INFLUENCE OF RESIDUE CONCENTRATIONS OF BUTACHLOR-BASED HERBICIDE FACTOR ON DONG-SHENG WETLAND RIVULET FRESH-WATER PLANKTONIC ALGAE COMMUNITIES

摘要

The widespread use of herbicides in agriculture has resulted in butachlor residues in surface waters excavated from agricultural land, while surface waters are collected in streams and into wetland waters and may affect the primitive phytoplankton community in these natural ecosystems. With regards to study the exposure of freshwater phytoplankton community collecting experimental samples in the arable land (in 96h) to gradient concentration of butachlor (0.001, 0.005, 0.010, 0.050, 0.100, 0.500 and 1.000 mg L~(-1)) factor of compounded butachlor herbicide. The experimental results show that within the lowest concentration of 1.0mg L~(-1), it can reduce the content of chlorophyll a and carotenoids. When the concentration of Butachlor is as low as 0.005 and 0.010 mg L~(-1), it will accelerate the change of community configuration and reduce the consisting mainly composed of diversity algae species. When the concentration of butachlor ranged from 0.050 to 1.000 mg L~(-1), the population of phytoplankton community was significantly adjusted, and some indigenous species disappeared bizarrely, and some new planktonic algae species appeared at the same time. When the concentration of butachlor is as high as (0.500 and 1.000 mg L~(-1)), it will affect the concentration of shikimic acid secreted in the metabolism of planktonic algae, which will affect lipid peroxidation and antioxidant enzymes (such as ascorbate peroxidase, the super activity of oxide dismutase and catalase). The experimental results show that the introduction of butachlor herbicide into natural water body can significantly change the structural characteristics of freshwater phytoplankton community in the wetland of agricultural land drainage. However, the results show that the concentration of butachlor herbicide in wetland stream is much lower than that the 0.7 mg L~(-1) threshold specified in the Chinese-II Water Sanitation Standard.