Analytical Method Of Total Microcystins And Their Pollution Characteristics In Dianchi Lake

Toxic blue-green algae bloom is a worldwide environmental problem. As the the frequency and intensity of the outbreak of the blue-green algae blooms increasing, it has formed the serioue consequences of water quality disaster. Therefore, governments and research institutions strengthen the management and research continuously. Microcystins are the metabolites of toxic cyanobacteria blooms, and it can strongly promote the secretion of carcinoma and liver toxicity, posing a serious hazard to human health and the environment security. Therefore, to solve the problem of research microcystins pollution characteristics, it’s very important to establish and improve an accurate and sensitive method to analysis the microcystins in environment medium. Taking the oxide of every isomer of microcystins as the research object, we established an analysis method to determination the total microcystins in environmental water samples by solid phase extraction, derivatization-gas chromatography/mass spectrometry. And studied the pollution characteristics and tending towards of microcystins in surface water quality monitored section of dianchi lake by this method.Using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)/Trimethyl chloro silane (TMCS)(1000:2, v/v) as the reagent of silanization, at room temperature for40min carboxyl of MMPB as the oxide of MCs can be completely derivatization, and the derived products are very stable. In the linear range of0.01to10ng-L"’, the linear of the standard curve of the derivative products of target material MMPB is good (r2is greater than0.996). When preprocessing the environmental water samples, regulating water pH to4.5or so, SepPak C-18solid-phase cartridges were used,15%methanol solution were used as leaching solvent and100%methanol (containing0.1%trifluoroacetic acid) were used as the elution solvent. Good recoveries of target compounds were obtained, the recoveries of were88.3%-100.4%. Reasonable repeatability and reproducibility of the established method were achieved with relative standard deviations (RSD) between1.3～4.1%for the target chemical in spiked water. The detection limits for the MCs in water samples were0.05μg/L, can meet the requirements of trace analysis of MCs in water sample.The water samples of ten national surface water quality monitoring section from Dianchi Lake were analyzedin order to study the pollution characteristics of total MCs in Dianchi Lake, and further to investigate their environmental fate. The results show that the concentrations of the total MCs in water in Caohai and Duanqiao section in January were640.34ng/L and450.37ng/L, the average concentration were545.36ng/L; While in march were298.55ng/L and213.74ng/L, and the average concentration were256.15ng/L. In January and march, the concentrations of the total MCs in Waihai section of Dianchi lake were450.37～1547.59ng/L (mean:1024.26ng/L) and1024.26-996.35ng/L (mean:629.77ng/L), respectively. The average concentration of the total MCs in January were higher than those in March. The average concentration of the total MCs in Waihai section is1.88times of that in Caohai section in January, and2.46times in March. The microcystins turn into the water after the bursting of algal cells, and migrate as the flow of water in Dianchi lake. They easily accumulate in by bioconcentration and biomagnification, and finally make the water in Dianchi lake and organisms exposed to microcystins widespreadly.