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931.
Anthony B. Muller 《Journal of the American Water Resources Association》1974,10(2):245-255
ABSTRACT: A groundwater quality change of +0.13 millimhos electrical conductivity was documented between 1940 and 1 972 in the Safford Valley. The change is attributable to four principal mechanisms: pumping-encouraged saline artesian aquifer leakage, natural recharge of the water table aquifer by saline waters, leaching of agricultural waters into the aquifer and the lateral flow of groundwater through saline lacustrine beds. A hydrologic study of the area has shown the first of these mechanisms to be predominant. Salinity modeling has shown three regions of salinity change, and salinity increase projections for each are determined. An economic analysis and an economic model are then combined with the physical model, yielding information as to when certain economic conditions are reached with respect to the salinity increase. This combined model shows that, based on projected salinity trends, cotton, the principal agricultural crop of the valley, will remain economical to cultivate for a significant time beyond the model's limit of prediction. Alfalfa, on the other hand, should go out of production in large areas of the valley by 1990, and not be under economical cultivation by 2040. A sociologic model, based on the cluster analysis of questionnaire data, shows an awareness of the salinity problems of the area but little concern over them. Interdisciplinary model based salinity control regulations are made. 相似文献
932.
Robert L. Wilbur 《Journal of the American Water Resources Association》1974,10(2):372-383
ABSTRACT: Conversion of muck to sand bottom was tested to increase benthic production in two eutrophic Florida lakes, and preliminary results indicate that benthos will be increased in areas converted to sand. Muck removal with a specially designed dredge, or “Mudcat,” was tested in Trout Lake. The Mudcat removed 41,650 cu. yds. of muck and exposed 17 acres of sand bottom, but 10 of those acres developed thin layers of muck, which proved too soft to be picked up by the Mudcat. Consequently, only 7 acres were satisfactorily converted. Bottom redistribution with a suction-type dredge was tested in Lake Carlton, and 14 acres were converted from muck to sand. Sand covered with muck was pumped from midlake areas to more peripheral areas of the lake where water depths were 11 to 13 feet and muck layer about 1.5 feet deep. The bottom was built up to an elevation above the previous muck elevation. Several methods for depositing the sand were tested. Level areas of sand fill developed accumulations of muck from fallout following dredging activity. Piles or dunes provided the best cost-return ratio. The bottom in filled areas changed very little during a 1½ year period following filling. 相似文献
933.
Edwin T. Engmun 《Journal of the American Water Resources Association》1974,10(3):512-521
ABSTRACT: According to a concept known as partial area hydrology, watershed areas are separated into hydrologically active and passive subareas. The literature relating to the development of the partial area concept is reviewed briefly and the relationship of partial area hydrology to geology, soils, and micrometeorology is illustrated. The potential application of partial area hydrology is discussed with respect to present hydrologic techniques, future hydrologic models, urban hydrology, water quality, and water management. Suggestions for identifying and delineating the contributing areas are discussed. 相似文献
934.
本文对乌鲁木齐市大气环境质量及其发展趋势作了简要的分析,说明目前市大气属煤烟-沙尘型污染区,氮氧化物和二氧化硫随着国民经济能耗的增加有发展的趋势,其它污染物仍稳定在目前水平,或稍有下降. 相似文献
935.
936.
应用多目标决策中的TOPSIS法(即逼近于理想解的排序方法)对湖南长沙等十城市的大气环境质量进行评价,并与欧几里德贴近度法和上海指数法相比较,认为该评价方法对比较多个城市(或多个监测点,下同)的大气环境质量的优劣,比欧几里德贴近度法和上海指数法均优越. 相似文献
937.
Mahrous M. Kandil Ahmed F. El-Aswad William C. Koskinen 《Journal of environmental science and health. Part. B》2013,48(7):473-483
Sorption–desorption of the insecticide imidacloprid 1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine onto a lacustrine sandy clay loam Egyptian soil and its clay and humic acid (HA) fractions was investigated in 24-h batch equilibrium experiments. Imidacloprid (IMDA) sorption–desorption isotherms onto the three sorbents were found to belong to a non-linear L-type and were best described by the Freundlich model. The value of the IMDA adsorption distribution coefficient, Kdads, varied according to its initial concentration and was ranged 40–84 for HA, 14–58 for clay and 1.85–4.15 for bulk soil. Freundlich sorption coefficient, Kfads, values were 63.0, 39.7 and 4.0 for HA, clay and bulk soil, respectively. The normalized soil Koc value for imidacloprid sorption was ~800 indicating its slight mobility in soils. Nonlinear sorption isotherms were indicated by 1/nads values <1 for all sorbents. Values of the hysteresis index (H) were <1, indicating the irreversibility of imidacloprid sorption process with all tested sorbents. Gibbs free energy (ΔG) values indicated a spontaneous and physicosorption process for IMDA and a more favorable sorption to HA than clay and soil. In conclusion, although the humic acid fraction showed the highest capacity and affinity for imidacloprid sorption, the clay fraction contributed to approximately 95% of soil-sorbed insecticide. Clay and humic acid fractions were found to be the major two factors controlling IMDA sorption in soils. The slight mobility of IMDA in soils and the hysteresis phenomenon associated with the irreversibility of its sorption onto, mainly, clay and organic matter of soils make its leachability unlikely to occur. 相似文献
938.
W. K. KIM R. C. ANDERSON A. L. RATLIFF D. J. NISBET S. C. RICKE 《Journal of environmental science and health. Part. B》2013,48(1):97-107
The overall objective of this study was to evaluate the potential ability of nitrocompounds to reduce ammonia volatilization by inhibiting uric acid–utilizing microorganisms. Experiment I was conducted to evaluate the effects of nitrocompounds on the growth of uric acid–utilizing microorganisms isolated from poultry manure during six-hour incubation. There were five treatments: (1) control, (2) 50 mM nitroethane, (3) 50 mM nitroethanol, (4) 50 mM nitropropanol, and (5) 50 mM nitropropionic acid. Optical density values of nitrocompounds were significantly lower than that of control at two, four, and six hours. Plate counts of uric acid–utilizing microorganisms after six-hour incubation exhibited that nitrocompounds greatly reduced the growth of these microorganisms except for the nitroethane (P < 0.05). The nitropropanol and nitropropionic acid treatments showed significantly higher inhibitory effects compared to the nitroethanol. Experiments II and III were conducted to evaluate inhibitory effects of nitrocompounds on growth of uric acid–utilizing microorganisms compared to non-nitrocompounds such as ethanol, propanol, and propionic acid. Experiments II and III consisted of seven treatments: (1) control, (2) nitroethanol, (3) nitropropanol, (4) nitropropionic acid, (5) ethanol, (6) propanol, and (7) propionic acid. The incubation times of Experiments II and III were 6 and 24 h, respectively. The nitrocompounds were significantly more successful in inhibiting growth of uric acid–utilizing microorganisms compared to those non-nitrocompounds. These results suggest that nitrocompounds exhibit potential to reduce ammonia volatilization in poultry manure by inhibiting growth of uric acid–utilizing microorganisms. 相似文献
939.
Nicoleta A. Suciu Ettore Capri 《Journal of environmental science and health. Part. B》2013,48(6):525-532
Sorption of three pesticides (chlorpyrifos, metalaxyl and penconazole) has been measured on a commercial clay montmorillonite and on the same mineral modified with either of two cationic-surfactant micelles. Both micelle–clay complexes, commercial names Cloisite 20A and Cloisite 30B, showed a good capacity to sorb all three pesticides from water, whereas their sorption on the natural montmorillonite was not described by an isotherm. Modelling sorption on both micelle–clay complexes showed that the Freundlich sorption constant (K F) was higher for chlorpyrifos on Cloisite 20A (K F = 7.76) than on Cloisite 30B (K F = 5.91), whereas the sorption of metalaxyl was stronger on Cloisite 30B (K F = 1.07) than on Cloisite 20A (K F = 0.57). Moreover the micelle–clay complex Cloisite 20A also showed a good affinity for penconazole, the maximum quantity adsorbed (q m) of 6.33 mg g?1 being 45% more than that on Cloisite 30B. Single-batch adsorption of each pesticide onto both micelle–clay complexes was studied using the Freundlich isotherm for chlorpyrifos and metalaxyl and the Langmuir isotherm for penconazole. The Cloisite 20A micelle–clay complex was predicted to require 23% less adsorbent to treat certain volumes of wastewater containing 30 mg L?1 chlorpyrifos, 43% more to treat metalaxyl similarly and 57% less to treat penconazole compared with Cloisite 30B. 相似文献
940.
王云 《中国环境管理干部学院学报》2012,22(2):68-72
研究了短时游离氯后转氯胺的联合消毒方法对大肠杆菌的灭活作用,并对其协同作用以及pH值和温度对协同作用的影响进行了探讨。结果表明:pH值在6.5~8范围内,温度不超过30℃时,短时游离氯后转氯胺的消毒方法对大肠杆菌的灭活具有协同作用,且随pH值的降低而加强,在低温下该方法的协同效果更加明显。 相似文献