Tracing concentrations and isotope ratios of zinc along an agricultural gradient.

摘要

Zinc (Zn) is a common additive in agricultural fertilizers, because it is essential to biological function. These inputs may adversely increase total Zn and affect isotope ratios in surrounding environments and organisms. We used high precision Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) to quantify Zn concentrations and isotope ratios in an indicator species, freshwater mussel (Family: Unionidae), and soil taken from 14 streams selected to have a range of agricultural land use in Southern Ontario. We found that Zn concentration and isotope ratios in mussels varied between sites, but were not strongly related to agriculture, as assessed using GIS land cover data. delta66Zn values in mussels were more depleted compared to other materials cited in the literature, and mussels had ratios of delta66Zn to delta68Zn that were not consistent with natural Zn abundance. We also found a relationship between delta68Zn and total body phosphorus in the mussels. This study has furthered our knowledge of Zn isotope ratios in freshwater mussels and explored applications to land cover assessment.;Keywords: zinc, stable isotopes, agriculture, trace metals, mussels, nutrients, water, streams.