Tracing contamination sources in soils with Cu and Zn isotopic ratios

Abstract

Copper (Cu) and zinc (Zn) are naturally present and ubiquitous in soils and are important micronutrients. Human activities contribute to the input of these metals to soils in different chemical forms, which can sometimes reach a toxic level for soil organisms and plants. Isotopic signatures could be used to trace sources of anthropogenic Cu and Zn pollution. The aim of this paper is to determine whether it is possible to identify (i) Cu and Zn contamination in soils and their sources, on the basis of their isotopic signatures, and (ii) situations that are a priori favorable or not for tracing Cu and Zn pollution using the isotopic approach. Therefore, we compiled data from the literature on Cu and Zn isotopes in soils, rocks and pollutants and added to this database the results of our own research. As only a few studies have dealt with agricultural contamination, we also studied a soil toposequence from Brittany, France, that experienced spreading of pig slurry for tens of years. In the surface horizons of the natural soils, the δ(65)Cu values vary from -0.15 to 0.44‰ and the δ(66)Zn from -0.03 to 0.43‰. Furthermore, vertical variations along soil profiles range from -0.95 to 0.44‰ for δ(65)Cu and from -0.53 to 0.64‰ for δ(66)Zn values. We concluded that pedogenetic processes can produce isotopic fractionation, yet, it is not always discernible and can be overprinted by an exogenous isotopic signature. Furthermore, some contaminants are enriched in heavy Cu or in light Zn compared to the rock or soil, but no generalization can be made. The anthropogenic inputs can be identified based on stable Cu and Zn isotope ratios if the isotope ratios of the sources are different from those of the soil, which needs to be tested for each individual case.

Ion Exchange Chromatography and Mass Bias Correction for Accurate and Precise Zn Isotope Ratio Measurements in Environmental Reference Materials by MC-ICP-MS

“…41 The δ 66/64 Zn JMC value for the 2709 San Joaquin soil is 0.28 ± 0.09‰ which is close to the δ 66/64 Zn JMC of 0.2‰ suggested for unpolluted soils. 44 The δ 66/64 Zn JMC values of 0.79 ± 0.09‰ (2σ, n = 8) for 1573a tomato are within the large range found in the plant leaves ranging from -0.91 to 0.63‰ for herbaceous species and 0.98 ± 0.19‰, 2σ for bamboo leaves. 7,45 The several factors of fractionation such as diffusive processes in cross-cell membrane transport, Zn bioavailable speciation and rhizosphere reactions 46,47 probably are associated to this heavy isotopic compositions of 1573a tomato leaves compared with soils and sediments.…”

The influence of weathering and soil organic matter on Zn isotopes in soils

“…There is no local contamination from industry or urban areas in the vicinity of our site, indicating that Zn isotope fractionation in these soils is unlikely to be associated with polluted Zn sources Cloquet et al, 2006Cloquet et al, , 2008Juillot et al, 2011;Sivry et al, 2008;Chen et al, 2008Chen et al, , 2009Bigalke et al, 2010;Fekiacova et al, 2015). Atmospheric dust input on Icelandic soils is dominated by volcanic material mainly basaltic from volcanic ash deposition during eruption or resuspended volcanic material (Sigfusson et al, 2008;Wittmann et al, 2017).…”

PM2.5 particulates and metallic elements (Ni, Cu, Zn, Cd and Pb) study in a mixed area of summer season in Shalu, Taiwan

“…Long-term exposure to copper can cause irritation of the nose, mouth and eyes, and it causes headaches, stomachaches, dizziness, vomiting and diarrhea (WTS (Cu) 2015). Copper (Cu) and zinc (Zn) are naturally present and ubiquitous in soils and are important micronutrients (Fekiacova et al 2015). Ingesting high levels of zinc for several months may cause anemia, damage the pancreas and decrease levels of high-density lipoprotein (HDL) cholesterol (Terry et al 2004).…”