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排序方式: 共有1311条查询结果,搜索用时 62 毫秒
71.
72.
Edward J. Phlips F J. Aidridge C. Hanlon 《Journal of the American Water Resources Association》1994,30(2):229-238
ABSTRACT: A 17-year record of chlorophyll a at eight limnetic sampling stations was used to evaluate putative changes in the trophic status of Lake Okeechobee, a shallow polymictic lake located in the subtropical environment of South Florida. Significant spatial differences were observed in the temporal patterns and variability of chlorophyll a concentrations. The highest chlorophyll a values were found in the northern and northwestern regions of the lake. The center of the lake, subject to high levels of non-algal suspended solids, exhibited relatively low chlorophyll a values and coefficient of variation. The lowest chlorophyll a values were observed at the southernmost sampling station in the lake. This was also the station that showed a significant upward trend in annual mean chlorophyll a values over the 17-year period of record. Examination of the relationship between chlorophyll a and three key environmental variables (i.e., total phosphorus concentration, phosphorus loading, and lake stage) revealed significant correlations at two out of the eight stations. The overall results of this study indicate that spatial and temporal disparities in the distribution and dynamics of chlorophyll a in Lake Okeechobee mandate more temporally and spatially intense approaches to the evaluation of trophic state than used in previous studies. 相似文献
73.
William W. Walker 《Journal of the American Water Resources Association》1995,31(4):671-685
ABSTRACT: The State of Florida (1994) has adopted a plan for addressing Everglades eutrophication problems by reducing anthropogenic phosphorus loads. The plan involves implementation of Best Management Practices in agricultural watersheds and construction of regional treatment marshes (Stormwater Treatment Areas or STA's). This paper describes the development, testing, and application of a mass-balance model for sizing STA's to achieve treatment objectives. The model is calibrated and tested against peat and water-column data collected in Water Conservation Area-2A (WCA-2A), where phosphorus dynamics and eutrophication impacts have been intensively studied. The 26-year-average rate of phosphorus accretion in peat is shown to be proportional to average water-column phosphorus concentration, with a proportionality constant of 10.2 m/yr (90 percent Confidence Interval = 8.9 to 11.6 m/yr). Spatial and temporal variations in marsh water-column data suggest that drought-induced recycling of phosphorus was important during periods of low stage in WCA-2A. Maintaining wet conditions will be important to promote phosphorus removal in STA's. Sensitivity analysis of STA performance is conducted over the range of uncertainty in model parameter estimates to assess the adequacy of the model as a basis for STA design. 相似文献
74.
Daniel E. Canfield 《Journal of the American Water Resources Association》1983,19(2):255-262
ABSTRACT: Models for the prediction of chlorophyll a concentrations were developed and tested using data on 223 Florida lakes. A statistical analysis showed that the best model was log (Chl a) =?2.49 + 0.269 log (TP) + 1.06 log (TN) or log (Chl a) =?2.49 + 1.06 log (TN/TP) + 1.33 log (TP) where Chl a is the chlorophyll a concentration (mg m-3), TP is the total phosphorus concentration (mg m-3) and TN is the total nitrogen concentration (mg m-3). The model yields unbiased estimates of chlorophyll a concentrations over a wide range of lake types and has a 95 percent confidence interval of 29–319 percent of the calculated chlorophyll a concentrations. Other models, especially the published Dillon-Rigler and Jones-Bachmann phosphorus-chlorophyll models, are less precise when applied to Florida lakes. The data support the hypothesis that nitrogen is an important limiting nutrient in hypereutrophic lakes. 相似文献
75.
Adnan Shindala 《Journal of the American Water Resources Association》1972,8(5):987-998
ABSTRACT. A comprehensive evaluation of current techniques for nutrients, nitrogen and phosphorus, removal from wastewaters was conducted by the author under a research project supported by the Office of Water Resources Research, Department of the Interior. The object of this study was to compile and evaluate, under one cover, the available information on current techniques for removing nutrients from wastewaters with emphasis on type of treatment (physical, chemical, biological, or any combination); economics (capital and operating costs); efficiencies, and applications. Due to space limitations, only a brief summary of this work is presented in this paper. A copy of the completion report may be obtained from the author. 相似文献
76.
本文介绍了关于洗涤剂中磷对环境影响的两种典型观点和解决的办法,并从经济和环境的角度进行全面的分析,得出合理的结论和建议。 相似文献
77.
78.
Jongeun You Jill Yordy Kyudong Park Tanya Heikkila Christopher M. Weible 《Journal of Environmental Policy & Planning》2020,22(4):501-517
ABSTRACT Researchers often focus on the most intense conflicts, skewing our perception of the diversity and nature of policy conflicts. The paper examines the discourse engaged in the siting of three pipeline projects under construction, each with varying levels of conflict, and one rejected project of high conflict. We analyze over 700 newspaper articles that span the life of each proposed pipeline and supplement the news media data with interviews. Using these data, we compare differences in actor types, frames, and behaviors in natural gas pipeline siting processes characterized by high, medium, and low conflict. Comparing the characteristics of energy siting conflicts at varying intensities helps support corresponding portrayals of how people engage in the policy process. This paper offers theoretical and empirical guidance on understanding policy conflict intensity variation. 相似文献
79.
80.
Ein Moosbiomonitoring zur Ermittlung atmosph?rischer Elementeintr?ge in die Euroregion Nei?e (D, PL, CZ) 总被引:1,自引:0,他引:1
Olaf Wappelhorst Siegfried Korhammer Uta -Susanne Leffler und Bernd Markert 《Umweltwissenschaften und Schadstoff-Forschung》2000,12(4):191-200
Zusammenfassung Durch ein Moosbiomonitoring sollte die H?he und die Verteilung der atmosph?rischen Deposition von 37 Elementen in der Euroregion
Nei?e (ERN) nach den politischen und wirtschaftlichen Ver?nderungen erfasst und mit anderen Regionen verglichen werden. Weiterhin
sollten die Akkumulationseigenschaften vonPleurozium schreberi undPolytrichum formosum, den in dieser Studie verwendeten Moosarten, miteinander verglichen werden.
Bis Anfang der 90er Jahre war diese Region Teil des “Schwarzen Dreiecks”, das sich durch eine extrem hohe atmosph?rische Staubbelastung
auszeichnete. Durch die Schlie?ung zahlreicher Betriebe, der Ausrüstung der Kraftwerke mit Filteranlagen, der abnehmenden
Bedeutung der Braunkohle als h?uslicher Energietr?ger ver?nderte sich die Situation drastisch.
Die Elementkonzentrationen in den Moosen der ERN lassen sich heute mit denen der alten Bundesl?nder vergleichen. Lediglich
für Fe und Ti konnten deutlich h?here Gehalte ermittelt werden. Dies ist auf den h?heren Anteil der Braunkohle als Energietr?ger
zurückzuführen. In der Region um Katowice in Oberschlesien konnten für einige Elemente mehr als 10 fach h?here Gehalte in
den Moosen als in der ERN ermittelt werden.
Das Oberschlesische Industrierevier weist eine derart hobe atmosph?rische Belastungen auf, dass hier ein dringender Handlungsbedarf
besteht.
Online-First: 21. Juni 2000 相似文献