环境中高氯酸盐的自然来源、形成机制及其归趋行为

Natural Origins,Formation Mechanisms,and Fate of Environmental Perchlorate

高氯酸盐(ClO4-)作为新型的环境有毒污染物,其环境污染问题已引起国内外学者的极大关注,但有关ClO4-的自然来源及形成机制的研究则刚刚起步。ClO4-的自然来源、在不同环境介质中的背景浓度及迁移转化行为,对制定ClO4-的环境质量标准和系列安全浓度限值至关重要,但国内相关研究几乎为空白。本文总结了ClO4-在对流层和平流层气溶胶、大气湿沉降(雨和雪)、地下水、海水、土壤及矿物等环境介质中的背景浓度水平,不同环境介质中涉及样品数为气溶胶3个、雨水1 600多个、降雪样品3个、地下水2 100多个、海水2个、土壤(矿物)10多个、火星土壤样品1个;重点评述了自然源ClO4-的前体物质及大气反应形成机制(臭氧氧化、光化学反应和闪电作用),提出ClO2-/ClO2是大气中ClO4-自然形成的关键前体物质;归纳了自然源ClO4-在各环境介质间的迁移转化及归趋行为,最后简单介绍了识别ClO4-自然来源的同位素示踪技术,并展望相关研究。

Perchlorate （ClO4^-） as an emerging trace pollutant, has caused a great concern about its environmental pollution problems. The natural origin of ClO4^- as well as its formation mechanisms is a new research focus. In order to establish new environmental quality standards and safety concentration limits of ClO4^-, it is quite important to recognize its natural origins, background concentrations, transport and fate in various environmental media, but few researches were reported in China. In this paper, the background concentration levels of ClO4^- in tropospheric and stratospheric aerosol, atmospheric wet deposition （rain and snow）, groundwater, seawater, soil and minerals are summarized. The data for ClO4^- concentrations in the aerosol were very limited, such as 0. 5-5 ppt in the stratospheric aerosol, 〈 1.8 ng/m^3 （Japan） and-5.0 ng/m^3 （China） in the tropospheric aerosol. The ClO4^- concentrations in rain were ND--24 400 ng/L for more than 1 600 samples, and 1--18 ng/L in Arctic snow. The ClO4^- concentrations in groundwater were widely inves for China, Germany and India, which were mainly pooled tigated in USA, and recently, some data were reported in 10^-1--10^2 μg/L for more than 2 100 samples. Thereported ClO4^- concentrations in sea water were O. 16----6. 11 μg/L. As a dominant natural origin, the atmospheric reaction mechanisms （i. e. , ozone oxidations, photochemical reactions, and lightning effects） and precursors of ClO4 are highlighted. It is believed that the species of C102-/ C102 is a critical precursor for the formation of natural ClO4^- at the atmosphere. The transport, fate, and biogeochemical cycling of natural ClO4^- in the environments are described in details. The isotope tracer approaches for identification of natural source of ClO4^- are briefly introduced. The research trends and currently existing problems are prospected.