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421.
Pimentel D 《Environmental management》2005,35(5):692-702
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
422.
Mike R. Scarsbrook Chris G. McBride Graham B. McBride Graham G. Bryers 《Journal of the American Water Resources Association》2003,39(6):1435-1447
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
423.
James R. Gosz Carleton S. White Peter F. Ffolliott 《Journal of the American Water Resources Association》1980,16(5):927-933
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
424.
Robert M. Hordon 《Journal of the American Water Resources Association》1977,13(5):933-939
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
425.
Marshall Flug Robert H. Montgomeiy 《Journal of the American Water Resources Association》1988,24(5):1073-1081
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
426.
James W. Hornbeck 《Journal of the American Water Resources Association》1975,11(6):1257-1260
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
427.
428.
New technologies are characterized by various forms of incertitude that challenge both scientific expertise and regulatory action. In this paper, we argue that these incertitudes place experts in irreducible double bind situations, which may end in paralysis. Double binds emerge when primary injunctions are contradicted by secondary injunctions at a different logical level, which affects the interpretation of the primary injunction. Adequately addressing the challenges posed by new technologies requires phronesis, or pragmatic, context-dependent and action-oriented knowledge grounded in value deliberation. Using endocrine disruptors and carbon nanotubes as empirical examples, we argue that in relation to new technologies involving various kinds of incertitude, being phronimos—the person who can do phronesis—involves synthetically and simultaneously enacting parts of the three interrelated domains of knowledge, ethics and institutions, also across different logical levels. The special kind of experience-based phronesic skill that required in the regulatory appraisal of new technologies is thus fundamentally related to the human capacity of pattern recognition. Finally, we argue that being aware of and making full use of practical wisdom thus conceptualized enables a new operationalization of the precautionary principle. 相似文献
429.
新国家排放标准的实施对燃煤锅炉二氧化硫和氮氧化物排放提出了严格的要求,目前单一的减排技术只能满足部分燃煤锅炉的排放要求。本文综述了国内外现有的脱硫和脱氮技术,提出了燃煤锅炉深度脱硫脱氮需考虑多种技术相结合,并针对不同容量和燃烧方式的锅炉推荐了合适的深度脱硫脱氮技术,可为燃煤锅炉污染物排放达到新国标提供技术参考。 相似文献
430.
采用提出的“功能当量”相对评估模型,并以RS和GIS为技术平台对2009年天津滨海新区生态系统服务功能进行评估,采用区域网格化空间表达,对研究区进行分级研究.结果表明,滨海新区生态系统单位面积服务功能当量大小依次为湿地、水体、林地、草地、耕地、裸地;2009年滨海新区生态系统服务功能当量总和为1068680.13,III级以上功能当量的单元格比例为71.22%,总体处于较高水平;通过与价值量法结果对比,得出利用“功能当量”相对评估模型对研究区的评估结果与价值量法的评估结果具有显著相关性,证明该评估模型的可行性和合理性. 相似文献