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971.
Kenneth D. Schmidt 《Journal of the American Water Resources Association》1975,11(3):514-525
ABSTRACT: Sewage effluent is commonly disposed of on land in arid regions, and the majority usually recharges the groundwater. Few evaluations have been made of the effect of effluent disposal on groundwater quality in the west. Groundwater hydrologists are rarely involved with treatment plant design and operation or effluent disposal in the San Joaquin Valley, California. The author's purpose is to evaluate the effect of regional sewering programs on groundwater quality in this valley. Research was conducted on past studies of sewage effluent disposal. An extensive water sampling program was undertaken near the Fresno Sewage Treatment Plant. Chloride contents were used to trace recharged effluent. The extent of recharged effluent was delineated and traced for about ten miles. Sampling between the plant and the urban Fresno area indicated a high probability of large-scale leakage of raw sewage into the groundwater. 相似文献
972.
ABSTRACT: Climatic data such as temperature, solar radiation, relative humidity, and wind speed have been widely used to estimate evapotranspiration. Moat of the solar radiation data and portions of the relative humidity data are either not available or missing from the records in Puerto Rico. Depending upon the availability and data characteristics of records, three methods (including a regression technique, an averaging of historical data, and a regional average) were used to generate missing data, and a time series analysis was used to synthesize a series of climatic data. The limitations and applicability of each method are discussed. The results showed that the time series analysis method can be successfully used to synthesize a series of monthly solar radiations for several stations. The regression technique and the regional average can be successfully applied to generate missing monthly solar radiation data. The regression technique and the averaging of historical data have been satisfactorily used to interpolate missing monthly relative humidity. The explained variance (R2) varied from 0.68 to 0.88, which are both significant at the 0.05 level of significance. 相似文献
973.
ABSTRACT: A generalized skew map for Louisiana streams was developed using data from Louisiana, Mississippi, Arkansas, and Texas with 20 or more years of annual flood records. A comparison between the newly developed Louisiana Generalized Skew Map (LGSM) and the generalized skew map recommended by the U.S. Water Resources Council (WRCGSM) was performed. The mean square error for the LGSM was 16 percent less than that of WRCGSM in direct application of the two maps. Performance of the new map was compared with the WRCGSM and with a regional analysis procedure through its application to the Log Pearson Type 3 (LP3) distribution. Two-thirds of the stations tested had lower standardized root mean square deviations (SRMSD) by a narrow margin using the skew coefficients obtained from LGSM instead of WRCGSM. The regional analysis also performed as well as the LGSM in terms of SRMSD. Thus, it was concluded that both LGSM and the regional analysis provide a more reliable tool for flood frequency analysis for Louisiana streams with short annual flood records. 相似文献
974.
William Whipple 《Journal of the American Water Resources Association》1978,14(6):1449-1456
ABSTRACT: A few years ago, many water quality administrators were convinced that large regional sewerage systems, consisting of one large treatment plant and long trunk sewers extending out to various communities, represented the only efficient and economical means of assuring water quality control. In communities favoring rapid development, the provision of sewer service and encouragement of development of new centers along the trunk sewers offered an additional advantage. More recently quite different points of view are arising in certain areas. In parts of New Jersey strong environmental and community resistance has arisen to proposed central plant-trunk sewer systems. The facilitation of new development along the trunk sewers is viewed as a menace by townships not wanting intensive development of these areas. The diversion of effluent flows to trunk sewers rather than septic tanks would dry up the streams which water quality programs are supposed to protect. Both sides to the controversy have mobilized engineering, environmental, economic, and legal expertise and some critical policy issues have developed. Reconsideration of regional sewerage management and particularly trunk sewer policy is required. The decision as to extent of sewerage service areas involves complex and sensitive planning issues. Because of potential conflicts of interest, such decisions should not be left to staffs of sewerage authorities and their design engineers. 相似文献
975.
Endocrine disrupters in the aquatic environment 总被引:1,自引:0,他引:1
Petra Stahlschmidt-Allner Bernhard Allner Jörg Römbke Thomas Knacker 《Environmental science and pollution research international》1997,4(3):155-162
Possible mechanisms to explain endocrine effects on reproduction and sex differentiation are presented for selected pharmaceuticals,
agrochemicals, industrial chemicals and plant sterols which are known to be present in the aquatic environment. Disruptions
of the hormonal coordination can be induced by xenobiotics on various levels of the hierachically organised endocrine system
of vertebrates. Phthalate plasticisers, for example, may disrupt the pituitary control of gonadal functions; prenatal/larval
exposure to synthetic estrogen impairs sex differentiation and neuroendocrine sexual determination of the central nervous
system; phenylurea herbicides block the androgen receptor; the biotransformation of weakly estrogenic plant sterol components
of paper mill wastewater (e.g. βsitosterol) may lead to androgenic compounds. The effect of hypolipidemic drugs on lipid homeostasis
(peroxysom proliferation) is transmitted via a receptor protein that seems to be closely related to the endocrine system both
functionally as well as phylogenetically; possible interferences with the neuroendocrine control of sex differentiation are
also discussed. In invertebrates, tributyltin is known to effect the biosynthesis of steroidal sexual hormones. PCBs are suspected
to be competitive inhibitors of the steroid catabolism.
In order to identify potential risks caused by chemicals to the reproductive capacities of aquatic animals and to the quality
of drinking water, methods should be established to detect endocrine disrupters at the various levels of the endocrine system. 相似文献
976.
Coexisting animal species frequently differ in resource use in at least one niche dimension and thus avoid competition. While
a range of morphological differences that lead to differentiation in animals' mechanical access to food have been identified,
the role of sensory differences in within-guild niche differentiation has received less attention. We tested the hypothesis
that differences in sensory access to prey contribute to resource partitioning between potentially competing species using
two sympatric, similar-sized, congeneric bat species as a model system. Nursery colonies of Natterer's bat (Myotis nattereri) and Bechstein's bat (Myotis bechsteinii) roost in bat boxes in the same orchard and forage in forests and orchards nearby. In observations and behavioural experiments
with freshly captured M. bechsteinii, we showed that individuals are able to hunt using prey-generated sound alone. In contrast, M. nattereri rarely uses prey-generated sound, but instead is able to find prey by echolocation very close to vegetation. In accordance
with these behavioural data, we showed that M. bechsteinii has significantly larger ears than M. nattereri, providing it with superior detection and localization abilities for relatively low-frequency prey rustling sounds. We hypothesized
that these differences in sensory ecology of the two syntopic, congeneric species would contribute to resource partitioning,
so that M. bechsteinii would find more noisy prey taxa, possibly hidden in vegetation, by listening for prey sounds, while M. nattereri would have better access to still prey using echolocation or associative learning. Analysis of faecal samples collected on
the same nights from bat boxes occupied by each species corroborated this prediction. The diets of the two species differed
significantly, reflecting their different prey perception techniques and thereby supporting the hypothesis that differences
in sensory ecology contribute to niche differentiation.
Electronic supplementary material Supplementary material is available for this article at and accessible for authorised users.
B.M. Siemers and S.M. Swift contributed equally to this work. 相似文献
977.
Elevated particulate matter concentrations in urbanlocations have normally been associated with local trafficemissions. Recently it has been suggested that suchepisodes are influenced to a high degree by PM10sources external to urban areas. To further corroboratethis hypothesis, linear regression was sought betweenPM10 concentrations measured at eight urban sites inthe U.K., with particulate sulphate concentration measuredat two rural sites, for the years 1993–1997. Analysis ofthe slopes, intercepts and correlation coefficientsindicate a possible relationship between urban PM10and rural sulphate concentrations. The influences of winddirection and of the distance of the urban from the ruralsites on the values of the three statistical parametersare also explored. The value of linear regression as ananalysis tool in such cases is discussed and it is shownthat an analysis of the sign of the rate of change of theurban PM10 and rural sulphate concentrations providesa more realistic method of correlation. The resultsindicate a major influence on urban PM10 concentrations from the eastern side of the UnitedKingdom. Linear correlation was also sought using PM10 data from nine urban sites in London and nearby ruralRochester. Analysis of the magnitude of the gradients andintercepts together with episode correlation analysisbetween the two sites showed the effect of transportedPM10 on the local London concentrations. This articlealso presents methods to estimate the influence of ruraland urban PM10 sources on urban PM10 concentrations and to obtain a rough estimate of thetransboundary contribution to urban air pollution from thePM10 concentration data of the urban site. 相似文献
978.
In 1990, the National Research Council (NRC) published two in-depth assessments of marine environmental monitoring effectiveness. The first of these, Managing Troubled Waters: The Role of Marine Environmental Monitoring, provided a national perspective and the second, Monitoring Southern California's Coastal Waters, examined the specifics of monitoring design and implementation in a densely populated, highly urbanized coastal region. The reports include explicit recommendations about the need for greater regionalization of monitoring efforts, supported by greater standardization of field, laboratory, and data analysis methods. They also identified the need for centralized data management and for greater flexibility in the language of standard discharge permits, flexibility that would permit discharge agencies to more readily participate in regional monitoring and research programs. Other recommendations identified a need for EPA and NOAA to focus on creating a national monitoring program structured as a network of coordinated local and regional efforts. Finally, the NRC emphasized the need for better reporting and for periodic review of monitoring's relevance to management concerns. In this paper, we use southern California as a test case to assess progress made in implementing the NRC's recommendations. We review progress made on each recommendation and discuss the features of the regulatory and management climate that contributed to or impeded this progress. We also consider whether, and to what extent, the NRC's recommendations remain relevant in the present context. 相似文献
979.
Viglizzo EF Pordomingo AJ Castro MG Lertora FA 《Environmental monitoring and assessment》2003,87(2):169-195
Governments need good information to design policies. However, inthe Argentine Pampas there are neither sufficient knowledge on environmental issues, nor clear perception of environmental alterations across space and time. The general objective of this work was to provide decision makers with a scientifically sound set of indicators aiming at the assessment of current status andfuture trends in the rural environment of this sensitiveregion. As driving criteria to select indicators, weassumed that they had to be sound, simple to calculate,easy to understand, and easily applicable by decision makers. They are related closely to significantecological structures and functions. Twelve basicindicators were identified: (1) land use, (2) fossil energyuse, (3) fossil energy use efficiency, (4) nitrogen (N)balance, (5) phosphorus (P) balance, (6) nitrogencontamination risk, (7) phosphorus contamination risk, (8) pesticide contamination, (9) soil erosion risk, (10) habitatintervention, (11) changes in soil carbon stock, and (12) balance of greenhouse gases. Indicators were geographicallyreferenced using a geographic information system (GIS). Thestrength of this study is not in the absolute value ofenvironmental indicators, but rather in theconceptualization of indicator and the identification ofchanging patterns, gradients and trends in space and time.According to our results, we can not definitely say thatagriculture in the Pampas, as a whole, tends to besustainable or not. While some indicators tend to improve,others keep stable, and the rest worsen. The relative importance among indicators must also be considered. The indicators that showed a negative net change are key to the identification of critical problems that will require special attention in the close future. 相似文献
980.
Using Temporal Coherence to Determine the Response to Climate Change in Boreal Shield Lakes 总被引:1,自引:0,他引:1
Arnott SE Keller B Dillon PJ Yan N Paterson M Findlay D 《Environmental monitoring and assessment》2003,88(1-3):365-388
Climate change is expected to have important impacts on aquatic ecosystems. On the Boreal Shield, mean annual air temperatures are expected to increase 2 to 4°C over the next 50 years. An important challenge is to predict how changes in climate and climate variability will impact natural systems so that sustainable management policies can be implemented. To predict responses to complex ecosystem changes associated with climate change, we used long-term biotic databases to evaluate how important elements of the biota in Boreal Shield lakes have responded to past fluctuations in climate. Our long-term records span a two decade period where there have been unusually cold years and unusually warm years. We used coherence analyses to test for regionally operating controls on climate, water temperature, pH, and plankton richness and abundance in three regions across Ontario: the Experimental Lakes Area, Sudbury, and Dorset. Inter-annual variation in air temperature was similar among regions, but there was a weak relationship among regions for precipitation. While air temperature was closely related to lake surface temperatures in each of the regions, there were weak relationships between lake surface temperature and richness or abundance of the plankton. However, inter-annual changes in lake chemistry (i.e., pH) were correlated with some biotic variables. In some lakes in Sudbury and Dorset, pH was dependent on extreme events. For example, El Nino related droughts resulted in acidification pulses in some lakes that influenced phytoplankton and zooplankton richness. These results suggest that there can be strong heterogeneity in lake ecosystem responses within and across regions. 相似文献