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1.
Critics of the Endangered Species Act have asserted that is protects an inordinate number of subspecies and populations, in addition to full species, and that the scientific rationale for listing decisions is absent or weak. We reviewed all U.S. plants and animals proposed for listing or added to the endangered species list from 1985 through 1991 to determine the relative proportion of species, subspecies, and populations, and their rarity at time of listing. Approximately 80% of the taxa added to the list were full species, 18% were subspecies, and 2% were distinct populations segments of more widespread vertebrate species. The proportion of subspecies and populations was considerably higher among birds and mammals than among other groups. The median populations size at time of listing for vertebrate animals was 1075 individuals; for invertebrate animals it was 999. The median population size of a plant at time of listing was less than 120 individuals. Earlier listing of declining species could significantly improve the likelihood of successful recovery, and it would provide land managers and private citizens with more options for protecting vanishing plants and animals at less social or economic cost. 相似文献
2.
David S. Reay Keith A. Smith Anthony C. Edwards 《Water, Air, & Soil Pollution: Focus》2004,4(2-3):437-451
Dissolved nitrous oxide (N2O), nitrate (NO3 -), and ammonium (NH4 +) concentrations in an agricultural field drain were intensively measured over the period of field nitrogen (N) fertilisation and for several weeks thereafter. Supersaturations of dissolved N2O were observed in field drain waters throughout the study. On entry to an open drainage ditch, concentrations of dissolved N2O rapidly decreased and a total N2O-N emission via this pathway of 13.2 g over the period of study (45 days) was calculated. This compared with a predicted emission of the order of 300 g, based on measured losses of NO3 - and NH4 + in the field drainage water, and the default IPCC emission factor of 0.01 kg N2O-N per kg Nentering rivers and estuaries. In contrast to widespread evidence of a clear relationship between the amount of N applied to agricultural land and subsequent direct N2O emission from the soil surface, the relationship between the amount of N2O in soil drainage waters and the amount of N applied was poor. We conclude that the complexity, both spatially and temporally, of the processes ultimately responsible for the amount of N2O in agricultural drainage waters make a straightforward relationship between N2O concentration and N application rate unlikely in all but the simplest of systems. 相似文献
3.
4.
George R. Hendrey Keith F. Lewin Zbigniew Kolber Lance S. Evans 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1324-1327
A prototype Free-Air Controlled Enrichment (FACE) system was developed at Brookhaven National "Laboratory (BNL) for the experimental control of gas concentrations in an open field, without any form of enclosure. This FACE system consists of a toroidal plenum chamber, 15 m in diameter, with a series of 32 vertical vent pipes from which the release of a test gas can be controlled. Data on gas concentration at the center of the array and wind velocity are fed to a microprocessor where a proportional, integrative, differential (PID) algorithm is used to regulate a mass-flow controller. Data on wind direction are used to control the opening and closing of the vertical vent pipes to maintain an upwind release. In 72 hours of continuous operation during which wind velocity varied between 0.3 to 8 m sec-1, the FACE prototype maintained 1 -min averaged concentrations within twenty percent of the 40 ppb set point 94 percent of the time. 相似文献
5.
To study the Pu concentration and isotope ratio distributions present in China, the 239+240Pu total activities and 240Pu/239Pu atom ratios in core soil samples from Hubei Province in central China were investigated using Accelerator Mass Spectrometry (AMS). The activities ranged from 0.019 to 0.502 mBq g−1 and the 239+240Pu inventories of 45 and ∼55 Bq m−2 agree well with that expected from global fallout. The 240Pu/239Pu atom ratios in the soil ranged from 0.172 to 0.220. The ratios are similar to typical global fallout values. Hence, any close-in fallout contribution from the Chinese nuclear weapons tests, mainly conducted in the 1970s, must have either been negligible or had a similar 240Pu/239Pu ratio to that of global fallout. The top 10 cm layer of the soil contributes ∼90% of the total inventory and the maximum concentrations appeared in the 2-4 cm or 4-6 cm layers. It is suggested that climatic conditions and organic content are the two main factors that affect the vertical migration of plutonium in soil. 相似文献
6.
Study of metabolites from the degradation of polycyclic aromatic hydrocarbons (PAHs) by bacterial consortium enriched from mangrove sediments 总被引:3,自引:0,他引:3
The PAH metabolites produced during degradation of fluorene, phenanthrene and pyrene by a bacterial consortium enriched from mangrove sediments were analyzed using the on-fiber silylation solid-phase microextraction (SPME) combining with gas chromatography–mass spectrometry (GC–MS) method. Seventeen metabolites at trace levels were identified in different PAH degradation cultures based on the full scan mass spectra. In fluorene degradation cultures, 1-, 2-, 3- and 9-hydroxyfluorene, fluorenone, and phthalic acid were detected. In phenanthrene and pyrene degradation cultures, various common metabolites such as phenanthrene and pyrene dihydrodiols, mono-hydroxy phenanthrene, dihydroxy pyrene, lactone and 4-hydroxyphenanthrene, methyl ester, and phthalic acid were found. The detection of various common and novel metabolites demonstrates that SPME combining with GC–MS is a quick and convenient method for identification as well as monitoring the real time changes of metabolite concentrations throughout the degradation processes. The knowledge of PAH metabolic pathways and kinetics within indigenous bacterial consortium enriched from mangrove sediments contributes to enhance the bioremediation efficiency of PAH in real environment. 相似文献
7.
Cheryl L. Dahlin Connie A. Williamson W. Keith Collins David C. Dahlin 《Environmental Forensics》2013,14(2):191-201
The applicability of sequential extraction as a means to determine species of heavy-metals was examined by a study on soil samples from two Superfund sites: the National Lead Company site in Pedricktown, NJ, and the Roebling Steel, Inc., site in Florence, NJ. Data from a standard sequential extraction procedure were compared to those from a comprehensive study that combined optical- and scanning-electron microscopy, X-ray diffraction, and chemical analyses. The study shows that larger particles of contaminants, encapsulated contaminants, and/or man-made materials such as slags, coke, metals, and plastics are subject to incasement, non-selectivity, and redistribution in the sequential extraction process. The results indicate that standard sequential extraction procedures that were developed for characterizing species of contaminants in river sediments may be unsuitable for stand-alone determinative evaluations of contaminant species in industrial-site materials. However, if employed as part of a comprehensive, site-specific characterization study, sequential extraction could be a very useful tool. 相似文献
8.
M. Reza Ghanbarpour Keith William Hipel 《Environment, Development and Sustainability》2009,11(2):241-253
Environmental disputes arise due to opposing views of various groups about their environmental concerns and their economic
or developmental interests. Development and protection of the environment constitute two main contradictory objectives within
the sustainable development paradigm, which are often in conflict. The decision support system, GMCR II, which implements
the graph model for conflict resolution, is employed to model and analyze an environmental dispute arising over the construction
of a new freeway between the Iranian capital, Tehran, and the city of Chalous located in the north of the country. This study
demonstrates that the graph model for conflict resolution can be used as a methodology to promote a reasonable balance between
economic development and environmental protection from a strategic viewpoint. In addition to systematically modelling the
conflict by putting the existing information into proper perspective, it is shown how conflict analysis can be used for comparing
alternative scenarios and predicting possible future outcomes.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
9.
Janani Vivekananda Janpeter Schilling Shreya Mitra Nisha Pandey 《Environment, Development and Sustainability》2014,16(6):1141-1161
Bangladesh and India are among the world’s most populous but also most vulnerable countries to environmental risks. In addition to storms, sea-level rise, floods and droughts, local communities face a multitude of pre-existing and concomitant economic and socio-political risks. To understand these risks and how communities respond to them is critical in securing community livelihoods. We therefore ask what are the livelihood risks; how do they impact the human security of environment sensitive communities in Satkhira, Bangladesh and in Odisha, India; and, what are the responses of these communities to the livelihood risks? The communities studied in Bangladesh depend mainly on the shrimp and fish resources of the Sundarbans mangrove forest. The two communities researched at Lake Chilika in India depend on fishing and salt farming, respectively. The field research, conducted in 2012 and 2013, shows that the communities face multiple and interacting livelihood risks. While storms and floods are common environmental risks in both countries, related livelihood risks are case-specific. In Bangladesh, attacks by criminals are the major threat to human well-being, while in India, it is violent conflict between lake users. Unsustainable resource extraction is found in both study countries. In Bangladesh, shrimp farming weakens the flood protection, while in India, illegal prawn farming marginalizes poorer lake users. Accessing loans and labor migration are responses observed in both countries. We conclude that adaptation to environmental changes needs to be sensitive to the interaction between governance, local institutions and socio-economic developments. 相似文献
10.
Association of plutonium with sediments from the Ob and Yenisey Rivers and Estuaries 总被引:1,自引:0,他引:1
Lindis Skipperud Justin Brown L. Keith Fifield Deborah H. Oughton Brit Salbu 《Journal of environmental radioactivity》2009
The present study applied sequential extraction techniques to investigate the binding and mobility of plutonium (Pu) in sediments from the rivers and estuaries of the Ob and Yenisey. As a study site, the Ob and Yenisey are particularly interesting as both rivers have weapons-grade Pu sources in their catchment areas, including the Russian Pu production and reprocessing plants at Mayak, Tomsk-7 and Krashnoyarsk, and the Semipalantinsk nuclear weapons testing site in Kazakhstan. Plutonium activity and 240Pu/239Pu ratios were determined using accelerator mass spectrometry (AMS). Sequential extractions showed that between 47 and 80% of the Pu in Yenisey River sediments and 35–53% of the Pu in soils around the Techa River are mobilized with weak oxidising agents, which can indicate that Pu is bound to organic material. In contrast, Pu in Ob and Yenisey Estuarine sediments was more strongly bound, with 60–100% being found in the HNO3-extractable fraction. This change in speciation could reflect either that Pu bound to organic material in the Techa and Yenisey River sediments becomes more fixed to the sediments with time, or that organic-bound Pu is mobilized and released to the water when the sediments encounter the more saline water of the Ob and Yenisey estuaries. In general, 240Pu/239Pu ratios were relatively consistent between different extraction fractions, although, in whole sediments, an increase in ratio was observed with distance from the source. This reflects the increased influence of weapon fallout from catchment runoff within the river systems, as compared to the weapons-grade sources close to the production and reprocessing plants. Knowledge of Pu speciation in the Ob and Yenisey Rivers, and the processes controlling its behaviour in estuarine systems, can improve predictions of its transfer and subsequent environmental impact to Arctic Seas. 相似文献