Eutrophication and spatial distribution of N, P and chlorophyll-a in the Taizihe River Basin, Liaohe River Catchment

Abstract

通过对太子河流域46个采样点溶解性无机氮、溶解性无机磷、总氮、总磷、电导率、pH、溶解氧和叶绿素a浓度及相关环境因子的测定，分析氮、磷浓度与叶绿素a浓度的空间分布特征，利用回归分析判别氮、磷与叶绿素a浓度的相关性，冗余分析判别河流水质与环境因子的关系，并初步评价太子河流域水体富营养化状况.结果表明：太子河流域氮、磷浓度具有明显的空间异质性，表现为上游浓度较低且变化较平稳，辽阳段浓度逐渐上升且波动增大，鞍山段浓度最高.冗余分析显示氮、磷浓度的空间分布特征与土地利用方式、海拔、河岸缓冲带宽度、植被多样性密切相关.叶绿素a浓度与氨氮、硝态氮、溶解性无机氮、溶解性无机磷、总氮、总磷和电导率呈显著正相关，说明营养盐的增多在一定程度上会促进浮游藻类的增长.太子河流域水体富营养化评价综合指数显示，太子河流域“中”营养状态点位有27个，占58.7%，“富”营养状态点位有19个，占41.3%，没有“贫”、“重富”和“极富”营养状态.;Dissolved inorganic nitrogen, dissolved inorganic phosphorous, total nitrogen, total phosphorus,conductivity, pH, dissolved oxygen and chlorophyll-a were monitored in 46 sections along the Taizihe River, Liaohe River Catchment to understand their spatial distributions. The relationships between dissolved inorganic nitrogen, dissolved inorganic phosphorous and chlorophyll-a concentration were identified using the regression analysis. The relationship between water quality and environmental influencing factors was identified using redundancy analysis.The results showed that distributions of nitrogen, phosphorous and chlorophyll-a concentration had a certain spatial-related variability.The concentration of nitrogen, phosphorous and chlorophyll-a were low and stable in the upstreams, and were increasing and fluctuating in reaches of Liaoyang. In the reaches of Anshan the concentrations were the highest. Redundancy analysis showed that the spatial distribution characteristics of N and P were closely related to the land use, altitude,width of the riparian buffer and vegetation diversity. Ammonia nitrogen, nitrate nitrogen, dissolved inorganic nitrogen, dissolved inorganic phosphorous,total nitrogen, total phosphorus, and conductivity were positively correlated with chlorophyll-a concentration. It indicated that nitrogen and phosphorous could promote the growth of alga. Eutrophication evaluation index in Taizihe River Basin showed that there were 27 sample sites in the mesotrophic level,19 sample sites in a status of eutrophication, no oligotrophic, hyper eutrophic and extremely eutrophic status.