象山港大黄鱼Pseudosciaena crocea网箱养殖区沉积物-水界面营养盐通量研究

2013年5月、8月和11月调查了象山港大黄鱼网箱养殖区及附近沉积物中总有机氮(TON)、总有机碳(TOC)和总磷(TP)含量,并采用实验室模拟法研究了底泥耗氧率(SOCs)和沉积物-水界面营养盐(NH⁺₄、NO^-₂+NO^-₃和PO^3-₄)通量。结果表明:养殖区(YZ)沉积物中的TON和TP含量显著高于距离养殖区50 m(F1)和100 m(F2)的区域(P<0.05)。底泥释放NH⁺₄到上覆水中,但是从上覆水中吸收NO^-₂+NO^-₃和PO^3-₄。沉积物-水界面营养盐通量表现出明显的季节性变化,在8月,NH⁺₄及PO^3-₄的释放量达到最大值。上覆水中NH⁺₄、NO^-₂+NO^-₃和PO^3-₄的质量浓度随着沉积物-水界面营养盐通量的变化而变化。研究表明,象山港大黄鱼养殖活动对养殖区底泥造成了一定污染,且通过影响沉积物-水界面营养盐通量影响上覆水中营养盐分布,最终给整个养殖系统造成生态负担。

Study on nutrient fluxes of sediment-water interface in cage culture zone of large yellow croaker Pseudosciaena crocea in Xiangshan Bay

Undisturbed sediment samples were collected from the cage culture zone and nearby of large yellow croaker' farm in Xiangshan Bay in May, Aug. and Nov. of 2013. Total organic nitrogen (TON), total organic carbon (TOC) and total phosphorus (TP) in the sediments were determined. A simulated experiment was conducted to study the sediment oxygen consumption (SOCs) rates and nutrients(NH⁺₄、NO^-₂+NO^-₃、PO^3-₄) fluxes between water column and sediments. TON and TP values of sediment in cage-zone(YZ) are generally significantly higher than those in stations of 50 m away (F1) and 100 m away (F2) (P<0.05). The sediments release NH⁺₄ to the overlying water where as they takes up NO^-₂+NO^-₃ and PO^3-₄. Benthic fluxes show that intensive seasonal variations and the release of NH⁺₄and PO^3- ₄reach peak values in August, which response to increased organic input due to the yellow croaker farming. The nutrient concentration in water changes with benthic nutrient fluxes among seasons. The results obtained in this study imply that the ongoing aquaculture activities have led to sediment organic pollution at certain extent and the polluted sediment could affect the benthic nutrient fluxes, which might cause the redistribution of nutrients in water column.