长江上游小型水库枯水期水质对景观组成、配置和水库特征的响应

Response of Water Quality in Small Reservoirs to Landscape Composition,Landscape Configuration,and Reservoir Characteristics in the Upper Reaches of the Yangtze River During Dry Season

长江流域小型水库数量多分布广,具有重要的生态经济效益,探明小型水库水质对环境变量的响应规律对于提升水库水质具有非常重要的意义.基于长江上游36个小型水库枯水期水质数据,运用相关分析和冗余分析等研究方法,将环境变量划分为景观配置指标、景观组成指标和水库特征指标这三大类,探明其对水质指标变化的影响.结果表明:(1)旱地是NO_(3)^(-)-N、TN和TP的主要来源;居民点是TP物质的主要来源;水田、林地和荒草地对水库N、P的截留和净化具有正向作用;(2)旱地最大斑块指数与水库TN和NO_(3)^(-)-N浓度显著正相关,水田散布与并列指数、林地散布与并列指数与水库NO_(3)^(-)-N和TN浓度显著负相关;旱地斑块密度与TP物质含量显著正相关;林地最大斑块指数与TP含量显著负相关;(3)水库库容、水库平均深度和水库形状指数对水库水质提升具有显著的正向作用;(4)水库环境变量中,景观配置指标对水库水质指标变化的解释率最高(24%),其次是水库特征指标(11%),最后为景观组成指标(9%).流域因素是影响水库水质变化的关键因子(55%),内部因素(19%)对水库水质的影响同样不可忽视.研究结果可以为通过管理和优化水库景观特征来控制小型水库水质退化提供理论依据.

Small reservoirs in the Yangtze River are large in quantity and widely distributed,which have important ecological and economic benefits.It is of great significance to explore the response law of small reservoir water quality to environmental variables for improving reservoir water quality.Based on the measured water quality data of 36 small reservoirs in the upper reaches of the Yangtze River,combined with the measured water quality data,using correlation analysis,redundancy analysis,and other research methods,we divided the environmental variables into three categories:landscape configuration index,landscape composition index,and reservoir characteristic index,and explored their impact on the change in water quality index.The research results showed that:①farms were the main source of NO_(3)^(-)-N,TN,and TP,and residential land was the main source of TP.Paddy,forest land,and wasteland had positive effects on the retention and purification of N and P in reservoirs.②The LPI of farms was significantly positively correlated with the concentrations of TN and NO_(3)^(-)-N in the reservoir,and the paddy and forest were significantly negatively correlated with the concentrations of NO_(3)^(-)-N and TN in the reservoir.The PD of farms was positively correlated with TP.The LPI was negatively correlated with TP content.③The correlation between average reservoir depth and reservoir water quality was the strongest.Reservoir capacity,reservoir average depth,and reservoir LSI had significant positive effects on water quality improvement.④Among the environmental variables of the reservoir,landscape configuration index had the highest explanatory rate(24%),followed by that of the reservoir characteristics index(11%)and landscape composition index(9%).Watershed factors were the key factors(55%),and internal factors(19%)also had a significant influence on reservoir water quality.The research results can provide a theoretical basis for controlling water quality degradation of small reservoirs by managing and optimizing the landscape characteristics of reservoirs.