官厅水库生物固氮作用对水体富营养化的响应

Response of Biological Nitrogen Fixation to Eutrophic Water in Guanting Reservoir

以官厅水库富营养化水体为研究对象,利用乙炔还原法测量水体生物固氮能力,结合变性梯度凝胶电泳（DGGE）技术对固氮生物nifH基因进行分析。实验结果表明,官厅水库水体存在生物固氮现象,固氮速率为0.172-9.35 nmol/（m3.d）,与水体氨氮、总氮、总磷呈显著相关性（P=0.998,r=0.000;P=0.986,r=0.000;P=0.968,r=0.002）。DGGE图谱显示：各点固氮细菌丰度差异较大,Shannon-Weaver指数为0.80-2.45,固氮细菌丰度和总氮、总磷存在较强相关性（P=0.737,r=0.094;P=0.787,r=0.063）。随着水体富营养水平的上升,固氮微生物多样性急剧增加,水体固氮能力也随之上升。自然固氮可能对原本富营养化的水体产生更大危害。

In Guanting reservoir,biological nitrogen fixation rate（NFR） was measured with acetylene reduction method,the diversity of nitrogen fixation bacteria（NFB） was revealed with nifH gene PCR-DGGE fingerprint.The results showed that biological nitrogen fixation exists in Guanting reservoir,the rates of nitrogen fixation ranged from 0.172 to 9.35 nmol/（m3·d）.There was a positive correlation between NFR and NH＋4-N（P=0.998,r=0.000）,TN（P=0.986,r=0.000）,TP（P=0.968,r=0.002） concentrations,respectively.DGGE fingerprint indicated the（NFB） abundance differed between six sites and positive correlations were found between NFB abundance and TN（P=0.737,r=0.094）,TP（P=0.787,r=0.063）.Shannon-Weaver index varied in a range of 0.80-2.45.During the process of eutrophication in reservior,nitrogen fixation bacteria diversity increased with the nutrient status and thereby NFR enhanced.In addition,biological nitrogen fixation could aggravate eutrophication in Guanting reservoir.