滨海地区混盐水体富营养化主因子识别与分析——以天津市清净湖为例

水质与水体营养化程度密切相关,提炼识别其中的主要影响因素并合理控制是水体富营养化防治的有效途径.我国滨海地区地表水咸化问题突出,混盐水体(含盐量500~30000 mg·L-1)众多,其中,许多混盐水体还同时面临富营养化加剧及水华的威胁.因此,本文以天津滨海地区典型混盐水体清净湖为研究对象,通过对其水环境监测数据的统计学分析,结合藻类生长模拟实验,对其富营养化主要影响因子进行识别与分析.结果表明,总磷和矿化度为清净湖藻类生长的主要影响因子,叶绿素a浓度与矿化度呈显著负相关关系,与总磷呈显著正相关关系,以总磷和矿化度为自变量的多元线性回归模型可较好地预测叶绿素a动态.水体含盐量在15000~25000 mg·L-1的范围适宜藻类生长增殖,而当盐度小于10000 mg·L-1或大于30000 mg·L-1时,藻类生长受到抑制;在清净湖当前氮浓度水平下,磷含量增加会促进藻类生长增殖,藻类生长速率呈P3组(10∶1,氮磷比)P4组(5∶1)P2组(20∶1)P1组(50∶1)P0组(无磷培养液),氮磷比为10∶1时最适宜藻类生长.

Identification of eutrophication-controlling factors in mesohalinous waters of coastal region:A case study on Qingjing Lake of Tianjin City

Water quality has close implication with eutrophication, of which dominative factors needs to be extracted and controlled in order to take effective precautions. Mesohalinous waters (within salinity of 500~30000 mg·L^-1) prevail in numerous coastal regions of China, and most of them are under risk of severe eutrophication and algal blooms. Research was conducted taking Qingjing River as typical mesohalinous water in coastal regions of Tianjin city. To identify and analyze controlling factors for eutrophication, statistical analysis were introduced on basis of data that monitored in aquatic environments, and simulative experiments of algal-growth were completed and discussed. Results show that TP and salinity are mainly causes for algal propagation, since the concentration of chlorophyll-a exhibited apparent negative correlation with salinity while positive correlation with TP. Multiple linear regression model taking salinity and TP as independent variables can appreciably predict the profile of chlorophyll-a concentration. Results of algal-growth tests revealed that, salinity within the range of 15000~25000 mg·L^-1 was more suitable for reproduction of algal, which was inhibited once salinity lower than 10000 mg·L^-1 or over 30000 mg·L^-1. For current nitrogen abundance, increasing TP will in turn accelerate algal growth in Qingjing River with the following order:10:1(N:P)> 5:1(N:P)> 20:1(N:P)> 50:1(N:P), which further proves P-controlled eutrophication.