摘要
根据太湖地区1/4°×1/6°经纬度网格的地表特征及α-HCH施用量,建立了一个基于同精度网格系统,包含迁移和传输2个模块的质量平衡模型.迁移模块使用逸度方法描述α-HCH在每一个网格的多介质环境中的迁移过程,传输模块使用拉格朗日方法描述α-HCH在不同网格间的大气平流和水体径流.模型模拟了α-HCH在研究区域开始施用至今(1952～2007年)α-HCH在5类4层土壤、气、水和底泥23个环境相中的积累、迁移和残留情况.模拟值与实测α-HCH浓度对比验证表明两者吻合得很好.环境温度是影响α-HCH在各环境介质中浓度的最重要因素.模拟结果表明,在α-HCH使用时期,在土壤中的年积累趋势约为年使用量趋势的5.7%;在停止使用后,其减少趋势为积累趋势的50%.在α-HCH使用期间,太湖流域α-HCH的年使用量与其水-气界面沉积通量存在显著的相关性,而与土-气界面通量则无显著相关性.α-HCH停止使用后,太湖流域水-气界面通量表现为向大气的挥发,且自1985年其年挥发通量大于土-气挥发通量.底泥是α-HCH水-气界面挥发的主要补给源.2007年太湖流域内α-HCH大气浓度普遍高于流域外大气浓度.整个模拟时段α-HCH的主要输出途径是流出太湖地区,且以大气平流为主;其次的减少途径是在环境介质中的降解,其中土壤降解量占绝大部分.2007年环境中残留的α-HCH为总使用量的0.005%,以土壤残留量为主,其次是底泥.
A mass balance model,including transfer and transport modules,was developed to investigate the long-term fate of α-HCH （hexachlorocyclohexane） in the Taihu Lake region at 1/4° by 1/6° latitude/longitude resolution. The transfer module describes the change of α-HCH concentrations and inter-compartmental transfer of the pesticide in a multimedia environment using a level-IV fugacity method in each grid cell. The transport module calculates the mass exchange of α-HCH driven by winds between grid cells using a Lagrangian method,and pesticide transport due to water currents. Using annual gridded usage inventories of α-HCH from 1952 to 1984 （the year HCH was banned） as input data,the model simulated accumulation,transport,transfer,and fate of α-HCH in 23 compartments including 5 types of soils,air,water,and sediment in Taihu lake from 1952 to 2007. The modeled results match well with measured concentrations in soils,air,water and sediment in Taihu Lake in the 1980s and 2000s. Ambient temperature was the most important factor influencing α-HCH concentrations in all compartments of the lake. From 1952 to 1984,5.7% of α-HCH usage accumulated in soils in the region,50% of which disappeared due to volatilization,degradation,and other processes from 1985 to 2007. Correlations are strong between annual usage and air-water gas exchange flux of α-HCH （r= 0.95,p〈 0.0001,n= 33）,but no significant correlation between annual usage and air-soil exchange flux in the Taihu Lake basin was observed between 1952 and 1984. After the ban of technical HCH use in 1984,the air-water gas exchange was dominated by volatilization from water to air,and this flux has been larger than the soil-air exchange flux since 1985. Residues of α-HCH in the sediment have been an important source for volatilization from water to air. In 2007,higher atmospheric α-HCH concentration was found in the northern and eastern area of Taihu Lake. The mass balance results revealed that outflow （atmospheric advection and water current） was the largest α-HCH loss pathway （55.5% of total α-HCH usage）,followed by degradation in the compartments （44.4% of α-HCH total usage）,in which the degradation in soil was the major portion （97.3% of total degraded amount of α-HCH in all compartments）. The total residue of α-HCH in 2007 was 0.005% of the total used in the model domain,mainly in soil followed by sediment.
出处
《环境科学学报》
CAS
CSCD
北大核心
2009年第10期2180-2194,共15页
Acta Scientiae Circumstantiae
基金
城市水资源与水环境国家重点实验室自主课题项目(No.2008DX01)~~
