长江三峡水库诱发地震地下水动态监测井网建设

着重对长江三峡工程诱发地震地下水动态监测井网的建设过程、成果以及井网试运行与考核运行的情况进行了介绍 ,并对井网的观测数据进行了内在质量分析与评价。结果表明 ,井网数据具有较高的内在质量 ,不仅可为一定震级以上的水库诱发地震趋势预测提供地下水前兆依据 ,而且还可为水库诱发地震研究提供有价值的研究和参考资料.     

盾构掘进引起地表沉降的多因素敏感性分析

为了研究各因素在盾构法施工中对地表沉降的影响程度,基于敏感性分析原理,针对一地铁盾构实例,选取土体弹性模量、土仓压力、地下水等3个影响地表沉降的因素,通过变化某一基准参数,让其余影响因素固定,分析研究了盾构施工引起地表沉降对各因素的敏感性。结果如下:弹性模量提高10%时,地表累积最大沉降量可减小15%～20%;在地下水存在的情况下,地表沉降显著增大;而对于砂性土而言,土仓压力越高地表沉降值略有增加。研究结果表明:地表沉降对穿越地层的弹性模量和地下水比较敏感,而对土仓压力敏感性较小。     

Catalytic Oxidation of Indigo Carmine in the Presence of Silver Nanoparticles: Application to Groundwater Analysis

The oxidation of indigo carmine by potassium hexacyanoferrate(III) is catalyzed by trace of silver nanoparticle (AgNP). The reaction is followed UV‐Vis absorption spectrophotometrically by measuring the change in the absorption spectra (λ_max 612 nm). The catalytic oxidation reaction is used for the quantification of indigo carmine. The calibration graph was linear in the concentration range 50 nM—1.8 μM of indigo carmine. The variables affecting the method have been optimized. The method is applied to the determination of indigo carmine in groundwater samples with the satisfactory results.     

Determination of volatile organic hydrocarbons in water samples by solid-phase dynamic extraction

In the present study a headspace solid-phase dynamic extraction method coupled to gas chromatography–mass spectrometry (HS-SPDE-GC/MS) for the trace determination of volatile halogenated hydrocarbons and benzene from groundwater samples was developed and evaluated. As target compounds, benzene as well as 11 chlorinated and brominated hydrocarbons (vinyl chloride, dichloromethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, carbon tetrachloride, chloroform, trichloroethylene, tetrachloroethylene, bromoform) of environmental and toxicological concern were included in this study. The analytes were extracted using a SPDE needle device, coated with a poly(dimethylsiloxane) with 10% embedded activated carbon phase (50-μm film thickness and 56-mm film length) and were analyzed by GC/MS in full-scan mode. Parameters that affect the extraction yield such as extraction and desorption temperature, salting-out, extraction and desorption flow rate, extraction volume and desorption volume, the number of extraction cycles, and the pre-desorption time have been evaluated and optimized. The linearity of the HS-SPDE-GC/MS method was established over several orders of magnitude. Method detection limits (MDLs) for the compounds investigated ranged between 12 ng/L for cis-dichloroethylene and trans-dichloroethylene and 870 ng/L for vinyl chloride. The method was thoroughly validated, and the precision at two concentration levels (0.1 mg/L and a concentration 5 times above the MDL) was between 3.1 and 16% for the analytes investigated. SPDE provides high sensitivity, short sample preparation and extraction times and a high sample throughput because of full automation. Finally, the applicability to real environmental samples is shown exemplarily for various groundwater samples from a former waste-oil recycling facility. Groundwater from the site showed a complex contamination with chlorinated volatile organic compounds and aromatic hydrocarbons. Figure SPDE Principle     

Snow gauge undercatch and its effect on the hydrogen and oxygen stable isotopic composition of precipitation

ABSTRACT

We investigated the influence of post-collection changes and snow gauge undercatch on the stable isotopic compositions of winter precipitation. Post-collection changes by evaporation or sublimation can be severe, and may be minimized, but not eliminated, by emptying collection gauges immediately after snowfall. Snow gauge undercatch caused two main effects: a small direct effect caused by preferential separation of snow particles during snowfall, and a much larger effect on the measured stable isotopic compositions of average annual precipitation as a result of under representation of winter precipitation. Despite these effects, however, we found little change to calculated local meteoric water lines (LMWL) for Saskatoon, SK, Canada. A comprehensive 27-year LMWL for Saskatoon which incorporates these effects can be described by δ²H?=?7.69?±?0.096?×?δ¹⁸O?–?2.22?±?1.72 (r²?=?0.97, n?=?208).     

Carbon isotopic analyses for source apportionment studies of the greenhouse gases carbon dioxide and methane

We investigated the environmental water sources used in mid-summer by three Sonoran Desert phreatophytic riparian tree species, Salix gooddingii, Populus fremontii, and the exotic Tamarix spp., at sites that differed in water table depth. Salix gooddingii was most sensitive to water table decline, as evidenced by lower predawn water potentials. Although P. fremontii was less sensitive to water table decline than S. gooddingii, its leaf gas exchange was the most responsive to atmospheric water stress imposed by high leaf-to-air vapor pressure deficit. Tamarix spp. was least sensitive to water table decline and showed no reduction of predawn water potential over the measured range of depth to groundwater. Comparison between D/H of xylem and sampled environmental water sources suggest that S. gooddingii and P. fremontii used groundwater at most sites with no change in water source as depth to groundwater varied. In contrast, xylem D/H of Tamarix spp. was depleted in deuterium compared to groundwater at most sites, suggesting use of water from an unsampled source, or discrimination against deuterium during water uptake. This study highlights the difficulty in sampling all water sources in large-scale studies of riparian ecosystems with complex subsurface hydrogeology.     

Anomalous fluoride concentration in groundwater—is it natural or pollution? A stable isotope approach

Fluoride anomalies (up to 11 mg/l) have been detected in groundwater of the central region of Rio Grande do Sul State, Southern Brazil, in an area where fluorosis is endemic. Two hypotheses are investigated concerning the fluoride origin: lithochemical affiliation from regional rock or contamination by fertilisers application. These hypotheses are discussed based on the stable isotope data of water, nitrate, and sulphate, which indicates that the local precipitation is the main groundwater recharge source. The isotopic composition of groundwater sulphate is similar to that of fertiliser sulphate. However, a conclusive assignment of groundwater sulphate to fertiliser origin is not indicated because further possible sulphate sources fall into the same isotopic range. In contrast, the isotopic composition of dissolved nitrate suggests that there is no direct relationship to the use of NPK fertilisers. Hence, an origin of the high fluoride content in groundwater related to long-term rock–water interactions seems likely.     

闭路循环动态针捕集-气相色谱法分析地下水中的硝基苯和苯胺

动态针捕集(Needle trap,NT)是一种集采样、提取、浓缩、进样于一体的免溶剂分析技术,适于痕量有机目标组分的采样分析.本研究通过对比6种采样技术,研究了基于超声的闭路循环动态顶空-NT分析地下水中的硝基苯及苯胺的方法,确定了NT对地下水目标物顶空采样的最佳条件;通过对比GC普通分流/不分流进样口和一种多模式OPTIC2进样口,优化NT的解吸条件,得出的OPTIC2进样口对目标物响应值高且峰形尖锐.填充一层吸附剂的NT对目标物的残留低于0.79％,苯胺的检出限为2.9～3.7μg/L,硝基苯的检出限为0.7～1.9 μg/L.苯胺和硝基苯的回收率在83％～113％之间.     

Groundwater Quality at the Huaibei Coalfield,China

The environmental and health impacts of trace elements are of great concern because of their toxicity, persistence, and bioavailability. Twenty-six groundwater samples were collected from the coal mining areas to evaluate water quality and potential environmental impact caused by mining activities. The physical/chemical properties and trace element concentrations (As, Cd, Cr, Cu, Pb, and Zn) were determined. The physical/chemical parameters and the concentrations of trace elements varied among the shallow and confined groundwater, which may indicate the absence of hydraulic interactions between the aquifers. The concentrations of trace elements in the mining areas are higher than at background monitoring sites, which suggests that the mining activities may lead to environmental and health impacts. Based on a health risk assessment, the low hazard quotients and cancer risk values in confined groundwater samples indicate that the chronic and cancer adverse effects due to trace elements are negligible. This study provides a comprehensive assessment of groundwater trace element impacts from coal mining in China and is useful for environmental management.     

Intercomparison measurements of Rn concentration in water samples in Poland

The paper presents the results of intercalibration measurements of ²²²Rn concentration in water samples. The aim of the experiments was to evaluate the different measurement methods of radon determination in water samples performed by eleven laboratories in Poland and to test these methods in field work. In the years 2001-2003 three national intercomparison experiments were organized. The results allowed the participating laboratories to improve their measurement methodologies and to achieve better, i.e. more convergent results of determining radon concentration in water samples. The results show that the use of liquid-scintillation technique seems to be the best measurement method. It should be emphasized that comparative experiments are essential for all laboratories and they should be carried out as often as possible, based both on prepared samples with known concentration values of ²²²Rn and natural water samples, the most commonly used in laboratory practice.