1950年以来BHC在杭州环境中积累、迁移与残留动态的模拟研究

Simulating of the accumulation, transfer and fate of BHC since 1950s in Hangzhou, China

根据区域环境背景值、BHC施用量及其物化性质参数 ,以逸度模型为工具 ,建立了描述BHC在杭州多介质环境中迁移转化的动态模型 .通过模拟结果了解各时期BHC在气、水、土壤、沉积物、鱼、植物叶和根等 10种环境介质中的积累、迁移和残留情况 ,并考虑了环境介质物理性质差异、温度对BHC热力学参数的影响 ,及对其环境行为和归宿的影响 .模型模拟了自 195 2年BHC在研究区域大量施用以来 ,在环境中逐渐累积并达到稳定 ,因BHC禁用又逐渐消失的过程中 ,BHC在各环境介质中的分布、浓度及其在毗邻介质间迁移通量的动态变化 .对模拟结果与实测BHC浓度的验证表明二者吻合较好 .虽然杭州地区有机氯农药用量远高于其它地区 ,但由于该区温度较高有利于BHC的降解和挥发 ,目前BHC的浓度和残留量均低于北方地区 .该研究的成果可用于有机污染物暴露风险评价 。

A dynamic fugacity model was applied to simulate the transfer and fate of BHC in Hangzhou according to the physic-chemical properties of the studied area environment and BHC isomers. The simulating results would be helpful to learn about the accumulation, distribution, and transfer and transformation of BHC in the multimedia environment, which was composed of air, water, soil, sediment, aquatic, foliage and roots of terrestrial plant. The impact of regional various of soil compartments and the temperature on the behavior and fate of BHC were considered in the model. Simulating results suggested that excessive agricultural application of BHC had resulted in serious environmental pollution in Hangzhou since early 1950s, and reached its highest concentrations before 1972 and continued to 1983, when the production and application of BHC was prohibited. During this period, about 717t BHC existed in all compartments and nearly 87% existed in the soil compartments. The most important transfer processes were deposition flux from air to soil (91.7t·a^(-1)) and diffusion flux from soil to air (63.8t·a^(-1)), and the other fluxes were all less than 18t·a^(-1). The calculated concentrations of BHC agreed well with the observed ones.The prohibition of BHC application caused quickly decrease of BHC concentrations and fluxes in 1984. A decrease of 98%, 60%, 44%, 90%, 44%, 54% and 40%～90% happened to the BHC concentrations in air, water, dry farmland soil, paddy soil, uncultivated soil, sediment and biota compartments till 1985. The predicted concentrations suggested that in 2020 they would descend to 0.001%～0.088% of the highest concentrations before 1983. Though large amount of BHC had entered the Hangzhou environment, higher atmospheric temperature was favorable for BHC degradation and volatilization, so the residual of BHC in Hangzhou was much lower than the northern cities in China. Results of this study provided the data for risk assessment and this model also provided basic data and framework for simulating environmental behavior and fate of other POPs.