黄河入海口湿地区底质重金属污染的Pb同位素示踪

Pollutions From Heavy Metals in the Surface Sediments in the Wetland Region of the Yellow River Estuary:Lead Isotopic Tracer

利用等离子体质谱仪(ICP-MS)和多接收同位素质谱仪(HR-MC-ICP-MS)等技术,对黄河入海口湿地区3个典型区(湿地保护区、采油区和河道)表层沉积物进行了系统的重金属微量元素和Pb同位素分析。结果表明,湿地保护区、采油区和黄河河道三个子区域表层沉积物重金属含量依次降低,受粒度控制明显,且符合第一类沉积物质量标准,处于较清洁水平。Pb同位素数据表明,黄河入海口湿地保护区表层沉积物样品207 Pb/206 Pb和208 Pb/206 Pb比值(0.839,2.090)与已发表文献的中国黄土207Pb/206Pb和208 Pb/206 Pb比值(0.841,2.083)接近,表明黄河湿地保护区内表层沉积物中的重金属Pb的主要来源为黄河自然源(黄土)。采油区及河道样品207 Pb/206 Pb,208 Pb/206 Pb比值(0.848,2.100;0.849,2.105)均高于湿地保护区样品,介于黄河悬浮体(0.865,2.131)及中国黄土之间,表明采油区和河道表层沉积中的Pb主要来源于自然源和人类生产活动。

The present study analysed concentrations of heavy metals and Pb isotopic composition of the surface sediments in the wetland of the Yellow River estuary （wetland reserves, oil-well sites and river channels） using inductively coupled plasma-mass spectrometry （ICP-MS） and high-resolution multi-eolleetor inductively coupled plasma-mass spectrometry （HR-MC-ICP-MS）. The results show that the concentrations of heavy metals of the surface sediments take on a decrease trend in wetland reserves, oil-well sites and river channels in sequence, and which are controlled strongly by grain size of the sediment. Except for the heavy metals （Pb, Cr） exhibiting little enrichment, the concentrations of heavy metals （Ni, Cu, Zn and As） of the sediments in these three typical regions are nearly identical to the background values. Pb isotopic compositions show that the ratios of 207pb/206 Pb and 208Pb/206 Pb of surface sediments in the wet- land region of the Yellow River estuary （0. 839,2. 090, respectively） are close to those of the loess （0. 841, 2. 083, respectively）, which indicate that the heavy metal Pb of the sediments in wetland reserve is mainly derived from the nature source （loess）. The ratios of 207Pb/206Pb, 208Pb/206Pb in the sediments of oil-well sites （0. 848, 2. 100, respectively） and river channels （0. 849, 2. 105, respectively） are both higher than those of the wetland reserve, and lie between those of Yellow River suspension （0. 865,2. 131, respectively） and loess, showing that the heavy metal Pb of the sediments in oil-well sites and river ehannels are mainly derived from a mixed source of the nature source and human activities.