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951.
基于东莞市大气复合污染超级监测站的监测数据,选取2017年12月一次典型空气污染过程,对污染期间气象要素、大气颗粒物组分特征和污染物来源进行综合研究。结果表明,在污染期间,首要污染物为PM_(2.5),日均值为86μg/m3,其主要化学组分依次是OC、NO_3~-和SO_4~(2-),分别占PM_(2.5)的19.7%,16.1%和14.9%;在不利的气象条件下,本地污染排放和外源输入的一次污染物快速生成二次有机物、硝酸盐和硫酸盐,是造成该次空气污染的主要原因; PM_(2.5)污染主要来源为机动车尾气(27.7%)及二次无机源(19.0%)。 相似文献
952.
Comparative Studies on the Usefulness of Seven Ecological Indices for the Marine Coastal Monitoring Close to the Shore on the Swedish East Coast 总被引:1,自引:0,他引:1
The simultaneous behaviour of seven ecological indices(Hurlberts, Margalefs, Menhinicks, Shannons,species number, Jaccards and saprobic index) wasstudied based on phytoplankton data close to the shoreon the East coast of Sweden during the summer 1998.The sampling stations had a similar eutrophicationlevel and were located in bays. Standard phytoplanktondatabases were used in calculating the indices, whichwere later compared using cluster analysis.Hurlberts, Margalefs, Menhinicks, Shannons andspecies number indices, as measure of communitydiversity, produced similar trends which oftendiffered from those based on Jaccards index ofsimilarity. However, the simultaneous use of theseindices was found meaningful as a possible part of themonitoring close to the shore. The application of asaprobic index lead to erroneous conclusions in thestudied case. 相似文献
953.
Raja S Ravikrishna R Kommalapati RR Valsaraj KT 《Environmental monitoring and assessment》2005,110(1-3):99-120
Seventeen fog events were sampled in Baton Rouge, Louisiana during 2002–2004 as part of characterizing wet deposition by fogwater
in the heavily industrialized corridor along the Louisiana Gulf Coast in the United States. These samples were analyzed for
chemical characteristics such as pH, conductivity, total organic and inorganic carbon, total metals and the principal ion
concentrations. The dominant ionic species in all samples were NH4+, NO3−, Cl− and SO42−. The pH of the fogwater sampled had a mean value of 6.7 with two cases of acidic pH of 4.7. Rainwater and fogwater pH were
similar in this region. The acidity of fogwater was a result of NO3− but partly offset by high NH4+. The measured gaseous SO2 accounted for a small percentage of the observed sulfate concentration, indicating additional gas-to-particle conversion
of SO2 to sulfate in fogwater. The gaseous NOx accounted for most of the dissolved nitrate and nitrite concentration in fogwater. The high chloride concentration was attributable
to the degradation of chlorinated organics in the atmosphere. The metal composition was traced directly to soil-derived aerosol
precursors in the air. The major metals observed in fogwater were Na, K, Ca, Fe, Al, Mg and Zn. Of these Na, K, Ca and Mg
were predominant with mean concentrations > 100 μM. Al, Fe and Zn were present in the samples, at mean concentrations < 100
μM. Small concentrations of Mn (7.8 μM), Cu (2 μM), Pb (0.07 μM) and As (0.32 μM) were also observed in the fogwaters, and
these were shown to result from particulates (PM2.5) in the atmosphere. The contribution to both ions and metals from the marine sources in the Louisiana Gulf Coast was minimal.
The concentrations of all principal ionic species and metals in fogwater were 1–2 orders of magnitude larger than in rainwater.
Several linear alkane organic compounds were observed in the fogwater, representing the contributions from petroleum products
at concentrations far exceeding their aqueous solubility. A pesticide (atrazine) was also observed in fogwater, representing
the contribution from the agricultural activities nearby. 相似文献
954.
Combating desertification requires the involvement of many people ranging from communities who experience the effects on a
daily basis and scientists attempting to understand the biophysical and socio-economic causes and consequences of desertification,
to developers and policy makers on all levels. In many instances, however, the understanding, approaches and actions of these
different groups contradict rather than support one another. Over the period 2000 to 2002, a conference process undertaken
in southern Africa brought together communities, scientists, and development workers to test the concept that they could connect
and work together to combat desertification, given an appropriate framework. The conference was a success, and communities,
scientists and developers did exchange experience, knowledge and information. Many lessons were learned, although some pitfalls
were experienced. Time, funding, enhanced communication, and good will are the primary ingredients for ensuring that different
sectors complement one another in their efforts to combat desertification. 相似文献
955.
956.
957.
硅在海洋浮游植物群落演替过程中的作用 总被引:8,自引:0,他引:8
海洋浮游植物的群落演替是一处自然规律。每一局部水域,由于受各种特殊环境条件的调控和制约。具有其独特的浮游植物生礅类型。本文着重讨论了硅盐在浮游植物群落演替机制中手作用。并以大量的研究事例论证了这一理论的确立。 相似文献
958.
Long- and short-chain AHLs affect AOA and AOB microbial community composition and ammonia oxidation rate in activated sludge 总被引:1,自引:0,他引:1
Jie Gao Yu Duan Ying Liu Xuliang Zhuang Yichen Liu Zhihui Bai Wenlin M Guoqiang Zhuang 《环境科学学报(英文版)》2019,31(4):53-62
Quorum sensing (QS) regulation of the composition of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) communities and functions in wastewater treatment was investigated. Specifically, we explored the role of N-acyl-l-homoserine lactones (AHLs) in microbial community dynamics in activated sludge. On average, the specific ammonia-oxidising-rate increased from 1.6 to 2.8?mg?NH4+-N/g?MLSS/hr after treatment with long-chain AHLs for 16?days, and the addition of AHLs to sludge resulted in an increased number of AOA/AOB amoA genes. Significant differences were observed in the AOA communities of control and AHL-treated cultures, but not the AOB community. Furthermore, the dominant functional AOA strains of the Crenarchaeota altered their ecological niche in response to AHL addition. These results provide evidence that AHLs play an important role in mediating AOA/AOB microbial community parameters and demonstrate the potential for application of QS to the regulation of nitrogen compound metabolism in wastewater treatment. 相似文献
959.
Toward Sustainable Management of National Parks in Japan: Securing Local Community and Stakeholder Participation 总被引:4,自引:0,他引:4
Hiwasaki L 《Environmental management》2005,35(6):753-764
Japan’s national park system constitutes a potentially viable mechanism for securing local community participation and building stakeholder consensus for sustainable park management, although the potential of this system is yet to be fully maximized. This article gives an overview of the system of protecting natural resources in Japan, focusing on the national park system. Parks are managed by zoning and regulation, which is unique in that land is not “set aside” for nature conservation, but designated as national park wherever the need to preserve “scenic beauty” has been recognized, regardless of land ownership or land use. Although resource conservation under this system has been problematic, it has advantages, especially in terms of community participation. This article demonstrates that in order to reach the system’s potential, the park authority must act as coordinator of stakeholders and facilitator of bottom-up approaches to decision-making. In order to do this, steps that must be taken include the following: identifying the various stakeholders in park management and defining the “local community”; clarifying the roles and responsibilities of each stakeholder; and supporting consensus-building among stakeholders regarding the objectives and long-term vision of each park. By taking these steps, it would be possible to build a park management system that overrides government boundaries and involves local communities. This will enable the park authority to address the challenges facing Japan’s complex system of conserving natural resources, and move towards sustainable management of natural resources in Japan. 相似文献
960.
Ines Pöhler Dirk F. Wenderoth Katrin Wendt-Potthoff Manfred G. Höfle 《Water, Air, & Soil Pollution: Focus》2002,2(3):111-121
In an acid mining lake (pH 2.6) enclosure experiments wereperformed with the addition of different concentrations oforganic carbon, nitrogen and phosphorus. SSCP-communityfingerprints, based on 16S rRNA gene amplicons, were performed tomonitor changes in the structure of the total bacterialcommunity and the sulfate reducing bacteria (SRB) in themesocosms. Total bacterial cell counts, as assessed byepifluorescence microscopy, were increased in the mesocosmsamended with organic carbon. The addition of carbon alsoincreased the number of abundant bacterial taxa substantiallyalong depth. Sulfate reducing bacteria (SRB) could be detected inall enclosures and all parts of the water column. These SRBbelonged to genus Desulfobacter as indicated bycoroborating molecular data. 相似文献