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41.
Rates of alder leaf decomposition were used as an ecosystem-level measure of effects of untreated and treated acid mine drainage on two Colorado mountain streams. Untreated mine effluents had low pH and high concentrations of metals, particularly iron. Deposition of ferric hydroxide on leaf surfaces inhibited colonization by decomposers, such as fungi and aquatic insects, and thus little leaf breakdown occurred. Treated effluents had improved water quality (basic pH, low metal concentrations), but suspended flocs released by the treatment process buried leaves and reduced consumer activity. The rate of leaf breakdown was not significantly different from the rate with untreated effluents; thus improvement in water quality alone was insufficient to restore this important pathway of energy flow in headwater streams. 相似文献
42.
The investigation concerns the impact of the new school environment on a group of 50 male and female children aged 11–16 years, who leave home to reside temporarily at boarding school, in terms of the characteristics of problems and worries reported and the incidence of spontaneous reports of homesickness. More problems relating to the school than to the home environment were reported but proportionally more worry units were reported associated with home problems for both males and females. There was no sex differences in this respect. The reported level of spontaneously reported homesickness was 16% and there were no sex differences. Factors such as age, geographical distance of move and decision to go away to school were not influential in determining the level of reported problems or incidence of spontaneous reports of homesickness. A relationship was found with level of problems reported and recent life history but the result proved difficult to interpret. 相似文献
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Murray R. McComas G. Dennis Cooke Robert H. Kennedy 《Journal of the American Water Resources Association》1976,12(3):519-528
ABSTRACT A record snowfall of 55.8 centimeters occurred on December 1 and 2, 1974 in Portage County, Ohio. An early winter thaw melted the greater part of the snow by December 22, 1974, and a two-day rain fell from December 23 to December 25. These weather events provided an opportunity to compare snowmelt and rainfall contribution to runoff and phosphorus loading to the Twin Lakes Watershed. Phosphorus concentrations of the snow and rain were determined. Six lake inflows and two lake outflows were measured daily for volume and phosphorus concentration. The snow added 217,000 cubic meters of water and 2.2 kilograms of total phosphorus to the watershed. The rain added 74,000 cubic meters of water and 1.6 kilograms of total phosphorus. Total water discharge from the watershed during December was 244,537 cubic meters and total phosphorus output was 20.3 kilograms. The snow provided 49.9% of the discharge and 8% of the phosphorus whereas the rainfall contributed 28% of the discharge and 6% of the phosphorus. These results indicate that while snow is a significant source of water, it is not a large source of phosphorus. The greatest contribution of phosphorus comes from fine sediment carried by storm runoff. 相似文献
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Field evaluation of in situ remediation of a heavy metal contaminated soil using lime and red-mud 总被引:18,自引:0,他引:18
Gray CW Dunham SJ Dennis PG Zhao FJ McGrath SP 《Environmental pollution (Barking, Essex : 1987)》2006,142(3):530-539
We evaluated the effectiveness of lime and red mud (by-product of aluminium manufacturing) to reduce metal availability to Festuca rubra and to allow re-vegetation on a highly contaminated brown-field site. Application of both lime and red mud (at 3 or 5%) increased soil pH and decreased metal availability. Festuca rubra failed to establish in the control plots, but grew to a near complete vegetative cover on the amended plots. The most effective treatment in decreasing grass metal concentrations in the first year was 5% red mud, but by year two all amendments were equally effective. In an additional pot experiment, P application in combination with red mud or lime decreased the Pb concentration, but not total uptake of Pb in Festuca rubra compared to red mud alone. The results show that both red mud and lime can be used to remediate a heavily contaminated acid soil to allow re-vegetation. 相似文献
49.
Cadle SH Belian TC Black KN Carlock MA Graze RR Minassian F Murray HB Nam EK Natarajan M Lawson DR 《Journal of the Air & Waste Management Association (1995)》2006,56(2):121-136
The Coordinating Research Council held its 15th workshop in April 2005, with nearly 90 presentations describing the most recent mobile source-related emissions research. In this paper, the authors summarize the presentations from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles (with an emphasis in this workshop on particle emissions), effects of fuels on emissions, evaluation of in-use emissions control programs, and efforts to improve our capabilities in performing on-board emissions measurements, as well as topics for future research. 相似文献
50.
Cephalopod prey of the grey-headed albatrossDiomedea chrysostoma 总被引:3,自引:0,他引:3
Cephalopod remains were collected, at regular intervals throughout the fledging period, from the stomach contents of chicks of the grey-headed albatrossDiomedea chrysostoma at Bird Island, South Georgia, in 1984 and 1986 and from regurgitations of adults at the nest in 1986. The 1984 sample was taken during a season characterised by abnormal local oceanographic conditions in which the breeding success was very low; in 1986 conditions were normal and breeding success was high. Cephalopod beaks (289 from adults; 5 651 from chicks) were identified, and allometric equations were used to estimate the biomass represented. Five cephalopod species belonging to five families (Gonatidae, Onychoteuthidae, Psychroteuthidae, Ommastrephidae and Cranchiidae) contributed 98% by number and 97% of the biomass fed to chicks. The most important species was the ommastrephidMartialia hyadesi, contributing 68.9 to 77.4% by number and 72.5 to 79.3% of the total biomass fed to chicks. The relative proportions of cephalopod species in the chicks' diet were similar between 1984 and 1986, but the total number and biomass was significantly less in 1984. There is evidence of growth ofM. hyadesi between January and June. 相似文献