不同处理方法对降水中污染元素来源评估的不确定性讨论--以西藏拉萨和纳木错为例  

Uncertainties in the valuation of the sources of polluted elements in precipitation treated by different methods: A case study at Lhasa and Nam Co,Tibet

作　　者：韩小文 陈鹏飞 康世昌 严芳萍[5] 胡召富 高少鹏 李潮流[1,4] HAN Xiaowen;CHEN Pengfei;KANG Shichang;YAN Fangping;HU Zhaofu;GAO Shaopeng;LI Chaoliu(Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing,100101 ,China;State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China;Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli, 50130, Finland;CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China;University of Chinese Academy of Sciences, Beijing, 100049, China)

机构地区：[1]中国科学院青藏高原研究所青藏高原地表过程与环境变化重点实验室,北京100101 [2]中国科学院大学,北京100049 [3]中国科学院西北生态环境资源研究院冰冻圈科学国家重点实验室,兰州730000 [4]中国科学院青藏高原地球科学卓越创新中心,北京100101 [5]芬兰拉彭兰塔理工大学绿色化学实验室,米凯利50130

出　　处：《环境化学》2018年第1期19-24,共6页Environmental Chemistry

基　　金：国家自然科学基金(41675130,41630754)资助.

摘　　要：在降水元素测试中对降水样品的前处理通常有两种方法:样品直接酸化和过滤后酸化.不同的处理方法会得到不同的结果,并最终影响到对元素来源的解释.为明确这两种处理方法对降水中重金属元素来源评估的影响,本文选取青藏高原的典型城市拉萨市和典型的背景区纳木错,对采集的24个降水样品用上述两种方法进行处理,并对两组样品中的15种金属元素的含量和富集因子进行了对比.结果表明,两个研究点过滤后样品元素含量都显著低于未过滤样品的元素含量,其中拉萨未过滤降水样品中的常量元素Al和Fe的含量分别比过滤后样品中的含量高约50和20倍,表明降水中的Al和Fe主要以颗粒态存在.相应地,典型污染元素如Cu、Zn和Cd等在两种样品中的含量变化相对较小,表明这些元素在降水中主要以溶解态存在.同样地,纳木错降水样品中元素也存在类似的变化特征.由于上述原因,拉萨和纳木错过滤后的降水样品中大部分元素(如Ni、Zn和Cd)的富集因子值高于未过滤样品中的值.因此,对降水样品过滤会导致一些典型污染元素的富集因子值增高,进而高估人类活动对这些元素的贡献.所以,用未过滤的降水样品进行元素富集因子研究得到的结果会更接近实际情形.In general, two different treatment methods were used in tracing heavy metal elements inprecipitation： acidifying precipitation samples before and after filtration. Consequently, different results will be obtained and ultimately impact the interpretation of elemental sources. To investigate this issue, fifteen elements of 24 precipitation samples collected at Lhasa （a typical urban area） and Nam Co （ a typical background area） of the Tibetan Plateau were analyzed by the above two methods. The results showed that elemental concentrations of the filtered samples were significantly lower than those without filtration. For instance, the concentrations of Al and Fe in the precipitation samples of Lhasa without filtration were 50 and 20 times higher than those of the filtered samples, respectively, reflecting Al and Fe mainly existed in the particle phase. Correspondingly, concentrations of typical polluted elements such as Cu, Zn and Cd in the two sets of precipitation samples were close, indicating these elements mainly existed in the dissolved phase. Similar phenomenon was also found in Nam Co precipitation samples. Because of the above reasons, the enrichment factors of most studied elements （such as Ni, Zn and Cd） of filtered samples were much higher than those without filtration at both studied sites. Therefore, filtered samples will lead to higher enrichment factors of typical polluted elements, resulting in overestimation of the contribution of human activities on these elements. Therefore, it is proposed that more reasonable results can be obtained from samples without filtration than those of filtered ones.

关 键 词：降水 金属元素 富集因子 青藏高原 

分 类 号：X51[环境科学与工程—环境工程]