樟湖库湾网箱养殖对底层水体氮磷营养盐变化的影响

Effect of cage culture on the changes of nitrogen and phosphorusin bottom water of Zhanghu reservoir bay

根据2018年4月、7月和10月对樟湖库湾网箱养殖区水体水环境的调查,分析了网箱养殖区底层水体氮(N)、磷(P)营养盐的季节变化,并利用综合营养状态指数对水体的富营养化状态进行了评价。结果表明,樟湖库湾网箱养殖对底层水体温度、透明度(SD)、高锰酸盐指数(CODMn)和溶解氧(DO)影响较小;与对照区相比,网箱养殖区春季增加水体叶绿素a,夏季增加pH值。樟湖库湾网箱养殖区总氮(TN)、总磷(TP)和无机氮(DIN)季节平均值均高于对照区,而PO4^3--P与对照区没有显著差异(P>0.05)。养殖区和对照区的TN、TP、氨氮(NH+4-N)、硝态氮(NO-3-N)和亚硝态氮(NO-2-N)浓度呈现从春季到秋季逐渐降低的季节变化趋势;养殖区PO4^3--P夏季高于其他季节。富营养化评价结果表明,樟湖库湾网箱养殖区底层水体春季和夏季达到重度富营养水平,秋季属于中度营养化水平。

Based on the data from water environment in the cage culture area of Zhanghu reservoir bay surveyed in April,July and October 2018,the seasonal changes of nitrogen(N)and phosphorus(P)in the bottom water of cage culture area were analyzed and the state of eutrophication of water body was evaluated by using comprehensive nutrition state index.The results showed that there was no significant effect on the temperature,transparency(SD),CODMn and dissolved oxygen(DO)of the bottom water of cage culture in Zhanghu reservoir bay,while the culture area significantly increased pH in summer and chlorophyll a in spring,respectively.The concentrations of seasonal mean values of total nitrogen(TN),total phosphorus(TP)and total inorganic nitrogen(DIN)in the cage culture area of Zhanghu reservoir bay were higher than those in the control area,while there was no significant difference in the concentration of PO4^3--P between the cage culture area and the control area(P>0.05).The concentrations of TN,TP,ammonia nitrogen(NH+4-N),nitrate nitrogen(NO-3-N)and nitrite nitrogen(NO-2-N)in the cage culture area and the control area showed a seasonal trend of decreasing from spring to autumn.The concentration of PO4^3--P in summer was higher than that in other seasons in the cage culture area.The results of eutrophication evaluation showed that the water quality of the cage culture area was the heavy eutrophication level in spring and summer and the moderate eutrophication level in autumn,respectively.