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991.
This paper reviews a series of strategies for improving environmental performance in the small-scale gold mining industry.
Although conditions vary regionally, few regulations and policies exist specifically for small-scale gold mining activity.
Furthermore, because environmental awareness is low in most developing countries, sites typically feature rudimentary technologies
and poor management practices. A combination of policy-, managerial- and technology-related initiatives is needed to facilitate
environmental improvement in the industry. Following a broad overview of these initiatives, a recommended strategy is put
forth for governments keen on improving the environmental conditions of resident small-scale gold mines. 相似文献
992.
Isla Victoria (Nahuel Huapi National Park, Argentina), a large island dominated by native Nothofagus and Austrocedrus forest, has old plantations of many introduced tree species, some of which are famed invaders of native ecosystems elsewhere.
There are also large populations of introduced deer and shrubs that may interact in a complex way with the introduced trees,
as well as a recently arrived population of wild boar. Long-standing concern that the introduced trees will invade and transform
native forest may be unwarranted, as there is little evidence of progressive invasion, even close to the plantations, despite
over 50 years of opportunity. Introduced and native shrubs allow scattered introduced trees to achieve substantial size in
abandoned pastures, but in almost all areas neither the trees nor the shrubs appear to be spreading beyond these sites. These
shrub communities may be stable rather than successional, but the technology for restoring them to native forest is uncertain
and probably currently impractical. Any attempt to remove the exotic tree seedlings and saplings from native forest would
probably create the very conditions that would favor colonization by exotic plants rather than native trees, while simply
clear-cutting the plantations would be unlikely to lead to regeneration of Nothofagus or Austrocedrus. The key to maintaining native forest is preventing catastrophic fire, as several introduced trees and shrubs would be favored
over native dominant trees in recolonization. Deer undoubtedly interact with both native and introduced trees and shrubs,
but their net effect on native forest is not yet clear, and specific management of deer beyond the current hunting by staff
is unwarranted, at least if preventing tree invasion is the goal. The steep terrain and shallow soil make the recently arrived
boar a grave threat to the native forest. Eradication is probably feasible and should be attempted quickly. 相似文献
993.
Modeling of air pollutant dispersion has been undertaken for emissions of sulfur dioxide (SO2) at the Mina Al-Fahal refinery in the Sultanate of Oman. The study was conducted during the period of November 1999 to October
2000. The Industrial Source Complex Short-Term (ISCST32) air pollution model was adopted to predict the ground level concentration
of SO2 in and around the refinery. The modeling results were validated against measured data during the study period. The comparison,
based on the monthly average measurements, showed that the model underestimates the observed SO2 concentrations. However, the predicted ground level concentrations of SO2 during the months of September, October, November, and June were in better agreement with the observations. The predicted
SO2 values are presented in the form of concentration contours to determine the spatial distribution of SO2 and to assess the impact on air quality over the survey area. Predicted SO2 concentrations were found lower than the World Health Organisation (WHO) guideline value of 365 μg/m3, with the maximum ground level concentrations being found to occur relatively close to the sources of emission. Moreover,
concentration contour patterns for the modeled area vary with changes in meteorological conditions. On the basis of this study,
the refinery is not likely to cause any significant deterioration in air quality, and predicted concentrations of SO2 are well below those likely to influence health. 相似文献
994.
Robert M GarrettStephen J Rothenburger Roger C Prince 《Spill Science & Technology Bulletin》2003,8(3):297-302
The aerobic biodegradation of the components of a fuel oil under Arctic summer conditions follows a pattern that is indistinguishable from that exhibited under temperate conditions. Straight chain alkanes and small aromatics are degraded first, followed by branched alkanes and larger and alkylated aromatics. We present data on the biodegradation of heptadecane as a representative n-alkane, pristane as a representative iso-alkane, and naphthalene, phenanthrene, and chrysene and their alkylated forms as representative two-, three- and four-ring aromatic hydrocarbons. In particular, the pattern of degradation of the alkylated aromatics allows the identification of biodegradation in samples collected from the field and the estimation of the extent of biodegradation that occurred in the In-Situ Treatment of Oiled Sediment Shorelines Field Trials. 相似文献
995.
GONTRAN F. BAGE RÉJEAN SAMSON BERNARD SINCLAIR-DESGAGNÉ 《Environmental management》2002,30(6):0807-0815
A technicoeconomic model is developed to select an optimal strategy for the remediation of a contaminated site and to determine
the value of this remediation strategy. The model is an extension of actual cost–benefit analysis, with consideration of “irreversible”
remediation technology choices, technology effectiveness, and uncertainty on the site's level of contamination. The model
considers the possibility of reducing uncertainty by both acquiring more and better information on the level of contamination
and by offering the decision-maker the opportunity to reevaluate his decision and switch to a more appropriate technology.
It is believed that this model will help decision-makers in the selection of a remediation strategy by presenting all potentially
feasible strategies, and how uncertainty on the site's level of contamination affects these strategies. 相似文献
996.
Commercial Medicinal Plant Extraction in the Hills of Nepal: Local Management System and Ecological Sustainability 总被引:1,自引:0,他引:1
Helle Overgaard Larsen 《Environmental management》2002,29(1):88-101
This paper presents a case study from Jumla District, Nepal, investigating local management systems and ecological sustainability
of commercial collection of a medicinal plant, spikenard (Nardostachys grandiflora DC, Valerianaceae), growing in alpine meadows. Interviews were undertaken with local collectors, traders, and district forest
office staff, and the dynamics of people–plant interactions are analyzed using the Oakerson model. In all, 110 sample plots
1m square were laid out in three areas with differing collection and grazing pressures for recording of floristic composition
and abundance of spikenard root biomass. Comparisons show significantly more root biomass in uncollected than collected areas
with local management and the interpretation of differences in abundance is discussed. The combination of qualitative and
quantitative investigations can provide a framework for the study of people–plant interactions, and this study can serve as
first step in a compilation of cases to create a more detailed picture of local management systems of Nepali nontimber forest
products in general and commercially collected medicinal and aromatic plants in particular. 相似文献
997.
Use of Life Cycle Assessment in Environmental Management 总被引:11,自引:0,他引:11
The aim of this paper is to demonstrate how life cycle assessment (LCA) can be used to develop strategic policies that can
lead to a minimization of the environmental burden resulting from the provision of services or the manufacture, use, and disposal
of products within the economy. We accomplish this aim by presenting a case study that evaluates the greenhouse gas contributions
of each stage in the life cycle of containerboard packaging and the potential impact on emissions of various policy options
available to decision-makers.
Our analysis showed that, in general, the most useful strategy was to recycle the used packaging. However, our analysis also
indicated that when measures are taken to eliminate sources of methane emissions, then recycling is no longer beneficial from
a greenhouse perspective. This is because the process energy required in the form of gas and electricity is substantially
greater for containerboard manufactured from recycled material than it is for virgin fiber. 相似文献
998.
Human (managerial) actions affect the survival probabilities of the keystone species of an ecological–economic system. In turn, the well-being of these keystone species translates into the well-being or the resilience of the underlying ecological–economic system. What are the theoretical connections between human actions, keystone species survival, and the resilience of ecological–economic systems? In this note, we construct a simple stochastic model to draw out the links between this trinity. 相似文献
999.
通过各种乳化剂、增稠剂、稳定剂种类及量的复配实验表明,涂抹性能与屈服应力有显著负相关。回归方程分析表明,0 47%复合乳化剂(HLB=6 92)、0 57%羧甲基纤维素钠(CMC-Na)、0 13%琼脂(Agar)能使制品有较好的涂抹性能,加入0 3%黄原胶,可以提高制品的热稳定性。 相似文献
1000.
In Europe targets have been laid down by EU legislation for the recycling rate of end-of-life vehicles to be achieved within the nearby future. It is illustrated in this paper that the definition of the recycling rate and the realisation of the imposed targets are very much dependent on different parameters such as the changing lifetime of the product and product design. It may seem obvious that the recycling rate is determined by various time-varying factors, however, this paper endeavours to describe and quantify the role of these factors on the recycling rate over time by the use of a dynamic systems model. This model permits the prediction of the recycling rate as a function of the numerous presented parameters, changing design scenarios etc. In addition, different definitions of the recycling rate will be presented and discussed. This will lead to a better understanding of the parameters affecting the recycling system and a more precise understanding of the recycling targets and their realisation as imposed by EU legislation. This paper focuses on cars, but the discussion and the definitions derived are equally valid for any end-of-life product. 相似文献