How to improve reliability in groundwater analysis: over a decade of experience with external quality control in field campaigns on volatile halogenated compounds

The reliability in measurement results obtained during environmental monitoring is crucial for the assessment and further planning of remediation efforts on the respective contaminated sites by the responsible authorities. A case study concerned with groundwater contaminated with perchloroethylene, trichloroethylene and 1,1,2-trichlorotrifluoroethane including their degradation products which involves private contract laboratories and an independent provider of quality assurance (QA) is presented. The experience gained with biannual monitoring campaigns over 14 years indicates that the selection of contractors on basis of accreditation status and successful performance in interlaboratory comparisons are not sufficient. Rather the auditing of the contractors by the QA provider prior to each campaign and the crosschecking of selected monitoring samples by the QA provider led to a lasting improvement of reliability in the contractors' measurement results. A mean deviation of 20% from the reference value determined by the QA provider for the crosschecked samples was reached.     

锡林河流域地表水水化学主离子特征及控制因素

通过对2006~2008年锡林河主要径流期内13个河水断面239个水样以及同期地下水和大气降水主离子水化学进行分析,结合锡林河流域的气象和水文资料,利用Piper三线图和Gibbs图分析了锡林河河水的水化学特征及主离子组成变化特征.结果表明,锡林河河水TDS变化范围在136.7~376.5 mg·L-1之间,平均245.1 mg·L-1,为低矿化度河水;河水中主要阳离子以Ca2+为主,阴离子以HCO-3为主,河水的水化学类型从HCO-3-Ca2+过渡到HCO-3-Ca2+·Mg2+;河水主离子平均浓度年内、年际变化均不大,年内变化表现在5月主离子浓度高于其他月,年际变化表现为主离子在2007年的平均浓度均较小;空间上,Ca2+、Na+、Mg2+、K+、Cl-和HCO-3的浓度呈现沿程逐渐增加的趋势,SO2-4的浓度变化呈先增加后减小的趋势;河水中主离子浓度值介于大气降水和地下水之间,并且十分接近地下水浓度,说明地表水同时受大气降水和地下水补给并主要依靠地下水补给;Gibbs图显示河水离子组成主要与流域内的岩石风化有关,流域有一定量的蒸发岩存在,但蒸发岩对水化学的贡献弱于碳酸盐岩.     

No discrimination against previous mates in a sexually cannibalistic spider

In several animal species, females discriminate against previous mates in subsequent mating decisions, increasing the potential for multiple paternity. In spiders, female choice may take the form of selective sexual cannibalism, which has been shown to bias paternity in favor of particular males. If cannibalistic attacks function to restrict a male's paternity, females may have little interest to remate with males having survived such an attack. We therefore studied the possibility of female discrimination against previous mates in sexually cannibalistic Argiope bruennichi, where females almost always attack their mate at the onset of copulation. We compared mating latency and copulation duration of males having experienced a previous copulation either with the same or with a different female, but found no evidence for discrimination against previous mates. However, males copulated significantly shorter when inserting into a used, compared to a previously unused, genital pore of the female.     

沿海和海洋生态系统与人类人口系统间的相互作用:关于消费如何调解这种相互作用的看法

人口、环境及可持续发展的困境 20世纪的80和90年代,环境工作者和普通公众普遍认为,不加控制的人口增长是造成各类环境退化的根本原因.这种新马尔萨斯人口论的观点最初出现在20世纪60年代Ehrlich所著的<人口炸弹>的文章中,该文以危言耸听的语气解释了那十年空前高的人口增长率[1～3].     

Evolutionary relationships of deep-sea hydrothermal vent and cold-water seep clams (Bivalvia: Vesicomyidae): results from the mitochondrial cytochrome oxidase subunit I

Phylogenetic relationships among vesicomyid clams (Bivalvia: Vesicomyidae) and their placement within the order Heterodonta were examined using mitochondrial encoded cytochrome oxidase subunit I (COI) DNA sequences. The presently analyzed vesicomyids represent a recent monophyletic radiation that probably occurred within the Cenozoic. Nucleotide phylogenetic analyses resolved discrete clades that were consistent with currently recognized species: Calyptogena magnifica, C. ponderosa, Ectenagena extenta, C. phaseoliformis, Vesicomya cordata, Calyptogena n. sp. (Gulf of Mexico), C. kaikoi, C. nautilei, C. solidissima and C. soyoae (Type-A). However, specimens variously identified as: V. gigas, C. kilmeri, C. pacifica, and V. lepta comprised two “species complexes”, each composed of multiple evolutionary lineages. Most taxa are limited to hydrothermal-vent or cold-seep habitats, but the “vent” versus “seep” clams do not constitute separate monophyletic groups. Current applications of the generic names Calyptogena, Ectenagena, and Vesicomya are not consistent with phylogenetic inferences. Received: 24 July 1997 / Accepted: 22 August 1997     

Evolution of habitat use by deep-sea mussels

Previous phylogenetic studies proposed that symbiont-bearing mussels of the subfamily Bathymodiolinae (Bivalvia: Mytilidae) invaded progressively deeper marine environments and evolved from lineages that decomposed wood and bone to specialized lineages that invaded cold-water hydrocarbon seeps and finally deep-sea hydrothermal vents. To assess the validity of the hypotheses, we examined two nuclear (18S and 28S rRNA) and two mitochondrial genes (COI and ND4) from a broad array of bathymodiolin species that included several recently discovered species from shallow hydrothermal seamounts. Bayesian phylogenetic analysis and maximum-likelihood estimates of ancestral character states revealed that vent species evolved multiple times, and that reversals in vent and seep habitat use occurred within the sampled taxa. Previous hypotheses regarding evolution from wood/bone-to-seeps/vents are supported in that mid-ocean hydrothermal vent species may represent a monophyletic group with one noticeable reversal. Earlier hypotheses about progressive evolution from shallow-to-deep habitats appear to hold with a few instances of habitat reversals.     

Characterization of Drought in the South Atlantic,United States

Drought has been less extensively characterized in the humid South Atlantic compared to the arid western United States. Our objective was to characterize drought in the South Atlantic and to understand whether drought has become more severe in this region over time. Here we used monthly streamflow to characterize hydrological drought. Hydrological drought occurred when streamflow fell below the 20th percentile over three consecutive months and terminated once streamflow remained above the 20th percentile for three consecutive months. We characterized the frequency, duration, magnitude, and severity of events using the above definition. Significant changes in drought characteristics were tested with Mann‐Kendall over three periods: 1930‐2010, 1930‐1969, and 1970‐2010. We show that 71% of drought events were shorter than six months, while 7% were multiyear events. There was little evidence of trends in drought characteristics to support the claim of drought becoming more severe in the South Atlantic over the 20th Century. The one exception was a significant increase in the joint probability of nearby basins being simultaneously in drought conditions in the southern portion of the study area from 1970 to 2010. While drought characteristics have changed little through time, decreasing average streamflow in non drought periods coupled with increasing water demand provide the context within which recent multiyear drought events have produced significant stress on existing water infrastructure.     

建造能源-效率的城市网络：欧洲和巴西的一些实践经验

今天的能源政策不得不把面向能源供应和能源需求两个主动性结合起来 .鉴于油价危机以来逐渐增加的环境限制的压力和节能行为，一个基于能源消耗管理和增加利用地方（可更新的）能源的新能源政策，已变得十分必要 .在这一研究里，地方和区域一级是合作伙伴 .能源效率项目的发展和市政府之间有关最佳实践信息的交换和传播，正在由节能机构的网络在世界范围组织起来 .下面就是这样的网络发展的几个实例 .……