大辽河口水环境污染生态风险评估

河口生态系统位于河流入海口,是介于河流和海洋之间的生态交错区,也是人类活动集中的区域。针对目前河口生态风险研究较多沿用陆地生态系统模式,并忽略风险分布的空间异质性等问题,以大辽河口为研究区,建立具有针对性的河口区(河海交错区)生态风险评价模型,以盐度和污染源作为划分河口不同区段的主要因素,对不同水期大辽河口生态风险及其空间分布进行有效评估,探讨河口区生态风险时空分布差异规律。结果表明,大辽河口整体生态风险水平相对偏高(三时段风险平均值为0.56),在0至1的生态风险指数空间中超过中等风险水平;就时间尺度上而言,造成大辽河口区生态风险差异的主要原因是径流量;就空间尺度而言,大辽河口区生态风险空间分布受上游来水携带污染物、下游污染源排放以及入海口门段海水稀释作用三者共同影响。因此,从根本上讲,改善并提高河口区域的生态风险水平,应密切关注人类活动对河口态系统造成的不良影响,并应以提高整个流域整体生态状况为根本目标和途径,这样才有助于从根本上解决产生河口区域生态风险的环境问题。

Integrated water risk assessment in Daliao River estuary area

Estuarine ecosystem is the ecotone between the river and ocean, which is under tremendous influences of concentrated human activities. Now, most estuarine ecological risk studies are based on the terrestrial ecosystem model, ignoring spatial heterogeneity distributing laws. This paper takes Daliao River as the study area and establishes a targeted estuary ecological risk evaluation model. Considering the scale request, the assessing technology mainly includes four steps: confirmation and analysis of study area, identification and analysis of risk sources, analysis of exposure and ecotoxic effects, and integrated estimation of ecological risks. Then the evaluation system is built up, which includes indices of biodiversity, afflux material, comprehensive pollution, and pressure index of socio-economic development. Combining the method of AHP, Principal Component Analysis and Polarized Standardization, the integrated index of ecological risk can afterwards be figured out. This model takes salinity and pollution sources as the major factors in the divisions of different sections and different water periods. And then this article effectively assesses the spatial distribution of ecological risk in Daliao River estuary, and explores the spatial and temporal distribution laws of estuarine ecological risk. The results show that, on the whole, the ecological risk of Daliao River estuary area is relatively high (the average risk value of three water periods is 0.56), which is over the middle level in 0 to 1 of the ecological risk index space; on time scale, the runoff is the main factor resulting in the ecological risk difference; on the spatial scale, the ecological risk index is affected by the pollutants carried by runoff of upstream, downstream pollution emissions and dilution water at the mouth the river together. In order to improve the environmental condition of the estuary area, more attention should be paid to the adverse effects of human activities on the estuarine ecosystem and improve the ecological conditions of the whole valley, thus the environmental problems of estuarine ecosystem can be solved fundamentally.