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141.
Meinardus HW Dwarakanath V Ewing J Hirasaki GJ Jackson RE Jin M Ginn JS Londergan JT Miller CA Pope GA 《Journal of contaminant hydrology》2002,54(3-4):173-193
Over the last few years, more than 40 partitioning interwell tracer tests (PITTs) have been conducted at many different sites to measure nonaqueous phase liquid (NAPL) saturations in the subsurface. While the main goal of these PITTs was to estimate the NAPL volume in the subsurface, some were specifically conducted to assess the performance of remedial actions involving NAPL removal. In this paper, we present a quantitative approach to assess the performance of remedial actions to recover NAPL that can be used to assess any NAPL removal technology. It combines the use of PITTs (to estimate the NAPL volume in the swept pore volume between injection and extraction wells of a test area) with the use of several cores to determine the vertical NAPL distribution in the subsurface. We illustrate the effectiveness of such an approach by assessing the performance of a surfactant/foam flood conducted at Hill Air Force Base, UT, to remove a TCE-rich NAPL from alluvium with permeability contrasts as high as one order of magnitude. In addition, we compare the NAPL volumes determined by the PITTs with volumes estimated through geostatistical interpolation of aquifer sediment core data collected with a vertical frequency of 5-10 cm and a lateral borehole spacing of 0.15 m. We demonstrate the use of several innovations including the explicit estimation of not only the errors associated with NAPL volumes and saturations derived from PITTs but also the heterogeneity of the aquifer sediments based upon permeability estimates. Most importantly, we demonstrate the reliability of the 相似文献
142.
Decadal changes in a NW Mediterranean Sea food web in relation to fishing exploitation 总被引:1,自引:0,他引:1
We analysed changes in the ecological roles of species, trophic structure and ecosystem functioning using four standardized mass-balance models of the South Catalan Sea (North-western Mediterranean). Models represented the ecosystem during the late 1970s, mid 1990s, early 2000s, and a simulated no-fishing scenario. The underlying hypothesis was that ecosystem models should quantitatively capture the increasing exploitation in the ecosystem from the 1970s to 2000s, as well as differences between the exploited and non-exploited scenarios. Biomass showed a general decrease, while there was an increase in biomass at lower trophic levels (TL) from the 1970s to 2000s. The efficiency of energy transfer (TE) from lower to higher TLs significantly increased with time. The ecosystem during the 1990s showed higher biomass and flows than during the 1970s and 2000s due to an increase in small pelagic fish biomass (especially sardines). Exploited food webs also showed similarities in terms of general structure and functioning due to high intensity of fishing already in the 1970s. This intensity was highlighted with low trophic levels in the catch, high consumption of production by fisheries, medium to high primary production required to sustain the catches and high losses in secondary production due to fishing. Significant differences on ecosystem structure and functioning were highlighted between the exploited and no-fishing scenarios. Biomass of higher TLs increased under the no-fishing scenario and the mean trophic level of the community and the fish/invertebrate biomass ratios were substantially lower in exploited food webs. The efficiency of energy transfer (TE) from lower to higher TLs was lower under the no-fishing scenario, and it showed a continuous decrease with increasing TL. Marine mammals, large hake, anglerfish and large pelagic fish were identified as keystone species of the ecosystem when there was no fishing, while their ecological importance notably decreased under the exploited periods. On the contrary, the importance of small-sized organisms such as benthic invertebrates and small pelagic fish was higher in exploited food webs. 相似文献
143.
福州国家森林公园游客游览状况与其心理健康的关系 总被引:2,自引:0,他引:2
以福州国家森林公园为例,调查了公园游客在游览中的偏好和习惯,并结合其心境状况指标(POMS),分析了不同游览偏好与心境状况的关系。结果表明:超过60%的游客喜欢在春季游览森林公园;至少每月游览1~2次对身心健康有益,且每次游览的时间至少在2h以上为最佳;居住地距离福州国家森林公园0.5km以内的游客,心理健康状况显著优于距离0.5km以上的游客;愿意游览森林公园的游客其心理健康状况显著优于不愿意或无所谓的游客。最后,根据调查结果,对游客使用森林公园的方式以及公园管理等方面提出了建议。 相似文献
144.
Sandra S. Embrey 《Journal of the American Water Resources Association》2001,37(2):407-421
ABSTRACT: Fecal coliforms, Escherichia coli, enterococci, and somatic coliphages were detected in samples from 31 sites on streams draining urban and agricultural regions of the Puget Sound Basin Lowlands. Densities of bacteria in 48 and 71 percent of the samples exceeded U.S. Environmental Protection Agency's freshwater recreation criteria for Escherichia coli and enterococci, respectively, and 81 percent exceeded Washington State fecal coliform standards. Male‐specific coliphages were detected in samples from 15 sites. Male‐specific F+RNA coliphages isolated from samples taken at South Fork Thornton and Longfellow Creeks were serotyped as Group II, implicating humans as potential contaminant sources. These two sites are located in residential, urban areas. F+RNA coliphages in samples from 10 other sites, mostly in agricultural or rural areas, were serotyped as Group I, implicating non‐human animals as likely sources. Chemicals common to wastewater, including fecal sterols, were detected in samples from several urban streams, and also implicate humans, at least in part, as possible sources of fecal bacteria and viruses to the streams. 相似文献
145.
Environmental, biological, socio-cultural and economic variations in the Himalayas have led to the evolution of diverse and unique traditional agroecosystems, crop species, and livestock, which help the traditional mountain farming societies to sustain themselves. During the recent past, as a result of rapid changes in land use caused by socio-cultural and economic changes and various environmental perturbations, the agrobiodiversity of the Central Himalayan agroecosystems has changed steadily. A recent survey conducted in 150 different villages located along an elevated transect of the Alaknanda catchment of the Central Himalaya revealed that over a period of two decades (1970–74 and 1990–94) the cultivated area under many traditional crops had declined significantly. A micro-level study carried out in 30 villages revealed that a series of changes had occurred in land use practices over a period of 25–30 years.The loss of agrobiodiversity and the changing socio-cultural and economic dimensions and their impacts on the sustainability of Himalayan agroecosystems are emerging as major causes of concern at local/regional/national scale, and appropriate options to meet these challenges are discussed in this paper. 相似文献
146.
Validity of Performance Criteria and a Tentative Model for Regulatory Use in Compensatory Wetland Mitigation Permitting 总被引:1,自引:1,他引:0
The purpose of this paper is to develop the principles for a manageable and practical set of performance criteria that will
reasonably assure no net loss in a situation in which it cannot be absolutely assured. To this end, the performance criteria
proposed for 116 compensatory wetland projects on file with the Army Corps of Engineers in San Francisco, between 1988 and
1995, were examined. The trends discerned in the project proposals were analyzed and evaluated in light of the current state
of wetland science. Specific suggestions for the development of uniform criteria in each of four major wetland types—riparian,
perennial tidal, perennial nontidal, and seasonal—are discussed, and a system of regulation tying qualitative assessment with
quantitative requirements is outlined as a reasonable solution to the enforcement of the no-net-loss policy. 相似文献
147.
Peter J. Peterson W. Peter Williams 《Environmental science and pollution research international》1999,6(4):225-232
Measurements of urban air quality at monitoring stations in developed countries have frequently involved the criteria gaseous
pollutants, particulates, hazardous air pollutants, perceived air quality and relevant meteorological conditions. Large numbers
of indicators have therefore been established to quantify emissions, concentrations and environmental and human health impacts
of each of these groups of substances. To simplify the data for management, several indicators have been grouped together
to form urban air quality indices but the weightings of individual variables is contentious.
In industrialising and developing countries, data may be limited and traditional air pollutant indicators cannot often be
constructed. The emphasis therefore has to be placed on the development of policy-relevant indicators, such as Response Indicators
that reflect different policy principles for regulating air pollutant emissions. Indices that quantify the air quality management
capabilities and capacities at the city level provide further useful decision-relevant tools. Four sets of indices, namely,
1. air quality measurement capacity, 2. data assessment and availability, 3. emissions estimates, and 4. management enabling
capabilities, and a composite index to evaluate air quality management capability, were constructed and applied to 80 cities.
The indices revealed that management capability varied widely between the cities. In some of the cities, existing national
knowledge on urban air quality could have been more effectively used for management.
It was concluded that for effective urban air quality management, a greater emphasis should be given, not just to monitoring
and data capture programmes, but to the development of indicators and indices that empower decision-makers to initiate management
response strategies. Over-reliance on restricted, predetermined sets of traditional air quality indicators should be avoided. 相似文献
148.
149.
为独立评估环境空气连续自动监测系统运维质量,掌握环境空气监测数据准确性等信息,我国开展了环境空气连续自动监测系统性能审核工作,通过分析影响审核结果的相关因素,提出,性能审核标准气体浓度应接近实际监测空气中的气体浓度,性能审核时间的选择应满足《环境空气质量标准》(GB 3095—2012)中数据统计的有效性规定,性能审核气体压力应保持恒定并接近实际采样时的气压,标准气体进样方式应通过日常采样管路等,从而进一步提高性能审核结果的科学性和准确性,为生态环境管理部门了解环境空气数据质量提供坚实基础。 相似文献
150.