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71.
72.
本文对西昌市大气污染现状进行调查分析,揭示了大气环境污染的特征及其变化规律,从宏观上提出了保护大气环境的对策。 相似文献
73.
石油工业废弃物处置及其生物治理趋势 总被引:4,自引:0,他引:4
鉴于我国石油工作者对石油工业废弃物的普遍关注,现在介绍生物治理的基本概念及SPE石油工程师协会中有关含油污泥生物处置的途径及其突出优越性。生物液/固处理工艺(LST)是目前含油污泥处置现场最经济可行的处置方案。这种好氧的LST工艺过程,能够比较充分地代谢和降解石油污泥中的油和脂并大量除去多环芳烃类(PAH)化合物及其它有机化合物,明显地降低了石油废弃物对人、畜的毒害程度。其工艺较简单,操作也简易,凡经此工艺处理后的废弃物不留残毒和后患,因此早已被世界上先进国家的炼油业视为处理含油污泥的有效选择了。石油工业废弃物的生物防治和生物降解工艺较大程度地领先于目前我国现场正在执行的各种处理含油废弃物的处理工艺。 相似文献
74.
Barry A. Pierce 《Environmental management》1983,7(2):151-160
Grass carp (Ctenopharyngodon idella Val.) were introduced into the United States in 1963 as potential biological control agents for nuisance aquatic weeds. Since that time an oftentimes bitter controversy has raged over its effects on sportfishing, and its possible natural reproduction and naturalization in North America. This review considers the history, ecology, and present status of grass carp in the United States in light of the voluminous scientific research conducted since its importation. Particular attention is given to the role of grass carp in the fisheries management plans of Arkansas. Recent development of a sterile, triploid grass carp hybrid may lead to widespread use of grass carp to control nuisance aquatic weeds in culturally eutrophicated waters of the United States. 相似文献
75.
A variety of novel polymeric materials ranging from elastomers to tough, rigid plastics have been prepared by the cationic copolymerization of regular soybean oil, low-saturation soybean oil, or conjugated low-saturation soybean oil with various alkene commonomers. Using appropriate compositions and reaction conditions, 70–100% of the soybean oil is covalently incorporated into the cross-linked polymer networks, contributing significantly to cross-linking during copolymerization. The resulting thermosets exhibit thermophysical and mechanical properties that are competitive with those of their petroleum-based counterparts. In addition, good damping and shape memory properties have been obtained by controlling the degree of cross-linking and the rigidity of the polymer backbone. New materials with similar characteristics have also been produced from other biological oils, including tung, and fish oils using the same technique. The new, more valuable properties of these bioplastics suggest numerous promising applications of these novel polymeric materials. 相似文献
76.
Melinda G. Knutson Donald J. Leopold Richard C. Smardon 《Environmental management》1993,17(2):199-210
Consideration of biological quality has long been an important component of rating areas for conservation. Often these same
areas are highly valued by people for aesthetic reasons, creating demands for housing and recreation that may conflict with
protection plans for these habitats. Most methods of selecting land for conservation purposes use biological factors alone.
For some land areas, analysis of aesthetic qualities is also important in describing the scenic value of undisturbed land.
A method for prioritizing small islands and shoals based on both biological and visual quality factors is presented here.
The study included 169 undeveloped islands and shoals ⩽0.8 ha in the Thousand Islands Region of the St. Lawrence River, New
York. Criteria such as critical habitat for uncommon plant and animal species were considered together with visual quality
and incorporated into a rating system that ranked the islands and shoals according to their priority for conservation management
and protection from development. Biological factors were determined based on previous research and a field survey. Visual
quality was determined by visual diagnostic criteria developed from public responses to photographs of a sample of islands.
Variables such as elevation, soil depth, and type of plant community can be used to classify islands into different categories
of visual quality but are unsuccessful in classifying islands into categories of overall biological quality. 相似文献
77.
Assessing Biological Integrity Using Freshwater Fish and Decapod Habitat Selection Functions 总被引:2,自引:0,他引:2
Comparison between the number of taxa observed and the number expected in the absence of human impact is an easily understood and ecologically meaningful measure of biological integrity. This approach has been successfully applied to the assessment of the biological quality of flowing water sites using macroinvertebrates with the river invertebrate and classification system (RIVPACS) and its derivatives. In this paper, we develop a method similar to the RIVPACS predictive model approach to assess biological integrity at flowing-water sites using freshwater fish and decapod assemblages. We extend the RIVPACS approach by avoiding the biotic classification step and model each of the individual species separately. These assemblages were sampled at 118 least impacted (reference) sites in the Auckland region, New Zealand. Individual discriminant models based on the presence or absence of the 12 most common fish and decapod species were developed. Using the models, predictions were made using environmental measures at new sites to yield the probability of the capture of each of the 12 species, and these were combined to predict the assemblage expected at sites. The expected assemblage was compared to that observed using an observed over expected ratio (O/E). The models were evaluated using a number of internal tests including jackknifing, data partitioning, and the degree to which O/E values differed between reference sites and a set of sites perceived to be impaired by human impacts. 相似文献
78.
This paper sheds light on changing farmers' land management practices in two mountain watersheds, with and without external
assistance, in the western hills of Nepal. Information used in the analysis were obtained through a survey of 300 households,
group discussion, key informant interviews, and field observation conducted during April–September 1999. Confronted with ever-decreasing
landholding size due to a steadily growing population and scarcity of nonfarming employment opportunities, farmers in both
watersheds have increasingly adopted assorted types of structural and biological measures to control soil erosion, landslides,
gully expansion, and soil nutrient loss to maintain or even enhance land productivity. Adoption of gully control measures,
construction of the retention walls, alley cropping, use of vegetative measures for landslide control, mulching, and use of
green manure and chemical fertilizers are found significantly high in the project area due to the provision of technical and
financial support, whereas composting is found significantly high in the nonproject area. Different from the traditionally
held beliefs, population pressure on a finite land resource has brought positive change in land management. However, the experience
from both watersheds indicates that there is limit to the extent that resource poor farmers can respond to land degradation
without any external assistance. Required is the arrangement for appropriate polices and support services and facilities enabling
farmers to adopt locationally suitable and economically attractive land management technologies. 相似文献
79.
Stream Invertebrate Communities, Water Quality, and Land-Use Patterns in an Agricultural Drainage Basin of Northeastern Nebraska, USA 总被引:2,自引:0,他引:2
We used invertebrate bioassessment, habitat analysis, geographic information system analysis of land use, and water chemistry
monitoring to evaluate tributaries of a degraded northeast Nebraska, USA, reservoir. Bimonthly invertebrate collections and
monthly water chemistry samples were collected for two years on six stream reaches to identify sources contributing to reservoir
degradation and test suitability of standard rapid bioassessment methods in this region. A composite biotic index composed
of seven commonly used metrics was effective for distinguishing between differentially impacted sites and responded to a variety
of disturbances. Individual metrics varied greatly in precision and ability to discriminate between relatively impacted and
unimpacted stream reaches. A modified Hilsenhoff index showed the highest precision (reference site CV = 0.08) but was least
effective at discriminating among sites. Percent dominance and the EPT (number of Ephemeroptera, Plecoptera, and Trichoptera
taxa) metrics were most effective at discriminating between sites and exhibited intermediate precision. A trend of higher
biotic integrity during summer was evident, indicating seasonal corrections should differ from other regions. Poor correlations
were evident between water chemistry variables and bioassessment results. However, land-use factors, particularly within 18-m
riparian zones, were correlated with bioassessment scores. For example, there was a strong negative correlation between percentage
of rangeland in 18-m riparian zones and percentage of dominance in streams (r
2
= 0.90, P < 0.01). Results demonstrate that standard rapid bioassessment methods, with some modifications, are effective for use in this agricultural
region of the Great Plains and that riparian land use may be the best predictor of stream biotic integrity. 相似文献
80.