The influence of aging on the comparative terrestrial ecotoxicity potential of copper and zinc in soils

Metal exposure to terrestrial organism is influenced by the reactivity of the solid-phase metal pool. Aging is one of the important factors that control the reactivity of the solid-phase metal pool in soil. In this study, the selected 13 soils were collected from different locations of China, representing different soil types. The reactivity variation of spiked Cu and Zn with aging was assessed in these 13 soils, and their comparative toxicity potentials (CTPs) were also calculated. The median reactive fractions (freactive) of Cu and Zn with 95% confidence intervals were 1.6 × 10−2 (3.5 × 10−6 to 2.2 × 10−1) and 0.10 (9.1 × 10−4 to 0.44) kgreactive/kgtotal, and the median CTPs for Cu and Zn were 2.09 (8.1 × 10−4 to 2.2 × 104) and 0.85 (8.5 × 10−4 to 7.2 × 102) m3/kg day, respectively. The statistical analysis indicated that aging variability in the CTP of Cu and Zn was mainly associated with the variability in soil organic carbon and pH. These results stress the importance of dealing with aging in the calculation of CTPs for terrestrial ecotoxicity of metals.