[Spatial distribution and risk assessment of atrazine in Taizi River basin, China].

Atrazine (AT) has been detected in surface water and groundwater in many countries and regions around the world. Concentrations of AT in surface water, suspended particulate matter (SPM) and groundwater samples collected from the Taizi River basin, in northeast China, were analyzed using a gas chromatograph-mass spectrometer (GC-MS) in order to clarify their spatial distribution and environmental behavior, and to assess their potential ecological risk. Concentrations of AT varied from 0-734.0 ng x L(-1) for surface water, 0-1 493.6 ng x g(-1) for SPM and 30.0-245.0 ng x L(-1) for groundwater, with averages of 335.3 ng x L(-1), 382.9 ng x L(-1), and 104.4 ng x L(-1), respectively. The logarithm in situ SPM-water partition coefficients (lg k(oc)) of AT were in the range of 3.50-4.14 indicating that adsorption of AT from the aqueous phase to SPM plays an important role in dissipating AT in surface water. Fluxes of AT in surface water ranged from 1.5-184.7 mg x s(-1) in the basin, calculated based on the measured flow velocity and concentrations in surface water and SPM. The maximum value of AT flux was found in the middle stream of the Taizi River (S7). The risk assessment suggested that the ecological risk of AT in surface water was low, with more than 95% of the species protected from risk in the Taizi River basin. However, the residue levels of AT in surface water of the Taizi River basin may cause potential environmental risks.

Assessment of the genotoxicity of endosulfan in earthworm and white clover plants using the comet assay.

Endosulfan, as one of the most widely used organochlorine pesticides in the world, has increased the public concern about genotoxicity in soil ecosystems. The comet assay has been widely used in the fields of genetic toxicology and environmental biomonitoring. In the present study we conducted comet assay of endosulfan in earthworm (Eisenia foetida) and white clover (Trifolium repens L.), which are sensitive organisms suitable for acting as a bioindicator for agricultural ecosystems. Earthworms were exposed to endosulfan concentrations of 0.1, 1.0, and 10.0 mg/kg in the soil. White clover roots were immersed in hydroponic pots containing nutrient solutions of different endosulfan concentrations: 0.1, 1.0, and 10.0 mg/L. Tissues from each treatment were collected on the 7th, 14th, 21st, and 28th days of treatment process. Significant effects (p < 0.01) of both concentrations and times of exposure were observed. And endosulfan induced DNA damage in earthworm and white clover nuclei. The comet assay can be used as a reliable tool for early detection of endosulfan.