流域尺度重金属行为模拟及其对不同气象因子的响应特征研究  

Modeling the fate and transport of heavy metals,and their response to climate change at the watershed scale

作　　者：周凌峰 孟耀斌[1,2,3] 逯超[1,2,3] 伍甘霖 张东妮 蒋飞红 ZHOU Ling-feng;MENG Yao-bin;LU Chao;WU Gan-lin;ZHANG Dong-ni;JIANG Fei-hong(Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education, Beijing Normal University, Beijing 100875, Chi?na;Academy of Disaster Reduction and Emergency Management, Ministry of Emergency Management & Ministry of Education, BeijingNormal University, Beijing 100875, China;Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China;Chang?sha Hydrology and Water Resources Survey Bureau of Hunan Province, Changsha 410014, China)

机构地区：[1]北京师范大学环境演变与自然灾害教育部重点实验室,北京100875 [2]北京师范大学应急管理部/教育部减灾与应急管理研究院,北京100875 [3]北京师范大学地理科学学部,北京100875 [4]湖南省长沙水文水资源勘测局,长沙410014

出　　处：《农业环境科学学报》2019年第5期1112-1120,共9页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(41271497);北京师范大学地表过程与资源生态国家重点实验室方向性项目(2017-FX-07)

摘　　要：模拟重金属的流域尺度行为有利于更好地理解重金属对生态系统和人类的潜在不利影响,而探究重金属在不同气象情景下的迁移转化规律有利于流域环境风险分析和环境管理。本研究采用流域重金属迁移转化模型SWAT-HM,该模型考虑了重金属化学反应如吸附和老化反应;陆面重金属迁移过程包括通过水分渗流和蒸发引起的垂向下降上升运动以及通过土壤侵蚀和地表/地下径流的水平迁移;水体中重金属迁移过程包括沉降、再悬浮、扩散和掩埋等过程。本研究选取湖南浏阳河上游流域为研究区,该流域几十年来一直受到采矿活动的影响,重金属污染严重。结果表明,SWAT-HM模型对于流域内重金属锌(Zn)和镉(Cd)的动态模拟结果与监测结果符合较好,94.5%的Zn和94.2%的Cd的模拟浓度与实测浓度在同一数量级内。流域内Zn和Cd的高污染区主要集中在宝山河,当宝山河与大溪河汇合后,由于稀释作用和水沙交互作用,溶解相Zn和Cd浓度显著降低至地表水环境质量Ⅲ类水标准(GB 3838—2002)以下。2009—2014年流域出口Zn和Cd总输出通量的多年均值分别为90.8 t和1.1 t,溶解相重金属和吸附相重金属输出量的大幅提升几乎全部出现在强降水后,吸附相重金属输出量主要由几次暴雨过程贡献。本研究通过气象因子分析方法评价重金属输出量对于降雨和气温变化的敏感性,结果显示溶解相重金属和吸附相重金属输出量对于降雨变化比温度变化敏感,且吸附相重金属对于降雨变化的响应比溶解相重金属强烈。探究不同气象情景下重金属迁移转化响应特征对于环境风险分析和污染控制具有一定意义。Modeling heavy metal behavior in soil and water will provide a better understanding of the potential adverse impacts on human and ecological system. A heavy metal transport and transformation module was combined with the well-established Soil and Water Assessment Tool(SWAT)model to simulate the fate and transport of metals at the watershed scale. The heavy metal module accounts for sorption and slow reactions among categorized metal species. Heavy metal transport in the upland is modeled based on water percolation,rising, runoff, and soil erosion;while in the water body, heavy metal undergoes settling, resuspension, diffusion and burial processes. The SWAT model combined with heavy metal module(SWAT-HM)was used to simulate zinc(Zn)and cadmium(Cd)dynamics in the upper Liuyang River basin. The simulations were reasonably accurate, with 94.5%(Zn)and 94.2%(Cd)of the prediction-to-observation ratio below a factor of 10.It also agreed well with other monitoring data by reproducing the high metal concentrations and their drop before and after the Baoshan-Daxi confluence, and by revealing the dominance of precipitation events in terms of watershed metal exports. To account for the effects of climate change on heavy metal pollution, we also simulated the Zn and Cd output from the studied watershed under nine meteorological scenarios, each with either the temperature or the precipitation intensity adjusted from recorded values. We found that the metals were more sensitive to precipitation than temperature, and that particulate metals responded more strongly than dissolved metals. Our results showed that SWAT-HM is a powerful tool for watershed-scale environmental risk analysis and pollution control in the context of climate change.

关 键 词：流域尺度 重金属行为 模型模拟 情景分析 

分 类 号：X52[环境科学与工程—环境工程]