浙江省铜山源水库水体偏碱污染成因研究

Study on cause of meta-alkalescence pollution of Tongshanyuan Reservoir in Zhejiang Province

针对中国东南丘陵地区水库出现不同程度的水质偏碱,部分水库在局部时段内水体pH值指标频繁超出地表水质量标准的问题,以浙江衢州大(2)型水库铜山源水库为例,实施水质监测和水生态调查。通过水文、气象、水质、水生态指标之间的相关性分析,揭示了自然环境本底水质、关键气象水文过程、外源污染以及藻类生长对水库水质偏碱污染的影响机制。结果表明:铜山源水库水体偏碱污染具有长期性的特征,且在每年的4~8月偏碱现象最为严重。水库周边自然环境下的本底水质偏碱,铜山源水库入库河流水体pH值高达8.02~8.47,局部时段高于地表水标准值。库区水体pH值指标与水温、DO、营养性物质(TP、TN)、叶绿素a等指标在一定程度上随着时间变化呈现出同步升降的正相关性。pH值变化受多种因素的综合影响,主要表现为直接或间接地促进藻类光合作用增强,导致光合作用效应大于水体水生动植物的呼吸作用,从而导致水体偏碱污染。

In recent years,reservoirs in the hilly areas of southeastern China have been polluted by meta-alkalization in varying degrees,and the pH values of some reservoirs have frequently exceeded the environmental quality standards of surface water during some periods of time.Taking Tongshanyuan Reservoir,a large(second)type reservoir in Quzhou City,Zhejiang Province as an example,water quality monitoring and water ecology investigation were conducted,and the correlation analysis among hydrology,meteorology,water quality and water ecology indicators were combined to reveal the influence mechanism of background water quality of the natural environment,the key meteorological and hydrological processes,the exogenous pollution and the growth of algae on the meta-alkalization pollution of the reservoir.The results showed that the meta-alkalization pollution in Tongshanyuan Reservoir had lasted for a long time and was more serious from April to August every year.The background water of the natural environment around the reservoir was alkaline.The pH values of the inflow rivers were as high as 8.02 to 8.47,which was higher than the surface water standard in some time.The pH values of water in reservoir showed a relatively positive correlation to water temperature,DO,nutrients(TP,TN),chlorophyll-a to a certain extent,which rose and fell in synchronization with the change of time.Changes in the pH value of the water body were influenced by a variety of factors,which were mainly manifested in the direct or indirect enhancement for algal photosynthesis,leading to a greater effect of photosynthesis than respiration of aquatic organisms,which resulted in meta-alkalization and pollution of the reservoir water body.