Details
| Original language | English |
|---|---|
| Pages (from-to) | 44-54 |
| Number of pages | 11 |
| Journal | GEODERMA |
| Volume | 300 |
| Early online date | 25 Apr 2017 |
| Publication status | Published - 15 Aug 2017 |
Abstract
Copper is a redox-sensitive trace element, which can be both, an essential micronutrient and a pollutant. We therefore analyzed Cu concentrations and stable isotope ratios (δ 65Cu values) in a drained Retisol to trace the response of Cu to a changing hydrological regime and enhanced clay eluviation. The study soil was artificially drained 16years before sampling resulting in macroscopically visible pedogenetic changes and is thus a suitable site to investigate the influence of pedogenetic processes on the fate of Cu. Samples were collected from all horizons along a trench at four distances from the drain: 0.6m, 1.1m, 2.1m and 4.0m. In the E&Bt horizon, four different soil volumes (ochre, pale brown, white-grey and black) were sampled at all four distances from the drain. Furthermore, we analyzed soil solutions sampled with piezometer, porous cups, and at the drain outlet. The Cu concentrations were lowest in the surface (Ap) horizons (6.5–8.5μgg −1) and increased with depth to the clay-rich Bt horizons (10.5–12μgg −1), because of clay eluviation and associated Cu transport. The δ 65Cu values significantly decreased from the surface (Ap=−0.25±0.07‰) to the deeper horizons, but showed no significant variation among the deeper horizons (−0.41±0.28‰) and no correlation with the clay content, indicating that clay eluviation did not significantly affect δ 65Cu values. The isotopically heavier δ 65Cu values in the Ap horizons can probably be explained by agricultural management practices like sludge application and fertilization. Close to the drain (position 0.6m), Cu concentrations were depleted and the lighter Cu isotope was enriched (−0.91±0.15‰) in the uppermost part of the E&Bt horizon. We attribute this to the changing redox conditions, caused by the lowering of the water level close to the drain. Copper concentrations in black and ochre volumes were significantly higher than in pale-brown and white-grey volumes. The black volume had significantly higher δ 65Cu values than the ochre volume indicating preferential sorption/occlusion of the heavy Cu isotope by Fe oxides. Enhanced clay eluviation in bulk soil close to the drain and in specific soil volumes did not affect δ 65Cu values. Cu concentrations (2.1–14μgL −1) and δ 65Cu (0.04–0.42‰) values in water samples showed no clear relation with redox changes along the trench perpendicular to the drain. The enrichment of the heavy Cu isotope in the solution samples (Δ 65Cu (soil-solution)=−0.61±0.41) indicates that reductive Cu mobilization is not the main driver of Cu leaching, because this would preferentially mobilize isotopically light Cu. We conclude that the eluviation of the <2μm fraction, strongly controlled Cu concentrations, but had no discernible effect on δ 65Cu values. The changing redox conditions did not seem to control Cu concentrations and the stable isotope distribution in most of the bulk soil, soil volumes and soil water. Instead, weathering, complexation of leached Cu, Cu application with fertilizers and sorption processes within the soil controlled its δ 65Cu values.
Keywords
- Copper isotopes, Drainage, Lessivation, Redox conditions, Retisol, Soil volumes, Soil water
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Soil Science
Sustainable Development Goals
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In: GEODERMA, Vol. 300, 15.08.2017, p. 44-54.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Response of copper concentrations and stable isotope ratios to artificial drainage in a French Retisol
AU - Kusonwiriyawong, C.
AU - Bigalke, M.
AU - Cornu, S.
AU - Montagne, D.
AU - Fekiacova, Z.
AU - Lazarov, M.
AU - Wilcke, W.
N1 - Publisher Copyright: © 2017 Elsevier B.V.
PY - 2017/8/15
Y1 - 2017/8/15
N2 - Copper is a redox-sensitive trace element, which can be both, an essential micronutrient and a pollutant. We therefore analyzed Cu concentrations and stable isotope ratios (δ 65Cu values) in a drained Retisol to trace the response of Cu to a changing hydrological regime and enhanced clay eluviation. The study soil was artificially drained 16years before sampling resulting in macroscopically visible pedogenetic changes and is thus a suitable site to investigate the influence of pedogenetic processes on the fate of Cu. Samples were collected from all horizons along a trench at four distances from the drain: 0.6m, 1.1m, 2.1m and 4.0m. In the E&Bt horizon, four different soil volumes (ochre, pale brown, white-grey and black) were sampled at all four distances from the drain. Furthermore, we analyzed soil solutions sampled with piezometer, porous cups, and at the drain outlet. The Cu concentrations were lowest in the surface (Ap) horizons (6.5–8.5μgg −1) and increased with depth to the clay-rich Bt horizons (10.5–12μgg −1), because of clay eluviation and associated Cu transport. The δ 65Cu values significantly decreased from the surface (Ap=−0.25±0.07‰) to the deeper horizons, but showed no significant variation among the deeper horizons (−0.41±0.28‰) and no correlation with the clay content, indicating that clay eluviation did not significantly affect δ 65Cu values. The isotopically heavier δ 65Cu values in the Ap horizons can probably be explained by agricultural management practices like sludge application and fertilization. Close to the drain (position 0.6m), Cu concentrations were depleted and the lighter Cu isotope was enriched (−0.91±0.15‰) in the uppermost part of the E&Bt horizon. We attribute this to the changing redox conditions, caused by the lowering of the water level close to the drain. Copper concentrations in black and ochre volumes were significantly higher than in pale-brown and white-grey volumes. The black volume had significantly higher δ 65Cu values than the ochre volume indicating preferential sorption/occlusion of the heavy Cu isotope by Fe oxides. Enhanced clay eluviation in bulk soil close to the drain and in specific soil volumes did not affect δ 65Cu values. Cu concentrations (2.1–14μgL −1) and δ 65Cu (0.04–0.42‰) values in water samples showed no clear relation with redox changes along the trench perpendicular to the drain. The enrichment of the heavy Cu isotope in the solution samples (Δ 65Cu (soil-solution)=−0.61±0.41) indicates that reductive Cu mobilization is not the main driver of Cu leaching, because this would preferentially mobilize isotopically light Cu. We conclude that the eluviation of the <2μm fraction, strongly controlled Cu concentrations, but had no discernible effect on δ 65Cu values. The changing redox conditions did not seem to control Cu concentrations and the stable isotope distribution in most of the bulk soil, soil volumes and soil water. Instead, weathering, complexation of leached Cu, Cu application with fertilizers and sorption processes within the soil controlled its δ 65Cu values.
AB - Copper is a redox-sensitive trace element, which can be both, an essential micronutrient and a pollutant. We therefore analyzed Cu concentrations and stable isotope ratios (δ 65Cu values) in a drained Retisol to trace the response of Cu to a changing hydrological regime and enhanced clay eluviation. The study soil was artificially drained 16years before sampling resulting in macroscopically visible pedogenetic changes and is thus a suitable site to investigate the influence of pedogenetic processes on the fate of Cu. Samples were collected from all horizons along a trench at four distances from the drain: 0.6m, 1.1m, 2.1m and 4.0m. In the E&Bt horizon, four different soil volumes (ochre, pale brown, white-grey and black) were sampled at all four distances from the drain. Furthermore, we analyzed soil solutions sampled with piezometer, porous cups, and at the drain outlet. The Cu concentrations were lowest in the surface (Ap) horizons (6.5–8.5μgg −1) and increased with depth to the clay-rich Bt horizons (10.5–12μgg −1), because of clay eluviation and associated Cu transport. The δ 65Cu values significantly decreased from the surface (Ap=−0.25±0.07‰) to the deeper horizons, but showed no significant variation among the deeper horizons (−0.41±0.28‰) and no correlation with the clay content, indicating that clay eluviation did not significantly affect δ 65Cu values. The isotopically heavier δ 65Cu values in the Ap horizons can probably be explained by agricultural management practices like sludge application and fertilization. Close to the drain (position 0.6m), Cu concentrations were depleted and the lighter Cu isotope was enriched (−0.91±0.15‰) in the uppermost part of the E&Bt horizon. We attribute this to the changing redox conditions, caused by the lowering of the water level close to the drain. Copper concentrations in black and ochre volumes were significantly higher than in pale-brown and white-grey volumes. The black volume had significantly higher δ 65Cu values than the ochre volume indicating preferential sorption/occlusion of the heavy Cu isotope by Fe oxides. Enhanced clay eluviation in bulk soil close to the drain and in specific soil volumes did not affect δ 65Cu values. Cu concentrations (2.1–14μgL −1) and δ 65Cu (0.04–0.42‰) values in water samples showed no clear relation with redox changes along the trench perpendicular to the drain. The enrichment of the heavy Cu isotope in the solution samples (Δ 65Cu (soil-solution)=−0.61±0.41) indicates that reductive Cu mobilization is not the main driver of Cu leaching, because this would preferentially mobilize isotopically light Cu. We conclude that the eluviation of the <2μm fraction, strongly controlled Cu concentrations, but had no discernible effect on δ 65Cu values. The changing redox conditions did not seem to control Cu concentrations and the stable isotope distribution in most of the bulk soil, soil volumes and soil water. Instead, weathering, complexation of leached Cu, Cu application with fertilizers and sorption processes within the soil controlled its δ 65Cu values.
KW - Copper isotopes
KW - Drainage
KW - Lessivation
KW - Redox conditions
KW - Retisol
KW - Soil volumes
KW - Soil water
UR - http://www.scopus.com/inward/record.url?scp=85017555507&partnerID=8YFLogxK
U2 - 10.1016/j.geoderma.2017.04.003
DO - 10.1016/j.geoderma.2017.04.003
M3 - Article
VL - 300
SP - 44
EP - 54
JO - GEODERMA
JF - GEODERMA
SN - 0016-7061
ER -