广东流沙湾网箱养鱼区水体氮磷的时空变化及负荷估算

研究流沙湾网箱养鱼区水体氮、磷含量的月变化和水平分布,并运用质量平衡方程估算其氮、磷负荷。结果表明:总氮变化在0.212~0.892 mg/L之间,平均0.498 mg/L;总磷变化在0.009~0.036 mg/L之间,平均0.020mg/L;氮磷比变化在23.6~26.1之间,平均为25。在5-9月,氮、磷含量变化呈逐渐增加趋势,到9月达到最大,10月又减少。网箱内部氮、磷的含量高于网箱外部,并随着与网箱距离的增大而逐渐减小。红鳍笛鲷(Lutjanus argentimaculatus)、紫红笛鲷(Trachinotus ovatus)和卵形鲳鲹(Lutjanus erythopterus)全鱼的氮质量分数平均为2.42%,磷质量分数平均为0.26%,饵料系数为6.67,流沙湾网箱养鱼养殖期产生的氮、磷负荷平均分别为135.8和19.4 kg/t。

Temporal and Spatial Variation of Nitrogen and Phosphorus and Their Load Estimation in Cage-culture Waters in Liusha Bay,Guangdong

Nitrogen and phosphorus concentration of water were determined in fish cage-culture area and its vicinity in Liusha Bay from May to October 2013 on monthly basis. At the same time, the nitrogen and phosphorus content in fanning fish and trash feed fish. The results showed that total nitrogen varied between 0.212-0.892 mg/L with an average 0.498 mg/L; total phosphorus varied between 0.009- 0.036 mg/L, and had an average of 0.020 mg/L, ratio of nitrogen to phosphorus varied between 23.6-26.1 with an average 25. From May to September, nitrogen and phosphorus content appeared an increasing trend, and reached its maximum by September, and reduced in October. Nitrogen and phosphorus content inside the cages were over than that outside the cage, and gradually decreased with increasing distance from the cage. The mass fraction of nitrogen of whole fish of Lutjanus erythopterus, Lutjanus argentimaculatus, and Trachinotus ovatus, were 2.42% on average, and their average phosphorus were 0.26% with feed conversion ratio of 6.67. Nitrogen and phosphorus loads in this area were 135.8 kg / t and 19.4 kg / t on average.