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排序方式: 共有190条查询结果,搜索用时 453 毫秒
141.
Warren Viessman 《Journal of the American Water Resources Association》1990,26(6):883-891
ABSTRACT: This paper summarizes contemporary water management issues as recognized by 19 U.S. organizations. Only the issues are identified herein. Individual organization stands are not presented. Most suggestions for action are those of the author. Addresses of all organizations whose documents were reviewed are included in the Reference section so that those desiring to learn more about an organization's stand can readily make contact. 相似文献
142.
N Behmanesh D T Allen J L Warren 《Journal of the Air & Waste Management Association》1992,42(4):437-442
The quantity and composition of RCRA hazardous wastes incinerated during 1986 were examined using the National Hazardous Waste Survey. This Survey, collected for U.S. EPA by the Research Triangle Institute, is the most extensive examination of hazardous waste generation and management available. The survey data show that although a wide variety of hazardous wastes were treated by incineration, more than 75 percent of incinerated waste streams were from chemical manufacturing. The survey data also show that more than 90 percent of the incinerated wastes were treated by incinerators located at the facility generating the waste. Despite the predominance of a single industrial sector in generating incinerated hazardous wastes, the compositional profile of the wastes is far from uniform. To illustrate this variability, the metals and chlorine content of the wastes are reported along with the sources of the metal and chlorine loadings. 相似文献
143.
The Great Lakes may be viewed as a coastal environment, affected by the same meteorological and physical forces as the coastal ocean. The U.S. EPA, Great Lakes National Program Office (GLNPO) has monitored the open waters of the lakes, annually, since 1983. As part of the U.S. EPA Environmental Monitoring and Assessment Program (EMAP), a pilot study was performed in Lake Michigan to compare the existing GLNPO deterministic sampling grid with the EMAP probabilistic grid. Results of chemical analyses of trophic status indicators (total phosphorus and chlorophyll a) as well as nutrients and conventional limnological measurements, from spring and summer surveys in 1992 indicate little difference between the grids in the offshore region of the lake. The few statistically significant differences may be due to station distribution throughout the lake, or simple chance. This might be expected due to the well mixed nature of the open waters of Lake Michigan. The detection of a long-term trend for total phosphorus in Lake Michigan benefits from an annual program: viewing cumulative frequency distributions based on a four year EMAP interval does not convey information on the decrease in phosphorus in the lake. If the EMAP sampling grid were to be used in the Great Lakes, pilots in each of the lakes would be necessary for utilization of the existing long-term record as a basis for trend detection. 相似文献
144.
Warren Viessman Karen E. Stork 《Journal of the American Water Resources Association》1973,9(4):647-654
In recent years, important changes have occurred in water resources research. There have been major shifts in attitudes of Congress, state legislatures and the general public toward water and related resource issues. Future water research and development will have to be environmentally oriented. Emphasis is shifting to research productivity. To justify research expenditures, hard facts must be produced which demonstrate payoff. Technology transfer (getting research results into the hands of users in an understandable and usable form) is gaining prominence. Research projects must be designed for total problem solution and technology transfer must be incorporated as a part of project objectives. Research must be planned and conducted to meet users' needs. Guidelines for modern research design and technology transfer are presented. 相似文献
145.
T.A. Marsagishvili S.A. Kirillov V.A. Chagelishvili N.SH. Ananiashvili D.I. Dzanashvili T. V. Lesnichaya 《Chemistry and Ecology》2013,29(1):87-91
Samples with the best adsorption properties are selected as a result of investigations conducted on synthesis of manganese-dioxide-based materials and study of their physicochemical properties. Materials were selected on the basis of their low cost and the simplicity of their production technology. In the laboratory the synthesis and analyses of materials was carried out for selected samples. The sorption of a series of elements is studied for a more detailed investigation of materials obtained. The results obtained will promote the synthesis of materials with improved adsorption properties with the aim of their application for purification of water from strontium. It is shown that the most promising way for amendment of manganese oxide is modification of this material using acid-resistant oxides. These oxides are also less expensive than existing sorbents for strontium. 相似文献
146.
I. J. Staniland N. Gales N. L. Warren S. L. Robinson S. D. Goldsworthy R. M. Casper 《Marine Biology》2010,157(11):2383-2396
Foragers show adaptive responses to changes within their environment, and such behavioural plasticity can be a significant
driving force in speciation. We investigated how lactating Antarctic fur seals, Arctocephalus gazella, adapt their foraging within two contrasting ecosystems. Location and diving data were collected concurrently, between December
2003 and February 2004, from 43 seals at Bird Island, where krill, Euphausia superba, are the main prey, and 39 at Heard Island, where mostly fish are consumed. Seals at Heard Island were shorter and lighter
than those at Bird Island and they spent longer at sea, dived more frequently and spent more time in the bottom phase of dives.
Generalized additive mixed effects models showed that diving behaviours differed between the islands. Both populations exploited
diel vertically migrating prey species but, on average, Heard Island seals dived deeper and exceeded their estimated aerobic
dive limits. We propose that the recovery of the Heard Island population may be limited by the relative inaccessibility and
scarcity of food, whereas at Bird Island, the presence of abundant krill resources helps sustain extremely high numbers of
seals, even with increased intra- and inter-specific competition. Both populations of fur seals appear to be constrained by
their physiological limits, in terms of their optimal diving behaviour. However, there does appear to be some flexibility
in strategy at the level of trip with animals adjusting their time at sea and foraging effort, in order to maximize the rate
of delivery of energy to their pups. 相似文献
147.
Guangjian Xu Xiaoxiao Zhong Yangfan Wang Alan Warren Henglong Xu 《Environmental science and pollution research international》2014,21(23):13461-13469
The functional parameters, i.e., the estimated equilibrium species number (S eq ), the colonization rate constant, and the time taken to reach 90 % of S eq (T 90 ), of microperiphyton fauna have been widely used to determine the water quality status in aquatic ecosystems. The objective of this investigation was to develop a protocol for determining functional parameters of microperiphyton fauna in colonization surveys for marine bioassessment based on rarefaction and regression analyses. The temporal dynamics in species richness of microperiphyton fauna during the colonization period was analyzed based on a dataset of periphytic ciliates in Chinese coastal waters of the Yellow Sea. The results showed that (1) based on observed species richness and estimated maximum species numbers, a total of 16 glass slides were required in order to achieve coefficients of variation of <5 % in the functional parameters; (2) the rarefied average species richness and functional parameters showed weak sensitivity to sampling effort; (3) the temporal variations in average species richness were well-fitted to the MacArthur-Wilson model; and (4) the sampling effort of ~8 glass slides was sufficient to achieve coefficients of variation of <5 % in equilibrium average species number (AvS eq ), colonization rate (AvG), and the time to reach 90 % of AvS eq (AvT 90 ) based on the average species richness. The findings suggest that the AvS eq , AvG, and AvT 90 values based on rarefied average species richness of microperiphyton might be used as reliable ecological indicators for the bioassessment of marine water quality in coastal habitats. 相似文献
148.
Recycling Irrigation Reservoir Stratification and Implications for Crop Health and Production
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Haibo Zhang Patricia A. Richardson Bruk E. Belayneh Andrew Ristvey John Lea‐Cox Warren E. Copes Gary W. Moorman Chuanxue Hong 《Journal of the American Water Resources Association》2016,52(3):620-631
Recycling irrigation reservoirs (RIRs) are an emerging aquatic ecosystem and water resource of global significance. This study investigated the vertical distribution of water temperature, dissolved oxygen (DO), and pH in eight RIRs at two nurseries each in Virginia and Maryland from 2011 to 2014. Monomictic thermal stratification was observed from April to October in all RIRs, despite their shallow depths (0.75‐3.89 m). The strongest stratification had a top‐bottom temperature difference of 21.53°C. The top‐bottom temperature difference was positively correlated with water column depth, air temperature, and daily light integral (p < 0.05). Wind speed did not impact the thermal stratification, likely due to their relatively small surface areas. Thermal stratification affected the vertical distribution of DO and pH. The top‐bottom differences in DO and pH were greater during stratification periods than nonstratification periods. Water pH in all RIRs was higher at the top than at the bottom with the greatest difference of 4.16 units. Discovery and characterization of thermal stratification in RIRs helps understand water quality dynamics in this novel ecosystem and promote safe and productive water reuse for irrigation. Specifically, water withdrawal depths should be adjusted according to variations in temperature, DO, and pH during the stratification and nonstratification periods to mitigate pathogen risk and improve water treatment efficacy and crop production. 相似文献
149.
Phosphorus (P) losses to surface waters can result in eutrophication. Some industrial by-products have a strong affinity for dissolved P and may be useful in reducing nonpoint P pollution with landscape-scale runoff filters. Although appreciable research has been conducted on characterizing P sorption by industrial by-products via batch isotherms, less data are available on P sorption by these materials in a flow-through context integral to a landscape P filter. The objectives of this study were to evaluate several industrial by-products for P sorption in a flow-through setting, to determine material chemical properties that have the greatest impact on P sorption in a flow-through setting, and to explore how retention time (RT) and P concentration affect P removal. Twelve materials were characterized for chemical properties that typically influence P removal and subjected to flow-through P sorption experiments in which five different RTs and P concentrations were tested. The impact of RT and P concentrations on P removal varied based on material chemical properties, mainly as a function of oxalate-extractable aluminum (Al), iron (Fe), and water-soluble (WS) calcium (Ca). Statistical analysis showed that materials elevated in oxalate-extractable Al and Fe and WS Ca and that were highly buffered above pH 6 were able to remove the most P under flow-through conditions. Langmuir sorption maximum values from batch isotherms were poorly correlated with and overestimated P removal found under flow-through conditions. Within the conditions tested in this study, increases in RT and inflow P concentrations increased P removal among materials most likely to remove P via precipitation, whereas RT had little effect on materials likely to remove P via ligand exchange. 相似文献
150.