黄河呼和浩特段水体污染风险评估及其发生特性

通过建立风险评估模型、风险分级级别,对2011—2013年黄河呼和浩特段不同断面、时间和指标的水质数据进行时空分布上的水体污染风险分析。结果表明:水污染风险时空分布不具有相关性,但有较强的局地性、偶发性、变化性;常规指标、金属指标、有机化合物指标、阴离子及盐类指标在时间、空间上的水污染风险值分别为5.71~7.28、1.94~17.58,1.37~1.60、0.21~1.72,1.30~0.87、0.68~3.18,1.18~1.44、0.68~0.86;浑津桥、小入黄口断面处的污水排放致使常规指标在主干流、各支流均处于高风险状态,但其他3类指标均处低风险水平及以下,且整体上各支流风险程度高于主干流。如若无重大污染事件发生,则各项指标风险值较低且稳定,也无水污染风险事件引发的趋势。

Risk Assessment and Genetic Characteristics of Water Pollution of the Yellow River at Huhhot, China

The Yellow River at Huhhot has suffered from industrial and agricultural pollution. Here we adopted the existing Chinese environmental standards and water pollution indexes to perform risk assessment of this water body. Eco-systems and human health index were taken as receptors. Risk assessment model and risk grades were applied to temporal and spatial risk assessments of water pollution based on the water quality data of different sections, different time and different indexes of the Yellow River, Huhhot from the year 2011 to 2013. The results were also compared by using risk index assessment method, probabilistic risk assessment method, and genetic mutation caused by accident model assessment based on the key pollutant monitoring data. Water pollution risk did not show obvious temporal and spatial distributions, but had a strong localization, contingency and variability. The temporal and spatial variation of water pollution risk values were 5.71~7.28, 1.94~17.58;1.37~1.60, 0.21~1.72; 1.30~0.87, 0.68~3.18; 1.18~1.44, 0.68~0.86 for conventional index, metal index, organic compound index, and anion and salt index, respectively. High wastewater discharge at the sections of Hunjinqiao and Xiaoruhuangkou in which the concentrations of BOD, COD and TN were comparatively high led to a highly risk of conventional index in both the main stream and the related tributaries. However, other 3 indexes were at a low or below risk levels. Overall, the risk degree was greater in the tributaries than in the main stream.