渤海湾海岸带铂、钯、铑的地球化学特征及环境指示意义

Vehicle exhaust removal systems are the most important contributor for platinum (Pt), palladium (Pd) and rhodium (Rh) in environment from anthropogenic origin. Under the general trend of people's enhanced awareness on environmental protection, many countries have adopted a series of measures to reduce the environmental emissions of traditional heavy metals such as cadmium, mercury, lead, whereas the nessesary information about the biogeochemical behaviors, environmetal pollution status and risks of Pt, Pd and Rh is far from sufficient, and there is no related polices which have been made to control their emission. Coastal zone is the most important seafood breeding sites. It is also an important sink of a variety of pollutants produced by human activities. The biogeochemical behaviors of these pollutants in coastal zone and the harm they do to marine organisms are well related to food safety and human health.It has been generally assumed that anthropogenic PGEs behave in an inert manner and the potential risks associated with environmental exposures to PGEs are minimal. However, many recent studies on PGEs ecotoxicity and bioavailability indicate that these metals may indeed pose certain negative environmental problems, providing some new evidence for their environmental risk assessments. This proposal aims to solve three scientific questions: 1) the concentrations and distribution characteristics of Pt, Pd and Rh in coastal water of Bohai Bay and the environmental factors influencing them; 2) the contents, distributions and historical variations of Pt, Pd and Rh in coastal sediments of Bohai Bay and the environmental factors influencing them; 3) distinguishing the anthropogenic and natural origins of Pt, Pd and Rh in the research area.To February 2012, the number of vehicles in Beijing and Tianjin has been over seven million, and such a large number of vehicles will inevitably lead to a considerable part of Pt, Pd and Rh being transported into the Bohai Sea through various approaches. To carry out this research in coastal Bohai Bay will do much help to understanding the biogeochemical behaviors of these elements and their influence on coastal ecosystem with continuous increase in concentration.

车辆尾气净化系统是环境中人为输入的铂（Pt）、钯(Pd)、铑(Rh)最主要的来源。随着人们环保意识的加强，各国采取了一系列措施减少镉、汞、铅等传统重金属的环境排放，但对新型重金属污染物Pt、Pd、Rh的生物地球化学行为、环境污染情况和危害缺乏必要了解，且没有控制措施。海岸带是人类活动产生的各种污染物的重要汇区，有必要了解新型重金属Pt、Pd、Rh污染物在海岸带的生物地球化学行为。本项目旨在解决三个问题：1)渤海湾海岸带水体中Pt、Pd、Rh的浓度和分布特征及影响因素；2)渤海湾海岸带沉积物中Pt、Pd、Rh的含量、分布、历史变化及影响因素；3）研究区域人为来源与自然来源Pt、Pd、Rh的区分。至2012年2月北京和天津的机动车保有量已超过700万辆，必然会导致相当部分Pt、Pd、Rh通过各种途径进入渤海，在渤海湾海岸带地区开展本研究有助于了解这些元素的持续增加对海岸带生态系统的影响。

人类活动来源的铂族元素在环境中积累所带来的风险越来越受到人们重视。但其在海水中的生物地球化学行为如：海水、沉积物中的含量、时空分布以及与相关地球化学背景参数的关系等，却一直受限于这类元素的超低含量的影响。本项目针对海水中铂族元素的富集检测、含量分布与相关生态环境因子的耦合关系，以及不同生态环境因子对铂族元素在海水中的迁移转化等问题进行了深入的研究。首先，我们研究了海水中铂族元素的富集方法，包括液-液萃取和固-液萃取两种。建立得到了一种利用稳定的商用树脂PA1，高效富集（富集倍数可达到200倍）海水中铂族元素的固-液萃取方法；利用螯合剂2-MBT对铂族元素的选择性吸附，得到了一种高效的液-液萃取方法。项目首次得到了渤海海域海水以及沉积物中铂族元素的含量和时空分布，并分析了这些元素的分布特征。通过实验室模拟研究了铂族元素与海洋中悬浮颗粒物和胶体有机质之间的作用发现：铂族元素更倾向于吸附在矿物类颗粒物上，其次是粘土颗粒物和生源颗粒物；有机质的存在阻碍了铂族元素在颗粒物上的分配。另外实验室还模拟研究了铂族元素在海水中不同粒径的胶体有机质中的分配，初步得到了铂族元素在海水-有机质之间的分配规律。Pt主要在1 kDa~3 kDa分子量的胶体有机质中分配。Pd倾向于与<1 kDa分子量的有机物络合，Rh则更倾向于1 kDa~3 kDa的有机质结合。并且在天然有机质中的分配，Rh可以与多组分有机质作用，Pd则与腐殖酸有关，Pt则与腐殖酸和蛋白类化合物有关。