Field verification of stable perched groundwater in layered bedrock uplands

Data substantiating perched conditions in layered bedrock uplands are rare and have not been widely reported. Field observations in layered sedimentary bedrock in southwestern Wisconsin, USA, provide evidence of a stable, laterally extensive perched aquifer. Data from a densely instrumented field site show a perched aquifer in shallow dolomite, underlain by a shale-and-dolomite aquitard approximately 25 m thick, which is in turn underlain by sandstone containing a 30-m-thick unsaturated zone above a regional aquifer. Heads in water supply wells indicate that perched conditions extend at least several kilometers into hillsides, which is consistent with published modeling studies. Observations of unsaturated conditions in the sandstone over a 4-year period, historical development of the perched aquifer, and perennial flow from upland springs emanating from the shallow dolomite suggest that perched groundwater is a stable hydrogeologic feature under current climate conditions. Water-table hydrographs exhibit apparent differences in the amount and timing of recharge to the perched and regional flow systems; steep hydraulic gradients and tritium and chloride concentrations suggest there is limited hydraulic connection between the two. Recognition and characterization of perched flow systems have practical importance because their groundwater flow and transport pathways may differ significantly from those in underlying flow systems. Construction of multi-aquifer wells and groundwater withdrawal in perched systems can further alter such pathways.     

坐标转换及换带计算的研究与实验分析

针对工程测量中经常面临如何选择适合的控制网的中央子午线,如何实现新、旧控制网控制点坐标的统一,如何有效地克服长度变形等问题,阐述了不同坐标系之间的坐标成果转换和换代计算的方法,探讨了坐标转换基本模型的选用、转换参数的解算、转换计算的方法、转换计算中值得注意的问题,并根据坐标转换和换代计算公式,基于VB语言开发了坐标正反算程序、换代计算程序和简单梯形图幅编号查询程序,简要说明了这些程序的使用方法。并通过实例验证和分析了程序的精度和效率,结果证明程序设计正确,计算精度符合要求,达到了系统统一、简化施工、提高工作效率的目的。     

Factors structuring temporal and spatial dynamics of macrobenthic communities in a eutrophic coastal lagoon (Óbidos lagoon, Portugal)

The present work aimed to identify the main environmental drivers shaping temporal and spatial dynamics of macrobenthic communities within a eutrophic coastal lagoon. Sediments in the óbidos lagoon showed a gradient of increasing metal contamination from the inlet area to inner branches. The mid-lower lagoon area exhibited an intermediate contaminated condition between the inlet and upstream areas, suggesting that the effects of the organic loadings into the lagoon may be reflected until this area. This transitional feature was corroborated by biological data, with macrobenthic assemblages displaying characteristics of down- and upstream areas. Macrobenthic abundance peaked in winter, which was associated with a higher nutrient availability (mainly ammonium) and the proliferation of green macroalgae in mid-lower and inner lagoon areas. However, massive macroalgae growth resulted in a sharp decrease of macrobenthic diversity and abundance in spring, particularly where the higher amounts of decaying algae were detected. Higher dissimilarities between assemblages were detected during winter (and spring, for trophic composition), while in summer, differences were highly attenuated. The least contaminated area (close to the sea inlet) experienced smaller temporal variations for environmental variables, as well as the lowest temporal biological variability. This area was dominated by carnivores, which were related with increased salinity. Deposit-feeders were numerically dominant in the lagoon, being generally spread within organically enriched sandy and muddy areas. The high concentration of chlorophyll a and suspended particulate matter in water was reflected in the abundance of deposit-feeders/suspension-feeders, taking benefit of the high primary productivity. On the other hand, deposit-feeders/herbivores responded to the decay of macroalgae mats in the sediment. Biological associations varied with the biological data used (taxonomic versus trophic group composition; abundance versus biomass), highlighting the relevance of the combination of different data analysis' approaches. In general, BIOENV analysis indicated total phosphorus, biomass of Ulva, metals and organic carbon and nitrogen as being significantly influencing benthic patterns. On the other hand, discrepancies in ecological behaviours of some taxa were also detected in the present study stressing the need for additional studies on the relationships between macrobenthic communities and environmental variables. Implications of the present results for monitoring studies are discussed.     

图形(图像)面积的实时监测研究与分析

本文讨论采用自动化测量仪器全站仪自动、实时监测图形 (图像 )上的图斑面积 ,通过对点位、线长和面积的比较和精度分析 ,可以评定遥感图像 (地图 )上的图斑面积精度     

建立我国资源环境空间宏观监测与地面微观测量技术体系

我国资源、环境的监测多系以 RS、GPS RTK技术、GIS及其集成技术为基础的空间对地监测 ,这种监测体系比较宏观和粗放 ,对于全球性、全国性和大区域性是必要的、理想的 ,而对于局部地区的特殊的灾变环境和工程仍采用宏观监测 ,其精度就难以达到要求 ,而利用摄影测量、全站仪、GPS RTK、数字化测图与 GIS、三维工业测量等技术则是切实可行的监测手段 ,适合于对微观目标的精准测量。就建立我国资源与环境空间宏观监测和地面精准测量与监测体系问题进行了讨论 ,侧重讨论了宏观监测森林蓄积量和微观监测景观破碎带的理论、技术和方法     

金刚石的年龄,成因和置位：对过去十年科学进展的评述

进去十年中的科学进展大大增进了我们对金刚石的年龄和成因等方面的了解。现代分析技术使各＜２００μｍ的微细粒子的准确化学析成为可能。因此有可能进行金刚石中的矿物包裹体的地球化学研究，这就是过去十年科学进展的主要原因。概括来说，包体研究结果表明，大多数金刚石均产于两种类型岩石中：橄榄岩和榴辉岩。橄榄岩型金刚石的年龄为３３００Ｍａ，而榴辉岩型金钢石的年龄要轻一些，约为１０００－１５００Ｍａ。通常与金刚石伴