淤泥质潮滩重金属和溶解性有机质的潮汐变化特征及其环境影响评价  

Tidal Variation Characteristics of Heavy Metals and Dissolved Organic Matter and Environmental Impact in a Silt Tidal Flat

作　　者：张丽聪 肖凯 张鹏 李海龙 王俊坚 李镇扬 王芬芳 徐华林[4] 郭跃华 ZHANG Licong;XIAO Kai;ZHANG Peng;LI Hailong;WANG Junjian;LI Zhenyang;WANG Fangfang;XU Hualin;GUO Yuehua(School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,P.R.China;School of Water Resources and Environment,China University of Geosciences(Beijing),Beijing 100083,P.R.China;Xiamen University,College of Environmental and Ecological,Xiamen 361102,P.R.China;Administration of Futian Nature Reserve of Neilingding Island,Shenzhen 518040,P.R.China;CCCC-FHEC Ecological Engineering Co.Ltd.,Shenzhen 518107,P.R.China)

机构地区：[1]南方科技大学环境科学与工程学院,广东深圳518055 [2]中国地质大学(北京)水资源与环境学院,北京100083 [3]厦门大学环境与生态学院,福建厦门361102 [4]广东内伶仃福田国家级自然保护区管理局,广东深圳518040 [5]广东省中交一航局生态工程有限公司,广东深圳518107

出　　处：《生态环境学报》2022年第11期2169-2179,共11页Ecology and Environmental Sciences

基　　金：国家自然科学基金项目(42177046;41972260);深圳市科技计划资助项目(JSGG20210802153535002)。

摘　　要：淤泥质潮滩是连接陆地和海洋生态系统的过渡带,也是海陆污染物交换的高频地带。为了解淤泥质潮滩地表水和地下水中重金属和溶解性有机质(DOM)在潮汐作用下的变化特征及环境效应,以漳江口自然保护区的淤泥质潮滩为研究场地,在一个潮汐周期内连续监测了浅层地下水动态、地表水和地下水中理化参数、重金属质量浓度和DOM光谱特征参数的时间变化特征。结合广义达西定律和Fick第一定律定量估算了重金属和有机质的向海排泄通量,最后评估了地下水和地表水中重金属污染的潜在风险。主要结论如下:(1)相比于地表水,地下水中DOM的芳香性和分子量更高,并且对pH和DO的变化更敏感。受上游淡水输入和地下水排泄的影响,潮沟地表水中重金属和DOM质量浓度均与潮汐水位相反,即在低潮期间质量浓度达到最大值,并随着潮位的增加而减少。(2)通过地表水-地下水对流作用携带的重金属和DOM通量是扩散通量的20—200倍。7种重金属在沉积物-水界面的对流通量大小顺序为:Ba(155.00μg·m^(−2)·d^(−1),单位下同)>Zn(36.60)>As(2.00)>Cu(0.33)>Cr(0.32)>Pb(0.21)>Hg(0.19),DOM的对流通量为2.57 mg·m^(−2)·d^(−1)。研究区所在潮滩水动力交换条件差,地表水-地下水交换未能很大程度上改变地下水的缺氧环境,导致污染物滞留在潮滩中。(3)重金属污染评价结果表明,地表水中的Hg处于中度污染水平,而地下水中的As和Hg处于轻度污染水平,其余重金属均处于清洁水平。该研究结果可为漳江口自然保护区中光滩重金属的污染防治提供科学依据。Tidal flat is the transition zone connecting terrestrial and marine ecosystems,and also acts as the high frequency zone of pollutant exchange.In order to understand the variation characteristics and environment effects of heavy metals and dissolved organic matter(DOM)in surface water and groundwater in a silt tidal flat in Zhangjiang Estuary,we monitored the temporal dynamics of shallow groundwater,physicochemical parameters,mass concentration of heavy metals and the spectral characteristic parameters of DOM in surface water and groundwater during a tidal cycle.Combining with the generalized Darcy’s Law and Fick’s First Law,we quantitatively estimated the discharge fluxes of heavy metals and DOM to the sea.We also assessed the potential pollution risk of heavy metals in groundwater and surface water.The results showed that(1)comparing with surface water,DOM in groundwater was characterized by higher aromatic degree and molecular weight,and was more sensitive to the changes of pH and DO.The change trends of heavy metals and DOM in surface water were opposite to the tidal level due to the input of upstream tidal flesh water and groundwater discharge,that is,their concentrations reached the maximum during low tides and decreased with the increase of tidal level.(2)The fluxes of heavy metals and DOM carried by advective flow were 20‒200 times higher than those through the diffusion transport across the sediment-water interface.The order of the advective fluxes of the seven heavy metals was Ba(155.00μg·m^(−2)·d^(−1),the unit was the same below)>Zn(36.60)>As(2.00)>Cu(0.33)>Cr(0.32)>Pb(0.21)>Hg(0.19),and the advective fluxes of DOM was 2.57 mg·m^(−2)·d^(−1).The hydrodynamic condition in the study site was relatively poor,and thus the surface water-groundwater exchange did not change the anoxic environment of groundwater to a great extent,resulting in the retention of pollutants in the tidal flat.(3)The pollution assessment of heavy metals revealed that Hg in surface water was at moderate pollution lev

关 键 词：重金属 有机质 潮滩 地下水 漳江口 

分 类 号：X52[环境科学与工程—环境工程] X53X820.3