TY - JOUR

T1 - Stable copper isotopes

T2 - A novel tool to trace copper behavior in hydromorphic soils

AU - Bigalke, Moritz

AU - Weyer, Stefan

AU - Wilcke, Wolfgang

PY - 2010/1

Y1 - 2010/1

N2 - Copper is an essential micronutrient for all organisms but may also be a pollutant. We studied the natural abundance of stable Cu isotope ratios in four soils to test whether δ65Cu values can be used as a tracer for biogeochemical processes in hydromorphic soils. Two of the soils were affected by stagnant water and the other two by groundwater. We determined standard soil properties and Cu partitioning into seven fractions of a sequential extraction. Copper stable isotope ratios were measured in total soil digests with multicollector inductively coupled plasma mass spectrometry. Copper concentrations in the study soils were low to average (5-34 mg kg-1). The variation in Cu isotope ratios was up to 0.6%0 in an individual soil. The organic layers of two of the profiles had lighter δ 65Cu values than the mineral soil, indicating isotopic fractionation of Cu during soil-plant-soil transfer. In the mineral soil, Cu isotopes showed distinguishable variations of up to 0.45%0. Thevertical distribution of the δ65Cu values, which paralleled that of the poorly crystalline to crystalline Fe oxide ratios, offers the first hints that Cu isotope ratios in soils may be influenced by alternating redox conditions. We conclude that variations in δ65Cu in soils are large enough to be distinguished and may be indicative of biogeochemical cycling and geochemical processes. In particular, Cu isotope ratios might be helpful to trace long-term processes such as element transport and redox conditions, which are difficult to assess otherwise.

AB - Copper is an essential micronutrient for all organisms but may also be a pollutant. We studied the natural abundance of stable Cu isotope ratios in four soils to test whether δ65Cu values can be used as a tracer for biogeochemical processes in hydromorphic soils. Two of the soils were affected by stagnant water and the other two by groundwater. We determined standard soil properties and Cu partitioning into seven fractions of a sequential extraction. Copper stable isotope ratios were measured in total soil digests with multicollector inductively coupled plasma mass spectrometry. Copper concentrations in the study soils were low to average (5-34 mg kg-1). The variation in Cu isotope ratios was up to 0.6%0 in an individual soil. The organic layers of two of the profiles had lighter δ 65Cu values than the mineral soil, indicating isotopic fractionation of Cu during soil-plant-soil transfer. In the mineral soil, Cu isotopes showed distinguishable variations of up to 0.45%0. Thevertical distribution of the δ65Cu values, which paralleled that of the poorly crystalline to crystalline Fe oxide ratios, offers the first hints that Cu isotope ratios in soils may be influenced by alternating redox conditions. We conclude that variations in δ65Cu in soils are large enough to be distinguished and may be indicative of biogeochemical cycling and geochemical processes. In particular, Cu isotope ratios might be helpful to trace long-term processes such as element transport and redox conditions, which are difficult to assess otherwise.

KW - BCR, basalt of the columbia river

KW - BS, base saturation

KW - CRM, certified reference material

KW - ECEC, effective cation exchange capacity

KW - ETAAS, electrothermal atomic absorption spectrometry

KW - GSP, granodiorite silver plume

UR - http://www.scopus.com/inward/record.url?scp=73849130397&partnerID=8YFLogxK

U2 - 10.2136/sssaj2008.0377

DO - 10.2136/sssaj2008.0377

M3 - Article

AN - SCOPUS:73849130397

VL - 74

SP - 60

EP - 73

JO - Soil Science Society of America Journal

JF - Soil Science Society of America Journal

SN - 0361-5995

IS - 1

ER -