Vulnerability of a public supply well in a karstic aquifer to contamination     

Katz BG  McBride WS  Hunt AG  Crandall CA  Metz PA  Eberts SM  Berndt MP 《Ground water》2009,47(3):438-452

To assess the vulnerability of ground water to contamination in the karstic Upper Floridan aquifer (UFA), age-dating tracers and selected anthropogenic and naturally occurring compounds were analyzed in multiple water samples from a public supply well (PSW) near Tampa, Florida. Samples also were collected from 28 monitoring wells in the UFA and the overlying surficial aquifer system (SAS) and intermediate confining unit located within the contributing recharge area to the PSW. Age tracer and geochemical data from the earlier stage of the study (2003 through 2005) were combined with new data (2006) on concentrations of sulfur hexafluoride (SF₆), tritium (³H), and helium-3, which were consistent with binary mixtures of water for the PSW dominated by young water (less than 7 years). Water samples from the SAS also indicated mostly young water (less than 7 years); however, most water samples from monitoring wells in the UFA had lower SF₆ and ³H concentrations than the PSW and SAS, indicating mixtures containing high proportions of older water (more than 60 years). Vulnerability of the PSW to contamination was indicated by predominantly young water and elevated nitrate-N and volatile organic compound concentrations that were similar to those in the SAS. Elevated arsenic (As) concentrations (3 to 19 μg/L) and higher As(V)/As(III) ratios in the PSW than in water from UFA monitoring wells indicate that oxic water from the SAS likely mobilizes As from pyrite in the UFA matrix. Young water found in the PSW also was present in UFA monitoring wells that tap a highly transmissive zone (43- to 53-m depth) in the UFA.  相似文献   

'Our shared responsibility': participation in ecological projects as a means of empowering communities to contribute to coastal management processes     

Evans SM  Gebbels S  Stockill JM 《Marine pollution bulletin》2008,57(1-5):3-7

The objective of this project was to empower people of Blyth Valley in Northumberland (northeast England) to contribute to the management of their coastal heritage. A group of volunteers, the Links Conservation Group, working in collaboration with the environmental managers (Blyth Valley Borough Council), scientists, local specialists and other volunteers, surveyed the biodiversity, social, cultural and industrial history and profiles of the dunes, as well as their perceived value to local residents. The Group used this information to develop management plans for the dunes. The recommendations have contributed to planning processes at three levels: (i) national coastal management plans; (ii) regional plans; and (iii) plans for further action at the local community level.  相似文献   

用水平定向钻进在北极圈内铺设管道     

Bueno  SM 吴光琳 《岩土钻凿工程》2000,(1):8-11

本文详细介绍了在美国阿拉斯加州用非开挖技术,穿越河流铺设４条油管的工程,穿越长度１３０３ｍ,管径５００ｍｍ。文章介绍了在－５０℃的气温下钻进的情况,包括钻孔液成分泥浆马达和导向等问题。  相似文献   

Occurrence of volatile organic compounds (VOCs) in Liverpool Bay, Irish Sea   总被引：4，自引：0，他引：4  

Bravo-Linares CM  Mudge SM  Loyola-Sepulveda RH 《Marine pollution bulletin》2007,54(11):1742-1753

Surface seawater samples were collected in the Irish Sea and Liverpool Bay area from the R.V. Prince Madog during the period of 25-31 of March 2006. VOCs were purged with nitrogen, pre-concentrated on a SPME fibre and analysed immediately on a GC-MS. Target compounds quantified were halogenated (0.2-1400 ng L(-1)), BTEXs and mono-aromatics (1.5-2900 ng L(-1)), aliphatic hydrocarbons and others (0.6-15,800 ng L(-1)). Day and night sampling was performed at a single station and suggested that factors such as sunlight and tide affect the presence of many of these compounds. Sample variability was high due to the variable weather conditions at the station. Poor correlations were found between marine phytopigments and selected VOCs. Principal component analysis (PCA) analysis showed that chlorinated compounds such as 1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethene, tetrachloroethene and carbon tetrachloride, predominantly from anthropogenic sources, originated from the River Mersey. Other brominated and iodinated compounds quantified were more likely to be from biogenic sources including novel marine compounds such as 2-chloropropane, 1-bromoethane and 1-chlorobutane.  相似文献   

水平圆曲线解算的简单计算法     

Ease.  SM 严伯铎 《测绘科技通讯》1995,18(1):30-31,34

当水平圆曲线给定半径和偏转角时，其余的５个曲线元素就可以直接计算，这５个元素切距，外矢矩，弦矩，弦长和曲线长，在一些实际问题中，半径和偏转角是未知的，而为了要放样曲线，就必须要有其它二个元素是已知的，这样有七种情况必须依靠已知的曲线元素来解算，然而，在这些情况中是不能直接进行未知元素的解算，本文提出一处方法，叫做迭代法，来解算各个未知元素，它和牛顿一拉夫逊法不一样，迭代法不要求转换计算，并用对曲线  相似文献   

晚新生代大陆裂谷作用期间前寒武纪火山成因硫化物矿源再活化形成的？…     

Fulp.  MS 程翔 《国外地质与勘测》1991,(3):41-45

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使用非线性地面剖面来估算采场的挖掘体积     

Easa  SM 郑国忠 《北京测绘》1989,(4):40-45

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道路断面转变地段体积计算的平截头棱锥体公式     

Easa  SM 李学逊 《测绘译丛》1992,(2):23-25

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非完整尺截值视距测量模型     

Easa  SM 李学逊 《武测译文》1992,(1):44-48,41

在视距测量中，当视线较长、竖直角过大以及视线受阻时，常有必要观测1／2或1／4尺截值。此时若采用两倍1／2尺截值或四倍1／4尺截值的标准视距公式来计算水平距离和高差，则会产生相当大的偏差。本文导出了修正后的视距计算公式，该公式为实测1／2或1／4尺截值、竖直角以及有关仪器参数的显函数。这个公式是依据实际完整尺截值与实测部分尺截值之间的几何关系而得出的。非完整尺截值可以在下1／2或上1／2尺截值，或者是下、中下、中上或、1／4尺截值。这个仅对标准视距公式作局部改进的公式，可以很方便地供人工计算或在可编程序计算器上使用。  相似文献   

用交叉线细分四边形的土地面积     

Easa  SM 程翔 《国外地质与勘测》1990,(4):56-64

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