Impacts of gold mine waste disposal on deepwater fish in a pristine tropical marine system

Little is known about the impacts of mine waste disposal, including deep-sea tailings, on tropical marine environments and this study presents the first account of this impact on deepwater fish communities. The Lihir gold mine in Papua New Guinea has deposited both excavated overburden and processed tailings slurry into the coastal environment since 1997. The abundances of fish species and trace metal concentrations in their tissues were compared between sites adjacent to and away from the mine. In this study (1999-2002), 975 fish of 98 species were caught. Significantly fewer fish were caught close to the mine than in neighbouring regions; the highest numbers were in regions distant from the mine. The catch rates of nine of the 17 most abundant species were lowest, and in three species were highest, close to the mine. There appears to be limited contamination in fish tissues caused by trace metals disposed as mine waste. Although arsenic (several species) and mercury (one species) were found in concentrations above Australian food standards. However, as in the baseline (pre-mine) sampling, it appears they are accumulating these metals mostly from naturally-occurring sources rather than the mine waste.     

我国非开挖行业现状与展望

概述了常用的各类非开挖施工技术方法及非开挖施工的主要优势;介绍了我国非开挖行业的3个发展阶段,目前的发展现状,以及存在的主要问题;对我国非开挖技术的市场前景进行了分析判断。     

一种等高线地图编辑的机助几何设计方法

等高线图是表达三维数据的简便方法。尽管它不能显示直观的三维图像但在实际工作中仍被广泛地应用着。人工描绘等高线或采集散数据是非常枯燥而烦琐的。因此，若能够将电子计算机处理的等高线图的数据储存起来，将是十分有益。一幅等高线地图在计算机中通常是以一组多边形存贮的。     

Simulating ground water-lake interactions: approaches and insights

Approaches for modeling lake-ground water interactions have evolved significantly from early simulations that used fixed lake stages specified as constant head to sophisticated LAK packages for MODFLOW. Although model input can be complex, the LAK package capabilities and output are superior to methods that rely on a fixed lake stage and compare well to other simple methods where lake stage can be calculated. Regardless of the approach, guidelines presented here for model grid size, location of three-dimensional flow, and extent of vertical capture can facilitate the construction of appropriately detailed models that simulate important lake-ground water interactions without adding unnecessary complexity. In addition to MODFLOW approaches, lake simulation has been formulated in terms of analytic elements. The analytic element lake package had acceptable agreement with a published LAKI problem, even though there were differences in the total lake conductance and number of layers used in the two models. The grid size used in the original LAKI problem, however, violated a grid size guideline presented in this paper. Grid sensitivity analyses demonstrated that an appreciable discrepancy in the distribution of stream and lake flux was related to the large grid size used in the original LAKI problem. This artifact is expected regardless of MODFLOW LAK package used. When the grid size was reduced, a finite-difference formulation approached the analytic element results. These insights and guidelines can help ensure that the proper lake simulation tool is being selected and applied.     

水平定向钻进技术在环境治理中的应用

人口、资源和环境问题是全球二十一世纪共同面临的三大难题，也是社会、经济可持续发展的三大要素。本文简要介绍水平定向钻进技术在环境治理中的应用，包括水平环境治理井的设计和施工方法。最后，以问答的形式回答几个大家所关心的问题。希望本文能起到专引玉的作用，并对有关人员在今后进行环境治理时有所启发。