Li Zhao-Fu, Liu Hong-Yu, Li Heng-Peng
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Huan Jing Ke Xue. 2012 Nov;33(11):3753-9.
Focused on understanding the function of wetland in improving water quality, Pingqiao watershed and Zhongtian watershed in Tianmu Lake drinking water sources area were selected as the research region. We integrated remote sensing, GIS techniques with field investigation and chemical analysis to analyze the relationship between wetland and water quality in watershed scale. Results show: (1) There are many wetland patches in Pingqiao and Zhongtian watershed, wetlands patch densities were respectively 7.5 km(-2) and 7.1 km(-2). Wetlands widely distributed in the Pingqiao watershed with mostly located away from the river of 500 m, whereas wetlands relatively concentrated in the lower reach within 500 meters of riverside in Zhongtian watershed. (2) Nitrogen and phosphorus nutrient retention of wetland in watershed scale was significant. The annual mean TN and DTN concentration had a strong relationship with percent area of wetlands in Zhongtian watershed while the weakest relationship was found with TP and DTP concentrations, especially, the mean TN and DTN concentrations in spring and winter had the significantly negative relationship with wetland areas of watershed. The negative relationship was existed for nitrogen in autumn of Pingqiao watershed, which suggested that watersheds varying in area of wetlands have the different nutrient reducing efficiency in seasonal periods. (3) A certain number and area of wetland will improve river water quality in watershed scale, which can instruct water environment treatment. However, considering the complexity of nutrient transport processes in watershed, wetland-related factors such as area, location, density, ecosystem structure and watershed-related factors such as temporal interval, spatial scales, slope and land use will impact on the transport processes, and related theoretical and practical problems need further research.
以天目湖饮用水源地平桥流域和中田流域为研究区域，聚焦于理解湿地在改善水质方面的作用。我们将遥感、地理信息系统技术与实地调查和化学分析相结合，在流域尺度上分析湿地与水质之间的关系。结果表明：（1）平桥和中田流域有许多湿地斑块，湿地斑块密度分别为7.5平方千米-2和7.1平方千米-2。湿地广泛分布于平桥流域，大多距离河流500米以外，而中田流域的湿地相对集中在距河边500米范围内的下游区域。（2）流域尺度上湿地对氮磷养分的截留作用显著。中田流域年平均总氮（TN）和溶解态总氮（DTN）浓度与湿地面积百分比有很强的相关性，而与总磷（TP）和溶解态总磷（DTP）浓度的相关性最弱，特别是春季和冬季的平均TN和DTN浓度与流域湿地面积呈显著负相关。平桥流域秋季氮素存在负相关关系，这表明不同湿地面积的流域在不同季节的养分削减效率不同。（3）一定数量和面积的湿地在流域尺度上能改善河流水质，这可为水环境治理提供指导。然而，考虑到流域内养分输移过程的复杂性，湿地相关因素如面积、位置、密度、生态系统结构以及流域相关因素如时间间隔、空间尺度、坡度和土地利用等都会对输移过程产生影响，相关理论和实际问题有待进一步研究。
