富营养化湖泊藻类氨基酸碳氮同位素组成对营养状况和初级生产力的响应

The increasingly serious problem of Lake Eutrophication attracted wide attention. In a relatively closed of eutrophic lakes, nutrient enrichment and increased of primary productivity would cause the total carbon and nitrogen isotope composition of algae gradually become positive. Total organic Carbon and Nitrogen isotopes reflect the comprehensive information of carbon and nitrogen source accumulate in organic compounds. Compared with the total organic matter, amino acids are more sensitive response to the changes of nutritional status and primary productivity in lakes. Our existing research found that, when the total nitrogen content in the water increases from 3.15 mg/l to 5.23 mg/l, the nitrogen isotopes of characteristic amino acids (aspartic, glutamic, alanine, and arginine) were positive from 1.8‰ to 3.9‰, and the total nitrogen isotope value did not change significantly, indicating that amino acids have the potential to indicate changes in lake nutrient status and primary productivity. This foundation intends to select three different nutritional statuses of small and medium-sized lakes in the edge of Poyang Lake as objects. Analyzing amino acid composition, content and isotopic values in different periods, combining several parameters, such as dissolved inorganic carbon, NH4+ and NO3− Content, and carbon nitrogen isotope values, as well as chlorophyll-a content and phytoplankton biomass. Exploring the relationship between nutritional status and primary productivity with amino acid, and searching for the evidence of amino acid could responses the change of nutritional status and primary productivity. This project is expected to provide scientific basis for the evaluation of Lake Eutrophication and predicting algae bloom.

日趋严重的湖泊富营养化问题受到人们广泛关注。研究证实，相对封闭湖泊中，营养盐富集和初级生产力提高将导致藻类总有机碳氮同位素值逐渐偏正。与总有机质相比，氨基酸是藻类生长过程中碳氮源合成的瞬时产物，能更加灵敏的响应湖泊营养状态及初级生产力变化。申请人现有研究发现，当水体总氮含量从3.15增加到5.23mg/l时，特征氨基酸（天冬氨酸、谷氨酸、精氨酸等）氮同位素值偏正1.8‰到3.9‰，而总氮同位素值变化并不明显，表明氨基酸具有指示营养状况和初级生产力变化的潜力。本项目拟选取鄱阳湖边缘三个不同营养状态且相对封闭的中小型湖泊为对象，分析不同时期藻类氨基酸组成、含量和同位素值；结合溶解无机碳、氨盐、硝酸盐含量和碳氮同位素值；及反映初级生产力的指标。探讨藻类氨基酸与湖泊营养状态和初级生产力之间关系，寻找氨基酸响应营养状态及生产力变化证据。本项目有望为湖泊富营养化评价、预测藻华爆发等提供科学依据。

日趋严重的湖泊富营养化引起的一系列环境问题受到人们广泛关注。为了减少湖泊富营养化带来的生态危害和健康风险，提前进行藻华爆发预测并采取相应对策是关键。藻类生长受控于环境因素的改变，当这些环境指标达到某一临界值时，就有藻华爆发的风险。一般情况下，通过监测这些环境指标变化就能对藻华爆发进行初步预测。但是有些情况下，藻华爆发对某些环境因素的响应具有不确定性。发展相对简单的有效的生物监测方法作为辅助手段，将有助于补充藻华爆发预测的方法。本项目选取鄱阳湖边缘三个不同营养状态且相对封闭的中小型湖泊为对象，分析不同时期藻类氨基酸组成、含量和同位素值；结合铵盐、硝酸盐含量和碳氮同位素值；及反映初级生产力的指标。探讨藻类氨基酸与湖泊营养状态和初级生产力之间关系，寻找氨基酸响应营养状态及生产力变化证据。我们的结果显示，鄱阳湖边缘的三个湖泊中，有两个湖泊在秋季氮源相对稳定条件下，表现出初级生产力提高时藻类游离氨基酸氮同位素值逐渐偏正的特征，并且偏正幅度大于结合态氨基酸氮同位素和总氮同位素，这与我们培养实验的结果一致。表明与总有机质和结合氨基酸相比，游离氨基酸(藻类生长过程氮源合成的瞬时产物)，能更加灵敏的响应湖泊营养状态及初级生产力变化。游离氨基酸具有指示湖泊营养状况和初级生产力变化的潜力。本项目可以为区域湖泊富营养化评价、预测藻华爆发等研究提供帮助。