State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, PR China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China.
Chemosphere. 2017 Oct;185:717-725. doi: 10.1016/j.chemosphere.2017.07.075. Epub 2017 Jul 17.
The partitioning of ten heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn) between the water, suspended particulate matter (SPM), and sediments in seven channel sections during three hydrologic seasons in the Yangtze Estuary was comprehensively investigated. Special attention was paid to the role of tides, influential factors (concentrations of SPM and dissolved organic carbon, and particle size), and heavy metal speciation. The SPM-water and sediment-water partition coefficients (K) of the heavy metals exhibited similar changes along the channel sections, though the former were larger throughout the estuary. Because of the higher salinity, the K values of most of the metals were higher in the north branch than in the south branch. The K values of Cd, Co, and As generally decreased from the wet season to the dry season. Both the diagonal line method and paired samples t-test showed that no specific phase transfer of heavy metals existed during the flood and ebb tides, but the sediment-water K was more concentrated for the diagonal line method, owing to the relatively smaller tidal influences on the sediment. The partition coefficients (especially the K for SPM-water) had negative correlations with the dissolved organic carbon (DOC) but positive correlations were noted with the particle size for most of the heavy metals in sediment. Two types of significant correlations were observed between K and metal speciation (i.e., exchangeable, carbonate, reducible, organic, and residual fractions), which can be used to identify the dominant phase-partition mechanisms (e.g., adsorption or desorption) of heavy metals.
在长江河口的七个河道断面，于三个水文季节调查了十种重金属（砷、镉、钴、铬、铜、汞、镍、铅、锑和锌）在水相、悬浮颗粒物（SPM）和沉积物相之间的分配。特别关注了潮汐的作用、影响因素（SPM 和溶解有机碳的浓度、颗粒大小）以及重金属形态。尽管重金属的 SPM-水和沉积物-水分配系数（K）在整个河口均较大，但它们沿河道断面的变化趋势相似。由于盐度较高，大多数金属的 K 值在北支比南支高。镉、钴和砷的 K 值通常从湿季到干季逐渐降低。对角线法和配对样本 t 检验均表明，在涨潮和落潮期间，重金属没有特定的相转移，但由于潮汐对沉积物的影响相对较小，所以对角线法的沉积物-水 K 值更集中。分配系数（特别是 SPM-水的 K 值）与溶解有机碳（DOC）呈负相关，但与沉积物中大多数重金属的颗粒大小呈正相关。K 值与金属形态（即可交换态、碳酸盐态、还原态、有机态和残渣态）之间存在两种类型的显著相关性，这可以用来确定重金属的主要相分配机制（例如，吸附或解吸）。
