The Toxicologicaleffects Of Low Concentration Of Glyphosate And Its Roundup(?) Formulation In Aquatic Environment On Carassius Auratus

Glyphosate is a non-selective, broad spectrum, post-emergent organophosphate herbicide. Roundup(?) is the most common formulation, containing isopropylamine salt of glyphosate (G.I.S) as the active ingredient and polyoxyethylene amine (POEA) as the surfactant agent. With the development of transgenic glyphosate-resistant crops, the usage amount of glyphosate increases every year, and accompanied by a large number of glyphosate formulations entering the environment through a variety of ways. It seriously affected the water quality and functions of the aquatic ecosystem, and even did harm to the aquatic organism and human beings. In order to reveal the presence of glyphosate in aquatic environment and the toxicity of glyphosate on the aquatic organism, this study established ion chromatography procedureto detect glyphosate in water environment,s well as compared the toxicological effects of glyphosate and Roundup(?)、G.I.S and POEA on fish Carassius auratu. The major results are as follows:1. Fish were exposed to a wide range of concentrations (0.032,0.16,0.8,4.0mg/L, all calculated on glyphosate basis, similarly hereinafter) of glyphosate and Roundup(?) for11days, respectively. There was no accumulation of·OH when exposed to glyphosate. While·OH was significantly induced from0.032mg/L to4.0mg/L of Roundup(?). The activity of superoxide dismutase (SOD) was significantly inhibited at the similar level from0.032mg/L to4.0mg/L of Roundup(?), while gradually inhibited with an elevated level of glyphosate, suggesting that the Roundup■formulation was more toxic than glyphosate itself. No obvious difference in the activity of catalase (CAT) exposed to Roundup(?) group and glyphosate group could be observed.2. Fish were exposed to0.16,0.032and0.0064mg/L of Roundup(?)(containing41%isopropylamine salt of glyphosate (G.I.S) and18%polyoxyethylene amine (POEA)), G.I.S, and POEA for7days. Hydroxyl radical (·OH) could be induced by exposing Roundup(?) at a rate of43%-111%, G.I.S at90%-124%and POEA at142%-157%. The contents of MDA significantly increased when exposed to all set concentrations of Roundup(?),0.16mg/L G.I.S and0.032mg/L POEA. The exposure led to an inhibition of acetylcholinesterase (AChE) in livers overall during the experimental periods. The inhibition percentages range from28%-40%in Roundup(?),5%-23%in G.I.S, and20%-50%in POEA, suggestingthe toxicity order of the chemicals was:POEA>Roundup(?)>G.I.S.3. Fish were exposed to0.032mg/L Roundup(?), G.I.S and POEA over different periods (0.5,1,3,7and14d). Results showed that the generation of-OH increased before7d, but without significantly difference.·OH was induced at1d for POEA group,3d for Roundup(?) group and7d for G.I.S group. At14d,·OH generation returned to normal levels. MDA contents increased significantly (p<0.01) during7days and then reached a normal level at14d. AChE activity in all groups were inhibited significantly (p<0.01) after7days exposure and then rebounded a little,. The percentages of AChE inhibition range from13%-42%in Roundup(?),6%-40%in G.I.S, and21%-54%in POEA, suggesting that POEA was more toxic compared to Roundup(?) and G.I.S.0.032mg/L Roundup(?) exposure led to the change of physiological and biochemical indexes in C. auratus, which was a reversible process in the long run.4. Compared to the method of ion chromatography with conductivity detector, capillary ion chromatography method for glyphosate provide lower detection limit, small interference by other factors and high resolution and effciency. The determination of glyphosate from April to June of2011in Taihu Lake used ion chromatography with conductivity detector, showed the content of glyphosate in June was higher than other months. Higher glyphosate concentrations were detected in north Lake Taihu.