Assessing groundwater-surface water connectivity using radon and major ions prior to coal seam gas development (Richmond River Catchment,Australia)

Coal seam gas (CSG, or coal bed methane) mining is rapidly growing, with poorly understood impacts on groundwater and surface water systems. Here, we use chemical tracers to investigate groundwater-surface water connectivity in an Australian river system (Richmond River Catchment, New South Wales) prior to CSG extraction but after ∼ 50 exploratory CSG wells were drilled. We performed four surveys of 29 interconnected creek and river sites, over contrasting hydrological conditions. Radon was used to determine if a surface water segment was gaining groundwater. Radon observations over four seasons revealed that 28 out of 77 surface water segments were clearly gaining groundwater, 5 were possibly gaining groundwater and 44 were undetermined. This is equivalent to gaining segments in 333 km (39%) of surface water from the 864 km being investigated. High spatial and temporal variability in groundwater gaining segments was found. Na/Cl ratios were used to determine the fraction of groundwater in surface water. Overall, the groundwater contribution in surface waters was 14–24% higher in post flood conditions than during the other three surveys of baseflow and moderate flow conditions. The results serve as a regional baseline assessment of river water chemistry and groundwater-surface water connectivity prior to the planned development of CSG fields. Our geochemical tracer approach allows for a quick qualitative assessment of groundwater-surface water connectivity in poorly gauged river systems and can define priority locations where groundwater extraction for CSG mining should be carefully managed.     

东乡地区有色、贵金属矿(点)重磁场特征及找矿探讨

东乡地区处赣东北断裂、信江隐伏深断裂相交部位及两侧,地跨两个地体,区内的有色、贵金属矿床大都受断裂作用的控制,与之成矿关系密切的岩体是赛阳关闪长玢岩体.由于断裂带中及两侧分布的不同地层或岩体存在密度差异,导致其上方出现重力梯度带,而重力梯度带及其变异带上分布众多的航磁局部异常,这些局部磁异常是目前全区已知有色、贵金属矿的主要分布地带.结合地质化探资料,掌握重(磁)异常的分布情况时开展矿产勘查及找矿评价有着重要的意义.     

A comparison between heavy metals released from soil and its efficient speciation extracted by sequential extraction procedure

A simulating experiment was carried out on the interaction between natural precipitation and soil. The results demonstrated that the contents of heavy metals （V, Co, Cr, and Ni） released from soil into the solution under Earth＇s surface conditions are higher than the contents of those metals bonded to exchangeable species, which were extracted by sequential extraction procedure recommended by Tessier and others in 1979. It is demonstrated that the metals bonded to other 3 species （carbonate, Fe-Mn oxide, and organic matter） except those bonded to the exchangeable species in efficient speciation can be released under the Earth＇s surface conditions, when pH=4 in the reaction system, and the higher correlation coefficient indicated that the concentrations of heavy metals released from soil into the solution vary approximately with reaction time in terms of index regulations.     

江汉平原大气污染源分析

通过选择不同的环境功能区布置大气干湿沉降样点,分析重金属污染元素和有机氯农药的颗粒态与溶解态指标,计算季沉降通量和年沉降总量,了解其随季节变化的规律,分析比较不同地貌条件、不同城市及不同污染源区对其沉降的源贡献。结果表明:大气对江汉平原重金属的输入途径以降水为主;重金属元素颗粒物在平原区的沉降通量略高于岗丘地区;武汉市高于其他城市;工业污染源区明显高于一般农田区;三类污染源区相比,颗粒态为烟尘>化工尘>交通尘,溶解态为化工尘>交通尘>烟尘(个别元素除外),且大气降水中的营养元素N、K、Fe在化工工业区较为富集,而P的沉降在烟尘和化工工业区则受到一定程度的抑制。两种主要有机氯农药不同异构体间的组分关系表明本区环境中近期仍有林丹输入。     

富镉铅锌矿床开采过程中水质污染特征——以贵州都匀牛角塘富镉锌矿床为例

铅锌矿的开采和选冶使含锌和镉等有害物质的尾矿暴露于地表,这些有毒元素通过自然风化淋滤作用进入地表水,进而污染矿区水体,对矿区生态环境破坏性极大。本文通过对贵州都匀牛角塘富镉锌矿区河流、选矿厂排放的污水、坑道水进行采样分析,发现矿区水体呈弱碱性,水体重金属污染并不严重,其中Cd等重金属有毒元素的含量大多没有超过生活用水国家标准和农业灌溉水国家标准。结合已有研究成果,认为碳酸岩地区碱性环境限制了镉等重金属有毒元素的活化迁移,使其就近富集在矿区土壤、植物及河流沉积物中。更重要的是由于碳酸盐岩对矿山酸性排水的中和缓冲作用,降低了矿石的风化淋滤速度,减轻了因铅锌矿开采和选冶活动导致的Zn、Cd等有毒重金属元素对矿区环境的污染,为非碳酸岩地区铅锌矿山环境污染和治理提供了一些借鉴。     

Assessment of heavy metal contamination in soils around Manali industrial area, Chennai, Southern India

The concentrations of heavy metals (As, Ba, Co, Cr, Cu, Ni, Mo, Pb, Sr, V and Zn) were studied in soils to understand metal contamination due to industrialization and urbanization around Manali industrial area in Chennai, Southern India. This area is affected by the industrial activity and saturated by industries like petrochemicals, refineries, and fertilizers generating hazardous wastes. The contamination of the soils was assessed on the basis of geoaccumulation index, enrichment factor (EF), contamination factor and degree of contamination. Soil samples were collected from the industrial area of Manali from the top 10-cm-layer of the soil. Soil samples were analyzed for heavy metals by using Philips MagiX PRO-2440 Wavelength dispersive X-ray fluorescence spectrometry. The data revealed elevated concentrations of Chromium (149.8–418.0 mg/kg), Copper (22.4–372.0 mg/kg), Nickel (11.8–78.8 mg/kg), Zinc (63.5–213.6 mg/kg) and Molybdenum (2.3–15.3 mg/kg). The concentrations of other elements were similar to the levels in the earth’s crust or pointed to metal depletion in the soil (EF < 1). The high-EFs for some heavy metals obtained in the soil samples show that there is a considerable heavy metal pollution, which could be correlated with the industries in the area. Contamination sites pose significant environmental hazards for terrestrial and aquatic ecosystems. They are important sources of pollution and may result in ecotoxicological effects on terrestrial, groundwater and aquatic ecosystems. In this perspective there is need for a safe dumping of waste disposal in order to minimize environmental pollution.     

Dechlorination of perchloroethylene using zero-valent metal and microbial community

This research evaluates an integrated technique for the degradation of perchloroethylene (PCE) using a combination of zero-valent metal and an anaerobic microbial community. The microbial community was obtained from river sediment through a series of cultivation and enrichment processes, and was able to successfully convert PCE to ethylene. The degradation tests were carried out in five groups of reactors, i.e. Zn (zero-valent zinc), Fe (zero-valent iron), MB (a microbial community), ZnMB (zinc and a microbial community) and FeMB (iron and a microbial community). The results suggested that the FeMB system had the highest efficiency in removing PCE (about 99.9% after 24 days), followed by Zn (98.5%), ZnMB (84.8%), Fe (76.9%) and MB (49.6%). The degradation kinetics of PCE could be described by a pseudo-first-order reaction; the apparent reaction rate constants were 0.231, 0.187, 0.135, 0.076, 0.031 days⁻¹ for the Zn, FeMB, ZnMB, Fe, and MB systems, respectively. Much more Cl⁻ was detected as a by-product in the degradation tests using FeMB or ZnMB than using Fe or Zn. The results implied that not only PCE, but also the reaction intermediates, e.g., trichloroethylene (TCE) and dichloroethylenes (DCE isomers) may have been dechlorinated in the FeMB and ZnMB systems. Results suggest that the presence of the microbial community in the FeMB and ZnMB systems may not only affect the removal efficiency of PCE, but can also change the reaction pathways in the dechlorination process. The integrated technique combining the iron and the microbial community showed better degradation efficiency than the others; it may be viewed as an environmentally desirable remediation.     

Comparison of dissolution under oxic acid drainage conditions for eight sedimentary and hydrothermal pyrite samples

The abiotic oxidative dissolution behaviors of eight natural pyrite samples, five sedimentary and three hydrothermal, from various geological environments were compared under oxic conditions at pH 3 and 6 in a highly controlled batch reactor dissolution system. The three sedimentary pyrite samples associated with coal had greater specific surface areas and also exhibited greater apparent dissolution rates and extent than the other two sedimentary and three hydrothermal samples under both pH conditions. However, after normalizing for surface area, the dissolution rate constants for the different pyrite samples were similar; the greatest difference was between the two non-coal sedimentary pyrite samples. Pyrite morphology and the presence of trace metals could contribute to the differences in dissolution behavior as reflected in the normalized dissolution rates. The sulfur:iron ratio observed in the aqueous solution at pH 3 increased with time, but was always less than 2.0 (predicted from the stoichiometry of dissolution) for all the pyrite samples during the 24-h experimental duration. This can be explained by the disproportionation dissociation of thiosulfate, an initial product of pyrite dissolution, to elemental sulfur and sulfate which does not occur in a 1:1 ratio. The results of this work indicate the importance of extracting and using the specific pyrite(s) relevant to particular mining areas in order to understand pyrite dissolution rates and the influence of environmental conditions on those rates.     

三维前方交会在大型金属网架结构中的应用

探讨了三维前方交会法在大型无支撑金属网架结构屋面施工的质量监测方法,并对实测数据进行了分析,结果表明该方法保证施工质量,达到设计要求,为今后的安全运营提供了可靠的依据。同时为大型无支撑建筑屋顶的变形监测提供了一种测量监测依据。     

Determination of Free Nickel Ion Concentrations Using the Ion Exchange Technique: Application to Aqueous Mining and Municipal Effluents

Free metal ion concentration is generally considered a useful indicator of a metal’s bioavailability and ecotoxicity to aquatic biota. This article reports the speciation of nickel in mining and municipal effluents from Sudbury (Ontario, Canada), and also in model solutions containing a fully characterized laurentian fulvic acid (LFA) at environmentally relevant concentrations. A column ion exchange technique (IET) using a cation exchange resin (Dowex 50W-X8) was applied to determine free nickel ion concentrations. In model solutions, reasonable correlation was found between the predictions of an equilibrium-based computer speciation code, Windermere Humic Aqueous Model (WHAM) VI, and the results obtained by IET at low nickel-to-fulvic acid ratios. However at higher mole ratios, the WHAM VI predicted higher free nickel ion concentrations than IET. Only three out of six effluent samples showed reasonable agreement between the IET and the WHAM VI results, indicating the need for further development of IET for application to effluent waters.