Combined pollution of agrichemicals and heavy metals were commonly observed worldwide and growth concern about the issue led the administrations like EPA and European Union to require the consideration of mixture effects in environmental risk assessment. However, little has been reported on the ecological risk of combined pollution, especially in field due to lack of systematic methodology in assessing joint ecological effects and mechanistical data. In this study, mixture effects of herbicide siduron and heavy metals on mortality, DNA damage, gene expressions of metallothionein and heat shock protein70 in earthworm (Eisenia fetida) and cucumber root elongation were investigated and calculated based on single toxicology data of siduron and heavy metals using independent action and concentration addition model. Environmental behaviors of siduron in heavy metal contaminated soils were investigated with batch experiments in four soils (C, N1, N2, N3) from two public parks in Beijing, China, with similar properties but contrasting heavy metal contaminated level. Based on that the environmental exposure level of siduron was simulated with HYDRUS-1D model. Results suggested that soil organic matter rather than the co-existed heavy metals was the dominant factor affecting the fate and accumulation of siduron in soils. Then the predicted no effect concentration (PNECsoil) of siduron was calculated with equilibrium partitioning method and extrapolation techniques. The PNECsoil of siduron derived from both root elongation and earthworm mortality was the lowest in the heaviest heavy metal contaminated soil N3 . The risk characterization ratios (RCR) of siduron in four soils were all greater than 1. The highest RCR of siduron in soil N3 suggested that it was the joint toxicity of siduron and heavy metals to organisms determining the ecological risks of siduron in combined polluted soils.

Ecological risk evaluation of combined pollution of herbicide siduron and heavy metals in soils

256th National Meeting (2018)

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