Contamination Identification And Risk Assessment Of Atrazine In Typical Agricultural Region

Atrazine is one of the triazine herbicides. It is widely used to control grassy and broadleaf weeds in corn, sorghum and other plants. One of the main environmental problems about the use of atrazine is its persistence. This herbicide is considered as an endocrine disrupting chemical. Even worse, dealkylation products of atrazine, atrazine-desethyl (DEA) and Atrazine-deisopropyl (DIA), appear similar toxicity to the parent herbicide. The hydrolysis of ATZ metabolites (OHA) may lead to kidney stones and nephritis. The ecological risk of atrazine brought more and more attention.In this study, we established some methods with the combination of QuEChERS, SPE, HPLC and HPLC-MS/MS for the analysis of atrazine and its metabolites. Firstly, the degradation processes of ATZ in five soils were studied, and then compared with the degradation activity of ATZ in different soils according to the first order kinetics. Secondly, we analyzed the residual concentrations of ATZ and its metabolites in water, soil and sediment samples in typical agricultural region. In addition, we analyzed the relationship of ATZ and its metabolites between time, space and muti-media in the environment. Finally, the toxicity data of ATZ were collected to assess the ecological risk of ATZ and its chlorinated metabolites in the typical agricultural rigion by hazard quotient method.The results showed that the degradation rate constant of k of atrazine in unsterilized soils: farmland A2(0.404 d-1)>kfarmlandA1(0.339 d-1)>kriver(0.282 d-1)>kpond(0.274 d-1)>kchannel(0.107 d-1); k of atrazine in sterilized soils:kriver(0.358 d-1)>kpond(0.188 d-1)>>kfarmland A2(0.048 d-1)? kchannel(0.047 d-1)?kfarmland A1(0.041 d-1). The soil degradation ability of farmland, river and pond is stronger as compared to the channel soil. And its major metabolite is OHA.After one week of using atrazine, the residual concentration of ATZ and its metabolites reached to 1.890 ?g/L in the river, and 1.174 ?g/L in the reservoir, respectively. After four months, the TTR of Shehe, Suzihe, Hunhe and the reservoir was 9.36%,23.4%,18.1% and 56.5% of the first period, respectively. The results showed that ATZ and its metabolites could decrease more quickly in the river than the reservoir, while accumulation occurred in the reservoir. We established the migration equilibrium equation of ATZ to analyze the composition of pollutants in water, soil, and sediment samples. Another equation was used to analyze the composition of pollutants in reservoir and three estuaries of reservoir. Therefore, the main sources of the pollutants can be estimated and we could screen out high residue sampling points and analyze the reasons.Hazard quotients of TTR were used to assess the environmental ecological risks of atrazine and its metabolites. The results showed that atrazine and chlorinated metabolites produced great ecological risks in the entire period; and it had no effect on toad. Through the ecological risk assessment of atrazine and its chlorinated metabolites, we selected the sampling points where there were high ecological risks, and then combined with the analysis of pollution source and degradation experiments, we could give some suggestions to decrease the ecological risk. For instance, the farmers could cut off the conmatination from the farmland and repair the pollution of sediment.