Large-scale mercury variations in Lake Vänern (Sweden) 1974-98

Lake V?nern, the largest lake in Sweden, has been seriously contaminated with mercury during the 20th century. In the 1970's and 80's the direct load, mainly from a chlor-alkali industry in the area, of mercury was drastically reduced as a response to new legislation, from three to five tons down to between five and ten kg yr(-1). Large amounts of the disposed pollutant have accumulated in the sediments. The question posed in this work is now, is the effect of the drastic load reduction after more than two decades visible in the sediments? The question is relevant as large areas still are blacklisted for fishing, but also as a follow-up of a major remedy action. The lake also serves as a freshwater reservoir for even Sweden's second largest city. This work synthesises and compares data of mercury in the sediments from three major field programs, in 1974, 1984 and 1998. The interest is focused on both spatial heterogeneity and temporal trends. In 1974, the surface concentrations are significantly higher than in subsequent surveys. Significant differences are also found between 1984 and 1998. Significant spatial differences within the lake are found for respective year. The most contaminated area is located in the north, close to the major point source (a former chlor-alkali industry). This is also the area with the largest improvement, as a direct response to the reduction in load. Further from the outlet, the recovery is more affected by burial and transport processes out into the deeper basins.     

Parameters Influencing Sediments Resuspension and the Link to Sorption of Inorganic Compounds

In the aquatic environment, the accumulation of chemicalcontaminants by sediments poses a potential threat to endemiclife forms and drinking water resources. Trace metals such asCd, Cu, Cr, Ni, Pb, and toxic organic compounds, are among awide variety of contaminants having an affinity for sediments.In this study, experiments were performed simulating sedimentresuspension in the lower Housatonic River, Connecticut, using aParticle Entrainment Simulator. Analyses of grain sizedistributions, porosities and total organic contents of thesediments suggested that these parameters influence theredistribution and entrainment of settleable solids in the watercolumn. These findings were established by evaluating the impactof one parameter on sediment resuspension as a function ofstream flow with the other two characteristics being heldconstant. Total suspended solids and volatile suspended solidsresuspension concentration ranged from 3.2 to 20648.3 mg L^-1,and 1.5 to 1823.8 mg L^-1, respectively, with subsequentincreases in flow rates from 9 to 6 dynes cm^-2. The resuspension concentrations were augmentedby sediment porosity (22.0 to 57.5%), percent finer grain-size distributions at 0.1 mm, and total organic content (2.7 g kg^-1 to 29.0 g kg^-1). Using K _p values, and the dissolvedcontaminant levels of various trace metals, the particulatecontaminant levels of the metals were determined under variousoscillation rates. As sediment resuspension increased withincreased stream flow, there was an overall general increasefrom 0.02 to 33.6 g L^-1 in the particulatecontaminant levels of Cd, Cu, Cr, Ni and Pb.     

博乐市空气质量变化趋势分析

分析了博乐市2001-2005年空气质量监测数据在不同月份、不同年份、不同污染因子的变化趋势，并结合当地能源结构、地理位置、气候特征、城市环境综合发展水平。指出影响博乐市空气质量的主要因素，为防治或减轻博乐地区的空气污染提供了科学依据。     

泰州市环境空气中挥发性有机物分布特征

于2018年4—9月对泰州市环境空气中挥发性有机物(VOCs)组分开展现场观测,结合观测数据分析该市大气中VOCs的时空分布特征。结果表明:观测期间泰州市环境空气中VOCs平均摩尔比为45.1 nmol/mol,其中含氧挥发性有机物占比为57.8%;受周边排放源和地理位置影响,下风向点位的VOCs测定值高于其他点位;VOCs月均最高值出现在6月,与臭氧月均最高值出现时间一致,7—9月气团出现老化,导致臭氧生成能力减弱;观测期间VOCs中甲苯/苯(T/B)比值范围为0.201 9～5.130 3,且大部分T/B比值2,说明溶剂、油气和液化石油气挥发等排放源对泰州市环境空气中VOCs的影响较为显著。     

灰色模型在确定关键污染因子中的应用

将灰色模型引入水环境质量评价中 ,通过对某个时间段内污染物原始监测数据的灰色处理 ,从动态演变中找出关键因子 ,客观地判定各污染因子所起的作用 ,并对各因子在下一个时间段的发展趋势作出判断 ,增加了评价的准确性。经过实例运用分析表明 ,该方法物理意义明确 ,简便易用     

入海河流对近岸海域海湾影响分析

利用污染指数法及相关系数法对盘锦市境内的河、海水质进行对比分析，从而得出近岸海域海湾水质主要受入海河流水质影响的结论。     

中国黄土元素背景值分异规律研究

报道了中国黄土中40个元素的背景值,并以F、Cr、Mn、Co、Ni、V、Cu、Zn、As、Se、Cd、Pb、Hg等13个元素为例,讨论了其在黄土高原的分布与含量。利用趋势面分析等数理统计方法,揭示了黄土中元素的某些环境地球化学特征及元素背景值的分异规律。结果表明,黄土的元素背景值具有三维的分异特征,黄土的质地及沉积的生物气候环境黄土是影响背景值分异的主要因素。为中国黄土的风成学说提供了佐证。     

福建省森林固定CO2价值评估

借鉴国内外研究成果,引入“市场逼近系数”,构造森林固定CO2效益经济结构模型,评估福建省森林固定CO2价值,为福建省森林资源的科学管理和资产评估提供了借鉴和参考。     

排放系数法估算污染物排放总量

掌握污染物总量动态变化情况，采用排放系统法进行估算是有效的方法。利用１９９５年上海乡镇工业污染调查数据对排放系数进行验证，说明应如何选用排放系数。     

曲面零件在拉深过程中内皱时刻及影响因素

进一步推导了曲面零件悬空区上的应力分布及临界失稳公式。然后通过计算机编程 ,求解了临界失稳方程 ,得到了拉深系数、相对锥顶半径、相对圆角半径、材料相对厚度与临界失稳时刻间的关系曲线 ,并对曲线变化的规律进行了分析。