Assessment of groundwater contamination using geographic information systems

In this study two sites were selected in order to investigate groundwater contamination and spatial relationships among groundwater quality, topography, geology, landuse and pollution sources. One site is the Asan area, an agricultural district where pollution sources are scattered and which is mainly underlain by granite of Cretaceous age. The other site is the Gurogu area of Seoul city, an industrial district where an industrial complex and residential areas are located and which is mainly underlain by gneiss of Precambrian age. Groundwater samples collected from these districts were analysed for chemical constituents. An attribute value files of chemical constituents of groundwater and the spatial data layers were constructed and pollution properties were investigated to establish out spatial relationships between the groundwater constituents and pollution sources using geographic information systems (GIS).Relatively high contents of Si and HCO₃ ^– in the groundwater from the Asan area reflect the effect of water–rock interaction whereas high contents of Cl^–, NO₃ ^– and Ca²⁺ in the groundwater from the Gurogu area are due to the pollution of various sources. The significant seasonal variation of SiO₂, HCO₂ ^– and Ca²⁺ contents, and that of Ca²⁺ content were observed in the Asan and the Gurogu areas, respectively. Seasonal variation of pollutants such as Cl^–, NO₃ ^– and SO₄ ^2– was not observed in either area. Pollution over the critical level of the Korean drinking water standard has been investigated from 15 sampling sites out of 40 in the Asan area, and 33 sampling sites out of 51 in the Gurogu area. Pollution by NO₃ ^–, Cl^–, Fe²⁺, Mn²⁺, SO₄ ^2– and Zn²⁺ in the groundwater from the industrial district (Gurogu area) and that of NO₃ , SO₄ ^2– and Zn²⁺ in the groundwater from the agricultural district (Asan area) were observed. The principal pollutant in both areas is NO₃ ^–. Deep groundwater from the Asan area is not yet contaminated with NO₃ ^– except for one site, but most of the shallow groundwater site occurring near the potential point sources is seriously contaminated. From the result of buffering analysis, it seems clear that factories and stock farms are the principal pollution sources in the Asan area. The groundwater from the Gurogu area has already been seriously polluted considering the fact of NO₃ ^– contamination of deep groundwater. Chlorine pollution of shallow groundwater in the Gurogu area was also observed. Spatial relationship between pollution level and its source was clarified in this study by using GIS, which will be applicable to the effective management of groundwater quality.     

沈阳市大气PM2.5中水溶性离子的季节变化特征

为研究沈阳市大气中PM2.5及其水溶性离子的污染特征、季节差异和来源情况,使用URG-9000D在线监测系统对沈阳市2019年大气颗粒物进行连续的采样分析,并利用正交矩阵因子分析法(PMF)进行污染物的来源解析.结果 表明,2019年沈阳市秋冬季节PM2.5质量浓度变化受相对湿度影响较大,冬季PM2.5平均质量浓度达到85.76 μg·m-3,细粒子污染较为严重.沈阳市大气PM2.5中SNA(SO42-、NO3和NH4+)所占比重表现为春季最高秋季最低;夏季SO42-和NH4+浓度较高,而NO3-浓度较低.SO42-在夏季呈单峰型日变化,与NO3-变化趋势相反.春夏秋三季NH4+与SO42-、NO3-主要结合为(NH4)2SO4和NH4NO3,冬季NH4+主要以(NH4)2SO4和NH4HSO4的形式存在.沈阳市存在较强的SO2和NOx二次转化现象,且各季节中SO2的转化率均高于NO2.PMF源解析结果表明,二次源对沈阳市大气污染贡献最大,夏秋季生物质燃烧和冬季燃煤源贡献同样不可忽视.     

Response of fluctuating asymmetry to arsenic toxicity: support for the developmental selection hypothesis

The effect of exposure to sodium arsenite during development was tested on adult fluctuating asymmetry (FA) in sternopleural bristle number, bristle number, body size and survivorship in Drosophila melanogaster. Three genetic strains of flies were used, CT-106, PVM and Oregon-R, and arsenite concentrations ranged from relatively mild, sub-lethal doses, to concentrations with pronounced negative effects on survivorship. At arsenite concentrations of 1.0 and 0.125 mM, mortality was on average 38% greater than in controls, and surviving flies emerged significantly smaller and had fewer bristles than controls. Neither the effect of arsenite or the genotype x environment interaction on asymmetry were significant. However, given the high mortality, any increase in FA could have been masked by the outcome of developmental selection against developmentally unstable phenotypes. We tested for this effect by contrasting FA values between (1) flies reared at the highest concentrations used previously, (2) flies reared at sub-lethal dosage, and (3) controls. Positional fluctuating asymmetry (PFA), which is expected to be a sensitive indicator of underlying developmental stability, was significantly reduced among flies reared at the highest concentration, and at which flies suffered significant mortality. Moreover, the slope of the regression relating mean PFA to emergence per bottle was significantly positive. These data support the hypothesis that developmental selection occurred in this experiment, and that the expected positive relationship between asymmetry and stress may be altered when the stressor eliminates individuals from the population. In contrast, FA of flies reared at sub-lethal dosage did not differ from that in controls, a result that fails to support the hypothesis that arsenite disrupts developmental stability. Our results call for caution in FA-based biomonitoring, especially of potentially lethal forms of stress, because in the presence of developmental selection, and under the common assumption that FA should increase under stress, erroneous conclusions may be drawn about the health and well being of a population. It is suggested that FA-based biomonitoring efforts integrate the use of FA with other bioindicators, and experimentally validate any expected FA-stress relationship before attempting to infer the presence of environmental stress.     

The politics of preserving natural areas in Third World States

Summary Any attempts to preserve Third World ecosystems must recognize that the ultimate decisions lie with the governments of these sovereign states, which have to deal with widespread demands for higher living standards as well as growing populations. To deal with the powerful pressures of economic growth, the most promising strategy for conservationists is to press the Western industrialized states, where the conservation movement is relatively strong, to join with the Third World in an international agreement whereby the latter would preserve portions of threatened ecosystems in exchange for compensation provided from the industralized countries, most plausibly through an agreement to reduce Third World countries' debt. To reinforce this protection, the industrialized states could agree to purchase tropical ecosystem products only from those states which agree to preserve certain portions of their ecosystems. While there would be great problems both in working out the levels of compensation and in persuading the industrialized states to participate in such a scheme, intensive lobbying by conservation groups might be enough to bring it to fruition.Dr. John Cartwright, who teaches courses in environmental politics and African politics at the University of Western Ontario, took degrees from Queen's University in Kingston, Canada, and the University of Toronto. From 1963 to 1966 he taught at the University of Sierra Leone in Freetown. He has produced three books on African politics, his most recent beingPolitical Leadership in Africa (1983). He has also been interested for many years in natural history and conservation issues, which have taken him on several visits to Latin America as well as to Africa.     

Improving species status assessments under the U.S. Endangered Species Act and implications for multispecies conservation challenges worldwide

Despite its successes, the U.S. Endangered Species Act (ESA) has proven challenging to implement due to funding limitations, workload backlog, and other problems. As threats to species survival intensify and as more species come under threat, the need for the ESA and similar conservation laws and policies in other countries to function efficiently has grown. Attempts by the U.S. Fish and Wildlife Service (USFWS) to streamline ESA decisions include multispecies recovery plans and habitat conservation plans. We address species status assessment (SSA), a USFWS process to inform ESA decisions from listing to recovery, within the context of multispecies and ecosystem planning. Although existing SSAs have a single-species focus, ecosystem-based research can efficiently inform multiple SSAs within a region and provide a foundation for transition to multispecies SSAs in the future. We considered at-risk grassland species and ecosystems within the southeastern United States, where a disproportionate number of rare and endemic species are associated with grasslands. To initiate our ecosystem-based approach, we used a combined literature-based and structured World Café workshop format to identify science needs for SSAs. Discussions concentrated on 5 categories of threats to grassland species and ecosystems, consistent with recommendations to make shared threats a focus of planning under the ESA: (1) habitat loss, fragmentation, and disruption of functional connectivity; (2) climate change; (3) altered disturbance regimes; (4) invasive species; and (5) localized impacts. For each threat, workshop participants identified science and information needs, including database availability, research priorities, and modeling and mapping needs. Grouping species by habitat and shared threats can make the SSA process and other planning processes for conservation of at-risk species worldwide more efficient and useful. We found a combination of literature review and structured discussion effective for identifying the scientific information and analysis needed to support the development of multiple SSAs. Article impact statement: Species status assessments can be improved by an ecosystem-based approach that groups imperiled species by shared habitats and threats.     

Measuring settlement intensity of echinoderms on coral reefs

A pilot study was conducted at Davies Reef on the central Great Barrier Reef between 20 November 1991 and 20 January 1992 to assess the suitability of settlement collectors for measuring larval settlement rates of echinoderms on coral reefs. The collectors were deployed for two months during summer when many echinoderm species are known to spawn. A total of 657 newly settled echinoderms were recovered from just 47 collectors, each having a volume of just 0.005 m³ but with a utilisable surface area of about 1.44 m², indicating that competent-to-settle larvae were very abundant during the sampling period. Echinoids (7.8 sampler^-1) and ophiuroids (5.6 sampler^-1) were the most abundant groups on the collectors. Asteroids (0.2 sampler^-1) and crinoids (0.3 sampler^-1 were less common. The asteroids were all identified to species and included the crown-of-thorns starfish Acanthaster planci, Choriaster granulatus and Culcita novaeguineae. The newly settled echinoids could not be distinguished from each other but included Echinometra mathaei and Mespilia globulus. The abundance of each of the five different classes of echinoderms on the samplers was correlated with their abundance on the natural substratum. Significant spatial variability was found in settlement rates of echinoids over 1000s of metres and ophiuroids over 100s of metres, but not over smaller spatial scales. It is concluded that the collectors can provide a useful tool for monitoring spatial and temporal variability in settlement rates of echinoderms on coral reefs and for testing hypotheses about patterns of larval dispersal.