Regional Ecological Risk Assessment And Management

Ecological risk assessment is a new rising field of research after the1990s.It is not only an important branch of environmental risk assessment, but also the scientific basis of environmental management and decision making. Ecological risk assessment is a process that evaluates the possibility that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors, and its research is involved in many subjects including environmental science, ecology, environmental and ecological toxicology, geography, disaster science etc. Regional ecological risk assessment, as a significant branch of ecological risk assessment, is defined to describe and evaluate the impact on ecosystem structure and function by environmental pollution, human activities and assess possibility and level of hazard. Regional ecological risk assessment plays an important role in protecting ecological environment, maintaining public health and developing economy. And is the important guarantee to realize the coordination, sustainable, and stable development of society, economy and environment. Ecological risk assessment offers a scientific basis for the government making environmental policy.Area near Yangtze River is to be located at the lower reaches of the Yangtze River Delta region, where is populous and fast developing. Meanwhile, during the high speed of economic and social development, regional complex ecosystem faces enormous pressure, such as the rapid decrease of cultivated land, serious environmental pollution, natural disasters and environmental accident, which restrict regional social and economic sustainable development. Taking this area to study ecological risk assessment can be concentrated reflection by both natural and anthropogenic activities to the ecological system’s characteristics and changing rules.Taking Jiangsu part of the Yangtze River as a research zone, on the basis of historical textual criticism and remote sensing image classification of landscape, in connection with the characteristics of natural geography, socioeconomic and ecological environment of area near Yangtze River, in view of basic principles of risk measurement and the frame work of regional ecological risk assessment, this paper separately built integrated value of ecological risk calculation models of both probability risk sources and evolutionary risk sources to research regional ecological risk assessment, and classified the results then draw the risk spatial distribution map, at last put forward the countermeasures of ecological risk management and landscape ecological construction recommendation. Through the empirical analysis, it is concluded that regional ecological risk assessment can provide prospective direction for the improvement and maintenance of regional ecological environment.Jiangsu part of the Yangtze River faces all kinds of natural disasters, such as Flood and water-logging, drought, agriculture and forestry blight, and also artificially induced risk accidents, as toxic and harmful chemical substances leaking, exploding, fire and oil spill. This kind of risk can be described by probability of occurrence. According to the basic principles of risk measurement, this paper built a probability model of regional ecological risk assessment, and analyzed relative risk value and spatial distribution. The results showed that, the highest risk zones of probability model ecological risk were found to be in Jurong and Nanjing. The main reasons for this could be high risks of environmental accidents and fires accidents. Environmental accidents risk had the highest comprehensive probabilities of four main sources, which contributed most to probability model ecological risk and brought a higher risk for Jurong and Nanjing. In the assessment results of four main risk sources, Yizheng had three results in higher risk zones, so its comprehensive result was also found in the higher risk zone. It was also found that probability model ecological risk has a dispersion of distribution of Jiangsu part of Yangtze River, which suggested that probability risk sources had a dispersion of distribution in this area and had a potential thtreat to this area. Under certain condition, each singel risk source could be the area’s main risk source and could be serious threaton. Hence, it’s highlt suggested that administrative department maturities the relevant planning, to concern ecological sensitive area and densely populated area, to evacuate major risk sources, meanwhile, to prepare emergency plans incase to act positive response once risk happens.Besides probability risk, evolutionary risk is another main form of ecological risk in area near Yangtze River, which mainly displays in the pressure to region complex ecosystem by human development and utilization and the resultant potential ecological harm. Based on the method of relative risk model (RRM), this research developed a regional ecological risk assessment model of evolutionary risk sources, and compared development and utilization before and after in the study zone, and analyzed relative risk value and spatial distribution. Results are given as follows. The highest risk zones of land use change were found to be in Changzhou, Jiangyin, Zhangjiagang and Nantong. The main reasons for this could be the highest increase proportion of land for construction. The highest risk zones of pollutants emission change were found to be in Yizheng, Jurong, Jiangyin and Haimen. However, the risk values of pollutants emission change were negative in Yangzhong, Changshu, Taixing and in Nanjing. The main reasons for this could be these cities strengthen the power of pollution control to reduce the pollutants emission intensity. Changzhou, Nantong and Jiangyin showed a high comprehensive ecological risk value, and the second highest zone was in Zhangjiagang. Land use change was the main reason for high comprehensive ecological risk in Changzhou, Zhangjiagang and Jiangyin, whereas the main reasons for high comprehensive ecological risk in Nantong were both land use change and pollutants emission change. Regarding spatial distribution of the comprehensive ecology risk, the values showed higher in south bank of Jiangsu part of the Yangtze River than in north bank of Jiangsu part of the Yangtze River.At last, this paper synthesized the results of both probability and progressive ecological risk assessment and recommended pertinent advices.