Mercury flows in large-scale gold production and implications for Hg pollution control

Large-scale gold production(LSGP) is one of the five convention-related atmospheric mercury(Hg) emission sources in the Minamata Convention on Mercury. However, field experiments on Hg flows of the whole process of LSGP are limited. To identify the atmospheric Hg emission points and understand Hg emission characteristics of LSGP, Hg flows in two gold smelters were studied. Overall atmospheric Hg emissions accounted for 10%–17% of total Hg outputs and the Hg emission factors for all processes were 7.6–9.6 kg/ton. There were three dominant atmospheric Hg emission points in the studied gold smelters, including the exhaust gas of the roasting process, exhaust gas from the environmental fog collection stack and exhaust gas from the converter of the refining process. Atmospheric Hg emissions from the roasting process only accounted for 16%–29% of total emissions and the rest were emitted from the refining process. The overall Hg speciation profile(gaseous elemental Hg/gaseous oxidized Hg/particulate-bound Hg) for LSGP was 34.1/57.1/8.8. The dominant Hg output byproducts included waste acid, sulfuric acid and cyanide leaching residue. Total Hg outputs from these three byproducts were 80% in smelter A and 84% in smelter B. Our study indicated that previous atmospheric Hg emissions from large-scale gold production might have been overestimated.Hg emission control in LSGP is not especially urgent in China compared to other significant emission sources(e.g., cement plants). Instead, LSGP is a potential Hg release source due to the high Hg output proportions to acid and sludge.     

某些芳香化合物生物降解性研究

研究了５类３２种芳香化合物生物降解性，选用城市污水场污泥富集的混合菌种做菌源，在好氧生物解实验条件下，苯甲酸类、苯酚类和甲苯是较容易降解的；苯和苯的同系物是可生物降解的；苯磺酸类和含氮芳氮芳香化合物均是难降解的。     

环境经济系统分类及协调发展判据研究

应用系统论对环境经济系统进行结构分析,并根据内部相互作用强弱对环境经济系统进行了分类;建立了环境经济协调发展判据,对区域环境经济协调发展问题进行了定量研究。     

Effects of metal cations on sorption-desorption of p-nitrophenol onto wheat ash

The mutual e ects of metal cations (Cu2+, Pb2+, Zn2+, and Cd2+) and p-nitrophenol (NP) on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2+, Pb2+, and Zn2+ diminished the adsorption and increased the desorption of NP remarkably, while Cd2+ had no such e ect. In contrast, NP diminished the adsorption of Cu2+, Pb2+, and Zn2+ onto ash, however, this suppression e ect depended on the initial concentrations of metal cations. NP had no e ect on Cd2+ adsorption on ash. Fourier transform infrared (FT-IR) and X-ray absorption spectroscopic (XAS) studies suggested the following mechanisms responsible for the metal suppression e ect on NP adsorption: (1) large hydrated Cu2+, Pb2+, and Zn2+ shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; (2) Cu2+, Pb2+, and Zn2+ may block the micropores of ash, resulting in decreased adsorption of NP; (3) complexation of Cu2+, Pb2+, and Zn2+ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a “soft acid”, Cd2+ is less e cient in the complexation of oxygencontaining acid groups than Cu2+, Pb2+, and Zn2+. Thus, Cd2+ had no e ect on the adsorption of NP on wheat ash.     

青岛地区边界层特征及酸雨成因

青岛地区边界层风场与温度场垂直分布很特殊，在１５００ｍ高度以下风场，近地面层风速较小，３００—４００ｍ高度风速较大，５００ｍ以上风速减小，１０００ｍ以上又逐渐增大．温度层结早晚稳定，午后２００ｍ以下不稳定，混合层不高，一般在４００ｍ左右，有时可达７００ｍ，低空经常出现多层逆温．冬季盛行偏北风，夏季盛行偏南风，并经常受江淮气旋和黄淮气旋影响，气旋经过青岛地区时，流场经常出现上、下辐合气流．引入平直和上、下切变两种气流，应用平流扩散方程，对青岛地区连续点源所排放的污染物作模式计算，结果表明，在单一平直气流时，污染物传输较远，但浓度轴线也在一定距离上与地面相交．尤其是在雨天，污染物只在局地散布，浓度较大．当风向出现上、下层切变时，污染物传输范围受限制，这些污染物质在雨天经过化学变化即在近距离形成酸雨．     

郑州市环境空气污染变化规律研究

文章对河南省郑州市大气中的四种污染物臭氧、二氧化氮、一氧化碳和PM2.5的时间变化规律进行了分析,并初步探讨了日变化、年变化规律及其影响因素.臭氧呈现出单峰型变化规律,NO2、CO及PM2.5近似为双峰双谷型.年变化规律表现为单峰型,臭氧浓度在夏季达到最大值,冬季达到最低值,而其余三种污染物在冬季浓度达到最高值,在夏季浓度达到最低值.     

江汉平原生态环境的保护和发展

本文探讨了江汉平原生态环境保护和发展的主导思想。作者强调该问题应从更高层次和更大范围来考虑,并在经济和社会发展中做好生态环境的保护工作。持续性生态系统的研究是重要的,要结合人类生存和发展考虑生态环境战略;分析了这一地区的农业资源发展、水利及农村能源等的优势及问题,并提出在改革开放新形势下生态环境的保护和发展建议。     

中国饮用水中多环芳烃的分布和健康风险评价

饮用水中存在的多环芳烃对人类的身体健康会产生危害。应用固相萃取富集法和气相色谱?质谱联用(GC/MS)分析方法对全国主要城市的80座自来水厂出水中多环芳烃的浓度进行了分析。结果表明:各自来水厂的出水中多环芳烃总量在174.02-658.44ng.L-1之间,其中致癌性多环芳烃的总量为55.08-173.36ng.L-1,致癌性多环芳烃占多环芳烃总量比例最高可达到49.68%。就其组成而言,出水中多环芳烃以3环芳烃(31%-37%)为主,但各环均有检出;通过评价水体健康风险,得到水厂出水中多环芳烃对人体的健康风险值是10-6a-1。     

城市回用水中多环芳烃致癌风险评价

为评价人群暴露于城市回用水中16种多环芳烃(polycyclic aromatic hydrocarbons,PAHs)对于人体健康的潜在风险,采用气相色谱-质谱(GC-MS)联用的分析化学方法对不同季节回用水中16种PAHs进行定量分析;在此基础上采用美国国家科学院和国家研究委员会提出的环境健康风险评价方法,分析不同回用条件下具有中国水体基质特色的城市回用水中PAHs健康风险.结果显示,回用水样中16种PAHs的总浓度为1 422.85 ng·L-1,污水处理厂二级出水水样16种PAHs的总浓度为1 791.77 ng ·L-1,经过处理后回用水中PAHs含量有所降低.风险评价分析结果显示,回用水在城市绿化、农业灌溉和景观娱乐3种不同回用途径下多环芳烃的致癌风险分别为788×10-8、2.77×10-6、3.04×10-6,总致癌风险为5.89×10-6.以上结果可以得出,回用水在城市绿化、农田灌溉和景观娱乐接触过程中多环芳烃所增加的致癌风险很低,回用水中多环芳烃的健康风险处于可接受水平.