湛江湾表层沉积物不同形态磷的变化特征

湛江湾是典型的口小腹大型海湾，早期研究表明，湛江湾呈中等磷限制潜在性富营养化。沉积物磷释放能增加水体富营养化的风险。本研究对春季和夏季湛江湾表层沉积物中的无机磷（IP）、有机磷（OP）和总磷（TP）进行了测定和分析，探讨了不同形态磷的空间分布特征和季节变化情况，并对其时空变化的影响因素进行了分析，研究结果可为湛江湾的环境保护提供科学依据和数据支持。主要研究结果如下:春季，湛江湾表层沉积物中IP、OP和TP的含量分别为236.2 μg/g、111.3 μg/g和347.5 μg/g，夏季，IP、OP和TP的含量分别为168.8 μg/g、92.4 μg/g和261.2 μg/g，3种形态磷的含量均为春季高、夏季低；两个季节的IP、OP和TP含量均在湛江湾支湾最高，沿岸海域次之，中部海域最低；IP占TP的比例在湛江湾沿岸海域和中部海域较高，OP占TP的比例在支湾较高。湛江湾表层沉积物中不同形态磷具有明显的空间分布和季节变化特征。有机质降解、河流输入、沿岸废水排放、水产养殖、沉积物粒度组成、水动力条件等是造成湛江湾表层沉积物中不同形态磷含量空间和季节变化的重要原因。

Variation characteristics of different phosphorus forms in surface sediments of Zhanjiang bay

Zhanjiang bay is a semi-enclosed bay with a very narrow entrance. Previous studies have shown that the Zhanjiang bay is at the stage of medium-phosphorus-limited potential eutrophication. Phosphorus release from sediment can increase the risk of water eutrophication. Inorganic phosphorus (IP), organic phosphorus (OP) and total phosphorus (TP) were measured in the surface sediments of Zhanjiang bay in spring and summer. The spatial-seasonal variations of these phosphorus forms and their influencing factors were studied. This study can provide scientific basis and data support for environmental protection of Zhanjiang bay. The main results were listed as follows. In spring, the average concentrations of IP, OP and TP were 236.2 μg/g, 111.3 μg/g and 347.5 μg/g, respectively. In summer, the average concentrations of IP, OP and TP were 168.8 μg/g, 92.4 μg/g and 261.2 μg/g, respectively. The concentrations of these three phosphorus forms were high in spring and low in summer. In both spring and summer, the concentrations of IP, OP and TP were highest in the channel of Zhanjiang bay, intermediate in the coastal area of Zhanjiang bay, and lowest in the central Zhanjiang bay. The percentages of IP in TP were relatively high in the coastal and central area of Zhanjiang bay. The percentages of OP in TP were relatively high in the channel of Zhanjiang bay. Different forms of phosphorus in surface sediments of Zhanjiang bay had obvious spatial and seasonal variations. Organic matter decomposition, terrestrial inputs, sewage inputs, mariculture activities, grain size compositions of sediment and hydrodynamic conditions were responsible for the spatial and seasonal variations of phosphorus forms in the surface sediments of Zhanjiang bay.