青海湖氮素分布特征及其对藻类生长的影响

以青海湖水体的11个样点为研究对象,测定不同形态氮素(总氮、硝酸盐氮、亚硝酸盐氮、氨氮)质量浓度、藻类数量及叶绿素质量浓度,同时测定其他相关因子,并对氮素对藻类生长的影响进行分析。结果表明:青海湖水体中总氮、硝酸盐氮及氨氮质量浓度分别为0.80mg/L、0.28 mg/L和0.20mg/L,且湖心区(深水区)样点质量浓度大于岸边区(浅水区)样点,浅水区植物生长及沙柳河等外源输入均对氮素质量浓度有一定程度的影响;亚硝酸盐氮质量浓度为9.70μg.L-1,浅水区质量浓度高于深水区;浅水区氨氮的氧化作用可能是亚硝酸盐氮质量浓度在浅水区高于深水区的主要原因,同时溶解氧是此过程的限制因子;水体氮素与藻类数量为显著的负相关性,但与叶绿素质量浓度为显著正相关性。青海湖水体不同形态氮素分布具有不同特征,且氮素对藻类的生长和繁殖具有不同的影响。

Particular specific features of nitrogen distribution and their effect on alga growth in Qinghai Lake

The aim of present study is to investigate the characteristic features of nitrogen distribution and explore ways for assessing their effects on alga growth by taking Qinghai Lake as a case study.In doing our research,we have established 11 sampling sites and four different forms of nitrogen(total nitrogen,nitrate nitrogen,nitrite nitrogen and ammonia) content,the quantity of alga and the content of chlorophyll A and other relevant water quality influential factors.The results of our experiments show that the total nitrogen,nitrate nitrogen and ammonia nitrogen content were 0.80 mg/L,0.28 mg/L and 0.20 mg/L respectively in the lake water.Moreover, the concentration of total nitrogen,nitrate nitrogen and ammonia nitrogen content in the deep water area prove to be higher than in the shallow water area,which m ay account for the plant growth in the shallow water area and the input of exogenous nitrogen,such as that from Shaliu river,which may influence the content of nitrogen in lake.The content of nitrite nitrogen equals 9.70 μg/L,which turns to be higher in the shallow water area than in the deep one, which may account for the process of ammonia oxidation.During this process,the dissolved oxygen tends to be the primary limited factor.In addition,we can also find the significant negative correlation(p<0.001) between the nitrogen content and the amount of alga,whereas the correlation(p<0.01) recorded between content of nitrogen and chlorophyll A is positive by nature.Thus,the present study proves that the above said four forms of nitrogen(total nitrogen, nitrate nitrogen,nitrite nitrogen and ammonia) are actually displaying different distribution characteristics and in turn have different effects on the growth and reproduction of alga in the lake.