北方典型农居环境空气中颗粒态汞的污染特征

Characteristics of Particulate Mercury in Typical Rural Household of Northern China

近年来,我国农村环境问题日渐凸显,重金属污染是其中的一个重要方面。以往研究对于农居环境中的重金属污染状况关注很少,造成相关基础信息的缺失。以重要的重金属污染物——汞为研究对象,采集了我国北方3省夏季农户室内外空气和不同家用燃料排放的PM10样品,采用冷原子荧光法测定其中的颗粒态汞含量。结果表明,农户室内外空气中颗粒态汞浓度范围在27.6-727.2p^g/m3,平均为139.4 pg/m^3,高于国外乡村大气,但低于国内城市大气。室内空气中颗粒态汞的浓度受当地生活习惯和燃料类型的显著影响。不同燃料燃烧排放颗粒态汞的能力不同,从大到小依次为树根〉煤球〉树枝〉煤气〉作物秸秆。研究还发现,农作物不同部位燃烧排放颗粒态汞的能力差别很大;煤球充分燃烧时的排放显著高于焖烧时。对北方农居环境空气中颗粒态汞的健康风险进行了初步评价,结果表明成年人每周吸入的颗粒态汞占每周可耐受剂量的0.015%,对健康造成的风险较小,北方农村地区的汞污染防治可重点关注农业生产和乡镇企业排放等其他方面。

Environmental problems especially the heavy metal pollution was becoming increasingly serious in rural China.Particulate matter with an aerodynamic diameter less than 10 μm（PM10） samples were collected in Liaoning,Shandong and Hebei Province.Particulate mercury（pHg） was analyzed with cold atomic fluorescent mercury tester.The mercury concentration in PM10 was between 27.6 and 727.2 pg/m^3 and the mean value was 139.4 pg/m^3,which was higher than that in rural areas aboard but much lower than that in urban China.The pHg concentration while cooking in rural areas approximated that of urban areas in winter.Progressively higher mercury emissions resulted from combustion of straw,natural gas,branches,coal,roots.The content of pHg under complete combustion was 2.18 times of that under incomplete combustion.However,the health risk from fuel combustion was not very severe because of short exposure time.The exposure level to particulate mercury was far less than the minimum level from World Health Organization（WHO）.The weekly intake of pHg per adult was 763.9 pg/（kg·w） which accounts for 0.015% of Provisional Tolerable Weekly Intake.The mercury pollution from daily life was not so serious at rural areas that the government should pay more attention to other aspects,like biomass burning in field,industry pollution.