Studies On Theories And Methods Of Estuary Ecosystem Health And Water Environment Risk Assessment

Healthy Ecosystem is the objective of environmental and ecological management, while ecosystem health assessment and risk assessment is an important support base of the construction of ecological security. Based on the international advanced ecosystem management concepts and methods, through the estuary ecosystems, hydrology, water quality, sediment quality, plankton and benthic organisms, and other characteristics of the estuary and the health status of the research and application of uncertainty analysis theory, this paper studied environmental risks, quantitative calculation of risk management and decision-making and other issues, and have made innovative achievements at estuary ecosystem health assessment and water environmental risk assessment:(1)Establishment of estuarine ecosystem health assessment theory and method system. Complex ecosystem theory was introduced; the concept of multi-estuarine ecosystem was proposed; defined the contents of estuary ecosystem health, proposed concept of estuarine ecosystem based on"Press-Status-Response"and built estuarine ecosystem health assessment system; multi-attribute assessment method based on intelligent algorithms was introduced into the estuary ecosystem health assessment. This paper established the estuary ecosystem health fuzzy assessment model based on maximum entropy (FAME), ecosystem health assessment model based on set pair analysis(SPAM) and estuary ecosystem health assessment model based on projection pursuit (PPEH), which effectively solved the characteristic problems such as randomness, fuzzy, gray, imperfection and Incompatibility of estuary ecosystem health assessment, and implemented assessment and trend analysis of estuarine health status, and provided decision-making basis for the estuary ecosystem and environment management.(2) Take the Changjiang River estuary as an example, a different scale of health assessment system was established. Health assessment system in different range was established for Changjiang river as an example. Through the establishment of biological integrity assessment index, this paper achieved a micro-state health assessment on the estuary ecosystem, proposed sediment pollution in estuaries, bottom sediment toxicity and dissolved oxygen as the basis for determining reference point; through index distribution, correlation and discrimination analysis on candidate indicators, this paper posted IBI system of Changjiang estuarine constructed by the diversity index, types, total density, total biomass, density of crustaceans and echinoderms percentage of the density. Through the principal component analysis, the assessment index system constructed by 22 indicators such as annual run-off fluctuation rate, annual sediment fluctuation rate, CODMn of sea surface, DO over standard rate, COD over standard rate, DIN over standard rate, DIP over standard rate, Benthic diversity index, zooplankton copepods density ratio, phytoplankton species of algae, fecal coliforms Secchi over standard rate was established, which can achieve estuary health assessment. This paper proposed five levels of multi-ecosystem assessment criteria, analyzed estuary ecosystem health status and developing trend by use of FAME model and SPAM models of Changjiang River, achieved the conclusion that Changjiang River estuary and adjacent waters is in the sub-healthy state of the ecosystem which validated by PPEH model analysis, and provided theory and method storage for comprehensive control of estuary ecological construction project of Changjiang River and others since Changjiang estuarine was in sub-health status.(3) Proposed water environment risk assessment and multi-criteria decision making model. Triangular fuzzy number was adopted into research on water environment sediment pollution and establishment of fuzzy assessment model (Fuzzy Assessment Model of Potential Ecological Risk,FAER) in ecological risk, which provided a new thinking and method for risk assessment of water environment sediment pollution. Multi-criteria decision model (MCDM) based on approaching ideal solution was established to solve the incompatible problem of different results. In order to couple and qualify the random uncertainty and fuzzy uncertainty of eutrophic water and evaluate environmental risk, health risk and ecological risk, this paper established an integrated fuzzy-stochastic risk assessment (IFSRA) based on risk indicators of cyanobacteria toxins - microcystin,providing an efficient method for integrated processing of different types of uncertainty,thus gave a typical risk assessment in the lower reaches of the Yangtze River.