Anthropogenic tracers, endocrine disrupting chemicals, and endocrine disruption in Minnesota lakes

Concentrations of endocrine disrupting chemicals and endocrine disruption in fish were determined in 11 lakes across Minnesota that represent a range of trophic conditions and land uses (urban, agricultural, residential, and forested) and in which wastewater treatment plant discharges were absent. Water, sediment, and passive polar organic integrative samplers (POCIS) were analyzed for steroidal hormones, alkylphenols, bisphenol A, and other organic and inorganic molecular tracers to evaluate potential non-point source inputs into the lakes. Resident fish from the lakes were collected, and caged male fathead minnows were deployed to evaluate endocrine disruption, as indicated by the biological endpoints of plasma vitellogenin and gonadal histology. Endocrine disrupting chemicals, including bisphenol A, 17β-estradiol, estrone, and 4-nonylphenol were detected in 90% of the lakes at part per trillion concentrations. Endocrine disruption was observed in caged fathead minnows and resident fish in 90% of the lakes. The widespread but variable occurrence of anthropogenic chemicals in the lakes and endocrine disruption in fish indicates that potential sources are diverse, not limited to wastewater treatment plant discharges, and not entirely predictable based on trophic status and land use.     

现实中的梦想 上海

在所有的通商口岸中,上海是独一无二的,在没有任何构筑物和历史的土地上发展成了一座全新的城市。它也因此成为了一个容纳外国人的梦想和欲望的开放之地。虽然这些梦想的初衷早已被遗忘,却还是存留于已经建成的现实之中。这篇文章思考了它们在城市个性成型过程中的作用。     

Do existing ecological classifications characterize the spatial variability of stream temperatures in the Great Lakes Basin,Ontario?

Ecological classifications of stream ecosystems have been used to develop monitoring programs, identify reference and impacted systems, and focus conservation efforts. One of the most influential, but highly variable, components of stream ecosystems is water temperature but few geographically broad-scale and long-term programs exist to assess and monitor temperatures. This study evaluated if existing ecological classifications could be used to categorize the similarities and differences in stream temperatures across the Ontario portion of the Great Lakes Basin. Concordance between the spatial variability in temperatures and an existing ecological classification would support the use of that classification to define areas with similar temperatures, guide the development of a monitoring program, and inform management programs. The five classifications evaluated were the ecoregions and ecodistricts defined in the National Ecological Framework for Canada, the ecoregions and ecodistricts defined in the Ecological Land Classification of Ontario, and the aquatic ecosystem units defined in the Aquatic Ecosystem Classification (AEC) for the Ontario portion of the Great Lakes Basin. Hierarchical linear modelling and corrected Akaike Information Criterion indicated that the ecodistrict classifications characterized more of the spatial variability in temperatures than the ecoregion and AEC classification but temperatures were more variable among sites within classes than between classes. Therefore, none of the existing ecological classifications could be used to characterize thermal variability. Future research should examine if the inability of the existing classifications to capture the thermal variability translates into inaccurate classification of other ecosystem components such as water quality, and macroinvertebrate and fish assemblages.     

Density,production, and survival of walleye (Sander vitreus) eggs in the Muskegon River,Michigan

Walleye (Sander vitreus) is an important sport fish in the Great Lakes that is experiencing low reproductive success after severe population declines starting in the late 1940s. In the Muskegon River, Michigan, natural reproduction of walleyes remains low and is largely supplemented by stocking. To determine factors influencing walleye reproductive success in the Muskegon River, we estimated walleye egg survival using insitu egg incubators covered with nitex screening (2003–2004) and estimated density and survival of fertilized eggs caught on furnace filter traps across different substrate types (2005–2006). We compared physical habitat suitability for walleye eggs under high and low flow scenarios. Density of walleye eggs was highest in regions of gravel/cobble substrates. Egg survival was higher in egg incubators (24–49.5%) than on furnace filter traps (2.0%), suggesting predation is an important source of walleye egg mortality in the Muskegon River. Cold water temperatures that extended developmental stage durations may also be an important source of egg mortality. The dynamic habitat suitability model predicted low suitability for eggs due to poor temperature and velocity conditions. Despite low egg survival rates, 40 million to 1 billion eggs were estimated to hatch. The low natural reproduction of walleyes in the Muskegon River is likely due to a combination of low walleye egg survival and failure of walleye larvae to reach their nursery grounds in Muskegon Lake.     

Characteristics of double-crested cormorant colonies in the U.S. Great Lakes island landscape

The Great Lakes form the largest freshwater island system in the world and provide breeding habitat for a large proportion of the continental population of double-crested cormorants (Phalacrocorax auritus). Here, cormorants have a high profile due to conflicts with humans; by 2007, most active (64%) breeding sites in U.S. waters were managed. This study used data from the U.S. Great Lakes Colonial Waterbird Database and The Nature Conservancy's Great Lakes Island GIS database to identify important features of breeding sites in the U.S. Great Lakes and broaden understanding of cormorant presence at the island-landscape scale. Islands 0.5–10 ha were used more frequently than expected, and most sites had remoteness values of ≤ 3 km. Colony size was positively correlated with years occupied and large colonies (> 1000 pairs) developed primarily (95%) on island sites > 1.0 ha. Sites supporting large colonies were more remote than those supporting smaller colonies. Presence of other colonial waterbird species, especially Herring Gulls (Larus argentatus), also characterized cormorant sites. Islands used by cormorants comprised a small proportion (n = 90, 3%) of the U.S. Great Lakes island resource, and < 1% of the total island area. Certain characteristics of breeding sites (e.g., small islands, proximity to mainland) may increase negative attitudes about cormorants. To understand cormorant impacts to island resources (e.g., vegetation; other colonial waterbird species), we suggest cormorant presence in the Great Lakes be considered in the broader context of island science, conservation and known threats, and at a landscape scale.     

水城明尼阿波利斯的公园体系

以水著称的明尼阿波利斯公园体系,是美国19世纪中后期城市公园勃兴时期的产物,也是美国城市规划史上的成功范例之一,它在明尼阿波利斯城市扩张的过程中起到了导向作用。它以环绕城区的链状水体为核心景观,并以水畔的“大环”风景路将各种公园、花园、场地及休闲设施整合为一个公园体系,为城市旅游休闲业、地产业提供了契机,其宽阔的林荫路系统、精彩的“湖链”区也成为城市交通、防灾及生态系统的重要组成部分,起到了积极的作用。该体系在规划、景观设计及维护管理等方面都堪称典范,对我国公园的建设发展具借鉴价值。     

Population structure of Cladophora-borne Escherichia coli in nearshore water of Lake Michigan

We previously reported that the macrophytic green alga Cladophora harbors high densities (up to 10(6) colony-forming units/g dry weight) of the fecal indicator bacteria, Escherichia coli and enterococci, in shoreline waters of Lake Michigan. However, the population structure and genetic relatedness of Cladophora-borne indicator bacteria remain poorly understood. In this study, 835 E. coli isolates were collected from Cladophora tufts (mats) growing on rocks from a breakwater located within the Indiana Dunes National Lakeshore in northwest Indiana. The horizontal fluorophore enhanced rep-PCR (HFERP) DNA fingerprinting technique was used to determine the genetic relatedness of the isolates to each other and to those in a library of E. coli DNA fingerprints. While the E. coli isolates from Cladophora showed a high degree of genetic relatedness (92% similarity), in most cases, however, the isolates were genetically distinct. The Shannon diversity index for the population was very high (5.39). Both spatial and temporal influences contributed to the genetic diversity. There was a strong association of isolate genotypes by location (79% and 80% for lake- and ditch-side samplings, respectively), and isolates collected from 2002 were distinctly different from those obtained in 2003. Cladophora-borne E. coli isolates represented a unique group, which was distinct from other E. coli isolates in the DNA fingerprint library tested. Taken together, these results indicate that E. coli strains associated with Cladophora may be a recurring source of indicator bacteria to the nearshore beach.     

中国金刚石使用历史超过4500年

通过在国际学术界首次破解夜明珠这一世界性的自然、历史、文化千古之谜和首次创立金刚石考古地质学的理论和方法,以夜明珠就是中国古代巨粒金刚石为例,证明了中国巨粒金刚石开发利用的历史可以一直追溯到4000年前的尧、舜、禹时期甚至4500年前的炎帝时期。这一成果将之前国际学术界普遍认为人类使用金刚石不超过2500年的历史推前了至少2000年,比起哈佛学者使用物理学方法研究刚玉石斧得出中国人使用金刚石粉末加工刚玉石器历史超过4500年的类似结论领先了一年左右的时间。     

大兴安岭东南段哈拉苏西铅锌多金属矿床地质特征及成因探讨

大兴安岭东南段晚侏罗世—早白垩世火山—岩浆活动强烈,形成了以北北东向构造控制的构造岩浆岩带,发现多处与其相关的铅锌银矿床。在充分收集已有地质、物探和化探资料的基础上,分析了哈拉苏西铅锌多金属矿矿区和矿体地质特征,提出了矿床成因机制和找矿方向。研究为大兴安岭东南段与火山—岩浆作用相关中低温热液型金属矿的发现提供了基础地质资料和勘查找矿思路。     

International Rivers as Boundaries

Abstract

International rivers serve a number of purposes, the most obvious are the navigational and non-navigational uses. Less noticed is the fact that international rivers are also used to delimit boundaries between nations. The immediate question that would arise is: Where are such boundaries actually drawn across the river? Boundaries, however, are established by treaties and the answer to this question is often included in the interpretation of treaties delimiting such water boundaries, taking into account the special characteristics of the international river. Indeed, this has been the case regarding the boundaries across the Chobe river between Botswana and Namibia. Determining where such boundaries lie would result in deciding to whom a disputed Island, the Kasikili/Sedudu, belongs. In a praiseworthy step, the two countries agreed to take their dispute over the Island, after failure to resolve it through negotiations, to the International Court of Justice. This paper discusses the uses of international rivers as boundaries, and reviews the dispute between Botswana and Namibia, and the decision of the Court thereon.