The Variation Characteristics Of Volatile Organic Compounds Of Northern Cyanobacterial-Enriched Region Of Dianchi Lake

Lake Eutrophication and cyanobacteria blooms have been aroused by public, and volatile organic compounds (VOCs) from air-water of Eutrophication Lake may bring water and regional environment adverse effects. For solution these problems, investigating VOCs emissions and affecting factors were prerequisite. But the informations about VOCs causing public safety and air odor problems had little data or reports. A typical eutrophic lake has been selected in this study, the samples from north cyanobacterial-enriched region were collected and analyzed by floating chamber method-absorption tube-preconcentration-GC/MS.According to the method, a kinds of VOCs had been identified and determined concentrations.Diurnal variation, month variation in sample days of environment concentrations, fluxes and the affected factors, such as Chl.a, Microcystis density, temperature had been investigated during January in 2008 ~ December in 2008. The VOCs from algae of eutrophic water has been discussed and the environmental pollution and ecological effects has been considered in this paper. The results showed that:(1) The emissions of VOCs from air-water interface include alkanes (methylene chloride,n-octane,n-dodecane),alkenes(2-methyl-1,3-butadiene,1R-alpha-pinene,limonene), aromatic compounds(benzene , toluene ,styrene),organic sulfur compounds ( dimethyl sulfide, dimethyl disulfide, oxygenated organic compounds (furan , 2-methyl-furan) in Algae rich region north of DianChi Lake, the largest ratio of the material for the aromatic compounds (28%~76%), and the smallest percentage of sulfur compounds (0.07%~40%)。 (2) The environment concentrations of VOCs have a significant diurnal variation and seasonal variation in the 5 sampling time in sample day (5:00,10:00,14:00,18:00,22: 00), the the maximum concentration(diurnal summit value) has been observed at 18:00 and the high value has appeared in July, September, October, November in sample days.(3) The fluxes of VOCs from cyanobacterial-enriched region in north of Dianchi Lake have a significant diurnal variation and seasonal variation.In general the absorption much lower than the emission flux that had been usually appeared higher value at night than during the day.Some higher fluxes value had been observed in March, July, September, November in sample days.(4) The concentrations and fluxes of VOCs from study region had been affected by many environmental factors, however the level of Chl.a was the major factors.The concentrations had obvious higher in crucial period of phytoplankton decline. In addition, rain had affected to reduce the concentrations and fluxes of VOCs.(5) The emissions of VOCs from north of Dianchi Lake has some environmental effects,calculating the value of cancer risk(CR) with some VOCs,the CR value shows that, the study region CR value is higher then the EPA standards.The results not only revealed the eutrophic water as a source of VOCs and provide a basis for hazard warning system for data, but also to fully understand the sources of atmospheric VOCs and revealed eutrophic water of organic pollutants on regional air quality, for reducing VOCs emissions in water to provide the scientific data.