Fractionation,distribution and transport of mercury in rivers and tributaries around Wanshan Hg mining district,Guizhou Province,Southwestern China: Part 2 – Methylmercury

Water samples were collected during normal flow (2007) and during a drought period (2008) from five rivers and tributaries draining the Wanshan Hg mining district, Guizhou, China. Unfiltered methylmercury (MeHg) as well as particulate and dissolved fractions of MeHg (P-MeHg, D-MeHg) were measured to assess the spatial and temporal variation of MeHg contamination in the local river system. Most locations (about 80%) displayed higher MeHg concentrations during drought period than during normal discharge conditions. Concentrations of MeHg during the drought period ranged from <0.035 to 11 ng L⁻¹ (geometric mean: 0.43), while during normal flow the concentrations ranged from <0.035 to only 3.4 ng L⁻¹ (geometric mean: 0.21). Concentrations of MeHg were positively correlated with total Hg (THg) concentrations (R² = 0.20–0.58, P < 0.001) and inversely related to distance from the calcines, during both sampling periods (R² = 0.34 and 0.23, P < 0.001, for low and normal flow, respectively) indicating that calcines may be important sources of MeHg to the downstream environment. Approximately 39% of MeHg was bound to particulates and the rest was transported in the dissolved phase along stretches of the entire river, which was different from THg, as this was mainly transported bound to particulates (commonly more than 80%).     

贵州省金沙煤田龙潭组岩煤层测井对比方法

龙潭组是金沙井田的主要含煤地层，含煤达12~15层，其中7、8、9、11、12五层煤较稳定，为主要可采煤层。根据测井物性曲线与地质岩心的对比分析，总结出该组煤岩层的共有测井物性规律：低密度、中低电阻率、较高中子孔隙度和较低的纵波速度，以及其特有规律如：5、6、7、8、9煤层的低自然伽马，11、12煤层较高的自然伽马等特征。结合煤层测井曲线形态特征及其与顶、底板以及和煤层上、下标志层间组合关系，进行了全煤系地层的对比，揭示了该井田煤层的分岔、合并、冲刷、沉缺、煤层厚度等变化规律。     

Exchange flux of total gaseous mercury between air and natural water surfaces in summer season

The exchanges of mercury between surface and air are of significance in the biogeochemical cycling of Hg in the environment, but there are still few reliable data on air/surface exchange in aquatic systems. Field measurement campaigns over seawater surface at Kristineberg Marine Research Station (KMRS) and over Hovg?rds?n River surface at Knobesholm in southwestern Sweden were conducted to measure mercury flux using a dynamic flux chamber technique coupled with automatic mercury vapor-phase analyzers. Both sites show net emissions during summer time. Mercury fluxes measured over both river and seawater surfaces exhibit a consistently diurnal pattern with maximum fluxes during the daytime period and minimum fluxes during the nighttime period. At freshwater site, mercury flux is strongly correlated with the intensity of net solar radiation, and negatively correlated with relative humidity. A typical exponential relationship between mercury flux and water temperature was observed at freshwater measurement site. At seawater site, a strong correlation between mercury flux and intensity of solar radiation was obtained. The driving force of mercury emission from water surface to air is the super-saturation of dissolved gaseous mercury in aqueous phase.     

Seasonal distribution of total mercury and methylmercury in sediments of the Wujiangdu Reservoir, Guizhou, China

The concentrations of total mercury and methylmercury in sediments were determined at the dam of the Wujiangdu Reservoir in different seasons. Total mercury (HgT) levels in the whole sediment profile were 254.2±47.0 ng/g in winter, 254.2±31.6 ng/g in spring, and 256.7±60.8 ng/g in summer, without significant variations in different seasons or at different depths. In contrast, the methylmercury (MeHg) compounds were most abundant at the sediment-water interface and decreased progressively with depth. MeHg contents of the sediments during different seasons are highly dependent on microbial activity, and seem to be higher when Hg (II)-methylating microorganisms are active. Thus, MeHg levels tend to rise in the loci where nutrient supplies and biological productivity are favorable. The percentage of HgT that is present as MeHg in the sediments increased gradually from December 2003 to April 2004 and to July 2004.     

Chemical characterization and sources of PM2.5 at 12-h resolution in Guiyang,China

The increasing emission of primary and gaseous precursors of secondarily formed atmospheric particulate matter due to continuing industrial development and urbanization are leading to an increased public awareness of environmental issues and human health risks in China. As part of a pilot study, 12-h integrated fine fraction particulate matter (PM_2.5) filter samples were collected to chemically characterize and investigate the sources of ambient particulate matter in Guiyang City, Guizhou Province, southwestern China. Results showed that the 12-h integrated PM_2.5 concentrations exhibited a daytime average of 51 ± 22 µg m^?3 (mean ± standard deviation) with a range of 17–128 µg m^?3 and a nighttime average of 55 ± 32 µg m^?3 with a range of 4–186 µg m^?3. The 24-h integrated PM_2.5 concentrations varied from 15 to 157 µg m^?3, with a mean value of 53 ± 25 µg m^?3, which exceeded the 24-h PM_2.5 standard of 35 µg m^?3 set by USEPA, but was below the standard of 75 µg m^?3, set by China Ministry of Environmental Protection. Energy-dispersive X-ray fluorescence spectrometry (XRF) was applied to determine PM_2.5 chemical element concentrations. The order of concentrations of heavy metals in PM_2.5 were iron (Fe) > zinc (Zn) > manganese (Mn) > lead (Pb) > arsenic (As) > chromium (Cr). The total concentration of 18 chemical elements was 13 ± 2 µg m^?3, accounting for 25% in PM_2.5, which is comparable to other major cities in China, but much higher than cities outside of China.     

寒区大坝心墙土料冬季冻融与防控监测

两河口水电站是雅砻江干流规划开发中的中游控制性龙头电站,大坝为300米级砾石土心墙堆石坝。由于地处川西高原气候区,冬季气候寒冷干燥,大坝心墙土料填筑过程中面临着冻融问题的困扰。基于一个完整冬季的现场监测,系统分析了这一寒区大坝心墙建筑过程中砾石土、接触黏土土料温度变化规律、冻融特征与影响因素以及现有保温措施防冻效果。结果表明,无保温措施条件下,砾石土、接触黏土均出现了负温冻结现象,其中砾石土最大冻结深度达20 cm,接触黏土达14 cm,土料冻结持续时间不超过1个昼夜,为短时冻土。土料降温冻结过程以与外界大气对流换热过程为主,受气温、风速条件影响显著,波动范围较大,而升温融化过程以太阳辐射增温过程为主,与有效辐射起始时间密切相关,因此波动范围较小。监测期内,采用三布两膜保温材料覆盖可有效防止心墙土料冻结的发生,有、无保温材料覆盖条件下浅层土料最低温度可相差约5℃。结合监测结果和现场实际,建议将现有心墙防渗土料半幅填筑方式转换为全幅填筑,并研发轻质、憎水保温材料及其快速收放机械设备,以提高填筑作业进度、强化防冻效果。系统完整的现场实测结果,可为未来寒区水电大坝建设提供基础数据和参考。     

新疆湿地资源时空变化特征及其原因分析研究

以新疆第一次（2000年）和第二次（2011年）湿地资源调查中相同的347块湿地为研究对象,利用3S技术,对CBERS、SPOT5和LandsatTM遥感数据进行调查监测,并结合野外实地验证,比较分析新疆湿地资源的时空变化状况及其原因。结果表明,新疆湿地总面积呈减少的趋势,其中河流湿地和沼泽湿地面积增加,分别增加29162 hm²和17130 hm²,湖泊湿地和人工湿地面积减少,分别减少126618 hm²和19391 hm²;各湿地型中,永久性河流、草本沼泽、森林沼泽和季节性咸水沼泽面积有所增加,洪泛平原、内陆盐沼、永久性 淡水湖、季节性淡水湖、季节性咸水湖和库塘湿地面积减少。新疆湿地面积总变化率-7%,各湿地类型中,面积变化率最大的是湖泊湿地（18%）,呈减少趋势;最小的是沼泽湿地（5%）,呈增加趋势。湿地面积变化的主要原因是气候变化和人类活动。     

基于遥感技术的兖济滕矿区采煤沉陷区现状及动态变化特征

利用遥感技术,对兖济滕矿区2000-2010年的采煤沉陷区动态变化进行了研究,结果表明,2010年,兖济滕矿区累计沉陷面积为88．43km^2,占整个矿区面积的3．53％。10年来,沉陷区面积呈直线上升趋势,由2000年的57．37km^2,增加到2010年的88．43km^2,平均年增沉陷地面积约为3．45km^2。采用遥感手段,在大范围内,可以较直观、准确地确定采煤沉陷区的范围、面积、形态、动态变化等特征,可为沉陷区的综合治理提供科学依据。     

KARST峰丛地貌煤层地温等值线绘制新方法初探

黔西北某井田KARST地貌煤层底板温度受岩溶、沉积环境、构造、水文地质条件等因素的影响，存在无规律变化现象。因此在计算未测地温值时，首先将9煤层底板深度、温度、标高进行多元线性回归分析，利用多元同归关系式计算钻孔地温值，与实测值一起进行线性插值，绘制9煤层底板地温等值线图，并圈出正常温度及一、二级高温范围。