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81.
Importance of Sediment–Water Interactions in Coeur d’Alene Lake,Idaho, USA: Management Implications 总被引:1,自引:0,他引:1
Kuwabara JS Carter JL Topping BR Fend SV Woods PF Berelson WM Balistrieri LS 《Environmental management》2003,32(3):348-359
A field study at Coeur dAlene Lake, Idaho, USA, was conducted between October 1998 and August 2001 to examine the potential importance of sediment–water interactions on contaminant transport and to provide the first direct measurements of the benthic flux of dissolved solutes of environmental concern in this lake. Because of potential ecological effects, dissolved zinc and orthophosphate were the solutes of primary interest. Results from deployments of an in situ flux chamber indicated that benthic fluxes of dissolved Zn and orthophosphate were comparable in magnitude to riverine inputs. Tracer analyses and benthic-community metrics provided evidence that solute benthic flux were diffusion-controlled at the flux-chamber deployment sites. That is, effects of biomixing (or bioturbation) and ground-water interactions did not strongly influence benthic flux. Remediation efforts in the river might not produce desired water-quality effects in the lake because imposed shifts in concentration gradients near the sediment–water interface would generate a benthic feedback response. Therefore, development of water-quality models to justify remediation strategies requires consideration of contaminant flux between the water column and underlying sediment in basins that have been affected by long-term (decadal) anthropogenic activities. 相似文献
82.
83.
Johan Bergholm Hooshang Majdi Tryggve Persson 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):225-234
A nitrogen (N) budget was constructed for a period of 6 years (1988–1993) in a Norway spruce stand with current deposition
of 19 kg N and 22 kg S ha−1 year−1. The stand was fertilized annually by addition of 100 kg N and 114 kg S ha−1 (NS). Above and below ground biomass, litterfall, fine- root litter production, soil solution and net mineralization were
measured to estimate pools, fluxes and accumulation of nitrogen. The average needle litterfall in control (C) and NS plots
in 1993 was 2.2 and 2.5 ton ha−1 year−1, respectively. The fine root litter production prior to treatment (1987) was 4.4 ton ha−1 year−1 and after treatment (1993) it was 4.5 and 3.9 ton ha−1 year−1 in C and NS plots, respectively. Net N mineralization in the soil profile down to 50 cm was estimated to be 86 and 115 kg
ha−1 year−1 in C and NS plots, respectively in 1992. During the treatment period the uptake of N in the needle biomass in C and NS plots
was 29 and 77 kg ha−1 year−1, respectively. No N was accumulated in needles of C plot where the NS plots accumulated 34 kg ha−1 year−1. Of the annually added inorganic N to NS plots 47% was accumulated in the above and below ground biomass and 37% in the soil.
N fluxes via fine-root litter production in the C plots were much higher (54 kg ha−1 year−1) than that via litterfall (29 kg ha−1 year−1). The corresponding values in the NS plots were 65 and 43 kg ha−1 year−1, respectively. Most of the net N mineralization occurred in the FH layer and upper mineral soil. It is concluded that fine
root litter and litterfall play an important role in the cycling of N. Despite a high N uptake the losses of N in litterfall
and fine root litter resulted in an incorporation of N in soil organic matter. 相似文献
84.
85.
根据扩容机理,建立了扩容爆破的物理模型,并且根据动量守恒定律得到了不同条件下最终炮孔挤压区域的半径公式.利用这些公式结合炸药和岩石的特性,以及装药参数得到了扩容结果.理论计算结果与试验数据相吻合.这些结果将有助于爆破扩容理论的完善以及该技术发展和推广应用. 相似文献
86.
87.
ABSTRACT: Following an enclosure of a sink-hole connecting Lake Tarpon to the Gulf of Mexico, the chloride concentration of lake waters decreased. Water and chloride budgets for the lake in 1975 were prepared, and predictions using the model of Lerman and Brunskill (1971) were made as to the time required for the lake to achieve fresh water status. Model verification indicated good agreement with predictions in 1976; however, data on [C1-] for 1977 and 1978 are not as supportive of the model used. The information concerning the Lake Tarpon watershed provided by this latter fact is discussed. 相似文献
88.
Michael N. Beaulac Kenneth H. Reckhow 《Journal of the American Water Resources Association》1982,18(6):1013-1024
ABSTRACT: Lake and watershed management strategies and recent environmental legislation dictate that nonpoht nutrient sources associated with storm water runoff must be assessed. Accordingly, a nutrient flu assessment for phosphorus and nitrogen is conducted through an extensive literature review of nutrient export studies. These studies are reevaluated. The nutrient export coefficients are screened according to sampling design criteria and compiled according to land use. The ecological mechanisms within each land use influencing the magnitude of nutrient flux are also discussed 相似文献
89.
采用芳香聚酰胺膜(NF-1#)、复合膜(NF-2#)和聚酰胺复合膜(NF-3#)深度处理棉针织品印染废水,考察了膜分离性能及膜污染情况的影响因素。实验结果表明,在操作压力为0.5MPa、废水温度为25~35℃、废水pH为7的条件下,NF-1#膜处理效果最佳,COD去除率最高,为76.0%~85.0%;脱盐率也最高,达90.0%。膜过滤后浓水送污水厂处理,产水回用于车间生产。操作压力增高、废水温度升高和废水pH增大均导致滤饼层阻力(Rc)和膜过滤过程中的总阻力(Rt)增加,Rc是Rt的主要组成部分,同时也是导致膜透过通量下降的主要因素。 相似文献
90.
Gerosa G Marzuoli R Desotgiu R Bussotti F Ballarin-Denti A 《Environmental pollution (Barking, Essex : 1987)》2008,152(2):274-284
An Open-Top Chambers experiment on Fagus sylvatica and Quercus robur seedlings was conducted in order to compare the performance of an exposure-based (AOT40) and a flux-based approaches in predicting the appearance of ozone visible injuries on leaves. Three different ozone treatments (charcoal-filtered; non-filtered; and open plots) and two soil moisture treatments (watered and non-watered plots) were performed. A Jarvisian stomatal conductance model was drawn up and parameterised for both species and typical South Alpine environmental conditions, thus allowing the calculation of ozone stomatal fluxes for every treatment. A critical ozone flux level for the onset of leaf visible injury in beech was clearly identified between 32.6 and 33.6 mmolO3 m(-2). In contrast, it was not possible to identify an exposure critical level using the AOT40 index. Water stress delayed the onset of the leaf visible injuries, but the flux-based approach was able to take it into account accurately. 相似文献