Microcystins And Derivative Volatile Organic Surfocompound In Gonghu Bay, Lake Taihu

Mass growth of cyanobacteria (blue-green algae), leading to the production of blooms, accretion of pollutions occurs in eutrophic waterbodies of Gonghu Bay in Lake Taihu. The water source area planed for Wuxi city. Microcystins and derivative volatile organic surfocompound, the metabolites of harmful blue-green algae and decompound or secondary metabolites of algae, is primary pollutant. Microcystin is inducer of liver and intestinal cancer, which also could threat other aspects of human health through food chain or bioaccumulation such as liver cancer and intestinal cancer to the high incidence of birth deformities and volatile organic surfocompound derived from algae decompose pollutants cause deterioration of water quality water source, so that sensory deterioration of water quality. To protect the supply security from water sources, the paper subsidized by the national science and technology supporting project "The technical and demonstrative research of the cyanobacteria bloom subduction and water quality improvement at water intake in water sources area.", "The project of monitoring on cyanobacterial toxins and derivative volatile organic surfocompound in the water source".The area of cyanobacteria bloom subduction exemplars and water sources in Gonghu Bay in Lake Taihu was the Survey region, Based on ELISA, we built the fast and handy method to detect microcystins.and to monitor demonstration project in the region which was implemented the physical, biological algae control measures, both inside and outside the water column around barricading and provid technical support for emergency monitoring microcystins in water sources area. Based on luminous bacteria Vibrio qinghaiensis sp-Q67, we construct the acute toxicity diagnostic monitoring system on water quality in water sources area. Base on extraction and solid phase extraction method, we use HPLC to detect microcystions accumulated in ambient medium (eg. Substrate sludge and aquatic plant) in aquatic ecosystem. We study the MCs biotoxicity on the process of Hybrid rice seed germination and Bellamya purificata using the crude extract from cyanobacteria bloom. Through the simulation of the cyanobacteria decompose process, we construct SPME-GC/MS methods to detect the odor substances decomposed and to trace the release laws of derviative volatile organic sulfocompound from decayed cyanobacteria. The results are as follows:(1) Monitor the cyanobacteria blooms in Lake Taihu through application of satellite remote sensing data. There were cyanobacteria blooms occurring at Gonghu Bay since 2005, and it occurred more frequently after 2007. The water quality in Gonghu Bay had smooth fluctuations from 1987 to 2003 concluded from the historical data. The maximum TP was 0.1 mg-L-1 and total Nitrogen increased slowly. The pollution loading increased sharply in Gonghu Bay since 2005. The maximun total Phosphorus reached up to 0.25 mg·L-1 and NH3-N reached up to 1.42 mg·L-1. The maximum Chlorophyll a was 47.6μg·L-1. The Chlorophyll a in water blooms up to 703.04μg·L-1 and total Phosphorus reached up to 0.269 mg·L-1 in survey region in 2009.(2) The concentration range of MCs dissolved in water column of Gonghu Bay was between no detected and 0.554μg MC-LR eq·L-1 from Mar.2009 to Feb.2010. Dissolved MCs in all barricadings water column variated a higher concentration in March, April, July, August and December. The total MCs significantly increased after cyanobacterial bloom, downward trend in October. Around the barricading 5, dissolved MCs in water column more than dissolved MCs in other barricading, may be due to biological control measures of ecological stress effects of algae and floating plants, and the effect of increasing into a algae polymer, so as to cause release of microcystins. Various points around inside the total MCs in the water column after the outbreak of algal blooms increased significantly. In addition to the total MCs around barricading 1 than control barricading 5, barricading 2,3,4 were higher than the total MCs around the barricading 5. We conclude that Carps taken control cyanobacteria in barricading 1 works better than other biological measures.(3) Dissolved MCs of the waer column inside of barricading may be due to effects of ecological stress was higher than the same period, particularly around the water column dissolved MCs, hydrodynamic conditions is particularly good around September and October sampling points lower content of dissolved MCs, but the pollution risk is higher from external sources. In addition to the total MCs in the water column around a barricading, the barricading around the average concentration of total MCs especially around the water column above the total MCs, The barricading and floating plants around the hydrodynamic conditions weakened, creating an outbreak of cyanobacteria blooms in situ environmental conditions, so use around the physical control of cell blocks of exogenous cyanobacteria works cyanobacteria contamination is possible, but not to reduce the local water cyanobacteria, floating plants in the demonstration area of less effective control of cyanobacteria, Microcystins easy to promote aggregation, and possibly because Ecological effects of increasing stress dissolved MCs pollution.(4) Based on freshwater luminous bacteria Vibrio qinghaiensis sp Q67, we established a rapid diagnostic method of acute toxicity test. The Vibrio qinghaiensis sp Q67 acute toxicity best test conditions is determined as pH value of 5.0-9.0, the initial bacterial density of 0.1-0.2 million and the test time 20 - 30 min. The median effect concentration (EC50) of MC-LR on Vibrio qinghaiensis sp Q67 was 1.96 mg·L-1.(5) The acute toxic effects of Vibrio qinghaiensis sp Q67 is different from the toxic effect by heavy metals and organic pollutants when Vibrio qinghaiensis sp Q67 used to detected the toxicity of microcystin.Detecting the toxic water result in microcystin, the toxic effects not only appearing a slightly inhibitory action,but also stimulatory effect. The detect results of Vibrio qinghaiensis sp Q67 acute toxic effects in different sampling sites in the cyanobacteria subduction exemplars of Gonghu Bay are identical. Water acute toxic effects appearances stimulatory effect in Mar and April, slight inhibitory action in Aug and strong stimulatory effect in Sept and Oct. In different period of time, the correlation of average concentration of dissolved MCs and the mean acute toxic effects of Vibrio qinghaiensis sp Q67 is obvious in each sampling sites, and the correlation coefficient is 0.643. The acute toxic effects of Vibrio qinghaiensis sp Q67 is particular when detected by microcystin. When relative luminous efficiency of Q67 acute toxic effects is less than 80% or the stimulatory ratio is more than 120%, the non-toxic water transformed into toxic, which can be used as a reference for water acute toxic assessment.(6) Cyanobacteria blooms occurred in Gonghu Bay in Lake Taihu, Microcystis wesenbergii was primary algae in summer 2009. The maximum microcystins producted by cyanobacteria appear early in September (174.27μg MC-LR·g-1 DW and 162.69μg MC-RR·g-1 DW). microcystin accumulated in various organs of Zizania aquatica, Trapa quadrispinosa Roxb and Trapa bispinosa Osbeck, concentration in leaves of Zizania aquatic is highest (10.44μg MCs·g-1 DW), The amount of microcystin concentration in putkin of Trapa quadrispinosa Roxb are 1.97μg MC-LR·g-1DW and 0.69μg MC-RR·g-1 DW, higher than bioaccumulation in root of Trapa quadrispinosa Roxb. Bioaccumlation of microcystin was the same concentration in Bellamya purificata collected from Meiliang Bay in Lake Taihu 2005 and Lake Caohu 2006 (maximum concentration is 4.66μg·g-1DW). The maximum concentration of MC-LR in Silver carp intestine and liver was 7.22μg·g-1 DW and 7.63μg·g-1 DW, the maximum concentration of MC-RR was 5.51μg·g-1 DW and 3.75μg·g-1 DW. Bioaccumulation of MCs in muscle of silver carp collected in Gonghu Bay 2009 is 3.69μg·g-1DW and Bioaccumlation of MCs in muscle of silver carp collected from Meiliang Bay in 2006 is 1.65μg·g-1 DW. There was a little increase. The maximum microcystin accumulated in sediment collected from Ginghu Bay is 1.18μg MC-LR·g-1 DW and 0.72μg MC-RR·g-1DW. The detected samples were 12, but MC-LR was not detecte only in one sample.(7) Different concentrations of microcystins on seed germination in physiological indicators such as water absorption, germination rate, root activity TTC, chlorophyll content and chlorophyll a and chlorophyll b ratio of Hybrid Rice showed high concentrations of the inhibitory effect of microcystin more serious. Bellamya purificata is the role of microcystins accumulation significantly, the storage coefficient is 1.86. semi-lethal dose of MC-LR on Bellamya purificata is about 15.49-28.79μg·L-1. To analogize, the human MC-LR safety limit reference concentration maybe 0.025μg MC-LR eq·kg-1 BW (0.015-0.029μg MC-LR eq·kg-1 BW).(8) On the third or the fourth day of cyanobacterial decomposing, microcystins has the biggest release emission, the release emission of MC-LR and MC-RR is 60 and 64 times higher than the background value, respectively. The maximum concentration was 8.32μg MC-LR·L-1, 14.04μg MC-RR·L-1, converted into a algae toxin production capacity were 2.46μg MC-LR·g-1 FW and 4.31μg MC-RR·g-1FW.(9) In this study, a new method, (SPME-GC/MS) was built to detect the derivative volatile organic surfocompound. The primary or secondary metabolites by Cyanobacteria in the kinds of water samples, such asβ-cyclocitral, indol, methylphenol, mercaptan and thioether were detected with SCAN. With the analyzes of the components of the odour substances, which is the production of the putrefactive Cyanobacteria, we can proved that the polluted water in the Gonghu Bay in May,2007 is as a result of the bulk decayed Cyanobacteria.(10) The maximum emission of Dimethyl trisulfide in water samples of decaying blue-green algae was appeared on the first 7 days or 8 days, which is amounted to 383 times of the background value. The peaks of the Dimethyl trisulfide emission in the decaying algae samples was appeared on the third day or the ninth day during ten days; dimethyl disulfide released gently in rot water samples, and lasted a long time; The maximum emission of dimethyl sulfide was appeared on the eighth day or the ninth day in blue-green algae decompose water. In water source samples, the maximum detected concentration of Dimethyl trisulfide is 2344.79 ng·L-1.Based on these above-mentioned results, the water source of Gonghu Bay is suffering the cyanobacteria metabolites and sulfur derivatives the pollution threat, cyanobacterial blooms in the establishment of comprehensive early warning system and to take effective measures algae abatement project is to get water safety important safeguard. We established a rapid toxicity diagnostic technique for Vibrio qinghaiensis sp. Q67. The technique needs to be further improved; SPME-GC/MS accurately detect the release of algae decompose odor of sulfur derivative materials, but extracted from water samples of volatile organic sulfur recovery and reproducibility are low, yet continue to explore and select the sample preparation method for accurate quantitative analysis of the release law of the sulfur in the decaying cyanobacteria.