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Redox-dependent effects of phosphate on arsenic speciation in paddy soils
2020
Deng, Yingxuan | Weng, Liping | Li, Yongtao | Chen, Yali | Ma, Jie
Evaluating speciation of arsenic (As) is essential to assess its risk in paddy soils. In this study, effects of phosphate on speciation of As in six paddy soils differing in redox status were studied over a range of pH (pH 3-9) and different background calcium (Ca) levels by batch adsorption experiments and speciation modeling. Contrasting effects of phosphate on As speciation were observed in suboxic and anoxic soils. Under suboxic conditions, phosphate inhibited Fe and As reduction probably due to stabilization of Fe-(hydr)oxides, but increased soluble As(V) concentration as a result of competitive adsorption between As(V) and phosphate. In anoxic soils, phosphate stimulated Fe and As reduction and caused increases of As(III) in soil solution under both acidic and neutral/alkaline pH. The LCD (Ligand and Charge Distribution) and NOM-CD (Natural Organic Matter-Charge Distribution) model can describe effects of pH, calcium and phosphate on As speciation in these paddy soils. The results suggest that phosphatefertilization may decrease (at low pH) or increase (at neutral/alkaline pH) As mobility in paddy soils under (sub)oxic conditions, but under anoxic conditions and in phosphorus deficient soils phosphate fertilization may strongly mobilize As by promoting microbial activities.
Show more [+] Less [-]Redox-dependent effects of phosphate on arsenic speciation in paddy soils
2020
Deng, Yingxuan | Weng, Liping | Li, Yongtao | Chen, Yali | Ma, Jie
Evaluating speciation of arsenic (As) is essential to assess its risk in paddy soils. In this study, effects of phosphate on speciation of As in six paddy soils differing in redox status were studied over a range of pH (pH 3-9) and different background calcium (Ca) levels by batch adsorption experiments and speciation modeling. Contrasting effects of phosphate on As speciation were observed in suboxic and anoxic soils. Under suboxic conditions, phosphate inhibited Fe and As reduction probably due to stabilization of Fe-(hydr)oxides, but increased soluble As(V) concentration as a result of competitive adsorption between As(V) and phosphate. In anoxic soils, phosphate stimulated Fe and As reduction and caused increases of As(III) in soil solution under both acidic and neutral/alkaline pH. The LCD (Ligand and Charge Distribution) and NOM-CD (Natural Organic Matter-Charge Distribution) model can describe effects of pH, calcium and phosphate on As speciation in these paddy soils. The results suggest that phosphatefertilization may decrease (at low pH) or increase (at neutral/alkaline pH) As mobility in paddy soils under (sub)oxic conditions, but under anoxic conditions and in phosphorus deficient soils phosphate fertilization may strongly mobilize As by promoting microbial activities.
Show more [+] Less [-]Tracking the Transport of Silver Nanoparticles in Soil : a Saturated Column Experiment
2018
Mahdi, Karrar N.M. | Peters, Ruud | Ploeg, van der, Martine | Ritsema, Coen | Geissen, Violette
Silver nanoparticles (AgNPs) can enter the environment when released from products containing them. As AgNPs enter soil, they are often retained in the soil profile and/or leached to the groundwater. This research assessed the transport of AgNPs in their “particle form” through the soil profile using a series of columns. Three soil types were put into soil columns: LSH (loam with high organic matter (OM)), LSL (loam with low OM), and Sand (no OM). The results showed that AgNP transport and retention in soil as well as particle size changes are affected by soil organic matter (OM) and the cation exchange capacity (CEC) of soil. OM affected the transport and retention of AgNPs. This was evident in the LSH columns where the OM concentration was the highest and the AgNP content the lowest in the soil layers and in the effluent water. The highest transported AgNP content was detected in the Sand columns where OM was the lowest. CEC had an impact on the particle size of the AgNPs that were retained in the soil layers. This was clear in columns packed with high CEC-containing soils (LSL and LSH) where AgNP particle size decreased more substantially than in the columns packed with sand. However, the decrease in AgNP sizes in the effluent water was less than the decrease in particle size of AgNPs transported through but retained in the soil. This means that the AgNPs that reached the effluent were transported directly from the first layer through the soil macropores. This work highlights the ability to track AgNPs at low concentrations (50 μg kg<sup>−1</sup>) and monitor the changes in particle size potential as the particles leach through soil all of which increases our knowledge about AgNP transport mechanisms in porous media.
Show more [+] Less [-]Nitrogen cycling in two Norway spruce (Picea abies) ecosystems and effects of a (NH4)2SO4 addition
1992
Feger, K.H. (Albert-Ludwig-University, Freiburg (Germany). Inst. of Soil Science and Forest Nutrition)
SO2 and NH3 deposition as possible causes for the extinction of Arnica montana L.
1992
Fennema, F. (Rijksinstituut voor Natuurbeheer, Arnhem (Netherlands))
Nutritional status of declining spruce (Picea abies (L.) Karst.): effect of soil organic matter turnover rate
1991
Hambuckers, A. (Liege Univ. (Belgium). Dept. of Microbial Ecology) | Remacle, J.
Effect of the herbicide glyphosate on respiration and hydrogen consumption in soil
1985
Carlisle, S.M. (Guelph Univ., Ontario (Canada). Dept. of Environmental Biology) | Trevors, J.T.
Effects of air pollutants on mineral nutrition of Norway spruce and revitalization of declining stands in Austria
1992
Katzensteiner, K. (Universitaet fuer Bodenkultur, Vienna (Austria). Inst. of Forest Ecology) | Glatzel, G. | Kazda, M. | Sterba, H.
Behavior of phenol and aniline on selected sorbents and energy-related solid wastes
1990
Bishop, D.J. (Lawrence Livermore National Lab., Livermore, CA (USA). Environmental Sciences Div.) | Knezovich, J.P. | Harrison, F.L.
Soil nutrient leaching in response to simulated acid rain treatment
1987
Kelly, J.M. (Tennessee Valley Authority, Muscle Shoals, AL (USA). Div. of Air and Water Resources, Air Quality Branch) | Strickland, R.C.