Rare earth element for tracing the source of suspended particulate matter of Lake Chaohu

Abstract

采用化学连续提取和等离子质谱仪(ICP-MS)测定法,对安徽巢湖悬浮颗粒物中稀土元素的含量、赋存形态和配分模式进行了研究.结果表明:巢湖悬浮物中稀土总量在19.20-174.82mg/kg之间,东西两个湖区含量差异明显,东半湖区高于西半湖区.巢湖东西湖区悬浮物残渣态稀土元素具有截然不同的页岩标准化配分模式,东半湖区为轻稀土富集型,西半湖区为重稀土富集型,说明巢湖东西湖区具有明显不同的物质来源.巢湖东半湖区和西半湖区悬浮物稀土元素赋存形态比例也不同,东半湖区为残渣态>铁锰 氧化物结合态>>有机结合态、AEC态;西半湖区为铁锰氧化物结合态>残渣态>>有机结合态、AEC态,这是由于巢湖水体从西到东受到的污染强度减轻造成的,稀土元素赋存形态可以作为判别湖泊污染程度的新依据.;The concentration, speciation and distribution of rare earth elements (REEs) in the suspended particulate matter ( SPM) of Lake Chaohu were studied by inductively coupled plasma mass spectrometry (ICP-MS) after sequential extraction in order to investigate the source of matters in the aquatic environment. The result shows that the total REE concentrations in SPM have a wide range with the value varying between 19. 2-174. 82 mg/kg. These concentrations in the east part of lake were clearly higher than that in the west part of lake. Shale-normalized REEs of residual fraction of SPM show the light REE enrichment pattern in the east part of lake，while it is heavy REE enrichment in the west part of lake. The results indicate that the SPM in the lake Chaohu have different materials source. The solid speciation characteristics of REE in the SPM are also very different from the east part of lake to the west part of lake. The percent of four forms of SPM obey the following order； residual > bound to Fe-Mn oxides >> adsorbed-exchangeable-carbonate (AEC) or bound to organic matter in the east part of lake Chaohu, and Fe-Mn oxides > residual >> AEC or bound to organic matter in the west part of lake Chaohu. It is because the pollution intensity has a decreasing tend from the west part to the east part of the lake. The speciation characteristics of REE in SPM may can as a new indicator of water pollution.