宁波南沙港网箱养殖水域营养状况评价及生物修复策略

Nutrient Condition Assessment and Bioremediation Strategy to the Marine Fish Cage Culture Area in Nansha Bay

根据2007年1月-2007年11月4个航次对宁波南沙港网箱养殖水域水体营养盐(NO2--N、NO3--N、NH 4+-N和PO34--P)含量的监测结果,利用营养指数E法对水体的富营养化状态进行了评价。根据网箱养殖系统物质平衡方程和现场调查实验数据,估算了南沙港网箱养殖水域的氮磷污染负荷,以溶解态氮作为平衡指标,估算了鱼藻类合理的配比模式。结果表明,南沙港水体中NO2--N、NO3--N、NH4+-N、PO4-P含量年变化范围分别为0.26μmol/L～4.86μmol/L,33.93μmol/L～82.86μmol/L,0.59μmol/L～7.86μmol/L,1.47μmol/L～2.97μmol/L,不同养殖区之间营养盐含量差异不显著(p<0.05);营养指数E值年变化范围介于2.41～15.99之间,表明该港水体处于重度富营养化状态;养殖区N/P值的年平均值为32.95,表明南沙港海区是一个氮过剩的养殖系统。南沙港网箱养殖水域氮、磷的负荷量分别为70.43 t/a和5.96 t/a,其中溶解态氮、磷负荷量分别为49.3 t/a和2.38 t/a;南沙港的藻类养殖面积需要在现有基础上再扩大0.44倍,达到107.52 ha,才可以与网箱养殖系统的氮磷污染负荷构成平衡;网箱养殖个数与藻类养殖面积(ha)的合理配比约为1∶0.027。

Based on the basis of field data measured during 4 cruises from January 2007 to November 2007,variations in the characteristics of dissolved inorganic nitrogen and phosphate in Nansha aquaculture area,Ningbo city,China were analyzed.Moreover,the nutrition condition was assessed by mean of eutrophication index method.And also,the loads of nitrogen and phosphorus in marine cage culture system in Nansha Bay were estimated.Dissolved nitrogen was selected as the main parameter to calculate the suitable ratio of macroalgae and fish for absorbing the nutrient load coming from fish culture cage.Results showed that the annual concentrations of NO-2-N,NO-3-N,NH＋4-N,PO4-P ranged between 0.26 mol/L^4.86 mol/L,33.93 mol/L^82.86 mol/L,0.59 mol/L^7.86 mol/L,1.47 mol/L^2.97 mol/L,respectively.There were no significant differences among different stations.Eutrophication index（E） value ranged from 2.41 to 15.99 which indicated the area was in serious eutrophication conditions.The annual average value of N/P was 32.95,which indicated a nitrogen surplus in this mariculture area.The nitrogen and phosphorus load were 70.43 t/a and 5.96 t/a,while the load of dissolved nitrogen and dissolved phosphorus were 49.3 t/a and 2.38 t/a,respectively.The macroalage culture area should be expanded from 74.67 to 107.52 ha so as to reduce the nutrient pollution caused by fish culture.According to the assess,The optimal co-culture ratio of fish cage to macroalage in this bay was suggested to be 1 cage with 0.027 ha of kelp.