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91.
Guanabara Bay (GB) is considered to be one of the most polluted environments of the southern Brazilian coastline. This typical estuarine system is impacted by the heavy discharge of both industrial and domestic waste from the Rio de Janeiro metropolitan area. The mollusc community structure and distribution was investigated between 2000 and 2001, using a three month sampling design of 38 stations, according to austral seasons. Species abundance was aggregated into progressively higher taxa matrices (genus, family, order) and were analysed using multivariate techniques. Mollusc distribution in GB varied significantly in space and time and was probably ruled by the organic enrichment effects of hypoxia and altered redox conditions coupled with prevailing patterns of circulation. Within the sectors of GB an increasing gradient in mollusc diversity and occurrence was observed, ranging from the azoic and impoverished stations in the inner sector to a well-structured community in terms of species composition and abundance inhabiting the outer sector. The non-metric multidimensional scaling (nMDS) and cluster analysis showed similar results when species were aggregated into genera and families, while greater difference occurred at coarser taxonomic identification (order). The literature about taxonomic sufficiency has demonstrated that faunal patterns at different taxonomic levels tend to become similar with increased pollution. In Guanabara Bay, an analysis carried out solely at family level is perfectly adequate to describe the ecophysiological stress. Further aggregation to order level changed the perceived patterns of differences. However, a different taxonomic resolution can be chosen depending on the type of ecological patterns investigated. 相似文献
92.
Echavarri-Erasun B Juanes JA García-Castrillo G Revilla JA 《Marine pollution bulletin》2007,54(7):941-954
An investigation on the effects of deepwater outfall discharges on the status of rocky reef communities was carried out. The sanitation system was found to be an environmentally suitable option for the protection of those habitats situated in high energy coastal environments. Sediments occurring between the predominating rocky substrates showed low values of the fine fraction (<63microm) and organic matter content. In addition, high average concentrations of Cd, Hg and Zn were found in these sediments, though these values were similar to those registered in non-affected sites, far away from the outfall. On the other hand, those assemblages typical of hard substrates that settled near the outfall showed an increase in total richness and abundance of macroinvertebrates. Moreover, the average number of species of each taxonomic group, a good indicator of the maintenance of the previous trophic structure, only varied considerably over time at the rip-rap protection. In a global context, those changes were not directly related to the discharge disturbances, but to the natural variability or the successional processes occurring within those communities. Only communities dwelling in the rip-rap protection area were affected by the proximity of the discharges. 相似文献
93.
Benthic meiofauna community composition at polluted and non-polluted sites in New Zealand intertidal environments 总被引:1,自引:0,他引:1
Meiofauna composition was investigated for six field sites, including polluted and non-polluted sites, within two regions (Auckland and Bay of Plenty) during winter (July-August 2004) in the North Island of New Zealand. Physico-chemical parameters were measured during the sampling period and meiofauna distribution and abundance were compared with these measured parameters. Analysis of meiofauna abundance indicated that foraminiferans, nematodes and ostracods were the taxa that contributed to the variability between field sites within the Auckland region. However, no clear taxa dominance was seen in the Bay of Plenty region. Comparison of meiofauna abundance and physico-chemical parameters was done using multivariate analysis (PRIMER). However, no clear relationships between the parameters were observed in any field site in either region. The Shannon-Weiner index of diversity did not show any clear differentiation between polluted and non-polluted field sites. Therefore, from the present study, the taxa or physico-chemical parameters used could not effectively characterise pollution at the investigated field sites. 相似文献
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由于灰色系统考虑了系统内部因素相互关系不完全清楚性,因而应用灰色局势决策法选择水利工程实施方案.更具有客观性、科学性。以某水利工程为实例,介绍了用灰色局势决策法对实施方案进行优选的原理和方法,通过实例证明:灰色局势决策法具有较好的实用性,且操作简便。 相似文献
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随着互联网技术的不断发展和电子商务的不断运用,全球经济日趋一体化,国际、国内的企业竞争越来越激烈,我国企业也面临着巨大的机遇与挑战,迫切需要借助信息化手段利用全球市场资源实现快速发展,由于受到跨国公司核心技术、市场策略等多种因素的制约,以及我国"振兴规划"不确定因素的影响,当前我国企业信息化建设和发展仍面临许多困难和问题,期望得到政府协调解决,使企业信息化建设进展顺利。 相似文献
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矿井地质是一门探索性、适用性都非常强的技术科学,是在煤田地质勘查的基础上、在矿井建设和生产期间、直接为煤矿建设和生产服务的一项重要技术基础工作。我国的矿井地质工作是随着煤炭工业的迅速发展而建立和发展起来的,并积累了丰富的实践经验,逐步形成了一套比较完整的工作内容和工作方法,它对煤矿建设和生产起着重要的作用,其发展历程可划分为四个阶段:初期创立阶段、曲折发展阶段、开拓前进阶段和发展提高阶段。随着我国经济的快速发展,煤炭需求量也随之持续增长,煤炭开采逐步向深部等难采块段及边缘地区推进,其地质条件日趋复杂,开采难度加大,因此矿井地质工作必须做好基础地质的研究工作,重视高新技术应用,完善地质保障体系,逐步提高勘探精度。 相似文献
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用于海上油气田的压裂作业船具备高效性和安全性,具有优越的操控性能和良好的稳定性,配备了先进的船舶航行系统、动力定位系统和强大的动力系统.全船配备的压裂作业设备包括支撑剂存储装置,酸液和胶液存储装置,搅拌混合系统,各类液体和化学药剂添加系统,压裂作业泵系统,中央控制室以及数据采集系统,完备的质量控制体系,安全的作业管线和快速脱离装置.压裂作业船能连续施工作业,效率高,安全可靠. 相似文献