【作者】 丁小勇；

【导师】 张卫东； 陈来国；

【作者基本信息】 西南大学 ， 环境科学， 2010， 硕士

【摘要】 汞是一种非生命必需元素,可通过呼吸、皮肤吸收、饮食等途径进入人体,危害人类健康。无机汞可以通过甲基化作用生成毒性很强的甲基汞。自日本发生水俣病(Minamata Disease)事件以来,汞污染一直引起全球持续关注。最近几十年,化石燃料燃烧、金属冶炼和工业生产等人为活动不断向环境释放大量的汞,导致区域性的汞污染不断加剧,汞也被公认为“全球性污染物”。汞可在大气-土壤-水体间交换,土壤和沉积物不仅是环境介质间汞交换的重要源和汇,而且是汞甲基化的重要场所,因此对土壤与沉积物中汞的研究具有重要意义。燃料燃烧、垃圾焚烧、水泥和陶瓷工业、氯碱工业、电池生产等涉汞行业是人为汞污染的重要来源。珠三角地区经济发达,其GDP占全国总量的约10%,且仍以每年约15%的速度增长,能源消耗总量大且将进一步增加,垃圾焚烧厂家数量占全国总数的约1／4,陶瓷产量占全国的约1／2,涉汞行业多且数量大,导致其环境中可能有较高含量的汞,同时珠三角地区独特的亚热带气候特点也有利于汞在不同环境介质间的迁移转化。北江是珠江流域第二大水系,是沿线的韶关、清远、肇庆和佛山等城市的主要饮用水源地,流域内工业污染源和矿区较多,且有电子垃圾拆解基地,汞是环境中重要特征污染物之一为了解珠三角地区土壤与北江沉积物汞污染现状,评价其污染程度,探索汞转化为甲基汞的影响因素,于2009年4～9月采集了珠三角地区741个土壤样品和北江19个沉积物样品,测定了样品中总汞(THg)和甲基汞(MeHg)含量,并分析了THg、MeHg与土壤pH、有机质(OM)的相关性,本研究初步获得以下结论：1、珠三角地区表层土壤THg含量范围为16.72～3 324.41 ng·g-1,平均值为278.01 ng·g-1。各城市表层土壤THg含量：佛山>广州>江门>东莞>肇庆>珠海>惠州>中山>深圳,水平分布以佛山、广州两大区域为高汞含量地带；垂直分布从表层至底层THg含量逐级递减,主要在0～40 cm土壤中富集,不同功能区THg含量：城市>农村,公园>生活区>工业区>菜地>稻田>耕地。珠三角地区土壤MeHg含量范围为0.14～1.34 ng·g-1,均值为0.31 ng·g-1,各城市土壤样品MeHg含量均值差距不明显,水平分布没有明显的规律。单因子污染指数法评价结果表明,珠三角地区土壤中THg平均浓度为轻度污染,其中广州、佛山为中度污染,深圳为未污染,其余城市为轻微污染；珠三角地区土壤中MeHg平均浓度为中度污染,其中东莞、惠州、江门为轻度污染,其余城市为中度污染。单因子潜在生态风险评价结果表明,总体上珠三角地区土壤汞属于轻微生态危害程度,其中广州和佛山属于中等生态危害程度,深圳属于微弱的生态危害程度,其余城市为轻微生态危害程度。2、相关性研究表明,研究区域土壤pH值与THg、MeHg含量没有明显的相关性,有机质与THg、MeHg含量显著相关,pH、有机质与汞的甲基化率均没有明显的相关性,表明汞的甲基化是一个复杂的过程,需要在该领域进一步加强研究。3、北江干流与支流沉积物THg含量范围为73.72～3 517.13 ng·g-1,平均浓度为607.62ng·g-1,THg空间分布与距离排污口远近有关,总体上距离越远含量越低,韶关冶炼厂和大宝山矿区为北江THg重要污染点源。北江干流与支流沉积物MeHg含量范围为0.39～2.38ng·g-1,平均浓度为1.30 ng·g-1,空间变化趋势与THg含量的变化趋势不一致。根据单因子污染指数法的评价结果,北江沉积物中THg, MeHg总体均属中度污染,但在部分靠近排放点源的区域污染较为严重。THg潜在生态风险评价结果表明北江沉积物属于强的生态危害程度。4、珠三角地区土壤甲基化比率变化范围为0.003%～1.51%,北江沉积物各采样点汞的甲基化率变化范围为0.024%～1.45%,差异较大,进一步研究汞甲基化的影响因素十分必要。更多还原

【Abstract】 Mercury is a non-essential element which is harmful to human’s health as it could be intook via inhalation, dermal intake and diet, the inorganic could be methylated into methylmercury with high toxicity. After the Minamata Disease happened, mercury pollution has been concerned globally. During the last decades, a great deal of mercury have been discharged into atmosphere by people’s activity such as combustion of fuel, metal smelting and industries. As the mercury pollution is more and more serious, mercury is regarded as "a global pollutant". Mercury could be exchanged among atmosphere, soil and water. Soil and sediment are not only the the important source and sink for mercury exchange, but also a main place for mercury methylation. Hence, it is significant to study mercury pollution in soils and sediments.Combustion of fuel and garbage, industries such as cement, ceramic, chlor-alkali and battery are the main artificial mercury pollution source, Economy of the the Pearl River Delta(PRD) is prosperous, and the GDP contributed about 10% to that in China, with an increasing rate of 15% annually. As the economy is developing, the demand of energy increases as well. A quarter of national garbage combustion plants and a half of ceramic plants were located in the PRD,along with many other mercury relative industries, which leading to potential high levels of mercury in the environment. Furthermore, the subtropical climate in the PRD accelerate the transfer and transformation of of mercury among different environmental media. The Beijiang River is the second branch of the Pearl River, and it is the main water source for Shaoguan, Qingyuan, Zhaoqing and Foshan. Along the Beijiang River, there are many industries, mines, and even e-waste dismantling area. Therefore, mercury may be is an significant pollutant in the Beijiang River area.This article is to study on pollution status and assessment of mercury in soil of the PRD and sediment of the Beijiang River,741 soil samples and 19 sediment samples have been collected in this district from April to September of 2009, content of THg and MeHg has been determinated, correlations between mercury, pH and organic matter have also been analyzed.1.The concentration of THg in surface soil from the PRD ranged from 16.72 to 3324.41 ng-g-1, with an average value of 278.01 ng-g-1.The THg levels in surface soil from different cities decreased as the following order:Foshan>Guangzhou>Jiangmen>Dongguan>Zhaoqing> Zhuhai>Huizhou>Zhongshan>Shenzhen;with Guangzhou and Foshan as the high mercury polluted areas.. The vertial distribution shows that, the THg in soils descended from surface layer to sub-layer, with a mercury pool in the 0-40 cm soil. Distribution of THg in different used type is urban>rural area, Park>Living area>Industry area>Vegetable field>Rice filed>Woodland area,The MeHg in top soil from PRD ranged from 0.14 to 1.34 ng-g-1; with an average value of 0.31 ng-g-1, with no obvious distinction and distribution features for soils in different cities. According to single pollution index (SPI) assessment of THg, generally, PRD is at light polluion level, both Guangzhou and Foshan are at medium polluion level, Shenzhen with no pollution, others are at light pollution level. The SPI assessment of MeHg showed that, generally, PRD is at medium pollution level, Guangzhou, Shenzhen, Foshan, Zhaoqing, Zhuhai, Zhongshan are at medium polluion level, and Dongguan, Huizhou, Jiangmen are at light pollution level. The potential ecological risk assessment of THg showed that, generally, PRD is at light ecological risk, Guangzhou and Foshan are at at medium ecological risk level, Shenzhen is at a low ecological risk index, the others are at light ecological risk level.2. The linearity study showed that, pH value was found to have no obvious correlation with THg or MeHg, and organic matter (OM) was significantly correlated with THg and MeHg. Besides, neither pH value nor OM was significantly correlated with mercury methylation rate, indicating mercury methylation is a complex process, and further studies are required.3.The THg levels in sediment from Beijiang River ranged from 73.72 to 3 517.13 ng-g-1,with an average value of 607.62 ng-g-1. Generally, the THg levels decreased as the sampling sites located further from the drain outlet.Shaoguan smelting factory and Dabaoshan mine are the key piont pollution source of THg for the Beijiang River. The MeHg levels in sediment from the Beijiang River ranged from 0.39 to 2.38 ng-g-1,with an average value of 1.30 ng-g-1,with a different spatial distribution from the THg in this area. The SPI assessment of THg and MeHg showed that, the sediments from the Beijiang River are at medium pollution level, but the sampling sites near the drain outlet are suffering from serious pollution. The potential ecological risk assessment of THg showed that, Beijiang River is at a powerful ecological risk index.4.The methylation rate ranged from 0.003% to 1.51% for soils from the PRD, and from 0.024% to 1.45% for sediments from the Beijiang River, respectively. Totally, the methylation rates varied greatly, All these suggest that further studies investigating the affecting factors of mercury methylation are needed.更多还原