Toxicity And Ecological Safety Evaluation Of Urban River Sediment Organic Extracts

Large amounts of toxic organic pollutants have been discharged into waterbodies with industrialization, causing potential harm to water sources, the pollution ofwater sources therefore has become one of the primary risk factors to public health.Many organic pollutants will eventually gather into the sediments after entering thewater body, which may cause direct harm to the organisms there. Meanwhile theorganic pollutants in the sediments can be released back into the water phase viaresolving process, diffusion, distribution, and then have an impact on the entire waterecosystem. So the pollutant status of the sediments has become an important index forevaluation of water quality. In recent years, it has become an important means ofevaluating the water environmental quality to use the sediments to evaluate waterenvironment pollution. The main objective of this paper is to use a variety of in vitrotoxicity testing methods to evaluate the toxicity of toxic organic pollutants in thesediments in water sources and the ecological security. The main research contentsand results are as follows:（1）Development of the marker methods of in vitro biological effect, including thecultivation of cells and engineering bacteria, the determination of test indexes and theprocess of biological toxicity testing. The effect tests of organic extracts in sedimentsfrom Taihu Lake, Huangpu River and its tributary Suzhou River had been done withthe method. Including: the toxicity tests of cell survival rate and changing level ofintracellular ROS using in vitro cultured cells; the genetic toxicity tests usingumu/SOS and comet assay; the evaluation of endocrine disrupting effects usingrecombinant hormone receptor gene in yeast two hybrid; the evaluation of arylhydrocarbon receptor (AhR) effect using inductive effect of EROD in rat hepatomacells (H4IIE).（2）The results of cytotoxicity test indicated that, under the existing experimentalconditions, the organic extracts from sediments of Taihu Lake showed no toxic effecton cells, but some samples from Huangpu River and its tributary Suzhou River showed certain cytotoxicity to test cells and had different influence on the change ofintracellular ROS levels; Comet assay and umu/SOS experimental results suggestedthat a fraction of sediments samples from the Taihu Lake, Huangpu River and SuzhouRiver showed certain genetic toxicity.（3）Detection of endocrine disrupting effect of sediment organic extracts includingestrogen effect and thyroid hormone effect, estrogen and thyroid hormone effectswere expressed by the equivalent concentration of estradiol (E2, EEQ) and thyroidstimulating hormone (T3, T3-EQ) respectively, the samples of Huangpu River and itstributaries Suzhou Creek were only tested the effect of estrogen. The results showedthat the equivalent concentrations of estrogen effect (EEQ) in Taihu Lake was0.001112.38pg/g, with a mean of1.57pg/g, thyroid hormone (T3-EQ) equivalentconcentration was0.35to0.35pg/g, with a mean of7.74pg/g, the estrogen andthyroid hormone effects were in medium or low levels compared with other domesticand foreign research area; the estrogenic effect equivalent concentration EEQ inHuangpu River and Suzhou Creek was42.34-983.52pg/g, which was higher than theestrogenic effects of organic extracts from Taihu Lake sediments.（4）Aryl hydrocarbon receptor effect of sediment organic extracts was expressedby2,3,7,8-TCDD equivalent concentration (TEQbio). The test results showed that theTEQ range of sediment organic extracts in Taihu Lake was2.70-37.8pg/g, with amean of14.2pg/g; the TEQ range of sediment organic extracts in Huangpu River andSuzhou River was7.37-73.44pg/g, the EROD effects in Taihu Lake and HuangpuRiver were in medium or low level compared with other research areas. In order todefine the contribution of polycyclic aromatic hydrocarbons (PAHs), which hadstrong aromatic receptor effect, to the sediment organic extracts EROD effect, wecalculated the contribution rate of PAHs to EROD effect obtained by biological testsaccording to the results of chemical analysis. The average contribution rate of PAHsto EROD effect was48.9%in the whole lake aera; The average contribution rate ofPAHs to EROD effect was64%in Huangpu River and its tributaries Suzhou Creek,which indicated that the PAHs had an important contribution to the EROD effect inthe both regions. the preliminary environmental risk assessment results showed that the PAHs had low ecological risk to aquatic organisms, but the compounds withEROD effect in the sediments had a certain risk to sensitive organisms and theirpredators, which should cause the attention of the relevant environmentalmanagement department.The organic toxicants from the river were selected through a variety of toxicitytests in vitro, and then the typically toxic organic pollutants were confirmed. All thesework as well as the environmental risk assessment had vital practical significance onsetting regional water environmental management objectives. The research resultssuggested the risk compounds that should be taken more attention and the potentialecological safety. Avoided The blindness and uncertainty of environmental riskmanagement that soly relied on a single method before was getted rid of, and it madethe environmental management targeted and was also conducive to set the appropriateenvironment remediation goals, and thus the unnecessary economic waste wasavoided.