    Background 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. Aims and Methods 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. Key Results 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

  10. Biochar carbon sequestration and downward translocation in contrasting soils under field conditions in Australia

    NASA Astrophysics Data System (ADS)

    Pal Singh, Bhupinder; Fang, Yunying; Boersma, Mark; Matta, Pushpinder; Van Zwieten, Lukas; Macdonald, Lynne

    2014-05-01

    Carbon (C) sequestration potential of biochar depends on its stability and stabilisation of native or added organic C in soil. However, the processes of biochar degradation, fate in soil organic matter pools, and downward translocation in the soil profile, and the influence of biochar on emissions or stabilisation of native organic C sources are poorly understood under field conditions. An Eucalyptus saligna green-waste biochar (δ13C -36.6o; total C 66.8%) produced by slow pyrolysis at 450° C was applied at 29.2 t ha-1 to 10-cm depth in