Uncertainly analysis of the nonideal competitive adsorption-Donnan model: effects of dissolved organic matter vaiability on predicted metal speciation in soil solution.
Groenenberg, J.E. ; Koopmans, G.F. ; Comans, R.N.J. - \ 2010
Environmental Science and Technology 44 (2010)4. - ISSN 0013-936X - p. 1340 - 1346.
humic substances - fresh-waters - heavy-metals - ion-binding - sandy soil - cu - complexation - pb - parameters - acids
Ion binding models such as the nonideal competitive adsorption-Donnan model (NICA-Donnan) and model VI successfully describe laboratory data of proton and metal binding to purified humic substances (HS). In this study model performance was tested in more complex natural systems. The speciation predicted with the NICA-Donnan model and the associated uncertainty were compared with independent measurements in soil solution extracts, including the free metal ion activity and fulvic (FA) and humic acid (HA) fractions of dissolved organic matter (DOM). Potentially important sources of uncertainty are the DOM composition and the variation in binding properties of HS. HS fractions of DOM in soil solution extracts varied between 14 and 63% and consisted mainly of FA. Moreover, binding parameters optimized for individual FA samples show substantial variation. Monte Carlo simulations show that uncertainties in predicted metal speciation, for metals with a high affinity for FA (Cu, Pb), are largely due to the natural variation in binding properties (i.e., the affinity) of FA. Predictions for metals with a lower affinity (Cd) are more prone to uncertainties in the fraction FA in DOM and the maximum site density (i.e., the capacity) of the FA. Based on these findings, suggestions are provided to reduce uncertainties in model predictions
Transfer functions for solid-solution partitioning of cadmium, copper, nickel, lead and zinc in soils: derivation of relationships for free metal ion activities and validation with independent data
Groenenberg, J.E. ; Römkens, P.F.A.M. ; Comans, R.N.J. ; Luster, J. ; Pampura, T. ; Shotbolt, L. ; Tipping, E. ; Vries, W. de - \ 2010
European Journal of Soil Science 61 (2010)1. - ISSN 1351-0754 - p. 58 - 73.
dissolved organic-matter - donnan membrane technique - contaminated soils - heavy-metals - sandy soil - chemical speciation - trace-metals - pore-water - ph - cu
Models to predict the solid-solution partitioning of trace metals are important tools in risk assessment, providing information on the biological availability of metals and their leaching. Empirically based models, or transfer functions, published to date differ with respect to the mathematical model used, the optimization method, the methods used to determine metal concentrations in the solid and solution phases and the soil properties accounted for. Here we review these methodological aspects before deriving our own transfer functions that relate free metal ion activities to reactive metal contents in the solid phase. One single function was able to predict free-metal ion activities estimated by a variety of soil solution extraction methods. Evaluation of the mathematical formulation showed that transfer functions derived to optimize the Freundlich adsorption constant (Kf), in contrast to functions derived to optimize either the solid or solution concentration, were most suitable for predicting concentrations in solution from solid phase concentrations and vice versa. The model was shown to be generally applicable on the basis of a large number of independent data, for which predicted free metal activities were within one order of magnitude of the observations. The model only over-estimated free-metal ion activities at alkaline pH (>7). The use of the reactive metal content measured by 0.43 m HNO3 rather than the total metal content resulted in a close correlation with measured data, particularly for nickel and zinc
Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning
Römkens, P.F.A.M. ; Guo, H.Y. ; Chu, C.L. ; Liu, T.S. ; Chiang, C.F. ; Koopmans, G.F. - \ 2009
Journal of Soils and Sediments 9 (2009)3. - ISSN 1439-0108 - p. 216 - 228.
contaminated soils - flow-analysis - trace-metals - cadmium - rice - cd - cu - zinc - zn - pb
Ongoing industrialization has resulted in an accumulation of metals like Cd, Cu, Cr, Ni, Zn, and Pb in paddy fields across Southeast Asia. Risks of metals in soils depend on soil properties and the availability of metals in soil. At present, however, limited information is available on how to measure or predict the directly available fraction of metals in paddy soils. Here, the distribution of Cd, Cu, Cr, Ni, Zn, and Pb in 19 paddy fields among the total, reactive, and directly available pools was measured using recently developed concepts for aerated soils. Solid-solution partitioning models have been derived to predict the directly available metal pool. Such models are proven to be useful for risk assessment and to derive soil quality standards for aerated soils. Soil samples (0-25 cm) were taken from 19 paddy fields from five different communities in Taiwan in 2005 and 2006. Each field was subdivided into 60 to 108 plots resulting in a database of approximately 3,200 individual soil samples. Total (Aqua Regia (AR)), reactive (0.43 M HNO3, 0.1 M HCl, and 0.05 M EDTA), and directly available metal pools (0.01 M CaCl2) were determined. Solid-solution partitioning models were derived by multiple linear regressions using an extended Freundlich equation using the reactive metal pool, pH, and the cation exchange capacity (CEC). The influence of Zn on metal partitioning and differences between both sampling events (May/November) were evaluated. Total metals contents range from background levels to levels in excess of current soil quality standards for arable land. Between 3% (Cr) and 30% (Cd) of all samples exceed present soil quality standards based on extraction with AR. Total metal levels decreased with an increasing distance from the irrigation water inlet. The reactive metal pool relative to the total metal content is increased in the order Cr
Tree species effect on the redistribution of soil metals
Mertens, J. ; Nevel, L. Van; Schrijver, A. De; Piesschaert, F. ; Oosterbaan, A. ; Tack, F.M.G. ; Verheyen, K. - \ 2007
Environmental Pollution 149 (2007)2. - ISSN 0269-7491 - p. 173 - 181.
disposed dredged sediments - contaminated soils - temperate forests - heavy-metals - litter - land - cd - zn - cu - ecosystem
Phytostabilization of metals using trees is often promoted although the influence of different tree species on the mobilization of metals is not yet clear. Soil and biomass were sampled 33 years after planting four tree species (Quercus robur, Fraxinus excelsior, Acer pseudoplatanus, Populus `Robusta¿) in a plot experiment on dredged sediment. Poplar took up high amounts of Cd and Zn and this was associated with increased Cd and Zn concentrations in the upper soil layer. The other species contained normal concentrations of Cd, Cu, Cr, Pb and Zn in their tissues. Oak acidified the soil more than the other species and caused a decrease in the concentration of metals in the upper soil layer. The pH under poplar was lower than expected and associated with high carbon concentrations in the top soil. This might be assigned to retardation of the litter decomposition due to elevated Cd and Zn concentrations in the litter. Trees (33-year-old) growing on polluted dredged sediment have influenced the metal concentration in the upper soil layer and there was a significant tree species effect.
Mobilization of heavy metals from contaminated paddy soil by EDDS, EDTA, and elemental sulfur
Wang, G. ; Koopmans, G.F. ; Song, J. ; Temminghoff, E.J.M. ; Luo, Y. ; Zhao, Q. ; Japenga, J. - \ 2007
Environmental Geochemistry and Health 29 (2007)3. - ISSN 0269-4042 - p. 221 - 235.
disuccinic acid edds - enhanced phytoextraction - lead phytoextraction - chelating-agents - phytoremediation - biodegradation - extraction - pb - cu - accumulation
For enhanced phytoextraction, mobilization of heavy metals (HMs) from the soil solid phase to soil pore water is an important process. A pot incubation experiment mimicking field conditions was conducted to investigate the performance of three soil additives in mobilizing HMs from contaminated paddy soil (Gleyi-Stagnic Anthrosol): the [S, S]-isomer of ethylenediamine disuccinate (EDDS) with application rates of 2.3, 4.3, and 11.8 mmol kg¿1 of soil, ethylenediamine tetraacetate (EDTA; 1.4, 3.8, and 7.5 mmol kg¿1), and elemental sulfur (100, 200, and 400 mmol kg¿1). Temporal changes in soil pore water HM and dissolved organic carbon concentrations and pH were monitored for a period of 119 days. EDDS was the most effective additive in mobilizing soil Cu. However, EDDS was only effective during the first 24 to 52 days, and was readily biodegraded with a half-life of 4.1 to 8.7 days. The effectiveness of EDDS decreased at the highest application rate, most probably as a result of depletion of the readily desorbable Cu pool in soil. EDTA increased the concentrations of Cu, Pb, Zn, and Cd in the soil pore water, and remained effective during the whole incubation period due to its persistence. The highest rate of sulfur application led to a decrease in pH to around 4. This increased the pore water HM concentrations, especially those of Zn and Cd. Concentrations of HMs in the soil pore water can be regulated to a large extent by choosing the proper application rate of EDDS, EDTA, or sulfur. Hence, a preliminary work such as our pot experiment in combination with further plant experiments (not included in this study) will provide a good tool to evaluate the applicability of different soil additives for enhanced phytoextraction of a specific soil.
Uptake and distribution of root-applied or foliar-applied 65Zn after flowering in aerobic rice
Jiang, W. ; Struik, P.C. ; Lingna, J. ; Keulen, H. van; Ming, Z. ; Stomph, T.J. - \ 2007
Annals of Applied Biology 150 (2007)3. - ISSN 0003-4746 - p. 383 - 391.
developing wheat grains - zinc uptake - zn - plants - accumulation - manganese - iron - cu - phytoremediation - nutrition
We investigated the uptake and distribution of zinc (Zn) either applied to the roots or to the leaves in rice during grain development. Plants of two aerobic rice cultivars were grown in a nutrient solution with either sufficient Zn or surplus Zn. Root treatment with 1 week`s supply of both 65Zn and unlabelled Zn was started at flowering or 15 days after flowering (DAF). Foliar treatment with 65Zn applied to the flag leaf or to senescent leaves was carried out at flowering. When 65Zn was applied to roots, plants continued to take up Zn after flowering, even beyond 15 DAF, irrespective of cultivar and Zn nutritional status of the plants. During the 1 week of supply of both 65Zn and unlabelled Zn, which either started at flowering or 15 DAF, the absorbed 65Zn was mainly distributed to roots, stem and grains. Little 65Zn was allocated to the leaves. Following a week of 65Zn supply directly after flowering, under sufficient Zn or surplus Zn, the proportions of total 65Zn uptake allocated to the grains continued to change during grain filling (9¿33%). This Zn mainly came from the roots but under sufficient Zn supply also from the stem. With 65Zn applied to leaves (either the flag leaf or the lowest senescent leaf), both cultivars showed similar Zn distribution within the plants. About 45¿50% of the 65Zn absorbed was transported out of the 65Zn-treated leaf. From that Zn, more than 90% was translocated to other vegetative organs; little was partitioned to the panicle parts and even less to the grains. These results suggest that in rice plants grown under sufficient or surplus Zn supply, most of the Zn accumulated in the grains originates from uptake by roots after flowering and not from Zn remobilisation from leaves
The effect of long-term irrigation using wastewater on heavy metal contents of soils under vegetables in Harare, Zimbabwe
Mapanda, F. ; Mangwayana, E.N. ; Nyamangara, J. ; Giller, K.E. - \ 2005
Agriculture, Ecosystems and Environment 107 (2005)2-3. - ISSN 0167-8809 - p. 151 - 165.
sewage-sludge - effluent - zn - ni - cu
The magnitude of contamination, regulatory compliance and annual loadings of soils with copper (Cu), zinc (Zn), cadmium (Cd), nickel (Ni), chromium (Cr) and lead (Pb) were determined at three sites in Harare where wastewater was used to irrigate vegetable gardens for at least 10 years. Heavy metal total concentrations (mg kg-1) in sandy and sandy–clay soils of pH 5.1–8.1 from all sites ranged from 7.0 to 145 for Cu, 14 to 228 for Zn, 0.5 to 3.4 for Cd,