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411.
A total of 154 aquatic alien species have invaded the New York State Canal and Hudson River systems and a total of 162 aquatic species have invaded the Great Lakes Basin. Some of these invasive species are causing significant damage and control costs in both aquatic ecosystems. In the New York State Canal and Hudson River systems, the nonindigenous species are causing an estimated 500 million dollars in economic losses each year. The economic and environmental situation in the Great Lakes Basin is far more serious from nonindigenous species, with losses estimated to be about 5.7 billion dollars per year. Commercial and sport fishing suffer the most from the biological invasions, with about 400 million dollars in losses reported for the New York State Canal and Hudson River systems and 4.5 billion dollars in losses reported for the Great Lakes Basin.  相似文献   
412.
ABSTRACT: Associations between the El Nino Southern Oscillation (ENSO) climate pattern and temporal variability in flow and 12 water quality variables were assessed at 77 river sites throughout New Zealand over a 13‐year period (1989 through 2001). Trends in water quality were determined for the same period. All 13 variables showed statistically significant linear regression relationships with values of the Southern Oscillation Index (SOI). The strongest relationships were for water temperature (mean R2= 0.20), dissolved reactive phosphorus (0.18), and oxidized nitrogen (0.17). The association with SOI varied by climate region. The observed patterns were generally consistent with known ENSO effects on New Zealand rainfall and air temperature. Trends in water quality variables for the periods 1989 through 1993, 1994 through 1998, and 1989 through 1998 were reasonably consistent with trends in SOI, even when the influence of river flow was removed from the data. This suggests that SOI effects on water quality are not necessarily a direct consequence of changes in flow associated with rainfall variation. In addition, both Baseline (32 upstream) and Impact (45 downstream) sites showed similar trends, indicating that changes in management were not directly responsible. We conclude that interpretation of long term water quality datasets in rivers requires that climate variability be fully acknowledged and dealt with explicitly in trend analyses.  相似文献   
413.
ABSTRACT: Most studies of nutrient loss from small study watersheds ignore a potentially important loss transported by the suspended sediment load. We proposed that the geology and vegetation of a watershed are predictors of the nutrient and heavy metal transporting capacity of its suspended sediment. Analyses of acid-digestable and extractable nutrients showed differences for sediments derived from ponderosa pine forests in the Southwest on different geologies. These differences were similar for soil, stream bank, and stream channel material for a given site. Suspended sediment collections had nutrient concentrations similar to those of stream channel collections. Different vegetation on a given geology affected primarily the organic matter content, cation exchange capacity, total P, and levels of extractable nutrients in sediment.  相似文献   
414.
ABSTRACT: A growing number of developing communities in New Jersey is planning for an ultimate population that would be supplied by endogenous sources of water. At the state and national level, however, reliance on exogenous sources appears to be in favor. Both viewpoints, of course, recognize that water supply is one of the major critical factors in determining the capacity of a land area to support population. Three planning issues that bear on this endogenous-exogenous source controversy are discussed: 1) deep aquifers which have recharge areas in other political jurisdictions and are therefore regulated by other bodies will not count as an endogenous source, reliance will be placed only on shallow water table aquifers which are recharged by local precipitation; 2) total development of the groundwater resources of a headwaters community could result in severe base flow diminishment, thereby supporting the notion that these communities have a regional responsibility to restrict their growth so as to preserve and protect the water supply for downstream users; and 3) yield decrementing estimates, i.e., how much recharge water is lost to runoff as a consequence of development, are needed in order to assess the magnitude of local water resources.  相似文献   
415.
ABSTRACT: A basic problem in the management of rivers has been how to balance the tradeoffs between instream and out-of-stream uses. Traditionally, the problem has been addressed by optimizing the economic benefits of flow diversions and regulated releases with instream uses as a flow constraint. An alternative method is to model the effect different river flows have on various recreational uses (e.g., boating, fishing) and then use the results as an additional function or piece of information to determine river project operations and benefits. A methodology that is based on multiobjective decision theory and that relates instream recreational preferences to river flow is proposed. The methodology consists of determining, standardizing, and combining recreational benefit functions, and incorporating potential sources of uncertainty into an estimate of total instream benefits. Thus different types of flow patterns, resulting from reservoir regulation (out-of-stream water uses), can be analyzed to determine their potential instream impact. The methodology is applied to the New River Gorge, West Virginia, which has been designated as a National River.  相似文献   
416.
ABSTRACT: Experimental cuttings on two small, hardwood-forested watersheds in New England showed that annual streamflow can be increased as much as 41 percent. Most of the increase occurred in summer and early autumn when additional streamflow is most needed. Revegetation caused the annual increases to nearly disappear within 4 years after complete forest clearing.  相似文献   
417.
418.
新世纪企业环境战略研究   总被引:1,自引:1,他引:1  
汪勇  裴洪平 《重庆环境科学》2002,24(2):14-16,20
介绍了环境营销的定义,开展环境营销的必要性及其给企业和社会带来的好处,指出在新世纪,为了实现可持续发展,企业不仅要做好自身的污染防治工作,更应变被动为主动,选择环境营销导向,从战略的高度来审视企业的环境活动和行为,并对企业进行重新组织,同时本文还对企业建立环境营销战略的具体环境行为作了进一步探讨。  相似文献   
419.
介绍了在自动化综合体上精锻汽车后桥壳轴颈的新工艺和综合体的结构.该工艺可显著降低产品成本,节省材料.  相似文献   
420.
武汉东湖新技术开发区是首批国家新技术产业开发区之一,为了促进开发区的环境与经济的协调发展,加强东湖新技术开发区的环境保护,笔者对东湖新技术开发区环境质量现状进行了调查研究,初步摸清了该区域环境质量状况,指出了目前开发区建设中应重视的环境管理问题,并对开发区的环境保护提出了一些建议,该项研究具有明显的社会和环境效益,对改善武汉市是东湖开发区的投资环境,提高人民生活水平和质量,树立城市新形象有着重要的现实意义。  相似文献   
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