利用升尺度建模方法研究持久性有机污染物在长江口水体中的归趋

Modeling is an important method to study the fate of pollutants in water. But the mismatch between model parameters and measured values at sampling points results in the problem of scale discrimination, increasing the systematic error in the modeling process and reduces the accuracy of the simulation results. This study plans to deal with the scale problem solution through space -liter model grid scale and the scale of the measured values, deriving parameter represents the value of the model grid scales, and thus obtain the spatial distribution of the study area parameter values. On the basis of studies on the Yangtze Estuary, the study has been carried out on sampling at the profiles in the estuary, and set up a cell in the experimental section of each profile. The adsorption equilibrium of organic pollutants in the water and the degradation kinetics determined by sampling the measured values Estimating Model grid scale distribution coefficient , the degradation rate and other parameters to achieve upscaling transformed; reuse Yangtze Delta dimensional hydrodynamic simulation results, the projected distribution coefficient without measured values of the grid, the degradation rate and other parameters, and the measured value to the entire study area promotion, establishment of Yangtze Delta typical fate of POPs model to study the migration and transformation of pollutants. Upscaling of the study design modeling approach can be more scientific and rational choice of model parameters, reducing systematic errors in the modeling process, to further improve the accuracy of model simulations.

模型模拟是研究水体中污染物归趋的重要手段。但是模型网格参数与采样点实测值存在着尺度不匹配的问题，造成了建模过程中的系统误差，降低了模拟结果的准确性。本研究拟通过空间升尺度方法解决模型网格尺度和实测值尺度的不匹配问题,推求模型网格尺度上的参数代表值，进而获得研究区参数值的空间分布。在课题组已开展的关于长江口水环境研究的基础上，本研究拟在长江口设置采样断面和实验小区，测定有机污染物在水体中的吸附平衡和降解动力学，由采样测定值推求模型网格尺度上的分配系数、降解速率等参数，实现升尺度转化；再利用长江口三维水动力学模拟结果，推算无实测值网格的分配系数、降解速率等参数，实现实测值向整个研究区的推广，建立长江口典型持久性污染物归趋模型，研究污染物迁移转化规律。本研究设计的升尺度建模方法可以更为科学、合理地选择模型参数，减小建模过程中的系统误差，进一步提高模型模拟的准确性。

本研究在对长江口典型持久性有机污染物时空分布规律分析的过程中，建立了大尺度模型（实测值总体数学模型）和小尺度模型（三维水动力水质模型），描述了有机氯农药为代表的持久性有机污染物的迁移转化规律和主要影响因素。基于长江口三维水动力学模型为基础，利用本研究建立的污染物迁移模型，进行了污染物浓度变化模拟结果与水动力学条件等影响因素间的相关性分析，通过污染物迁移与水动力学条件、水质的回归分析，分析了污染物在水、大气、悬浮颗粒物、底泥直接的分配和迁移，分析了水动力学因素对污染物迁移的作用机理。结合水动力学条件、气象条件、区域地理特征、潮汐和洋流等因素的季节性变化，分析了以六六六为代表的有机氯农药类持久性有机污染物在长江口的迁移转化规律。通过不同尺度模型的模拟比对，提高了水中污染物归趋模拟分析的准确性，和影响因素分析的可信性。