海州湾潮滩重金属污染的历史记录

近岸海域是区域源汇过程的汇,记载了区域环境演变的重要信息.2010年在海州湾潮滩采集得到4个沉积物柱样,对沉积物柱样进行了重金属元素测定,结合核素210Pb测年结果,研究了海州湾潮滩重金属污染历史及人类活动对其影响.运用Al元素作为粒度的代用指标对重金属进行标准化,并获取了重金属富集系数和人为污染的重金属通量.研究表明,粒度控制效应并不是影响海州湾潮滩地区重金属分布的最主要因素,并且各重金属元素之间具有良好的相关性,说明该区域重金属元素具有来源一致性;海州湾潮滩沉积物中除重金属Cr和Cu表现为弱富集外,其他重金属元素Cd、Cr、Cu、Mn、Pb和Zn均表现为强富集,并且表层沉积物中重金属含量均高于该区域的背景值,这表明近50年以来,海州湾潮滩已明显受到人类污染源的影响,从而造成沉积物中重金属不断富集累积;自20世纪50年代至2000年初海州湾潮滩沉积物中人为污染活动输入的重金属通量呈现出波动增加的趋势,这种变化特征与区域社会、经济发展阶段相吻合;而从2005年以来随着区域产业结构优化调整,环境监管力度加强,潮滩沉积物中人为来源的重金属通量呈现出减少的趋势.

History of Heavy Metal Pollution from Tidal Flat in Haizhou Bay

Coastal zone could be considered as an important sink of regional source to sink and preserve historical records of environmental evolution. Four sediment cores, collected from tidal flat at Haizhou Bay near Lianyungang City, were examined for concentrations of heavy metals including Cd, Cr, Cu, Mn, Pb and Zn in core sediments to investigate the historical input of trace metals. In addition, sediment rates of cores LH3 and LH4 were determined based on radionuclide ²¹⁰ Pb. The results showed that grain size control effect was not the main factor that influenced the distribution of heavy metals. Heavy metals concentrations in the surface sediments were higher than these regional background values. Furthermore, Al element as a proxy of grain size was selected for normalization and calculation of metal enrichment factor (EF) and anthropogenic heavy metal fluxes. The results revealed that heavy metals in tidal flats were continuously enriched in the past decades, meanwhile, tidal flats have been significantly subjected to contaminations due to anthropogenic activities. Moreover, the depth profiles of heavy metals fluxes correspond to scenario of social-economy development of Lianyungang, which is an important urban area near Haizhou Bay. From 1950s to 2005, anthropogenic fluxes of metals increased with fluctuations, whereas, since 2005 anthropogenic fluxes declined, which may be correlated to the adjustment of industrial structure as well as the strengthened environmental regulation.