考虑泥沙影响的污染物输运年龄数值模拟

Numerical simulation on the transportage of pollutants accounting for the role of sediment

自然水体中污染物的迁移、转化规律与经泥沙吸附后的沉降、再悬浮等泥沙过程密切相关,其机制尚不明确。采用污染物输运年龄对泥沙影响进行了量化分析,并应用于南黄海辐射沙脊群西洋海域。基于水体中泥沙-污染物模型,推导了考虑泥沙影响的污染物输运年龄的计算方程,通过数值模拟分析了污染物分配系数KD对污染物输运年龄空间分布的影响。研究成果表明:计入泥沙影响后,污染物浓度显著减小,污染物输运年龄随之增大,表明泥沙对污染物扩散起阻碍作用;污染物分配系数KD表征泥沙吸附能力,污染物输运年龄与其呈一定的正相关性,当该系数达到一定值(KD=10^3L/g)时,泥沙吸附能力趋于饱和,污染物输运年龄不再发生显著改变。

The transport patterns of pollutants in natural bodies of water are closely correlated with deposition and resuspension processes of sediment,to which the pollutants attach,and yet the influences of sediment on the transport of pollutants have not been fully studied. We here used transport age to quantify the influences and applied these findings to the Xiyang Sea area of the radial sand ridges in the South Yellow Sea. The governing equations of transport age considering sediment s impacts were derived from sediment-pollutant interaction model. Numerical simulation resolving these equations was used to analyze the transport pattern discrepancy in the presence and absence of sediment and the influence of the partition coefficient of pollutants ( K D ). The results show a significant trend of decreased pollutant concentration and corresponding increases in transport age,which indicates that sediment plays a role in weakening the dilution and diffusion processes of pollutants. The partition coefficient of pollutants,which is representative of adsorption capability of sediment,has a positive effect on the transport age. This effect tends to decline to zero when a value of 10 3 L /g is achieved for the partition coefficient of pollutants,when the sediment adsorption capacity tends to be saturated.