九龙江流域水体沉积物重金属污染的多同位素体系示踪

Jiulong River basin has an importation position in the economic development of China because of its special location. Serious environmental problems, especially heavy metal pollution in sediments, have occurred as the consequence of rapid economic development. However, little work has been done so far to investigate heavy metal pollution in sediments of Jiulong River basin. A systematic study is thus needed to decipher the sources of heavy metals, and to better understand their transformation mechanisms during transport in this basin. This project intends to systematically investigate the heavy metal pollution in sediments of this basin, using the newly developed stable isotope tracing method. Total digestion and extraction isotopic compositions of Pb, Sr, Nd and Cd in sediments and potential sources collected from Jiulong River basin will be analyzed combined with the geochemical characteristics of trace elements. The objectives of this project are: 1) to reveal the source, accumulation and migration of heavy metals in sediments of Jiulong River basin; 2) to establish the isotopic composition dataset of typical pollution sources; 3) identify the emission characteristics and the appropriate environmental effects; 4) to investigate the real contribution of heavy metals from the atmosphere; 5) to better understand the evolution and transformation mechanisms of heavy metals in the river; 6) to quantificationally discriminate the contributions of diversified sources to the heavy metals in Jiulong River sediments using multivariate mixed models of Pb-Sr-Nd-Cd isotopes combined with factor and multiple linear regression analysis. This study will provide an important dataset and valuable information for the prediction and control of heavy metal pollution in Jiulong River basin.

九龙江流域在我国具有特殊的地理位置和经济地位，经济快速发展造成较为严重的水体沉积物重金属污染。该流域水体沉积物重金属污染研究还相当薄弱，对重金属污染源的“家底”认识不清，对重金属排放后的环境效应及在水体沉积物中的迁移转化机理认识十分匮乏。项目以九龙江流域重金属污染为研究对象，采用传统与非传统稳定同位素示踪方法，通过对九龙江流域水体沉积物和潜在污染源的Pb-Sr-Nd-Cd同位素组成及形态中的Pb-Sr-Nd-Cd同位素组成分析，结合微量元素地球化学特征，揭示水体沉积物中重金属污染来源、积累和迁移规律，建立典型污染源同位素组成谱，探索重点污染源排放特征及其环境效应，明确大气沉降对水体沉积物重金属的贡献，分析不同相态同位素组成，运用同位素多元混合模型结合因子-多元线性回归分析精确判别水体沉积物中重金属的主要来源及各污染源的贡献率，阐明重金属在流域水体沉积物中的演变机制.

九龙江流域在我国具有特殊的地理位置和经济地位，经济快速发展造成较为严重的水体沉积物重金属污染。该流域水体沉积物重金属污染研究还相当薄弱，对重金属污染源的“家底”认识不清，对重金属排放后的环境效应以及在水体沉积物中的迁移转化机理认识十分匮乏。项目以九龙江流域、厦门杏林湾近郊流域水体沉积物中重金属污染为研究对象，采用稳定同位素方法，通过对九龙江流域、厦门杏林湾近郊流域水体沉积物和潜在污染源Pb-Sr-Nd同位素组成及形态中的Pb-Sr-Nd同位素组成分析，结合微量元素地球化学特征，揭示水体沉积物中重金属污染来源、积累和迁移规律，建立典型污染源同位素组成谱，运用同位素多元混合模型结合因子-多元线性回归分析精确判别水体沉积物中重金属的主要来源及各污染源对水体沉积物中重金属的贡献率.取得的主要成果：.(1)阐明了九龙江流域水体沉积物、厦门杏林湾近郊流域水体沉积物中重金属及稀土元素空间分布特征和重金属潜在生态风险。.(2)确定了九龙江流域河口水体沉积物中主要重金属元素、稀土元素及Pb、Sr、Nd、同位素自然背景值。.（3）沉积物及潜在污染源铅同位素分析结果表明，沉积物中铅主要来源于土壤母质、燃煤和福建铅锌矿，其相对贡献率分别为34.4%、34.0%和31.6%。稀硝酸提取态铅同位素组成表明稀硝酸提取态铅同位素组成比沉积物总量更能灵敏反映铅的人为源信息。锶同位素分析结果表明，沉积物中锶主要为外来源和自然源，其相对贡献率分别为57.5%和42.5%。.（4）九龙江不同区域沉积物中稀土元素具有相似的地球化学特征。总稀土含量（REEs）和轻重稀土比值（LREE/HREE）较高，且呈现明显Eu负异常说明沉积物主要为陆源。球粒陨石标准化和北美页岩标准化配分模式表明九龙江沉积物物源相似。La-Th-Sc和La/Yb-∑REE图解以及Nd同位素分析结果表明九龙江沉积物主要来源为福建花岗岩风化沉积，同时受到一定程度的人为影响。.(5)项目第一标注成果发表学术论文15篇，参加国际、国内会议11次，培养博士1名、硕士6名。