Water potential in soil and Atriplex nummularia (phytoremediator halophyte) under drought and salt stresses.

PubMed

de Melo, Hidelblandi Farias; de Souza, Edivan Rodrigues; de Almeida, Brivaldo Gomes; Mulas, Maurizio

2018-02-23

Atriplex nummularia is a halophyte widely employed to recover saline soils and was used as a model to evaluate the water potentials in the soil-plant system under drought and salt stresses. Potted plants grown under 70 and 37% of field capacity irrigated with solutions of NaCl and of a mixture of NaCl, KCl, MgCl 2 and CaCl 2 reproducing six electrical conductivity (EC): 0, 5, 10, 20, 30, and 40 dS m -1 . After 100 days, total water (Ψ w, plant ) and osmotic (Ψ o, plant ) potentials at predawn and midday and Ψ o, soil , matric potential (Ψ m, soil ) and Ψ w, soil were determined. The type of ion in the irrigation water did not influence the soil potential, but was altered by EC. The soil Ψ o component was the largest contributor to Ψ w, soil . Atriplex is surviving ECs close to 40 dS m -1 due to the decrease in the Ψ w . The plants reached a Ψ w of approximately -8 MPa. The water potentials determined for different moisture levels, EC levels and salt types showed huge importance for the management of this species in semiarid regions and can be used to recover salt affected soils.

Trend Analysis of Soil Salinity in Different Land Cover Types Using Landsat Time Series Data (case Study Bakhtegan Salt Lake)

NASA Astrophysics Data System (ADS)

Taghadosi, M. M.; Hasanlou, M.

2017-09-01

Soil salinity is one of the main causes of desertification and land degradation which has negative impacts on soil fertility and crop productivity. Monitoring salt affected areas and assessing land cover changes, which caused by salinization, can be an effective approach to rehabilitate saline soils and prevent further salinization of agricultural fields. Using potential of satellite imagery taken over time along with remote sensing techniques, makes it possible to determine salinity changes at regional scales. This study deals with monitoring salinity changes and trend of the expansion in different land cover types of Bakhtegan Salt Lake district during the last two decades using multi-temporal Landsat images. For this purpose, per-pixel trend analysis of soil salinity during years 2000 to 2016 was performed and slope index maps of the best salinity indicators were generated for each pixel in the scene. The results of this study revealed that vegetation indices (GDVI and EVI) and also salinity indices (SI-1 and SI-3) have great potential to assess soil salinity trends in vegetation and bare soil lands respectively due to more sensitivity to salt features over years of study. In addition, images of May had the best performance to highlight changes in pixels among different months of the year. A comparative analysis of different slope index maps shows that more than 76% of vegetated areas have experienced negative trends during 17 years, of which about 34% are moderately and highly saline. This percent is increased to 92% for bare soil lands and 29% of salt affected soils had severe salinization. It can be concluded that the areas, which are close to the lake, are more affected by salinity and salts from the lake were brought into the soil which will lead to loss of soil productivity ultimately.

Effects of Salt Accumulation in Soil by Evaporation on Unsaturated Soil Hydraulic Properties

NASA Astrophysics Data System (ADS)

Liu, Y.; Liu, Q.

2017-12-01

Soil salinization is one type of soil degradation caused by saline groundwater evaporation. Salt accumulation in the soil will change the pore structure of soil, which should change the unsaturated soil hydraulic properties including the soil water characteristic curve (SWCC). To investigate the effect of salt accumulation on the SWCC and find the best suitable SWCC model to characterize the relationship of soil moisture and soil matrix potential, we have conducted laboratory SWCC experiments with the soil columns saturated by NaCl solution with different concentration (deionized water, 3 g/L, 15 g/L, 50 g/L, 100 g/L and 200 g/L). As the concentration of initial solution increases, the matrix potential corresponding to the same moisture increases. As the water was evaporated, the salt would precipitate in soil continuously, which would decrease the porosity of soils and increase the negative pressure of soils. With higher initial concentration, the more salt accumulation caused the more residual water content in the soils. For van Genuchten-Mualem model, the residual water contents θr were 0.0159, 0.0181, 0.0182, 0.0328, 0.0312, 0.0723, 0.0864 in the columns initially saturated by deionized water, 3 g/L, 15 g/L, 50 g/L, 100 g/L and 200 g/L, respectively. The van Genuchten-Mualem model, Fredlund-Xing model, Gardern model, Mckee-Bumb model and Brooks-Corey model were fitted by MATLAB with the experiments data, and the fitted coefficients were compared. The Fredlund-Xing model has the best fitting coefficients and the calculated value was consistent with the observed data.

An evaluation of supervised classifiers for indirectly detecting salt-affected areas at irrigation scheme level

NASA Astrophysics Data System (ADS)

Muller, Sybrand Jacobus; van Niekerk, Adriaan

2016-07-01

Soil salinity often leads to reduced crop yield and quality and can render soils barren. Irrigated areas are particularly at risk due to intensive cultivation and secondary salinization caused by waterlogging. Regular monitoring of salt accumulation in irrigation schemes is needed to keep its negative effects under control. The dynamic spatial and temporal characteristics of remote sensing can provide a cost-effective solution for monitoring salt accumulation at irrigation scheme level. This study evaluated a range of pan-fused SPOT-5 derived features (spectral bands, vegetation indices, image textures and image transformations) for classifying salt-affected areas in two distinctly different irrigation schemes in South Africa, namely Vaalharts and Breede River. The relationship between the input features and electro conductivity measurements were investigated using regression modelling (stepwise linear regression, partial least squares regression, curve fit regression modelling) and supervised classification (maximum likelihood, nearest neighbour, decision tree analysis, support vector machine and random forests). Classification and regression trees and random forest were used to select the most important features for differentiating salt-affected and unaffected areas. The results showed that the regression analyses produced weak models (<0.4 R squared). Better results were achieved using the supervised classifiers, but the algorithms tend to over-estimate salt-affected areas. A key finding was that none of the feature sets or classification algorithms stood out as being superior for monitoring salt accumulation at irrigation scheme level. This was attributed to the large variations in the spectral responses of different crops types at different growing stages, coupled with their individual tolerances to saline conditions.

Impacts of road salts on leaching behavior of lead contaminated soil.

PubMed

Wu, Jingjing; Kim, Hwidong

2017-02-15

Research was conducted to explore the effects of road salts on lead leaching from lead contaminated soil samples that were collected in an old residence area in Erie, PA. The synthetic precipitate leaching procedure (SPLP) test was employed to evaluate lead leaching from one of the lead contaminated soils in the presence of various levels of road salts (5%, 10%, 20%, 30% and 40%). The results of the leaching test showed that lead leaching dramatically increased as the road salt content increased as a result of the formation of lead-chloride complexes, but different lead leaching patterns were observed in the presence of NaCl- and CaCl 2 -based road salts at a high content of road salts (>20%). Additional leaching tests that include 30% road salts and different soil samples showed a variety of leaching patterns by soil samples. The sequential extraction of each soil sample showed that a high fraction of organic matter bound lead was associated with lead contamination. The higher the fraction of organic matter bound lead contained in soil, the greater the effects of calcium on reducing lead leaching, observations showed. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative Toxicities of Salts on Microbial Processes in Soil

PubMed Central

Maheshwari, Arpita; Bengtson, Per; Rousk, Johannes

2016-01-01

Soil salinization is a growing threat to global agriculture and carbon sequestration, but to date it remains unclear how microbial processes will respond. We studied the acute response to salt exposure of a range of anabolic and catabolic microbial processes, including bacterial (leucine incorporation) and fungal (acetate incorporation into ergosterol) growth rates, respiration, and gross N mineralization and nitrification rates. To distinguish effects of specific ions from those of overall ionic strength, we compared the addition of four salts frequently associated with soil salinization (NaCl, KCl, Na2SO4, and K2SO4) to a nonsaline soil. To compare the tolerance of different microbial processes to salt and to interrelate the toxicity of different salts, concentration-response relationships were established. Growth-based measurements revealed that fungi were more resistant to salt exposure than bacteria. Effects by salt on C and N mineralization were indistinguishable, and in contrast to previous studies, nitrification was not found to be more sensitive to salt exposure than other microbial processes. The ion-specific toxicity of certain salts could be observed only for respiration, which was less inhibited by salts containing SO42− than Cl− salts, in contrast to the microbial growth assessments. This suggested that the inhibition of microbial growth was explained solely by total ionic strength, while ion-specific toxicity also should be considered for effects on microbial decomposition. This difference resulted in an apparent reduction of microbial growth efficiency in response to exposure to SO42− salts but not to Cl− salts; no evidence was found to distinguish K+ and Na+ salts. PMID:26801570

Biotoxicity of Mars Analog Soils: Microbial, Dispersal into Desiccated Soils Versus Emplacement in Salt or Ice Inclusions Fluids

NASA Technical Reports Server (NTRS)

Schuerger, A. C.; Ming, Doutlas W.; Golden, D. C.

2010-01-01

Recent evidence from the Opportunity and Spirit rovers and the Mars Express mission suggests that the soils on Mars might be very high in biotoxic materials including sulfate salts, chlorides, and acidifying agents. Yet, very little is known about how the chemistries of Mars soils might affect the survival and growth of terrestrial microorganisms. The primary objectives of the research included: (1) prepare and characterize Mars analog soils amended with potential biotoxic levels of sulfates, chlorides, and acidifying minerals; and (2) use the simulants to conduct a series of toxicology assays to determine if terrestrial microorganisms from spacecraft can survive direct exposure to the biotoxic soils.

[Strengthening Effects of Sodium Salts on Washing Kerosene Contaminated Soil with Surfactants].

PubMed

Huang, Zhao-lu; Chen, Quan-yuan; Zhou, Juan; Xie, Mo-han

2015-05-01

The impact of sodium salt on kerosene contaminated soil washing with surfactants was investigated. The results indicated that sodium silicate greatly enhanced the washing efficiency of SDS. Sodium tartrate can largely enhance the washing efficiency of SDBS and Brij35. Sodium salts can enhance the washing efficiency on kerosene contaminated with TX-100. No significant differences were observed between different sodium salts. Sodium salt of humic acid and sodium silicate had similar enhancement on kerosene contaminated soil washing with saponin. Sodium humate can be a better choice since its application can also improve soil quality. The enhancement of sodium silicate on kerosene contaminated soil washing with Tw-80 increased with the increase of Tw-80 dosage. However, the impact of sodium chloride and sodium tartrate was opposite to sodium silicate. Sodium salts can reduce surface tension and critical micelle concentration of ionic surfactants to enhance the washing. Sodium salts can also reduce re-adsorption of oil to soil with nonionic surfactants to enhance the washing. Kerosene contamination can increase the contact angle of soil, which indicated the increase of hydrophilicity of soil. Washing with surfactants can reduce the hydrophilicitiy of soil according to contact angle measurement, which indicated that kerosene contaminated soil remediation with surfactant can also benefit nutrient and water transportation in the contaminated soil.

Carbon stocks in mangroves, salt marshes, and salt barrens in Tampa Bay, Florida, USA: Vegetative and soil characteristics.

NASA Astrophysics Data System (ADS)

Moyer, R. P.; Radabaugh, K.; Chappel, A. R.; Powell, C.; Bociu, I.; Smoak, J. M.

2017-12-01

When compared to other terrestrial environments, coastal "blue carbon" habitats such as salt marshes and mangrove forests sequester disproportionately large amounts of carbon as standing plant biomass and sedimentary peat deposits. This study quantified total carbon stocks in vegetation and soil of 17 salt marshes, salt barrens, and mangrove forests in Tampa Bay, Florida, USA. The sites included natural, restored, and created wetlands of varying ages and degrees of anthropogenic impacts. The average vegetative carbon stock in mangrove forests was 60.1 ± 2.7 Mg ha-1. Mangrove forests frequently consisted of a few large Avicennia germinans trees with smaller, abundant Rhizophora mangle and/or Laguncularia racemosa trees. The average vegetative carbon stock was 11.8 ± 3.7 Mg ha-1 for salt marshes and 2.0 ± 1.2 Mg ha-1 for salt barrens. Vegetative carbon did not significantly differ between natural and newly created salt marsh habitats, indicating that mature restored wetlands can be included with natural wetlands for the calculation of vegetative carbon in coastal blue carbon assessments. Peat deposits were generally less than 50 cm thick and organic content rapidly decreased with depth in all habitats. Soil in this study was analyzed in 1 cm intervals; the accuracy of subsampling or binning soil into depth intervals of 2-5 cm was also assessed. In most cases, carbon stock values obtained from these larger sampling intervals were not statistically different from values obtained from sampling at 1 cm intervals. In the first 15 cm, soil in mangrove forests contained an average of 15.1% organic carbon by weight, salt marshes contained 6.5%, and salt barrens contained 0.8%. Total carbon stock in mangroves was 187.1±17.3 Mg ha-1, with 68% of that carbon stored in soil. Salt marshes contained an average of 65.2±25.3 Mg ha-1 (82% soil carbon) and salt barrens had carbon stocks of 21.4±7.4 Mg ha-1 (89% soil carbon). These values were much lower than global averages for

Salt Attack on Rocks and Expansion of Soils on Mars

NASA Astrophysics Data System (ADS)

Vaniman, D. T.; Bish, D. L.; Chipera, S. J.; Carey, J. W.

2004-12-01

Salt-rich sediments observed by the MER rover Opportunity at Meridiani Planum show that brines have been present on Mars in the past, but a role for groundwater in widespread rock weathering and soil formation is uncertain. Experiments by several groups suggest instead the action of acid fog over long time spans, with episodic input of volcanic gases, as a more significant agent of Mars weathering. Salt minerals formed in these acid weathering experiments consistently include gypsum and alunogen, with epsomite or hexahydrite forming where olivine provides a source of Mg. Analogous to the martian acid fog scenario are terrestrial acid rain or acid fog attacks on building and monument stone by chemical action and mechanical wedging through growth of gypsum, anhydrite, epsomite, hexahydrite, kieserite, and other sulfate minerals. Physical effects can be aggressive, operating by both primary salt growth and hydration of anhydrous or less-hydrous primary salts. In contrast, soils evolve to states where chemical attack is lessened and salt mineral growth leads to expansion with cementation; in this situation the process becomes constructive rather than destructive. We have made synthetic salt-cemented soils (duricrusts) from clays, zeolites, palagonites and other media mixed with ultrapure Mg-sulfate solutions. Although near-neutral in pH, these solutions still exchange or leach Ca from the solids to form cements containing gypsum as well as hexahydrite. At low total P (1 torr) and low RH (<1%) hexahydrite becomes amorphous but gypsum does not. If allowed to rehydrate from vapor at higher RH, the Mg-sulfate component of the duricrust expands by formation of a complex mixture of Mg-sulfate phases with various hydration states. The expanded form is retained even if the duricrust is again dehydrated, suggesting that soil porosity thus formed is difficult to destroy. These processes can be considered in the context of Viking, Pathfinder, and MER evidence for differing salt

Plant growth-promoting bacteria facilitate the growth of barley and oats in salt-impacted soil: implications for phytoremediation of saline soils.

PubMed

Chang, Pearl; Gerhardt, Karen E; Huang, Xiao-Dong; Yu, Xiao-Ming; Glick, Bernard R; Gerwing, Perry D; Greenberg, Bruce M

2014-01-01

Plant growth-promoting bacteria (PGPB) strains that contain the enzyme 1-amino-cyclopropane-1-carboxylate (ACC) deaminase can lower stress ethylene levels and improve plant growth. In this study, ACC deaminase-producing bacteria were isolated from a ) salt-impacted ( 50 dS/m) farm field, and their ability to promote plant growth of barley 1): and oats in saline soil was investigated in pouch assays (1% NaCI), greenhouse trials (9.4 dS/m), and field trials (6-24 dS/m). A mix of previously isolated PGPB strains UW3 (Pseudomonas sp.) and UW4 (P. sp.) was also tested for comparison. Rhizobacterial isolate CMH3 (P. corrugata) and UW3+UW4 partially alleviated plant salt stress in growth pouch assays. In greenhouse trials, CMH3 enhanced root biomass of barley and oats by 200% and 50%, respectively. UW3+UW4, CMH3 and isolate CMH2 also enhanced barley and oat shoot growth by 100%-150%. In field tests, shoot biomass of oats tripled when treated with UW3+UW4 and doubled with CHM3 compared with that of untreated plants. PGPB treatment did not affect salt uptake on a per mass basis; higher plant biomass led to greater salt uptake, resulting in decreased soil salinity. This study demonstrates a method for improving plant growth in marginal saline soils. Associated implications for salt

Investigation of indigenous water, salt and soil for solar ponds

NASA Astrophysics Data System (ADS)

Marsh, H. E.

The existence of salt-gradient solar ponds in nature is a strong indication that the successful exploitation of this phenomenon must account adequately for the influences of the local setting. Sun, weather and other general factors are treated elsewhere. This paper deals with water, salt, and soil. A general methodology for evaluating and, where feasible, adjusting the effects of these elements is under development. Eight essential solar pond characteristics have been identified, along with a variety of their dependencies upon properties of water, salt and soil. The comprehensive methodology, when fully developed, will include laboratory investigation in such diverse areas as brine physical chemistry, light transmission, water treatment, brine-soil interactions, sealants, and others. With the Salton Sea solar pond investigation as an example, some methods under development will be described.

Investigation of indigenous water, salt and soil for solar ponds

NASA Technical Reports Server (NTRS)

Marsh, H. E.

1983-01-01

The existence of salt-gradient solar ponds in nature is a strong indication that the successful exploitation of this phenomenon must account adequately for the influences of the local setting. Sun, weather and other general factors are treated elsewhere. This paper deals with water, salt, and soil. A general methodology for evaluating and, where feasible, adjusting the effects of these elements is under development. Eight essential solar pond characteristics have been identified, along with a variety of their dependencies upon properties of water, salt and soil. The comprehensive methodology, when fully developed, will include laboratory investigation in such diverse areas as brine physical chemistry, light transmission, water treatment, brine-soil interactions, sealants, and others. With the Salton Sea solar pond investigation as an example, some methods under development will be described.

[Compensation effect of cotton growth and development after soil salt content reduction at bud stage].

PubMed

Guo, Wen-Qi; Zhang, Pei-Tong; Li, Chun-Hong; Yin, Jian-Mei; Han, Xiao-Yong

2014-01-01

To elucidate the dynamic characteristics of cotton growth and development after soil salt content reduction (SD) at bud stage and its effect on yield formation, a pot experiment was conducted in which soil salt content was declined from 5 per thousand level to 2 per thousand level at cotton bud stage. The results showed that the plant height, biomass, total fruit branch and fruit node number, boll number, boll mass of cotton plants increased after soil salt content reduction at bud stage. The distribution proportions of biomass in root and boll decreased after soil salt content reduction, however, the distribution proportions of biomass in leaf, main stem and fruit branch were on the rise. The growth rate of cotton plant increased after soil salt content reduction. Plant dry matter accumulation rate of SD cotton exceeded CK cotton at 22 days after soil salt content reduction. The response of different organs of cotton plant were different to soil salt content reduction, the plant height was the earliest, followed by the fruit branch and fruit node formation, and the bud and boll were the latest, which indicated that the compensation effect of cotton growth and development after soil salt content reduction at bud stage firstly appeared on the formation and growth of new leaf, fruit branch and fruit node, and on this basis, gradually brought out yield compensation.

[Effects of the grain size and thickness of dust deposits on soil water and salt movement in the hinterland of the Taklimakan Desert].

PubMed

Sun, Yan-Wei; Li, Sheng-Yu; Xu, Xin-Wen; Zhang, Jian-Guo; Li, Ying

2009-08-01

By using mcirolysimeter, a laboratory simulation experiment was conducted to study the effects of the grain size and thickness of dust deposits on the soil water evaporation and salt movement in the hinterland of the Taklimakan Desert. Under the same initial soil water content and deposition thickness condition, finer-textured (<0.063 mm) deposits promoted soil water evaporation, deeper soil desiccation, and surface soil salt accumulation, while coarse-textured (0.063-2 mm) deposits inhibited soil water evaporation and decreased deeper soil water loss and surface soil salt accumulation. The inhibition effect of the grain size of dust deposits on soil water evaporation had an inflection point at the grain size 0.20 mm, i. e., increased with increasing grain size when the grain size was 0.063-0.20 mm but decreased with increasing grain size when the grain size was > 0.20 mm. With the increasing thickness of dust deposits, its inhibition effect on soil water evaporation increased, and there existed a logarithmic relationship between the dust deposits thickness and water evaporation. Surface soil salt accumulation had a negative correlation with dust deposits thickness. In sum, the dust deposits in study area could affect the stability of arid desert ecosystem.

Subsurface Salts in Antarctic Dry Valley Soils

NASA Technical Reports Server (NTRS)

Englert, P.; Bishop, J. L.; Gibson, E. K.; Koeberl, C.

2013-01-01

The distribution of water-soluble ions, major and minor elements, and other parameters were examined to determine the extent and effects of chemical weathering on cold desert soils. Patterns at the study sites support theories of multiple salt forming processes, including marine aerosols and chemical weathering of mafic minerals. Periodic solar-mediated ionization of atmospheric nitrogen might also produce high nitrate concentrations found in older sediments. Chemical weathering, however, was the major contributor of salts in Antarctic Dry Valleys. The Antarctic Dry Valleys represent a unique analog for Mars, as they are extremely cold and dry desert environments. Similarities in the climate, surface geology, and chemical properties of the Dry Valleys to that of Mars imply the possible presence of these soil formation mechanisms on Mars, other planets and icy satellites.

Biomass production in agroforestry and forestry systems on salt-affected soils in South Asia: exploration of the GHG balance and economic performance of three case studies.

PubMed

Wicke, Birka; Smeets, Edward M W; Akanda, Razzaque; Stille, Leon; Singh, Ranjay K; Awan, Abdul Rasul; Mahmood, Khalid; Faaij, Andre P C

2013-09-30

This study explores the greenhouse gas balance and the economic performance (i.e. net present value (NPV) and production costs) of agroforestry and forestry systems on salt-affected soils (biosaline (agro)forestry) based on three case studies in South Asia. The economic impact of trading carbon credits generated by biosaline (agro)forestry is also assessed as a potential additional source of income. The greenhouse gas balance shows carbon sequestration over the plantation lifetime of 24 Mg CO2-eq. ha(-1) in a rice-Eucalyptus camaldulensis agroforestry system on moderately saline soils in coastal Bangladesh (case study 1), 6 Mg CO2-eq. ha(-1) in the rice-wheat- Eucalyptus tereticornis agroforestry system on sodic/saline-sodic soils in Haryana state, India (case study 2), and 96 Mg CO2-eq. ha(-1) in the compact tree (Acacia nilotica) plantation on saline-sodic soils in Punjab province of Pakistan. The NPV at a discount rate of 10% is 1.1 k€ ha(-1) for case study 1, 4.8 k€ ha(-1) for case study 2, and 2.8 k€ ha(-1) for case study 3. Carbon sequestration translates into economic values that increase the NPV by 1-12% in case study 1, 0.1-1% in case study 2, and 2-24% in case study 3 depending on the carbon credit price (1-15 € Mg(-1) CO2-eq.). The analysis of the three cases indicates that the economic performance strongly depends on the type and severity of salt-affectedness (which affect the type and setup of the agroforestry system, the tree species and the biomass yield), markets for wood products, possibility of trading carbon credits, and discount rate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Jerusalem artichoke decreased salt content and increased diversity of bacterial communities in the rhizosphere soil in the coastal saline zone

NASA Astrophysics Data System (ADS)

Shao, Tianyun; Li, Niu; Cheng, Yongwen; Long, Xiaohua; Shao, Hongbo; Zed, Rengel

2017-04-01

Soil salinity is one of the main environmental constraints that restrict plant growth and agricultural productivity; however, utilization of salt-affected land can bring substantial benefits. This study used an in-situ remediation method by planting Jerusalem artichoke in naturally occurring saline alkali soils with different salinity (high salinity (H, >4.0 g•salt kg-1 soil), moderate salinity (M, 2.0-4.0 g•salt kg-1 soil) and low salinity (L, 1.0-2.0 g•salt kg-1 soil) in the coastal saline zone in southeast China in comparison with the respective controls without Jerusalem artichoke planting (undisturbed soil). Soil pH and salinity increased sequentially from the rhizosphere to the bulk soil and the unplanted controls. The activity of neutral phosphatase and invertase decreased in the order L > M > H, whereas that of catalase was reverse. The minimum content of calcite, muscovite and quartz, and maximum content of chlorite and albite, were found in the control soils. Planting of Jerusalem artichoke enhanced bacterial microflora in saline alkali soil. Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes were the dominant phyla in all samples, accounting for more than 80% of the reads. The number of Operational Taxonomic Units (OTU) in the rhizosphere soil was, respectively, 1.27, 1.02 and 1.25 times higher compared with the bulk soil, suggesting that Jerusalem artichoke played a significant role in increasing abundance and diversity of soil microbial populations. The study showed that Jerusalem artichoke could be used to improve saline alkali soil by enriching bacterial communities, enhancing the activity of phosphatase and invertase, and decreasing soil salinity.

[Effects of spent mushroom compost on greenhouse cabbage growth under soil salt stress].

PubMed

Wang, Qiu-Ling; Wu, Liang-Huan; Dong, Lan-Xue; Chen, Zai-Ming; Wang, Zhong-Qiang

2011-05-01

A pot experiment was conducted to study the effect of spent mushroom compost (SMC) in alleviating greenhouse soil secondary salinization and cabbage salt stress. With the amendment of SMC, the salinized soil after 60 day cabbage cultivation had a pH value close to 7.0, its organic matter and available phosphorous contents increased significantly, and the increment of total water-soluble salt content reduced, compared with the control. When the amendment amount of SMC was 10 g x kg(-1), the increment of soil water soluble salt content was the least, suggesting that appropriate amendment with SMC could reduce the salt accumulation in greenhouse soil. Amendment with SMC increased the cabbage seed germination rate, plant height, plant fresh mass, chlorophyll SPAD value, and vitamin C content, and decreased the proline content significantly. All the results indicated that SMC could improve the growth environment of greenhouse cabbage, and effectively alleviate the detrimental effect of salt stress.

Zooming in and out: Scale dependence of extrinsic and intrinsic factors affecting salt marsh erosion

NASA Astrophysics Data System (ADS)

Wang, Heng; van der Wal, Daphne; Li, Xiangyu; van Belzen, Jim; Herman, Peter M. J.; Hu, Zhan; Ge, Zhenming; Zhang, Liquan; Bouma, Tjeerd J.

2017-07-01

Salt marshes are valuable ecosystems that provide important ecosystem services. Given the global scale of marsh loss due to climate change and coastal squeeze, there is a pressing need to identify the critical extrinsic (wind exposure and foreshore morphology) and intrinsic factors (soil and vegetation properties) affecting the erosion of salt marsh edges. In this study, we quantified rates of cliff lateral retreat (i.e., the eroding edge of a salt marsh plateau) using a time series of aerial photographs taken over four salt marsh sites in the Westerschelde estuary, the Netherlands. In addition, we experimentally quantified the erodibility of sediment cores collected from the marsh edge of these four marshes using wave tanks. Our results revealed the following: (i) at the large scale, wind exposure and the presence of pioneer vegetation in front of the cliff were the key factors governing cliff retreat rates; (ii) at the intermediate scale, foreshore morphology was partially related to cliff retreat; (iii) at the local scale, the erodibility of the sediment itself at the marsh edge played a large role in determining the cliff retreat rate; and (iv) at the mesocosm scale, cliff erodibility was determined by soil properties and belowground root biomass. Thus, both extrinsic and intrinsic factors determined the fate of the salt marsh but at different scales. Our study highlights the importance of understanding the scale dependence of the factors driving the evolution of salt marsh landscapes.

Enhancement of surfactant efficacy during the cleanup of engine oil contaminated soil using salt and multi-walled carbon nanotubes.

PubMed

Bonal, Niteesh Singh; Paramkusam, Bala Ramudu; Basudhar, Prabir Kumar

2018-06-05

The study aims to enhance the efficacy of surfactants using salt and multi-walled carbon nanotubes (MWCNT) for washing used engine oil (UEO) contaminated soil and compare the geotechnical properties of contaminated soil before and after washing (batch washing and soil washing). From batch washing of the contaminated soil the efficacy of the cleaning process is established. Contamination of soil with hydrocarbons present in UEO significantly affects its' engineering properties manifesting in no plasticity and low specific gravity; the corresponding optimum moisture content value is 6.42% while maximum dry density is 1.770 g/cc, which are considerably lower than those of the uncontaminated soil. The result also showed decrease in the values of cohesion intercept and increase in the friction angle values. The adopted soil washing technique resulted increase in specific gravity from 1.85 to 2.13 and cohesion from 0.443 to 1.04 kg/cm 2 and substantial decrease in the friction angle from 31.16° to 17.14° when washed with most efficient combination of SDS surfactant along with sodium meta-silicate (salt) and MWCNT. Effectiveness of the washing of contaminated soil by batch processing and soil washing techniques has been established qualitatively. The efficiency of surfactant treatment has been observed to be increased significantly by the addition of salt and MWCNT. Copyright © 2018 Elsevier B.V. All rights reserved.

[Simulation of effects of soil properties and plants on soil water-salt movement with reclaimed water irrigation by ENVIRO-GRO model].

PubMed

Lü, Si-Dan; Chen, Wei-Ping; Wang, Mei-E

2012-12-01

In order to promote safe irrigation with reclaimed water and prevent soil salinisation, the dynamic transport of salts in urban soils of Beijing under irrigation of reclaimed water was simulated by ENVIRO-GRO model in this study. The accumulation trends and profile distribution of soil salinity were predicted. Simultaneously, the effects of different soil properties and plants on soil water-salt movement and salt accumulation were investigated. Results indicated that soil salinity in the profiles reached uniform equilibrium conditions by repeated simulation, with different initial soil salinity. Under the conditions of loam and clay loam soil, salinity in the profiles increased over time until reaching equilibrium conditions, while under the condition of sandy loam soil, salinity in the profiles decreased over time until reaching equilibrium conditions. The saturated soil salinity (EC(e)) under equilibrium conditions followed an order of sandy loam < loam < clay loam. Salt accumulations in Japan euonymus and Chinese pine were less than that in Blue grass. The temporal and spatial distributions of soil salinity were also different in these three types of plants. In addition, the growth of the plants was not influenced by soil salinity (except clay loam), but mild soil salinization occurred under all conditions (except sandy loam).

Properties of hydrocarbon- and salt-contaminated flare pit soils in northeastern British Columbia (Canada).

PubMed

Arocena, J M; Rutherford, P M

2005-07-01

Many contaminated sites in Canada are associated with flare pits generated during past petroleum extraction operations. Flare pits are located adjacent to well sites, compressor stations and batteries and are often subjected to the disposal of wastes from the flaring of gas, liquid hydrocarbons and brine water. This study was conducted to evaluate the physical, chemical, electrical and mineral properties of three flare pit soils as compared to adjacent control soils. Results showed that particle size distribution, pH, total N, cation exchange capacity, exchangeable Mg(2+), and sodium adsorption ratio were similar in soils from flare pits and control sites. Total C, exchangeable Ca(2+), K(+) and Na(+), soluble Ca(2+), Mg(2+), K(+) and Na(+) and electrical conductivity were higher in flare pit soils compared to control soils. X-ray diffraction and scanning electron microscopic analyses showed the presence of gypsum [CaSO(4).2H(2)O], dolomite [CaMg(CO(3))(2)], pyrite [FeS(2)], jarosite [KFe(3)(OH)(6)(SO(4))(2)], magnesium sulphate, oxides of copper and iron+copper in salt efflorescence observed in flare pit soils. Soils from both flare pits and control sites contained mica, kaolonite and 2:1 expanding clays. The salt-rich materials altered the ionic equilibria in the flare pit soils; K(Mg-Ca) selectivity coefficients in control soils were higher compared to contaminated soils. The properties of soils (e.g., high electrical conductivity) affected by inputs associated with oil and gas operations might render flare pit soils less conducive to the establishment and growth of common agricultural crops and forest trees.

De-icing salt contamination reduces urban tree performance in structural soil cells.

PubMed

Ordóñez-Barona, Camilo; Sabetski, Vadim; Millward, Andrew A; Steenberg, James

2018-03-01

Salts used for de-icing roads and sidewalks in northern climates can have a significant impact on water quality and vegetation. Sub-surface engineering systems, such as structural soil cells, can regulate water runoff and pollutants, and provide the necessary soil volume and irrigation to grow trees. However, the ability of such systems to manage de-icing salt contamination, and the impact of this contamination on the trees growing in them, have not been evaluated. We report on an field investigation of de-icing salt contamination in structural cells in two street-revitalization projects in Toronto, Canada, and the impact of this contamination on tree performance. We analyzed soil chemistry and collected tree attributes; these data were examined together to understand the effect of salinity on tree mortality rates and foliar condition. Data collected from continuous soil salinity loggers from April to June for one of the two sites were used to determine whether there was a long-term accumulation of salts in the soils. Results for both sites indicate that both sites displayed high salinity and alkalinity, with levels elevated beyond those suggested before those reported to cause negative tree effects. For one site, trees that were alive and trees that had a better foliar condition had significantly lower levels of soil salinity and alkalinity than other trees. High salinity and alkalinity in the soil were also associated with lower nutrient levels for both sites. Although tests for salinity accumulation in the soils of one site were negative, a longer monitoring of the soil conditions within the soil cells is warranted. Despite structural cells being increasingly utilized for their dual role in storm-water management and tree establishment, there may be a considerable trade-off between storm-water management and urban-forest function in northern climates where de-icing salt application continues to be commonplace. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Occurrence, Sources and Spatial Characteristics of Soil Salt and Assessment of Soil Salinization Risk in Yanqi Basin, Northwest China

PubMed Central

Zhaoyong, Zhang; Abuduwaili, Jilili; Yimit, Hamid

2014-01-01

In order to evaluate the soil salinization risk of the oases in arid land of northwest China, we chose a typical oasis-the Yanqi basin as the research area. Then, we collected soil samples from the area and made comprehensive assessment for soil salinization risk in this area. The result showed that: (1) In all soil samples, high variation was found for the amount of Ca2+ and K+, while the other soil salt properties had moderate levels of variation. (2) The land use types and the soil parent material had a significant influence on the amount of salt ions within the soil. (3) Principle component (PC) analysis determined that all the salt ion values, potential of hydrogen (pHs) and ECs fell into four PCs. Among them, PC1 (C1-, Na+, SO4 2-, EC, and pH) and PC2 (Ca2+, K+, Mg2+and total amount of salts) are considered to be mainly influenced by artificial sources, while PC3 and PC4 (CO3 - and HCO3 2-) are mainly influenced by natural sources. (4) From a geo-statistical point of view, it was ascertained that the pH and soil salt ions, such as Ca2+, Mg2+ and HCO3 -, had a strong spatial dependency. Meanwhile, Na+ and Cl- had only a weak spatial dependency in the soil. (5) Soil salinization indicators suggested that the entire area had a low risk of soil salinization, where the risk was mainly due to anthropogenic activities and climate variation. This study can be considered an early warning of soil salinization and alkalization in the Yanqi basin. It can also provide a reference for environmental protection policies and rational utilization of land resources in the arid region of Xinjiang, northwest China, as well as for other oases of arid regions in the world. PMID:25211240

Nitrification and occurrence of salt-tolerant nitrifying bacteria in the Negev desert soils.

PubMed

Nejidat, Ali

2005-03-01

Ammonia oxidation potential, major ammonia oxidizers and occurrence of salt-tolerant nitrifying bacteria were studied in soil samples collected from diverse ecosystems along the northern Negev desert. Great diversity in ammonia oxidation potential was observed among the soil samples, and ammonia oxidizers were the rate-limiting step of nitrification. Denaturing gradient gel electrophoresis and partial 16S rRNA gene sequences indicate that members of the genus Nitrosospira are the major ammonia oxidizers in the natural desert soil samples. Upon enrichment with different salt concentrations, salt-tolerant nitrifying enrichments were established from several soil samples. In two enrichments, nitrification was not inhibited by 400 mM NaCl. Electrophoretic analysis and partial 16S rRNA gene sequences indicate that Nitrosomonas species were dominant in the 400 mM salt enrichment. The results point towards the potential of the desert ecosystem as a source of stress-tolerant nitrifying bacteria or other microorganisms with important properties.

Management of Atriplex nummularia Lindl. in a salt affected soil in a semi arid region of Brazil.

PubMed

de Souza, Edivan Rodrigues; Freire, Maria Betânia Galvão dos Santos; de Melo, Diego Vandeval Maranhão; Montenegro, Abelardo de Antônio Assunção

2014-01-01

This study aims to investigate the behavior of Atriplex nummularia under field conditions, including its growth, periodic cuttings, salt extraction, and soil chemical properties monitored for 16 months. Three treatments were evaluated: soil cultivated with Atriplex pruned at 6 and 12 months after transplanting (MAT); soil cultivated with plants that were harvested only at the end of the experiment (16 MAT); and a control (uncultivated soil) with four replications. Soil samplings were taken at 0, 6, 12, and 16 MAT. The samples were taken at depths of 0-20, 20-40, 40-60, and 60-80 cm. Biometric variables for growth were monitored monthly. The shoot was divided into leaves, thin stems (< or = 3 mm diameter), and thick stems (> 3 mm diameter) to determine its content of Ca, Mg, Na, K, and Cl. We concluded that pruning regime for Atriplex was efficient mainly because it stimulated regrowth of less lignified material (leaves and stems < or = 3 mm). We found that elements extracted by plant tissue can be quantified accurately, making them valuable indicators of the efficiency of the recovery process. The use of the Atriplex is recommended because the the possibility of revegetating areas inhospitable to most species used in conventional farming.

Designing viable cropping options for salt-affected lands

NASA Astrophysics Data System (ADS)

Shabala, Sergey; Meinke, Holger

2017-04-01

Salinity cost agricultural sector over 27Bln pa in lost opportunities and is an issue that crosses all spatial and temporal scales - from individual fields, farms, catchments, landscapes to national and global levels. Salinity manifests itself in many forms and often leads to further soil degradation such as erosion, nutrient and soil organic matter depletion, and a loss of (soil) biodiversity. Salinity may also cause major disturbance to ecosystems due to its impact on resources (e.g. pollution of aquifers). In extreme cases it can turn previously highly productive areas into wastelands. An increasing global population and unprecedented urban sprawls are now putting additional pressures on our soil and water resources, particularly in regions where urbanisation directly competes with agriculture for access to land and water. And although everyone agrees that avoiding soil salinity in the first instance would be the most effective way of combating it, reality is that the amount of saline land and water resources is rapidly increasing, and will continue to increase, especially in developing countries. Purposefully designing our cropping systems that can cope with various levels of salinity could be one answer to this increasing problem. In this work we review some of the key cropping options that can be deployed to either avoid, reduce or remediate salt-affected lands. We argue that for these measures to be most effective an ongoing science - policy - society dialogue is required to ensure that policy frameworks that govern land and water management are conducive to reducing salinity or even assist in restoring affected areas. We first consider several case studies highlighting the extent of the problem using ongoing salinity hotspots around the globe. We then look at halophytes as a possible biological tools to remediate already saline sols, and discuss prospects of mixed (halophytes and glycophytes) cropping solutions for various agricultural systems at different

Productivity of sodic soils can be enhanced through the use of salt tolerant rice varieties and proper agronomic practices.

PubMed

Singh, Y P; Mishra, V K; Singh, Sudhanshu; Sharma, D K; Singh, D; Singh, U S; Singh, R K; Haefele, S M; Ismail, A M

2016-04-01

Regaining the agricultural potential of sodic soils in the Indo-Gangetic plains necessitates the development of suitable salt tolerant rice varieties to provide an entry for other affordable agronomic and soil manipulation measures. Thus selection of high yielding rice varieties across a range of sodic soils is central. Evaluation of breeding lines through on-station and on-farm farmers' participatory varietal selection (FPVS) resulted in the identification of a short duration (110-115 days), high yielding and disease resistant salt-tolerant rice genotype 'CSR-89IR-8', which was later released as 'CSR43' in 2011. Several agronomic traits coupled with good grain quality and market value contributed to commercialization and quick adoption of this variety in the sodic areas of the Indo-Gangetic plains of eastern India. Management practices required for rice production in salt affected soils are evidently different from those in normal soils and practices for a short duration salt tolerant variety differ from those for medium to long duration varieties. Experiments were conducted at the Indian Council of Agricultural Research-Central Soil Salinity Research Institute (ICAR-CSSRI), Regional Research Station, Lucknow, Uttar Pradesh, India during 2011 and 2013 wet seasons, to test the hypothesis that combining matching management practices (Mmp) with an improved genotype would enhance productivity and profitability of rice in sodic soils. Mmp were developed on-station by optimizing existing best management practices (Bmp) recommended for the region to match the requirements of CSR43. The results revealed that transplanting 4 seedlings hill -1 at a spacing of 15 × 20 cm produced significantly higher yield over other treatments. The highest additional net gain was US$ 3.3 at 90 kg ha -1  N, and the lowest was US$ 0.4 at 150 kg ha -1  N. Above 150 kg ha -1 , the additional net gain became negative, indicating decreasing returns from additional N. Hence, 150�

The effect of vapor transport of acidic aerosols on salt speciation in Antarctic soils collected near the polar plateau

NASA Astrophysics Data System (ADS)

Graly, J. A.; Licht, K.; Kaplan, M. R.; Druschel, G.

2017-12-01

Vapor is the primary phase in which water is transported through soils where temperatures rarely, if ever, reach the melting point. In terrestrial settings, such as Antarctica, these cold, dry soils accumulate appreciable quantities of salts, primarily derived from atmospheric aerosols. Past studies have often analyzed the transport of salts to depth using solubility parameters, which assumes liquid water can percolate through porous media. We analyzed the distribution of salts in an Antarctic blue ice moraine, located near the polar plateau (84˚S, 163˚E). Here moraine soils are progressively older with distance from active ice, the oldest soils dating to several hundred ka. Changes in salt content were analyzed both with depth and with soil age. Of atmospheric salts analyzed, chloride and fluoride salts are fluxed to greatest depth, followed by nitrate salts. Sulfate and borate salts are both relatively immobile in the soil and are not detected below the top several cm. This distribution runs counter to the solubility of the salt species, with borate having high solubility and fluoride and nitrate both being relatively insoluble. Instead, the vapor pressures of the acids from which the salts form correspond very strongly with the relative abundance of the salts at depth. This suggests that percolation of liquid water plays a minimal role in moving salts to depth. Instead salts move to depth as vapors of acidic aerosols. With soil age, surface concentrations of the more mobile salts (nitrate, chloride, and fluoride) show logarithmic or power-law increases in concentrations, whereas boron and sulfate increase linearly. This is consistent with the former's progressive flux to depth. An exception to this pattern occurs in a few of the oldest soils, where substantially higher concentrations of the mobile salts are found in the top soils. This suggests that the direction of net vapor flux may reverse once sufficient salt concentration is developed at depth, though

Climate and soil salinity in the deserts of Central Asia

NASA Astrophysics Data System (ADS)

Pankova, E. I.; Konyushkova, M. V.

2013-07-01

A comparative analysis of climatic and soil salinity characteristics of the deserts of Central Asia, including deserts of the Turan Depression, the Gobi Desert, and deserts of the Dzungar and Tarim depressions was performed. The climatic characteristics—the degree of aridity, the degree of continentality, and the amount and regime of precipitation—are different in these deserts. No direct relationships between the areas occupied by the automorphic salt-affected soils and the aridity of the climate are observed in the studied regions. In the automorphic landscapes of Asian deserts, the degree and chemistry of the soil salinization and the distribution of salt-affected soils are controlled by the history of the particular territories rather than by their modern climatic conditions. The presence and properties of the salt-bearing rocks and the eolian migration of salts play the most significant role. The deficit of moisture in the modern climate favors the preservation of salt accumulations in places of their origin. The specific features of the climate, including the regime of precipitation, affect the redistribution of salts in the profiles of automorphic salt-affected soils. An increase in the degree of climatic continentality is accompanied by the decrease in the intensity of weathering and initial accumulation of salts. A different situation is observed in the soils of hydromorphic desert landscapes, in which the degree of salinity of the surface horizons and the area occupied by salt-affected soils are directly influenced by the modern climatic conditions.

[Simulation of effect of irrigation with reclaimed water on soil water-salt movement by ENVIRO-GRO model].

PubMed

Lü, Si-Dan; Chen, Wei-Ping; Wang, Mei-E

2012-12-01

As the conflict between water supply and demand, wastewater reuse has become an important measure, which can relieve the water shortage in Beijing. In order to promote safe irrigation with reclaimed water and prevent soil salinisation, the dynamic transport of salts in urban soils of Beijing, a city of water shortage, under irrigation of reclaimed water was simulated by ENVIRO-GRO model in this research. The accumulation trends of soil salinity were predicted. Simultaneously, it investigated the effects of different irrigation practices on soil water-salt movement and salt accumulation. Results indicated that annual averages of soil salinity (EC(e)) increased 29.5%, 97.2%, 197.8% respectively, with the higher irrigation, normal irrigation, and low irrigation under equilibrium conditions. Irrigation frequency had little effect on soil salt-water movement, and soil salt accumulation was in a downward trend with low frequency of irrigation. Under equilibrium conditions, annual averages of EC(e) increased 23.7%, 97.2%, 208.5% respectively, with irrigation water salinity (EC(w)) 0.6, 1.2, 2.4 dS x m(-1). Soil salinity increased slightly with EC(w) = 0.6 dS x m(-1), while soil salinization did not appear. Totally, the growth of Blue grass was not influenced by soil salinity under equilibrium conditions with the regular irrigation in Beijing, but mild soil salinization appeared.

Influences of Different Halophyte Vegetation on Soil Microbial Community at Temperate Salt Marsh.

PubMed

Chaudhary, Doongar R; Kim, Jinhyun; Kang, Hojeong

2018-04-01

Salt marshes are transitional zone between terrestrial and aquatic ecosystems, occupied mainly by halophytic vegetation which provides numerous ecological services to coastal ecosystem. Halophyte-associated microbial community plays an important role in the adaptation of plants to adverse condition and also affected habitat characteristics. To explore the relationship between halophytes and soil microbial community, we studied the soil enzyme activities, soil microbial community structure, and functional gene abundance in halophytes- (Carex scabrifolia, Phragmites australis, and Suaeda japonica) covered and un-vegetated (mud flat) soils at Suncheon Bay, South Korea. Higher concentrations of total, Gram-positive, Gram-negative, total bacterial, and actinomycetes PLFAs (phospholipid fatty acids) were observed in the soil underneath the halophytes compared with mud flat soil and were highest in Carex soil. Halophyte-covered soils had different microbial community composition due to higher abundance of Gram-negative bacteria than mud flat soil. Similar to PLFA concentrations, the increased activities of β-glucosidase, cellulase, phosphatase, and sulfatase enzymes were observed under halophyte soil compared to mud flat soil and Carex exhibited highest activities. The abundance of archaeal 16S rRNA, fungal ITS, and denitrifying genes (nirK, nirS, and nosZ) were not influenced by the halophytes. Abundance bacterial 16S rRNA and dissimilatory (bi)sulfite (dsrA) genes were highest in Carex-covered soil. The abundance of functional genes involved in methane cycle (mcrA and pmoA) was not affected by the halophytes. However, the ratios of mcrA/pmoA and mcrA/dsrA increased in halophyte-covered soils which indicate higher methanogenesis activities. The finding of the study also suggests that halophytes had increased the microbial and enzyme activities, and played a pivotal role in shaping microbial community structure.

Response of Soil Fungi Community Structure to Salt Vegetation Succession in the Yellow River Delta.

PubMed

Wang, Yan-Yun; Guo, Du-Fa

2016-10-01

High-throughput sequencing technology was used to reveal the composition and distribution of fungal community structure in the Yellow River Delta under bare land and four kinds of halophyte vegetation (saline seepweed, Angiospermae, Imperata and Apocynum venetum [A. venetum]). The results showed that the soil quality continuously improved with the succession of salt vegetation types. The soil fungi richness of mild-salt communities (Imperata and A. venetum) was relatively higher, with Shannon index values of 5.21 and 5.84, respectively. The soil fungi richness of severe-salt-tolerant communities (saline seepweed, Angiospermae) was relatively lower, with Shannon index values of 4.64 and 4.66, respectively. The UniFrac metric values ranged from 0.48 to 0.67 when the vegetation was in different succession stages. A total of 60,174 valid sequences were obtained for the five vegetation types, and they were classified into Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Mucoromycotina. Ascomycota had the greatest advantage among plant communities of Imperata and A. venetum, as indicated by relative abundances of 2.69 and 69.97 %, respectively. Basidiomycota had the greatest advantage among mild-salt communities of saline seepweed and Angiospermae, with relative abundances of 9.43 and 6.64 %, respectively. Soil physical and chemical properties were correlated with the distribution of the fungi, and Mucor was significantly correlated with soil moisture (r = 0.985; P < 0.01). Soil quality, salt vegetation and soil fungi were influenced by each other.

Iron clad wetlands: Soil iron-sulfur buffering determines coastal wetland response to salt water incursion

NASA Astrophysics Data System (ADS)

Schoepfer, Valerie A.; Bernhardt, Emily S.; Burgin, Amy J.

2014-12-01

Coastal freshwater wetland chemistry is rapidly changing due to increased frequency of salt water incursion, a consequence of global change. Seasonal salt water incursion introduces sulfate, which microbially reduces to sulfide. Sulfide binds with reduced iron, producing iron sulfide (FeS), recognizable in wetland soils by its characteristic black color. The objective of this study is to document iron and sulfate reduction rates, as well as product formation (acid volatile sulfide (AVS) and chromium reducible sulfide (CRS)) in a coastal freshwater wetland undergoing seasonal salt water incursion. Understanding iron and sulfur cycling, as well as their reduction products, allows us to calculate the degree of sulfidization (DOS), from which we can estimate how long soil iron will buffer against chemical effects of sea level rise. We show that soil chloride, a direct indicator of the degree of incursion, best predicted iron and sulfate reduction rates. Correlations between soil chloride and iron or sulfur reduction rates were strongest in the surface layer (0-3 cm), indicative of surface water incursion, rather than groundwater intrusion at our site. The interaction between soil moisture and extractable chloride was significantly related to increased AVS, whereas increased soil chloride was a stronger predictor of CRS. The current DOS in this coastal plains wetland is very low, resulting from high soil iron content and relatively small degree of salt water incursion. However, with time and continuous salt water exposure, iron will bind with incoming sulfur, creating FeS complexes, and DOS will increase.

The geostatistic-based spatial distribution variations of soil salts under long-term wastewater irrigation.

PubMed

Wu, Wenyong; Yin, Shiyang; Liu, Honglu; Niu, Yong; Bao, Zhe

2014-10-01

The purpose of this study was to determine and evaluate the spatial changes in soil salinity by using geostatistical methods. The study focused on the suburb area of Beijing, where urban development led to water shortage and accelerated wastewater reuse to farm irrigation for more than 30 years. The data were then processed by GIS using three different interpolation techniques of ordinary kriging (OK), disjunctive kriging (DK), and universal kriging (UK). The normality test and overall trend analysis were applied for each interpolation technique to select the best fitted model for soil parameters. Results showed that OK was suitable for soil sodium adsorption ratio (SAR) and Na(+) interpolation; UK was suitable for soil Cl(-) and pH; DK was suitable for soil Ca(2+). The nugget-to-sill ratio was applied to evaluate the effects of structural and stochastic factors. The maps showed that the areas of non-saline soil and slight salinity soil accounted for 6.39 and 93.61%, respectively. The spatial distribution and accumulation of soil salt were significantly affected by the irrigation probabilities and drainage situation under long-term wastewater irrigation.

Investigation of iodine concentration in salt, water and soil along the coast of Zhejiang, China*

PubMed Central

Lu, Ying-li; Wang, Ning-jian; Zhu, Lan; Wang, Guo-xing; Wu, Hui; Kuang, Lin; Zhu, Wen-ming

2005-01-01

Objective: We aim to describe the environment iodine concentration in salt, water and soil along Zhejiang Province coast in the China foreland. It will be helpful for us to judge whether this area is insufficient in iodine and universal iodized salt is necessary or not. Methods: We collected iodized salt samples, drinking water samples (tap water in the towns, and well water or spring water in the villages), water samples from different sources (ditches, lakes, rivers) and soil samples through random sampling in June, 2005. Salt, water and soil iodine was detected by arsenic-cerium redox method. Statistical analysis was expressed as mean±SEM by Windows SPSS 13.0. Results: (1) The iodine concentration in salt was 27.9±4.33 mg/kg (n=108). (2) Seventy-five water samples were collected. The water iodine value was 0.6~84.8 μg/L (mean of 11.66 μg/L). The watershed along the Qiantang River has significantly higher iodine content than the water in Lin’an in mountain area (P<0.01). The iodine content and mean iodine content of tap water, well or spring water and natural water sources were 4.30±2.43 μg/L (n=34), 23.59±27.74 μg/L (n=19) and 12.72±10.72 μg/L (n=22) respectively. This indicated that among environmental water sources, the ditch iodine content was the highest with river water iodine being the lowest (P<0.01). (3) Soil iodine value was 0.11~2.93 mg/kg (mean of 1.32 mg/kg). Though there was no statistical difference of soil iodine in different districts (P=0.131), soil iodine content correlated positively with water iodine content. Conclusion: Iodine concentration in salt accords with national policy of adding iodine in salt. Foreland has more iodine in water than mountain area. The data reflected that water and soil iodine in foreland area was not high, which suggests universal iodized salt should be necessary. Environment iodine has relatively close association with pollution. PMID:16358379

Biotoxicity of Mars Analog Soils: Microbial Dispersal into Desiccated Soils Versus Emplacement in Salt or Ice Inclusion Fluids

NASA Astrophysics Data System (ADS)

Schuerger, A. C.; Ming, D. W.; Golden, D. C.

2010-04-01

Six Mars analog soils were prepared to simulate a range of potentially biotoxic soils. Interactive effects of high-salt, desiccation, and low pressure were responsible for significant decreases in viable numbers of microbial species tested under martian conditions for 7 d.

Agroforestry-based management of salt-affected croplands in irrigated agricultural landscape in Uzbekistan

NASA Astrophysics Data System (ADS)

Khamzina, Asia; Kumar, Navneet; Heng, Lee

2017-04-01

In the lower Amu Darya River Basin, the decades of intensive irrigation led to elevated groundwater tables, resulting in ubiquitous soil salinization and adverse impact on crop production. Field-scale afforestation trials and farm-scale economic analyses in the Khorezm region have determined that afforestation can be an environmentally and financially attractive land-use option for degraded croplands because it combines a diversified agricultural production, carbon sequestration, an improved soil health and minimizes the use of irrigation water. We examined prospects for upscaling afforestation activity for regional land-use planning considering prevailing constraints in irrigated agriculture landscape. Assessment of salinity-induced cropland productivity decline using satellite imagery of multiple spatial and temporal resolution revealed that 18-38% of the marginally productive or abandoned cropland might be considered for conversion to agroforestry. Furthermore, a regional-scale water balance suggests that most of these marginal croplands are characterized by sufficient surface water supplies for irrigating the newly planted saplings, before they are able to rely on the groundwater alone. However, the 10-year monitoring of soil salt dynamics in the afforestation trials reveals increasing salinity levels due to the salt exclusion from the root water uptake by the trees. Further study focuses on enhancing long-term sustainability of afforestation as a management option for highly saline lands by examining salt tolerance of candidate species using 13C isotopic signature as the indicator of water and salt stress, salt leaching needs and implications for regional scale planning.

Salts affect the interaction of ZnO or CuO nanoparticles with wheat.

PubMed

Stewart, Jacob; Hansen, Trevor; McLean, Joan E; McManus, Paul; Das, Siddhartha; Britt, David W; Anderson, Anne J; Dimkpa, Christian O

2015-09-01

Exposure to nanoparticles (NPs) that release metals with potential phytotoxicity could pose problems in agriculture. The authors of the present study used growth in a model growth matrix, sand, to examine the influence of 5 mmol/kg of Na, K, or Ca (added as Cl salts) and root exudates on transformation and changes to the bioactivity of copper(II) oxide (CuO) and zinc oxide (ZnO) NPs on wheat. These salt levels are found in saline agricultural soils. After 14 d of seedling growth, particles with crystallinity typical of CuO or ZnO remained in the aqueous fraction from the sand; particles had negative surface charges that differed with NP type and salt, but salt did not alter particle agglomeration. Reduction in shoot and root elongation and lateral root induction by ZnO NPs were mitigated by all salts. However, whereas Na and K promoted Zn loading into shoots, Ca reduced loading, suggesting that competition with Zn ions for uptake occurred. With CuO NPs, plant growth and loading was modified equally by all salts, consistent with major interaction with the plant with CuO rather than Cu ions. Thus, for both NPs, loading into plant tissues was not solely dependent on ion solubility. These findings indicated that salts in agricultural soils could modify the phytotoxicity of NPs. © 2015 SETAC.

[Evolvement of soil quality in salt marshes and reclaimed farmlands in Yancheng coastal wetland].

PubMed

Mao, Zhi-Gang; Gu, Xiao-Hong; Liu, Jin-E; Ren, Li-Juan; Wang, Guo-Xiang

2010-08-01

Through vegetation investigation and soil analysis, this paper studied the evolvement of soil quality during natural vegetation succession and after farmland reclamation in the Yancheng coastal wetland of Jiangsu Province. Along with the process of vegetation succession, the soil physical, chemical, and biological properties in the wetland improved, which was manifested in the improvement of soil physical properties and the increase of soil nutrient contents, microbial biomass, and enzyme activities. Different vegetation type induced the differences in soil properties. Comparing with those in salt marshes, the soil salt content in reclaimed farmlands decreased to 0.01 - 0.04%, the soil microbial biomass and enzyme activities increased, and the soil quality improved obviously. The soil quality index (SQI) in the wetland was in the order of mudflat (0.194) < Suaeda salsa flat (0.233) < Imperata cylindrica flat (0.278) < Spartina alterniflora flat (0.446) < maize field (0.532) < cotton field (0.674) < soybean field (0.826), suggesting that positive vegetation succession would be an effective approach in improving soil quality.

Research on chemical characteristics of soil salt crusts with saline groundwater drip-irrigation in the Tarim Desert Highway Shelterbelt.

PubMed

Zhang, Jianguo; Xu, Xinwen; Lei, Jiaqiang; Li, Shengyu

2013-01-01

Soil salt crusts are special layers at soil surface which are widely distributed in the Trim Desert Highway Shelterbelt under drip-irrigation with high salinity groundwater. In order to reveal annual variation of their chemical characteristics, soil salt crusts in shelterbelt of different ages in hinterland of the Taklimakan Desert were sampled. SOM, total salt, inions and pH were analyzed. Following results were obtained. SOM of salt crusts increased with the shelterbelt ages, but increasing trend became lower gradually. Total salt, ions, and pH of salt crusts reduced gradually with the shelterbelt ages. Total salt of salt crusts in shelterbelt of different ages was much higher than shifting sandy land. Ions were higher than shifting sandy land, Cl(-), Na(+), and SO4 (2-) increased more obvious, then Mg(2+), K(+), Ca(2+) and HCO3 (-), CO3 (2-) was little and nearly had no change. pH was all alkaline, pH of salt crusts in shelterbelt of 11 years was even lower than shifting sandy land. We can include that the quality of shallow soil (0~30 cm) in the Trim Desert Highway Shelterbelt becomes better gradually.

Soil-geomorphology relationships and landscape evolution in a southwestern Atlantic tidal salt marsh in Patagonia, Argentina

NASA Astrophysics Data System (ADS)

Ríos, Ileana; Bouza, Pablo José; Bortolus, Alejandro; Alvarez, María del Pilar

2018-07-01

Salt marshes in Patagonia ecosystem are nowadays fully recognized by ecological, pollution and phytoremediation studies but a soil genesis and geomorphology approach is currently unknown. The aim of this study was to establish the soil-geomorphology relationship in Fracasso salt marsh and to determine the successional vegetation dynamics associated with the landscape evolution. This work was carried out in Fracasso salt marsh sited in Península Valdés, Argentina, where an integrated study on soil-geomorphology relationship and landscape evolution was performed along with sedimentological analysis and vegetation changes (C3 photosynthesis pathway vs. C4 photosynthesis pathway plants). This last was determined through the δ13C composition from soil organic matter (SOM). Soil descriptions and laboratory analysis of soil samples were performed. A marked relationship between the vegetation unit, the dominant landform and the type of associated soil was found. Limonium brasiliense (Lb) and Sarcocornia perennis (Sp), both C3 plants, are dominant in levees associated with tidal creeks, and soils were classified as Typic Fluvaquents, while Spartina alterniflora (Sa) soils were classified as Sodic Endoaquents and Sodic Psammaquents. Although no sulfidic materials were identified by incubation test, they were identified by hydrogen peroxide treatment in Sa soils, and now are considered potential acid sulfate soils (PASS). Sedimentological analysis from deepest sandy C horizons indicates a beach depositional environment. On the other hand, the δ13C stable isotope composition of SOM preserved into these buried soil acting as parent materials shows the dominance of C4 plants presumably belonging to Spartina species, suggesting a possible colonization and stabilization as the pioneer salt marsh.

[Monitoring of water and salt transport in silt and sandy soil during the leaching process].

PubMed

Fu, Teng-Fei; Jia, Yong-Gang; Guo, Lei; Liu, Xiao-Lei

2012-11-01

Water and salt transport in soil and its mechanism is the key point of the saline soil research. The dynamic rule of water and transport in soil during the leaching process is the theoretical basis of formation, flush, drainage and improvement of saline soil. In this study, a vertical infiltration experiment was conducted to monitor the variation in the resistivity of silt and sandy soil during the leaching process by the self-designed automatic monitoring device. The experimental results showed that the peaks in the resistivity of the two soils went down and faded away in the course of leaching. It took about 30 minutes for sandy soil to reach the water-salt balance, whereas the silt took about 70 minutes. With the increasing leaching times, the desalination depth remained basically the same, being 35 cm for sandy soil and 10 cm for the silt from the top to bottom of soil column. Therefore, 3 and 7 leaching processes were required respectively for the complete desalination of the soil column. The temporal and spatial resolution of this monitoring device can be adjusted according to the practical demand. This device can not only achieve the remote, in situ and dynamic monitoring data of water and salt transport, but also provide an effective method in monitoring, assessment and early warning of salinization.

Plant salt-tolerance mechanisms

DOE PAGES

Deinlein, Ulrich; Stephan, Aaron B.; Horie, Tomoaki; ...

2014-06-01

Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt-tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components can play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made towards engineering salt tolerance in crops, including marker-assisted selectionmore » and gene stacking techniques. We also identify key open questions that remain to be addressed in the future.« less

Stochastic Modeling of Soil Salinity

NASA Astrophysics Data System (ADS)

Suweis, Samir; Rinaldo, Andrea; van der Zee, Sjoerd E. A. T. M.; Maritan, Amos; Porporato, Amilcare

2010-05-01

Large areas of cultivated land worldwide are affected by soil salinity. Estimates report that 10% of arable land in over 100 countries, and nine million km2 are salt affected, especially in arid and semi-arid regions. High salinity causes both ion specific and osmotic stress effects, with important consequences for plant production and quality. Salt accumulation in the root zone may be due to natural factors (primary salinization) or due to irrigation (secondary salinization). Simple (e.g., vertically averaged over the soil depth) coupled soil moisture and salt balance equations have been used in the past. Despite their approximations, these models have the advantage of parsimony, thus allowing a direct analysis of the interplay of the main processes. They also provide the ideal starting point to include external, random hydro-climatic fluctuations in the analysis of long-term salinization trends. We propose a minimalist stochastic model of primary soil salinity, in which the rate of soil salinization is determined by the balance between dry and wet salt deposition and the intermittent leaching events caused by rainfall events. The long term probability density functions of salt mass and concentration are found by reducing the coupled soil moisture and salt mass balance equation to a stochastic differential equation driven by multiplicative Poisson noise. The novel analytical solutions provide insight on the interplay of the main soil, plant and climate parameters responsible for long-term soil salinization. In fact, soil salinity statistics are obtained as a function of climate, soil and vegetation parameters. These, in turn, can be combined with soil moisture statistics to obtain a full characterization of soil salt concentrations and the ensuing risk of primary salinization. In particular, the solutions show the existence of two quite distinct regimes, the first one where the mean salt mass remains nearly constant with increasing rainfall frequency, and the

Salt type and concentration affect the viscoelasticity of polyelectrolyte solutions

NASA Astrophysics Data System (ADS)

Turkoz, Emre; Perazzo, Antonio; Arnold, Craig B.; Stone, Howard A.

2018-05-01

The addition of small amounts of xanthan gum to water yields viscoelastic solutions. In this letter, we show that the viscoelasticity of aqueous xanthan gum solutions can be tuned by different types of salts. In particular, we find that the decrease in viscoelasticity not only depends, as is known, on the salt concentration, but also is affected by the counterion ionic radius and the valence of the salt.

Soil Salt Distribution and Tomato Response to Saline Water Irrigation under Straw Mulching

PubMed Central

Zhai, Yaming; Yang, Qian; Wu, Yunyu

2016-01-01

To investigate better saline water irrigation scheme for tomatoes that scheduling with the compromise among yield (Yt), quality, irrigation water use efficiency (IWUE) and soil salt residual, an experiment with three irrigation quotas and three salinities of irrigation water was conducted under straw mulching in northern China. The irrigation quota levels were 280 mm (W1), 320 mm (W2) and 360 mm (W3), and the salinity levels were 1.0 dS/m (F), 3.0 dS/m (S1) and 5.0 dS/m (S2). Compared to freshwater, saline water irrigations decreased the maximum leaf area index (LAIm) of tomatoes, and the LAIm presented a decline tendency with higher salinity and lower irrigation quota. The best overall quality of tomato was obtained by S2W1, with the comprehensive quality index of 3.61. A higher salinity and lower irrigation quota resulted in a decrease of individual fruit weight and an increase of the blossom-end rot incidence, finally led to a reduction in the tomato Yt and marketable yield (Ym). After one growth season of tomato, the mass fraction of soil salt in plough layer under S2W1 treatment was the highest, and which presented a decline trend with an increasing irrigation quota. Moreover, compared to W1, soil salts had a tendency to move to the deeper soil layer when using W2 and W3 irrigation quota. According to the calculation results of projection pursuit model, S1W3 was the optimal treatment that possessed the best comprehensive benefit (tomato overall quality, Yt, Ym, IWUE and soil salt residual), and was recommended as the saline water irrigation scheme for tomatoes in northern China. PMID:27806098

Soil Salt Distribution and Tomato Response to Saline Water Irrigation under Straw Mulching.

PubMed

Zhai, Yaming; Yang, Qian; Wu, Yunyu

2016-01-01

To investigate better saline water irrigation scheme for tomatoes that scheduling with the compromise among yield (Yt), quality, irrigation water use efficiency (IWUE) and soil salt residual, an experiment with three irrigation quotas and three salinities of irrigation water was conducted under straw mulching in northern China. The irrigation quota levels were 280 mm (W1), 320 mm (W2) and 360 mm (W3), and the salinity levels were 1.0 dS/m (F), 3.0 dS/m (S1) and 5.0 dS/m (S2). Compared to freshwater, saline water irrigations decreased the maximum leaf area index (LAIm) of tomatoes, and the LAIm presented a decline tendency with higher salinity and lower irrigation quota. The best overall quality of tomato was obtained by S2W1, with the comprehensive quality index of 3.61. A higher salinity and lower irrigation quota resulted in a decrease of individual fruit weight and an increase of the blossom-end rot incidence, finally led to a reduction in the tomato Yt and marketable yield (Ym). After one growth season of tomato, the mass fraction of soil salt in plough layer under S2W1 treatment was the highest, and which presented a decline trend with an increasing irrigation quota. Moreover, compared to W1, soil salts had a tendency to move to the deeper soil layer when using W2 and W3 irrigation quota. According to the calculation results of projection pursuit model, S1W3 was the optimal treatment that possessed the best comprehensive benefit (tomato overall quality, Yt, Ym, IWUE and soil salt residual), and was recommended as the saline water irrigation scheme for tomatoes in northern China.

The structure of salt marsh soil mesofauna food webs – The prevalence of disturbance

PubMed Central

Kiggen, Mirijam; Klarner, Bernhard; Maraun, Mark; Scheu, Stefan

2017-01-01

Mesofauna taxa fill key trophic positions in soil food webs, even in terrestrial–marine boundary habitats characterized by frequent natural disturbances. Salt marshes represent such boundary habitats, characterized by frequent inundations increasing from the terrestrial upper to the marine pioneer zone. Despite the high abundance of soil mesofauna in salt marshes and their important function by facilitating energy and carbon flows, the structure, trophic ecology and habitat-related diet shifts of mesofauna species in natural salt marsh habitats is virtually unknown. Therefore, we investigated the effects of natural disturbance (inundation frequency) on community structure, food web complexity and resource use of soil mesofauna using stable isotope analysis (15N, 13C) in three salt marsh zones. In this intertidal habitat, the pioneer zone is exposed to inundations twice a day, but lower and upper salt marshes are less frequently inundated based on shore height. The mesofauna comprised 86 species / taxa dominated by Collembola, Oribatida and Mesostigmata. Shifts in environmental disturbances influenced the structure of food webs, diversity and density declined strongly from the land to the sea pointing to the importance of increasing levels of inundation frequency. Accordingly, the reduced diversity and density was associated by a simplification of the food web in the pioneer zone as compared to the less inundated lower and upper salt marsh with a higher number of trophic levels. Strong variations in δ15N signatures demonstrated that mesofauna species are feeding at multiple trophic levels. Primary decomposers were low and most mesofauna species functioned as secondary decomposers or predators including second order predators or scavengers. The results document that major decomposer taxa, such as Collembola and Oribatida, are more diverse than previously assumed and predominantly dwell on autochthonous resources of the respective salt marsh zone. The results

Detection of fallout 241Am in U.S. Atlantic salt marsh soils

NASA Astrophysics Data System (ADS)

Boyd, B. M.; Sommerfield, C. K.

2017-09-01

We report the presence of the fallout radionuclide 241Am (t1/2 = 433 years) in salt marsh soils from two U.S. Atlantic estuaries and discuss its utility as a particle tracer and geochronometer. This work is motivated by the knowledge that 137Cs, the most widely used geochronometer in environmental studies, will decay to extinction during the next century. At the same time, levels of 241Am, produced by radioactive decay of fallout 241Pu, will continue to increase on Earth's surface as they have since the height of atmospheric nuclear weapons testing in the 1960s. Measurements of 241Am in soils at eighteen salt marsh locations were made by non-destructive gamma spectrometry and compared to activities of 137Cs in the same samples. Results indicate that decay of fallout 241Pu can explain the presence of 241Am in the soils, and that the activities are sufficiently high to provide meaningful chronological information with acceptable confidence limits. We achieved a detection limit of 0.28-1.47 Bq kg-1 using low-energy, planar germanium detectors and 11-55 g powderized samples. Activities of 241Am (0.08-6.44 Bq kg-1) were similar in mineral- and organic-rich marsh soils indicating that soil composition does not appear to influence the initial capture of 241Pu and retention of its 241Am progeny. Given its high affinity for fine particles, long half-life, and ease of measurement by non-destructive gamma spectrometry, 241Am has potential to serve as an alternative to 137Cs geochronometry in salt marshes and perhaps other estuarine and coastal environments.

Premixed Digestion Salts for Kjeldahl Determination of Total Nitrogen in Selected Forest Soils

Treesearch

B. G. Blackmon

1971-01-01

Estimates of total soil nitrogen by a standard Kjeldahl procedure and a modified procedure employing packets of premixed digestion salts were closely correlated. (r2 = 0.983). The modified procedure appears to be as reliable all the standard method for determining total nitrogen in southern alluvial forest soils.

Validation and application of a two-dimensional model to simulate soil salt transport under mulched drip irrigation

NASA Astrophysics Data System (ADS)

Jiao, Huiqing; Zhao, Chengyi; Sheng, Yu; Chen, Yan; Shi, Jianchu; Li, Baoguo

2017-04-01

Water shortage and soil salinization increasingly become the main constraints for sustainable development of agriculture in Southern Xinjiang, China. Mulched drip irrigation, as a high-efficient water-saving irrigation method, has been widely applied in Southern Xinjiang for cotton production. In order to analyze the reasonability of describing the three-dimensional soil water and salt transport processes under mulched drip irrigation with a relatively simple two-dimensional model, a field experiment was conducted from 2007 to 2015 at Aksu of Southern Xinjiang, and soil water and salt transport processes were simulated through the three-dimensional and two-dimensional models based on COMSOL. Obvious differences were found between three-dimensional and two-dimensional simulations for soil water flow within the early 12 h of irrigation event and for soil salt transport in the area within 15 cm away from drip tubes during the whole irrigation event. The soil water and salt contents simulated by the two-dimensional model, however, agreed well with the mean values between two adjacent emitters simulated by the three-dimensional model, and also coincided with the measurements as corresponding RMSE less than 0.037 cm3 cm-3 and 1.80 g kg-1, indicating that the two-dimensional model was reliable for field irrigation management. Subsequently, the two-dimensional model was applied to simulate the dynamics of soil salinity for five numerical situations and for a widely adopted irrigation pattern in Southern Xinjiang (about 350 mm through mulched drip irrigation during growing season of cotton and total 400 mm through flooding irrigations before sowing and after harvesting). The simulation results indicated that the contribution of transpiration to salt accumulation in root layer was about 75% under mulched drip irrigation. Moreover, flooding irrigations before sowing and after harvesting were of great importance for salt leaching of arable layer, especially in bare strip where

Seasonal variation in apparent conductivity and soil salinity at two Narragansett Bay salt marshes

EPA Science Inventory

Measurement of the apparent conductivity of salt marsh sediments using electromagnetic induction (EMI) is a rapid alternative to traditional methods of salinity determination that can be used to map soil salinity across a marsh surface. Soil salinity measures can provide informat...

Microspatial ecotone dynamics at a shifting range limit: plant-soil variation across salt marsh-mangrove interfaces.

PubMed

Yando, E S; Osland, M J; Hester, M W

2018-05-01

Ecotone dynamics and shifting range limits can be used to advance our understanding of the ecological implications of future range expansions in response to climate change. In the northern Gulf of Mexico, the salt marsh-mangrove ecotone is an area where range limits and ecotone dynamics can be studied in tandem as recent decreases in winter temperature extremes have allowed for mangrove expansion at the expense of salt marsh. In this study, we assessed aboveground and belowground plant-soil dynamics across the salt marsh-mangrove ecotone quantifying micro-spatial patterns in horizontal extent. Specifically, we studied vegetation and rooting dynamics of large and small trees, the impact of salt marshes (e.g. species and structure) on mangroves, and the influence of vegetation on soil properties along transects from underneath the mangrove canopy into the surrounding salt marsh. Vegetation and rooting dynamics differed in horizontal reach, and there was a positive relationship between mangrove tree height and rooting extent. We found that the horizontal expansion of mangrove roots into salt marsh extended up to eight meters beyond the aboveground boundary. Variation in vegetation structure and local hydrology appear to control mangrove seedling dynamics. Finally, soil carbon density and organic matter did not differ within locations across the salt marsh-mangrove interface. By studying aboveground and belowground variation across the ecotone, we can better predict the ecological effects of continued range expansion in response to climate change.

Microspatial ecotone dynamics at a shifting range limit: plant–soil variation across salt marsh–mangrove interfaces

USGS Publications Warehouse

Yando, Erik S.; Osland, Michael J.; Hester, Mark H.

2018-01-01

Ecotone dynamics and shifting range limits can be used to advance our understanding of the ecological implications of future range expansions in response to climate change. In the northern Gulf of Mexico, the salt marsh–mangrove ecotone is an area where range limits and ecotone dynamics can be studied in tandem as recent decreases in winter temperature extremes have allowed for mangrove expansion at the expense of salt marsh. In this study, we assessed aboveground and belowground plant–soil dynamics across the salt marsh–mangrove ecotone quantifying micro-spatial patterns in horizontal extent. Specifically, we studied vegetation and rooting dynamics of large and small trees, the impact of salt marshes (e.g. species and structure) on mangroves, and the influence of vegetation on soil properties along transects from underneath the mangrove canopy into the surrounding salt marsh. Vegetation and rooting dynamics differed in horizontal reach, and there was a positive relationship between mangrove tree height and rooting extent. We found that the horizontal expansion of mangrove roots into salt marsh extended up to eight meters beyond the aboveground boundary. Variation in vegetation structure and local hydrology appear to control mangrove seedling dynamics. Finally, soil carbon density and organic matter did not differ within locations across the salt marsh-mangrove interface. By studying aboveground and belowground variation across the ecotone, we can better predict the ecological effects of continued range expansion in response to climate change.

Responses of Water and Salt Parameters to Groundwater Levels for Soil Columns Planted with Tamarix chinensis

PubMed Central

Xia, Jiangbao; Zhao, Ximei; Chen, Yinping; Fang, Ying; Zhao, Ziguo

2016-01-01

Groundwater is the main water resource for plant growth and development in the saline soil of the Yellow River Delta in China. To investigate the variabilities and distributions of soil water and salt contents at various groundwater level (GL), soil columns with planting Tamarix chinensis Lour were established at six different GL. The results demonstrated the following: With increasing GL, the relative soil water content (RWC) declined significantly, whereas the salt content (SC) and absolute soil solution concentration (CS) decreased after the initial increase in the different soil profiles. A GL of 1.2 m was the turning point for variations in the soil water and salt contents, and it represented the highest GL that could maintain the soil surface moist within the soil columns. Both the SC and CS reached the maximum levels in these different soil profiles at a GL of 1.2 m. With the raise of soil depth, the RWC increased significantly, whereas the SC increased after an initial decrease. The mean SC values reached 0.96% in the top soil layer; however, the rates at which the CS and RWC decreased with the GL were significantly reduced. The RWC and SC presented the greatest variations at the medium (0.9–1.2 m) and shallow water levels (0.6 m) respectively, whereas the CS presented the greatest variation at the deep water level (1.5–1.8 m).The RWC, SC and CS in the soil columns were all closely related to the GL. However, the correlations among the parameters varied greatly within different soil profiles, and the most accurate predictions of the GL were derived from the RWC in the shallow soil layer or the SC in the top soil layer. A GL at 1.5–1.8 m was moderate for planting T. chinensis seedlings under saline groundwater conditions. PMID:26730602

Impact of slope inclination on salt accumulation

NASA Astrophysics Data System (ADS)

Nachshon, Uri

2017-04-01

Field measurements indicated on high variability in salt accumulation along natural and cultivated slopes, even for relatively homogeneous soil conditions. It was hypothesised that slope inclination has an impact on the location of salt accumulation along the slope. A set of laboratory experiments and numerical models were used to explore the impact of slope inclination on salt accumulation. It was shown, experimentally, that for conditions of saline water source at the lower boundary of the slope - salt accumulates in low concentrations and homogeneously along the entire slope, for moderate slopes. However, as inclination increases high salt concentrations were observed at the upper parts of the slope, leaving the lower parts of the slope relatively free of salt. The traditional flow and transport models did not predict the experimental observations as they indicated also for the moderate slopes on salt accumulation in the elevated parts of the slope, away of the saline water source. Consequently - a conceptual model was raised to explain the laboratory observations. It was suggested that the interactions between slope angle, evaporation rates, hydraulic conductivity of the medium and distribution of wetness along the slope affect the saline water flow path through the medium. This lead to preferential flow path close to the soil-atmosphere interface for the steep slopes, which leads to constant wash of the salts from the evaporation front upward towards the slope upper parts, whereas for the moderate slopes, flow path is below the soil-atmosphere interface, therefore salt that accumulates at the evaporation front is not being transported upward. Understanding of salt dynamics along slopes is important for agricultural and natural environments, as well as for civil engineering purposes. Better understanding of the salt transport processes along slopes will improve our ability to minimize and to cope with soil salinization processes. The laboratory experiments and

Introducing a decomposition rate modifier in the Rothamsted Carbon Model to predict soil organic carbon stocks in saline soils.

PubMed

Setia, Raj; Smith, Pete; Marschner, Petra; Baldock, Jeff; Chittleborough, David; Smith, Jo

2011-08-01

Soil organic carbon (SOC) models such as the Rothamsted Carbon Model (RothC) have been used to estimate SOC dynamics in soils over different time scales but, until recently, their ability to accurately predict SOC stocks/carbon dioxide (CO(2)) emissions from salt-affected soils has not been assessed. Given the large extent of salt-affected soils (19% of the 20.8 billion ha of arable land on Earth), this may lead to miss-estimation of CO(2) release. Using soils from two salt-affected regions (one in Punjab, India and one in South Australia), an incubation study was carried out measuring CO(2) release over 120 days. The soils varied both in salinity (measured as electrical conductivity (EC) and calculated as osmotic potential using EC and water content) and sodicity (measured as sodium adsorption ratio, SAR). For soils from both regions, the osmotic potential had a significant positive relationship with CO(2)-C release, but no significant relationship was found between SAR and CO(2)-C release. The monthly cumulative CO(2)-C was simulated using RothC. RothC was modified to take into account reductions in plant inputs due to salinity. A subset of non-salt-affected soils was used to derive an equation for a "lab-effect" modifier to account for changes in decomposition under lab conditions and this modifier was significantly related with pH. Using a subset of salt-affected soils, a decomposition rate modifier (as a function of osmotic potential) was developed to match measured and modelled CO(2)-C release after correcting for the lab effect. Using this decomposition rate modifier, we found an agreement (R(2) = 0.92) between modelled and independently measured data for a set of soils from the incubation experiment. RothC, modified by including reduced plant inputs due to salinity and the salinity decomposition rate modifier, was used to predict SOC stocks of soils in a field in South Australia. The predictions clearly showed that SOC stocks are reduced in saline soils

An experimental study on the bio-surfactant-assisted remediation of crude oil and salt contaminated soils.

PubMed

Zhang, Wen; Li, Jianbing; Huang, Guohe; Song, Weikun; Huang, Yuefei

2011-01-01

The effect of bio-surfactant (rhamnolipid) on the remediation of crude oil and salt contaminated soil was investigated in this study. The experimental results indicated that there was a distinct decline of total petroleum hydrocarbon (TPH) concentration within the soil when using rhamnolipid during a remediation period of 30 days, with maximum TPH reduction of 86.97%. The most effective remediation that was observed was with rhamnolipid at a concentration of 2 CMC in soil solution, and a first-order TPH degradation rate constant of 0.0866 d(-1). The results also illustrated that salts in soil had a negative impact on TPH reduction, and the degradation rate was negatively correlated with NaCl concentration in soil solution. The analysis of soil TPH fractions indicated that there was a significant reduction of C13-C30 during the remediation process when using bio-surfactant.

How salt lakes affect atmospheric new particle formation: A case study in Western Australia.

PubMed

Kamilli, K A; Ofner, J; Krause, T; Sattler, T; Schmitt-Kopplin, P; Eitenberger, E; Friedbacher, G; Lendl, B; Lohninger, H; Schöler, H F; Held, A

2016-12-15

New particle formation was studied above salt lakes in-situ using a mobile aerosol chamber set up above the salt crust and organic-enriched layers of seven different salt lakes in Western Australia. This unique setup made it possible to explore the influence of salt lake emissions on atmospheric new particle formation, and to identify interactions of aqueous-phase and gas-phase chemistry. New particle formation was typically observed at enhanced air temperatures and enhanced solar irradiance. Volatile organic compounds were released from the salt lake surfaces, probably from a soil layer enriched in organic compounds from decomposed leaf litter, and accumulated in the chamber air. After oxidation of these organic precursor gases, the reaction products contributed to new particle formation with observed growth rates from 2.7 to 25.4nmh -1 . The presence of ferrous and ferric iron and a drop of pH values in the salt lake water just before new particle formation events indicated that organic compounds were also oxidized in the aqueous phase, affecting the new particle formation process in the atmosphere. The contribution of aqueous-phase chemistry to new particle formation is assumed, as a mixture of hundreds of oxidized organic compounds was characterized with several analytical techniques. This chemically diverse composition of the organic aerosol fraction contained sulfur- and nitrogen-containing organic compounds, and halogenated organic compounds. Coarse mode particles were analyzed using electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. Ultra-high resolution mass spectrometry was applied to analyze filter samples. A targeted mass spectral analysis revealed the formation of organosulfates from monoterpene precursors and two known tracers for secondary organic aerosol formation from atmospheric oxidation of 1,8-cineole, which indicates that a complex interplay of aqueous-phase and gas-phase oxidation of monoterpenes contributes to

Biodiversity of arbuscular mycorrhizal fungi in roots and soils of two salt marshes.

PubMed

Wilde, Petra; Manal, Astrid; Stodden, Marc; Sieverding, Ewald; Hildebrandt, Ulrich; Bothe, Hermann

2009-06-01

The occurrence of arbuscular mycorrhizal fungi (AMF) was assessed by both morphological and molecular criteria in two salt marshes: (i) a NaCl site of the island Terschelling, Atlantic Coast, the Netherlands and (ii) a K(2)CO(3) marsh at Schreyahn, Northern Germany. The overall biodiversity of AMF, based on sequence analysis, was comparably low in roots at both sites. However, the morphological spore analyses from soil samples of both sites exhibited a higher AMF biodiversity. Glomus geosporum was the only fungus of the Glomerales that was detected both as spores in soil samples and in roots of the AMF-colonized salt plants Aster tripolium and Puccinellia sp. at both saline sites and on all sampling dates (one exception). In roots, sequences of Glomus intraradices prevailed, but this fungus could not be identified unambiguously from DNA of soil spores. Likewise, Glomus sp. uncultured, only deposited as sequence in the database, was widely detected by DNA sequencing in root samples. All attempts to obtain the corresponding sequences from spores isolated from soil samples failed consistently. A small sized Archaeospora sp. was detected, either/or by morphological and molecular analyses, in roots or soil spores, in dead AMF spores or orobatid mites. The study noted inconsistencies between morphological characterization and identification by DNA sequencing of the 5.8S rDNA-ITS2 region or part of the 18S rDNA gene. The distribution of AMF unlikely followed the salt gradient at both sites, in contrast to the zone formation of plant species. Zygotes of the alga Vaucheria erythrospora (Xanthophyceae) were retrieved and should not be misidentified with AMF spores.

Response of edible amaranth cultivar to salt stress led to Cd mobilization in rhizosphere soil: A metabolomic analysis.

PubMed

Guo, Shi-Hong; Hu, Ni; Li, Qu-Sheng; Yang, Ping; Wang, Li-Li; Xu, Zhi-Min; Chen, Hui-Jun; He, Bao-Yan; Zeng, Eddy Y

2018-05-31

The present study aimed to investigate the metabolic response of edible amaranth cultivars to salt stress and the induced rhizosphere effects on Cd mobilization in soil. Two edible amaranth cultivars (Amaranthus mangostanus L.), Quanhong (low-Cd accumulator; LC) and Liuye (high-Cd accumulator; HC), were subject to salinity treatment in both soil and hydroponic cultures. The total amount of mobilized Cd in rhizosphere soil under salinity treatment increased by 2.78-fold in LC cultivar and 4.36-fold in HC cultivar compared with controls, with 51.2% in LC cultivar and 80.5% in HC cultivar being attributed to biological mobilization of salinity. Multivariate statistical analysis generated from metabolite profiles in both rhizosphere soil and root revealed clear discrimination between control and salt treated samples. Tricarboxylic acid cycle in root was up-regulated to cope with salinity treatment, which promoted release of organic acids from root. The increased accumulation of organic acids in rhizosphere under salt stress obviously promoted soil Cd mobility. These results suggested that salinity promoted release of organic acids from root and enhanced soil Cd mobilization and accumulation in edible amaranth cultivar in soil culture. Copyright © 2018 Elsevier Ltd. All rights reserved.

Estimating rangeland runoff, soil erosion, and salt mobility and transport processes

USDA-ARS?s Scientific Manuscript database

Over 55% of sediment and salts entering the Colorado River are derived from accelerated soil erosion from federal rangelands with damages estimated to be $385 million per year. About 55% of the loading is derived from rangelands. This suggests a significant potential to reduce dissolved-solids loa...

Gibberellins Producing Endophytic Fungus Porostereum spadiceum AGH786 Rescues Growth of Salt Affected Soybean

PubMed Central

Hamayun, Muhammad; Hussain, Anwar; Khan, Sumera A.; Kim, Ho-Youn; Khan, Abdul L.; Waqas, Muhammad; Irshad, Muhammad; Iqbal, Amjad; Rehman, Gauhar; Jan, Samin; Lee, In-Jung

2017-01-01

In the pursuit of sustainable agriculture through environment and human health friendly practices, we evaluated the potential of a novel gibberellins (GAs) producing basidiomycetous endophytic fungus Porostereum spadiceum AGH786, for alleviating salt stress and promoting health benefits of soybean. Soybean seedlings exposed to different levels of NaCl stress (70 and 140 mM) under greenhouse conditions, were inoculated with the AGH786 strain. Levels of phytohormones including GAs, JA and ABA, and isoflavones were compared in control and the inoculated seedlings to understand the mechanism through which the stress is alleviated. Gibberellins producing endophytic fungi have been vital for promoting plant growth under normal and stress conditions. We report P. spadiceum AGH786 as the ever first GAs producing basidiomycetous fungus capable of producing six types of GAs. In comparison to the so for most efficient GAs producing Gibberella fujikuroi, AGH786 produced significantly higher amount of the bioactive GA3. Salt-stressed phenotype of soybean seedlings was characterized by low content of GAs and high amount of ABA and JA with reduced shoot length, biomass, leaf area, chlorophyll contents, and rate of photosynthesis. Mitigation of salt stress by AGH786 was always accompanied by high GAs, and low ABA and JA, suggesting that this endophytic fungus reduces the effect of salinity by modulating endogenous phytohormones of the seedlings. Additionally, this strain also enhanced the endogenous level of two isoflavones including daidzen and genistein in soybean seedlings under normal as well as salt stress conditions as compared to their respective controls. P. spadiceum AGH786 boosted the NaCl stress tolerance and growth in soybean, by modulating seedlings endogenous phytohormones and isoflavones suggesting a valuable contribution of this potent fungal biofertilizer in sustainable agriculture in salt affected soils. PMID:28473818

[Deposition and burial of organic carbon in coastal salt marsh: research progress].

PubMed

Cao, Lei; Song, Jin-Ming; Li, Xue-Gang; Yuan, Hua-Mao; Li, Ning; Duan, Li-Qin

2013-07-01

Coastal salt marsh has higher potential of carbon sequestration, playing an important role in mitigating global warming, while coastal saline soil is the largest organic carbon pool in the coastal salt marsh carbon budget. To study the carbon deposition and burial in this soil is of significance for clearly understanding the carbon budget of coastal salt marsh. This paper summarized the research progress on the deposition and burial of organic carbon in coastal salt marsh from the aspects of the sources of coastal salt marsh soil organic carbon, soil organic carbon storage and deposition rate, burial mechanisms of soil organic carbon, and the relationships between the carbon sequestration in coastal salt marsh and the global climate change. Some suggestions for the future related researches were put forward: 1) to further study the underlying factors that control the variability of carbon storage in coastal salt marsh, 2) to standardize the methods for measuring the carbon storage and the deposition and burial rates of organic carbon in coastal salt marsh, 3) to quantify the lateral exchange of carbon flux between coastal salt marsh and adjacent ecosystems under the effects of tide, and 4) to approach whether the effects of global warming and the increased productivity could compensate for the increase of the organic carbon decomposition rate resulted from sediment respiration. To make clear the driving factors determining the variability of carbon sequestration rate and how the organic carbon storage is affected by climate change and anthropogenic activities would be helpful to improve the carbon sequestration capacity of coastal salt marshes in China.

Mathematical simulation of water and salt transfer in geosystems of solonetzic soils in the Northern Caspian region

NASA Astrophysics Data System (ADS)

Golovanov, A. I.; Sotneva, N. I.

2009-03-01

The Dzhanybek two-dimensional radial-axial mathematical model was developed for water and salt transfer in geosystems of solonetzic complexes of the Northern Caspian region; the model is capable of considering the geochemical links and revealing the features of migration processes between the conjugated elements of the microcatena. The simulation results suggested that the stabilization of salinization-desalinization processes occurs under stable weather conditions within approximately 100 years. When the weather conditions changed (the total moisture pool of the area increased from 1978), the simulation results indicated a tendency toward salinization of dark-colored soils in microdepressions and removal of salts in the upper 1-m thick soil layer on microhighs and microslopes. Predictions for 2040 showed that a deep accumulation of salts in microdepressions and desalinization of soils of microhighs and microslopes will occur under the current weather conditions. Thus, the changes in the halogeochemical capacity of geosystems of solonetzic complexes primarily depend on the climatic conditions, although the capacity value remains almost constant with increasing total water reserves; the changes occur only between the conjugated soils of solonetzic complexes, which is of great importance for predicting the soil-geochemical status of the entire landscape.

Evaluation of soil sustainability along the Rio Grande in West Texas: changes in salt loading and organic nutrients due to farming practices

NASA Astrophysics Data System (ADS)

Cox, C. L.; Ganjegunte, G.; Borrok, D. M.; Lougheed, V.; Ma, L.; Jin, L.

2011-12-01

Growing populations demand an increase in the amount of food being produced, which in turn, puts pressure on the productivity and sustainability of soils. The use of flood irrigation from the Rio Grande, which contains high salinity, has greatly increased the sodicity and enhanced leaching of the nutrients in the Rio Grande Basin. To evaluate soil health in this area, Rio Grande, soil water, drainage water, and soils from four different sites were collected during the 2011 irrigation season. Sample sites include two pecan fields (Pecan1 and Pecan 2), one cotton field (Cotton), and one alfalfa field (Alfalfa). Each site was equipped with ECH2O-5TE sensors (Decagon Devices Inc., Pullman, WA) to measure soil moisture, temperature, and electrical conductivity (EC), along with lysimeters at depths of 15, 30, and 60 cm to collect soil water samples. Soil solution, irrigation water and drainage water were analyzed for pH, EC (measure of salinity), major cation (Ca, Mg, Na and K) concentrations and soils were analyzed for sodium adsorption ratio (SAR, a measure of sodicity) using standard methods. Soil extraction data suggests that water-soluble cation concentrations increase with depth and are significantly higher in clay-rich soils than sandy ones. Na is the most dominant water-soluble cation with it's concentrations ranging from 0.4 to 5.6 cmolc kg-1. Among all crop types, Cotton soils have the highest amount of water-soluble cations. Preliminary data shows that in the Cotton, Pecan 1 and Pecan 2 sites, soil sodicity increases with depth and becomes greater than 13 mmols1/2 L-1/2 at 30 cm below ground surface, while Alfalfa soils are generally less sodic. Overall, Cotton soils had the highest sodicity, up to 19.2 mmols1/2 L-1/2, which is well above the tolerance level of this crop. Sodicity affects soil permeability, and coincides with areas of high clay content. These observations are in agreement with the facts that pecan orchards are more intensively irrigated and

A comparison of hydroponic and soil-based screening methods to identify salt tolerance in the field in barley

PubMed Central

Tavakkoli, Ehsan; Fatehi, Foad; Rengasamy, Pichu; McDonald, Glenn K.

2012-01-01

Success in breeding crops for yield and other quantitative traits depends on the use of methods to evaluate genotypes accurately under field conditions. Although many screening criteria have been suggested to distinguish between genotypes for their salt tolerance under controlled environmental conditions, there is a need to test these criteria in the field. In this study, the salt tolerance, ion concentrations, and accumulation of compatible solutes of genotypes of barley with a range of putative salt tolerance were investigated using three growing conditions (hydroponics, soil in pots, and natural saline field). Initially, 60 genotypes of barley were screened for their salt tolerance and uptake of Na+, Cl–, and K+ at 150 mM NaCl and, based on this, a subset of 15 genotypes was selected for testing in pots and in the field. Expression of salt tolerance in saline solution culture was not a reliable indicator of the differences in salt tolerance between barley plants that were evident in saline soil-based comparisons. Significant correlations were observed in the rankings of genotypes on the basis of their grain yield production at a moderately saline field site and their relative shoot growth in pots at ECe 7.2 [Spearman’s rank correlation (rs)=0.79] and ECe 15.3 (rs=0.82) and the crucial parameter of leaf Na+ (rs=0.72) and Cl– (rs=0.82) concentrations at ECe 7.2 dS m−1. This work has established screening procedures that correlated well with grain yield at sites with moderate levels of soil salinity. This study also showed that both salt exclusion and osmotic tolerance are involved in salt tolerance and that the relative importance of these traits may differ with the severity of the salt stress. In soil, ion exclusion tended to be more important at low to moderate levels of stress but osmotic stress became more important at higher stress levels. Salt exclusion coupled with a synthesis of organic solutes were shown to be important components of salt

Production of oxygen from lunar soil by molten salt electrolysis

NASA Technical Reports Server (NTRS)

Keller, Rudolf

1989-01-01

A simple approach to utilizing lunar resources proposes to dissolve lunar soil, without or with little beneficiation, in a suitable molten salt and to electrolyze the oxides to oxygen and a metal byproduct. The envisioned process and the required technological advances are discussed. Promising electrolysis conditions have been identified in a recent experimental program to manufacture silicon and aluminum from anorthite.

Bioretention column study of bacteria community response to salt-enriched artificial stormwater.

PubMed

Endreny, Theodore; Burke, David J; Burchhardt, Kathleen M; Fabian, Mark W; Kretzer, Annette M

2012-01-01

Cold climate cities with green infrastructure depend on soil bacteria to remove nutrients from road salt-enriched stormwater. Our research examined how bacterial communities in laboratory columns containing bioretention media responded to varying concentrations of salt exposure from artificial stormwater and the effect of bacteria and salt on column effluent concentrations. We used a factorial design with two bacteria treatments (sterile, nonsterile) and three salt concentrations (935, 315, and 80 ppm), including a deionized water control. Columns were repeatedly saturated with stormwater or deionized and then drained throughout 5 wk, with the last week of effluent analyzed for water chemistry. To examine bacterial communities, we extracted DNA from column bioretention media at time 0 and at week 5 and used molecular profiling techniques to examine bacterial community changes. We found that bacterial community taxa changed between time 0 and week 5 and that there was significant separation between taxa among salt treatments. Bacteria evenness was significantly affected by stormwater treatment, but there were no differences in bacterial richness or diversity. Soil bacteria and salt treatments had a significant effect on the effluent concentration of NO, PO, Cu, Pb, and Zn based on ANOVA tests. The presence of bacteria reduced effluent NO and Zn concentrations by as much as 150 and 25%, respectively, while having a mixed effect on effluent PO concentrations. Our results demonstrate how stormwater can affect bacterial communities and how the presence of soil bacteria improves pollutant removal by green infrastructure. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Salinity controls on plant transpiration and soil water balance

NASA Astrophysics Data System (ADS)

Perri, S.; Molini, A.; Suweis, S. S.; Viola, F.; Entekhabi, D.

2017-12-01

Soil salinization and aridification represent a major threat for the food security and sustainable development of drylands. The two problems are deeply connected, and their interplay is expected to be further enhanced by climate change and projected population growth. Salt-affected land is currently estimated to cover around 1.1 Gha, and is particularly widespread in semi-arid to hyper-arid climates. Over 900 Mha of these saline/sodic soils are potentially available for crop or biomass production. Salt-tolerant plants have been recently proposed as valid solution to exploit or even remediate salinized soils. However the effects of salinity on evapotranspiration, soil water balance and the long-term salt mass balance in the soil, are still largely unexplored. In this contribution we analyze the feedback of evapotranspiration on soil salinization, with particular emphasis on the role of vegetation and plant salt-tolerance. The goal is to introduce a simple modeling framework able to shed some light on how (a) soil salinity controls plant transpiration, and (b) salinization itself is favored/impeded by different vegetation feedback. We introduce at this goal a spatially lumped stochastic model of soil moisture and salt mass dynamics averaged over the active soil depth, and accounting for the effect of salinity on evapotranspiration. Here, the limiting effect of salinity on ET is modeled through a simple plant response function depending on both salt concentration in the soil and plant salt-tolerance. The coupled soil moisture and salt mass balance is hence used to obtain the conditional steady-state probability density function (pdf) of soil moisture for given salt tolerance and salinization level, Our results show that salinity imposes a limit in the soil water balance and this limit depends on plant salt-tolerance mainly through the control of the leaching occurrence (tolerant plants exploit water more efficiently than the sensitive ones). We also analyzed the

Simulation of salinity effects on past, present, and future soil organic carbon stocks.

PubMed

Setia, Raj; Smith, Pete; Marschner, Petra; Gottschalk, Pia; Baldock, Jeff; Verma, Vipan; Setia, Deepika; Smith, Jo

2012-02-07

Soil organic carbon (SOC) models are used to predict changes in SOC stocks and carbon dioxide (CO(2)) emissions from soils, and have been successfully validated for non-saline soils. However, SOC models have not been developed to simulate SOC turnover in saline soils. Due to the large extent of salt-affected areas in the world, it is important to correctly predict SOC dynamics in salt-affected soils. To close this knowledge gap, we modified the Rothamsted Carbon Model (RothC) to simulate SOC turnover in salt-affected soils, using data from non-salt-affected and salt-affected soils in two agricultural regions in India (120 soils) and in Australia (160 soils). Recently we developed a decomposition rate modifier based on an incubation study of a subset of these soils. In the present study, we introduce a new method to estimate the past losses of SOC due to salinity and show how salinity affects future SOC stocks on a regional scale. Because salinity decreases decomposition rates, simulations using the decomposition rate modifier for salinity suggest an accumulation of SOC. However, if the plant inputs are also adjusted to reflect reduced plant growth under saline conditions, the simulations show a significant loss of soil carbon in the past due to salinization, with a higher average loss of SOC in Australian soils (55 t C ha(-1)) than in Indian soils (31 t C ha(-1)). There was a significant negative correlation (p < 0.05) between SOC loss and osmotic potential. Simulations of future SOC stocks with the decomposition rate modifier and the plant input modifier indicate a greater decrease in SOC in saline than in non-saline soils under future climate. The simulations of past losses of SOC due to salinity were repeated using either measured charcoal-C or the inert organic matter predicted by the Falloon et al. equation to determine how much deviation from the Falloon et al. equation affects the amount of plant inputs generated by the model for the soils used in this study

The effects of salinity in the soil water balance: A Budyko's approach

NASA Astrophysics Data System (ADS)

Perri, S.; Viola, F.; Molini, A.

2017-12-01

Soil degradation and water scarcity pose important constraints on productivity and development of arid and semi-arid countries. Among the main causes of loss of soil fertility, aridification and soil salinization are deeply connected threats enhanced by climate change. Assessing water availability is fundamental for a large number of applications especially in arid regions. An approach often adopted to estimate the long-term rainfall partitioning into evapotranspiration and runoff is the Budyko's curve. However, the classical Budyko framework might not be able to properly reproduce the water balance in salt affected basins, especially under elevated soil salinization conditions. Salinity is a limiting factor for plant transpiration (as well as growth) affecting both short and long term soil moisture dynamics and ultimately the hydrologic balance. Soluble salts cause a reduction of soil water potential similar to the one arising from droughts, although plant adaptations to soil salinity show extremely different traits and can vary from species to species. In a similar context, the salt-tolerance plants are expected to control the amount of soil moisture lost to transpiration in saline soils, also because salinity reduces evaporation. We propose a simple framework to include the effects of salinization on the surface energy and water balance within a simple Budyko approach. By introducing the effects of salinity in the stochastic water balance we are able to include the influence of vegetation type (i.e. in terms of salt-tolerance) on evapotranspiration-runoff partitioning under different climatic conditions. The water balance components are thus compared to data obtained from arid salt-affected regions.

Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

PubMed Central

Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

2015-01-01

Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

NASA Astrophysics Data System (ADS)

Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

2015-10-01

Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.

Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence.

PubMed

Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

2015-10-27

Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.

Diachronic analysis of salt-affected areas using remote sensing techniques: the case study of Biskra area, Algeria

NASA Astrophysics Data System (ADS)

Afrasinei, Gabriela M.; Melis, Maria T.; Buttau, Cristina; Bradd, John M.; Arras, Claudio; Ghiglieri, Giorgio

2015-10-01

In the Wadi Biskra arid and semi-arid area, sustainable development is limited by land degradation, such as secondary salinization of soils. As an important high quality date production region of Algeria, it needs continuous monitoring of desertification indicators, since the bio-physical setting defines it as highly exposed to climate-related risks. For this particular study, for which little ground truth data was possible to acquire, we set up an assessment of appropriate methods for the identification and change detection of salt-affected areas, involving image interpretation and processing techniques employing Landsat imagery. After a first phase consisting of a visual interpretation study of the land cover types, two automated classification approaches were proposed and applied for this specific study: decision tree classification and principal components analysis (PCA) of Knepper ratios. Five of the indices employed in the Decision Tree construction were set up within the current study, among which we propose a salinity index (SMI) for the extraction of highly saline areas. The results of the 1984 to 2014 diachronic analysis of salt - affected areas variation were supported by the interpreted land cover map for accuracy estimation. Connecting the outputs with auxiliary bio-physical and socio-economic data, comprehensive results are discussed, which were indispensable for the understanding of land degradation dynamics and vulnerability to desertification. One aspect that emerged was the fact that the expansion of agricultural land in the last three decades may have led and continue to contribute to a secondary salinization of soils. This study is part of the WADIS-MAR Demonstration Project, funded by the European Commission through the Sustainable Water Integrated Management (SWIM) Program (www.wadismar.eu).

Salt-driven interactions between Pistacia lentiscus and Salsola inermis.

PubMed

Barazani, Oz; Golan-Goldhirsh, Avi

2009-11-01

. Interestingly, germination of S. inermis was inhibited in medium containing salt, but the salt was obligatory for further growth, development, and fast biomass production. These results explained the observation of large biomass accumulation in the more saline soil around the deciduous P. atlantica and P. chinensis and the lack of development in the salt-depleted soil around the salt-tolerant accumulator P. lentiscus. Soil salinity around Pistacia trees critically affects the growth of S. inermis. Inhibition of S. inermis growth, but not germination, around the evergreen P. lentiscus, stems from the latter's ability to deplete salt from its surroundings. The results indicated that P. lentiscus is able to tolerate and accumulate salt, which we assume contributes to its wide distribution along the Mediterranean coast in Israel. Recommendations and perspectives While the phytoremediation potential of Salsola spp. has been explored to some extent, this of P. lentiscus has not been tested and proven before. The results suggest that the evergreen perennial salt-tolerant P. lentiscus can be recommended for horticulture purposes and soil stabilization in relatively saline environments.

Plant osmoregulation as an emergent water-saving adaptation under salt-stress conditions

NASA Astrophysics Data System (ADS)

Perri, S.; Entekhabi, D.; Molini, A.

2017-12-01

Ecohydrological models have been widely used in studying plant-environment relations and hydraulic traits in response to water, light and nutrient limitations. In this context, models become a tool to investigate how plants exploit available resources to maximize transpiration and growth, eventually pointing out possible pathways to adaptation. In contrast, ecohydrologists have rarely focused on the effects of salinity on plant transpiration, which are commonly considered marginal in terrestrial biomes. The effect of salinity, however, cannot be neglected in the case of salt affected soils - estimated to cover over 9 billion ha worldwide - and in intertidal and coastal ecosystems. The objective of this study is to model the effects of salinity on plant-water relations in order to better understand the interplay of soil hyperosmotic conditions and osmoregulation strategies in determining different transpiration patterns. Salinity reduces the water potential, therefore is expected to affect the plant hydraulics and reduce plant conductance (eventually leading to cavitation for very high salt concentrations). Also, plant adaptation to short and long-term exposure to salinity comes into place to maintain an efficient water and nutrients uptake. We introduce a parsimonious soil-plant-atmosphere continuum (SPAC) model that incorporates parameterizations for morphological, physiological and biochemical mechanisms involving varying salt concentrations in the soil water solution. Transpiration is expressed as a function of soil water salinity and salt-mediated water flows within the SPAC (the conceptual representation of the model is shown in Figure c). The model is used to explain a paradox observed in salt-tolerant plants where maximum transpiration occurs at an intermediate value of salinity (CTr,max), and is lower in more fresh (CTr,max) and more saline (C>CTr,max) conditions (Figure a and b). In particular, we show that - in salt-tolerant species - osmoregulation

Modeling salt movement and halophytic crop growth on marginal lands with the APEX model

NASA Astrophysics Data System (ADS)

Goehring, N.; Saito, L.; Verburg, P.; Jeong, J.; Garrett, A.

2016-12-01

Saline soils negatively impact crop productivity in nearly 20% of irrigated agricultural lands worldwide. At these saline sites, cultivation of highly salt-tolerant plants, known as halophytes, may increase productivity compared to conventional salt-sensitive crops (i.e., glycophytes), thereby increasing the economic potential of marginal lands. Through a variety of mechanisms, halophytes are more effective than glycophytes at excluding, accumulating, and secreting salts from their tissues. Each mechanism can have a different impact on the salt balance in the plant-soil-water system. To date, little information is available to understand the long-term impacts of halophyte cultivation on environmental quality. This project utilizes the Agricultural Policy/Environmental Extender (APEX) model, developed by the US Department of Agriculture, to model the growth and production of two halophytic crops. The crops being modeled include quinoa (Chenopodium quinoa), which has utilities for human consumption and forage, and AC Saltlander green wheatgrass (Elymus hoffmannii), which has forage utility. APEX simulates salt movement between soil layers and accounts for the salt balance in the plant-soil-water system, including salinity in irrigation water and crop-specific salt uptake. Key crop growth parameters in APEX are derived from experimental growth data obtained under non-stressed conditions. Data from greenhouse and field experiments in which quinoa and AC Saltlander were grown under various soil salinity and irrigation salinity treatments are being used to parameterize, calibrate, and test the model. This presentation will discuss progress on crop parameterization and completed model runs under different salt-affected soil and irrigation conditions.

Sodic soil properties and sunflower growth as affected by byproducts of flue gas desulfurization.

PubMed

Wang, Jinman; Bai, Zhongke; Yang, Peiling

2012-01-01

The main component of the byproducts of flue gas desulfurization (BFGD) is CaSO(4), which can be used to improve sodic soils. The effects of BFGD on sodic soil properties and sunflower growth were studied in a pot experiment. The experiment consisted of eight treatments, at four BFGD rates (0, 7.5, 15 and 22.5 t ha(-1)) and two leaching levels (750 and 1200 m(3) ha(-1)). The germination rate and yield of the sunflower increased, and the exchangeable sodium percentage (ESP), pH and total dissolved salts (TDS) in the soils decreased after the byproducts were applied. Excessive BFGD also affected sunflower germination and growth, and leaching improved reclamation efficiency. The physical and chemical properties of the reclaimed soils were best when the byproducts were applied at 7.5 t ha(-1) and water was supplied at 1200 m(3)·ha(-1). Under these conditions, the soil pH, ESP, and TDS decreased from 9.2, 63.5 and 0.65% to 7.8, 2.8 and 0.06%, and the germination rate and yield per sunflower reached 90% and 36.4 g, respectively. Salinity should be controlled by leaching when sodic soils are reclaimed with BFGD as sunflower growth is very sensitive to salinity during its seedling stage.

Atrazine and its metabolites degradation in mineral salts medium and soil using an enrichment culture.

PubMed

Kumar, Anup; Singh, Neera

2016-03-01

An atrazine-degrading enrichment culture was used to study degradation of atrazine metabolites viz. hydroxyatrazine, deethylatrazine, and deisopropylatrazine in mineral salts medium. Results suggested that the enrichment culture was able to degrade only hydroxyatrazine, and it was used as the sole source of carbon and nitrogen. Hydroxyatrazine degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as the additional sources of carbon and nitrogen, respectively. The enrichment culture could degrade high concentrations of atrazine (up to 110 μg/mL) in mineral salts medium, and neutral pH was optimum for atrazine degradation. Further, except in an acidic soil, enrichment culture was able to degrade atrazine in three soil types having different physico-chemical properties. Raising the pH of acidic soil to neutral or alkaline enabled the enrichment culture to degrade atrazine suggesting that acidic pH inhibited atrazine-degrading ability. The study suggested that the enrichment culture can be successfully utilized to achieve complete degradation of atrazine and its persistent metabolite hydroxyatrazine in the contaminated soil and water.

Physicochemical studies on Uburu Salt Lake Ebonyi State-Nigeria.

PubMed

Akubugwo, I E; Ofoegbu, C J; Ukwuoma, C U

2007-09-15

Physicochemical properties of soil (sediment) and water from Uburu salt lake were evaluated and compared with control soil and surface water from the same community. Results showed significant (p < 0.05) higher values for the heavy metals cadmium, chromium, copper, lead and zinc in the lake water relative to the control. The values of these metals in the lake soil (sediments) however, were significantly (p < 0.05) lower than the control soil. Similar significant (p < 0.05) elevations were observed in the lake water temperature, salinity, pH, calcium, magnesium, sodium, potassium, nitrate, carbonate, sulphate and phosphate levels compared to the control. Significant (p < 0.05) changes were also noted in the lake soil's pH, exchangeable acidity, nitrogen, organic carbon, calcium and magnesium levels. Also the soil texture was affected relative to the control. In a number of cases, the values of the studied parameters were higher than the permissible WHO standards. In view of these findings, cautious use of the salt lake soil and water is advocated.

Estimating degradation-related settlement in two landfill-reclaimed soils by sand-salt analogues.

PubMed

McDougall, J R; Fleming, I R; Thiel, R; Dewaele, P; Parker, D; Kelly, D

2018-04-25

Landfill reclaimed soil here refers to largely degraded materials excavated from old landfill sites, which after processing can be reinstated as more competent fill, thereby restoring the former landfill space. The success of the process depends on the presence of remaining degradable particles and their influence on settlement. Tests on salt-sand mixtures, from which the salt is removed, have been used to quantify the impact of particle loss on settlement. Where the amount of particle loss is small, say 10% by mass or less, settlements are small and apparently independent of lost particle size. A conceptual model is presented to explain this behaviour in terms of nestling particles and strong force chains. At higher percentages of lost particles, greater rates of settlement together with some sensitivity to particle size were observed. The conceptual model was then applied to two landfill reclaimed soils, the long-term settlements of which were found to be consistent with the conceptual model suggesting that knowledge of particle content and relative size are sufficient to estimate the influence of degradable particles in landfill reclaimed soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ash salts and bodily affects: Witoto environmental knowledge as sexual education

NASA Astrophysics Data System (ADS)

Alvaro Echeverri, Juan; Enokakuiodo Román-Jitdutjaaño, Oscar

2013-03-01

This letter addresses the indigenous discourse on a set of plant species used by the Witoto Indians of Northwest Amazonia to extract ash or vegetable salt, obtained from the combustion of the tissues of vegetable species, filtering of the ashes, and desiccation of the resulting brine. It aims to demonstrate how the study of the human condition is carried out through a reading of natural entities. The method employed is the indexical analysis of a discourse uttered by the elder Enokakuiodo in the Witoto language from 1995 to 1998, in a verbal genre called rafue, one of several genres of the ‘language of the yard of coca’. The species used to extract ash salt are conceived of as coming from the body of the Creator and as an image of the human body. The rafue of salt performs, in words and gestures, a narrative of human affects and capacities by reading ecological, biological, cultural and linguistic indices from a set of plant species. This discourse on plant species is a discourse on the control and management of bodily affects and capacities, represented as ash salts, that are lessons about sexual development which the Creator left for humanity as a guide—a ‘sexual education’.

Soil salinity decreases global soil organic carbon stocks.

PubMed

Setia, Raj; Gottschalk, Pia; Smith, Pete; Marschner, Petra; Baldock, Jeff; Setia, Deepika; Smith, Jo

2013-11-01

Saline soils cover 3.1% (397 million hectare) of the total land area of the world. The stock of soil organic carbon (SOC) reflects the balance between carbon (C) inputs from plants, and losses through decomposition, leaching and erosion. Soil salinity decreases plant productivity and hence C inputs to the soil, but also microbial activity and therefore SOC decomposition rates. Using a modified Rothamsted Carbon model (RothC) with a newly introduced salinity decomposition rate modifier and a plant input modifier we estimate that, historically, world soils that are currently saline have lost an average of 3.47 tSOC ha(-1) since they became saline. With the extent of saline soils predicted to increase in the future, our modelling suggests that world soils may lose 6.8 Pg SOC due to salinity by the year 2100. Our findings suggest that current models overestimate future global SOC stocks and underestimate net CO2 emissions from the soil-plant system by not taking salinity effects into account. From the perspective of enhancing soil C stocks, however, given the lower SOC decomposition rate in saline soils, salt tolerant plants could be used to sequester C in salt-affected areas. Copyright © 2012 Elsevier B.V. All rights reserved.

Spatial Pattern of Soil Salinity in Area Around the Yellow River Delta and Its Seasonal Dynamics over a 3-year Period

NASA Astrophysics Data System (ADS)

Lai, J.; Ouyang, Z.

2017-12-01

Salt-affected land varies spatially and seasonally in terms of soil salinity. "Bohai Granary" is a newly proposed national-level program which was aimed to improve soil quality and mining grain production potential of the salt-affected land in east China. In this work, soil samples were monthly taken at 11 sites within Wudi county in the Yellow river delta. The spatial distribution pattern of soil salinity were investigated and its seasonal variation over 36 months were discussed. Our findings indicate that the vertical distribution type of soil salinity was bottom-accumulating in the near coastal area while its gradually turned into a type of surface-accumulating as the sampling site moving towards the inner land. The peak of the soil salinity along the soil profile alternately moved upwards and downwards during the growing seasons. However, there was no evidence for the increasing of the total salt amount within the upper 100cm of soil. Moreover, the salt was mostly accumulated in the upper soil (0-40cm) during the late spring and early summer season; and winter wheat was tend to be affected severely at this stage. Therefore, special field practices (e.g. regular irrigation to leach salt, good maintenance of drainage system) should be taken to minimize the threat of soil salinity.

Effects of lead mineralogy on soil washing enhanced by ferric salts as extracting and oxidizing agents.

PubMed

Yoo, Jong-Chan; Park, Sang-Min; Yoon, Geun-Seok; Tsang, Daniel C W; Baek, Kitae

2017-10-01

In this study, we evaluated the feasibility of using ferric salts including FeCl 3 and Fe(NO 3 ) 3 as extracting and oxidizing agents for a soil washing process to remediate Pb-contaminated soils. We treated various Pb minerals including PbO, PbCO 3 , Pb 3 (CO 3 ) 2 (OH) 2 , PbSO 4 , PbS, and Pb 5 (PO 4 ) 3 (OH) using ferric salts, and compared our results with those obtained using common washing agents of HCl, HNO 3 , disodium-ethylenediaminetetra-acetic acid (Na 2 -EDTA), and citric acid. The use of 50 mM Fe(NO 3 ) 3 extracted significantly more Pb (above 96% extraction) from Pb minerals except PbSO 4 (below 55% extraction) compared to the other washing agents. In contrast, washing processes using FeCl 3 and HCl were not effective for extraction from Pb minerals because of PbCl 2 precipitation. Yet, the newly formed PbCl 2 could be dissolved by subsequent wash with distilled water under acidic conditions. When applying our washing method to remediate field-contaminated soil from a shooting range that had high concentrations of Pb 3 (CO 3 ) 2 (OH) 2 and PbCO 3 , we extracted more Pb (approximately 99% extraction) from the soil using 100 mM Fe(NO 3 ) 3 than other washing agents at the same process conditions. Our results show that ferric salts can be alternative washing agents for Pb-contaminated soils in view of their extracting and oxidizing abilities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genomic and metagenomic analysis of microbes in a soil environment affected by the 2011 Great East Japan Earthquake tsunami.

PubMed

Hiraoka, Satoshi; Machiyama, Asako; Ijichi, Minoru; Inoue, Kentaro; Oshima, Kenshiro; Hattori, Masahira; Yoshizawa, Susumu; Kogure, Kazuhiro; Iwasaki, Wataru

2016-01-14

The Great East Japan Earthquake of 2011 triggered large tsunami waves, which flooded broad areas of land along the Pacific coast of eastern Japan and changed the soil environment drastically. However, the microbial characteristics of tsunami-affected soil at the genomic level remain largely unknown. In this study, we isolated microbes from a soil sample using general low-nutrient and seawater-based media to investigate microbial characteristics in tsunami-affected soil. As expected, a greater proportion of strains isolated from the tsunami-affected soil than the unaffected soil grew in the seawater-based medium. Cultivable strains in both the general low-nutrient and seawater-based media were distributed in the genus Arthrobacter. Most importantly, whole-genome sequencing of four of the isolated Arthrobacter strains revealed independent losses of siderophore-synthesis genes from their genomes. Siderophores are low-molecular-weight, iron-chelating compounds that are secreted for iron uptake; thus, the loss of siderophore-synthesis genes indicates that these strains have adapted to environments with high-iron concentrations. Indeed, chemical analysis confirmed the investigated soil samples to be rich in iron, and culture experiments confirmed weak cultivability of some of these strains in iron-limited media. Furthermore, metagenomic analyses demonstrated over-representation of denitrification-related genes in the tsunami-affected soil sample, as well as the presence of pathogenic and marine-living genera and genes related to salt-tolerance. Collectively, the present results would provide an example of microbial characteristics of soil disturbed by the tsunami, which may give an insight into microbial adaptation to drastic environmental changes. Further analyses on microbial ecology after a tsunami are envisioned to develop a deeper understanding of the recovery processes of terrestrial microbial ecosystems.

Site Suitability Analysis for Dissemination of Salt-tolerant Rice Varieties in Southern Bangladesh

NASA Astrophysics Data System (ADS)

Sinha, D. D.; Singh, A. N.; Singh, U. S.

2014-11-01

Bangladesh is a country of 14.4 million ha geographical area and has a population density of more than 1100 persons per sq. km. Rice is the staple food crop, growing on about 72 % of the total cultivated land and continues to be the most important crop for food security of the country. A project "Sustainable Rice Seed Production and Delivery Systems for Southern Bangladesh" has been executed by the International Rice Research Institute (IRRI) in twenty southern districts of Bangladesh. These districts grow rice in about 2.9 million ha out of the country's total rice area of 11.3 million ha. The project aims at contributing to the Government of Bangladesh's efforts in improving national and household food security through enhanced and sustained productivity by using salinity-, submergence- and drought- tolerant and high yielding rice varieties. Out of the 20 project districts, 12 coastal districts are affected by the problem of soil salinity. The salt-affected area in Bangladesh has increased from about 0.83 million ha in 1973 to 1.02 million ha in 2000, and 1.05 million ha in 2009 due to the influence of cyclonic storms like "Sidr", "Laila" and others, leading to salt water intrusion in croplands. Three salinity-tolerant rice varieties have recently been bred by IRRI and field tested and released by the Bangladesh Rice Research Institute (BRRI) and Bangladesh Institute of Nuclear Agriculture (BINA). These varieties are BRRI dhan- 47 and Bina dhan-8 and - 10. However, they can tolerate soil salinity level up to EC 8-10 dSm-1, whereas the EC of soils in several areas are much higher. Therefore, a large scale dissemination of these varieties can be done only when a site suitability analysis of the area is carried out. The present study was taken up with the objective of preparing the site suitability of the salt-tolerant varieties for the salinity-affected districts of southern Bangladesh. Soil salinity map prepared by Soil Resources Development Institute of

The combined use of liming and Sarcocornia fruticosa development for phytomanagement of salt marsh soils polluted by mine wastes.

PubMed

González-Alcaraz, María Nazaret; Conesa, Héctor Miguel; Tercero, María del Carmen; Schulin, Rainer; Alvarez-Rogel, José; Egea, Consuelo

2011-02-15

The aim of this study was to evaluate the combined effects of liming and behaviour of Sarcocornia fruticosa as a strategy of phytomanagement of metal polluted salt marsh soils. Soils were taken from two polluted salt marshes (one with fine texture and pH∼6.4 and the other one with sandy texture and pH∼3.1). A lime amendment derived from the marble industry was added to each soil at a rate of 20 g kg(-1), giving four treatments: neutral soil with/without liming and acidic soil with/without liming. Cuttings of S. fruticosa were planted in pots filled with these substrates and grown for 10 months. The pots were irrigated with eutrophicated water. As expected, lime amendment decreased the soluble metal concentrations. In both soils, liming favoured the growth of S. fruticosa and enhanced the capacity of the plants to phytostabilise metals in roots. Copyright © 2010 Elsevier B.V. All rights reserved.

Effects of soil abiotic factors on the plant morphology in an intertidal salt marsh, Yellow River Delta, China

NASA Astrophysics Data System (ADS)

Li, Shanze; Cui, Baoshan; Bai, Junhong; Xie, Tian; Yan, Jiaguo; Wang, Qing; Zhang, Shuyan

2018-02-01

Plant morphology plays important role in studying biogeography in many ecosystems. Suadea salsa, as a native plant community of northern China and an important habitat for diversity of waterbirds and macrobenthos, has often been overlooked. Nowadays, S. salsa community is facing great loss due to coastal reclamation activities and natural disturbances. To maintain and restore S. salsa community, it's important to address the plant morphology across marsh zones, as well as its relationships with local soil abiotic conditions. In our studied intertidal salt marsh, we found that less flood disturbance frequency, softer soil conditions, rich soil organic matter, total carbon and total nitrogen, lower water depth and water content, less species competition will benefit S. salsa plant in the morphology of high coverage, above-ground biomass, shoot height and leaf length. Lower soil porewater salinity will benefit the below-ground biomass of S. salsa. Thus, we recommend managers help alleviate soil abiotic stresses in the intertidal salt marshes, making the soil conditions more suitable for S. salsa growth and succession.

The Presence and Distribution of Salts as a Palaeoprecipitation Proxy in Atacama Soils

NASA Astrophysics Data System (ADS)

McKay, Lucy; Claire, Mark

2016-04-01

The Atacama Desert in northern Chile (17 to 27° S) is the driest and oldest warm desert on Earth and contains unique abundances of atmospherically-derived salts such as nitrate and perchlorate (Ewing et al., 2006; Jackson et al., 2015). Near-surface accumulation of extremely soluble salts indicates a scarcity of long-term precipitation-driven leaching from Atacama soils. The prolonged absence of substantial precipitation has enabled nitrate and perchlorate to accumulate for millions of years to measurable levels, while interacting with occasional rainfall to move vertically through the soil profile. We investigate the near-surface presence and distribution of atmospherically-generated soluble salts at Earth's most arid extreme, aiming to quantify Atacama palaeoprecipitation during the Quaternary. Previous field and modelling studies have revealed a strong correlation between the depth of peak nitrate and past precipitation events in the U.S. desert southwest (Walvoord et al., 2003; Marion et al., 2008). We extend these studies to regions of much lower rainfall, and report the largest ever near-surface concentrations of nitrate and perchlorate in Earth's soils. We present salt distribution profiles from soil pits in six localities, spanning ~1000 km of the south-to-north (27° to 24° S) natural rainfall and ecosystem function gradient that spans the arid to hyperarid transition (from 20 to <1 mm rainfall y-1). Localities include the well-characterised Yungay desert research station, initially declared as the driest place on Earth beyond the limit for microbial life (McKay et al., 2003). Importantly, our nitrate and perchlorate data confirm and extend suspicions that drier localities than Yungay exist (Azua-Bustos et al., 2015). For example, our "km40" site reveals 10 mg/kg of perchlorate at the surface, with a peak of 35 mg/kg at 10 cm depth. At "PONR", perchlorate peaks at >100 mg/kg at 120 cm depth, with an astonishing 22 mg/kg at the surface. In comparison

Reflectance spectroscopy for the assessment of soil salt content in soils of the yellow river delta of China

USGS Publications Warehouse

Weng, Yongling; Gong, P.; Zhu, Z.

2008-01-01

There has been growing interest in the use of reflectance spectroscopy as a rapid and inexpensive tool for soil characterization. In this study, we collected 95 soil samples from the Yellow River Delta of China to investigate the level of soil salinity in relation to soil spectra. Sample plots were selected based on a field investigation and the corresponding soil salinity classification map to maximize variations of saline characteristics in the soil. Spectral reflectances of air-dried soil samples were measured using an Analytical Spectral Device (ASD) spectrometer (350-2500 nm) with an artificial light source. In the Yellow River Delta, the dominant chemical in the saline soil was NaCl and MgCl2. Soil spectra were analysed using two-thirds of the available samples, with the remaining one-third withheld for validation purposes. The analysis indicated that with some preprocessing, the reflectance at 1931-2123 nm and 2153-2254 nm was highly correlated with soil salt content (SSC). In the spectral region of 1931-2123 nm, the correlation R ranged from -0.80 to -0.87. In the region of 2153-2254 nm, the SSC was positively correlated with preprocessed reflectance (0.79-0.88). The preprocessing was done by fitting a convex hull to the reflectance curve and dividing the spectral reflectance by the value of the corresponding convex hull band by band. This process is called continuum removal, and the resulting ratio is called continuum removed reflectance (CR reflectance). However, the SSC did not have a high correlation with the unprocessed reflectance, and the correlation was always negative in the entire spectrum (350-2500 nm) with the strongest negative correlation at 1981 nm (R = -0.63). Moreover, we found a strong correlation (R=0.91) between a soil salinity index (SSI: Constructed using CR reflectance at 2052 nm and 2203 nm) and SSC. We estimated SSC as a function of SSI and SSI' (SSI': Constructed using unprocessed reflectance at 2052 nm and 2203 nm) using

Soil Carbon Stocks in a Shifting Ecosystem; Climate Induced Migration of Mangroves into Salt Marsh

NASA Astrophysics Data System (ADS)

Simpson, L.; Osborne, T.; Feller, I. C.

2015-12-01

Across the globe, coastal wetland vegetation distributions are changing in response to climate change. The increase in global average surface temperature has already caused shifts in the structure and distribution of many ecological communities. In parts of the southeastern United States, increased winter temperatures have resulted in the poleward range expansion of mangroves at the expense of salt marsh habitat. Our work aims to document carbon storage in the salt marsh - mangrove ecotone and any potential changes in this reservoir that may ensue due to the shifting range of this habitat. Differences in SOM and C stocks along a latitudinal gradient on the east coast of Florida will be presented. The gradient studied spans 342 km and includes pure mangrove habitat, the salt marsh - mangrove ecotone, and pure salt marsh habitat.This latitudinal gradient gives us an exceptional opportunity to document and investigate ecosystem soil C modifications as mangroves transgress into salt marsh habitat due to climatic change.

Long-term ferrocyanide application via deicing salts promotes the establishment of Actinomycetales assimilating ferrocyanide-derived carbon in soil.

PubMed

Gschwendtner, Silvia; Mansfeldt, Tim; Kublik, Susanne; Touliari, Evangelia; Buegger, Franz; Schloter, Michael

2016-07-01

Cyanides are highly toxic and produced by various microorganisms as defence strategy or to increase their competitiveness. As degradation is the most efficient way of detoxification, some microbes developed the capability to use cyanides as carbon and nitrogen source. However, it is not clear if this potential also helps to lower cyanide concentrations in roadside soils where deicing salt application leads to significant inputs of ferrocyanide. The question remains if biodegradation in soils can occur without previous photolysis. By conducting a microcosm experiment using soils with/without pre-exposition to road salts spiked with (13) C-labelled ferrocyanide, we were able to confirm biodegradation and in parallel to identify bacteria using ferrocyanide as C source via DNA stable isotope probing (DNA-SIP), TRFLP fingerprinting and pyrosequencing. Bacteria assimilating (13) C were highly similar in the pre-exposed soils, belonging mostly to Actinomycetales (Kineosporia, Mycobacterium, Micromonosporaceae). In the soil without pre-exposition, bacteria belonging to Acidobacteria (Gp3, Gp4, Gp6), Gemmatimonadetes (Gemmatimonas) and Gammaproteobacteria (Thermomonas, Xanthomonadaceae) used ferrocyanide as C source but not the present Actinomycetales. This indicated that (i) various bacteria are able to assimilate ferrocyanide-derived C and (ii) long-term exposition to ferrocyanide applied with deicing salts leads to Actinomycetales outcompeting other microorganisms for the use of ferrocyanide as C source. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Combined effects of tides, evaporation and rainfall on the soil conditions in an intertidal creek-marsh system

NASA Astrophysics Data System (ADS)

Xin, Pei; Zhou, Tingzhang; Lu, Chunhui; Shen, Chengji; Zhang, Chenming; D'Alpaos, Andrea; Li, Ling

2017-05-01

Salt marshes, distributed globally at the land-ocean interface, are a highly productive eco-system with valuable ecological functions. While salt marshes are affected by various eco-geo-hydrological processes and factors, soil moisture and salinity affect plant growth and play a key role in determining the structure and functions of the marsh ecosystem. To examine the variations of both soil parameters, we simulated pore-water flow and salt transport in a creek-marsh system subjected to spring-neap tides, evaporation and rainfall. The results demonstrated that within a sandy-loam marsh, the tide-induced pore-water circulation averted salt build-up due to evaporation in the near-creek area. In the marsh interior where the horizontal drainage was weak, density-driven flow was responsible for dissipating salt accumulation in the shallow soil layer. In the sandy-loam marsh, the combined influences of spring-neap tides, rainfall and evaporation led to the formation of three characteristic zones, c.f., a near-creek zone with low soil water saturation (i.e., well-aerated) and low pore-water salinity as affected by the semi-diurnal spring tides, a less well-aerated zone with increased salinity where drainage occurred during the neap tides, and an interior zone where evaporation and rainfall infiltration regulated the soil conditions. These characteristics, however, varied with the soil type. In low-permeability silt-loam and clay-loam marshes, the tide-induced drainage weakened and the soil conditions over a large area became dominated by evaporation and rainfall. Sea level rise was found to worsen the soil aeration condition but inhibit salt accumulation due to evaporation. These findings shed lights on the soil conditions underpinned by various hydrogeological processes, and have important implications for further investigations on marsh plant growth and ecosystem functions.

Conductivity gradients as inferred by electromagnetic-induction meter (EM38) readings within a salt-affected wetland in Saskatchewan, Canada

NASA Astrophysics Data System (ADS)

Mirck, Jaconette; Schroeder, William

2018-01-01

The change from deep-rooted grass and shrub vegetation to annual-cropping dryland farming has contributed to serious soil salinization challenges on the semi-arid North American Great Plains. In some cases, cultivation of the Great Plains has increased the availability of water, causing dominant sulfate salts to travel from the uphill areas to depressions where it will surface when water evaporates at the soil surface. A potential solution could include the replanting of the native deep-rooted vegetation, which requires knowledge of the spatial distribution of soil salinity. This study tested the soil factors influencing electromagnetic-induction meter (EM38) readings of soil salinity distribution around wetlands. The objectives were to: (1) predict growth and survival of Salix dasyclados Wimm. (cv. `India') along a salinity gradient in a small wetland, and (2) investigate whether newly established willows affected water-table fluctuations, which would indicate their phreatophytic nature or their ability to obtain their water supply from the zone of saturation. Results indicated significantly lower salinity values for sampling points with EM38 readings above 175 and 250 mS m-1 for height and survival, respectively. In addition, diurnal fluxes of the water table in areas of good willow growth and lower salinity indicated that cultivar `India' was phreatophytic in these areas and therefore has great potential for being used to combat saline seeps.

Conductivity gradients as inferred by electromagnetic-induction meter (EM38) readings within a salt-affected wetland in Saskatchewan, Canada

NASA Astrophysics Data System (ADS)

Mirck, Jaconette; Schroeder, William

2018-06-01

The change from deep-rooted grass and shrub vegetation to annual-cropping dryland farming has contributed to serious soil salinization challenges on the semi-arid North American Great Plains. In some cases, cultivation of the Great Plains has increased the availability of water, causing dominant sulfate salts to travel from the uphill areas to depressions where it will surface when water evaporates at the soil surface. A potential solution could include the replanting of the native deep-rooted vegetation, which requires knowledge of the spatial distribution of soil salinity. This study tested the soil factors influencing electromagnetic-induction meter (EM38) readings of soil salinity distribution around wetlands. The objectives were to: (1) predict growth and survival of Salix dasyclados Wimm. (cv. `India') along a salinity gradient in a small wetland, and (2) investigate whether newly established willows affected water-table fluctuations, which would indicate their phreatophytic nature or their ability to obtain their water supply from the zone of saturation. Results indicated significantly lower salinity values for sampling points with EM38 readings above 175 and 250 mS m-1 for height and survival, respectively. In addition, diurnal fluxes of the water table in areas of good willow growth and lower salinity indicated that cultivar `India' was phreatophytic in these areas and therefore has great potential for being used to combat saline seeps.

Salt stress signals shape the plant root.

PubMed

Galvan-Ampudia, Carlos S; Testerink, Christa

2011-06-01

Plants use different strategies to deal with high soil salinity. One strategy is activation of pathways that allow the plant to export or compartmentalise salt. Relying on their phenotypic plasticity, plants can also adjust their root system architecture (RSA) and the direction of root growth to avoid locally high salt concentrations. Here, we highlight RSA responses to salt and osmotic stress and the underlying mechanisms. A model is presented that describes how salinity affects auxin distribution in the root. Possible intracellular signalling pathways linking salinity to root development and direction of root growth are discussed. These involve perception of high cytosolic Na+ concentrations in the root, activation of lipid signalling and protein kinase activity and modulation of endocytic pathways. Copyright © 2011 Elsevier Ltd. All rights reserved.

[Progress on salt resistance in autopolyploid plants].

PubMed

Zhu, Hong Ju; Liu, Wen Ge

2018-04-20

Polyploidization is a key driving force that plays a vital role in the evolution of higher plants. Autopolyploid plants often demonstrate altered physiology phenomena due to the different genome composition and gene expression patterns. For example, autopolyploid plants are more resistant to stresses than their homologous diploid ancestors. Soil salinity and secondary salinization are two vital factors affecting crop production which severely limit the sustainable development of agriculture in China. Polyploid plants are important germplasm resources in crop genetic improvement due to their higher salt tolerance. Revealing the mechanism of salt tolerance in homologous plants will provide a foundation for breeding new plants with improved salt resistance. In this review, we describe the existing and ongoing characterization of the mechanism of salt tolerance in autopolyploid plants, including the salt tolerance evolution, physiology, biochemistry, cell structure and molecular level researches. Finally, we also discuss the prospects in this field by using polyploid watermelon as an example, which will be helpful in polyploid research and plant breeding.

Soil bacteria confer plant salt tolerance by tissue-specific regulation of the sodium transporter HKT1.

PubMed

Zhang, Huiming; Kim, Mi-Seong; Sun, Yan; Dowd, Scot E; Shi, Huazhong; Paré, Paul W

2008-06-01

Elevated sodium (Na(+)) decreases plant growth and, thereby, agricultural productivity. The ion transporter high-affinity K(+) transporter (HKT)1 controls Na(+) import in roots, yet dysfunction or overexpression of HKT1 fails to increase salt tolerance, raising questions as to HKT1's role in regulating Na(+) homeostasis. Here, we report that tissue-specific regulation of HKT1 by the soil bacterium Bacillus subtilis GB03 confers salt tolerance in Arabidopsis thaliana. Under salt stress (100 mM NaCl), GB03 concurrently down- and upregulates HKT1 expression in roots and shoots, respectively, resulting in lower Na(+) accumulation throughout the plant compared with controls. Consistent with HKT1 participation in GB03-induced salt tolerance, GB03 fails to rescue salt-stressed athkt1 mutants from stunted foliar growth and elevated total Na(+) whereas salt-stressed Na(+) export mutants sos3 show GB03-induced salt tolerance with enhanced shoot and root growth as well as reduced total Na(+). These results demonstrate that tissue-specific regulation of HKT1 is critical for managing Na(+) homeostasis in salt-stressed plants, as well as underscore the breadth and sophistication of plant-microbe interactions.

An overview of soil water sensors for salinity & irrigation management

USDA-ARS?s Scientific Manuscript database

Irrigation water management has to do with the appropriate application of water to soils, in terms of amounts, rates, and timing to satisfy crop water demands while protecting the soil and water resources from degradation. Accurate irrigation management is even more important in salt affected soils ...

Identification of the origin of salts in an agricultural area of SE Spain

NASA Astrophysics Data System (ADS)

Acosta, Jose A.; Faz, Angel; Kalbitz, Karsten; Jansen, Boris; Silvia, Martinez-Martinez

2010-05-01

In spite of soil salinity having been widely studied in many part of the world, origin of salinity has not been addresses in detail in some of the most productive agricultural areas of Europe (e.g. southeast of Spain). According to the European Commission, salinization affects about 1 to 3 million ha of the area of the European Union and Candidate Countries. In Europe, most of the salt-affected land surfaces are concentrated in the Mediterranean basin. In Spain, about 3% of the 3.5 million hectares of irrigated land are severely affected by salts and another 15% is at serious risk of imminent salinization. Due to the limited water resources in southeast of Spain, water with marginal quality is used for irrigation. The use of this water has led to degradation, reduction of the land's production capacity and soil salinization. The main aim of the present study was to identify the origin of the salts involved in such salinization, using classical and multivariable statistical techniques. In order to achieve this objective, surface soil samples were collected in January and July 2009 at 48 sites located in a representative lemon production area close to City of Murcia, covering a surface area of 44 km2. Soil pH, electrical conductivity, ionic composition, total organic matter, equivalent calcium carbonate, cation exchange capacity and particle size distribution were determined. The Pearson correlation coefficient, r, was used to measure the relationship between two quantitative variables and principal components analysis was used to study the correlations among anions and cations and their grouping into several factors. Results indicated that the high electrical conductivity found in the study area indeed comes from poor quality irrigation water used for agriculture. Anions and cations responsible of the salinity were chlorides, sulphates, calcium, magnesium and sodium. Mismanagement of water and traditional irrigation system resulted in salt build-up in the soil

Nitrate and Ammonium Contribute to the Distinct Nitrogen Metabolism of Populus simonii during Moderate Salt Stress

PubMed Central

Meng, Sen; Su, Li; Li, Yiming; Wang, Yinjuan; Zhang, Chunxia; Zhao, Zhong

2016-01-01

Soil salinity is a major abiotic stressor affecting plant growth. Salinity affects nitrification and ammonification in the soil, however, limited information is available on the influence of different N sources on N metabolism during salt stress. To understand the N metabolism changes in response to different N sources during moderate salt stress, we investigated N uptake, assimilation and the transcript abundance of associated genes in Populus simonii seedlings treated with moderate salt stress (75mM NaCl) under hydroponic culture conditions with nitrate (NO3-) or ammonium (NH4+). Salt stress negatively affected plant growth in both NH4+-fed and NO3--fed plants. Both NH4+ uptake and the total N concentration were significantly increased in the roots of the NH4+-fed plants during salt stress. However, the NO3- uptake and nitrate reductase (NR) and nitrite reductase (NiR) activity primarily depended on the NO3- supply and was not influenced by salt stress. Salt stress decreased glutamine synthetase (GS) and glutamate synthase (GOGAT) activity in the roots and leaves. Most genes associated with NO3-uptake, reduction and N metabolism were down-regulated or remained unchanged; while two NH4+ transporter genes closely associated with NH4+ uptake (AMT1;2 and AMT1;6) were up-regulated in response to salt stress in the NH4+-fed plants. The accumulation of different amino acid compounds was observed in the NH4+- and NO3-- fed plants during salt treatment. The results suggested that N metabolism in P. simonii plants exposed to salt enhanced salt resistance in the plants that were fed with NO3- instead of NH4+ as the sole N source. PMID:26950941

Cadmium accumulation by muskmelon under salt stress in contaminated organic soil.

PubMed

Ondrasek, Gabrijel; Gabrijel, Ondrasek; Romic, Davor; Davor, Romic; Rengel, Zed; Zed, Rengel; Romic, Marija; Marija, Romic; Zovko, Monika; Monika, Zovko

2009-03-15

Human-induced salinization and trace element contamination are widespread and increasing rapidly, but their interactions and environmental consequences are poorly understood. Phytoaccumulation, as the crucial entry pathway for biotoxic Cd into the human foodstuffs, correlates positively with rhizosphere salinity. Hypothesising that organic matter decreases the bioavailable Cd(2+) pool and therefore restricts its phytoextraction, we assessed the effects of four salinity levels (0, 20, 40 and 60 mM NaCl) and three Cd levels (0.3, 5.5 and 10.4 mg kg(-1)) in peat soil on mineral accumulation/distribution as well as vegetative growth and fruit yield parameters of muskmelon (Cucumis melo L.) in a greenhouse. Salt stress reduced shoot biomass and fruit production, accompanied by increased Na and Cl and decreased K concentration in above-ground tissues. A 25- and 50-day exposure to salinity increased Cd accumulation in leaves up to 87% and 46%, respectively. Accumulation of Cd in the fruits was up to 43 times lower than in leaves and remained unaltered by salinity. Soil contamination by Cd enhanced its accumulation in muskmelon tissues by an order of magnitude compared with non-contaminated control. In the drainage solution, concentrations of Na and Cl slightly exceeded those in the irrigation solution, whereas Cd concentration in drainage solution was lower by 2-3 orders of magnitude than the total amount added. Chemical speciation and distribution modelling (NICA-Donnan) using Visual MINTEQ showed predominance of dissolved organic ligands in Cd chemisorption and complexation in all treatments; however, an increase in salt addition caused a decrease in organic Cd complexes from 99 to 71%, with free Cd(2+) increasing up to 6% and Cd-chlorocomplexes up to 23%. This work highlights the importance of soil organic reactive surfaces in reducing trace element bioavailability and phytoaccumulation. Chloride salinity increased Cd accumulation in leaves but not in fruit peel and

Soil salinity: Germination tolerance of alternative oilseed crops for soil health

USDA-ARS?s Scientific Manuscript database

World-wide, saline soils contribute to over US$27.3 billion in agricultural losses annually by reducing plant growth through osmotic imbalances and ion toxicity. Nearly 800,000 ha of salt affected land is located in the northern Great Plains. Limited information is available on the germination of al...

Impact assessment and recommendation of alternative conjunctive water use strategies for salt affected agricultural lands through a field scale decision support system - a case study.

PubMed

Kaur, Ravinder; Paul, Madhumita; Malik, Rashmi

2007-06-01

Conjunctive use of saline/non-saline irrigation waters is generally aimed at minimizing yield losses and enhancing flexibility of cropping, without much alteration in farming operations. Recommendation of location-specific suitable conjunctive water use plans requires assessment of their long-term impacts on soil salinization/sodification and crop yield reductions. This is conventionally achieved through long-term field experiments. However such impact evaluations are site specific, expensive and time consuming. Appropriate decision support systems (DSS) can be time-efficient and cost-effective means for such long-term impact evaluations. This study demonstrates the application of one such (indigenously developed) DSS for recommending best conjunctive water use plans for a, rice-wheat growing, salt affected farmer's field in Gurgaon district of Haryana (India). Before application, the DSS was extensively validated on several farmers and controlled experimental fields in Gurgaon and Karnal districts of Haryana (India). Validation of DSS showed its potential to give realistic estimates of root zone soil salinity (with R = 0.76-0.94; AMRE = 0.03-0.06; RMSPD = 0.51-0.90); sodicity (with R = 0.99; AMRE = 0.02; RMSPD = 0.84) and relative crop yield reductions (AMRE = 0.24), under existing (local) resource management practices. Long term (10 years) root zone salt build ups and associated rice/wheat crop yield reductions, in a salt affected farmer's field, under varied conjunctive water use scenarios were evaluated with the validated DSS. It was observed that long-term applications of canal (CW) and tube well (TW) waters in a cycle and in 1:1 mixed mode, during Kharif season, predicted higher average root zone salt reductions (2-9%) and lower rice crop yield reductions (4-5%) than the existing practice of 3-CW, 3-TW, 3-CW. Besides this, long-term application of 75% CW mixed with 25% TW, during Rabi season, predicted about 17% lower average root-zone salt reductions than

Detection of salts in soil using transversely excited atmospheric (TEA) carbon dioxide (CO2) laser-induced breakdown spectroscopy (LIBS) by the aid of a metal mesh

NASA Astrophysics Data System (ADS)

Idris, N.; Ramli, M.; Khumaeni, A.; Kurihara, K.

2018-04-01

In this work, a nickel metal mesh was used to allow a direct detection of salt in soil sample by LIBS utilizing unique characteristics of a TEA CO2. The metal mesh is placed in the front of the soil sample to prevent the soil sample from blowing off upon focusing the high pulsed laser beam irradiation. LIBS apparatus used in this work is a TEA CO2 laser operated at wavelength of 10.6 μm with pulse energy and duration of 3J and 200 ns, respectively. The laser beam was focused using a ZnSe lens (f = 200 mm) onto soil sample after passing through the metal mesh. The emission spectrum from the induced plasma was detected using an optical multichannel analyzer (OMA) system consisting of a 0.32-m-focal length spectrograph with a grating of 1200 graves/mm and a 1024-channel photodiode detector array with a micro-channel plate intensifier. The soil sample used is a standard soil and ordinary soil containing several salts such as Ca, Mg at high concentration. The LIBS experiment was carried out at high pressure surrounding gas of 1 atmosphere. It was observed that by the aid of the metal mesh, strong breakdown gas plasma can be produced just after TEA CO2 laser irradiation on soil sample without significant sample blowing off. It was found that emission lines from salts, Ca (Ca II 393. 3 nm, Ca II 396.3 nm, Ca I 422.5 nm), and also other salts including Mg and Na can clearly be detected with strong emission intensity and narrow spectral width. This result implies that a TEA CO2 LIBS assisted by the metal mesh (metal mesh method) can be used for direct analysis several salts such as Ca, Mg, and Na in soil sample.

Phosphate-Dependent Root System Architecture Responses to Salt Stress1[OPEN

PubMed Central

Sommerfeld, Hector Montero; ter Horst, Anneliek; Haring, Michel A.

2016-01-01

Nutrient availability and salinity of the soil affect the growth and development of plant roots. Here, we describe how inorganic phosphate (Pi) availability affects the root system architecture (RSA) of Arabidopsis (Arabidopsis thaliana) and how Pi levels modulate responses of the root to salt stress. Pi starvation reduced main root length and increased the number of lateral roots of Arabidopsis Columbia-0 seedlings. In combination with salt, low Pi dampened the inhibiting effect of mild salt stress (75 mm) on all measured RSA components. At higher salt concentrations, the Pi deprivation response prevailed over the salt stress only for lateral root elongation. The Pi deprivation response of lateral roots appeared to be oppositely affected by abscisic acid signaling compared with the salt stress response. Natural variation in the response to the combination treatment of salt and Pi starvation within 330 Arabidopsis accessions could be grouped into four response patterns. When exposed to double stress, in general, lateral roots prioritized responses to salt, while the effect on main root traits was additive. Interestingly, these patterns were not identical for all accessions studied, and multiple strategies to integrate the signals from Pi deprivation and salinity were identified. By genome-wide association mapping, 12 genomic loci were identified as putative factors integrating responses to salt stress and Pi starvation. From our experiments, we conclude that Pi starvation interferes with salt responses mainly at the level of lateral roots and that large natural variation exists in the available genetic repertoire of accessions to handle the combination of stresses. PMID:27208277

Dynamics of salt playa polygons

NASA Astrophysics Data System (ADS)

Goehring, L.; Fourrière, A.

2014-12-01

In natural salt playa or in evaporation pools for the salt extraction industry, one can sometimes see surprising regular structures formed by ridges of salt. These ridges connect together to form a self-organized network of polygons one to two meters in diameter, which we call salt polygons. Here we propose a mechanism based on porous media convection of salty water in soil to explain the formation and the scaling of the salt polygons. Surface evaporation causes a steady upward flow of salty water, which can cause precipitation near the surface. A vertical salt gradient then builds up in the porous soil, with heavy salt-saturated water lying over the less salty source water. This can drive convection when a threshold is reached, given by a critical Rayleigh number of about 7. We suggest that the salt polygons are the surface expression of the porous medium convection, with salt crystallizing along the positions of the convective downwellings. To study this instability directly, we developed a 2D analogue experiment using a Hele-Shaw cell filled with a porous medium saturated with a salt solution and heated from above. We perform a linear stability analysis of this system, and find that it is unstable to convection, with a most unstable wavelength that is set by a balance between salt diffusion and water evaporation. The Rayleigh number in our experiment is controlled by the particle size of our model soil, and the evaporation rate. We obtain results that scale with the observation of natural salt polygons. Using dye, we observe the convective movement of salty water and find downwelling convective plumes underneath the spots where surface salt ridges form, as shown in the attached figure.

Microbial Abundances in Salt Marsh Soils: A Molecular Approach for Small Spatial Scales

NASA Astrophysics Data System (ADS)

Granse, Dirk; Mueller, Peter; Weingartner, Magdalena; Hoth, Stefan; Jensen, Kai

2016-04-01

The rate of biological decomposition greatly determines the carbon sequestration capacity of salt marshes. Microorganisms are involved in the decomposition of biomass and the rate of decomposition is supposed to be related to microbial abundance. Recent studies quantified microbial abundance by means of quantitative polymerase chain reaction (QPCR), a method that also allows determining the microbial community structure by applying specific primers. The main microbial community structure can be determined by using primers specific for 16S rRNA (Bacteria) and 18S rRNA (Fungi) of the microbial DNA. However, the investigation of microbial abundance pattern at small spatial scales, such as locally varying abiotic conditions within a salt-marsh system, requires high accuracy in DNA extraction and QPCR methods. Furthermore, there is evidence that a single extraction may not be sufficient to reliably quantify rRNA gene copies. The aim of this study was to establish a suitable DNA extraction method and stable QPCR conditions for the measurement of microbial abundances in semi-terrestrial environments. DNA was extracted from two soil samples (top WE{5}{cm}) by using the PowerSoil DNA Extraction Kit (Mo Bio Laboratories, Inc., Carlsbad, CA) and applying a modified extraction protocol. The DNA extraction was conducted in four consecutive DNA extraction loops from three biological replicates per soil sample by reusing the PowerSoil bead tube. The number of Fungi and Bacteria rRNA gene copies of each DNA extraction loop and a pooled DNA solution (extraction loop 1 - 4) was measured by using the QPCR method with taxa specific primer pairs (Bacteria: B341F, B805R; Fungi: FR1, FF390). The DNA yield of the replicates varied at DNA extraction loop 1 between WE{25 and 85}{ng

Hydrogeochemical zonation in intertidal salt marsh sediments: evidence of positive plant-soil feedback?

NASA Astrophysics Data System (ADS)

Moffett, K. B.; Dittmar, J.; Seyfferth, A.; Fendorf, S.; Gorelick, S.

2012-12-01

Surface and subsurface environments are linked by the biogeochemical activity in near-surface sediment and by the hydrological fluxes that mobilize its reagents and products. A particularly dynamic and interesting setting to study near-surface hydrogeochemistry is the intertidal zone. Here, the very strong tidal hydraulic forcing is often thought to dominate water and solute transport. However, we demonstrated the importance of two additional subsurface drivers: groundwater flow and plant root water uptake. A high-resolution, coupled surface water-groundwater model of an intertidal salt marsh in San Francisco Bay, CA showed that these three drivers vary over different spatial scales: tidal flooding varies over 10's of meters; groundwater flow varies over meters, particularly within channel banks; and plant root water uptake varies in 3D at the sub-meter scale. Expanding on this third driver, we investigated whether the spatial variations in soil-water-plant hydraulic interactions that occur due to vegetation zonation also cause distinct geochemical zonation in salt marsh sediment pore waters. The existence of such geochemical zonation was verified and mapped by detailed field observations of the chemical composition of sediments, pore waters, surface waters, and vegetation. The field data and the coupled hydrologic model were then further analyzed to evaluate potential causal mechanisms for the geochemical zonation, including testing the hypothesis that the vegetation affects pore water geochemistry via a positive feedback beneficial to itself. If further supported by future studies, this geochemical feedback may complement known physical ecosystem engineering mechanisms to help stabilize and organize intertidal wetlands.

Water and salt dynamics and the hydraulic conductivity feedback: irreversible soil degradation and reclamation opportunities

NASA Astrophysics Data System (ADS)

Mau, Yair; Porporato, Amilcare

2017-04-01

We present a model for the dynamics of soil water, salt concentration and exchangeable sodium fraction in the root zone, driven by irrigation water of various qualities and stochastic rainfall. The main nonlinear feedback is the decrease in hydraulic conductivity for low salinity and/or high sodicity levels. The three variables have quite disparate characteristic time scales: soil water can vary two or three orders of magnitude faster than the exchangeable sodium fraction. In certain limiting cases in which the input of water is constant, the system can be simplified by eliminating the equation for soil water, allowing a full description of the dynamics in the two-dimensional salinity-sodicity phase space. We estimate soil structure degradation time scales for high sodium-adsorption-ratio irrigation water, and delineate the regions in the salinity-sodicity phase space where sodium-induced degradation is effectively irreversible. This apparent irreversibility is the result of relatively long evolution time scales with respect to human activity. When we take into account stochastic rainfall—and the accompanying wetting and drying cycles—the system produces a myriad of statistical steady states. This means that equal environmental conditions can produce different outcomes, accessible to each other only by large interventions, such as temporary changes in the quality of irrigation water or one-time amendment use. Our characterization of the dynamics of water and salt in the root zone, and how it depends on environmental parameters, offers us opportunities to control and reclaim degraded states making optimal resource use. We show an example of sodic soil reclamation through calcium-based fertigation, with minimal time (and applied water) expenditure.

Plant growth-promoting bacteria Bacillus amyloliquefaciens NBRISN13 modulates gene expression profile of leaf and rhizosphere community in rice during salt stress.

PubMed

Nautiyal, Chandra Shekhar; Srivastava, Suchi; Chauhan, Puneet Singh; Seem, Karishma; Mishra, Aradhana; Sopory, Sudhir Kumar

2013-05-01

Growth and productivity of rice and soil inhabiting microbial population is negatively affected by soil salinity. However, some salt resistant, rhizosphere competent bacteria improve plant health in saline stress. Present study evaluated the effect of salt tolerant Bacillus amyloliquefaciens NBRISN13 (SN13) inoculation on rice plants in hydroponic and soil conditions exposed to salinity. SN13 increased plant growth and salt tolerance (NaCl 200 mM) and expression of at least 14 genes under hydroponic and soil conditions in rice. Among these 14 genes 4 (NADP-Me2, EREBP, SOSI, BADH and SERK1) were up-regulated and 2 (GIG and SAPK4) repressed under salt stress in hydroponic condition. In greenhouse experiment, salt stress resulted in accumulation of MAPK5 and down-regulation of the remaining 13 transcripts was observed. SN13 treatment, with or without salt gave similar expression for all tested genes as compared to control. Salt stress caused changes in the microbial diversity of the rice rhizosphere and stimulated population of betaine-, sucrose-, trehalose-, and glutamine-utilizing bacteria in salt-treated rice rhizosphere (SN13 + salt). The observations imply that SN13 confers salt tolerance in rice by modulating differential transcription in a set of at least 14 genes. Stimulation of osmoprotectant utilizing microbial population as a mechanism of inducing salt tolerance in rice is reported for the first time in this study to the best of our knowledge. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

A new soil water and bulk eletrical conductivity sensor technology for irrigation and salinity management

USDA-ARS?s Scientific Manuscript database

Many soil water sensors, especially those based on electromagnetic (EM) properties of soils, have been shown to be unsuitable in salt-affected or clayey soils. Most available soil water content sensors are of this EM type, particularly the so-called capacitance sensors. They often over estimate and ...

Salt-stress-responsive chloroplast proteins in Brassica juncea genotypes with contrasting salt tolerance and their quantitative PCR analysis.

PubMed

Yousuf, Peerzada Yasir; Ahmad, Altaf; Aref, Ibrahim M; Ozturk, Munir; Hemant; Ganie, Arshid Hussain; Iqbal, Muhammad

2016-11-01

Brassica juncea is mainly cultivated in the arid and semi-arid regions of India where its production is significantly affected by soil salinity. Adequate knowledge of the mechanisms underlying the salt tolerance at sub-cellular levels must aid in developing the salt-tolerant plants. A proper functioning of chloroplasts under salinity conditions is highly desirable to maintain crop productivity. The adaptive molecular mechanisms offered by plants at the chloroplast level to cope with salinity stress must be a prime target in developing the salt-tolerant plants. In the present study, we have analyzed differential expression of chloroplast proteins in two Brassica juncea genotypes, Pusa Agrani (salt-sensitive) and CS-54 (salt-tolerant), under the effect of sodium chloride. The chloroplast proteins were isolated and resolved using 2DE, which facilitated identification and quantification of 12 proteins that differed in expression in the salt-tolerant and salt-sensitive genotypes. The identified proteins were related to a variety of chloroplast-associated molecular processes, including oxygen-evolving process, PS I and PS II functioning, Calvin cycle and redox homeostasis. Expression analysis of genes encoding differentially expressed proteins through real time PCR supported our findings with proteomic analysis. The study indicates that modulating the expression of chloroplast proteins associated with stabilization of photosystems and oxidative defence plays imperative roles in adaptation to salt stress.

Separation of Depleted Uranium From Soil

DTIC Science & Technology

2009-03-01

order to remove the metallic DU present in these soils. This procedure would re- duce the amount of time that metallic uranium could undergo corrosion ...slow corrosion is not sufficient to ignite the uranium . Unfired rod Weathered, unfired rod with yellow uranyl salt deposits Figure 1. Comparison...resulting in less downward movement. Interactions between uranium corrosion products and soil mineral and organic components can also affect

Geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples, and its possible relationship with the prevalence of enamel fluorosis in children in four municipalities of the department of Huila (Colombia).

PubMed

Martignon, Stefania; Opazo-Gutiérrez, Mario Omar; Velásquez-Riaño, Möritz; Orjuela-Osorio, Iván Rodrigo; Avila, Viviana; Martinez-Mier, Esperanza Angeles; González-Carrera, María Clara; Ruiz-Carrizosa, Jaime Alberto; Silva-Hermida, Blanca Cecilia

2017-06-01

Fluoride is an element that affects teeth and bone formation in animals and humans. Though the use of systemic fluoride is an evidence-based caries preventive measure, excessive ingestion can impair tooth development, mainly the mineralization of tooth enamel, leading to a condition known as enamel fluorosis. In this study, we investigated the geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples in four endemic enamel fluorosis sentinel municipalities of the department of Huila, Colombia (Pitalito, Altamira, El Agrado and Rivera), and its possible relationship with the prevalence of enamel fluorosis in children. The concentration of fluoride in drinking water, table salt, active sediment, rock, and soil was evaluated by means of an ion selective electrode and the geochemical analyses were performed using X-ray fluorescence. Geochemical analysis revealed fluoride concentrations under 15 mg/kg in active sediment, rock and soil samples, not indicative of a significant delivery to the watersheds studied. The concentration of fluoride in table salt was found to be under the inferior limit (less than 180 μg/g) established by the Colombian regulations. Likewise, exposure doses for fluoride water intake did not exceed the recommended total dose for all ages from 6 months. Although the evidence does not point out at rocks, soils, fluoride-bearing minerals, fluoridated salt and water, the hypothesis of these elements as responsible of the current prevalence of enamel fluorosis cannot be discarded since, aqueducts might have undergone significant changes overtime.

Soil aggregate stratification of nematodes and ammonia oxidizers affects nitrification in an acid soil.

PubMed

Jiang, Yuji; Jin, Chen; Sun, Bo

2014-10-01

Nitrification plays a central role in global nitrogen cycle, which is affected by interaction between soil microfauna and microorganisms. The impact of synchronized changes in nematodes and ammonia oxidizers within aggregate fractions on nitrification was investigated in an acid soil under 10-year manure application. Nematodes, ammonia oxidizers and potential nitrification activity (PNA) were examined in three soil aggregate fractions under four fertilization regimes. Pyrosequencing data revealed that the dominant bacterial amoA operational taxonomic units (OTUs) were related to Nitrosospira species, while archaeal OTUs were affiliated with Nitrososphaera and Nitrosotalea species. PNA was more strongly correlated with ammonia-oxidizing bacteria (AOB) abundance than ammonia-oxidizing archaea (AOA) abundance, although AOA were dominant in the acid soil. Plant parasites had a negative effect on AOB abundance; however, bacterivores stimulated AOB abundance and contributed more to PNA than plant parasites. Aggregate fractions exerted significant impacts on AOA abundance and AOB community composition. Total carbon content strongly affected the abundance and composition of AOA community, while soil pH primarily affected that of AOB community. Soil variables explained 62.7% and 58.1% variations, and nematode variables explained 11.7% and 19.5% variations in the AOA and AOB community composition respectively. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Green roof soil system affected by soil structural changes: A project initiation

NASA Astrophysics Data System (ADS)

Jelínková, Vladimíra; Dohnal, Michal; Šácha, Jan; Šebestová, Jana; Sněhota, Michal

2014-05-01

Anthropogenic soil systems and structures such as green roofs, permeable or grassed pavements comprise appreciable part of the urban watersheds and are considered to be beneficial regarding to numerous aspects (e.g. carbon dioxide cycle, microclimate, reducing solar absorbance and storm water). Expected performance of these systems is significantly affected by water and heat regimes that are primarily defined by technology and materials used for system construction, local climate condition, amount of precipitation, the orientation and type of the vegetation cover. The benefits and potencies of anthropogenic soil systems could be considerably threatened in case when exposed to structural changes of thin top soil layer in time. Extensive green roof together with experimental green roof segment was established and advanced automated monitoring system of micrometeorological variables was set-up at the experimental site of University Centre for Energy Efficient Buildings as an interdisciplinary research facility of the Czech Technical University in Prague. The key objectives of the project are (i) to characterize hydraulic and thermal properties of soil substrate studied, (ii) to establish seasonal dynamics of water and heat in selected soil systems from continuous monitoring of relevant variables, (iii) to detect structural changes with the use of X-ray Computed Tomography, (iv) to identify with the help of numerical modeling and acquired datasets how water and heat dynamics in anthropogenic soil systems are affected by soil structural changes. Achievements of the objectives will advance understanding of the anthropogenic soil systems behavior in conurbations with the temperate climate.

Genetic by environment interactions affect plant–soil linkages

PubMed Central

Pregitzer, Clara C; Bailey, Joseph K; Schweitzer, Jennifer A

2013-01-01

The role of plant intraspecific variation in plant–soil linkages is poorly understood, especially in the context of natural environmental variation, but has important implications in evolutionary ecology. We utilized three 18- to 21-year-old common gardens across an elevational gradient, planted with replicates of five Populus angustifolia genotypes each, to address the hypothesis that tree genotype (G), environment (E), and G × E interactions would affect soil carbon and nitrogen dynamics beneath individual trees. We found that soil nitrogen and carbon varied by over 50% and 62%, respectively, across all common garden environments. We found that plant leaf litter (but not root) traits vary by genotype and environment while soil nutrient pools demonstrated genotype, environment, and sometimes G × E interactions, while process rates (net N mineralization and net nitrification) demonstrated G × E interactions. Plasticity in tree growth and litter chemistry was significantly related to the variation in soil nutrient pools and processes across environments, reflecting tight plant–soil linkages. These data overall suggest that plant genetic variation can have differential affects on carbon storage and nitrogen cycling, with implications for understanding the role of genetic variation in plant–soil feedback as well as management plans for conservation and restoration of forest habitats with a changing climate. PMID:23919173

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

Characterization of soil salinization in typical estuarine area of the Jiaozhou Bay, China

NASA Astrophysics Data System (ADS)

Li, Qifei; Xi, Min; Wang, Qinggai; Kong, Fanlong; Li, Yue

2018-02-01

In this study, the characteristics of soil salinization and the effects of main land use/land cover and other factors in typical estuarine area of the Jiaozhou Bay are investigated. Soil samples were collected in the parallel coastal zone, vertical coastal zone and longitudinal profile depth in the area to determine the soil salt content. The correlation analysis and principal component analysis are used to address the general characteristics of soil salinization in the study area. In the horizontal direction, there are moderate salinization, severe salinization and saline soil state. The farther from the sea (within 1.1 km), the lower the soil salinization degree. In the direction of longitudinal profile depth, there are severe salinization and saline soil state, and the soil salt content is accumulated in the surface and bottom. The Na+ and Cl- are the dominant cation and anion, respectively, the distributions of which are consistent with that of salt content. All the salinization indexes, except for soil pH, are of moderate/strong variability. The invasion of Spartina alterniflora results in the increase of soil salt content and salinization degree, the effects of which are mainly determined by the physiological characteristics and the growth years. The degree of soil salinization increased significantly in the aquaculture ponds, which is mainly caused by the use of chemicals. The correlation between soil salt content and Na+, Cl- is particularly significant. From the results of principal component analysis, Na+, Cl-, Ca2+, Mg2+ and SO42- could be used as main diagnostic factors for salinization in typical estuarine area of the Jiaozhou Bay. The effects of NaCl and sulfate on salt content further affect the degree of salinization in the estuarine area.

Soil salination indicators

USDA-ARS?s Scientific Manuscript database

Salts are naturally present in soils, and many salt elements are essential nutrients for plants. The most common soluble salts in soil include major cations of sodium (Na+), magnesium (Mg2+), calcium (Ca2+), potassium (K+), and anions of chloride (Cl-), sulfate (SO42-), bicarbonate (HCO3-) and carbo...

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. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Soil salinization in different natural zones of intermontane depressions in Tuva

NASA Astrophysics Data System (ADS)

Chernousenko, G. I.; Kurbatskaya, S. S.

2017-11-01

Soil salinization features in semidesert, dry steppe, and chernozemic steppe zones within intermontane depressions in the central part of the Tuva Republic are discussed. Chernozems, chestnut soils, and brown desert-steppe soils of these zones are usually nonsaline. However, salinization of these zonal soils is possible in the case of the presence of salt-bearing parent materials (usually, the derivatives of Devonian deposits). In different natural zones of the intermontane depressions, salt-affected soils are mainly allocated to endorheic lake basins, where they are formed in places of discharge of mineral groundwater, and to river valleys. The composition and content of salts in the natural waters are dictated by the local hydrogeological conditions. The total content of dissolved solids in lake water varies from 1 to 370 g/L; the water is usually of the sulfate-chloride or chloride-sulfate salinity type; in some cases, soda-sulfate water is present. Soil salinity around the lakes is usually of the chloride-sulfate-sodium type; gypsum is often present in the profiles. Chloride salinization rarely predominates in this part of Tuva, because chlorides are easily leached off from the mainly coarse-textured soils. In some cases, the predominance of magnesium over sodium is observed in the composition of dissolved salts, which may be indicative of the cryogenic transformation of soil salts. Soda-saline soils are present in all the considered natural zones on minor areas. It is hardly possible to make unambiguous statements about the dominance of the particular type of salinity in the given natural zones. Zonal salinity patterns are weakly expressed in salinization of hydromorphic soils. However, a tendency for more frequent occurrence of soda-saline soils in steppe landscapes and chloride-sulfate salinization (often, with participation of gypsum) in the dry steppe and semidesert landscapes is observed.

[Soils salinity content of greenhouse in Shanghai suburb].

PubMed

Yao, Chun-Xia; Chen, Zhen-Lou; Xu, Shi-Yuan

2007-06-01

Salinity content and characteristic of farmland soil in Shanghai suburb was studied. Result indicates that soils in greenhouse in Shanghai suburb are partially salted. Soils of suburb where melons or vegetables grow in Shanghai city, 88.52% soil is non-salted while 10.37% mildly salted, 0.74% obviously salted and 0.37% badly salted. Anions component of salt salinity in soil are mainly SO4(2-), Cl-, NO3(-) and cations component are mainly Ca2+, Na+, Mg2+, K+. These ions are mostly from fertilizer auxiliary component or fertilizer transformation component besides some original deposition in soil. The formation of soil secondary salted in greenhouse cultivation in suburbs of Shanghai has a close relationship with improper fertilization or employing too much fertilizer. Soil salinity is different with different cultivation mode and utilization time. From high to low, sequence of soil salinity content in 0 - 20 cm cultivation layer of different crop mode is greenhouse vegetable soil, melon soil, vegetable melon rotation soil and hypaethral vegetable soil respectively. In the same region, salinity in greenhouse soil continually increases and accumulates from underlayer to surface along with more utilization years.

[Investigation and canonical correspondence analysis of salinity contents in secondary salinization greenhouse soils in Shanghai suburb].

PubMed

Tang, Dong; Mao, Liang; Zhi, Yue-e; Zhang, Jin-Zhong; Zhou, Pei; Chai, Xiao-Tong

2014-12-01

The salinity characteristics of greenhouse soils with cropping obstacles in Shanghai suburb were investigated and analyzed. The salinity contents of the salinization greenhouse soils showed a trend of first increasing and then decreasing with the increasing cropping duration. The salinized soils mainly included slightly salted, mildly salted and salted soils, which accounted for 17.39%, 56.52% and 13.04%, respectively. Among them, the degree of salinity in greenhouse soil planted with asparagus in Chongming County was the highest. Among the salt ions in greenhouse soils, the cations were mainly Ca2+ and Na+, while the anions were mainly NO3- and SO4(2-). The degree of salinity was mainly influenced by fertilization mode, cropping duration, crop type and management level, which led to the great variation in the salinity contents and salt ions. Canonical correspondence analysis found that the contents of Ca2+, Mg2+ and NO3- in greenhouse soils were greatly affected by cropping duration, and the degree of salinity would be enhanced and attenuated with long-term application of single fertilizer and mixed application of chemical fertilizer and organic manure, respectively. The greenhouse soils in Shanghai suburb could be classified as four patterns influenced by the relationship between salinity ions and samples, and the most soils were influenced by Ca2+, Mg2+, NO3- and Cl-, which required to be primarily controlled.

High-resolution mapping and spatial variability of soil organic carbon storage of permafrost-affected soils

NASA Astrophysics Data System (ADS)

Siewert, Matthias; Hugelius, Gustaf

2017-04-01

Permafrost-affected soils store large amounts of soil organic carbon (SOC). Mapping of this SOC provides a first order spatial input variable for research that relates carbon stored in permafrost regions to carbon cycle dynamics. High-resolution satellite imagery is becoming increasingly available even in circum-polar regions. The presented research highlights findings of high-resolution mapping efforts of SOC from five study areas in the northern circum-polar permafrost region. These study areas are located in Siberia (Kytalyk, Spasskaya Pad /Neleger, Lena delta), Northern Sweden (Abisko) and Northwestern Canada (Herschel Island). Our high spatial resolution analyses show how geomorphology has a strong influence on the distribution of SOC. This is organized at different spatial scales. Periglacial landforms and processes dictate local scale SOC distribution due to patterned ground. Such landforms are non-sorted circles and ice-wedge polygons of different age and scale. Palsas and peat plateaus are formed and can cover larger areas in Sub-Arctic environments. Study areas that have not been affected by Pleistocene glaciation feature ice-rich Yedoma sediments that dominate the local relief through thermokarst formation and create landscape scale macro environments that dictate the distribution of SOC. A general trend indicates higher SOC storage in Arctic tundra soils compared to forested Boreal or Sub-Arctic taiga soils. Yet, due to the shallower active layer depth in the Arctic, much of the SOC may be permanently frozen and thus not be available to ecosystem processes. Significantly more SOC is stored in soils compared to vegetation, indicating that vegetation growth and incorporation of the carbon into the plant phytomass alone will not be able to offset SOC released from permafrost. This contribution also addresses advances in thematic mapping methods and digital soil mapping of SOC in permafrost terrain. In particular machine-learning methods, such as support

Effects, tolerance mechanisms and management of salt stress in grain legumes.

PubMed

Farooq, Muhammad; Gogoi, Nirmali; Hussain, Mubshar; Barthakur, Sharmistha; Paul, Sreyashi; Bharadwaj, Nandita; Migdadi, Hussein M; Alghamdi, Salem S; Siddique, Kadambot H M

2017-09-01

transgenics and crop management strategies may enhance salt tolerance and yield in grain legumes on salt-affected soils. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Salt tolerant plants increase nitrogen removal from biofiltration systems affected by saline stormwater.

PubMed

Szota, Christopher; Farrell, Claire; Livesley, Stephen J; Fletcher, Tim D

2015-10-15

Biofiltration systems are used in urban areas to reduce the concentration and load of nutrient pollutants and heavy metals entering waterways through stormwater runoff. Biofilters can, however be exposed to salt water, through intrusion of seawater in coastal areas which could decrease their ability to intercept and retain pollutants. We measured the effect of adding saline stormwater on pollutant removal by six monocotyledonous species with different levels of salt-tolerance. Carex appressa, Carex bichenoviana, Ficinia nodosa, Gahnia filum, Juncus kraussii and Juncus usitatus were exposed to six concentrations of saline stormwater, equivalent to electrical conductivity readings of: 0.09, 2.3, 5.5, 10.4, 20.0 and 37.6 mS cm(-1). Salt-sensitive species: C. appressa, C. bichenoviana and J. usitatus did not survive ≥10.4 mS cm(-1), removing their ability to take up nitrogen (N). Salt-tolerant species, such as F. nodosa and J. kraussii, maintained N-removal even at the highest salt concentration. However, their levels of water stress and stomatal conductance suggest that N-removal would not be sustained at concentrations ≥10.4 mS cm(-1). Increasing salt concentration indirectly increased phosphorus (P) removal, by converting dissolved forms of P to particulate forms which were retained by filter media. Salt concentrations ≥10 mS cm(-1) also reduced removal efficiency of zinc, manganese and cadmium, but increased removal of iron and lead, regardless of plant species. Our results suggest that biofiltration systems exposed to saline stormwater ≤10 mS cm(-1) can only maintain N-removal when planted with salt-tolerant species, while P removal and immobilisation of heavy metals is less affected by species selection. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low-Concentration Kinetics of Atmospheric CH4 Oxidation in Soil and Mechanism of NH4+ Inhibition

PubMed Central

Gulledge, Jay; Schimel, Joshua P.

1998-01-01

NH4+ inhibition kinetics for CH4 oxidation were examined at near-atmospheric CH4 concentrations in three upland forest soils. Whether NH4+-independent salt effects could be neutralized by adding nonammoniacal salts to control samples in lieu of deionized water was also investigated. Because the levels of exchangeable endogenous NH4+ were very low in the three soils, desorption of endogenous NH4+ was not a significant factor in this study. The Km(app) values for water-treated controls were 9.8, 22, and 57 nM for temperate pine, temperate hardwood, and birch taiga soils, respectively. At CH4 concentrations of ≤15 μl liter−1, oxidation followed first-order kinetics in the fine-textured taiga soil, whereas the coarse-textured temperate soils exhibited Michaelis-Menten kinetics. Compared to water controls, the Km(app) values in the temperate soils increased in the presence of NH4+ salts, whereas the Vmax(app) values decreased substantially, indicating that there was a mixture of competitive and noncompetitive inhibition mechanisms for whole NH4+ salts. Compared to the corresponding K+ salt controls, the Km(app) values for NH4+ salts increased substantially, whereas the Vmax(app) values remained virtually unchanged, indicating that NH4+ acted by competitive inhibition. Nonammoniacal salts caused inhibition to increase with increasing CH4 concentrations in all three soils. In the birch taiga soil, this trend occurred with both NH4+ and K+ salts, and the slope of the increase was not affected by the addition of NH4+. Hence, the increase in inhibition resulted from an NH4+-independent mechanism. These results show that NH4+ inhibition of atmospheric CH4 oxidation resulted from enzymatic substrate competition and that additional inhibition that was not competitive resulted from a general salt effect that was independent of NH4+. PMID:9797279

Pesticide interactions with soils affected by olive oil mill wastewater

NASA Astrophysics Data System (ADS)

Keren, Yonatan; Bukhanovsky, Nadezhda; Borisover, Mikhail

2013-04-01

Soil pesticide sorption is well known to affect the fate of pesticides, their bioavailability and the potential to contaminate air and water. Soil - pesticide interactions may be strongly influenced by soil organic matter (SOM) and organic matter (OM)-rich soil amendments. One special OM source in soils is related to olive oil production residues that may include both solid and liquid wastes. In the Mediterranean area, the olive oil production is considered as an important field in the agricultural sector. Due to the significant rise in olive oil production, the amount of wastes is growing respectively. Olive oil mill waste water (OMWW) is the liquid byproduct in the so-called "three phase" technological process. Features of OMWW include the high content of fatty aliphatic components and polyphenols and their often-considered toxicity. One way of OMWW disposal is the land spreading, e.g., in olive orchards. The land application of OMWW (either controlled or not) is supposed to affect the multiple soil properties, including hydrophobicity and the potential of soils to interact with pesticides. Therefore, there is both basic and applied interest in elucidating the interactions between organic compounds and soils affected by OMWW. However, little is known about the impact of OMWW - soil interactions on sorption of organic compounds, and specifically, on sorption of agrochemicals. This paper reports an experimental study of sorption interactions of a series of organic compounds including widely used herbicides such as diuron and simazine, in a range of soils that were affected by OMWW (i) historically or (ii) in the controlled land disposal experiments. It is demonstrated that there is a distinct increase in apparent sorption of organic chemicals in soils affected by OMWW. In selected systems, this increase may be explained by increase in SOM content. However, the SOM quality places a role: the rise in organic compound - soil interactions may both exceed the SOM

Salt stress-induced changes in antioxidative defense system and proteome profiles of salt-tolerant and sensitive Frankia strains.

PubMed

Srivastava, Amrita; Singh, Anumeha; Singh, Satya S; Mishra, Arun K

2017-04-16

An appreciation of comparative microbial survival is most easily done while evaluating their adaptive strategies during stress. In the present experiment, antioxidative and whole cell proteome variations based on spectrophotometric analysis and SDS-PAGE and 2-dimensional gel electrophoresis have been analysed among salt-tolerant and salt-sensitive Frankia strains. This is the first report of proteomic basis underlying salt tolerance in these newly isolated Frankia strains from Hippophae salicifolia D. Don. Salt-tolerant strain HsIi10 shows higher increment in the contents of superoxide dismutase, catalase and ascorbate peroxidase as compared to salt-sensitive strain HsIi8. Differential 2-DGE profile has revealed differential profiles for salt-tolerant and salt-sensitive strains. Proteomic confirmation of salt tolerance in the strains with inbuilt efficiency of thriving in nitrogen-deficient locales is a definite advantage for these microbes. This would be equally beneficial for improvement of soil nitrogen status. Efficient protein regulation in HsIi10 suggests further exploration for its potential use as biofertilizer in saline soils.

Cadmium hampers salt tolerance of Sesuvium portulacastrum.

PubMed

Wali, Mariem; Martos, Soledad; Pérez-Martín, Laura; Abdelly, Chedly; Ghnaya, Tahar; Poschenrieder, Charlotte; Gunsé, Benet

2017-06-01

It is well known that salinity reduces cadmium toxicity in halophytes. However, the possible interference of Cd with the mechanisms of salt tolerance is poorly explored. The aim of this study was to see whether Cd affects salt tolerance mechanisms in the halophyte Sesuvium portulacastrum. S. portulacastrum plants obtained from cuttings were grown in hydroponics for 3 weeks and then exposed to low (0.09 mM) or moderate (200 mM) NaCl concentrations, alone or in combination with 25 μM CdCl 2 . Microscopy observation revealed two strategies of salt tolerance: euhalophytism and secretion of salt by bladder cells. Cadmium exposure hardly influenced the total leaf Na + concentrations. However, Cd supply delayed the salt-induced upregulation of AHA1 (plasma membrane H + -ATPase 1) and SOS1 (plasma membrane Na + transporter "Salt Overly Sensitive 1"), genes that are essential for salt tolerance. Moreover, Cd induced the activation of BADH, coding for betaine aldehyde dehydrogenase, indicating enhanced osmotic stress due to Cd. Sodium-green fluorescence in protoplasts from plants grown with low or high NaCl, alone or in combination with Cd, revealed higher Na + concentrations in the cytoplasm of Cd-exposed plants. Taken together the results indicate interference of Cd with salt tolerance mechanisms in S. portulacastrum. This may have consequences for the efficient use of halophytes in phytoremediation of Cd-contaminated saline soils. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Analyses of the soil surface dynamic of South African Kalahari salt pans based on hyperspectral and multitemporal data

NASA Astrophysics Data System (ADS)

Milewski, Robert; Chabrillat, Sabine; Behling, Robert; Mielke, Christian; Schleicher, Anja Maria; Guanter, Luis

2016-04-01

The consequences of climate change represent a major threat to sustainable development and growth in Southern Africa. Understanding the impact on the geo- and biosphere is therefore of great importance in this particular region. In this context the Kalahari salt pans (also known as playas or sabkhas) and their peripheral saline and alkaline habitats are an ecosystem of major interest. They are very sensitive to environmental conditions, and as thus hydrological, mineralogical and ecological responses to climatic variations can be analysed. Up to now the soil composition of salt pans in this area have been only assessed mono-temporally and on a coarse regional scale. Furthermore, the dynamic of the salt pans, especially the formation of evaporites, is still uncertain and poorly understood. High spectral resolution remote sensing can estimate evaporite content and mineralogy of soils based on the analyses of the surface reflectance properties within the Visible-Near InfraRed (VNIR 400-1000 nm) and Short-Wave InfraRed (SWIR 1000-2500 nm) regions. In these wavelength regions major chemical components of the soil interact with the electromagnetic radiation and produce characteristic absorption features that can be used to derive the properties of interest. Although such techniques are well established for the laboratory and field scale, the potential of current (Hyperion) and upcoming spaceborne sensors such as EnMAP for quantitative mineralogical and salt spectral mapping is still to be demonstrated. Combined with hyperspectral methods, multitemporal remote sensing techniques allow us to derive the recent dynamic of these salt pans and link the mineralogical analysis of the pan surface to major physical processes in these dryland environments. In this study we focus on the analyses of the Namibian Omongwa salt pans based on satellite hyperspectral imagery and multispectral time-series data. First, a change detection analysis is applied using the Iterative

In situ detection of microbial respiration in soils and salt flats. [Nevada desert

NASA Technical Reports Server (NTRS)

Tew, R. W.

1973-01-01

Increase in CO2 partial pressures over a desert soil treated with casamino-acids glucose solution correlated with bacterial growth. Few or no increases in numbers of bacteria or CO2 concentrations were noted in similar plots treated with water only or receiving no treatment. Growth in the soil appeared to be severely nutrient limited during the 10 day experiment. Especially rapid growth took place between the third and fifth day, when temperatures ranged from 0 deg. (night) to a maximum of 17.4 deg. (day). Under the conditions of the experiment, intermittent CO2 assay was an insensitive indicator of growth, possibly because of restiction of gas escape by the desert pavement or solution, exchange, or precipitation of carbonate, but more likely because of inefficient sealing of hoods to and below the soil surface. CO2 assay was unable to detect microbial successions. The unpredictable course of these successions, plus unpredictable relative retentions mitigates against assay of organic gases as reliable in situ detection of microbial activity, except perhaps in very alkaline environments such as Owens Lake salts.

Interpretation of in situ tests as affected by soil suction.

DOT National Transportation Integrated Search

2013-07-01

Soil moisture conditions are subject to change depending on the season in which they are tested. In : unsaturated soils the moisture at which a soil is tested can directly affect strength and stiffness of the : material. In situ testing is commonly u...

The Distribution of Road Salt in Private Drinking Water Wells in a Southeastern New York Suburban Township.

PubMed

Kelly, Victoria R; Cunningham, Mary Ann; Curri, Neil; Findlay, Stuart E; Carroll, Sean M

2018-05-01

We used a GIS analysis of sodium and chloride concentrations in private water wells in a southeastern New York township to describe the pattern of distribution of road salt in aquifers tapped for drinking water. The primary source of road salt was sodium chloride, and sodium and chloride concentrations were significantly correlated ( = 0.80, < 0.01). Chloride concentrations in wells increased as the percentage of impervious surface cover (ISC) within a 250-m radius around wells increased ( = 0.87, < 0.01) and declined with increasing distance to the nearest road ( = 0.76, < 0.01). Wells that were located lower in elevation than the nearest road had higher concentrations of chloride than wells that were higher than the nearest road, but this occurred only when the nearest road was >30 m from the wells ( < 0.01). Chloride concentrations were not affected by well depth or adjacent road type (major or minor roads). Surface geology and hydrologic soil class had significant effects ( < 0.01) on chloride concentrations in wells, with porous surface geology types and well-drained soils having higher concentrations; these effects may be confounded by the fact that ISC was more likely to occur on these permeable surface geology and soil types. Hot and cold spot analysis revealed substantial unevenness in chloride concentrations. Results for sodium were similar to those for chloride. Overall, these results indicate that road salt contamination of groundwater is unevenly distributed and is affected by landscape factors that can be used to guide well testing and best management practices of deicing salt distribution. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Do dry roasting, lightly salting nuts affect their cardioprotective properties and acceptability?

PubMed

Tey, Siew Ling; Robinson, Terryn; Gray, Andrew R; Chisholm, Alexandra W; Brown, Rachel Clare

2017-04-01

Previous studies have reported improvements in cardiovascular disease (CVD) risk factors with the consumption of raw nuts. However, around one-third of nuts consumed are roasted and salted. Thus, it is important to determine whether roasting and salting nuts affect the health benefits observed with raw nuts. This study aimed to compare the effects of consuming two different forms of hazelnuts on cardiovascular risk factors and acceptance. Using a randomised crossover design, 72 participants were asked to consume 30 g/day of either raw or dry roasted, lightly salted hazelnuts for 28 days each. CVD risk factors were measured at the beginning and end of each treatment period. "Desire to consume" and "overall liking" for both forms of hazelnuts were assessed daily using a 150-mm visual analogue scale. Body composition, blood pressure, plasma total and low-density lipoprotein-cholesterol, apolipoprotein A1 and B100, glucose and α-tocopherol concentrations did not differ between forms of hazelnuts (all P ≥ 0.054). High-density lipoprotein (HDL)-cholesterol (P = 0.037) and triacylglycerol (P < 0.001) concentrations were significantly lower following the consumption of dry roasted, lightly salted hazelnuts when compared to the raw hazelnuts. Compared with baseline, consuming both forms of hazelnuts significantly improved HDL-cholesterol and apolipoprotein A1 concentrations, total-C/HDL-C ratio, and systolic blood pressure without significantly changing body composition. Acceptance ratings did not differ between forms of hazelnuts and remained high throughout the study. Dry roasting and lightly salting nuts do not appear to negate the cardioprotective effects observed with raw nut consumption, and both forms of nuts are resistant to monotony. Public health messages could be extended to include dry roasted and lightly salted nuts as part of a heart healthy diet.

[Phosphorus availability in cropland soils of China and related affecting factors].

PubMed

Wang, Yong-Zhuang; Chen, Xin; Shi, Yi

2013-01-01

Soil phosphorus (P) availability directly determines cropland productivity. Based on the long-term fertilization experiments in different climatic zones of China, this paper summarized the P content, its availability, and the factors affecting the P transformation in China cropland soils. The total and available P contents in different types of China cropland soils were 0.31-1.72 g x kg(-1) and 0.1-228.8 mg x kg(-1), respectively. Soil parent material, soil physical and chemical prosperities, and fertilization practices were the main factors affecting the soil P availability. It was suggested that more attentions should be paid on the mixed application of organic manure and chemical fertilizers to improve the P availability of cropland soils and on the potential environmental impacts of this fertilization.

Salting the landscapes in Transbaikalia: natural and technogenic factors

NASA Astrophysics Data System (ADS)

Peryazeva, E. G.; Plyusnin, A. M.; Chinavlev, A. M.

2010-05-01

Salting the soils, surface and subsurface waters is widespread in Transbaikalia. Hearths of salting occur within intermountain depressions of the Mesozoic and Cenozoic age both in the steppe arid and forest humid landscapes. Total water mineralization reaches 80 g/dm3 in lakes and 4-5 g/dm3 in subsurface waters. The waters belong to hydrocarbonate sodium and sulfate sodium types by chemical composition. The soda type of waters is widely spread through the whole area. Sulfate waters are found in several hearths of salting. Deposition of salts takes place in some lakes. Mirabilite and soda depositions are most commonly observed in muds of salt lakes. Deposition of salts occurs both as a result of evaporative concentrating and during freezing out the solvent. In the winter period, efflorescences of salts, where decawater soda is main mineral, are observed on ice surface. Solonchaks are spread in areas of shallow ground waters (1-2m). Soil salting is most intense in the lower parts of depressions, where surface of ground waters is at depth 0.5-1.0m. In soil cover of solonchaks, salt horizon is of various thicknesses, and it has various morphological forms of occurrence, i.e. as thick deposits of salts on soil surface and salting the surficial horizons. The soil has low alkaline reaction of medium and is characterized by high content of exchangeable bases with significant content of exchangeable sodium in the absorbing complex. Total amount of salts varies from 0.7 to 1.3%. Their maximal quantity (3.1%) is confined to the surficial layer. Sulfate-sodium type of salting is noted in the solonchak upper horizons and sulfate-magnesium-calcium one in the lower ones (Ubugunov et al, 2009). Formation of salting hearths is associated with natural and technogenic conditions. The Mesozoic depressions of Transbaikalia are characterized by intense volcanism. Covers of alkaline and moderately alkaline basalts that are enriched in potassium, sodium, carbon dioxide, fluorine, chlorine

Updates on Water Use of Pistachio Orchards Grown in the San Joaquin Valley of California on Saline Soils

NASA Astrophysics Data System (ADS)

Zaccaria, Daniele; Marino, Giulia; Whiting, Michael; Sanden, Blake; Ferguson, Louise; Lampinen, Bruce; Kent, Eric; Snyder, Richard; Grattan, Stephen; Little, Cayle

2017-04-01

Pistachio acreage is rapidly expanding in California thanks to its economic profitability and capacity to grow and produce in salt-affected soils. Our team at University of California is updating information on actual water use (ET) of mature pistachio orchards grown on saline soils under micro-irrigation methods. Actual Evapotranspiration (ETa) and Crop Coefficients (Ka) were determined for the 2015 and 2016 crop seasons on four pistachio orchards grown in the San Joaquin Valley (SJV) on grounds with increasing levels of soil-water salinity, using the residual of energy balance method with a combination of eddy covariance and surface renewal equipment. Tree canopy cover, light interception, and plant water status across the orchards were also measured and evaluated. Our preliminary results show that salinity strongly affects the tree water use, resulting in 10-30% less ET for medium to high salt-affected soils. Salinity also showed a strong effect on tree water status and light interception, as suggested by values of the Midday Stem Water Potential (ΨSWP) around 10 to 15-bar lower in salt-affected than in the control orchard, and by the intercepted Photosynthetic Active Radiation (PAR) decreasing from 75% in the control orchard to 25% in the severely salt affected grounds. The crop coefficient values we observed in this study are lower than those commonly used for irrigation scheduling in the SJV, suggesting that pistachio growers could better tailor irrigation management to the actual site-specific orchard conditions (e.g. canopy features and soil-water salinity) if they are provided updated information. Improved irrigation practices could likely lead to significant water savings and thus improve the resource-efficiency and competitiveness of pistachio production in the SJV. Keywords: Pistacia vera L., salinity, stem water potential, surface renewal, canopy cover.

Effects of imidacloprid on soil microbial communities in different saline soils.

PubMed

Zhang, Qingming; Xue, Changhui; Wang, Caixia

2015-12-01

The effects of imidacloprid in the soil environment are a worldwide concern. However, the impact of imidacloprid on soil microorganisms under salt stress is almost unknown. Therefore, an indoor incubation test was performed, and the denaturing gradient gel electrophoresis (DGGE) approach was used to determine the response of different saline soil bacterial and fungal community structures to the presence of imidacloprid (0.4, 2, 10 mg kg(-1)). The results showed that the soil bacterial diversity slightly declined with increasing imidacloprid concentration in soils with low salinity. In moderately saline soils, a new band in the DGGE profile suggested that imidacloprid could improve the soil bacterial diversity to some degree. An analysis of variance indicated that the measured soil bacterial diversity parameters were significantly affected by dose and incubation time. Compared with the control, the soil fungal community structure showed no obvious changes in low and moderately saline soils treated with imidacloprid. The results of these observations provide a basic understanding of the potential ecological effects of imidacloprid on different microorganisms in saline soils.

Effects of middle-term land reclamation on nickel soil-water interaction: a case study from reclaimed salt marshes of Po River Delta, Italy.

PubMed

Di Giuseppe, Dario; Melchiorre, Massimiliano; Faccini, Barbara; Ferretti, Giacomo; Coltorti, Massimo

2017-09-26

Reclaimed salt marshes are fragile environments where water salinization and accumulation of heavy metals can easily occur. This type of environment constitutes a large part of the Po River Delta (Italy), where intensive agricultural activities take place. Given the higher Ni background of Po River Delta soils and its water-soluble nature, the main aim of this contribution is to understand if reclamation can influence the Ni behavior over time. In this study, we investigated the geochemical features of 40 soils sampled in two different localities from the Po River Delta with different reclamation ages. Samples of salt marsh soils reclaimed in 1964 were taken from Valle del Mezzano while soils reclaimed in 1872 were taken nearby Codigoro town. Batch solubility tests and consecutive determination of Ni in pore-water were compared to bulk physicochemical compositions of soils. Bulk Ni content of the studied soils is naturally high, since these soils originated from Po River sediments derived from the erosion of ultramafic rocks. Moreover, it seems that Ni concentration increases during soil evolution, being probably related to the degradation of serpentine. Instead, the water-soluble Ni measured in the leaching tests is greater in soils recently reclaimed compared to the oldest soils. Soil properties of two soil profiles from a reclaimed wetland area were examined to determine soil evolution over one century. Following reclamation, pedogenic processes of the superficial horizons resulted in organic matter mineralization, pH buffer, and a decrease of Ni water solubility from recently to evolved reclaimed soil.

Molecular breeding in Brassica for salt tolerance: importance of microsatellite (SSR) markers for molecular breeding in Brassica.

PubMed

Kumar, Manu; Choi, Ju-Young; Kumari, Nisha; Pareek, Ashwani; Kim, Seong-Ryong

2015-01-01

Salinity is one of the important abiotic factors for any crop management in irrigated as well as rainfed areas, which leads to poor harvests. This yield reduction in salt affected soils can be overcome by improving salt tolerance in crops or by soil reclamation. Salty soils can be reclaimed by leaching the salt or by cultivation of salt tolerance crops. Salt tolerance is a quantitative trait controlled by several genes. Poor knowledge about mechanism of its inheritance makes slow progress in its introgression into target crops. Brassica is known to be a good reclamation crop. Inter and intra specific variation within Brassica species shows potential of molecular breeding to raise salinity tolerant genotypes. Among the various molecular markers, SSR markers are getting high attention, since they are randomly sparsed, highly variable and show co-dominant inheritance. Furthermore, as sequencing techniques are improving and softwares to find SSR markers are being developed, SSR markers technology is also evolving rapidly. Comparative SSR marker studies targeting Arabidopsis thaliana and Brassica species which lie in the same family will further aid in studying the salt tolerance related QTLs and subsequent identification of the "candidate genes" and finding out the origin of important QTLs. Although, there are a few reports on molecular breeding for improving salt tolerance using molecular markers in Brassica species, usage of SSR markers has a big potential to improve salt tolerance in Brassica crops. In order to obtain best harvests, role of SSR marker driven breeding approaches play important role and it has been discussed in this review especially for the introgression of salt tolerance traits in crops.

Molecular breeding in Brassica for salt tolerance: importance of microsatellite (SSR) markers for molecular breeding in Brassica

PubMed Central

Kumar, Manu; Choi, Ju-Young; Kumari, Nisha; Pareek, Ashwani; Kim, Seong-Ryong

2015-01-01

Salinity is one of the important abiotic factors for any crop management in irrigated as well as rainfed areas, which leads to poor harvests. This yield reduction in salt affected soils can be overcome by improving salt tolerance in crops or by soil reclamation. Salty soils can be reclaimed by leaching the salt or by cultivation of salt tolerance crops. Salt tolerance is a quantitative trait controlled by several genes. Poor knowledge about mechanism of its inheritance makes slow progress in its introgression into target crops. Brassica is known to be a good reclamation crop. Inter and intra specific variation within Brassica species shows potential of molecular breeding to raise salinity tolerant genotypes. Among the various molecular markers, SSR markers are getting high attention, since they are randomly sparsed, highly variable and show co-dominant inheritance. Furthermore, as sequencing techniques are improving and softwares to find SSR markers are being developed, SSR markers technology is also evolving rapidly. Comparative SSR marker studies targeting Arabidopsis thaliana and Brassica species which lie in the same family will further aid in studying the salt tolerance related QTLs and subsequent identification of the “candidate genes” and finding out the origin of important QTLs. Although, there are a few reports on molecular breeding for improving salt tolerance using molecular markers in Brassica species, usage of SSR markers has a big potential to improve salt tolerance in Brassica crops. In order to obtain best harvests, role of SSR marker driven breeding approaches play important role and it has been discussed in this review especially for the introgression of salt tolerance traits in crops. PMID:26388887

The nature and classification of Australian soils affected by sodium

NASA Astrophysics Data System (ADS)

Murphy, Brian; Greene, Richard; Harms, Ben

2017-04-01

Large areas of Australia are affected by the processes of salinity and sodicity and they are important processes to understand as they can result in the degradation of agricultural lands used for both intensive cropping and extensive grazing practices. Sodic soils are defined as those having ESP of at least 6% in Australia. Northcote and Skene (1972) estimated that of Australia's total area of 770 M ha, 39 M ha was affected by salinity and 193-257 M ha by sodicity. However, in a more recent publication, Rengasamy (2006), quoted the areas of saline and sodic soils as 66 M ha and 340 M ha respectively. The soils affected by sodium in Australia include a large group of contrasting soils (Northcote and Skene 1972). Based on the Australian soil classification, included are: • Alkaline strongly sodic to sodic clay soils with uniform texture profiles - largely Vertosols 666 400 km2 • Alkaline strongly sodic to sodic coarse and medium textured soils with uniform and gradational texture profiles - largely Calcarosols 600 700 km2 • Alkaline strongly sodic to sodic texture contrast soils - largely Sodosols 454 400 km2 • Non-alkaline sodic and strongly sodic neutral texture contrast soils - largely Sodosols 134 700 km2 • Non-alkaline sodic acid texture contrast soils - Sodosols and Kurosols 140 700 km2 Many Australian sodic soils have not developed by the traditional solonetz process of leaching of a solonchak, but rather have developed by the accumulation of sodium on the cation exchange complex in preference to the other exchangeable cations without any recognisable intermediate saline phase occurring. This is especially the case for the sodic, non-alkaline texture contrast soils or Sodosols. The major sodic soil group in WRB is the Solonetz soils. These require the presence of a Natric horizon which has to contain illuviated clay and at least 15% ESP. However, there is provision for Sodic qualifiers with at least 6% ESP for many other reference Soil Groups

Dynamics of Physical and Physicochemical Properties of Urban Soils under the Effect of Ice-Melting Salts

NASA Astrophysics Data System (ADS)

Azovtseva, N. A.; Smagin, A. V.

2018-01-01

Physical (water content, density, and air and water regimes) and physicochemical (electrical conductivity, pH, and SAR) properties of urban soils were investigated on test plots of Moscow to evaluate their dynamics under anthropogenic impact. The wilting point and the dependence of the capillary-sorption and total water potentials of the soil water content were determined in laboratory experiments with natural and artificially saline soil samples to evaluate the effect of salt antifreeze substances on water availability for plants under conditions of active application of deicing reagents. Seasonal dynamics of these parameters were investigated. It was found that electrolytes display a steady tendency for the accumulation and redistribution in the root zone rather than for their deep leaching despite humid climatic conditions in Moscow megalopolis. In summer, regular droughts result in drying of the root zone to critical values and to the concentration of electrolytes up to the values that make the total water potential of soil unsuitable for water uptake by roots. The key factor of soil degradation under the impact of electrolytes is the soil dispersity: the finer the texture, the higher the soil salinization and solonetzicity and the stronger irreversible changes in the soil water retention capacity and physical properties.

Leveraging Subsidence in Permafrost with Remotely Sensed Active Layer Thickness (ReSALT) Products

NASA Astrophysics Data System (ADS)

Schaefer, K. M.; Chen, A.; Chen, J.; Chen, R. H.; Liu, L.; Michaelides, R. J.; Moghaddam, M.; Parsekian, A.; Tabatabaeenejad, A.; Thompson, J. A.; Zebker, H. A.; Meyer, F. J.

2017-12-01

The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence in permafrost regions. Seasonal subsidence results from the expansion of soil water into ice as the surface soil or active layer freezes and thaws each year. Subsidence trends result from large-scale thaw of permafrost and from the melting and subsequent drainage of excess ground ice in permafrost-affected soils. The attached figure shows the 2006-2010 average seasonal subsidence from ReSALT around Barrow, Alaska. The average active layer thickness (the maximum surface thaw depth during summer) is 30-40 cm, resulting in an average seasonal subsidence of 1-3 cm. Analysis of the seasonal subsidence and subsidence trends provides valuable insights into important permafrost processes, such as the freeze/thaw of the active layer, large-scale thawing due to climate change, the impact of fire, and infrastructure vulnerability. ReSALT supports the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential NASA-ISRO Synthetic Aperture Radar (NISAR) product. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. Here we present examples of ReSALT products in Alaska to highlight the untapped potential of the InSAR technique to understand permafrost dynamics, with a strong emphasis on the underlying processes that drive the subsidence.

Microbial community biomass and structure in saline and non-saline soils associated with salt, boran tolerant poplar clones grown for the phytoremediation of selenium

USDA-ARS?s Scientific Manuscript database

The effect of naturally-occurring salts, boron (B), and selenium (Se) on soil microbial community composition associated with plants during different growing seasons used in bioremediation strategies is not known. This information is needed for developing sustainable remediation practices as soil mi...

[Effects of salt stress on physiological characters and salt-tolerance of Ulmus pumila in different habitats].

PubMed

Liu, Bing-Xiang; Wang, Zhi-Gang; Liang, Hai-Yong; Yang, Min-Sheng

2012-06-01

Taking the Ulmus pumila seedlings from three different habitats (medium-, mild-, and non-saline soils) as test materials, an experiment was conducted to study their salt-tolerance thresholds and physiological characteristic under different levels (0, 2, 4, 6, 8, and 10 g X kg(-1)) of salt stress. With increasing level of the salt stress, the seedlings taken from medium- and mild- saline habitats had a lower increment of leaf membrane permeability, Na+ content, and Na+/K+ but a higher increment of leaf proline, soluble sugar, and K+ contents, and a lower decrement of leaf starch content, net photosynthetic rate, transpiration rate, intercellular CO2 concentration, and stomatic conductance, as compared with the seedlings taken from non-saline habitat. The salt-tolerance thresholds of the seedlings taken from different habitats were in the order of medium- saline habitat (7.76 g X kg(-1)) > mild- saline habitat (7.37 g X kg(-1)) > non-saline habitat (6.95 g X kg(-1)). It was suggested that the U. pumila seedlings in medium- and mild-saline habitats had a stronger adaptability to saline soil environment than the U. pumila seedlings in non-saline soil environment.

Synthesis of soil-hydraulic properties and infiltration timescales in wildfire-affected soils

USGS Publications Warehouse

Ebel, Brian A.; Moody, John A.

2017-01-01

We collected soil-hydraulic property data from the literature for wildfire-affected soils, ash, and unburned soils. These data were used to calculate metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity (S) and wetting front potential (Ψf) were significantly different (lower) in burned soils compared with unburned soils, whereas field-saturated hydraulic conductivity (Kfs) was not significantly different. The magnitude and duration of the influence of capillarity during infiltration was greatly reduced in burned soils, causing faster ponding times in response to rainfall. Ash had large values of S and Kfs but moderate values of Ψf, compared with unburned and burned soils, indicating ash has long ponding times in response to rainfall. The ratio of S2/Kfs was nearly constant (~100 mm) for unburned soils but more variable in burned soils, suggesting that unburned soils have a balance between gravity and capillarity contributions to infiltration that may depend on soil organic matter, whereas in burned soils the gravity contribution to infiltration is greater. Changes in S and Kfs in burned soils act synergistically to reduce infiltration and accelerate and amplify surface runoff generation. Synthesis of these findings identifies three key areas for future research. First, short timescales of capillary influences on infiltration indicate the need for better measurements of infiltration at times less than 1 min to accurately characterize S in burned soils. Second, using parameter values, such as Ψf, from unburned areas could produce substantial errors in hydrologic modeling when used without adjustment for wildfire effects, causing parameter compensation and resulting underestimation of Kfs. Third, more thorough measurement campaigns that capture soil-structural changes, organic matter impacts, quantitative water repellency trends, and soil-water content along with soil-hydraulic properties could drive the

Salt composition of groundwater and reclaimed solonetzes in the Baraba Lowland

NASA Astrophysics Data System (ADS)

Semendyaeva, N. V.; Elizarov, N. V.

2017-10-01

Solonetzes of experimental trials established in 1981 and 1986 in the Baraba Lowland were examined. It was found that gypsum-based ameliorants improve the soil and lead to a decrease in the content of soluble salts in the soil profile. Exchange processes between cations of the soil adsorption complex and calcium of gypsum were particularly intensive in the first years after gypsum application. This resulted in a sharp rise in the content of soluble salts that migrated down the soil profile to the groundwater. In the following years, the reclaimed solonetzes were desalinized under the conditions of relatively stable groundwater level. On the 30th year after single gypsum application, the groundwater level sharply rose (to 50 cm), and the soil was subjected to the secondary salinization; the contents of bicarbonates, carbonates, and sodium in the soils increased. Spring leaching caused some desalinization, but the content of soluble salts in the upper soil meter increased again in the fall. A close correlation between the salt compositions of the groundwater and the reclaimed solonetzes was revealed.

Potential Use of Halophytes to Remediate Saline Soils

PubMed Central

Hasanuzzaman, Mirza; Nahar, Kamrun; Alam, Md. Mahabub; Bhowmik, Prasanta C.; Hossain, Md. Amzad; Rahman, Motior M.; Prasad, Majeti Narasimha Vara; Ozturk, Munir; Fujita, Masayuki

2014-01-01

Salinity is one of the rising problems causing tremendous yield losses in many regions of the world especially in arid and semiarid regions. To maximize crop productivity, these areas should be brought under utilization where there are options for removing salinity or using the salt-tolerant crops. Use of salt-tolerant crops does not remove the salt and hence halophytes that have capacity to accumulate and exclude the salt can be an effective way. Methods for salt removal include agronomic practices or phytoremediation. The first is cost- and labor-intensive and needs some developmental strategies for implication; on the contrary, the phytoremediation by halophyte is more suitable as it can be executed very easily without those problems. Several halophyte species including grasses, shrubs, and trees can remove the salt from different kinds of salt-affected problematic soils through salt excluding, excreting, or accumulating by their morphological, anatomical, physiological adaptation in their organelle level and cellular level. Exploiting halophytes for reducing salinity can be good sources for meeting the basic needs of people in salt-affected areas as well. This review focuses on the special adaptive features of halophytic plants under saline condition and the possible ways to utilize these plants to remediate salinity. PMID:25110683

[Effects of thinning on Calligonum arborescens growth and soil water-salt distribution in Tarim Desert Highway shelterbelt, Xinjiang of Northwest China].

PubMed

Zhang, Jian-Guo; Li, Ying-Gang; Xu, Xin-Wen; Lei, Jia-Qiang; Li, Sheng-Yu

2012-09-01

In order to understand the effects of thinning on the growth of Calligonum arborescens and the soil water-salt distribution in Tarim Desert Highway shelterbelt, a thinning experiment was conducted on an aged and declined C. arborescens woodland in a demonstration section of the shelterbelt, with the growth of C. arborescens and the soil water-salt distribution monitored. Thinning had no effects on the phenophase of C. arborescens, but after thinning, the growth of the current year plant height, crown width, ground diameter, and new branch length of reserved trees was larger than that of the control, and the increment was in the order of planting space 2 mx 1 m > 1 m x 1 m > the control, with significant differences among the treatments. The assimilation branch surface area in treatments 2 mx 1 m and 1 m x 1 m were 5.97 m2 and 5.22 m2 per plant, respectively, being significantly larger than the control (3.1 m2 per plant). The soil moisture content in 0-160 cm layer was significantly higher in treatments 2 m x 1 m and 1 mx 1 m than in the control, and increased obviously with thinning intensity. The soil salt content was in the order of control > planting space 1 m x 1 m > 2 m x 1 m, and the differences among the treatments were significant. It was suggested that the best reserved plant density after thinning was planting space 2 m x 1 m.

Can soil drying affect the sorption of pesticides in soil?

NASA Astrophysics Data System (ADS)

Chaplain, Véronique; Saint, Philippe; Mamy, Laure; Barriuso, Enrique

2010-05-01

The sorption of pesticides in soils mainly controls their further dispersion into the environment. Sorption is usually related to the physico-chemical properties of molecules but it also depends on the hydrophobic features of soils. However, the hydrophobicity of soils changes with wetting and drying cycles and this can be enhanced with climate change. The objective of this study was to measure by using controlled artificial soils the influence of the hydrophobic characteristic of soils on the retention of a model pesticide. Artificial soils consisted in silica particles covered by synthetic cationic polymers. Polymers were characterized by the molar ratio of monomers bearing an alkyl chain of 12C. Two polymers were used, with 20 and 80 % ratios, and the same degree of polymerization. In addition, porous and non-porous particles were used to study the accessibility notion and to measure the influence of diffusion on pesticide sorption kinetics. Lindane was chosen as model molecule because its adsorption is supposed mainly due to hydrophobic interactions. Results on polymers adsorption on silica showed that it was governed by electrostatic interactions, without any dependency of the hydrophobic ratio. Polymers covered the entire surface of porous particles. Kinetic measurements showed that lindane sorption was slowed in porous particles due to the molecular diffusion inside the microporosity. The adsorption of lindane on covered silica particles corresponded to a partition mechanism described by linear isotherms. The slope was determined by the hydrophobic ratio of polymers: the sorption of lindane was highest in the most hydrophobic artificial soil. As a result, modification in soil hydrophobicity, that can happen with climate change, might affect the sorption and the fate of pesticides. However additional experiments are needed to confirm these first results. Such artificial soils should be used as reference materials to compare the reactivity of pesticides, to

Microbial cooperation in the rhizosphere improves liquorice growth under salt stress

PubMed Central

Egamberdieva, Dilfuza; Wirth, Stephan; Li, Li; Abd-Allah, Elsayed Fathi

2017-01-01

ABSTRACT Liquorice (Glycyrrhiza uralensis Fisch.) is one of the most widely used plants in food production, and it can also be used as an herbal medicine or for reclamation of salt-affected soils. Under salt stress, inhibition of plant growth, nutrient acquisition and symbiotic interactions between the medicinal legume liquorice and rhizobia have been observed. We recently evaluated the interactions between rhizobia and root-colonizing Pseudomonas in liquorice grown in potting soil and observed increased plant biomass, nodule numbers and nitrogen content after combined inoculation compared to plants inoculated with Mesorhizobium alone. Several beneficial effects of microbes on plants have been reported; studies examining the interactions between symbiotic bacteria and root-colonizing Pseudomonas strains under natural saline soil conditions are important, especially in areas where a hindrance of nutrients and niches in the rhizosphere are high. Here, we summarize our recent observations regarding the combined application of rhizobia and Pseudomonas on the growth and nutrient uptake of liquorice as well as the salt stress tolerance mechanisms of liquorice by a mutualistic interaction with microbes. Our observations indicate that microbes living in the rhizosphere of liquorice can form a mutualistic association and coordinate their involvement in plant adaptations to stress tolerance. These results support the development of combined inoculants for improving plant growth and the symbiotic performance of legumes under hostile conditions. PMID:27780398

Organic matter dynamics along a salinity gradient in Siberian steppe soils

NASA Astrophysics Data System (ADS)

Bischoff, Norbert; Mikutta, Robert; Shibistova, Olga; Dohrmann, Reiner; Herdtle, Daniel; Gerhard, Lukas; Fritzsche, Franziska; Puzanov, Alexander; Silanteva, Marina; Grebennikova, Anna; Guggenberger, Georg

2018-01-01

Salt-affected soils will become more frequent in the next decades as arid and semiarid ecosystems are predicted to expand as a result of climate change. Nevertheless, little is known about organic matter (OM) dynamics in these soils, though OM is crucial for soil fertility and represents an important carbon sink. We aimed at investigating OM dynamics along a salinity and sodicity gradient in the soils of the southwestern Siberian Kulunda steppe (Kastanozem, non-sodic Solonchak, Sodic Solonchak) by assessing the organic carbon (OC) stocks, the quantity and quality of particulate and mineral-associated OM in terms of non-cellulosic neutral sugar contents and carbon isotopes (δ13C, 14C activity), and the microbial community composition based on phospholipid fatty acid (PLFA) patterns. Aboveground biomass was measured as a proxy for plant growth and soil OC inputs. Our hypotheses were that (i) soil OC stocks decrease along the salinity gradient, (ii) the proportion and stability of particulate OM is larger in salt-affected Solonchaks compared to non-salt-affected Kastanozems, (iii) sodicity reduces the proportion and stability of mineral-associated OM, and (iv) the fungi : bacteria ratio is negatively correlated with salinity. Against our first hypothesis, OC stocks increased along the salinity gradient with the most pronounced differences between topsoils. In contrast to our second hypothesis, the proportion of particulate OM was unaffected by salinity, thereby accounting for only < 10 % in all three soil types, while mineral-associated OM contributed > 90 %. Isotopic data (δ13C, 14C activity) and neutral sugars in the OM fractions indicated a comparable degree of OM transformation along the salinity gradient and that particulate OM was not more persistent under saline conditions. Our third hypothesis was also rejected, as Sodic Solonchaks contained more than twice as much mineral-bound OC than the Kastanozems, which we ascribe to the flocculation of OM and mineral

The toxicity of different lead salts to Enchytraeus crypticus in relation to bioavailability in soil.

PubMed

Zhang, Lulu; Van Gestel, Cornelis A M

2017-08-01

The present study aimed to assess the bioavailability and toxicity of lead nitrate and lead chloride to Enchytraeus crypticus in a natural standard soil. Worms were exposed to Pb-spiked soil for 21 d, and survival and reproduction were related to total, 0.01 M CaCl 2 -extractable, and porewater Pb concentrations in the soil and internal concentrations in the surviving animals. The Pb availability for Pb(NO 3 ) 2 and PbCl 2 was similar, as confirmed by Langmuir and Freundlich isotherms. The Pb concentrations in surviving worms increased with increasing Pb concentrations in the soil and did not differ for the 2 Pb salts. Lead was toxic to E. crypticus at median lethal concentrations (LC50s) of 543 and 779 mg Pb/kg dry soil and median effect concentrations (EC50s) of 189 and 134 mg Pb/kg dry soil, for Pb(NO 3 ) 2 and PbCl 2 , respectively. Mortality of E. crypticus was related to internal Pb concentrations in the worms rather than to total or available Pb concentrations in the soil, whereas reproduction toxicity was better explained from Pb concentrations in 0.01 M CaCl 2 extracts or porewater of the test soil than from total Pb concentrations in the soil or Pb concentrations in the worms. Overall, the bioavailability and toxicity of Pb(NO 3 ) 2 and PbCl 2 to E. crypticus in LUFA 2.2 soil did not differ. Environ Toxicol Chem 2017;36:2083-2091. © 2017 SETAC. © 2017 SETAC.

Environmental aspects of produced-water salt releases in onshore and coastal petroleum-producing areas of the conterminous U.S. - a bibliography

USGS Publications Warehouse

Otton, James K.

2006-01-01

Environmental effects associated with the production of oil and gas have been reported since the first oil wells were drilled in the Appalachian Basin in Pennsylvania and Kentucky in the early to mid-1800s. The most significant of these effects are the degradation of soils, ground water, surface water, and ecosystems they support by releases of suspended and dissolved hydrocarbons and co-produced saline water. Produced water salts are less likely than hydrocarbons to be adsorbed by mineral phases in the soil and sediment and are not subject to degradation by biologic processes. Sodium is a major dissolved constituent in most produced waters and it causes substantial degradation of soils through altering of clays and soil textures and subsequent erosion. Produced water salts seem to have the most wide-ranging effects on soils, water quality, and ecosystems. Trace elements, including boron, lithium, bromine, fluorine, and radium, also occur in elevated concentrations in some produced waters. Many trace elements are phytotoxic and are adsorbed and may remain in soils after the saline water has been flushed away. Radium-bearing scale and sludge found in oilfield equipment and discarded on soils pose additional hazards to human health and ecosystems. This bibliography includes studies from across the oil- and natural-gas-producing areas of the conterminous United States that were published in the last 80 yrs. The studies describe the effects of produced water salts on soils, water quality, and ecosystems. Also included are reports that describe (1) the inorganic chemistry of produced waters included in studies of formation waters for various purposes, (2) other sources of salt affecting water quality that may be mistaken for produced water effects, (3) geochemical and geophysical techniques that allow discrimination of salt sources, (4) remediation technologies designed to repair damage caused to soils and ground water by produced water salts, and (5) contamination by

Na/Cl molar ratio changes during a salting cycle and its application to the estimation of sodium retention in salted watersheds.

PubMed

Sun, Hongbing; Huffine, Maria; Husch, Jonathan; Sinpatanasakul, Leeann

2012-08-01

Using soil column experiments and data from natural watersheds, this paper analyzes the changes in Na/Cl molar ratios during a salting cycle of aqueous-soil systems. The soil column experiments involved introducing NaCl salt at various initial concentrations into multiple soil columns. At the start of a salting cycle in the column experiments, sodium was adsorbed more than chloride due to cation exchange processes. As a result, the initial Na/Cl molar ratio in column effluent was lower than 1, but increased thereafter. One-dimensional PHREEQC geochemical transport simulations also were conducted to further quantify these trends under more diverse scenarios. The experimentally determined Na/Cl molar ratio pattern was compared to observations in the annual salting cycle of four natural watersheds where NaCl is the dominant applied road deicing salt. Typically, Na/Cl molar ratios were low from mid-winter to early spring and increased after the bulk of the salt was flushed out of the watersheds during the summer, fall and early winter. The established relationship between the Na/Cl molar ratios and the amount of sodium retention derived from the column experiments and computer simulations present an alternative approach to the traditional budget analysis method for estimating sodium retention when the experimental and natural watershed patterns of Na/Cl molar ratio change are similar. Findings from this study enhance the understanding of sodium retention and help improve the scientific basis for future environmental policies intended to suppress the increase of sodium concentrations in salted watersheds. Copyright © 2012 Elsevier B.V. All rights reserved.

Overexpression of a novel salt stress-induced glycine-rich protein gene from alfalfa causes salt and ABA sensitivity in Arabidopsis.

PubMed

Long, Ruicai; Yang, Qingchuan; Kang, Junmei; Zhang, Tiejun; Wang, Huimin; Li, Mingna; Zhang, Ze

2013-08-01

We cloned a novel salt stress-induced glycine-rich protein gene ( MsGRP ) from alfalfa. Its overexpression retards seed germination and seedling growth of transgenic Arabidopsis after salt and ABA treatments. Since soil salinity is one of the most significant abiotic stresses, salt tolerance is required to overcome salinity-induced reductions in crop productivity. Many glycine-rich proteins (GRPs) have been implicated in plant responses to environmental stresses, but the function and importance of some GRPs in stress responses remain largely unknown. Here, we report on a novel salt stress-induced GRP gene (MsGRP) that we isolated from alfalfa. Compared with some glycine-rich RNA-binding proteins, MsGRP contains no RNA recognition motifs and localizes in the cell membrane or cell wall according to the subcellular localization result. MsGRP mRNA is induced by salt, abscisic acid (ABA), and drought stresses in alfalfa seedlings, and its overexpression driven by a constitutive cauliflower mosaic virus-35S promoter in Arabidopsis plants confers salinity and ABA sensitivity compared with WT plants. MsGRP retards seed germination and seedling growth of transgenic Arabidopsis plants after salt and ABA treatments, which implies that MsGRP may affect germination and growth through an ABA-dependent regulation pathway. These results provide indirect evidence that MsGRP plays important roles in seed germination and seedling growth of alfalfa under some abiotic stress conditions.

Rethinking infiltration in wildfire-affected soils

USGS Publications Warehouse

Ebel, Brian A.; Moody, John A.

2013-01-01

Wildfires frequently result in natural hazards such as flash floods (Yates et al., 2001) and debris flows (Cannon et al., 2001a,b; Gabet and Sternberg, 2008). One of the principal causes of the increased risk of post-wildfire hydrologically driven hazards is reduced in filtration rates (e.g. Scott and van Wyk, 1990; Cerdà, 1998; Robichaud, 2000; Martin and Moody, 2001). Beyond the reduction in peak infiltration rate, there is mounting evidence that the fundamental physics of infiltration in wild fire-affected soils is different from unburned soils (e.g. Imeson et al., 1992; Moody et al., 2009; Moody and Ebel, 2012).Understanding post-wildfire hydrology is critical given the increasing wildfire incidence in the western USA (Westerling et al., 2006) and elsewhere in the world (Kasischke and Turetsky, 2006; Holz and Veblen, 2011; Pausas and Fernández-Muñoz, 2012). Wildfire is a disturbance event with global distribution (Bowman et al., 2009; Krawchuk et al., 2009; Pechony and Shindell, 2010; Moritz et al., 2012), and with increasing populations moving into fire-prone areas, understanding post-wildfire infiltration is of increasing importance for predicting post-wildfire consequences. Runoff is generally controlled by the infiltration-excess mechanism in fire-affected soils (e.g. Mayor et al., 2007; Onda et al., 2008; Kinner and Moody, 2010). It is essential that the fire community have conceptual models, physical equations and tools (i.e. numerical models) to predict infiltration and thus excess rainfall (after Horton, 1933), which can provide estimates of peak discharge, start of runoff, time to peak and total runoff for hydroclimatic scenarios after wildfires. Reductions in saturated hydraulic conductivity Ksat [LT-1] are common for fire-affected soils, and the relatively low values observed explain the elevated flash flood hazards (e.g. Ksat of 1–100 mm h-1 , Robichaud, 2000; Yates et al., 2000; Martin and Moody, 2001; Robichaud et al

Environment degeneration affects habitat diversity of Tamarix spp. in arid zone

NASA Astrophysics Data System (ADS)

Li, Tiejun; Yang, Weikang

2003-07-01

There are 18 species of Tamarix spp. in China and 16 of them in Xinjiang. As a group of bushes which widespread in salty and sandy land in arid zone, Tamarix spp. had gotten more and more attention by ecologists because of their unique bio-ecological characteristics, ecological and social economy functions. Wide Distribution of Tamarix spp. affects ecological environment stabilization of arid zone in western China. The modern distribution and habitat of Tamarix spp. diversity in Xinjiang were studied in this paper. Result revealed that water (surface water and high groundwater ) is the critical environment factor which determines the modern distribution of Tamarix spp.. Depend on analyzing groundwater lever and salt content of soil(two environment factors), author divided the habitat of Tamarix spp. into six type groups (low salt type with high groundwater, middle salt type with high groundwater, high salt type with high groundwater, low salt type with low groundwater and middle salt type with low groundwater etc.) which consisting of ten habitat types. Habitat of Tamarix spp. in Xinjiang never exists in isolation, but associate with each other. The groundwater lever and salt content of soil varies with the lapse of time, then habitats transform from one type into another and species of Tamarix spp. in habitats transforms accordingly.

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

Spatial heterogeneity of plant-soil feedback affects root interactions and interspecific competition.

PubMed

Hendriks, Marloes; Ravenek, Janneke M; Smit-Tiekstra, Annemiek E; van der Paauw, Jan Willem; de Caluwe, Hannie; van der Putten, Wim H; de Kroon, Hans; Mommer, Liesje

2015-08-01

Plant-soil feedback is receiving increasing interest as a factor influencing plant competition and species coexistence in grasslands. However, we do not know how spatial distribution of plant-soil feedback affects plant below-ground interactions. We investigated the way in which spatial heterogeneity of soil biota affects competitive interactions in grassland plant species. We performed a pairwise competition experiment combined with heterogeneous distribution of soil biota using four grassland plant species and their soil biota. Patches were applied as quadrants of 'own' and 'foreign' soils from all plant species in all pairwise combinations. To evaluate interspecific root responses, species-specific root biomass was quantified using real-time PCR. All plant species suffered negative soil feedback, but strength was species-specific, reflected by a decrease in root growth in own compared with foreign soil. Reduction in root growth in own patches by the superior plant competitor provided opportunities for inferior competitors to increase root biomass in these patches. These patterns did not cascade into above-ground effects during our experiment. We show that root distributions can be determined by spatial heterogeneity of soil biota, affecting plant below-ground competitive interactions. Thus, spatial heterogeneity of soil biota may contribute to plant species coexistence in species-rich grasslands. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Mobilization of PCBs and lindane from soil during in vitro digestion and their distribution among bile salt micelles and proteins of human digestive fluid and the soil

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

Oomen, A.G.; Sips, A.J.A.M.; Groten, J.P.

2000-01-15

Children can take up contaminated soil via hand-to-mouth behavior. The contaminants can be mobilized from the soil by digestive juices and thus become available for intestinal absorption. In the present study components of an in vitro digestion model were varied to study their effect on the mobilization of several PCBs and lindane from surrogate soil (OECD-medium). Approximately 35% of the PCBs and 57% of lindane were bioaccessible after a default digestion. Since the mobilization was independent of the spiking level, a partitioning-based model could describe the distribution of the test compounds. Fitting the data to the model yielded a ratiomore » of partitioning coefficients that indicated that approximately 60% of the PCBs were sorbed to the OECD-medium, 25% to bile salt micelles, and 15% to proteins. The respective values for lindane were 40%, 23%, and 32%. The relatively large fraction of the mobilized compounds that was sorbed to bile salt micelles indicates that micelles play a central role in making hydrophobic compounds bioaccessible. The distribution model is suitable for explaining the results reported in several literature studies and can be used to extrapolate the physiological parameters for the worst case situation and trends in the bioaccessible fraction.« less

A Trail of Salts

NASA Technical Reports Server (NTRS)

2004-01-01

This graph shows the relative abundances of sulfur (in the form of sulfur tri-oxide) and chlorine at three Meridiani Planum sites: soil measured in the small crater where Opportunity landed; the rock dubbed 'McKittrick' in the outcrop lining the inner edge of the crater; and the rock nicknamed 'Guadalupe,' also in the outcrop. The 'McKittrick' data shown here were taken both before and after the rover finished grinding the rock with its rock abrasion tool to expose fresh rock underneath. The 'Guadalupe' data were taken after the rover grounded the rock. After grinding both rocks, the sulfur abundance rose to high levels, nearly five times higher than that of the soil. This very high sulfur concentration reflects the heavy presence of sulfate salts (approximately 30 percent by weight) in the rocks. Chloride and bromide salts are also indicated. Such high levels of salts strongly suggest the rocks contain evaporite deposits, which form when water evaporates or ice sublimes into the atmosphere.

Simulating Salt Movement and Transformation using a Coupled Reactive Transport Model in Variably-Saturated Groundwater Systems

NASA Astrophysics Data System (ADS)

Tavakoli Kivi, S.; Bailey, R. T.; Gates, T.

2016-12-01

Salinization is one of the major concerns in irrigated agricultural landscapes. Increasing salinity concentrations are due principally to evaporative concentration; dissolution of salts from weathered minerals and bedrock; and a high water table that results from excessive irrigation, canal seepage, and a lack of efficient drainage systems; leading to decreasing crop yield. High groundwater salinity loading to nearby river systems also impacts downstream areas, with saline river water diverted for application on irrigated fields. In this study, a solute transport model coupled with equilibrium chemistry reactions has been developed to simulate transport of individual salt ions in regional-scale aquifer systems and thereby investigate strategies for salinity remediation. The physically-based numerical model is based on the UZF-RT3D variably-saturated, multi-species groundwater reactive transport modeling code, and accounts for advection, dispersion, carbon and nitrogen cycling, oxidation-reduction reactions, and salt ion equilibrium chemistry reactions such as complexation, ion exchange, and precipitation/dissolution. Each major salt ion (sulfate, chloride, bicarbonate, calcium, sodium, magnesium, potassium) is included. The model has been tested against measured soil salinity at a small scale (soil profile) and against soil salinity, groundwater salinity, and groundwater salinity loading to surface water at the regional scale (500 km2) in the Lower Arkansas River Valley (LARV) in southeastern Colorado, an area acutely affected by salinization for many decades and greatly influenced by gypsum deposits. Preliminary results of using the model in scenario analysis suggest that increasing irrigation efficiency, sealing earthen canals, and rotational fallowing of land can decrease the groundwater salt load to the Arkansas River by 50 to 70% and substantially lower soil salinity in the root zone.

Low-concentration kinetics of atmospheric CH{sub 4} oxidation in soil and mechanism of NH{sub 4}{sup +} inhibition

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

Gulledge, J.; Schimel, J.P.

1998-11-01

NH{sub 4}{sup +} inhibition kinetics for CH{sub 4} oxidation were examined at near-atmospheric CH{sub 4} concentrations in three upland forest soils. Whether NH{sub 4}{sup +}-independent salt effects could be neutralized by adding nonammoniacal salts to control samples in lieu of deionized water was also investigated. Because the levels of exchangeable endogenous NH{sub 4}{sup +} were very low in the three soils, desorption of endogenous NH{sub 4}{sup +} was not a significant factor in this study. The K{sub m(app)} values for water-treated controls were 9.8, 22, and 57 nM for temperate pine, temperate hardwood, and birch taiga soils, respectively. At CH{submore » 4} concentrations of {le}15 {micro}l liter{sup {minus}1}, oxidation followed first-order kinetics in the fine-textured taiga soil, whereas the coarse-textured temperate soils exhibited Michaelis-Menten kinetics. Compared to water controls, the K{sub m(app)} values in the temperate soils increased in the presence of NH{sub 4}{sup +} salts, whereas the V{sub max(app)} values decreased substantially, indicating that there was a mixture of competitive and noncompetitive inhibition mechanisms for whole NH{sub 4}{sup +} salts. Compared to the corresponding K{sup +} salt controls, the K{sub m(app)} values for NH{sub 4}{sup +} salts increased substantially, whereas the V{sub max(app)} values remained virtually unchanged, indicating that NH{sub 4}{sup +} acted by competitive inhibition. Nonammoniacal salts caused inhibition to increase with increasing CH{sub 4} concentrations in all three soils. In the birch taiga soil, this trend occurred with both NH{sub 4}{sup +} and K{sup +} salts, and the slope of the increase was not affected by the addition of NH{sub 4}{sup +}. Hence, the increase in inhibition resulted from an NH{sub 4}{sup +}-independent mechanism.« less

Ranking factors affecting emissions of GHG from incubated agricultural soils.

PubMed

García-Marco, S; Ravella, S R; Chadwick, D; Vallejo, A; Gregory, A S; Cárdenas, L M

2014-07-01

Agriculture significantly contributes to global greenhouse gas (GHG) emissions and there is a need to develop effective mitigation strategies. The efficacy of methods to reduce GHG fluxes from agricultural soils can be affected by a range of interacting management and environmental factors. Uniquely, we used the Taguchi experimental design methodology to rank the relative importance of six factors known to affect the emission of GHG from soil: nitrate (NO 3 - ) addition, carbon quality (labile and non-labile C), soil temperature, water-filled pore space (WFPS) and extent of soil compaction. Grassland soil was incubated in jars where selected factors, considered at two or three amounts within the experimental range, were combined in an orthogonal array to determine the importance and interactions between factors with a L 16 design, comprising 16 experimental units. Within this L 16 design, 216 combinations of the full factorial experimental design were represented. Headspace nitrous oxide (N 2 O), methane (CH 4 ) and carbon dioxide (CO 2 ) concentrations were measured and used to calculate fluxes. Results found for the relative influence of factors (WFPS and NO 3 - addition were the main factors affecting N 2 O fluxes, whilst glucose, NO 3 - and soil temperature were the main factors affecting CO 2 and CH 4 fluxes) were consistent with those already well documented. Interactions between factors were also studied and results showed that factors with little individual influence became more influential in combination. The proposed methodology offers new possibilities for GHG researchers to study interactions between influential factors and address the optimized sets of conditions to reduce GHG emissions in agro-ecosystems, while reducing the number of experimental units required compared with conventional experimental procedures that adjust one variable at a time.

Ranking factors affecting emissions of GHG from incubated agricultural soils

PubMed Central

García-Marco, S; Ravella, S R; Chadwick, D; Vallejo, A; Gregory, A S; Cárdenas, L M

2014-01-01

Agriculture significantly contributes to global greenhouse gas (GHG) emissions and there is a need to develop effective mitigation strategies. The efficacy of methods to reduce GHG fluxes from agricultural soils can be affected by a range of interacting management and environmental factors. Uniquely, we used the Taguchi experimental design methodology to rank the relative importance of six factors known to affect the emission of GHG from soil: nitrate (NO3−) addition, carbon quality (labile and non-labile C), soil temperature, water-filled pore space (WFPS) and extent of soil compaction. Grassland soil was incubated in jars where selected factors, considered at two or three amounts within the experimental range, were combined in an orthogonal array to determine the importance and interactions between factors with a L16 design, comprising 16 experimental units. Within this L16 design, 216 combinations of the full factorial experimental design were represented. Headspace nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations were measured and used to calculate fluxes. Results found for the relative influence of factors (WFPS and NO3− addition were the main factors affecting N2O fluxes, whilst glucose, NO3− and soil temperature were the main factors affecting CO2 and CH4 fluxes) were consistent with those already well documented. Interactions between factors were also studied and results showed that factors with little individual influence became more influential in combination. The proposed methodology offers new possibilities for GHG researchers to study interactions between influential factors and address the optimized sets of conditions to reduce GHG emissions in agro-ecosystems, while reducing the number of experimental units required compared with conventional experimental procedures that adjust one variable at a time. PMID:25177207

Tracing salt provenance in McMurdo Dry Valley soils by using magnesium isotopes

NASA Astrophysics Data System (ADS)

Cuozzo, N.; Sletten, R. S.; Hu, Y.; Teng, F. Z.

2016-12-01

The McMurdo Dry Valleys (MDV) are a hyper-arid polar desert that contain a rich geologic record in permafrost that has been preserved over millions of years. Soluble salts accumulate through the surface and subsurface of MDV soils. Sources of salt accumulation include mineral weathering, transport of marine aerosols, and possible glacial meltwater. This project seeks to study the provenance of these salts in a 30-meter ice cemented permafrost core collected in Beacon Valley. The ice-rich core was thawed and water extracted by centrifugation using a double bottom centrifuge tube. The extracted water was analyzed for ionic composition, pH, and Mg isotopes (δ26Mg), which are useful in interpreting provenance. The ionic and δ26Mg values show a disconformity at around 7 meters. Above 7 meters, δ26Mg values vary between -0.76 to -0.52, indicating rock-water interactions. These samples are isotopically heavier than the lower section of the core and can be explained by a slow accumulation of sediment and warmer near-surface temperatures that allow for greater chemical weathering of dolerite in the ice-cemented, debris-rich permafrost core. This interpretation is also supported by the more alkaline pH values (7.07 - 7.54) above 7 meters, which is consistent with chemical weathering of dolerite. In comparison, salt samples below 7 meters have δ26Mg values between -0.95 to -0.84, which overlaps with modern seawater (δ26Mg = -0.83 ± 0.09) and is fairly consistent throughout the rest of the core. Furthermore, below a depth of 7 meters, Mg/Na and Mg/K ratios are also similar to modern seawater. In summary, these results indicate differing sources of salts along the depth of the Dry Valley permafrost core, changing from a marine-dominant signature in the deeper section to a stronger weathered signal in the upper section. Additional work dating the sediment using cosmogenic nuclides provides a history for the burial of the sediments in the permafrost core and may provide

High-salt diets during pregnancy affected fetal and offspring renal renin-angiotensin system.

PubMed

Mao, Caiping; Liu, Rong; Bo, Le; Chen, Ningjing; Li, Shigang; Xia, Shuixiu; Chen, Jie; Li, Dawei; Zhang, Lubo; Xu, Zhice

2013-07-01

Intrauterine environments are related to fetal renal development and postnatal health. Influence of salty diets during pregnancy on renal functions and renin-angiotensin system (RAS) was determined in the ovine fetuses and offspring. Pregnant ewes were fed high-salt diet (HSD) or normal-salt diet (NSD) for 2 months during middle-to-late gestation. Fetal renal functions, plasma hormones, and mRNA and protein expressions of the key elements of renal RAS were measured in the fetuses and offspring. Fetal renal excretion of sodium was increased while urine volume decreased in the HSD group. Fetal blood urea nitrogen was increased, while kidney weight:body weight ratio decreased in the HSD group. The altered ratio was also observed in the offspring aged 15 and 90 days. Maternal and fetal plasma antidiuretic hormone was elevated without changes in plasma renin activity and Ang I levels, while plasma Ang II was decreased. The key elements of local renal RAS, including angiotensinogen, angiotensin converting enzyme (ACE), ACE2, AT1, and AT2 receptor expression in both mRNA and protein, except renin, were altered following maternal high salt intake. The results suggest that high intake of salt during pregnancy affected fetal renal development associated with an altered expression of the renal key elements of RAS, some alterations of fetal origins remained after birth as possible risks in developing renal or cardiovascular diseases.

Biochar and lignite affect H+-ATPase and H+-PPase activities in root tonoplast and nutrient contents of mung bean under salt stress.

PubMed

Torabian, Shahram; Farhangi-Abriz, Salar; Rathjen, Judith

2018-05-31

This research was conducted to evaluate effects of biochar (50 and 100 g kg -1 soil) and lignite (50 and 100 g kg -1 soil) treatments on H + -ATPase and H + -PPase activity of root tonoplast, nutrient content, and performance of mung bean under salt stress. High saline conditions increased H + -ATPase and H + -PPase activities in root tonoplast, sodium (Na) content, reactive oxygen species (H 2 O 2 and O 2 - ) generation, relative electrolyte leakage (REL) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) activity in root and leaf, but decreased relative water content (RWC), chlorophyll content index, leaf area, potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn) and iron (Fe) content of plant tissues, root and shoot dry weight of mung bean. Lignite and biochar treatments decreased the H + -ATPase and H + -PPase activities of root tonoplast under salt stress. Moreover, these treatments increased the cation exchange capacity of soil and nutrient values in plant tissues. Biochar and lignite diminished the generation of reactive oxygen species and DPPH activity in root and leaf cells, and these superior effects improved chlorophyll content index, leaf area and growth of mung bean under both conditions. In general, the results of this study demonstrated that biochar and lignite decreased the entry of Na ion into the cells, enriched plant cells with nutrients, and consequently improved mung bean performance under salt toxicity. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Factors Affecting Soil Microbial Community Structure in Tomato Cropping Systems

USDA-ARS?s Scientific Manuscript database

Soil and rhizosphere microbial communities in agroecosystems may be affected by soil, climate, plant species, and management. We identified some of the most important factors controlling microbial biomass and community structure in an agroecosystem utilizing tomato plants with the following nine tre...

Salt tolerant SUV3 overexpressing transgenic rice plants conserve physicochemical properties and microbial communities of rhizosphere.

PubMed

Sahoo, Ranjan K; Ansari, Mohammad W; Tuteja, Renu; Tuteja, Narendra

2015-01-01

Key concerns in the ecological evaluation of GM crops are undesirably spread, gene flow, other environmental impacts, and consequences on soil microorganism's biodiversity. Numerous reports have highlighted the effects of transgenic plants on the physiology of non-targeted rhizospheric microbes and the food chain via causing adverse effects. Therefore, there is an urgent need to develop transgenics with insignificant toxic on environmental health. In the present study, SUV3 overexpressing salt tolerant transgenic rice evaluated in New Delhi and Cuttack soil conditions for their effects on physicochemical and biological properties of rhizosphere. Its cultivation does not affect soil properties viz., pH, Eh, organic C, P, K, N, Ca, Mg, S, Na and Fe(2+). Additionally, SUV3 rice plants do not cause any change in the phenotype, species characteristics and antibiotic sensitivity of rhizospheric bacteria. The population and/or number of soil organisms such as bacteria, fungi and nematodes were unchanged in the soil. Also, the activity of bacterial enzymes viz., dehydrogenase, invertase, phenol oxidases, acid phosphatases, ureases and proteases was not significantly affected. Further, plant growth promotion (PGP) functions of bacteria such as siderophore, HCN, salicylic acid, IAA, GA, zeatin, ABA, NH3, phosphorus metabolism, ACC deaminase and iron tolerance were, considerably, not influenced. The present findings suggest ecologically pertinent of salt tolerant SUV3 rice to sustain the health and usual functions of the rhizospheric organisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Spatial and temporal variability of soil hydraulic properties of topsoil affected by soil erosion

NASA Astrophysics Data System (ADS)

Nikodem, Antonin; Kodesova, Radka; Jaksik, Ondrej; Jirku, Veronika; Klement, Ales; Fer, Miroslav

2014-05-01

This study is focused on the comparison of soil hydraulic properties of topsoil that is affected by erosion processes. In order to include variable morphological and soil properties along the slope three sites - Brumovice, Vidim and Sedlčany were selected. Two transects (A, B) and five sampling sites along each one were chosen. Soil samples were taken in Brumovice after the tillage and sowing of winter wheat in October 2010 and after the wheat harvest in August 2011. At locality Vidim and Sedlčany samples were collected in May and August 2012. Soil hydraulic properties were studied in the laboratory on the undisturbed 100-cm3 soil samples placed in Tempe cells using the multi-step outflow test. Soil water retention data points were obtained by calculating water balance in the soil sample at each pressure head step of the experiment. The single-porosity model in HYDRUS-1D was applied to analyze the multi-step outflow and to obtain the parameters of soil hydraulic properties using the numerical inversion. The saturated hydraulic conductivities (Ks) and unsaturated hydraulic conductivities (Kw) for the pressure head of -2 cm of topsoil were also measured after the harvest using Guelph permeameter and Minidisk tensiometer, respectively. In general soil water retention curves measured before and after vegetation period apparently differed, which indicated soil material consolidation and soil-porous system rearrangement. Soil water retention curves obtained on the soil samples and hydraulic conductivities measured in the field reflected the position at the elevation transect and the effect of erosion/accumulation processes on soil structure and consequently on the soil hydraulic properties. The highest Ks values in Brumovice were obtained at the steepest parts of the elevation transects, that have been the most eroded. The Ks values at the bottom parts decreased due to the sedimentation of eroded soil particles. The change of the Kw values along transects didn't show

Differences in soil solution chemistry between soils amended with nanosized CuO or Cu reference materials: implications for nanotoxicity tests.

PubMed

McShane, Heather V A; Sunahara, Geoffrey I; Whalen, Joann K; Hendershot, William H

2014-07-15

Soil toxicity tests for metal oxide nanoparticles often include micrometer-sized oxide and metal salt treatments to distinguish between toxicity from nanometer-sized particles, non-nanometer-sized particles, and dissolved ions. Test result will be confounded if each chemical form has different effects on soil solution chemistry. We report on changes in soil solution chemistry over 56 days-the duration of some standard soil toxicity tests-in three soils amended with 500 mg/kg Cu as nanometer-sized CuO (nano), micrometer-sized CuO (micrometer), or Cu(NO3)2 (salt). In the CuO-amended soils, the log Cu2+ activity was initially low (minimum -9.48) and increased with time (maximum -5.20), whereas in the salt-amended soils it was initially high (maximum -4.80) and decreased with time (minimum -6.10). The Cu2+ activity in the nano-amended soils was higher than in the micrometer-amended soils for at least the first 11 days, and lower than in the salt-amended soils for at least 28 d. The pH, and dissolved Ca and Mg concentrations in the CuO-amended soils were similar, but the salt-amended soils had lower pH for at least 14 d, and higher Ca and Mg concentrations throughout the test. Soil pretreatments such as leaching and aging prior to toxicity tests are suggested.

Nitrogen starvation affects bacterial adhesion to soil

PubMed Central

Borges, Maria Tereza; Nascimento, Antônio Galvão; Rocha, Ulisses Nunes; Tótola, Marcos Rogério

2008-01-01

One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation. PMID:24031246

Assessing the role of endophytic bacteria in the halophyte Arthrocnemum macrostachyum salt tolerance.

PubMed

Navarro-Torre, S; Barcia-Piedras, J M; Mateos-Naranjo, E; Redondo-Gómez, S; Camacho, M; Caviedes, M A; Pajuelo, E; Rodríguez-Llorente, I D

2017-03-01

There is an increasing interest to use halophytes for revegetation of salt affected ecosystems, as well as in understanding their mechanisms of salt tolerance. We hypothesized that bacteria from the phyllosphere of these plants might play a key role in its high tolerance to excessive salinity. Eight endophytic bacteria belonging to Bacillus and closely related genera were isolated from phyllosphere of the halophyte Arthrocnemum macrostachyum growing in salty agricultural soils. The presence of plant-growth promoting (PGP) properties, enzymatic activities and tolerance towards NaCl was determined. Effects of inoculation on seeds germination and adult plant growth under experimental NaCl treatments (0, 510 and 1030 mM NaCl) were studied. Inoculation with a consortium including the best performing bacteria improved considerably the kinetics of germination and the final germination percentage of A. macrostachyum seeds. At high NaCl concentrations (1030 mM), inoculation of plants mitigated the effects of high salinity on plant growth and physiological performance and, in addition, this consortium appears to have increased the potential of A. macrostachyum to accumulate Na + in its shoots, thus improving sodium phytoextraction capacity. Bacteria isolated from A. macrostachyum phyllosphere seem to play an important role in plant salt tolerance under stressing salt concentrations. The combined use of A. macrostachyum and its microbiome can be an adequate tool to enhance plant adaptation and sodium phytoextraction during restoration of salt degraded soils. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Effects of catalase on chloroplast arrangement in Opuntia streptacantha chlorenchyma cells under salt stress.

PubMed

Arias-Moreno, Diana Marcela; Jiménez-Bremont, Juan Francisco; Maruri-López, Israel; Delgado-Sánchez, Pablo

2017-08-17

In arid and semiarid regions, low precipitation rates lead to soil salinity problems, which may limit plant establishment, growth, and survival. Herein, we investigated the NaCl stress effect on chlorophyll fluorescence, photosynthetic-pigments, movement and chloroplasts ultrastructure in chlorenchyma cells of Opuntia streptacantha cladodes. Cladodes segments were exposed to salt stress at 0, 100, 200, and 300 mM NaCl for 8, 16, and 24 h. The results showed that salt stress reduced chlorophyll content, F v /F m , ΦPSII, and qP values. Under the highest salt stress treatments, the chloroplasts were densely clumped toward the cell center and thylakoid membranes were notably affected. We analyzed the effect of exogenous catalase in salt-stressed cladode segments during 8, 16, and 24 h. The catalase application to salt-stressed cladodes counteracted the NaCl adverse effects, increasing the chlorophyll fluorescence parameters, photosynthetic-pigments, and avoided chloroplast clustering. Our results indicate that salt stress triggered the chloroplast clumping and affected the photosynthesis in O. streptacantha chlorenchyma cells. The exogenous catalase reverted the H 2 O 2 accumulation and clustering of chloroplast, which led to an improvement of the photosynthetic efficiency. These data suggest that H 2 O 2 detoxification by catalase is important to protect the chloroplast, thus conserving the photosynthetic activity in O. streptacantha under stress.

Infiltration and runoff generation processes in fire-affected soils

USGS Publications Warehouse

Moody, John A.; Ebel, Brian A.

2014-01-01

Post-wildfire runoff was investigated by combining field measurements and modelling of infiltration into fire-affected soils to predict time-to-start of runoff and peak runoff rate at the plot scale (1 m2). Time series of soil-water content, rainfall and runoff were measured on a hillslope burned by the 2010 Fourmile Canyon Fire west of Boulder, Colorado during cyclonic and convective rainstorms in the spring and summer of 2011. Some of the field measurements and measured soil physical properties were used to calibrate a one-dimensional post-wildfire numerical model, which was then used as a ‘virtual instrument’ to provide estimates of the saturated hydraulic conductivity and high-resolution (1 mm) estimates of the soil-water profile and water fluxes within the unsaturated zone.Field and model estimates of the wetting-front depth indicated that post-wildfire infiltration was on average confined to shallow depths less than 30 mm. Model estimates of the effective saturated hydraulic conductivity, Ks, near the soil surface ranged from 0.1 to 5.2 mm h−1. Because of the relatively small values of Ks, the time-to-start of runoff (measured from the start of rainfall),  tp, was found to depend only on the initial soil-water saturation deficit (predicted by the model) and a measured characteristic of the rainfall profile (referred to as the average rainfall acceleration, equal to the initial rate of change in rainfall intensity). An analytical model was developed from the combined results and explained 92–97% of the variance of  tp, and the numerical infiltration model explained 74–91% of the variance of the peak runoff rates. These results are from one burned site, but they strongly suggest that  tp in fire-affected soils (which often have low values of Ks) is probably controlled more by the storm profile and the initial soil-water saturation deficit than by soil hydraulic properties.

Effects of Soil Salinity on Sucrose Metabolism in Cotton Fiber

PubMed Central

Liu, Jingran; Luo, Junyu; Zhao, Xinhua; Dong, Helin; Ma, Yan; Sui, Ning; Zhou, Zhiguo; Meng, Yali

2016-01-01

Cotton (Gosspium hirsutum L.) is classified as a salt tolerant crop. However, its yield and fiber quality are negatively affected by soil salinity. Studies on the enzymatic differences in sucrose metabolism under different soil salinity levels are lacking. Therefore, field experiments, using two cotton cultivars, CCRI-79 (salt-tolerant) and Simian 3 (salt-sensitive), were conducted in 2013 and 2014 at three different salinity levels (1.15 dS m-1 [low soil salinity], 6.00 dS m-1 [medium soil salinity], and 11.46 dS m-1 [high soil salinity]). The objective was to elucidate the effects of soil salinity on sucrose content and the activity of key enzymes that are related to sucrose metabolism in cotton fiber. Results showed that as the soil salinity increased, cellulose content, sucrose content, and sucrose transformation rate declined; the decreases in cellulose content and sucrose transformation rate caused by the increase in soil salinity were more in Simian 3 than those in CCRI-79. With increase in soil salinity, activities of sucrose metabolism enzymes sucrose phophate synthase (SPS), acidic invertase, and alkaline invertase were decreased, whereas sucrose synthase (SuSy) activity increased. However, the changes displayed in the SuSy and SPS activities in response to increase in soil salinity were different and the differences were large between the two cotton cultivars. These results illustrated that suppressed cellulose synthesis and sucrose metabolism under high soil salinity were mainly due to the change in SPS, SuSy, and invertase activities, and the difference in cellulose synthesis and sucrose metabolism in fiber for the two cotton cultivars in response to soil salinity was determined mainly by both SuSy and SPS activities. PMID:27227773

Engineering salt-tolerant Brassica plants: characterization of yield and seed oil quality in transgenic plants with increased vacuolar sodium accumulation.

PubMed

Zhang, H X; Hodson, J N; Williams, J P; Blumwald, E

2001-10-23

Transgenic Brassica napus plants overexpressing AtNHX1, a vacuolar Na(+)/H(+) antiport from Arabidopsis thaliana, were able to grow, flower, and produce seeds in the presence of 200 mM sodium chloride. Although the transgenic plants grown in high salinity accumulated sodium up to 6% of their dry weight, growth of the these plants was only marginally affected by the high salt concentration. Moreover, seed yields and the seed oil quality were not affected by the high salinity of the soil. Our results demonstrate the potential use of these transgenic plants for agricultural use in saline soils. Our findings, showing that the modification of a single trait significantly improved the salinity tolerance of this crop plant, suggest that with a combination of breeding and transgenic plants it could be possible to produce salt-tolerant crops with far fewer target traits than had been anticipated.

Microbially Mediated Plant Salt Tolerance and Microbiome-based Solutions for Saline Agriculture.

PubMed

Qin, Yuan; Druzhinina, Irina S; Pan, Xueyu; Yuan, Zhilin

2016-11-15

Soil salinization adversely affects plant growth and has become one of the major limiting factors for crop productivity worldwide. The conventional approach, breeding salt-tolerant plant cultivars, has often failed to efficiently alleviate the situation. In contrast, the use of a diverse array of microorganisms harbored by plants has attracted increasing attention because of the remarkable beneficial effects of microorganisms on plants. Multiple advanced '-omics' technologies have enabled us to gain insights into the structure and function of plant-associated microbes. In this review, we first focus on microbe-mediated plant salt tolerance, in particular on the physiological and molecular mechanisms underlying root-microbe symbiosis. Unfortunately, when introducing such microbes as single strains to soils, they are often ineffective in improving plant growth and stress tolerance, largely due to competition with native soil microbial communities and limited colonization efficiency. Rapid progress in rhizosphere microbiome research has revived the belief that plants may benefit more from association with interacting, diverse microbial communities (microbiome) than from individual members in a community. Understanding how a microbiome assembles in the continuous compartments (endosphere, rhizoplane, and rhizosphere) will assist in predicting a subset of core or minimal microbiome and thus facilitate synthetic re-construction of microbial communities and their functional complementarity and synergistic effects. These developments will open a new avenue for capitalizing on the cultivable microbiome to strengthen plant salt tolerance and thus to refine agricultural practices and production under saline conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

Salt-tolerant and -sensitive alfalfa (Medicago sativa) cultivars have large variations in defense responses to the lepidopteran insect Spodoptera litura under normal and salt stress condition

PubMed Central

Lei, Yunting; Liu, Qing; Hettenhausen, Christian; Cao, Guoyan; Tan, Qing; Zhao, Weiye; Lin, Honghui

2017-01-01

In nature, plants are often exposed to multiple stress factors at the same time. Yet, little is known about how plants modulate their physiology to counteract simultaneous abiotic and biotic stresses, such as soil salinity and insect herbivory. In this study, insect performance bioassays, phytohormone measurements, quantification of transcripts, and protein determination were employed to study the phenotypic variations of two alfalfa (Medicago sativa) cultivars in response to insect Spodoptera litura feeding under normal and salt stress condition. When being cultivated in normal soil, the salt-tolerant alfalfa cultivar Zhongmu-1 exhibited lower insect resistance than did the salt-sensitive cultivar Xinjiang Daye. Under salinity stress, the defense responses of Xinjiang Daye were repressed, whereas Zhongmu-1 did not show changes in resistance levels. It is likely that salinity influenced the resistance of Xinjiang Daye through suppressing the accumulation of jasmonic acid-isoleucine (JA-Ile), which is the bioactive hormone inducing herbivore defense responses, leading to attenuated trypsin proteinase inhibitor (TPI) activity. Furthermore, exogenous ABA supplementation suppressed the insect herbivory-induced JA/JA-Ile accumulation and levels of JAR1 (jasmonate resistant 1) and TPI, and further decreased the resistance of Xinjiang Daye, whereas Zhongmu-1 showed very little response to the increased ABA level. We propose a mechanism, in which high levels of abscisic acid induced by salt treatment may affect the expression levels of JAR1 and consequently decrease JA-Ile accumulation and thus partly suppress the defense of Xinjiang Daye against insects under salt stress. This study provides new insight into the mechanism by which alfalfa responds to concurrent abiotic and biotic stresses. PMID:28719628

Salt-tolerant and -sensitive alfalfa (Medicago sativa) cultivars have large variations in defense responses to the lepidopteran insect Spodoptera litura under normal and salt stress condition.

PubMed

Lei, Yunting; Liu, Qing; Hettenhausen, Christian; Cao, Guoyan; Tan, Qing; Zhao, Weiye; Lin, Honghui; Wu, Jianqiang

2017-01-01

In nature, plants are often exposed to multiple stress factors at the same time. Yet, little is known about how plants modulate their physiology to counteract simultaneous abiotic and biotic stresses, such as soil salinity and insect herbivory. In this study, insect performance bioassays, phytohormone measurements, quantification of transcripts, and protein determination were employed to study the phenotypic variations of two alfalfa (Medicago sativa) cultivars in response to insect Spodoptera litura feeding under normal and salt stress condition. When being cultivated in normal soil, the salt-tolerant alfalfa cultivar Zhongmu-1 exhibited lower insect resistance than did the salt-sensitive cultivar Xinjiang Daye. Under salinity stress, the defense responses of Xinjiang Daye were repressed, whereas Zhongmu-1 did not show changes in resistance levels. It is likely that salinity influenced the resistance of Xinjiang Daye through suppressing the accumulation of jasmonic acid-isoleucine (JA-Ile), which is the bioactive hormone inducing herbivore defense responses, leading to attenuated trypsin proteinase inhibitor (TPI) activity. Furthermore, exogenous ABA supplementation suppressed the insect herbivory-induced JA/JA-Ile accumulation and levels of JAR1 (jasmonate resistant 1) and TPI, and further decreased the resistance of Xinjiang Daye, whereas Zhongmu-1 showed very little response to the increased ABA level. We propose a mechanism, in which high levels of abscisic acid induced by salt treatment may affect the expression levels of JAR1 and consequently decrease JA-Ile accumulation and thus partly suppress the defense of Xinjiang Daye against insects under salt stress. This study provides new insight into the mechanism by which alfalfa responds to concurrent abiotic and biotic stresses.

Modeling salinization and recovery of road salt-impacted lakes in temperate regions based on long-term monitoring of Lake George, New York (USA) and its drainage basin.

PubMed

Sutherland, J W; Norton, S A; Short, J W; Navitsky, C

2018-05-08

Road salt mitigates winter highway icing but accumulates in watershed soils and receiving waters, affecting soil chemistry and physical, biological, and ecological processes. Despite efforts to reduce salt loading in watersheds, accumulated cations and Cl - continue to impact tributaries and lakes, and the recovery process is not well understood. Lake George, New York (USA) is typical of many temperate lakes at risk for elevated Cl - concentrations from winter deicing; the lake salt concentration increased by ~3.4% year -1 since 1980. Here, we evaluated the ionic composition in Finkle Brook, a major watershed draining to Lake George, studied intermittently since 1970 and typical of other salt-impacted Lake George tributaries. Salt loading in the Lake George basin since the 1940s displaced cations from exchange sites in basin soils; these desorbed cations follow a simple ion-exchange model, with lower sodium and higher calcium, magnesium and potassium fluxes in runoff. Reduced salt application in the Finkle Brook watershed during the low-snow winter of 2015-2016 led to a 30-40% decline of Cl - and base cations in the tributary, implying a Cl - soil half-life of 1-2 years. We developed a conceptual model that describes cation behavior in runoff from a watershed that received road salt loading over a long period of time, and then recovery following reduced salt loading. Next, we developed a dynamic model estimating time to steady-state for Cl - in Lake George with road salt loading starting in 1940, calibrating the model with tributary runoff and lake chemistry data from 1970 and 1980, respectively, and forecasting Cl - concentrations in Lake George based on various scenarios of salt loading and soil retention of Cl - . Our Lake George models are readily adaptable to other temperate lakes with drainage basins where road salt is applied during freezing conditions and paved roads cover a portion of the watershed. Copyright © 2018 Elsevier B.V. All rights reserved.

Short-term effects of tidal flooding on soil nitrogen mineralization in a Chinese tidal salt marsh

NASA Astrophysics Data System (ADS)

Gao, Haifeng; Bai, Junhong; Deng, Xiaoya; Lu, Qiongqiong; Ye, Xiaofei

2018-02-01

Tidal flooding is an important control of nitrogen biogeochemistry in wetland ecosystems of Yellow River Delta, China. Variations in hydrology could change soil redox dynamics and conditions for microorganisms living. A tidal simulation experiment was designed to extract tidal flooding effect on nitrogen mineralization of salt marsh soil. Inorganic nitrogen and relevant enzyme were measured during the 20-day incubation period. Considering the variation of both inorganic N and enzymes, nitrogen mineralization process in tidal salt marsh could be divided into 2 phases of short term response and longtime adaption by around 12th incubation day as the inflection point. Soil ammonium nitrogen (NH4+-N) and volatilized ammonia (NH3) occupied the mineralization process since nitrate nitrogen (NO3--N) was not detected over whole incubation period. NH4+-N varied fluctuant and increased significantly after 12 day's incubation. Released NH3 reached to peak value of 14.24 mg m-2 d-1 at the inflection point and declined thereafter. Inorganic nitrogen released according to net nitrogen mineralization rate (RM) under the tidal flooding condition without plant uptake except first 2 days. However, during the transitional period of 6-12 days, RM decreased notably to almost 0 and increased again after inflection point with the value of 0.182 mg kg-1 d-1. It might be due to the change of microbial composition and function when soil shifted from oxic to anoxic, which were reflected by arylamidase, urease and fluorescein diacetate. Fluorescein diacetate hydrolysis and arylamidase had the similar variation of U style with decreasing activities before 12 days' incubation. All the enzymes measured in this experiment increased after inflection point. Whereas, urease activity kept constant from 2 to 12 days. Alternant oxidation reduction condition would increase N loss through denitrification and ammonia volatilization during the transitional period, while more inorganic nitrogen would be

Development of predictive mapping techniques for soil survey and salinity mapping

NASA Astrophysics Data System (ADS)

Elnaggar, Abdelhamid A.

Conventional soil maps represent a valuable source of information about soil characteristics, however they are subjective, very expensive, and time-consuming to prepare. Also, they do not include explicit information about the conceptual mental model used in developing them nor information about their accuracy, in addition to the error associated with them. Decision tree analysis (DTA) was successfully used in retrieving the expert knowledge embedded in old soil survey data. This knowledge was efficiently used in developing predictive soil maps for the study areas in Benton and Malheur Counties, Oregon and accessing their consistency. A retrieved soil-landscape model from a reference area in Harney County was extrapolated to develop a preliminary soil map for the neighboring unmapped part of Malheur County. The developed map had a low prediction accuracy and only a few soil map units (SMUs) were predicted with significant accuracy, mostly those shallow SMUs that have either a lithic contact with the bedrock or developed on a duripan. On the other hand, the developed soil map based on field data was predicted with very high accuracy (overall was about 97%). Salt-affected areas of the Malheur County study area are indicated by their high spectral reflectance and they are easily discriminated from the remote sensing data. However, remote sensing data fails to distinguish between the different classes of soil salinity. Using the DTA method, five classes of soil salinity were successfully predicted with an overall accuracy of about 99%. Moreover, the calculated area of salt-affected soil was overestimated when mapped using remote sensing data compared to that predicted by using DTA. Hence, DTA could be a very helpful approach in developing soil survey and soil salinity maps in more objective, effective, less-expensive and quicker ways based on field data.

Stochastic modeling of soil salinity

NASA Astrophysics Data System (ADS)

Suweis, S.; Porporato, A. M.; Daly, E.; van der Zee, S.; Maritan, A.; Rinaldo, A.

2010-12-01

A minimalist stochastic model of primary soil salinity is proposed, in which the rate of soil salinization is determined by the balance between dry and wet salt deposition and the intermittent leaching events caused by rainfall events. The equations for the probability density functions of salt mass and concentration are found by reducing the coupled soil moisture and salt mass balance equations to a single stochastic differential equation (generalized Langevin equation) driven by multiplicative Poisson noise. Generalized Langevin equations with multiplicative white Poisson noise pose the usual Ito (I) or Stratonovich (S) prescription dilemma. Different interpretations lead to different results and then choosing between the I and S prescriptions is crucial to describe correctly the dynamics of the model systems. We show how this choice can be determined by physical information about the timescales involved in the process. We also show that when the multiplicative noise is at most linear in the random variable one prescription can be made equivalent to the other by a suitable transformation in the jump probability distribution. We then apply these results to the generalized Langevin equation that drives the salt mass dynamics. The stationary analytical solutions for the probability density functions of salt mass and concentration provide insight on the interplay of the main soil, plant and climate parameters responsible for long term soil salinization. In particular, they show the existence of two distinct regimes, one where the mean salt mass remains nearly constant (or decreases) with increasing rainfall frequency, and another where mean salt content increases markedly with increasing rainfall frequency. As a result, relatively small reductions of rainfall in drier climates may entail dramatic shifts in longterm soil salinization trends, with significant consequences, e.g. for climate change impacts on rain fed agriculture.

Soil Organic Carbon Pools and Stocks in Permafrost-Affected Soils on the Tibetan Plateau

PubMed Central

Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

2013-01-01

The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm−3) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm−3) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg−1. Higher SOC contents (320 g kg−1) were found in OPOM while MOM had the lowest SOC contents (29 g kg−1). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0–30 cm depth) account for 10.4 kg m−2, compared to 3.4 kg m−2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation. PMID:23468904

Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

PubMed

Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

2013-01-01

The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm(-3)) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm(-3)) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1). Higher SOC contents (320 g kg(-1)) were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1)). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth) account for 10.4 kg m(-2), compared to 3.4 kg m(-2) in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

Does vegetation prevent wave erosion of salt marsh edges?

PubMed

Feagin, R A; Lozada-Bernard, S M; Ravens, T M; Möller, I; Yeager, K M; Baird, A H

2009-06-23

This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.

The functional consequences of mis-sense mutations affecting an intra-molecular salt bridge in arylsulphatase A.

PubMed Central

Schestag, Frank; Yaghootfam, Afshin; Habetha, Matthias; Poeppel, Peter; Dietz, Frank; Klein, Roger A; Zlotogora, Joel; Gieselmann, Volkmar

2002-01-01

Metachromatic leukodystrophy is a lysosomal storage disorder caused by the deficiency of arylsulphatase A. We describe the functional consequences of three mis-sense mutations in the arylsulphatase A gene (Asp-335-Val, Arg-370-Trp and Arg-370-Gln), affecting an apparent intramolecular Asp-335 to Arg-370 salt bridge, and interpret the effects and clinical consequences on the basis of the three-dimensional structure of arylsulphatase A. Asp-335-Val and Arg-370-Trp substitutions each cause a complete loss of enzyme activity and are associated with the most severe form of the human disease, whereas the Arg-370-Gln-substituted enzyme retains some residual activity, being found in a patient suffering from the milder juvenile form of the disease. Detailed analysis reveals that formation of the apparent salt bridge depends critically on the presence of aspartic acid and arginine residues at positions 335 and 370, respectively. Substitution by various other amino acids, including glutamic acid and lysine, affects enzyme function severely. Biosynthesis and immunoprecipitation studies indicate that the Asp-335-Val substitution affects folding of arylsulphatase A more severely than either the Arg-370-Trp or Arg-370-Gln substitutions. In vitro mutagenesis data show that clinical severity correlates with the space occupied by residue 370. The combination with structural data suggests that the bulky tryptophan residue broadens the cleft held together by the apparent salt bridge, whereas the smaller glutamine residue still allows the cleft to close, yielding a less severely affected enzyme. The position of residue 370 in the three-dimensional structure of the enzyme provides a plausible explanation for the differing severities in loss of enzyme function caused by the mutations and thus the clinical phenotype. PMID:12086582

Temporal variability in Cu speciation, phytotoxicity, and soil microbial activity of Cu-polluted soils as affected by elevated temperature.

PubMed

Fu, Qing-Long; Weng, Nanyan; Fujii, Manabu; Zhou, Dong-Mei

2018-03-01

Global warming has obtained increasing attentions due to its multiple impacts on agro-ecosystem. However, limited efforts had been devoted to reveal the temporal variability of metal speciation and phytotoxicity of heavy metal-polluted soils affected by elevated temperature under the global warming scenario. In this study, effects of elevated temperature (15 °C, 25 °C, and 35 °C) on the physicochemical properties, microbial metabolic activities, and phytotoxicity of three Cu-polluted soils were investigated by a laboratory incubation study. Soil physicochemical properties were observed to be significantly altered by elevated temperature with the degree of temperature effect varying in soil types and incubation time. The Biolog and enzymatic tests demonstrated that soil microbial activities were mainly controlled and decreased with increasing incubation temperature. Moreover, plant assays confirmed that the phytotoxicity and Cu uptake by wheat roots were highly dependent on soil types but less affected by incubation temperature. Overall, the findings in this study have highlighted the importance of soil types to better understand the temperature-dependent alternation of soil properties, Cu speciation and bioavailability, as well as phytotoxicity of Cu-polluted soils under global warming scenario. The present study also suggests the necessary of investigating effects of soil types on the transport and accumulation of toxic elements in soil-crop systems under global warming scenario. Copyright © 2017 Elsevier Ltd. All rights reserved.

Derivation of ecological criteria for copper in land-applied biosolids and biosolid-amended agricultural soils.

PubMed

Lu, Tao; Li, Jumei; Wang, Xiaoqing; Ma, Yibing; Smolders, Erik; Zhu, Nanwen

2016-12-01

The difference in availability between soil metals added via biosolids and soluble salts was not taken into account in deriving the current land-applied biosolids standards. In the present study, a biosolids availability factor (BAF) approach was adopted to investigate the ecological thresholds for copper (Cu) in land-applied biosolids and biosolid-amended agricultural soils. First, the soil property-specific values of HC5 add (the added hazardous concentration for 5% of species) for Cu 2+ salt amended were collected with due attention to data for organisms and soils relevant to China. Second, a BAF representing the difference in availability between soil Cu added via biosolids and soluble salts was estimated based on long-term biosolid-amended soils, including soils from China. Third, biosolids Cu HC5 input values (the input hazardous concentration for 5% of species of Cu from biosolids to soil) as a function of soil properties were derived using the BAF approach. The average potential availability of Cu in agricultural soils amended with biosolids accounted for 53% of that for the same soils spiked with same amount of soluble Cu salts and with a similar aging time. The cation exchange capacity was the main factor affecting the biosolids Cu HC5 input values, while soil pH and organic carbon only explained 24.2 and 1.5% of the variation, respectively. The biosolids Cu HC5 input values can be accurately predicted by regression models developed based on 2-3 soil properties with coefficients of determination (R 2 ) of 0.889 and 0.945. Compared with model predicted biosolids Cu HC5 input values, current standards (GB4284-84) are most likely to be less protective in acidic and neutral soil, but conservative in alkaline non-calcareous soil. Recommendations on ecological criteria for Cu in land-applied biosolids and biosolid-amended agriculture soils may be helpful to fill the gaps existing between science and regulations, and can be useful for Cu risk assessments in

Leaf conductance and carbon gain under salt-stressed conditions

NASA Astrophysics Data System (ADS)

Volpe, V.; Manzoni, S.; Marani, M.; Katul, G.

2011-12-01

Exposure of plants to salt stress is often accompanied by reductions in leaf photosynthesis and in stomatal and mesophyll conductances. To separate the effects of salt stress on these quantities, a model based on the hypothesis that carbon gain is maximized subject to a water loss cost is proposed. The optimization problem of adjusting stomatal aperture for maximizing carbon gain at a given water loss is solved for both a non-linear and a linear biochemical demand function. A key novel theoretical outcome of the optimality hypothesis is an explicit relationship between the stomatal and mesophyll conductances that can be evaluated against published measurements. The approaches here successfully describe gas-exchange measurements reported for olive trees (Olea europea L.) and spinach (Spinacia oleraceaL.) in fresh water and in salt-stressed conditions. Salt stress affected both stomatal and mesophyll conductances and photosynthetic efficiency of both species. The fresh water/salt water comparisons show that the photosynthetic capacity is directly reduced by 30%-40%, indicating that reductions in photosynthetic rates under increased salt stress are not due only to a limitation of CO2diffusion. An increase in salt stress causes an increase in the cost of water parameter (or marginal water use efficiency) exceeding 100%, analogous in magnitude to findings from extreme drought stress studies. The proposed leaf-level approach can be incorporated into physically based models of the soil-plant-atmosphere system to assess how saline conditions and elevated atmospheric CO2 jointly impact transpiration and photosynthesis.

Soil properties affecting wheat yields following drilling-fluid application.

PubMed

Bauder, T A; Barbarick, K A; Ippolito, J A; Shanahan, J F; Ayers, P D

2005-01-01

Oil and gas drilling operations use drilling fluids (mud) to lubricate the drill bit and stem, transport formation cuttings to the surface, and seal off porous geologic formations. Following completion of the well, waste drilling fluid is often applied to cropland. We studied potential changes in soil compaction as indicated by cone penetration resistance, pH, electrical conductivity (EC(e)), sodium adsorption ratio (SAR), extractable soil and total straw and grain trace metal and nutrient concentrations, and winter wheat (Triticum aestivum L. 'TAM 107') grain yield following water-based, bentonitic drilling-fluid application (0-94 Mg ha(-1)) to field test plots. Three methods of application (normal, splash-plate, and spreader-bar) were used to study compaction effects. We measured increasing SAR, EC(e), and pH with drilling-fluid rates, but not to levels detrimental to crop production. Field measurements revealed significantly higher compaction within areas affected by truck travel, but also not enough to affect crop yield. In three of four site years, neither drilling-fluid rate nor application method affected grain yield. Extractions representing plant availability and plant analyses results indicated that drilling fluid did not significantly increase most trace elements or nutrient concentrations. These results support land application of water-based bentonitic drilling fluids as an acceptable practice on well-drained soils using controlled rates.

Helping crops stand up to salt

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

Raeburn, P.

1985-05-01

A new approach to the problem of increasing soil salinity is to raise salt-tolerant plants. The search for such plants involves finding new applications for naturally occurring salt-resistant plants (halophytes), using conventional breeding techniques to identify and strengthen crop varieties known to have better-than-average salt tolerance, and applying recombinant DNA methods to introduce salt resistance into existing plants. One promising plant is salicornia, which produces oil high in polyunsaturates at a greater yield than soybeans. Two varieties of atriplex yield as much animal feed as alfalfa and can be harvested several times a year. Seed companies are supporting the research.

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.

Aggregate Stability and Erodibility of Purple Soil on Sloping Farmland as affected by different Soil Thickness

NASA Astrophysics Data System (ADS)

Huang, Xinjun; Zhang, Qingwen; Chen, Shanghong; Dong, Yuequn; Xiao, Meijia; Hamed, Lamy Mamdoh Mohamed

2017-04-01

Soil thickness is basic limiting condition for purple soil, not only due to its effect on crop production, but also its effect on soil structure. Steady-state of soil thickness will be achieved over time, as result the soil aggregate which the key factor of soil erodibility can be enhanced as well. However, the effect of soil thickness on aggregates stability and the characteristics of soil erodibility in sloping land have not yet fully understood.A field survey was conducted in hilly area of Sichuan region located in southeast China to study the relationship between soil aggregate stability and soil erodibility on sloping farmland under different four thickness (100cm, 80cm, 60cm, 30cm) of purple soil. Based on two different sieving methods (Dry and Wet sieving), we analyzed soil aggregate stability and its effect on soil erodibility within depth of 0-30cm soil layers. The results indicated that: Water stable aggregate on sloping farmland was ranged between 37.9% to 58.6%, where it increased with increasing the soil thickness. Moreover, fractal dimension calculated from dry-sieving and wet-sieving was 2.06-2.49 and 2.70-2.85 respectively, where it decreased with decreasing the soil thickness. The overall soil erodibility was 0.05-1.00 and a negative significant correlation was found between soil aggregate stability and erodibility(P<0.01). Moreover, farmland with thick soil profile tended to be high in soil erodibility within the top soil layer (0-30cm). The results reveal that soil thickness can affect soil aggregate stability as well as erodibility. As soil thickness increased, the top soil became more stable and less erodible. Keywords：purple soil; soil thickness; soil aggregate；soil erodibility

Research on screening of suitable forage grasses in coastal saline - alkaline soil

NASA Astrophysics Data System (ADS)

Yue, Xiaoyu; Han, Xin; Song, Qianhong; Yang, Xu; Zhou, Qingyun

2017-11-01

The screening of salt-tolerant plants can provide suitable tree species for the afforestation of coastal salinity and maintain biodiversity and ecological stability. The research was based on the study of seven grasses, such as high fescue, the bermuda grass, the thyme, the rye grass, the precocious grass, the third leaf, and the red three leaves. Each pasture was planted in three different kinds of soil, such as salt alkali soil, salt alkali soil + ecological bag and non-saline alkali soil. The effect of salt alkali soil on germinating time, germination rate and grass growth was analyzed. The effects of ecological bag on soil salt and the growth and germination of grass was also analyzed in order to provide the reference basis for the widespread and systematic selection of salt-tolerant plants, with the grass being selected for the suitable ecological bag.

Does Short-term Litter Input Manipulation Affect Soil Respiration and the Carbon-isotopic Signature of Soil Respired CO2

NASA Astrophysics Data System (ADS)

Cheng, X.; Wu, J.

2016-12-01

Global change greatly alters the quality and quantity of plant litter inputs to soils, and further impacts soil organic matter (SOM) dynamics and soil respiration. However, the process-based understanding of how soil respiration may change with future shift in litter input is not fully understood. The Detritus Input and Removal Treatment (DIRT) experiment was conducted in coniferous forest (Platycladus orientalis (Linn.) Franco) ecosystem of central China to investigate the impact of above- and belowground litter input on soil respiration and the carbon-isotopic signature of soil respired CO2. Short-term (1-2 years) litter input manipulation significantly affected soil respiration, based on annual flux values, soil respiration was 31.9%, 20.5% and 37.2% lower in no litter (NL), no root (NR) and no input (NRNL), respectively, compared to control (CK). Whereas double litter (DL) treatment increased soil respiration by 9.1% compared to CK. The recalcitrance index of carbon (RIC) and the relative abundance of fungi increased under litter removal or root exclusion treatment (NL, NR and NRNL) compared to CK. Basal soil respiration was positively related to liable C and microbial biomass and negatively related to RIC and fungi to bacteria (F: B) ratio. The carbon-isotopic signature of soil respired CO2 enriched under litter removal and no input treatment, and slightly depleted under litter addition treatment compared to CK. Our results suggest that short-term litter input manipulation can affect the soil respiration by altering substrate availability and microbial community structure, and also impact the carbon-isotopic signature of soil respired CO2 possibly duo to change in the component of soil respiration and soil microclimate.

Does vegetation prevent wave erosion of salt marsh edges?

PubMed Central

Feagin, R. A.; Lozada-Bernard, S. M.; Ravens, T. M.; Möller, I.; Yeager, K. M.; Baird, A. H.

2009-01-01

This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves. PMID:19509340

Prolonged Soil Frost Affects Hydraulics and Phenology of Apple Trees

PubMed Central

Beikircher, Barbara; Mittmann, Claudia; Mayr, Stefan

2016-01-01

Restoration of an adequate water supply in spring is a prerequisite for survival of angiosperm trees in temperate regions. Trees must re-establish access to soil water and recover xylem functionality. We thus hypothesized that prolonged soil frost impairs recovery and affects hydraulics and phenology of Malus domestica var. ‘Golden Delicious.’ To test this hypothesis, over two consecutive winters the soil around some trees was insulated to prolong soil frosting, From mid-winter to early summer, the level of native embolism, the water and starch contents of wood, bark and buds were quantified at regular intervals and findings correlated with various phenological parameters, xylogenesis and fine root growth. The findings confirm that prolonged soil frost affects tree hydraulics and phenology but the severity of the effect depends on the climatic conditions. In both study years, percentage loss of hydraulic conductivity (PLC) decreased from about 70% at the end of winter to about 10% in May. Thereby, xylem refilling strongly coincided with a decrease of starch in wood and bark. Also treated trees were able to restore their hydraulic system by May but, in the warm spring of 2012, xylem refilling, the increases in water content and starch depolymerization were delayed. In contrast, in the cold spring of 2013 only small differences between control and treated trees were observed. Prolongation of soil frost also led to a delay in phenology, xylogenesis, and fine root growth. We conclude that reduced water uptake from frozen or cold soils impairs refilling and thus negatively impacts tree hydraulics and growth of apple trees in spring. Under unfavorable circumstances, this may cause severe winter damage or even dieback. PMID:27379146

Prolonged Soil Frost Affects Hydraulics and Phenology of Apple Trees.

PubMed

Beikircher, Barbara; Mittmann, Claudia; Mayr, Stefan

2016-01-01

Restoration of an adequate water supply in spring is a prerequisite for survival of angiosperm trees in temperate regions. Trees must re-establish access to soil water and recover xylem functionality. We thus hypothesized that prolonged soil frost impairs recovery and affects hydraulics and phenology of Malus domestica var. 'Golden Delicious.' To test this hypothesis, over two consecutive winters the soil around some trees was insulated to prolong soil frosting, From mid-winter to early summer, the level of native embolism, the water and starch contents of wood, bark and buds were quantified at regular intervals and findings correlated with various phenological parameters, xylogenesis and fine root growth. The findings confirm that prolonged soil frost affects tree hydraulics and phenology but the severity of the effect depends on the climatic conditions. In both study years, percentage loss of hydraulic conductivity (PLC) decreased from about 70% at the end of winter to about 10% in May. Thereby, xylem refilling strongly coincided with a decrease of starch in wood and bark. Also treated trees were able to restore their hydraulic system by May but, in the warm spring of 2012, xylem refilling, the increases in water content and starch depolymerization were delayed. In contrast, in the cold spring of 2013 only small differences between control and treated trees were observed. Prolongation of soil frost also led to a delay in phenology, xylogenesis, and fine root growth. We conclude that reduced water uptake from frozen or cold soils impairs refilling and thus negatively impacts tree hydraulics and growth of apple trees in spring. Under unfavorable circumstances, this may cause severe winter damage or even dieback.

Harvest residue and competing vegetation affect soil moisture, soil temperature, N availability, and Douglas-fir seedling growth.

Treesearch

Scott D. Roberts; Constance A. Harrington; Thomas A. Terry

2005-01-01

Decisions made during stand regeneration that affect subsequent levels of competing vegetation and residual biomass can have important short-term consequences for early stand growth, and may affect long-term site productivity. Competing vegetation clearly affects the availability of site resources such as soil moisture and nutrients. Harvest residues can also impact...

[Spatial differentiation and impact factors of Yutian Oasis's soil surface salt based on GWR model].

PubMed

Yuan, Yu Yun; Wahap, Halik; Guan, Jing Yun; Lu, Long Hui; Zhang, Qin Qin

2016-10-01

In this paper, topsoil salinity data gathered from 24 sampling sites in the Yutian Oasis were used, nine different kinds of environmental variables closely related to soil salinity were selec-ted as influencing factors, then, the spatial distribution characteristics of topsoil salinity and spatial heterogeneity of influencing factors were analyzed by combining the spatial autocorrelation with traditional regression analysis and geographically weighted regression model. Results showed that the topsoil salinity in Yutian Oasis was not of random distribution but had strong spatial dependence, and the spatial autocorrelation index for topsoil salinity was 0.479. Groundwater salinity, groundwater depth, elevation and temperature were the main factors influencing topsoil salt accumulation in arid land oases and they were spatially heterogeneous. The nine selected environmental variables except soil pH had significant influences on topsoil salinity with spatial disparity. GWR model was superior to the OLS model on interpretation and estimation of spatial non-stationary data, also had a remarkable advantage in visualization of modeling parameters.

Fluensulfone sorption and mobility as affected by soil type.

PubMed

Morris, Kelly A; Li, Xiao; Langston, David B; Davis, Richard F; Timper, Patricia; Grey, Timothy L

2018-02-01

Fluensulfone is a fluoroalkenyl chemical with activity against multiple genera of plant-parasitic nematodes. The adsorption, desorption, and mobility of fluensulfone were evaluated on multiple soils from the USA in laboratory and column experiments. Adsorption data regressed to the logarithmic Freundlich equation resulted in isotherm values of 1.24 to 3.28. Soil adsorption of fluensulfone correlated positively with organic matter (0.67) and clay (0.34), but negatively with sand (-0.54). Fluensulfone soil desorption correlated to pH (0.38) and cation exchange capacity (0.44). Fluensulfone desorption from Arredondo sand soil was 26%, and from other soils ranged from 43 to 70%. In mobility experiments, fluensulfone in the leachate peaked at 3 h, gradually declining and becoming undetectable after 9 h. Recovery from leachate was 45% of the initial fluensulfone applied to the soil surface. In separate experiments, 30-cm-long soil columns were saturated with 1 L of water, and then segregated into three 10-cm sections. Fluensulfone recovery was 41, 34, 29, and 13% in Chualar sandy loam, Arredondo sand, Greenville sandy clay loam, and Tifton loamy sand, respectively, in the top 10-cm section. Data indicated that soil organic matter and clay contents will affect sorption, mobility, and dissipation of fluensulfone. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Dynamics And Remediation Of Fine Textured Soils And Ground Water Contaminated With Salts And Chlorinated Organic Compounds

NASA Astrophysics Data System (ADS)

Murata, Alison; Naeth, M. Anne

2017-04-01

Soil and ground water are frequently contaminated by industrial activities, posing a potential risk to human and environmental health and limiting land use. Proper site management and remediation treatments can return contaminated areas to safe and useful states. Most remediation research focuses on single contaminants in coarse and medium textured soils. Contaminant mixtures are common and make remediation efforts complex due to differing chemical properties. Remediation in fine textured soils is difficult since their low hydraulic conductivities hinder addition of amendments into and removal of contaminated media out of the impacted zone. The objective of this research is to assess contaminant dynamics and potential remediation techniques for fine textured soil and ground water impacted by multiple contaminants in Edmonton, Alberta, Canada. The University of Alberta's Ellerslie Waste Management Facility was used to process liquid laboratory waste from 1972 to 2007. A waste water pond leak prior to 1984 resulted in salt and chlorinated organic compound contamination. An extensive annual ground water monitoring data set for the site is available since 1988. Analytical parameters include pH, electrical conductivity, major ions, volatile organic compounds, and metals. Data have been compared to Alberta Tier 1 Soil and Groundwater Remediation Guidelines to identify exceedances. The parameters of greatest concern, based on magnitude and frequency of detection, are electrical conductivity, sodium, chloride, chloroform, and dichloromethane. Spatial analyses of the data show that the contamination is focused in and down gradient of the former waste water pond. Temporal analyses show different trends depending on monitoring well location. Laboratory column experiments were used to assess leaching as a potential treatment for salt contamination in fine textured soils. Saturated hydraulic conductivity was measured for seven soils from two depth intervals with or without

Salinization of the soil solution decreases the further accumulation of salt in the root zone of the halophyte Atriplex nummularia Lindl. growing above shallow saline groundwater.

PubMed

Alharby, Hesham F; Colmer, Timothy D; Barrett-Lennard, Edward G

2018-01-01

Water use by plants in landscapes with shallow saline groundwater may lead to the accumulation of salt in the root zone. We examined the accumulation of Na + and Cl - around the roots of the halophyte Atriplex nummularia Lindl. and the impacts of this increasing salinity for stomatal conductance, water use and growth. Plants were grown in columns filled with a sand-clay mixture and connected at the bottom to reservoirs containing 20, 200 or 400 mM NaCl. At 21 d, Na + and Cl - concentrations in the soil solution were affected by the salinity of the groundwater, height above the water table and the root fresh mass density at various soil depths (P < 0.001). However, by day 35, the groundwater salinity and height above the water table remained significant factors, but the root fresh mass density was no longer significant. Regression of data from the 200 and 400 mM NaCl treatments showed that the rate of Na + accumulation in the soil increased until the Na + concentration reached ~250 mM within the root zone; subsequent decreases in accumulation were associated with decreases in stomatal conductance. Salinization of the soil solution therefore had a feedback effect on further salinization within the root zone. © 2017 John Wiley & Sons Ltd.

Theoretical considerations of soil retention. [dirtying of solar energy devices

NASA Technical Reports Server (NTRS)

Cuddihy, E. F.

1980-01-01

The performance of solar energy devices is adversely affected by surface soiling, and generally, the loss of performance increases with increases in the quantity of soil retained on their surfaces. To minimize performance losses caused by soiling, solar devices should not only be deployed in low soiling geographical areas, but employ surfaces or surfacing materials having low affinity for soil retention, maximum susceptibility to be naturally cleaned by wind, rain and snow, and to be readily cleanable by simple and inexpensive maintenance cleaning techniques. This article describes known and postulated mechanisms of soil retention on surfaces, and infers from these mechanisms that low soiling and easily cleanable surfaces should have low surface energy, and be hard, smooth, hydrophobic and chemically clean of sticky materials and water soluble salts.

Genomic, transcriptomic, and proteomic approaches towards understanding the molecular mechanisms of salt tolerance in Frankia strains isolated from Casuarina trees.

PubMed

Oshone, Rediet; Ngom, Mariama; Chu, Feixia; Mansour, Samira; Sy, Mame Ourèye; Champion, Antony; Tisa, Louis S

2017-08-18

Soil salinization is a worldwide problem that is intensifying because of the effects of climate change. An effective method for the reclamation of salt-affected soils involves initiating plant succession using fast growing, nitrogen fixing actinorhizal trees such as the Casuarina. The salt tolerance of Casuarina is enhanced by the nitrogen-fixing symbiosis that they form with the actinobacterium Frankia. Identification and molecular characterization of salt-tolerant Casuarina species and associated Frankia is imperative for the successful utilization of Casuarina trees in saline soil reclamation efforts. In this study, salt-tolerant and salt-sensitive Casuarina associated Frankia strains were identified and comparative genomics, transcriptome profiling, and proteomics were employed to elucidate the molecular mechanisms of salt and osmotic stress tolerance. Salt-tolerant Frankia strains (CcI6 and Allo2) that could withstand up to 1000 mM NaCl and a salt-sensitive Frankia strain (CcI3) which could withstand only up to 475 mM NaCl were identified. The remaining isolates had intermediate levels of salt tolerance with MIC values ranging from 650 mM to 750 mM. Comparative genomic analysis showed that all of the Frankia isolates from Casuarina belonged to the same species (Frankia casuarinae). Pangenome analysis revealed a high abundance of singletons among all Casuarina isolates. The two salt-tolerant strains contained 153 shared single copy genes (most of which code for hypothetical proteins) that were not found in the salt-sensitive(CcI3) and moderately salt-tolerant (CeD) strains. RNA-seq analysis of one of the two salt-tolerant strains (Frankia sp. strain CcI6) revealed hundreds of genes differentially expressed under salt and/or osmotic stress. Among the 153 genes, 7 and 7 were responsive to salt and osmotic stress, respectively. Proteomic profiling confirmed the transcriptome results and identified 19 and 8 salt and/or osmotic stress-responsive proteins in the

Biochemical resistance of pyrogenic organic matter in fire-affected mineral soils of Southern Europe

NASA Astrophysics Data System (ADS)

Knicker, H.; González Vila, F. J.; Clemente Salas, L.

2012-04-01

Incorporated into the soil, naturally formed pyrogenic organic matter (PyOM) is considered as highly recalcitrant, but direct estimation of PyOM decomposition rates are scarce. With this aim in mind, we subjected organic matter (OM) of fire-affected and unaffected soils to biochemical degradation under laboratory conditions and monitored CO2 production over a period of seven months. The soils derived from fire affected and unaffected areas of the Sierra de Aznalcóllar and the Doñana National Park, Southern Spain. Virtual fractionation of the solid-state 13C nuclear magnetic resonance (NMR) spectra of the fire affected soils into fire-unaffected soil organic matter (SOM) and PyOM yielded charcoal C contributions of 30 to 50% to the total organic C (Corg) of the sample derived from the Aznalcóllar region. Fitting the respiration data with a double exponential decay model revealed a fast carbon flush during the first three weeks of the experiment. Solid-state 13C NMR spectroscopy evidenced the contribution of aromatic moieties of the PyOM to this initial carbon release and to the biosynthesis of new microbial biomass. The input of PyOM resulted in an increase of the mean residence time (MRT) of the slow OM pool of the soil by a factor of 3 to 4 to approximately 40 years which rises doubts rises doubts about the presumed big influence of PyOM as an additional C-sink in soils. On the other hand, although being small the difference in turnover rates is evident and has some major implication with respect to long-term alteration of the chemical composition of OM in fire-affected soils. Based on the obtained results and the analysis of PyOM in other soil systems, a conceptual model is presented which can explain the different behavior of PyOM under different soil conditions.

Oxygation enhances growth, gas exchange and salt tolerance of vegetable soybean and cotton in a saline vertisol.

PubMed

Bhattarai, Surya P; Midmore, David J

2009-07-01

Impacts of salinity become severe when the soil is deficient in oxygen. Oxygation (using aerated water for subsurface drip irrigation of crop) could minimize the impact of salinity on plants under oxygen-limiting soil environments. Pot experiments were conducted to evaluate the effects of oxygation (12% air volume/volume of water) on vegetable soybean (moderately salt tolerant) and cotton (salt tolerant) in a salinized vertisol at 2, 8, 14, 20 dS/m EC(e). In vegetable soybean, oxygation increased above ground biomass yield and water use efficiency (WUE) by 13% and 22%, respectively, compared with the control. Higher yield with oxygation was accompanied by greater plant height and stem diameter and reduced specific leaf area and leaf Na+ and Cl- concentrations. In cotton, oxygation increased lint yield and WUE by 18% and 16%, respectively, compared with the control, and was accompanied by greater canopy light interception, plant height and stem diameter. Oxygation also led to a greater rate of photosynthesis, higher relative water content in the leaf, reduced crop water stress index and lower leaf water potential. It did not, however, affect leaf Na+ or Cl- concentration. Oxygation invariably increased, whereas salinity reduced the K+ : Na+ ratio in the leaves of both species. Oxygation improved yield and WUE performance of salt tolerant and moderately tolerant crops under saline soil environments, and this may have a significant impact for irrigated agriculture where saline soils pose constraints to crop production.

Effects of spatiotemporal variation of soil salinity on fine root distribution in different plant configuration modes in new reclamation coastal saline field.

PubMed

Jiang, Hong; Du, Hongyu; Bai, Yingying; Hu, Yue; Rao, Yingfu; Chen, Chong; Cai, Yongli

2016-04-01

In order to study the effects of salinity on plant fine roots, we considered three different plant configuration modes (tree stand model (TSM), shrub stand model (SSM), and tree-shrub stand model (TSSM)). Soil samples were collected with the method of soil drilling. Significant differences of electrical conductivity (EC) in the soil depth of 0-60 cm were observed among the three modes (p < 0.05). In the above three modes, the variation of soil salinity among various soil layers and monthly variation of soil salinity were the highest in SSM and reached 2.30 and 2.23 mS/cm (EC1:5), respectively. Due to the effect of salinity, fine root biomass (FRB) showed significant differences in different soil depths (p < 0.05). More than 60% of FRB was concentrated in the soil depth above 30 cm. FRB showed exponential decline with soil depth (p < 0.05). FRB showed spatial heterogeneity in the 40-cm soil depth. In the above three modes, compared with FRB, specific root length (SRL) and fine root length density (FRLD) showed the similar changing trend. Fine roots showed significant seasonal differences among different modes (p < 0.05). FRB showed the bimodal variation and was the highest in July. However, we found that the high content of salts had obvious inhibitory effect on the distribution of FRB. Therefore, the salinity should be below 1.5 mS/cm, which was suitable for the growth of plant roots. Among the three modes, TSSM had the highest FRB, SRL, and FRLD and no obvious soil salt accumulation was observed. The results indicated that fine root biomass was affected by high salt and that TSSM had the strong effects of salt suppression and control. In our study, TSSM may be the optimal configuration mode for salt suppression and control in saline soil.

Spectral Characteristics of Salinized Soils during Microbial Remediation Processes.

PubMed

Ma, Chuang; Shen, Guang-rong; Zhi, Yue-e; Wang, Zi-jun; Zhu, Yun; Li, Xian-hua

2015-09-01

In this study, the spectral reflectance of saline soils, the associated soil salt content (SSC) and the concentrations of salt ions were measured and analysed by tracing the container microbial remediation experiments for saline soil (main salt is sodium chloride) of Dongying City, Shandong Province. The sensitive spectral reflectance bands of saline soils to SSC, Cl- and Na+ in the process of microbial remediation were analysed. The average-dimension reduction of these bands was conducted by using a combination of correlation coefficient and decision coefficient, and by gradually narrowing the sampling interval method. Results showed that the tendency and magnitude of the average spectral reflectance in all bands of saline soils during the total remediation processes were nearly consistent with SSC and with Cl- coocentration, respectively. The degree of salinity of the soil, including SSC and salt ion concentrations, had a significant positive correlation with the spectral reflectance of all bands, particularly in the near-infrared band. The optimal spectral bands of SSC were 1370 to 1445 nm and 1447 to 1608 nm, whereas the optimal spectral bands of Cl- and Na+ were 1336 to 1461 nm and 1471 to 1561 nm, respectively. The relationship model among SSC, soil salt ion concentrations (Cl- and Na+) and soil spectral reflectance of the corresponding optimal spectral band was established. The largest R2 of relationship model between SSC and the average reflectance of associated optimal band reached to 0.95, and RMSEC and RMSEP were 1.076 and 0.591, respectively. Significant statistical analysis of salt factors and soil reflectance for different microbial remediation processes indicated that the spectral response characteristics and sensitivity of SSC to soil reflectance, which implied the feasibility of high spectrum test on soil microbial remediation monitoring, also provided the basis for quick nondestructive monitoring soil bioremediation process by soil spectral

Thallium isotope variations in anthropogenically-affected soils

NASA Astrophysics Data System (ADS)

Vanek, Ales; Chrastny, Vladislav; Penizek, Vit; Mihaljevic, Martin; Komarek, Michael; Cabala, Jerzy

2014-05-01

Our preliminary data from soils impacted by long-term Tl deposition in the vicinity of a primary/secondary Zn smelter at Olkusz (Poland) indicate apparent variability of ɛ205Tl within soil profiles. The identified ɛ205Tl values presented for the forest soil profile reached -1.7 in the surface/organic horizon, +1.9 in the organo-mineral horizon (Ap), and +1.0 in the mineral horizon (C). This finding suggests both the enrichment of 203Tl isotope in the topsoil, as well as its preferential release during smelting operations, as "lighter" Tl tends to enter the emissions during a high-temperature process. The maximum ɛ205Tl value in the subsurface horizon Ap is in accordance with the concentration peak of oxalate-extractable Mn, indicating the presence of amorphous/poorly-crystalline Mn oxides with a potential to isotopically fractionate Tl toward the "heavier" fraction. The Tl isotope signature in the bottom horizon probably reflects the composition of a local geochemical anomaly of Tl. However, a portion of mobile (anthropogenic) Tl with negative ɛ205Tl moving downwards in the soil profile cannot be neglected. In general, there is no detailed information about the biogeochemical cycling and variations of Tl isotopes in areas affected by significant anthropogenic inputs of the metal (e.g., coal burning and primary metallurgy); the questions of the degree to which the factors such as soil (and sediment) chemistry, mineralogy, local biota, and pollution source control Tl isotope fractionation remain unresolved. Therefore, further research on the topic is needed before any principal conclusions will be made.

New Insights on Plant Salt Tolerance Mechanisms and Their Potential Use for Breeding

PubMed Central

Hanin, Moez; Ebel, Chantal; Ngom, Mariama; Laplaze, Laurent; Masmoudi, Khaled

2016-01-01

Soil salinization is a major threat to agriculture in arid and semi-arid regions, where water scarcity and inadequate drainage of irrigated lands severely reduce crop yield. Salt accumulation inhibits plant growth and reduces the ability to uptake water and nutrients, leading to osmotic or water-deficit stress. Salt is also causing injury of the young photosynthetic leaves and acceleration of their senescence, as the Na+ cation is toxic when accumulating in cell cytosol resulting in ionic imbalance and toxicity of transpiring leaves. To cope with salt stress, plants have evolved mainly two types of tolerance mechanisms based on either limiting the entry of salt by the roots, or controlling its concentration and distribution. Understanding the overall control of Na+ accumulation and functional studies of genes involved in transport processes, will provide a new opportunity to improve the salinity tolerance of plants relevant to food security in arid regions. A better understanding of these tolerance mechanisms can be used to breed crops with improved yield performance under salinity stress. Moreover, associations of cultures with nitrogen-fixing bacteria and arbuscular mycorrhizal fungi could serve as an alternative and sustainable strategy to increase crop yields in salt-affected fields. PMID:27965692

Effects of livestock species and stocking density on accretion rates in grazed salt marshes

NASA Astrophysics Data System (ADS)

Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

2015-01-01

Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive accelerated SLR depends on sufficient deposition of sediments which add to vertical marsh accretion. Accretion rate is influenced by a number of factors, and livestock grazing was recently included. Livestock grazing is assumed to reduce accretion rates in two ways: (a) directly by increasing soil compaction through trampling, and (b) indirectly by affecting the vegetation structure, which may lower the sediment deposition. For four years, we studied the impact of two livestock species (horse and cattle) at two stocking densities (0.5 and 1.0 animal ha-1) on accretion in a large-scale grazing experiment using sedimentation plates. We found lower cumulative accretion rates in high stocking densities, probably because more animals cause more compaction and create a lower canopy. Furthermore, a trend towards lower accretion rates in horse-compared to cattle-grazed treatments was found, most likely because (1) horses are more active and thus cause more compaction, and (2) herbage intake by horses is higher than by cattle, which causes a higher biomass removal and shorter canopy. During summer periods, negative accretion rates were found. When the grazing and non-grazing seasons were separated, the impact of grazing differed among years. In summer, we only found an effect of different treatments if soil moisture (precipitation) was relatively low. In winter, a sufficiently high inundation frequency was necessary to create differences between grazing treatments. We conclude that stocking densities, and to a certain extent also livestock species, affect accretion rates in salt marshes. Both stocking densities and livestock species should thus be taken into account in management

Hydrogen Sulfide Regulates Salt Tolerance in Rice by Maintaining Na+/K+ Balance, Mineral Homeostasis and Oxidative Metabolism Under Excessive Salt Stress

PubMed Central

Mostofa, Mohammad G.; Saegusa, Daisuke; Fujita, Masayuki; Tran, Lam-Son Phan

2015-01-01

Being a salt sensitive crop, rice growth and development are frequently affected by soil salinity. Hydrogen sulfide (H2S) has been recently explored as an important priming agent regulating diverse physiological processes of plant growth and development. Despite its enormous prospects in plant systems, the role of H2S in plant stress tolerance is still elusive. Here, a combined pharmacological, physiological and biochemical approach was executed aiming to examine the possible mechanism of H2S in enhancement of rice salt stress tolerance. We showed that pretreating rice plants with H2S donor sodium bisulfide (NaHS) clearly improved, but application of H2S scavenger hypotaurine with NaHS decreased growth and biomass-related parameters under salt stress. NaHS-pretreated salt-stressed plants exhibited increased chlorophyll, carotenoid and soluble protein contents, as well as suppressed accumulation of reactive oxygen species (ROS), contributing to oxidative damage protection. The protective mechanism of H2S against oxidative stress was correlated with the elevated levels of ascorbic acid, glutathione, redox states, and the enhanced activities of ROS- and methylglyoxal-detoxifying enzymes. Notably, the ability to decrease the uptake of Na+ and the Na+/K+ ratio, as well as to balance mineral contents indicated a role of H2S in ion homeostasis under salt stress. Altogether, our results highlight that modulation of the level of endogenous H2S genetically or exogenously could be employed to attain better growth and development of rice, and perhaps other crops, under salt stress. Furthermore, our study reveals the importance of the implication of gasotransmitters like H2S for the management of salt stress, thus assisting rice plants to adapt to adverse environmental changes. PMID:26734015

How grazing affects soil quality of soils formed in the glaciated northeastern United States.

PubMed

Cox, Alissa H; Amador, José A

2018-02-21

Historically, much of the New England landscape was converted to pasture for grazing animals and harvesting hay. Both consumer demand for local sustainably produced food, and the number of small farms is increasing in RI, highlighting the importance of characterizing the effects livestock have on the quality of pasture soils. To assess how livestock affect pasture on Charlton and Canton soils series in RI, we examined soil quality in farms raising beef cattle (Bos taurus), sheep (Ovis aries), and horses (Equus ferus caballus), using hayed pastures as a control. We sampled three pastures per livestock type and three control hayed pastures in May, August, and October 2012. Hay fields and pastures grazed by sheep had statistically significant (P < 0.001) better soil quality than pastures grazed by beef cattle or horses. This was driven by parameters including penetration resistance, bulk density, aggregate stability, and infiltration rate. Hayfields also showed higher soil quality measures than grazed pastures for organic matter content and active C. In addition, significant differences in nitrate and phosphate concentrations were observed among livestock types. Respiration and infiltration rates, pH, and ammonium concentrations, on the other hand, did not differ significantly among pasture types. When all soil quality indicators in this study were weighed equally, soil quality scores followed the order: hay > sheep > beef cattle > horses. The results of our study provide baseline data on the effect different types of livestock have on pasture soil quality in RI, which may be useful in making sound land use and agricultural management decisions.

Inversion of soil electrical conductivity data to estimate layered soil properties

USDA-ARS?s Scientific Manuscript database

CBulk apparent soil electrical conductivity (ECa) sensors respond to multiple soil properties, including clay content, water content, and salt content (i.e., salinity). They provide a single sensor value for an entire soil profile down to a sensor-dependent measurement depth, weighted by a nonlinear...

Mechanisms governing the leaching of soil metals as a result of disposal of olive mill wastewater on agricultural soils.

PubMed

Aharonov-Nadborny, R; Tsechansky, L; Raviv, M; Graber, E R

2018-07-15

Olive mill wastewater (OMWW) is an acidic, saline, and organic matter-rich aqueous byproduct of olive oil production that is usually disposed of by spreading on agricultural soils. This study tested whether spreading OMWW can release indigenous soil metals (Fe, Mn, Cu and Zn) through pH, redox, and DOM complexation-related mechanisms, using three agricultural soils having different textures and chemical properties, and controlled pH and redox conditions (pH5.6 or 8.4; ORP from -200 to +250mV). Comparison treatments included a solution having the same salt content and composition as OMWW but lacking OM, and deionized water (DW). In all three soils and under all pH and redox conditions, the model salt solution and DW treatments solubilized considerably fewer metal cations than did OMWW. Overall, the primary factor in metals release from the soils by OMWW was the DOM fraction. pH, redox and soil type played secondary but important roles in solubilization of the various metals. pH had a major impact on Mn leaching but no impact on Fe and Cu leaching. Conversely, redox did not affect Mn leaching, but lower redox conditions contributed to elevated release of both Fe and Cu. For the most part, released metals were sourced from water soluble, exchangeable, easily reducible, and moderately reducible soil metals pools. Fe, Mn and Cu released from the soils by OMWW featured mainly as metal-organic complexes, and OMWW generally caused Zn precipitation in the soils. Soils rich in clay and organic matter under reduced pH and low redox conditions released substantially more metal cations than did a sand-rich soil. Spreading OMWW may result in sequestration of essential micronutrients like Zn, and increased availability of other micronutrients such as Fe, Mn and Cu. Copyright © 2018 Elsevier B.V. All rights reserved.

Salt modulates gravity signaling pathway to regulate growth direction of primary roots in Arabidopsis.

PubMed

Sun, Feifei; Zhang, Wensheng; Hu, Haizhou; Li, Bao; Wang, Youning; Zhao, Yankun; Li, Kexue; Liu, Mengyu; Li, Xia

2008-01-01

Plant root architecture is highly plastic during development and can adapt to many environmental stresses. The proper distribution of roots within the soil under various conditions such as salinity, water deficit, and nutrient deficiency greatly affects plant survival. Salinity profoundly affects the root system architecture of Arabidopsis (Arabidopsis thaliana). However, despite the inhibitory effects of salinity on root length and the number of roots, very little is known concerning influence of salinity on root growth direction and the underlying mechanisms. Here we show that salt modulates root growth direction by reducing the gravity response. Exposure to salt stress causes rapid degradation of amyloplasts in root columella cells of Arabidopsis. The altered root growth direction in response to salt was found to be correlated with PIN-FORMED2 (PIN2) messenger RNA abundance and expression and localization of the protein. Furthermore, responsiveness to gravity of salt overly sensitive (sos) mutants is substantially reduced, indicating that salt-induced altered gravitropism of root growth is mediated by ion disequilibrium. Mutation of SOS genes also leads to reduced amyloplast degradation in root tip columella cells and the defects in PIN2 gene expression in response to salt stress. These results indicate that the SOS pathway may mediate the decrease of PIN2 messenger RNA in salinity-induced modification of gravitropic response in Arabidopsis roots. Our findings provide new insights into the development of a root system necessary for plant adaptation to high salinity and implicate an important role of the SOS signaling pathway in this process.

How can we take advantage of halophyte properties to cope with heavy metal toxicity in salt-affected areas?

PubMed Central

Lutts, Stanley; Lefèvre, Isabelle

2015-01-01

Background Many areas throughout the world are simultaneously contaminated by high concentrations of soluble salts and by high concentrations of heavy metals that constitute a serious threat to human health. The use of plants to extract or stabilize pollutants is an interesting alternative to classical expensive decontamination procedures. However, suitable plant species still need to be identified for reclamation of substrates presenting a high electrical conductivity. Scope Halophytic plant species are able to cope with several abiotic constraints occurring simultaneously in their natural environment. This review considers their putative interest for remediation of polluted soil in relation to their ability to sequester absorbed toxic ions in trichomes or vacuoles, to perform efficient osmotic adjustment and to limit the deleterious impact of oxidative stress. These physiological adaptations are considered in relation to the impact of salt on heavy metal bioavailabilty in two types of ecosystem: (1) salt marshes and mangroves, and (2) mine tailings in semi-arid areas. Conclusions Numerous halophytes exhibit a high level of heavy metal accumulation and external NaCl may directly influence heavy metal speciation and absorption rate. Maintenance of biomass production and plant water status makes some halophytes promising candidates for further management of heavy-metal-polluted areas in both saline and non-saline environments. PMID:25672360

Unsaturated flow processes in structurally-variable pathways in wildfire-affected soils and ash

NASA Astrophysics Data System (ADS)

Ebel, B. A.

2016-12-01

Prediction of flash flood and debris flow generation in wildfire-affected soils and ash hinges on understanding unsaturated flow processes. Water resources issues, such as groundwater recharge, also rely on our ability to quantify subsurface flow. Soil-hydraulic property data provide insight into unsaturated flow processes and timescales. A literature review and synthesis of existing data from the literature for wildfire-affected soils, including ash and unburned soils, facilitated calculating metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity (S) and the Green-Ampt wetting front parameter (Ψf) were significantly lower in burned soils compared to unburned soils, while field-saturated hydraulic conductivity (Kfs) was not significantly different. The magnitude and duration of the influence of capillarity was substantially reduced in burned soils, leading to faster ponding times in response to rainfall. Ash had large values of S and Kfs compared to unburned and burned soils but intermediate values of Ψf, suggesting that ash has long ponding times in response to rainfall. The ratio of S2/Kfs was nearly constant ( 100 mm) for unburned soils, but was more variable in burned soils. Post-wildfire changes in this ratio suggested that unburned soils had a balance between gravity and capillarity contributions to infiltration, which may depend on soil organic matter, while burning shifted infiltration more towards gravity contributions by reducing S. Taken together, the changes in post-wildfire soil-hydraulic properties increased the propensity for surface runoff generation and may have enhanced subsurface preferential flow through pathways altered by wildfire.

Predicting Soil Salinity with Vis–NIR Spectra after Removing the Effects of Soil Moisture Using External Parameter Orthogonalization

PubMed Central

Liu, Ya; Pan, Xianzhang; Wang, Changkun; Li, Yanli; Shi, Rongjie

2015-01-01

Robust models for predicting soil salinity that use visible and near-infrared (vis–NIR) reflectance spectroscopy are needed to better quantify soil salinity in agricultural fields. Currently available models are not sufficiently robust for variable soil moisture contents. Thus, we used external parameter orthogonalization (EPO), which effectively projects spectra onto the subspace orthogonal to unwanted variation, to remove the variations caused by an external factor, e.g., the influences of soil moisture on spectral reflectance. In this study, 570 spectra between 380 and 2400 nm were obtained from soils with various soil moisture contents and salt concentrations in the laboratory; 3 soil types × 10 salt concentrations × 19 soil moisture levels were used. To examine the effectiveness of EPO, we compared the partial least squares regression (PLSR) results established from spectra with and without EPO correction. The EPO method effectively removed the effects of moisture, and the accuracy and robustness of the soil salt contents (SSCs) prediction model, which was built using the EPO-corrected spectra under various soil moisture conditions, were significantly improved relative to the spectra without EPO correction. This study contributes to the removal of soil moisture effects from soil salinity estimations when using vis–NIR reflectance spectroscopy and can assist others in quantifying soil salinity in the future. PMID:26468645

Heavy metal interaction for Andropogon scoparius and Rudbeckia hirta grown on soil from urban and rural sites with heavy metals additions

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

Miles, L.J.; Parker, G.R.

1979-10-01

Little bluestem (Andropogon scoparius) and black-eyed Susan (Rudbeckia hirta) were grown in two soils with all combinations of Cd, Zn, Pb, and Cu at two levels each for 12 weeks. Germination and establishment were completely retarded by the addition of 1000 ..mu..g/g Zn as ZnCl/sub 2/, which was due to a salt effect. Neither Cd nor Cu additions affected germination. A slight decrease in germination was noted for Pb additions of 900 ..mu..g/g which may also be associated with a salt effect. Cadmium at 10- and 20-..mu..g/g addition rates did not affect top or root dry weight. Lead and Cumore » additions reduced shoot and root dry weight yields of Andropogon scoparius, root weights being more severely affected than shoot weights. Metal additions to the urban site soil did not reduce yields to the extent they did on the rural site soil. However, yields on the urban site soil control treatment were lower compared to those for the rural site control treatment. DTPA extraction levels of heavy metals were not well correlated to plant concentrations for comparisons between the two soils. It was concluded that DTPA soil extraction may not be acceptable for metal availability comparisons among soils of differing pH. Circumstantial evidence was found for both synergistic and antagonistic effects among the heavy metals. These were of a low level and no consistent response could be determined over species or soils.« less

Salt marsh dieback in coastal Louisiana: survey of plant and soil conditions in Barataria and Terrebonne basins, June 2000-September 2001

USGS Publications Warehouse

McKee, Karen L.; Mendelssohn, Irving A.; Materne, Michael D.

2006-01-01

Sudden and extensive dieback of the perennial marsh grass, Spartina alterniflora Loisel (smooth cordgrass), which dominates regularly flooded salt marshes along the Gulf of Mexico and Atlantic coastlines, occurred in the coastal zone of Louisiana. The objectives of this study were to assess soil and plant conditions in dieback areas of the Barataria-Terrebonne estuarine system as well as vegetative recovery during and after this dieback event. Multiple dieback sites were examined along 100 km of shoreline from the Atchafalaya River to the Mississippi River during the period from June 2000 through September 2001. The species primarily affected was S. alterniflora; sympatric species such as Avicennia germinans (L.) Stearn (black mangrove) and Juncus roemerianus Scheele (needlegrass rush) showed no visible signs of stress. The pattern of marsh dieback was distinctive with greatest mortality in the marsh interior, suggesting a correlation with local patterns of soil chemistry and/or hydrology. Little or no expansion of dieback occurred subsequent to the initial event, and areas with 50 percent or less mortality in the fall of 2000 had completely recovered by April 2001. Recovery was slower in interior marshes with 90 percent or greater mortality initially. However, regenerating plants in dieback areas showing some recovery were robust, and reproductive output was high, indicating that the causative agent was no longer present and that post-dieback soil conditions were actually promoting plant growth. Stands of other species within or near some dieback sites remained largely unchanged or expanded (A. germinans) into the dead salt marsh. The cause of the dieback is currently unknown. Biotic agents and excessive soil waterlogging/high sulfide were ruled out as primary causes of this acute event, although they could have contributed to overall plant stress and/or interacted with the primary agent to cause plant mortality. Our observations over the 15 month study

Contents and composition of organic matter in subsurface soils affected by land use and soil mineralogy

NASA Astrophysics Data System (ADS)

Ellerbrock, Ruth H.; Kaiser, Michael

2010-05-01

Land use and mineralogy affect the ability of surface as well as subsurface soils to sequester organic carbon and their contribution to mitigate the greenhouse effect. This study aimed to investigate the long-term impact of land use (i.e., arable and forest) and soil mineralogy on contents and composition of soil organic matter (SOM) from subsurface soils. Seven soils different in mineralogy (Albic and Haplic Luvisol, Colluvic and Haplic Regosol, Haplic and Vertic Cambisol, Haplic Stagnosol) were selected within Germany. Soil samples were taken from forest and adjacent arable sites. First, particulate and water soluble organic matter were separated from the subsurface soil samples. From the remaining solid residues the OM(PY) fractions were separated, analyzed for its OC content (OCPY) and characterized by FTIR spectroscopy. For the arable subsurface soils multiple regression analyses indicate significant positive relationships between the soil organic carbon contents and the contents of i) exchangeable Ca and oxalate soluble Fe, and Alox contents. Further for the neutral arable subsurface soils the contents OCPY weighted by its C=O contents were found to be related to the contents of Ca indicating interactions between OM(PY) and Ca cations. For the forest subsurface soils (pH <5) the OCPY contents were positively related with the contents of Na-pyrophosphate soluble Fe and Al. For the acidic forest subsurface soils such findings indicate interactions between OM(PY) and Fe3+ and Al3+ cations. The effects of land use and soil mineralogy on contents and composition of SOM and OM(PY) will be discussed.

Microbial biodiversity in arable soils is affected by agricultural practices

NASA Astrophysics Data System (ADS)

Wolińska, Agnieszka; Górniak, Dorota; Zielenkiewicz, Urszula; Goryluk-Salmonowicz, Agata; Kuźniar, Agnieszka; Stępniewska, Zofia; Błaszczyk, Mieczysław

2017-04-01

The aim of the study was to examine the differences in microbial community structure as a result of agricultural practices. Sixteen samples of cultivated and the same number of non-cultivated soils were selected. Gel bands were identified using the GelCompar software to create the presence-absence matrix, where each band represented a bacterial operational taxonomic unit. The data were used for principal-component analysis and additionally, the Shannon- Weaver index of general diversity, Simpson index of dominance and Simpson index of diversity were calculated. Denaturing gradient gel electrophoresis profiles clearly indicated differentiation of tested samples into two clusters: cultivated and non-cultivated soils. Greater numbers of dominant operational taxonomic units (65) in non-cultivated soils were noted compared to cultivated soils (47 operational taxonomic units). This implies that there was a reduction of dominant bacterial operational taxonomic units by nearly 30% in cultivated soils. Simpson dominance index expressing the number of species weighted by their abundance amounted to 1.22 in cultivated soils, whereas a 3-fold higher value (3.38) was observed in non-cultivated soils. Land-use practices seemed to be a important factors affected on biodiversity, because more than soil type determined the clustering into groups.

How internal drainage affects evaporation dynamics from soil surfaces ?

NASA Astrophysics Data System (ADS)

Or, D.; Lehmann, P.; Sommer, M.

2017-12-01

Following rainfall, infiltrated water may be redistributed internally to larger depths or lost to the atmosphere by evaporation (and by plant uptake from depths at longer time scales). A large fraction of evaporative losses from terrestrial surfaces occurs during stage1 evaporation during which phase change occurs at the wet surface supplied by capillary flow from the soil. Recent studies have shown existence of a soil-dependent characteristic length below which capillary continuity is disrupted and a drastic shift to slower stage 2 evaporation ensues. Internal drainage hastens this transition and affect evaporative losses. To predict the transition to stage 2 and associated evaporative losses, we developed an analytical solution for evaporation dynamics with concurrent internal drainage. Expectedly, evaporative losses are suppressed when drainage is considered to different degrees depending on soil type and wetness. We observe that high initial water content supports rapid drainage and thus promotes the sheltering of soil water below the evaporation depth. The solution and laboratory experiments confirm nonlinear relationship between initial water content and total evaporative losses. The concept contributes to establishing bounds on regional surface evaporation considering rainfall characteristics and soil types.

Litter decay controlled by temperature, not soil properties, affecting future soil carbon.

PubMed

Gregorich, Edward G; Janzen, Henry; Ellert, Benjamin H; Helgason, Bobbi L; Qian, Budong; Zebarth, Bernie J; Angers, Denis A; Beyaert, Ronald P; Drury, Craig F; Duguid, Scott D; May, William E; McConkey, Brian G; Dyck, Miles F

2017-04-01

Widespread global changes, including rising atmospheric CO 2 concentrations, climate warming and loss of biodiversity, are predicted for this century; all of these will affect terrestrial ecosystem processes like plant litter decomposition. Conversely, increased plant litter decomposition can have potential carbon-cycle feedbacks on atmospheric CO 2 levels, climate warming and biodiversity. But predicting litter decomposition is difficult because of many interacting factors related to the chemical, physical and biological properties of soil, as well as to climate and agricultural management practices. We applied 13 C-labelled plant litter to soil at ten sites spanning a 3500-km transect across the agricultural regions of Canada and measured its decomposition over five years. Despite large differences in soil type and climatic conditions, we found that the kinetics of litter decomposition were similar once the effect of temperature had been removed, indicating no measurable effect of soil properties. A two-pool exponential decay model expressing undecomposed carbon simply as a function of thermal time accurately described kinetics of decomposition. (R 2  = 0.94; RMSE = 0.0508). Soil properties such as texture, cation exchange capacity, pH and moisture, although very different among sites, had minimal discernible influence on decomposition kinetics. Using this kinetic model under different climate change scenarios, we projected that the time required to decompose 50% of the litter (i.e. the labile fractions) would be reduced by 1-4 months, whereas time required to decompose 90% of the litter (including recalcitrant fractions) would be reduced by 1 year in cooler sites to as much as 2 years in warmer sites. These findings confirm quantitatively the sensitivity of litter decomposition to temperature increases and demonstrate how climate change may constrain future soil carbon storage, an effect apparently not influenced by soil properties. © 2016 Her Majesty

Response of Methylocystis sp. Strain SC2 to Salt Stress: Physiology, Global Transcriptome, and Amino Acid Profiles.

PubMed

Han, Dongfei; Link, Hannes; Liesack, Werner

2017-08-11

changes in moisture content and soil salinity. Growth and methane oxidation of Methylocystis sp. strain SC2 was not affected by the presence of 0.5% NaCl, while 1% NaCl completely inhibited its activities. This places strain SC2 into the low salt tolerance range reported for other Methylocystis spp. Our results show that, albeit in a narrow range, strain SC2 is able to respond and adapt to salinity changes. It possesses various stress-response mechanisms, which allows for a full resumption of its activities within 23.5 hours when exposed to 0.75% NaCl. Presumably, these mechanisms allow Methylocystis spp., such as strain SC2, to thrive in upland soils and to adapt to certain fluctuations in soil salinity. Copyright © 2017 American Society for Microbiology.

Effect of exchangeable cation concentration on sorption and desorption of dissolved organic carbon in saline soils.

PubMed

Setia, Raj; Rengasamy, Pichu; Marschner, Petra

2013-11-01

Sorption is a very important factor in stabilization of dissolved organic carbon (DOC) in soils and thus C sequestration. Saline soils have significant potential for C sequestration but little is known about the effect of type and concentration of cations on sorption and release of DOC in salt-affected soils. To close this knowledge gap, three batch sorption and desorption experiments were conducted using soils treated with solutions either low or high in salinity. In Experiment 1, salinity was developed with either NaCl or CaCl2 to obtain an electrical conductivity (EC) in a 1:5 soil: water extract (EC1:5) of 2 and 4 dS m(-1). In Experiments 2 and 3, NaCl and CaCl2 were added in various proportions (between 25 and 100%) to obtain an EC1:5 of 0.5 and 4 dS m(-1), respectively. At EC1:5 of 4 dS m(-1), the sorption of DOC (derived from wheat straw) was high even at a low proportion of added Ca(2+) and did not change with proportion of Ca added, but at EC1:5 of 0.5 dS m(-1) increasing proportion of Ca(2+) added increased DOC sorption. This can be explained by the differences in exchangeable Ca(2+) at the two salinity levels. At EC1:5 of 4 dS m(-1), the exchangeable Ca(2+) concentration did not increase beyond a proportion of 25% Ca(2+), whereas it increased with increasing Ca(2+) proportion in the treatments at EC1:5 of 0.5 dS m(-1). The DOC sorption was lowest with a proportion of 100% as Na(+). When Ca(2+) was added, DOC sorption was highest, but least was desorbed (with deionised water), thus sorption and desorption of added DOC were inversely related. The results of this study suggest that DOC sorption in salt-affected soils is mainly controlled by the levels of exchangeable Ca(2+) irrespective of the Ca(2+) concentration in the soil solution which has implications on carbon stabilization in salt-affected soils. Copyright © 2013 Elsevier B.V. All rights reserved.

Linking hydraulic properties of fire-affected soils to infiltration and water repellency

USGS Publications Warehouse

Moody, John A.; David Kinner,; Xavier Úbeda,

2009-01-01

Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, Kf and (2) sorptivity, S(θi), as a function of initial soil moisture content, θi, ranging from extremely dry conditions (θi < 0.02 cm3 cm−3) to near saturation. In the field and in the laboratory replicate measurements were made of ash, reference soils, soils unaffected by fire, and fire-affected soils. Each has a different degrees of water repellency that influences Kf and S(θi).Values of Kf ranged from 4.5 × 10−3 to 53 × 10−3 cm s−1 for ash; from 0.93 × 10−3 to 130 × 10−3 cm s−1 for reference soils; and from 0.86 × 10−3 to 3.0 × 10−3 cm s−1, for soil unaffected by fire, which had the lowest values of Kf. Measurements indicated that S(θi) could be represented by an empirical non-linear function of θi with a sorptivity maximum of 0.18–0.20 cm s−0.5, between 0.03 and 0.08 cm3 cm−3. This functional form differs from the monotonically decreasing non-linear functions often used to represent S(θi) for rainfall–runoff modeling. The sorptivity maximum may represent the combined effects of gravity, capillarity, and adsorption in a transitional domain corresponding to extremely dry soil, and moreover, it may explain the observed non-linear behavior, and the critical soil-moisture threshold of water repellent soils. Laboratory measurements of Kf and S(θi) are the first for ash and fire-affected soil, but additional measurements are needed of these hydraulic properties for in situ fire-affected soils. They provide insight into water repellency behavior and infiltration under extremely dry conditions. Most importantly

Soil pollution by petroleum products, III. Kerosene stability in soil columns as affected by volatilization

NASA Astrophysics Data System (ADS)

Galin, Ts.; Gerstl, Z.; Yaron, B.

1990-05-01

The stability of kerosene in soils as affected by volatization was determined in a laboratory column experiment by following the losses in the total concentration and the change in composition of the residuals in a dune sand, a loamy sand, and a silty loam soil during a 50-day period. Seven major compounds ranging between C 9 and C 15 were selected from a large variety of hydrocarbons forming kerosene and their presence in the remaining petroleum product was determined. The change in composition of kerosene during the experimental period was determined by gas chromatography and related to the seven major compounds selected. The experimental conditions — air-dairy soil and no subsequent addition of water—excluded both biodegradative and leaching. losses. The losses of kerosene in air-dried soil columns during the 50-day experimental period and the changes in the composition of the remaining residues due to volatilization are reported. The volatilization of all the components determined was greater from the dune sand and loamy sand soils than from the silty loam soil. It was assumed that the reason for this behavior was that the dune sand and the loamy sand soils contain a greater proportion of large pores (>4.5 μm) than the silty loam soil, even though the total porosity of the loamy sand and the silty loam is similar. In all the soils in the experiment, the components with a high carbon number formed the main fraction of the kerosene residues after 50 days of incubation.

Sorption interactions of organic compounds with soils affected by agricultural olive mill wastewater.

PubMed

Keren, Yonatan; Borisover, Mikhail; Bukhanovsky, Nadezhda

2015-11-01

The organic compound-soil interactions may be strongly influenced by changes in soil organic matter (OM) which affects the environmental fate of multiple organic pollutants. The soil OM changes may be caused by land disposal of various OM-containing wastes. One unique type of OM-rich waste is olive mill-related wastewater (OMW) characterized by high levels of OM, the presence of fatty aliphatics and polyphenolic aromatics. The systematic data on effects of the land-applied OMW on organic compound-soil interactions is lacking. Therefore, aqueous sorption of simazine and diuron, two herbicides, was examined in batch experiments onto three soils, including untreated and OMW-affected samples. Typically, the organic compound-soil interactions increased following the prior land application of OMW. This increase is associated with the changes in sorption mechanisms and cannot be attributed solely to the increase in soil organic carbon content. A novel observation is that the OMW application changes the soil-sorbent matrix in such a way that the solute uptake may become cooperative or the existing ability of a soil sorbent to cooperatively sorb organic molecules from water may become characterized by a larger affinity. The remarkable finding of this study was that in some cases a cooperative uptake of organic molecules by soils makes itself evident in distinct sigmoidal sorption isotherms rarely observed in soil sorption of non-ionized organic compounds; the cooperative herbicide-soil interactions may be characterized by the Hill model coefficients. However, no single trend was found for the effect of applied OMW on the mechanisms of organic compound-soil interactions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stress adaptations in a Plant Growth Promoting Rhizobacterium (PGPR) with increasing salinity in the coastal agricultural soils.

PubMed

Paul, Diby; Nair, Sudha

2008-10-01

The costs associated with soil salinity are potentially enormous and the effects of salinity may impact heavily on agriculture, biodiversity and the environment. As the saline areas under agriculture are increasing every year across the globe, it is of much public concern. Agricultural crops and soil microorganisms are affected with salinity. As Plant Growth Promoting Rhizobacteria (PGPR) have been reported to be contributing to the plant health, the osmotolerance mechanisms of these PGPRs are of importance. Pseudomonas fluorescens MSP-393 is a proven biocontrol agent for many of the crops grown in saline soils of coastal ecosystem. Studies revealed that the root colonization potential of the strain was not hampered with higher salinity in soil. As a means of salt tolerance, the strain de novo -synthesized, the osmolytes, Ala, Gly, Glu, Ser, Thr, and Asp in their cytosol. To understand the mechanism of salt tolerance, the proteome analysis of the bacteria was carried out employing 2D gel electrophoresis and MALDI-TOF. Peptide mass fingerprinting and in silico investigation revealed the up regulation of many of salt regulated proteins. It could be ascertained that the osmotolerance mechanisms of MSP-393 viz. de novo synthesis of osmolytes and over production of salt stress proteins effectively nullified the detrimental effects of high osmolarity. MSP-393 could serve as a suitable bioinoculant for crops grown in saline soils. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Living in Salt: The formation and development of extremophile habitats and biosignatures within salt crusts of the hyperarid Atacama Desert

NASA Astrophysics Data System (ADS)

Finstad, K. M.; Amundson, R.

2013-12-01

It has become increasing apparent that salt-rich deposits are present on the Martian surface and that aqueous alteration has occurred sometime during the planet's past. In the hyperarid Atacama Desert in Chile, an important Earth-based analogue to Mars, microbial life has been discovered inhabiting halite (NaCl) surface crust deposits. Is it possible that similar salt deposits on Mars once harbored microbial life? If so, what adaptations were likely necessary for survival in such an environment and what biosignatures are expected to remain? Although this fascinating ecosystem in the Atacama Desert has been recognized, neither the physical processes of halite crust formation, nor the microorganisms residing within the salts have been extensively studied. To better understand the formation and geochemical dynamics of this unique habitat, we chose two sites within the Atacama Desert which exhibit both active crust formation as well as the presence of microbial communities: one site is on a dry Holocene age lake bed, while the other is of Pleistocene age. At each site soil profiles were excavated and total geochemical analyses were performed. Field observations clearly showed that the soils exhibited transitions of carbonate to sulfate to chloride salt deposition with decreasing depth, and that the thickness and mass of halite in the surficial crust was related to the age of the soil. Isotope profiles of carbon, nitrogen, and sulfur from these soils were also analyzed. Once exposed to the atmosphere, the halite crusts reside in a dynamic state of dissolution and erosion by wind and fog, and reformation due to fog and dew. In the crust nodules, microbial communities were sampled, in centimeter increments from the surface, for carbon, nitrogen, and sulfur isotope/concentration profiles. Our analyses help elucidate the physical and geochemical processes linked to the formation and evolution of these dynamic salt crusts, and the imprint of microbial life within them. A

Soil Tillage Management Affects Maize Grain Yield by Regulating Spatial Distribution Coordination of Roots, Soil Moisture and Nitrogen Status.

PubMed

Wang, Xinbing; Zhou, Baoyuan; Sun, Xuefang; Yue, Yang; Ma, Wei; Zhao, Ming

2015-01-01

The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0-20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20-30 cm layer. Soil moisture in the 20-50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20-50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants' ability to access nutrients and water. An optimal

Soil Tillage Management Affects Maize Grain Yield by Regulating Spatial Distribution Coordination of Roots, Soil Moisture and Nitrogen Status

PubMed Central

Wang, Xinbing; Zhou, Baoyuan; Sun, Xuefang; Yue, Yang; Ma, Wei; Zhao, Ming

2015-01-01

The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0–20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20–30 cm layer. Soil moisture in the 20–50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20–50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants’ ability to access nutrients and water. An

[Accumulation characteristics of applied cinnamic acid in cucumber seedling-soil system under NaCl stress].

PubMed

Wang, Ying; Wu, Feng-Zhi; Wang, Yu-Yan

2011-11-01

Taking cucumber cultivars' Jinlv No. 5' (salt-tolerant) and 'Jinyou No. 1' (salt-sensitive) as test materials, a pot experiment was conducted to study the effects of applying cinnamic acid on the accumulation of applied cinnamic acid in cucumber seedling-soil system under NaCl (585 mg x kg(-1) soil) stress. The concentration of applied cinnamic acid was the main factor affecting the accumulation of the exogenous cinnamic acid in the cucumber plant and soil. With the increasing concentration of applied cinnamic acid, except in the treatment of highest concentration (200 mg x kg(-1) soil) cinnamic acid, the total content of cinnamic acid in cucumber plant was increased. NaCl stress enhanced the toxicity of cinnamic acid. In the treatments of low and medium concentration cinnamic acid, the cinnamic acid content in cucumber plant increased; whereas in the treatments of high concentration cinnamic acid, the decline of the seedlings growth was observed, and led to the decrease of the cinnamic acid content in the plant. The content of cinnamic acid in 'Jinlv No. 5' plant decreased at the concentration of applied cinnamic acid being > 200 mg x kg(-1) soil, while that in 'Jinyou No. 1' started to decrease when the concentration of applied cinnamic acid was > 100 mg x kg(-1) soil, reflecting the discrepancy in salt tolerance of the two cultivars. For the cucumber plant, its leaf had the highest content of cinnamic acid. In the cucumber seedling-soil system, most of applied cinnamic acid was mainly accumulated in soil.

[Effect of shifting sand burial on evaporation reduction and salt restraint under saline water irrigation in extremely arid region].

PubMed

Zhang, Jian-Guo; Zhao, Ying; Xu, Xin-Wen; Lei, Jia-Qiang; Li, Sheng-Yu; Wang, Yong-Dong

2014-05-01

The Taklimakan Desert Highway Shelterbelt is drip-irrigated with high saline groundwater (2.58-29.70 g x L(-1)), and shifting sand burial and water-salt stress are most common and serious problems in this region. So it is of great importance to study the effect of shifting sand burial on soil moisture evaporation, salt accumulation and their distribution for water saving, salinity restraint, and suitable utilization of local land and water resources. In this study, Micro-Lysimeters (MLS) were used to investigate dynamics of soil moisture and salt under different thicknesses of sand burial (1, 2, 3, 4, and 5 cm), and field control experiments of drip-irrigation were also carried out to investigate soil moisture and salt distribution under different thicknesses of shifting sand burial (5, 10, 15, 20, 25, 30, 35, and 40 cm). The soil daily and cumulative evaporation decreased with the increase of sand burial thickness in MLS, cumulative evaporation decreased by 2.5%-13.7% compared with control. And evaporative inhibiting efficiency increased with sand burial thickness, evaporative inhibiting efficiency of 1-5 cm sand burial was 16.7%-79.0%. Final soil moisture content beneath the interface of sand burial increased with sand burial thickness, and it increased by 2.5%-13.7% than control. The topsoil EC of shifting sand in MLS decreased by 1.19-6.00 mS x cm(-1) with the increasing sand burial thickness, whereas soil salt content beneath the interface in MLS increased and amplitude of the topsoil salt content was higher than that of the subsoil. Under drip-irrigation with saline groundwater, average soil moisture beneath the interface of shifting sand burial increased by 0.4% -2.0% compare with control, and the highest value of EC was 7.77 mS x cm(-1) when the sand burial thickness was 10 cm. The trend of salt accumulation content at shifting sand surface increased firstly, and then decreased with the increasing sand burial thickness. Soil salt contents beneath the

How Do Changes to the Railroad Causeway in Utah's Great Salt Lake Affect Water and Salt Flow?

PubMed

White, James S; Null, Sarah E; Tarboton, David G

2015-01-01

Managing terminal lake elevation and salinity are emerging problems worldwide. We contribute to terminal lake management research by quantitatively assessing water and salt flow for Utah's Great Salt Lake. In 1959, Union Pacific Railroad constructed a rock-filled causeway across the Great Salt Lake, separating the lake into a north and south arm. Flow between the two arms was limited to two 4.6 meter wide rectangular culverts installed during construction, an 88 meter opening (referred to locally as a breach) installed in 1984, and the semi porous material of the causeway. A salinity gradient developed between the two arms of the lake over time because the south arm receives approximately 95% of the incoming streamflow entering Great Salt Lake. The north arm is often at, or near, salinity saturation, averaging 317 g/L since 1966, while the south is considerably less saline, averaging 142 g/L since 1966. Ecological and industrial uses of the lake are dependent on long-term salinity remaining within physiological and economic thresholds, although optimal salinity varies for the ecosystem and between diverse stakeholders. In 2013, Union Pacific Railroad closed causeway culverts amid structural safety concerns and proposed to replace them with a bridge, offering four different bridge designs. As of summer 2015, no bridge design has been decided upon. We investigated the effect that each of the proposed bridge designs would have on north and south arm Great Salt Lake elevation and salinity by updating and applying US Geological Survey's Great Salt Lake Fortran Model. Overall, we found that salinity is sensitive to bridge size and depth, with larger designs increasing salinity in the south arm and decreasing salinity in the north arm. This research illustrates that flow modifications within terminal lakes cannot be separated from lake salinity, ecology, management, and economic uses.

Tillage system affects microbiological properties of soil

NASA Astrophysics Data System (ADS)

Delgado, A.; de Santiago, A.; Avilés, M.; Perea, F.

2012-04-01

Soil tillage significantly affects organic carbon accumulation, microbial biomass, and subsequently enzymatic activity in surface soil. Microbial activity in soil is a crucial parameter contributing to soil functioning, and thus a basic quality factor for soil. Since enzymes remain soil after excretion by living or disintegrating cells, shifts in their activities reflect long-term fluctuations in microbial biomass. In order to study the effects of no-till on biochemical and microbiological properties in comparison to conventional tillage in a representative soil from South Spain, an experiment was conducted since 1982 on the experimental farm of the Institute of Agriculture and Fisheries Research of Andalusia (IFAPA) in Carmona, SW Spain (37o24'07''N, 5o35'10''W). The soil at the experimental site was a very fine, montomorillonitic, thermic Chromic Haploxerert (Soil Survey Staff, 2010). A randomized complete block design involving three replications and the following two tillage treatments was performed: (i) Conventional tillage, which involved mouldboard plowing to a depth of 50 cm in the summer (once every three years), followed by field cultivation to a depth of 15 cm before sowing; crop residues being burnt, (ii) No tillage, which involved controlling weeds before sowing by spraying glyphosate and sowing directly into the crop residue from the previous year by using a planter with double-disk openers. For all tillage treatments, the crop rotation (annual crops) consisted of winter wheat, sunflower, and legumes (pea, chickpea, or faba bean, depending on the year), which were grown under rainfed conditions. Enzymatic activities (ß-glucosidase, dehydrogenase, aryl-sulphatase, acid phosphatase, and urease), soil microbial biomass by total viable cells number by acridine orange direct count, the density of cultivable groups of bacteria and fungi by dilution plating on semi-selective media, the physiological profiles of the microbial communities by BiologR, and the

Deposition, Accumulation, and Alteration of Cl(-), NO3(-), ClO4(-) and ClO3(-) Salts in a Hyper-Arid Polar Environment: Mass Balance and Isotopic Constraints

NASA Technical Reports Server (NTRS)

Jackson, Andrew; Davila, Alfonso F.; Boehlke, J. K.; Sturchio, Neil C.; Sevanthi, Ritesh; Estrada, Nubia; Brundrette, Megan; Lacell, Denis; McKay, Christopher P.; Poghosyan, Armen;

Deposition, accumulation, and alteration of Cl-, NO3-, ClO4- and ClO3- salts in a hyper-arid polar environment: Mass balance and isotopic constraints

NASA Astrophysics Data System (ADS)

Jackson, Andrew; Davila, Alfonso F.; Böhlke, John Karl; Sturchio, Neil C.; Sevanthi, Ritesh; Estrada, Nubia; Brundrett, Maeghan; Lacelle, Denis; McKay, Christopher P.; Poghosyan, Armen; Pollard, Wayne; Zacny, Kris

2016-06-01

The salt fraction in permafrost soils/sediments of the McMurdo Dry Valleys (MDV) of Antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction. Previous analyses of the salt fraction in MDV permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stratospheric sources. We expand upon this work by evaluating permafrost soil/sediments in University Valley, located in the ultraxerous zone where both liquid water transport and marine influences are minimal. We determined the abundances of Cl-, NO3-, ClO4- and ClO3- in dry and ice-cemented soil/sediments, snow and glacier ice, and also characterized Cl- and NO3- isotopically. The data are not consistent with salt deposition in a sublimation till, nor with nuclear weapon testing fall-out, and instead point to a dominantly stratospheric source and to varying degrees of post depositional transformation depending on the substrate, from minimal alteration in bare soils to significant alteration (photodegradation and/or volatilization) in snow and glacier ice. Ionic abundances in the dry permafrost layer indicate limited vertical transport under the current climate conditions, likely due to percolation of snowmelt. Subtle changes in ClO4-/NO3- ratios and NO3- isotopic composition with depth and location may reflect both transport related fractionation and depositional history. Low molar ratios of ClO3-/ClO4- in surface soils compared to deposition and other arid systems suggest significant post depositional loss of ClO3-, possibly due to reduction by iron minerals, which may have important implications for oxy-chlorine species on Mars. Salt accumulation varies with distance along the valley and apparent accumulation times based on multiple methods range from ∼10 to 30 kyr near the glacier to 70-200 kyr near the valley mouth. The relatively young age of the salts and

Antioxidant enzyme and osmotic adjustment changes in bean seedlings as affected by biochar under salt stress.

PubMed

Farhangi-Abriz, Salar; Torabian, Shahram

2017-03-01

Salinity damaged cellular membranes through overproduction of reactive oxygen species (ROS), while osmolytes and antioxidant capacities play a vital role in protecting plants from salinity caused oxidative damages. Biochar also could alleviate the negative impacts of salt stress in crops. The pot experiment was conducted to investigate the effects of biochar on some antioxidant enzyme activities and osmolyte adjustments of common bean (Phaseolus vulgaris L. cv. Derakhshan) under salinity stress. Bean plants were subjected to three salinity levels (non-saline, 6 and 12 dSm -1 of NaCl) and biochar treatments (non-biochar, 10% and 20% total pot mass). Shoot and root dry weights of bean were decreased at two salt stress treatments. Salinity increased the activity of catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), polyphenol oxidase (PPO) and superoxide dismutase (SOD), and the content of malondialdehyde (MDA), oxygen radicals (O 2•- ), and hydrogen peroxide (H 2 O 2 ) in leaf and root compared to control. Additionally, increased magnitudes of proline, glycine betaine, soluble sugar and soluble protein contents were more pronounced under 12 dSm -1 NaCl than those under 6 dSm -1 NaCl. In contrast, biochar applied to soil enhanced the shoot and root dry weight in comparison with the non-biochar treatment. Furthermore, all of the antioxidant activities of seedlings in soil treated with biochar, particularly at 20% biochar, declined. With the addition of biochar, the contents of MDA, O 2•- and H 2 O 2 displayed remarkable decrease, and the osmotic substances accumulation in leaves and roots also reduced. The presented results supported the view that biochar can contribute to protect common bean seedlings against NaCl stress by alleviating the oxidative stress. Copyright © 2016 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Transgenic Overexpression of Abcb11 Enhances Biliary Bile Salt Outputs, But Does Not Affect Cholesterol Cholelithogenesis in Mice

PubMed Central

Wang, Helen H.; Lammert, Frank; Schmitz, Anne; Wang, David Q.-H.

2010-01-01

Background Cholesterol gallstone disease is a complex genetic trait and induced by multiple but as yet unknown genes. A major Lith gene, Lith1 was first identified on chromosome 2 in gallstone-susceptible C57L mice compared with resistant AKR mice. Abcb11, encoding the canalicular bile salt export pump in the hepatocyte, co-localizes with the Lith1 QTL region and its hepatic expression is significantly higher in C57L mice than in AKR mice. Material and methods To investigate whether Abcb11 influences cholesterol gallstone formation, we created an Abcb11 transgenic strain on the AKR genetic background and fed these mice with a lithogenic diet for 56 days. Result We excluded functionally relevant polymorphisms of the Abcb11 gene and its promoter region between C57L and AKR mice. Overexpression of Abcb11 significantly promoted biliary bile salt secretion and increased circulating bile salt pool size and bile salt-dependent bile flow rate. However, biliary cholesterol and phospholipid secretion, as well as gallbladder size and contractility were comparable in transgenic and wild-type mice. At 56 days on the lithogenic diet, cholesterol saturation indexes of gallbladder biles and gallstone prevalence rates were essentially similar in these two groups of mice. Conclusion Overexpression of Abcb11 augments biliary bile salt secretion, but does not affect cholelithogenesis in mice. PMID:20456485

Comparative 2D-DIGE analysis of salinity responsive microsomal proteins from leaves of salt-sensitive Arabidopsis thaliana and salt-tolerant Thellungiella salsuginea.

PubMed

Vera-Estrella, Rosario; Barkla, Bronwyn J; Pantoja, Omar

2014-12-05

Halophytes have evolved unique molecular strategies to overcome high soil salinity but we still know very little about the main mechanisms that these plants use to complete their lifecycle under salinity stress. One useful approach to further our understanding in this area is to directly compare the response to salinity of two closely related species which show diverse levels of salt tolerance. Here we present a comparative proteomic study using DIGE of leaf microsomal proteins to identify salt-responsive membrane associated proteins in Arabidopsis thaliana (a glycophyte) and Thellungiella salsuginea (a halophyte). While a small number of distinct protein abundance changes were observed upon salt stress in both species, the most notable differences were observed between species and specifically, in untreated plants with a total of 36 proteins displaying significant abundance changes. Gene ontology (GO) term enrichment analysis showed that the majority of these proteins were distributed into two functional categories; transport (31%) and carbohydrate metabolism (17%). Results identify several novel salt responsive proteins in this system and support the theory that T. salsuginea shows a high degree of salt-tolerance because molecular mechanisms are primed to deal with the stress. This intrinsic ability to anticipate salinity stress distinguishes it from the glycophyte A. thaliana. There is significant interest in understanding the molecular mechanisms that plants use to tolerate salinity as soil salinization is becoming an increasing concern for agriculture with high soil Na(+) levels leading to reduced yields and economic loss. Much of our knowledge on the molecular mechanisms employed by plants to combat salinity stress has come from work on salt-sensitive plants, but studies on naturally occurring highly salt-resistant plants, halophytes, and direct comparisons between closely related glycophytes and halophytes, could help to further our understanding of salinity

Soil water repellency of the artificial soil and natural soil in rocky slopes as affected by the drought stress and polyacrylamide.

PubMed

Chen, Zhang; Wang, Ruixin; Han, Pengyuan; Sun, Hailong; Sun, Haifeng; Li, Chengjun; Yang, Lixia

2018-04-01

Soil water repellency (SWR) causes reduced soil water storage, enhanced runoff and reduced ecosystem productivity. Therefore, characterization of SWR is a prerequisite for effective environmental management. SWR has been reported under different soils, land uses and regions of the world, particularly in forest land and after wildfires; however, the understanding of this variable in the artificial soil of rocky slope eco-engineering is still rather limited. This study presented the characterization of SWR in the artificial soil affected by the polyacrylamide (PAM) and drought stress. There were two molecular weights of PAM, and the CK was without PAM application. Three types of soil were studied: natural soil and two types of artificial soil which have been sprayed for 1y and 5y, respectively. The drought stress experiments had three drought gradients, lasted for three weeks. Water repellency index (WRI) and soil-water contact angle (β) were determined using intrinsic sorptivity method by measuring the water sorptivity (S W ) and ethanol sorptivity (S E ) in all soil samples. The results showed that (1) Polyacrylamide treatments significantly increased S W by 3% to 38%, and reduced S E by 1% to 15%, WRI by 6% to 38%, β by 3% to 23% compared to the control group. Polyacrylamide treatments also increased water-stable aggregates content and total porosity by 22% to 33%, 11% to 20% relative to the control, while PAM with a higher molecular weight performed best. (2) The interaction between PAM and drought stress had a significant effect on WRI and β for all soil types (P<0.01) while it only had a significant effect on S W and S E for the artificial soil (P<0.01). (3) The artificial soil had a greater WRI and β than the natural soil. Copyright © 2017 Elsevier B.V. All rights reserved.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Factors affecting HCH and DDT in soils around watersheds of Beijing reservoirs, China.

PubMed

Hu, Wenyou; Lu, Yonglong; Wang, Tieyu; Luo, Wei; Zhang, Xiang; Geng, Jing; Wang, Guang; Shi, Yajuan; Jiao, Wentao; Chen, Chunli

2010-04-01

The factors that influence the dynamics of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) in soils around the watersheds of Beijing reservoirs were examined. Compared with other studies on HCH and DDT in soils and established reference values, the concentrations of HCH and DDT in soils around our study area were relatively low. The relationships between HCH and DDT concentrations and land use, soil texture, and soil properties were discussed. HCH and DDT concentrations were higher in arable soils than those in uncultivated fallow soils. Although land use was the most important factor affecting HCH and DDT residues, additional factors such as soil texture and soil total organic carbon were also involved in pesticide retention in soils. The results indicated that the historical agricultural applications of HCH and DDT were the major source of their residues. Atmospheric deposition, as well as long-distance transportation and inputs from surrounding weathered agricultural soils may also serve as important sources of HCH and DDT residues in the watersheds.

Physiological responses to salt stress of salt-adapted and directly salt (NaCl and NaCl+Na2SO4 mixture)-stressed cyanobacterium Anabaena fertilissima.

PubMed

Swapnil, Prashant; Rai, Ashwani K

2018-05-01

Soil salinity in nature is generally mixed type; however, most of the studies on salt toxicity are performed with NaCl and little is known about sulfur type of salinity (Na 2 SO 4 ). Present study discerns the physiologic mechanisms responsible for salt tolerance in salt-adapted Anabaena fertilissima, and responses of directly stressed parent cells to NaCl and NaCl+Na 2 SO 4 mixture. NaCl at 500 mM was lethal to the cyanobacterium, whereas salt-adapted cells grew luxuriantly. Salinity impaired gross photosynthesis, electron transport activities, and respiration in parent cells, but not in the salt-adapted cells, except a marginal increase in PSI activity. Despite higher Na + concentration in the salt mixture, equimolar NaCl appeared more inhibitive to growth. Sucrose and trehalose content and antioxidant activities were maximal in 250 mM NaCl-treated cells, followed by salt mixture and was almost identical in salt-adapted (exposed to 500 mm NaCl) and control cells, except a marginal increase in ascorbate peroxidase activity and an additional fourth superoxide dismutase isoform. Catalase isoform of 63 kDa was induced only in salt-stressed cells. Salinity increased the uptake of intracellular Na + and Ca 2+ and leakage of K + in parent cells, while cation level in salt-adapted cells was comparable to control. Though there was differential increase in intracellular Ca 2+ under different salt treatments, ratio of Ca 2+ /Na + remained the same. It is inferred that stepwise increment in the salt concentration enabled the cyanobacterium to undergo priming effect and acquire robust and efficient defense system involving the least energy.

Distribution of Root-Associated Bacterial Communities Along a Salt-Marsh Primary Succession.

PubMed

Wang, Miao; Yang, Pu; Falcão Salles, Joana

2015-01-01

Proper quantification of the relative influence of soil and plant host on the root-associated microbiome can only be achieved by studying its distribution along an environmental gradient. Here, we used an undisturbed salt marsh chronosequence to study the bacterial communities associated with the soil, rhizosphere and the root endopshere of Limonium vulgare using 454-pyrosequencing. We hypothesize that the selective force exerted by plants rather than soil would regulate the dynamics of the root-associated bacterial assembly along the chronosequence. Our results showed that the soil and rhizosphere bacterial communities were phylogenetically more diverse than those in the endosphere. Moreover, the diversity of the rhizosphere microbiome followed the increased complexity of the abiotic and biotic factors during succession while remaining constant in the other microbiomes. Multivariate analyses showed that the rhizosphere and soil-associated communities clustered by successional stages, whereas the endosphere communities were dispersed. Interestingly, the endosphere microbiome showed higher turnover, while the bulk and rhizosphere soil microbiomes became more similar at the end of the succession. Overall, we showed that soil characteristics exerted an overriding influence on the rhizosphere microbiome, although plant effect led to a clear diversity pattern along the succession. Conversely, the endosphere microbiome was barely affected by any of the environmental measurements and very distinct from other communities.

Discretionary salt use in airline meal service.

PubMed

Wallace, S; Wellman, N S; Dierkes, K E; Johnson, P M

1987-02-01

Salt use in airline meal service was studied through observation of returned meal trays of 932 passengers. Observation and weighing of salt packets on returned trays revealed that 64% of passengers did not salt their airline dinner, while 6% used the entire salt packet, 0.92 gm NaCl (362 mg Na). Average discretionary salt use among the 234 passengers (25%) who added salt was 0.57 gm NaCl (232 mg Na). Estimates of total sodium in the four airline dinners averaged 2.0 gm NaCl (786 mg Na). Laboratory assays of menu items produced by the airline foodservice differed 3% to 19% from estimated values. Sodium content of the four airline dinner menus was similar and did not affect salt use. Discretionary salt use was related to the total amount of entrée consumed but was not affected by the amount of salad consumed. It is postulated that salt use in the "captive" airline situation is predicated on consistent, habitual practices. Lowering sodium consumption in this setting may require alteration in both food preparation methods and quantity of salt presented in the packets.

Biochar pyrolyzed at two temperatures affects Escherichia coli transport through a sandy soil.

PubMed

Bolster, Carl H; Abit, Sergio M

2012-01-01

The incorporation of biochar into soils has been proposed as a means to sequester carbon from the atmosphere. An added environmental benefit is that biochar has also been shown to increase soil retention of nutrients, heavy metals, and pesticides. The goal of this study was to evaluate whether biochar amendments affect the transport of Escherichia coli through a water-saturated soil. We looked at the transport of three E. coli isolates through 10-cm columns packed with a fine sandy soil amended with 2 or 10% (w/w) poultry litter biochar pyrolyzed at 350 or 700°C. For all three isolates, mixing the high-temperature biochar at a rate of 2% into the soil had no impact on transport behavior. When added at a rate of 10%, a reduction of five orders of magnitude in the amount of E. coli transported through the soil was observed for two of the isolates, and a 60% reduction was observed for the third isolate. Mixing the low-temperature biochar into the soil resulted in enhanced transport through the soil for two of the isolates, whereas no significant differences in transport behavior were observed between the low-temperature and high-temperature biochar amendments for one isolate. Our results show that the addition of biochar can affect the retention and transport behavior of E. coli and that biochar application rate, biochar pyrolysis temperature, and bacterial surface characteristics were important factors determining the transport of E. coli through our test soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

To Identify the Important Soil Properties Affecting Dinoseb Adsorption with Statistical Analysis

PubMed Central

Guan, Yiqing; Wei, Jianhui; Zhang, Danrong; Zu, Mingjuan; Zhang, Liru

2013-01-01

Investigating the influences of soil characteristic factors on dinoseb adsorption parameter with different statistical methods would be valuable to explicitly figure out the extent of these influences. The correlation coefficients and the direct, indirect effects of soil characteristic factors on dinoseb adsorption parameter were analyzed through bivariate correlation analysis, and path analysis. With stepwise regression analysis the factors which had little influence on the adsorption parameter were excluded. Results indicate that pH and CEC had moderate relationship and lower direct effect on dinoseb adsorption parameter due to the multicollinearity with other soil factors, and organic carbon and clay contents were found to be the most significant soil factors which affect the dinoseb adsorption process. A regression is thereby set up to explore the relationship between the dinoseb adsorption parameter and the two soil factors: the soil organic carbon and clay contents. A 92% of the variation of dinoseb sorption coefficient could be attributed to the variation of the soil organic carbon and clay contents. PMID:23737715

Understanding the Spatio-Temporal Dynamics of Denitrification in an Oregon Salt Marsh

NASA Astrophysics Data System (ADS)

Moon, J. B.; Stecher, H. A.; DeWitt, T.; Nahlik, A.; Fennessy, M. S.; Michael, L.; Regutti, R.; Mckane, R.; Marois, D.; Naithani, K. J.

2016-12-01

Salt marshes are highly susceptible to a range of climate change effects (e.g., sea-level rise, salinity changes, storm severity, shifts in vegetation across watershed). It is unclear how these effects will alter the spatial and temporal dynamics of denitrification, a potential pathway of nitrogen interception and removal from adjacent estuaries. Our overall objective is to determine whether salt marshes in the Pacific Northwest act as sources or sinks of nitrogen to estuaries, and to be able to predict changes in these dynamics under future climate scenarios. We have built a probabilistic denitrification model based on observations from a salt marsh in the Yaquina Estuary (Newport, Oregon). We observed a non-linear relationship between denitrification rates and distance to the marsh-upland interface and soil nitrate concentrations, which are indicators of nitrate delivery flow paths from upslope red alder. We also modeled spatial variability in oxygen availability as a function of elevation, which affects inundation period, and distance to channel, which affects the saturation period through the dewatering rate. Simulations suggest denitrification "hot spots" occur in mid-marsh locations, where both nitrate availability and inundation periods are maximized. Once marsh accretion is outpaced, sea level rise will likely reduce salt marsh area due to steep adjacent uplands that limit marsh retreat, and increase inundation duration near the marsh-upland interface. Expansion of red alder cover is concurrently expected to increase nitrate availability to downslope ecosystems. Taking these effects together, our future scenario simulations suggest a movement of "hot-spots" towards the marsh-upland boundary.

Effects of rock fragments on water dynamics in a fire-affected soil

NASA Astrophysics Data System (ADS)

Gordillo-Rivero, Ángel J.; García-Moreno, Jorge; Jordán, Antonio; Zavala, Lorena M.

2014-05-01

Rock fragments (RF) are common in the surface of Mediterranean semiarid soils, and have important effects on the soil physical (bulk density and porosity) and hydrological processes (infiltration, evaporation, splash erosion and runoff generation) (Poesen and Lavee, 1994; Rieke-Zapp et al., 2007). In some cases, RFs in Mediterranean areas have been shown to protect bare soils from erosion risk (Cerdà, 2001; Martínez-Zavala, Jordán, 2008; Zavala et al., 2010). Some of these effects are much more relevant when vegetation cover is low or has been reduced after land use change or other causes, as forest fires. Although very few studies exist, the interest on the hydrological effects of RFs in burned areas is increasing recently. After a forest fire, RFs may contribute significantly to soil recovery. In this research we have studied the effect of surface and embedded RFs on soil water control, infiltration and evaporation in calcareous fire-affected soils from a Mediterranean area (SW Spain). For this study, we selected an area with soils derived from limestone under holm oak forest, recently affected by a moderate severity forest fire. The proportion of RF cover showed a significant positive relation with soil water-holding capacity and infiltration rates, although infiltration rate reduced significantly when RF cover increased above a certain threshold. Soil evaporation rate decreased with increasing volumetric content of RFs and became stable with RF contents approximately above 30%. Evaporation also decreased with increasing RF cover. When RF cover increased above 50%, no significant differences were observed between burned and control vegetated plots. REFERENCES Poesen, J., Lavee, H. 1994. Rock fragments in top soils: significance and processes. Catena Supplement 23, 1-28. Cerdà, A. 2001. Effect of rock fragment cover on soil infiltration, interrill runoff and erosion. European Journal of Soil Science 52, 59-68. DOI: 10.1046/j.1365-2389.2001.00354.x. Rieke

Decreased summer drought affects plant productivity and soil carbon dynamics in Mediterranean woodland

NASA Astrophysics Data System (ADS)

Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

2011-06-01

Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. The throughfall manipulation experiment started in 2004 and we report data up to the 2009 growing season. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 50 % and 220 %, respectively, as compared to control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction of precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodland. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long term soil C stocks.

Environmental impact of irrigation in la violada district (Spain): I. Salt export patterns.

PubMed

Isidoro, D; Quílez, D; Aragüés, R

2006-01-01

Salt loading in irrigation return flows contributes to the salinization of the receiving water bodies, particularly when originated in salt-affected areas as frequently found in the middle Ebro River basin (Spain). We determined the salt loading in La Violada Gully from the total dissolved solids (TDS) and flows (Q) during the 1995 to 1998 hydrological years. Since this gully collects flows from various sources, an end-member mixing analysis (EMMA) was performed to quantify the drainage flow from La Violada Irrigation District (VID). Three flow components were identified in La Violada Gully: drainage waters from VID (Qd); tail-waters from irrigation ditches, spill-over, and seepage from the Monegros Canal (Qo); and ground water inflows (Qg) originating in the dryland watershed. Gypsum in the soils of VID was the main source for salts in La Violada Gully (flow-weighted mean TDS=1720 mg L-1, dominated by sulfate and calcium). The contribution of Qg to the total gully flow during the 1996 irrigation season was low (6.5% of the total flow). The 1995 to 1998 annual salt load average in La Violada Gully was 78 628 Mg, 71% of which was exported during the irrigation season. The 1995 to 1998 irrigation season salt load average in Qd was 43 015 Mg (77% of the total load). Thus, irrigated agriculture in VID was the main source of salt loading in this gully, with a yield of 11.1 Mg of salts per hectare of irrigated land for the irrigation season. Efficient irrigation systems and irrigation management practices that reduce Qd are key factors for controlling off-site salt pollution of these gypsum-rich irrigated areas.

Xiphinema americanum as Affected by Soil Organic Matter and Porosity.

PubMed

Ponchillia, P E

1972-07-01

The effects of four soil types, soil porosity, particle size, and organic matter were tested on survival and migration of Xiphinema americanum. Survival and migration were significantly greater in silt loam than in clay loam and silty clay soils. Nematode numbers were significantly greater in softs planted with soybeans than in fallow softs. Nematode survival was greatest at the higher of two pore space levels in four softs. Migration of X. americanum through soft particle size fractions of 75-150, 150-250, 250-500, 500-700, and 700-1,000 mu was significantly greater in the middle three fractions, with the least occurring in the smallest fraction. Additions of muck to silt loam and loamy sand soils resulted in reductions in survival and migration of the nematode. The fulvic acid fraction of muck, extracted with sodium hydroxide, had a deleterious effect on nematode activity. I conclude that soils with small amounts of air-filled pore space, extremes in pore size, or high organic matter content are deleterious to the migration and survival of X. americanum, and that a naturally occurring toxin affecting this species may be present in native soft organic matter.

Compositions, Protease Inhibitor and Gelling Property of Duck Egg Albumen as Affected by Salting

PubMed Central

2018-01-01

Chemical compositions, trypsin inhibitory activity, and gelling properties of albumen from duck egg during salting of 30 days were studied. As the salting time increased, moisture content decreased, the salt content and surface hydrophobicity increased (p<0.05). Trypsin inhibitory activity and specific activity were continuously decreased throughout the salting time of 30 days (p<0.05). This coincided with the decrease in band intensity of inhibitor with molecular weight of 44 kDa as examined by inhibitory activity staining. Nevertheless, no differences in protein patterns were observed in albumen during the salting of 30 days. Based on texture profile analysis, hardness, springiness, gumminess, chewiness, and resilience of albumen gel decreased with increasing salting time. Conversely, salted albumen gels exhibited higher cohesiveness and adhesiveness, compared to those of fresh albumen. Scanning electron microscopic study revealed that gel of salted albumen showed the larger voids and less compactness. In general, salting lowered trypsin inhibitory activity and gelling property of albumen from duck egg to some extent. Nevertheless, the salted albumen with the remaining inhibitor could be an alternative additive for surimi or other meat products to prevent proteolysis. PMID:29725221

The Biotoxicity of Mars Soils

NASA Technical Reports Server (NTRS)

Kerney, Krystal

2010-01-01

Recent evidence from the Opportunity and Spirit rovers suggests that the soils on Mars might be very high in biotoxic materials induding sulfate salts, chlorides, and acidifying agents. Yet, very little is known about how the chemistries of Mars soils might affect the survival and growth of terrestrial microorganisms. The primary objectives of the proposed research will be to: (1) prepare and characterize Mars analog soils amended with potential biotoxic levels of sulfates, chlorides, and acidifying minerals; (2) use the stimulants to conduct a series of toxicology assays to determine if terrestrial microorganisms from spacecraft or extreme environments can survive direct exposure to the biotoxic soils, and (3) mix soils from extreme environments on Earth into Mars analog soils to determine if terrestrial microorganisms can grow and replicate under Martian conditions. The Mars analog soils will be thoroughly characterized by a wide diversity of soil chemistry assays to determine the exact nature of the soluble biotoxic components following hydration. The microbial experiments will be designed to test the effects of Mars stimulants on microbial survival, growth and replication during direct challenge experiments. Toxicology experiments will be designed to mimic terrestrial microbes coming into contact with biotoxic soils with and without liquid water. Results are expected to help" ... characterize the limits of life in ... planetary environments ... " and may help constrain the search for life on Mars.

The effects of snow and salt on ice table stability in University Valley, Antarctica

USGS Publications Warehouse

Williams, Kaj; Heldmann, Jennifer L.; McKay, Christopher P.; Mellon, Michael T.

2018-01-01

The Antarctic Dry Valleys represent a unique environment where it is possible to study dry permafrost overlaying an ice-rich permafrost. In this paper, two opposing mechanisms for ice table stability in University Valley are addressed: i) diffusive recharge via thin seasonal snow deposits and ii) desiccation via salt deposits in the upper soil column. A high-resolution time-marching soil and snow model was constructed and applied to University Valley, driven by meteorological station atmospheric measurements. It was found that periodic thin surficial snow deposits (observed in University Valley) are capable of drastically slowing (if not completely eliminating) the underlying ice table ablation. The effects of NaCl, CaCl2 and perchlorate deposits were then modelled. Unlike the snow cover, however, the presence of salt in the soil surface (but no periodic snow) results in a slight increase in the ice table recession rate, due to the hygroscopic effects of salt sequestering vapour from the ice table below. Near-surface pore ice frequently forms when large amounts of salt are present in the soil due to the suppression of the saturation vapour pressure. Implications for Mars high latitudes are discussed.

Water management can reinforce plant competition in salt-affected semi-arid wetlands

NASA Astrophysics Data System (ADS)

Coletti, Janaine Z.; Vogwill, Ryan; Hipsey, Matthew R.

2017-09-01

The diversity of vegetation in semi-arid, ephemeral wetlands is determined by niche availability and species competition, both of which are influenced by changes in water availability and salinity. Here, we hypothesise that ignoring physiological differences and competition between species when managing wetland hydrologic regimes can lead to a decrease in vegetation diversity, even when the overall wetland carrying capacity is improved. Using an ecohydrological model capable of resolving water-vegetation-salt feedbacks, we investigate why water surface and groundwater management interventions to combat vegetation decline have been more beneficial to Casuarina obesa than to Melaleuca strobophylla, the co-dominant tree species in Lake Toolibin, a salt-affected wetland in Western Australia. The simulations reveal that in trying to reduce the negative effect of salinity, the management interventions have created an environment favouring C. obesa by intensifying the climate-induced trend that the wetland has been experiencing of lower water availability and higher root-zone salinity. By testing alternative scenarios, we show that interventions that improve M. strobophylla biomass are possible by promoting hydrologic conditions that are less specific to the niche requirements of C. obesa. Modelling uncertainties were explored via a Markov Chain Monte Carlo (MCMC) algorithm. Overall, the study demonstrates the importance of including species differentiation and competition in ecohydrological models that form the basis for wetland management.

Soil characteristics of semidesert soils along a precipitation gradient in the Negev (Israel)

NASA Astrophysics Data System (ADS)

Steckenmesser, Daniel; Drahorad, Sylvie; Felix-Henningsen, Peter

2010-05-01

The sand dunes of the north-western Negev desert (Israel) show a unique precipitation gradient on a short distance. This area is build up by the same parent material and suited to investigate the influence of changes in rainfall on soil characteristics in semi-desert ecosystems. The study site is the western extension of the Sinai sand field, the sand dunes are stabilised by biological soil crusts and perennial vegetation like Retama raetam. Along this precipitation gradient the three investigation areas Nizzana South (90mm ^a-), Nizzana 84 (130mm ^a-1) and Nizzana 69 (170mm ^a-1) are situated. At every study site two soil profiles were investigated, each under the legume Retama raetam and in the bare interspace covered by biological soil crusts. The soil samples were taken at the interdune positions at every study site. The soil sampling included the biological soil crust, the topsoil and the subsoil up to 1,5 m. The narrow sampling of 20cm wide steps allow a mapping of the distribution of nutrients, carbonates and soluble salts of in order to show the impact of perennial plants and rainfall on soil properties. Soluble salts and nutrients were measured in a 1:5 water extraction, calcium carbonate was determined according to Scheibler. The data shows a strong influence of perennial shrubs on the deposition of dust and the redistribution of nutrients compared to the bare interspace. The distribution of highly and less soluble salts below the perennial shrub proofs a shallower water infiltration than in the comparable interspace area. The interspace between the plants is covered by a biological soil crust, which also strongly influences the matter fluxes by nutrient-fixation, creation of runoff and stabilization of the soil surface. These biological soil crusts show higher amounts of elements than the subsoils. The comparison of the three areas along the rainfall gradient shows higher inputs of soluble salts with increasing precipitation due to wet deposition, while

How Do Changes to the Railroad Causeway in Utah’s Great Salt Lake Affect Water and Salt Flow?

PubMed Central

White, James S.; Null, Sarah E.; Tarboton, David G.

2015-01-01

Managing terminal lake elevation and salinity are emerging problems worldwide. We contribute to terminal lake management research by quantitatively assessing water and salt flow for Utah’s Great Salt Lake. In 1959, Union Pacific Railroad constructed a rock-filled causeway across the Great Salt Lake, separating the lake into a north and south arm. Flow between the two arms was limited to two 4.6 meter wide rectangular culverts installed during construction, an 88 meter opening (referred to locally as a breach) installed in 1984, and the semi porous material of the causeway. A salinity gradient developed between the two arms of the lake over time because the south arm receives approximately 95% of the incoming streamflow entering Great Salt Lake. The north arm is often at, or near, salinity saturation, averaging 317 g/L since 1966, while the south is considerably less saline, averaging 142 g/L since 1966. Ecological and industrial uses of the lake are dependent on long-term salinity remaining within physiological and economic thresholds, although optimal salinity varies for the ecosystem and between diverse stakeholders. In 2013, Union Pacific Railroad closed causeway culverts amid structural safety concerns and proposed to replace them with a bridge, offering four different bridge designs. As of summer 2015, no bridge design has been decided upon. We investigated the effect that each of the proposed bridge designs would have on north and south arm Great Salt Lake elevation and salinity by updating and applying US Geological Survey’s Great Salt Lake Fortran Model. Overall, we found that salinity is sensitive to bridge size and depth, with larger designs increasing salinity in the south arm and decreasing salinity in the north arm. This research illustrates that flow modifications within terminal lakes cannot be separated from lake salinity, ecology, management, and economic uses. PMID:26641101

Contribution of attendant anions on cadmium toxicity to soil enzymes.

PubMed

Tian, Haixia; Kong, Long; Megharaj, Mallavarapu; He, Wenxiang

2017-11-01

Sorption and desorption are critical processes to control the mobility and biotoxicity of cadmium (Cd) in soils. It is known that attendant anion species of heavy metals could affect metal adsorption on soils and might further alter their biotoxicity. However, for Cd, the influence of attendant anions on its sorption in soils and subsequent toxicity on soil enzymes are still unknown. In this work, four Cd compounds with different salt anions (SO 4 2- , NO 3 - , Cl - , and Ac - ) were selected to investigate their impact of on the sorption, soil dehydrogenase activity (DHA) and alkaline phosphatase activity (ALP). Thus, a series of simulated Cd pollution batch experiments including measuring adsorption-desorption behavior of Cd on soils and soil enzyme activities were carried out. Results showed that CdSO 4 exhibited highest sorption capacity among the tested soils except in Hunan soil. The Cd sorption with NO 3 - displayed a similar behavior with Cl - on all tested soils. Compared with soil properties, all four kinds of anions on Cd sorption played a more significant role affecting Cd ecological toxicity to soil DHA and ALP. Cd in acetate or nitrate form appears more sensitive towards DHA than sulphate and chloride, while the later pair is more toxic towards ALP than the former. These results have important implications for evaluation of Cd contamination using soil enzyme as bioindicator. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deposition, accumulation, and alteration of Cl−, NO3−, ClO4− and ClO3− salts in a hyper-arid polar environment: Mass balance and isotopic constraints

USGS Publications Warehouse

Jackson, Andrew; Davila, Alfonso F.; Böhlke, John Karl; Sturchio, Neil C.; Sevanthi, Ritesh; Estrada, Nubia; Brundrett, Maeghan; Lacelle, Denis; McKay, Christopher P.; Poghosyan, Armen; Pollard, Wayne; Zacny, Kris

2016-01-01

The salt fraction in permafrost soils/sediments of the McMurdo Dry Valleys (MDV) of Antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction. Previous analyses of the salt fraction in MDV permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stratospheric sources. We expand upon this work by evaluating permafrost soil/sediments in University Valley, located in the ultraxerous zone where both liquid water transport and marine influences are minimal. We determined the abundances of Cl−, NO3−, ClO4− and ClO3− in dry and ice-cemented soil/sediments, snow and glacier ice, and also characterized Cl− and NO3−isotopically. The data are not consistent with salt deposition in a sublimation till, nor with nuclear weapon testing fall-out, and instead point to a dominantly stratospheric source and to varying degrees of post depositional transformation depending on the substrate, from minimal alteration in bare soils to significant alteration (photodegradation and/or volatilization) in snow and glacier ice. Ionic abundances in the dry permafrost layer indicate limited vertical transport under the current climate conditions, likely due to percolation of snowmelt. Subtle changes in ClO4−/NO3− ratios and NO3− isotopic composition with depth and location may reflect both transport related fractionation and depositional history. Low molar ratios of ClO3−/ClO4− in surface soils compared to deposition and other arid systems suggest significant post depositional loss of ClO3−, possibly due to reduction by iron minerals, which may have important implications for oxy-chlorine species on Mars. Salt accumulation varies with distance along the valley and apparent accumulation times based on multiple methods range from ∼10 to 30 kyr near the glacier to 70–200 kyr near the valley mouth. The relatively young age

Evaluation of remediation techniques in soils affected by residual contamination with heavy metals and arsenic.

PubMed

García-Carmona, M; Romero-Freire, A; Sierra Aragón, M; Martínez Garzón, F J; Martín Peinado, F J

2017-04-15

Residual soil pollution from the Aznalcóllar mine spill is still a problem in some parts of the affected area, today converted in the Guadiamar Green Corridor. Dispersed spots of polluted soils, identified by the absence of vegetation, are characterized by soil acid pH and high concentrations of As, Pb, Cu and Zn. Ex situ remediation techniques were performed with unrecovered soil samples. Landfarming, Composting and Biopiles techniques were tested in order to immobilize pollutants, to improve soil properties and to promote vegetation recovery. The effectiveness of these techniques was assessed by toxicity bioassays: Lactuca sativa L. root elongation test, Vibrio fischeri bioluminescence reduction test, soil induced respiration test, and Eisenia andrei survival and metal bioaccumulation tests. Landfarming and Composting were not effective techniques, mainly due to the poor improvement of soil properties which maintained high soluble concentrations of Zn and Cu after treatments. Biopile technique, using adjacent recovered soils in the area, was the most effective action in the reduction of soil toxicity; the improvement of soil properties and the reduction in pollutants solubility were key to improve the response of the tested organisms. Therefore, the mixture of recovered soils with polluted soils in the areas affected by residual contamination is considered a more suitable technique to reduce the residual pollution and to promote the complete soil recovery in the Guadiamar Green Corridor. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synchrotron microtomographic quantification of geometrical soil pore characteristics affected by compaction

NASA Astrophysics Data System (ADS)

Udawatta, Ranjith P.; Gantzer, Clark J.; Anderson, Stephen H.; Assouline, Shmuel

2016-05-01

Soil compaction degrades soil structure and affects water, heat, and gas exchange as well as root penetration and crop production. The objective of this study was to use X-ray computed microtomography (CMT) techniques to compare differences in geometrical soil pore parameters as influenced by compaction of two different aggregate size classes. Sieved (diameter < 2 mm and < 0.5 mm) and repacked (1.51 and 1.72 Mg m-3) Hamra soil cores of 5 by 5 mm (average porosities were 0.44 and 0.35) were imaged at 9.6 μm resolution at the Argonne Advanced Photon Source (synchrotron facility) using X-ray CMT. Images of 58.9 mm3 volume were analyzed using 3-Dimensional Medial Axis (3-DMA) software. Geometrical characteristics of the spatial distributions of pore structures (pore radii, volume, connectivity, path length, and tortuosity) were numerically investigated. Results show that the coordination number (CN) distribution and path length (PL) measured from the medial axis were reasonably fit by exponential relationships P(CN) = 10-CN/Co and P(PL) = 10-PL/PLo, respectively, where Co and PLo are the corresponding characteristic constants. Compaction reduced porosity, average pore size, number of pores, and characteristic constants. The average pore radii (63.7 and 61 µm; p < 0.04), largest pore volume (1.58 and 0.58 mm3; p = 0.06), number of pores (55 and 50; p = 0.09), and characteristic coordination number (3.74 and 3.94; p = 0.02) were significantly different between the low-density than the high-density treatment. Aggregate size also influenced measured geometrical pore parameters. This analytical technique provides a tool for assessing changes in soil pores that affect hydraulic properties and thereby provides information to assist in assessment of soil management systems.

Synchrotron Microtomographic Quantification of Geometrical Soil Pore Characteristics Affected by Compaction

NASA Astrophysics Data System (ADS)

Udawatta, Ranjith; Gantzer, Clark; Anderson, Stephen; Assouline, Shmuel

2015-04-01

Soil compaction degrades soil structure and affects water, heat, and gas exchange as well as root penetration and crop production. The objective of this study was to use X-ray computed microtomography (CMT) techniques to compare differences in geometrical soil pore parameters as influenced by compaction of two different aggregate size classes. Sieved (diam. < 2mm and < 0.5mm) and repacked (1.51 and 1.72 Mg m-3) Hamra soil cores of 5- by 5-mm (average porosities were 0.44 and 0.35) were imaged at 9.6-micrometer resolution at the Argonne Advanced Photon Source (synchrotron facility) using X-ray computed microtomography. Images of 58.9 mm3 volume were analyzed using 3-Dimensional Medial Axis (3DMA) software. Geometrical characteristics of the spatial distributions of pore structures (pore radii, volume, connectivity, path length, and tortuosity) were numerically investigated. Results show that the coordination number (CN) distribution and path length (PL) measured from the medial axis were reasonably fit by exponential relationships P(CN)=10-CN/Co and P(PL)=10-PL/PLo, respectively, where Co and PLo are the corresponding characteristic constants. Compaction reduced porosity, average pore size, number of pores, and characteristic constants. The average pore radii (64 and 61 μm; p<0.04), largest pore volume (1.6 and 0.6 mm3; p=0.06), number of pores (55 and 50; p=0.09), characteristic coordination number (6.3 and 6.0; p=0.09), and characteristic path length number (116 and 105; p=0.001) were significantly greater in the low density than the high density treatment. Aggregate size also influenced measured geometrical pore parameters. This analytical technique provides a tool for assessing changes in soil pores that affect hydraulic properties and thereby provides information to assist in assessment of soil management systems.

Synchrotron microtomographic quantification of geometrical soil pore characteristics affected by compaction

NASA Astrophysics Data System (ADS)

Udawatta, R. P.; Gantzer, C. J.; Anderson, S. H.; Assouline, S.

2015-07-01

Soil compaction degrades soil structure and affects water, heat, and gas exchange as well as root penetration and crop production. The objective of this study was to use X-ray computed microtomography (CMT) techniques to compare differences in geometrical soil pore parameters as influenced by compaction of two different aggregate size classes. Sieved (diam. < 2 mm and < 0.5 mm) and repacked (1.51 and 1.72 Mg m-3) Hamra soil cores of 5- by 5 mm (average porosities were 0.44 and 0.35) were imaged at 9.6-micrometer resolution at the Argonne Advanced Photon Source (synchrotron facility) using X-ray computed microtomography. Images of 58.9 mm3 volume were analyzed using 3-Dimensional Medial Axis (3DMA) software. Geometrical characteristics of the spatial distributions of pore structures (pore radii, volume, connectivity, path length, and tortuosity) were numerically investigated. Results show that the coordination number (CN) distribution and path length (PL) measured from the medial axis were reasonably fit by exponential relationships P(CN) = 10-CN/Co and P(PL) = 10-PL/PLo, respectively, where Co and PLo are the corresponding characteristic constants. Compaction reduced porosity, average pore size, number of pores, and characteristic constants. The average pore radii (63.7 and 61 μm; p < 0.04), largest pore volume (1.58 and 0.58 mm3; p = 0.06), number of pores (55 and 50; p = 0.09), characteristic coordination number (6.32 and 5.94; p = 0.09), and characteristic path length number (116 and 105; p = 0.001) were significantly greater in the low density than the high density treatment. Aggregate size also influenced measured geometrical pore parameters. This analytical technique provides a tool for assessing changes in soil pores that affect hydraulic properties and thereby provides information to assist in assessment of soil management systems.

Biophysical and biochemical constraints imposed by salt stress: learning from halophytes

PubMed Central

Duarte, Bernardo; Sleimi, Noomene; Caçador, Isabel

2014-01-01

Soil salinization is one of the most important factors impacting plant productivity. About 3.6 billion of the world’s 5.2 billion ha of agricultural dry land, have already suffered erosion, degradation, and salinization. Halophytes are typically considered as plants able to complete their life cycle in environments where the salt concentration is above 200 mM NaCl. Salinity adjustment is a complex phenomenon but essential mechanism to overcome salt stress, with both biophysical and biochemical implications. At this level, halophytes evolved in several directions, adopting different strategies. Otherwise, the lack of adaptation to a salt environment would negatively affect their electron transduction pathways and the entire energetic metabolism, the foundation of every plant photosynthesis and biomass production. The maintenance of ionic homeostasis is in the basis of all cellular counteractive measures, in particular in terms of redox potential and energy transduction. In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation with biochemical counteractive mechanisms, integrating data from photosynthetic light harvesting complexes, electron transport chains to the quinone pools, carbon fixation, and energy dissipation metabolism. PMID:25566311

Soil pH, soil type and replant disease affect growth and nutrient absorption in apple rootstocks

USDA-ARS?s Scientific Manuscript database

Rootstocks are the foundation of a healthy and productive orchard. They are the interface between the scion and the soil, providing anchorage, water, nutrients, and disease protection that ultimately affect the productivity and sustainability of the orchard. Recent advances in the science of genet...

Antioxidant enzyme activities are affected by salt content and temperature and influence muscle lipid oxidation during dry-salted bacon processing.

PubMed

Jin, Guofeng; He, Lichao; Yu, Xiang; Zhang, Jianhao; Ma, Meihu

2013-12-01

Fresh pork bacon belly was used as material and manufactured into dry-salted bacon through salting and drying-ripening. During processing both oxidative stability and antioxidant enzyme stability were evaluated by assessing peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and activities of catalase, glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), and their correlations were also analysed. The results showed that all antioxidant enzyme activities decreased (p<0.05) until the end of process; GSH-Px was the most unstable one followed by catalase. Antioxidant enzyme activities were negatively correlated with TBARS (p<0.05), but the correlations were decreased with increasing process temperature. Salt showed inhibitory effect on all antioxidant enzyme activities and was concentration dependent. These results indicated that when process temperature and salt content were low at the same time during dry-salted bacon processing, antioxidant enzymes could effectively control lipid oxidation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ionomic and metabolic responses to neutral salt or alkaline salt stresses in maize (Zea mays L.) seedlings.

PubMed

Guo, Rui; Shi, LianXuan; Yan, Changrong; Zhong, Xiuli; Gu, FengXue; Liu, Qi; Xia, Xu; Li, Haoru

2017-02-10

Soil salinity and alkalinity present a serious threat to global agriculture. However, most of the studies have focused on neutral salt stress, and the information on the metabolic responses of plants to alkaline salt stress is limited. This investigation aimed at determining the influence of neutral salt and alkaline salt stresses on the content of metal elements and metabolites in maize plant tissues, by using mixtures of various proportions of NaCl, NaHCO 3 , Na 2 SO 4 , and Na 2 CO 3 . We found that alkaline salt stress suppressed more pronouncedly the photosynthesis and growth of maize plants than salinity stress. Under alkaline salt stress conditions, metal ions formed massive precipitates, which ultimately reduced plant nutrient availability. On the other hand, high neutral salt stress induced metabolic changes in the direction of gluconeogenesis leading to the enhanced formation of sugars as a reaction contributing to the mitigation of osmotic stress. Thus, the active synthesis of sugars in shoots was essential to the development of salt tolerance. However, the alkaline salt stress conditions characterized by elevated pH values suppressed substantially the levels of photosynthesis, N metabolism, glycolysis, and the production of sugars and amino acids. These results indicate the presence of different defensive mechanisms responsible for the plant responses to neutral salt and alkaline salt stresses. In addition, the increased concentration of organic acids and enhanced metabolic energy might be potential major factors that can contribute to the maintenance intracellular ion balance in maize plants and counteract the negative effects of high pH under alkaline salt stress.

Survival and reversion of a stable L form in soil

NASA Technical Reports Server (NTRS)

Horwitz, A. H.; Casida, L. E., Jr.

1978-01-01

The stable L form of Agromyces ramosus reverted to a bacterial form when incubated in sterilized soil. The cellular and colonial morphology of this bacterial form resembled that of the original parent bacterial form. The two forms differed, however, in that the revertant maintained its bacterial form when transferred onto a low-salt (NaCl) medium but was virtually completely induced into the L-form state on a high-salt medium. The original parent bacterial form was not sensitive to salt. The possibility is discussed that an L-form - bacterial-form cycle for this bacterium might occur naturally in soil. This cycle would be mediated by fluctuations in local salt concentrations in the soil.

Effects of a Storm-Surge Related Salinity Decrease on Greenhouse Gas Emissions in Tidal Salt Marsh Mesocosms

NASA Astrophysics Data System (ADS)

Capooci, M.; Barba, J.; Seyfferth, A.; Vargas, R.

2017-12-01

Salt marshes, along with mangrove forests and seagrass beds, are capable of sequestering large quantities of carbon. Additionally, salt marshes are resilient ecosystems, capable of quickly recovering from disturbances. However, very little is known about how carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ammonia (NH3) fluxes from wetland soils, in addition to pore water chemistry, change with a disturbance event such as a storm surge. Using soil mesocosms from St. Jones Reserve, a National Estuarine Research Reserve, and site-specific water salinity data, we conducted a laboratory experiment that recreated the changes in salinity associated with a storm event and compared them to soils flooded with the mean annual salinity of the St. Jones River. Control and treatment were done in triplicate. We controlled for variations in temperature (set at 21°C) and all cores maintained similar flooded conditions. Treatment included a decrease in salinity based on historic values during storm events (i.e. Hurricane Joaquin). Greenhouse gas (GHG; CO2, CH4, N2O, NH3) emissions were measured hourly using automated chambers. Pore water was collected every day to every other day and analyzed for a variety of parameters, including Fe2+, S2-, SO42-, and NO3-. Auxiliary measurements, such as soil temperature, moisture, and oxygen levels, in addition to pore water salinity, were also taken to ensure that proper conditions were maintained. We found significant increases in CO2, CH4, and N2O emissions when comparing the treatment (lowered salinity) to the control. We found also differences in pore water chemistry between treatment phases, particularly in Fe2+. The results of this experiment have implications for GHG dynamics in salt marsh ecosystems, showcasing the need to measure GHG emissions during and after storm events. This study provides insights into how changes in salinity affect GHG emissions in salt marshes, as well as how ecosystem dynamics respond to a

Results of mineral, chemical, and sulfate isotopic analyses of water, soil, rocks, and soil extracts from the Pariette Draw Watershed, Uinta Basin, Utah

USGS Publications Warehouse

Morrison, Jean M.; Tuttle, Michele L.W.; Fahy, Juli W.

2015-08-06

The goal of this study was to establish a process-based understanding of salt, Se, and B behavior to address whether these contaminants can be better managed, or if uncontrollable natural processes will overwhelm any attempts to bring Pariette Draw into compliance with respect to recently established total maximum daily limits (TMDLs). We collected data to refine our knowledge about the role of rock weathering and soil formation in the transport and storage of salt in the watershed and to show how salt is cycled under irrigated and natural conditions. Our approach was to sample rock, soils, and sediment on irrigated and natural terrain for mineralogical analysis to determine the residence of salt and associated Se and B, classify minerals as primary (related to rock formation) or secondary weathering products, and characterize mineral dissolution kinetics. Mineral and chemical analyses and selective extractions of rocks and soils provide useful information in understanding solute movement and mineral dissolution/ formation. The resulting data are critical in determining residence of salt, Se, and B in weathered rock and soil and understanding the mobility during water-rock-soil interactions. This report summarizes our methods for sample and data collection and tabulates the mineral, chemical, and isotopic data collected.

Remediation of 1,2,3-trichlorobenzene contaminated soil using a combined thermal desorption-molten salt oxidation reactor system.

PubMed

Li, Jin-hui; Sun, Xiao-fei; Yao, Zhi-tong; Zhao, Xiang-yang

2014-02-01

A combined thermal desorption (TD)-molten salt oxidation (MSO) reactor system was applied to remediate the 1,2,3-trichlorobenzene (1,2,3-TCB) contaminated soil. The TD reactor was used to enrich the contaminant from soil, and its dechlorination of the contaminant was achieved in the MSO reactor. The optimum operating conditions of TD, and the effects of MSO reactor temperatures, additive amounts of the TCB on destruction and removal efficiency (DRE) of TCB and chlorine retention efficiency (CRE) were investigated. The reaction mechanism and pathway were proposed as well. The combined system could remediate the contaminated soil at a large scale of concentration from 5 to 25gkg(-1), and the DRE and CRE reached more than 99% and 95%, respectively, at temperatures above 850°C. The reaction emissions included C6H6, CH4, CO and CO2, and chlorinated species were not detected. It was found that a little increase in the temperature can considerably reduce the emission of C6H6, CH4, and CO, while the CO2 level increased. Copyright © 2014. Published by Elsevier Ltd.

Dairy manure applications and soil health implications

USDA-ARS?s Scientific Manuscript database

Dairy manure applications can potentially improve soil health by adding organic matter (OM) to the soil. However, intensive dairy manure applications can cause salt accumulations on arid, irrigated soils, impairing soil health, which can reduce crop growth and yield. Soil organic matter, a major c...

Increasing Base Cations in Streams: Another Legacy of Deicing Salts?

NASA Astrophysics Data System (ADS)

Helton, A. M.; Barclay, J. R.; Bellucci, C.; Rittenhouse, C.

2017-12-01

Elevated use of deicing salts directly increases sodium chloride inputs to watersheds. Sodium can accumulate in soils over time and has the potential to leach other cations (e.g., calcium, magnesium, and potassium) from the soil through cation exchange. We hypothesize that increased use of deicing salts results in a legacy of soils depleted in non-sodium base cations with loss of cations to receiving waters. The goal of this project is to quantify temporal trends in base cations and chloride in streams and rivers across the United States. We used Weighted Regressions on Time, Discharge, and Season (WRTDS) to analyze trends in base cations. Our preliminary analysis of 10 rivers in Connecticut with chemical periods of record ranging from 24 - 64 years (median = 55 years), shows that the flux of base cations is increasing in all sites (25 - 366 103 meq ha-1 yr-1 yr-1), driven largely by increases in sodium (23 - 222 103 meq ha-1 yr-1 yr-1), the dominant cation in 7 of the sites. Chloride is also increasing at all sites (26 - 261 103 meq ha-1 yr-1 yr-1), which, in combination with salt use trends, suggests a road salt source for the increased sodium. Non-sodium cations are also increasing in 9 of the sites (8 - 54 103 meq ha-1 yr-1 yr-1), though they are not directly added with most deicing salts. We will compare these trends to other long-term sites across the United States, and quantify relationships between cation trends and land cover, road density, and snowfall.

Where Does Road Salt Go - a Static Salt Model

NASA Astrophysics Data System (ADS)

Yu, C. W.; Liu, F.; Moriarty, V. W.

2017-12-01

Each winter, more than 15 million tons of road salt is applied in the United States for the de-icing purpose. Considerable amount of chloride in road salt flows into streams/drainage systems with the snow melt runoff and spring storms, and eventually goes into ecologically sensitive low-lying areas in the watershed, such as ponds and lakes. In many watersheds in the northern part of US, the chloride level in the water body has increased significantly in the past decades, and continues an upward trend. The environmental and ecological impact of the elevated chloride level can no longer be ignored. However although there are many studies on the biological impact of elevated chloride levels, there are few investigations on how the spatially distributed road salt application affects various parts of the watershed. In this presentation, we propose a static road salt model as a first-order metric to address spacial distribution of salt loading. Derived from the Topological Wetness Index (TWI) in many hydrological models, this static salt model provides a spatial impact as- sessment of road salt applications. To demonstrate the effectiveness of the static model, National Elevation Dataset (NED) of ten-meter resolution of Lake George watershed in New York State is used to generate the TWI, which is used to compute a spatially dis- tributed "salt-loading coefficient" of the whole watershed. Spatially varying salt applica- tion rate is then aggregated, using the salt-loading coefficients as weights, to provide salt loading assessments of streams in the watershed. Time-aggregated data from five CTD (conductivity-temperature-depth) sensors in selected streams are used for calibration. The model outputs and the sensor data demonstrate a strong linear correlation, with the R value of 0.97. The investigation shows that the static modeling approach may provide an effective method for the understanding the input and transport of road salt to within watersheds.

Near-surface gas mapping studies of salt geologic features at Weeks Island and other sites

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

Molecke, M.A.; Carney, K.R.; Autin, W.J.

1996-10-01

Field sampling and rapid gas analysis techniques were used to survey near-surface soil gases for geotechnical diagnostic purposes at the Weeks Island Strategic Petroleum Reserve (SPR) site and other salt dome locations in southern Louisiana. This report presents the complete data, results and interpretations obtained during 1995. Weeks Island 1994 gas survey results are also briefly summarized; this earlier study did not find a definitive correlation between sinkhole No. 1 and soil gases. During 1995, several hundred soil gas samples were obtained and analyzed in the field by gas chromatography, for profiling low concentrations and gas anomalies at ppm tomore » percent levels. The target gases included hydrogen, methane, ethane and ethylene. To supplement the field data, additional gas samples were collected at various site locations for laboratory analysis of target gases at ppb levels. Gases in the near-surface soil originate predominantly from the oil, from petrogenic sources within the salt, or from surface microbial activity. Surveys were conducted across two Weeks Island sinkholes, several mapped anomalous zones in the salt, and over the SPR repository site and its perimeter. Samples were also taken at other south Louisiana salt dome locations for comparative purposes. Notable results from these studies are that elevated levels of hydrogen and methane (1) were positively associated with anomalous gassy or shear zones in the salt dome(s) and (2) are also associated with suspected salt fracture (dilatant) zones over the edges of the SPR repository. Significantly elevated areas of hydrogen, methane, plus some ethane, were found over anomalous shear zones in the salt, particularly in a location over high pressure gas pockets in the salt, identified in the mine prior to SPR operations. Limited stable isotope ratio analyses, SIRA, were also conducted and determined that methane samples were of petrogenic origin, not biogenic.« less

Decreased summer drought affects plant productivity and soil carbon dynamics in a Mediterranean woodland

NASA Astrophysics Data System (ADS)

Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

2011-09-01

Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 58 % and 220 %, respectively, as compared to the control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction in precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.

Evaluation of the Impacts of Marine Salts and Asian Dust on the Forested Yakushima Island Ecosystem, a World Natural Heritage Site in Japan.

PubMed

Nakano, Takanori; Yokoo, Yoriko; Okumura, Masao; Jean, Seo-Ryong; Satake, Kenichi

2012-11-01

To elucidate the influence of airborne materials on the ecosystem of Japan's Yakushima Island, we determined the elemental compositions and Sr and Nd isotope ratios in streamwater, soils, vegetation, and rocks. Streamwater had high Na and Cl contents, low Ca and HCO(3) contents, and Na/Cl and Mg/Cl ratios close to those of seawater, but it had low pH (5.4 to 7.1), a higher Ca/Cl ratio than seawater, and distinct (87)Sr/(86)Sr ratios that depended on the bedrock type. The proportions of rain-derived cations in streamwater, estimated by assuming that Cl was derived from sea salt aerosols, averaged 81 % for Na, 83 % for Mg, 36 % for K, 32 % for Ca, and 33 % for Sr. The Sr value was comparable to the 28 % estimated by comparing Sr isotope ratios between rain and granite bedrock. The soils are depleted in Ca, Na, P, and Sr compared with the parent materials. At Yotsuse in the northwestern side, plants and the soil pool have (87)Sr/(86)Sr ratios similar to that of rainwater with a high sea salt component. In contrast, the Sr and Nd isotope ratios of soil minerals in the A and B horizons approach those of silicate minerals in northern China's loess soils. The soil Ca and P depletion results largely from chemical weathering of plagioclase and of small amounts of apatite and calcite in granitic rocks. This suggests that Yakushima's ecosystem is affected by large amounts of acidic precipitation with a high sea salt component, which leaches Ca and its proxy (Sr) from bedrock into streams, and by Asian dust-derived apatite, which is an important source of P in base cation-depleted soils.

Soil salinisation and irrigation management of date palms in a Saharan environment.

PubMed

Haj-Amor, Zied; Ibrahimi, Mohamed-Khaled; Feki, Nissma; Lhomme, Jean-Paul; Bouri, Salem

2016-08-01

The continuance of agricultural production in regions of the world with chronic water shortages depends upon understanding how soil salinity is impacted by irrigation practises such as water salinity, irrigation frequency and amount of irrigation. A two-year field study was conducted in a Saharan oasis of Tunisia (Lazala Oasis) to determine how the soil electrical conductivity was affected by irrigation of date palms with high saline water. The study area lacked a saline shallow water table. Field results indicate that, under current irrigation practises, soil electrical conductivity can build up to levels which exceed the salt tolerance of date palm trees. The effects of irrigation practises on the soil electrical conductivity were also evaluated using model simulations (HYDRUS-1D) of various irrigation regimes with different frequencies, different amounts of added water and different water salinities. The comparison between the simulated and observed results demonstrated that the model gave an acceptable estimation of water and salt dynamics in the soil profile, as indicated by the small values of root mean square error (RMSE) and the high values of the Nash-Sutcliffe model efficiency coefficient (NSE). The simulations demonstrated that, under field conditions without saline shallow groundwater, saline irrigation water can be used to maintain soil electrical conductivity and soil water content at safe levels (soil electrical conductivity <4 dS m(-1) and soil water content >0.04 cm(3) cm(-3)) if frequent irrigations with small amounts of water (90 % of the evapotranspiration requirements) were applied throughout the year.

Soil and surface layer type affect non-rainfall water inputs

NASA Astrophysics Data System (ADS)

Agam, Nurit; Berliner, Pedro; Jiang, Anxia

2017-04-01

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

Factors affecting cadmium absorbed by pistachio kernel in calcareous soils, southeast of Iran.

PubMed

Shirani, H; Hosseinifard, S J; Hashemipour, H

2018-03-01

Cadmium (Cd) which does not have a biological role is one of the most toxic heavy metals for organisms. This metal enters environment through industrial processes and fertilizers. The main objective of this study was to determine the relationships between absorbed Cd by pistachio kernel and some of soil physical and chemical characteristics using modeling by stepwise regression and Artificial Neural Network (ANN), in calcareous soils in Rafsanjan region, southeast of Iran. For these purposes, 220 pistachio orchards were selected, and soil samples were taken from two depths of 0-40 and 40-80cm. Besides, fruit and leaf samples from branches with and without fruit were taken in each sampling point. The results showed that affecting factors on absorbed Cd by pistachio kernel which were obtained by regression method (pH and clay percent) were not interpretable, and considering unsuitable vales of determinant coefficient (R 2 ) and Root Mean Squares Error (RMSE), the model did not have sufficient validity. However, ANN modeling was highly accurate and reliable. Based on its results, soil available P and Zn and soil salinity were the most important factors affecting the concentration of Cd in pistachio kernel in pistachio growing areas of Rafsanjan. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of deliquescent salts in soils of polar Mars on the flow of the Northern Ice Cap

NASA Astrophysics Data System (ADS)

Fisher, D. A.; Hecht, M. H.; Kounaves, S.; Catling, D.

2008-12-01

The discovery of substantial amounts of magnesium and perchlorate by Phoenix' "Wet Chemistry Lab" (WCL) in the soil of Polar Mars suggests that magnesium perchlorate could be the dominant salt in the polar region's soils. This prospect opens some unexpected doors for moving liquid water around at temperatures as low as -68C. In its fully hydrated form ,this salt water mixture has a high density (~ 1700 kgm /cubic meter) (Besley and Bottomley,1969) and a freezing point of -68C (Pestova et al., 2005).This perchlorate is very deliquescent and gives off heat as it melts ice. About 1.8 gram of ice can be 'melted' by 1 gm of pure magnesium perchlorate . If the reported 1 percent perchlorate is typical of polar soils and if 5 percent of the Northern Permanent Ice Cap is soil then the perchorate , makes up about 0.0005 the of the ice cap. Given the average thickness of the ice cap is about 2000 meters,this suggests there enough perchorate in the ice cap to generate about 2m of salty water at the bed. Because of its density the perclorate salty water would pool over impervious layers and make the bed into a perchorate sludge that could be mobilized and deformed by the overburden of ice. The deformation of mobile beds is a well known phenomenon on some terrestrial glaciers presently and was thought to have played a major role during the Wisconsinan ice age (Fisher et al., 1985) . The perchorate sludge would be deformed and moved outwards possibly resulting its re-introduction to the polar environment. Having a deliquescent salt sludge at the bed whose melting point is -68C would mean that the ice cap could slide on its deformable bed while the ice itself was still very cold and stiff . This possibility has been modeled with a 2D time varying model . Adding the deformable bed material allows ice cap motion even at ice temperatures cold enough to generate and preserve the scarp/trough features. When the perchlorate formation mechanisms and rates are known the ultimate

An assessment of the effectiveness and impact of electrokinetic remediation for pyrene-contaminated soil.

PubMed

Xu, Sujuan; Guo, Shuhai; Wu, Bo; Li, Fengmei; Li, Tingting

2014-11-01

The effectiveness of electrokinetic remediation for pyrene-contaminated soil was investigated by an anode-cathode separated system using a salt bridge. The applied constant voltage was 24 V and the electrode gap was 24 cm. Two types of soil (sandy soil and loam soil) were selected because of their different conductive capabilities. The initial concentrations of pyrene in these soil samples were 261.3mg/kg sandy soil and 259.8 mg/kg loam soil. After treatment of the sandy soil and loam soil for seven days, 56.8% and 20.1% of the pyrene had been removed respectively. Under the same power supply voltage, the removal of the pollutant from the sandy soil was greater than that from the loam soil, due to the higher current and lower pH. Further analysis revealed that the effectiveness of electrokinetic remediation was affected by the energy expenditure, and was associated with changes in soil properties. Copyright © 2014. Published by Elsevier B.V.

Plant growth promoting bacteria as an alternative strategy for salt tolerance in plants: A review.

PubMed

Numan, Muhammad; Bashir, Samina; Khan, Yasmin; Mumtaz, Roqayya; Shinwari, Zabta Khan; Khan, Abdul Latif; Khan, Ajmal; Al-Harrasi, Ahmed

2018-04-01

Approximately 5.2 billion hectare agriculture land are affected by erosion, salinity and soil degradation. Salinity stress has significantly affecting the fertile lands, and therefore possesses a huge impact on the agriculture and economy of a country. Salt stress has severe effects on the growth and development of plants as well as reducing its yield. Plants are inherently equipped with stress tolerance ability to responds the specific type of stress. Plants retained specific mechanisms for salt stress mitigation, such as hormonal stimulation, ion exchange, antioxidant enzymes and activation of signaling cascades on their metabolic and genetic frontiers that sooth the stressed condition. Additional to the plant inherent mechanisms, certain plant growth promoting bacteria (PGPB) also have specialized mechanism that play key role for salt stress tolerance and plant growth promotion. These bacteria triggers plants to produce different plant growth hormones like auxin, cytokinine and gibberellin as well as volatile organic compounds. These bacteria also produces growth regulators like siderophore, which fix nitrogen, solubilize organic and inorganic phosphate. Considering the importance of PGPB in compensation of salt tolerance in plants, the present study has reviewed the different aspect and mechanism of bacteria that play key role in promoting plants growth and yield. It can be concluded that PGPB can be used as a cost effective and economical tool for salinity tolerance and growth promotion in plants. Copyright © 2018 Elsevier GmbH. All rights reserved.

Organic matter and salinity modify cadmium soil (phyto)availability.

PubMed

Filipović, Lana; Romić, Marija; Romić, Davor; Filipović, Vilim; Ondrašek, Gabrijel

2018-01-01

Although Cd availability depends on its total concentration in soil, it is ultimately defined by the processes which control its mobility, transformations and soil solution speciation. Cd mobility between different soil fractions can be significantly affected by certain pedovariables such as soil organic matter (SOM; over formation of metal-organic complexes) and/or soil salinity (over formation of metal-inorganic complexes). Phytoavailable Cd fraction may be described as the proportion of the available Cd in soil which is actually accessible by roots and available for plant uptake. Therefore, in a greenhouse pot experiment Cd availability was observed in the rhizosphere of faba bean exposed to different levels of SOM, NaCl salinity (50 and 100mM) and Cd contamination (5 and 10mgkg -1 ). Cd availability in soil does not linearly follow its total concentration. Still, increasing soil Cd concentration may lead to increased Cd phytoavailability if the proportion of Cd 2+ pool in soil solution is enhanced. Reduced Cd (phyto)availability by raised SOM was found, along with increased proportion of Cd-DOC complexes in soil solution. Data suggest decreased Cd soil (phyto)availability with the application of salts. NaCl salinity affected Cd speciation in soil solution by promoting the formation of CdCl n 2-n complexes. Results possibly suggest that increased Cd mobility in soil does not result in its increased availability if soil adsorption capacity for Cd has not been exceeded. Accordingly, chloro-complex possibly operated just as a Cd carrier between different soil fractions and resulted only in transfer between solid phases and not in increased (phyto)availability. Copyright © 2017 Elsevier Inc. All rights reserved.

Phytoextraction and phytoexcretion of Cd by the leaves of Tamarix smyrnensis growing on contaminated non-saline and saline soils

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

Manousaki, Eleni; Kadukova, Jana; Papadantonakis, Nikolaos

2008-03-15

Phytoremediation and more specifically phytoextraction, is an alternative restoration strategy for the clean up of heavy metal contaminated soils. Phytoextraction can only be successful if suitable plant species colonize the contaminated area, extract the toxic substances and accumulate them in their above ground tissues. In this study, the salt cedar Tamarix smyrnensis that is a widespread salt-tolerant plant in the Mediterranean region has been investigated. A pot experiment is conducted with T. smyrnensis grown in polluted soil with 16 ppm of cadmium and at three different salt concentrations (0.0, 0.5, 3.0% NaCl) for a 10-week period. It took place inmore » an open-air area with natural light, at ambient temperature and humidity in an effort to keep the plants under conditions as similar as possible to those in the field. However, care was taken not to let them be rained on. Temperature ranged from 19 to 50 deg. C with 33 and 21 deg. C being the average day and night temperature, respectively. Humidity ranged from 28% to 87% with a 13-14 h photoperiod. The specific aims of this work are to investigate the accumulation of cadmium via root uptake at different saline conditions and cadmium excretion through salt glands on the surface of the leaves as a probable detoxification mechanism of the plant. Furthermore, measurements of chlorophyll content, biomass, and shoot length are used to evaluate the potential of the plant for the removal of cadmium from contaminated saline and non-saline soils. The experimental data suggest that increased soil salinity results in an increase of the cadmium uptake by T. smyrnensis. Analysis of white salt crystals taken from glandular tissue confirmed the fact that this plant excretes cadmium through its salt glands on the surface of the leaves as a possible detoxification mechanism in order to resist metal toxicity. Excreted cadmium is again released into the environment and it is redeposited on the top soil. Furthermore

Proteomic analysis of salt stress and recovery in leaves of Vigna unguiculata cultivars differing in salt tolerance.

PubMed

de Abreu, Carlos Eduardo Braga; Araújo, Gyedre dos Santos; Monteiro-Moreira, Ana Cristina de Oliveira; Costa, José Hélio; Leite, Hugo de Brito; Moreno, Frederico Bruno Mendes Batista; Prisco, José Tarquinio; Gomes-Filho, Enéas

2014-08-01

Cowpea cultivars differing in salt tolerance reveal differences in protein profiles and adopt different strategies to overcome salt stress. Salt-tolerant cultivar shows induction of proteins related to photosynthesis and energy metabolism. Salinity is a major abiotic stress affecting plant cultivation and productivity. The objective of this study was to examine differential proteomic responses to salt stress in leaves of the cowpea cultivars Pitiúba (salt tolerant) and TVu 2331 (salt sensitive). Plants of both cultivars were subjected to salt stress (75 mM NaCl) followed by a recovery period of 5 days. Proteins extracted from leaves of both cultivars were analyzed by two-dimensional electrophoresis (2-DE) under salt stress and after recovery. In total, 22 proteins differentially regulated by both salt and recovery were identified by LC-ESI-MS/MS. Our current proteome data revealed that cowpea cultivars adopted different strategies to overcome salt stress. For the salt-tolerant cultivar (Pitiúba), increase in abundance of proteins involved in photosynthesis and energy metabolism, such as rubisco activase, ribulose-5-phosphate kinase (Ru5PK) (EC 2.7.1.19), glycine decarboxylase (EC 1.4.4.2) and oxygen-evolving enhancer (OEE) protein 2, was observed. However, these vital metabolic processes were more profoundly affected in salt-sensitive cultivar (TVu), as indicated by the down-regulation of OEE protein 1, Mn-stabilizing protein-II, carbonic anhydrase (EC 4.2.1.1) and Rubisco (EC 4.1.1.39), leading to energy reduction and a decline in plant growth. Other proteins differentially regulated in both cultivars corresponded to different physiological responses. Overall, our results provide information that could lead to a better understanding of the molecular basis of salt tolerance and sensitivity in cowpea plants.

A CIPK protein kinase targets sucrose transporter MdSUT2.2 at Ser254 for phosphorylation to enhance salt tolerance.

PubMed

Ma, Qi-Jun; Sun, Mei-Hong; Kang, Hui; Lu, Jing; You, Chun-Xiang; Hao, Yu-Jin

2018-05-23

Soil salinity is one of the major abiotic stressors that negatively affect crop growth and yield. Salt stress can regulate antioxidants and the accumulation of osmoprotectants. In the study, a sucrose transporter MdSUT2.2 was identified in apple. Overexpression of MdSUT2.2 gene increased salt tolerance in the transgenic apple, compared with the WT control 'Gala'. In addition, it was found that protein MdSUT2.2 was phosphorylated at Ser 254 site in response to salt. A DUAL membrane yeast hybridization system through an apple cDNA library demonstrated that a protein kinase MdCIPK13 interacted with MdSUT2.2. A series of transgenic analysis in apple calli showed that MdCIPK13 was required for the salt-induced phosphorylation of MdSUT2.2 protein and enhanced its stability and transport activity. Finally, it was found that MdCIPK13 improved salt resistance in an MdSUT2.2-dependent manner. These findings had enriched our understanding of the molecular mechanisms underlying abiotic stress. This article is protected by copyright. All rights reserved.

Salt gland distribution in limonium bicolor at the individual level

NASA Astrophysics Data System (ADS)

Leng, B. Y.; Yuan, F.; Dong, X. X.; Wang, B. S.

2018-02-01

Limonium bicolor is a typical exo-recretohalophyte with multi-cellular salt glands. A differential interference contrast (DIC) microscope were applied to investigate the pattern of salt gland distribution in L. bicolor at the individual level. For a single mature leaf, more salt glands are distributed in the leaf central and apical regions than leaf base. For the leaves in different developmental stages, firstly, the density of salt glands linearly decreased at the beginning of leaf expansion and kept a relatively constant value in the later periods, which was mainly due to the rapid expansion of epidermal cells. Secondly, the total number of glands per leaf showed a reversed trend compared to the density of salt glands. These results suggested that the salt gland density was adapted to the leaf age and area as more and more salt accumulated in the saline soils.

Overexpression of a novel soybean gene modulating Na+ and K+ transport enhances salt tolerance in transgenic tobacco plants.

PubMed

Chen, Huatao; He, Hui; Yu, Deyue

2011-01-01

Salt is an important factor affecting the growth and development of soybean in saline soil. In this study, a novel soybean gene encoding a transporter (GmHKT1) was identified and its function analyzed using transgenic plants. GmHKT1 encoded a protein of 419 amino acids, with a potential molecular mass of 47.06 kDa and a predicted pI value of 8.59. Comparison of the genomic and cDNA sequences of GmHKT1 identified no intron. The deduced amino acid sequence of GmHKT1 showed 38-49% identity with other plant HKT-like sequences. RT-PCR analysis showed that the expression of GmHKT1 was upregulated by salt stress (150 mM NaCl) in roots and leaves but not in stems. Overexpression of GmHKT1 significantly enhanced the tolerance of transgenic tobacco plants to salt stress, compared with non-transgenic plants. To investigate the role of GmHKT1 in K(+) and Na(+) transport, we compared K(+) and Na(+) accumulation in roots and shoots of wild-type and transgenic tobacco plants. The results suggested that GmHKT1 is a transporter that affected K(+) and Na(+) transport in roots and shoots, and regulated Na(+) /K(+) homeostasis in these organs. Our findings suggest that GmHKT1 plays an important role in response to salt stress and would be useful in engineering crop plants for enhanced tolerance to salt stress. Copyright © Physiologia Plantarum 2010.

Comparative analysis of alfalfa (Medicago sativa L.) leaf transcriptomes reveals genotype-specific salt tolerance mechanisms.

PubMed

Lei, Yunting; Xu, Yuxing; Hettenhausen, Christian; Lu, Chengkai; Shen, Guojing; Zhang, Cuiping; Li, Jing; Song, Juan; Lin, Honghui; Wu, Jianqiang

2018-02-15

Soil salinity is an important factor affecting growth, development, and productivity of almost all land plants, including the forage crop alfalfa (Medicago sativa). However, little is known about how alfalfa responds and adapts to salt stress, particularly among different salt-tolerant cultivars. Among seven alfalfa cultivars, we found that Zhongmu-1 (ZM) is relatively salt-tolerant and Xingjiang Daye (XJ) is salt-sensitive. Compared to XJ, ZM showed slower growth under low-salt conditions, but exhibited stronger tolerance to salt stress. RNA-seq analysis revealed 2237 and 1125 differentially expressed genes (DEGs) between ZM and XJ in the presence and absence of salt stress, among which many genes are involved in stress-related pathways. After salt treatment, compared with the controls, the number of DEGs in XJ (19373) was about four times of that in ZM (4833). We also detected specific differential gene expression patterns: In response to salt stress, compared with XJ, ZM maintained relatively more stable expression levels of genes related to the ROS and Ca 2+ pathways, phytohormone biosynthesis, and Na + /K + transport. Notably, several salt resistance-associated genes always showed greater levels of expression in ZM than in XJ, including a transcription factor. Consistent with the suppression of plant growth resulting from salt stress, the expression of numerous photosynthesis- and growth hormone-related genes decreased more dramatically in XJ than in ZM. By contrast, the expression levels of photosynthetic genes were lower in ZM under low-salt conditions. Compared with XJ, ZM is a salt-tolerant alfalfa cultivar possessing specific regulatory mechanisms conferring exceptional salt tolerance, likely by maintaining high transcript levels of abiotic and biotic stress resistance-related genes. Our results suggest that maintaining this specific physiological status and/or plant adaptation to salt stress most likely arises by inhibition of plant growth in ZM through

Variable Charge Soils: Mineralogy and Chemistry

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

Qafoku, Nik; Van Ranst, Eric; Noble, Andrew

2003-11-01

developed on ferromagnesian-rich parent materials) the surfaces of phyllosilicates are coated to a lesser or greater extent by amorphous or crystalline, oppositely charged nanoparticles of Fe and Al oxides. These coatings exhibit a high reactive surface area and help cementing larger particles with one another. As a result of these electrostatic interactions, stable microaggregates that are difficult to disperse are formed in variable charge soils. Most of highly weathered soils have reached the “advanced stage” of Jackson-Sherman weathering sequence that is characterized by the removal of Na, K, Ca, Mg, and Fe(II), the presence of Fe and Al polymers, and very dilute soil solutions with an ionic strength (IS) of less than 1 mmol L-1. The inter-penetration or overlapping of the diffuse double layers on oppositely charged surfaces may occur in these dilute systems. These diffuse layer interactions may affect the magnitude of the effective charge, i.e., the counter-ion charge (4). In addition, salt adsorption, which is defined as the simultaneous adsorption in equivalent amounts of the cation and anion of an electrolyte with no net release of other ions into the soil solution, appears to be a common phenomenon in these soils. They act as cation- and anion-exchangers and as salt-sorbers. The magnitude of salt adsorption depends strongly on initial IS in the soil solution and the presence in appreciable amounts of oppositely charged surfaces. Among the authors that have made illustrious contributions towards a better understanding of these fascinating soil systems are S. Matson, R.K. Schofield, van Olphen, M.E. Sumner, G.W. Thomas, G.P. Gillman, G. Uehara, B.K.G. Theng, K. Wada, N.J. Barrow, J.W. Bowden, R.J. Hunter and G. Sposito. This entry is mainly based on publications by these authors.« less

Growth platform-dependent and -independent phenotypic and metabolic responses of Arabidopsis and its halophytic relative, Eutrema salsugineum, to salt stress.

PubMed

Kazachkova, Yana; Batushansky, Albert; Cisneros, Aroldo; Tel-Zur, Noemi; Fait, Aaron; Barak, Simon

2013-07-01

Comparative studies of the stress-tolerant Arabidopsis (Arabidopsis thaliana) halophytic relative, Eutrema salsugineum, have proven a fruitful approach to understanding natural stress tolerance. Here, we performed comparative phenotyping of Arabidopsis and E. salsugineum vegetative development under control and salt-stress conditions, and then compared the metabolic responses of the two species on different growth platforms in a defined leaf developmental stage. Our results reveal both growth platform-dependent and -independent phenotypes and metabolic responses. Leaf emergence was affected in a similar way in both species grown in vitro but the effects observed in Arabidopsis occurred at higher salt concentrations in E. salsugineum. No differences in leaf emergence were observed on soil. A new effect of a salt-mediated reduction in E. salsugineum leaf area was unmasked. On soil, leaf area reduction in E. salsugineum was mainly due to a fall in cell number, whereas both cell number and cell size contributed to the decrease in Arabidopsis leaf area. Common growth platform-independent leaf metabolic signatures such as high raffinose and malate, and low fumarate contents that could reflect core stress tolerance mechanisms, as well as growth platform-dependent metabolic responses were identified. In particular, the in vitro growth platform led to repression of accumulation of many metabolites including sugars, sugar phosphates, and amino acids in E. salsugineum compared with the soil system where these same metabolites accumulated to higher levels in E. salsugineum than in Arabidopsis. The observation that E. salsugineum maintains salt tolerance despite growth platform-specific phenotypes and metabolic responses suggests a considerable degree of phenotypic and metabolic adaptive plasticity in this extremophile.

Phosphorus geochemistry in a Brazilian semiarid mangrove soil affected by shrimp farm effluents.

PubMed

Nóbrega, G N; Otero, X L; Macías, F; Ferreira, T O

2014-09-01

Wastewater discharge from shrimp farming is one of the main causes of eutrophication in mangrove ecosystems. We investigated the phosphorus (P) geochemistry in mangrove soils affected by shrimp farming effluents by carrying out a seasonal study of two mangrove forests (a control site (CS); a site affected by shrimp farm effluents (SF)). We determined the soil pH, redox potential (Eh), total organic carbon (TOC), total phosphorus (TP), and dissolved P. We also carried out sequential extraction of the P-solid phases. In SF, the effluents affected the soil physicochemical conditions, resulting in lower Eh and higher pH, as well as lower TOC and higher TP than in CS. Organic P forms were dominant in both sites and seasons, although to a lesser extent in SF. The lower TOC in SF was related to the increased microbial activity and organic matter decomposition caused by fertilization. The higher amounts of P oxides in SF suggest that the effluents alter the dominance of iron and sulfate reduction in mangrove soils, generating more reactive Fe that is available for bonding to phosphates. Strong TP losses were recorded in both sites during the dry season, in association with increased amounts of exchangeable and dissolved P. The higher bioavailability of P during the dry season may be attributed to increased mineralization of organic matter and dissolution of Ca-P in response to more oxidizing and acidic conditions. The P loss has significant environmental implications regarding eutrophication and marine productivity.

Soil temperature and precipitation affect the rooting ability of dormant hardwood cuttings of Populus

Treesearch

R.S., Jr. Zalesny; R.B. Hall; E.O. Bauer; D.E. Riemenschneider

2005-01-01

In addition to genetic control, responses to environmental stimuli affect the success of rooting. Our objectives were to: 1) assess the variation in rooting ability among 21 Populus clones grown under varying soil temperatures and amounts of precipitation and 2) identify combinations of soil temperature and precipitation that promote rooting. The...

Temporal and Spatial Dynamics of Carbon Storage in California Coastal Salt Marshes

NASA Astrophysics Data System (ADS)

Brown, L. N.; MacDonald, G. M.

2016-12-01

Coastal salt marshes rank as one of the ecosystems which sequester the most carbon (C) in the world (Chmura, 2003; Mcleod et al., 2011). California hosts multiple small marsh ecosystems outside of the San Francisco Bay that are limited in geographic extent but still contribute significantly to global soil C. We have collected over 100 sediment cores from 11 coastal marsh sites from Humboldt Bay to Tijuana River Estuary on the coast of California. Our 100 cm depth cores cover high, mid, and low elevations in the coastal salt marsh ecosystem, which are known to sequester carbon with varying rates. Approximately 40 cores of the 100 collected cores have been selected for detailed chronologic and stratigraphic analysis, 3 cores at each site minimum. Chronologies are established using 14C, 137Cs, and 210Pb. Our study estimates a carbon sequestration rate of 49 g C m-2 yr-1 for California over the past 100 years. These results are consistent with other long term estimates of soil C, which generally are lower because of natural decomposition of organic C, but also reinforces long-term persistence of soil C in salt marshes over time. These estimates provide valuable proof of the long-term capacity and spatial variability of C sequestration in coastal salt marshes of California.

Environmental factors affecting corrosion of munitions

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

Bundy, K.; Bricka, M.; Morales, A.

1995-12-31

Spent small arms munitions have accumulated for years at outdoor firing ranges operated by the DoD and other groups. Used bullets are often subjected to moisture sources. There is increasing concern that accumulations of lead-based munitions represent potential sources of water and soil pollution. To understand both the severity of and solutions to this problem, it is necessary to measure how rapidly bullets corrode and to determine the soil variables affecting the process. In this study M16 bullets were buried in samples of soil taken from Louisiana army firing ranges. Four environmental conditions were simulated; rain water, acid rain, seamore » water, and 50% sea water/50% acid rain. The three electrode technique was used to measure the bullet corrosion. Graphite rods served as counter electrodes. A saturated calomel reference electrode was used along with a specially constructed salt bridge. Electrochemical measurements were conducted using a computer-controlled potentiostat to determine corrosion potential, soil resistance, and corrosion current. The rate of corrosion was found to markedly increase with decreasing soil pH and increasing chloride and moisture contents, with the chloride content being the most influential variable. High soil resistance and noble corrosion potential were found to be associated with low corrosion rates. This is important since both parameters can be readily measured in the field.« less

Soil Porewater Salinity Response to Sea-level Rise in Tidal Freshwater Forested Wetlands: A Modeling Study

NASA Astrophysics Data System (ADS)

Stagg, C. L.; Wang, H.; Krauss, K.; Conrads, P. A.; Swarzenski, C.; Duberstein, J. A.; DeAngelis, D.

2017-12-01

There is a growing concern about the adverse effects of salt water intrusion via tidal rivers and creeks into tidal freshwater forested wetlands (TFFWs) due to rising sea levels and reduction of freshwater flow. The distribution and composition of plant species, vegetation productivity, and biogeochemical functions including carbon sequestration capacity and flux rates in TFFWs have been found to be affected by increasing river and soil porewater salinities, with significant shifts occurring at a porewater salinity threshold of 3 PSU. However, the drivers of soil porewater salinity, which impact the health and ecological functions of TFFWs remains unclear, limiting our capability of predicting the future impacts of saltwater intrusion on ecosystem services provided by TFFWs. In this study, we developed a soil porewater salinity model for TFFWs based on an existing salt and water balance model with modifications to several key features such as the feedback mechanisms of soil salinity on evapotranspiration reduction and hydraulic conductivity. We selected sites along the floodplains of two rivers, the Waccamaw River (SC, USA) and the Savannah River (GA and SC, USA) that represent landscape salinity gradients of both surface water and soil porewater from tidal influence of the Atlantic Ocean. These sites represent healthy, moderately and highly salt-impacted forests, and oligohaline marshes. The soil porewater salinity model was calibrated and validated using field data collected at these sites throughout 2008-2016. The model results agreed well with field measurements. Analyses of the preliminary simulation results indicate that the magnitude, seasonal and annual variability, and duration of threshold salinities (e.g., 3 PSU) tend to vary significantly with vegetation status and type (i.e., healthy, degraded forests, and oligohaline marshes), especially during drought conditions. The soil porewater salinity model could be coupled with a wetland soil biogeochemistry

Dynamic chemical characteristics of soil solution after pig manure application: a column study.

PubMed

Hao, Xiuzhen; Zhou, Dongmei; Sun, Lei; Li, Lianzhen; Zhang, Hailin

2008-06-01

When manures from intensive livestock operations are applied to agricultural or vegetable fields at a high rate, large amounts of salts and metals will be introduced into soils. Using a column leaching experiment, this study assessed the leaching potential of the downward movement of Cu and Zn as well as some salt ions after an intensive farm pig manure at rates of 0%, 5% and 10% (w/w) were applied to the top 20 cm of two different textured soils (G soil -sandy loam soil; H soil-silty clay loam soil), and investigated the growth of amaranth and Cu and Zn transfer from soil to amaranth (Amaranthus tricolor). Soil solutions were obtained at 20, 40 and 60 cm depth of the packed column and analyzed for pH, electrical conductivity (EC), dissolved organic matter (DOC) and Cu and Zn concentrations. The results indicated that application of pig manure containing Cu and Zn to sandy loam soil might cause higher leaching and uptake risk than silty clay loam soil, especially at high application rates. And manure amendment at 5% and 10% significantly decreased the biomass of amaranth, in which the salt impact rather than Cu and Zn toxicity from manures played more important role in amaranth growth. Thus the farmer should avoid application the high rate of pig manure containing metal and salt to soil at a time, especially in sandy soil.

Biological soil crusts: a microenvironment characterized by complex microbial interrelations affected by the presence of the exopolysaccharidic matrix.

NASA Astrophysics Data System (ADS)

De Philippis, Roberto

2015-04-01

Biological Soil Crusts (BSCs) are complex microbial communities, commonly found in arid and semiarid areas of the world. The capability of the microorganisms residing in BSCs to withstand the harsh environmental conditions typical of these habitats, namely drought and high solar irradiation, is related with the presence of a matrix constituted by microbial-produced extracellular polysaccharides (EPSs), which also accomplish for a wide array of key ecological roles. EPSs represent a huge carbon source directly available to heterotrophic organisms, affect soil characteristics, water regimes, and establish complex interactions with plants. The induction of BSCs on degraded soils is considered a feasible approach to amend and maintain land fertility, as it was reported in a number of recent studies. It was recently shown that BSC induction is beneficial in enhancing SOC (Soil Organic Carbon) and in increasing the abundance of phototrophic organisms and vegetation cover. This lecture will describe the results of a study showing that cyanobacterial-EPS resulted advantageous to the growth and metabolism of seedlings of Caragana korshinskii, a desert sub-shrub widely diffused in the area under study, also contributing a defensive effect against the damaging effects of reactive oxygen species (ROS), generated under UV-irradiation, salt stress and desiccation. A study aimed at investigating the possible correlation between the chemical composition and the macromolecular features of the EPS matrix of induced BSCs of different age, collected in the hyper-arid plateau of Hobq desert, Inner Mongolia, China, will be also presented. The results of this study showed that the characteristics of the EPS of the matrix of the investigated IBSCs cannot be put only in relation with the age of the crusts and the activity of phototrophic microorganisms but, more properly, it has to be taken into account the biotic interactions ongoing between EPS producers (cyanobacteria, green microalgae

Do root traits affect a plant's ability to influence soil erosion?

NASA Astrophysics Data System (ADS)

Burak, Emma; Quinton, John; Dodd, Ian

2017-04-01

With the ever increasing global population the agricultural sector is put under increasing pressure. This pressure is imposed on the soil and results in wide spread degradation that ultimately decreases productivity. Soil erosion is one of the main features of this degradation. Much focus has been put on the ability of plant canopies to mitigate soil erosion but little research has assessed the impact of below ground biomass. It is understood that woody roots reinforce slopes and lateral roots are believed to support the soil surface but the impact of root hairs is completely unknown. This study used two root hairless mutants one of barley (brb) and one of maize (rth3) along with their wild types (WT) to assess the capacity of different root traits to bind soil particles to the root system, creating a physical coating called a rhizosheath. The two genotypes were grown in a clay loam and periodically harvested during vegetative development. Rhizosheath weight was used to measure the ability of the root system to effectively bind soil particles, while root length was measured to standardise the results between genotypes. Overall, rhizosheath weight increased linearly with root length. When compared to WT plants of the same age, the root length of brb was, on average, 37% greater, suggesting that they compensated for the absence of root hairs by proliferating lateral roots. However, WT plants were far superior at binding soil particles as the rhizosheath weights were 5 fold greater, when expressed per unit root length. Thus root hairs are more important in binding soil particles than lateral roots. Whether these genotypic differences in root traits affect soil erosion will be assessed using mesocosm and field trials. Keywords: Soil erosion, Roots, Barley, Rhizosheath