Ecological Damage Assessment Of The Thermal Discharge From The Power Plant In Xiangshan Bay And Its Compensation

The number of an annual increase of installed capacity and the thermal dischargewater into the natural waters in China’s power plant constructionis highest of in theworld,the cooling water discharged will makefrom various large-scale nuclear powerplant or power plant group directlycauses the environmental change of receiving seaarea,this pollution arouses great public concern.After analyzing the data of water nearby the power plant during2005to2008,itfound that:1)The rising of temperature changeis distinct in monitored area, with50.75%of the area in monitored areathe temperature rising exceed0.8℃.2)The resultof analysis of water shown that pH,COD and Asmet National GradeII, but thenutrient,such as N and P,is far beyond the standard. The result of analysis of biologicalindicators shown that species in each biological group was decline sharply, species ofphytoplankton was dropped from71in2005to39in2008and species of zooplanktonwas dropped from51in2005to22in2008,the predominant species of benthos waschange clearly, which changed from the mollusk to polychete. Correlation analysisindicated that the biological indicators is high negative correlation with the temperaturerising except phytoplankton’s biomass, the relationship between the biomass ofphytoplankton and temperature rising is complex, it need a further research.Studies on phytoplankton damage in cooling water of a power p lant revealed areduction in biomass when the temperature rise0.8℃, which validated the monitoringresults that the phytoplankton dropped rapidly drop rapidly after the power plant wasput into operation. The experimental results show that if the cooling water maketemperature rise exceed0.8℃, it will cause at least45%of damage, and if the coolingwater make temperature rise less than0.4℃, there is a little influence, it may be goodfor the growth of the phytoplankton in some condition. Correlation analysis between thephytoplankton and environmental factors shown that chlorophyll a and nutrients werenegative correlation， it is difference in correlation with COD, DO which reflects indirectly the impact of the exotherm on phytoplankton, these indicators can be used asauxiliary indicators in the damage assessment of the thermal discharge forphytoplankton.Based on B-P ANN, a model of ecological damage assessment of thermaldischarged water was presented. According to analysis results of monitoring data during2005to2008and quantitative conclusionfrom enclosure experiment.The metricsinclude DIN, PO₄-P, COD, chlorophyll a and temperature rising，including5orders ofevaluation. The evaluation results show that Damage rating of waters nearby the outfallof Guohua power plant is-2, which is most severe. Evaluation results aslo show that thedischarge water is favorable its biological growth in Tie Harbor and Huangdun Harbor.The damage level of is2in waters near the estuary of Shimen River in Dajiahe Town,whici is the most conducive to biological growth, Speculated that if when therr aresufficient nutrients and suitable temperature, the area wiil at risk of outbreak of redtide.This article learn from results of habitat equivalency analysis （HEA） that had beenstudied by Richard W.Dundord （2004）, Steven M. Thur （2007） and reference todomestic and foreign scholars on casesthe HEA analysis.Affectting the actualtemperature and drainage of habitats, this article makes the HEA model appropriateimprovements.The model improved can effectively assess the size and value ofecological compensation for Guohua Power Plant. For example,the compensationhabitat area is about33.03km2calculated by the HEA model improved, accounting forabout27.24%of the overall impacted habitat, the value of the compensation habitat isabout610million.The sensitivity analysis of HEA improved lossesfor the thermaldischarge water changes in its input parameters shown that the HEA loss estimates inour example are most sensitive to “number of injured acres”,the sensitivity analysis ofHEA gain estimates to the associated input parameters shows that “year service gainsend” have a substantial effect on the HEA gain estimates in our example.Therefore, howto determine the value of these two parameters is the key to the results of evaluations.The parameter of “number of injured acres” in our example was taken from results ofthe local scene mesocosm experiment and historical monitoring data, which can accurately reflect the damage of thermal discharge water. Therefore, the evaluationresults in this case are valuable for its ecological compensation.