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161.
太湖铜锈环棱螺对氮磷的降解作用 总被引:18,自引:0,他引:18
太湖的五湖里湾是一个富营养湖,水质亟待改善。铜锈环棱螺是太湖的常见种群,通过在五里湖的一些室内外实验,研究了螺对水体透明度,总磷、氨氮、溶解氧的作用,发现它能交水体透明度从0.5m左右提高到1.3m,使室内水体浊度迅速降低,降解总磷的幅度能达到50%,分析为铜锈环棱螺的絮凝作用所致;并且,在其水域氨氮深度大幅度降低,使实验点高达5mg/L以上的氨氮浓度降至2mg/L以下,从感观和水质指标两方面有效 相似文献
162.
R. Edward Beighley Thomas Dunne John M. Melack 《Journal of the American Water Resources Association》2008,44(1):62-74
Abstract: The transport of water, sediment, dissolved and particulate chemicals, and bacteria from coastal watersheds affects the nearshore marine and estuarine waters. In southern California, coastal watersheds deliver water and associated constituents to the nearshore system in discrete pulses. To better understand the pulsed nature of these watersheds, frequency distributions of simulated runoff events are presented for: (1) three land use conditions (1929, 1998, 2050); (2) three time periods (all water years 1989‐2002), only El Nino years (1992, 1993, 1995, 1998); and only non‐El Nino years; and (3) three regions (watershed, uplands, and lowlands). At the watershed scale, there was a significant increase (>200%) in mean event runoff from 1929 to 2050 (0.4‐1.3 cm) due to localized urbanization, which shifted the dominant sources of runoff from the mountains in 1929 (78% of watershed runoff) to the coastal plane for 2050 conditions (51% of watershed runoff). Inter‐annual climate variability was strong in the rainfall and runoff frequency distributions, with mean event rainfall and runoff 66 and 60% larger in El Nino relative to non‐El Nino years. Combining urbanization and climate variability, 2050 land conditions resulted in El Nino years being five times more likely to produce large (>3.0 cm) runoff events relative to non‐El Nino years. Combining frequency distributions of event runoff with regional nutrient export relationships, we show that in El Nino years, one in five events produced runoff ≥2.5 cm and temporary nearshore nitrate and phosphate concentrations of 12 and 1.4 μM, respectively, or approximately 5‐10 times above ambient conditions. 相似文献
163.
Lei Zheng Jeroen Gerritsen John Beckman Jon Ludwig Sam Wilkes 《Journal of the American Water Resources Association》2008,44(6):1521-1536
Abstract: The eastern panhandle region of West Virginia is entirely within the Appalachian Ridge and Valley ecoregion. It is underlain by limestone in the eastern part and by shale and sandstone in the western part. Agricultural and urban development has affected the condition of the streams of this region. We examined samples from 165 stations in the Ridge and Valley, collected from 1998 to 2004. Land use, geological characteristics, physical and chemical parameters, and algal and macroinvertebrate assemblages were used to identify potential stressors that affect streams in the region. Our analyses indicated that both human land uses and ecoregional differences led to elevated nutrient concentrations in streams of the study areas. Multiple regression analyses indicated that both agricultural and urban land use in the watershed were associated with high nutrient concentrations (NO2+3, total nitrogen, and total phosphorus) in streams. These elevated nutrient concentrations have led to increased algal biomass, increased trophic state, and degradation of macroinvertebrate community in the streams. Values of the West Virginia Stream Condition Index, as well as several other benthic macroinvertebrate metrics, decreased with increased nutrient concentrations and conductivity, especially in the limestone region. When regional differences were partitioned out in the analysis, nutrient concentrations became the strongest stressor in the limestone region while conductivity exhibited less of an effect on macroinvertebrate metrics. Meanwhile, periphyton diagnostic metrics also responded to increased nutrient concentrations, suggesting nutrients could be a cause of biological degradation in the Eastern Ridge and Valley region. Multiple approaches and multiple lines of evidence (reference approach and stressor‐response approach) were applied to develop nutrient benchmarks for different geological regions in the study watershed. 相似文献
164.
Kuroshima KN Barreiros MA Lacava LA Costódio PF 《Environmental monitoring and assessment》2007,129(1-3):179-187
Since February 1999, the Municipal Wastewater Treatment Plant (MWTP) of Balneário Camboriú, Brazil, started a complementary
treatment with ClO2 application on its effluent. It was realized to minimize its impacts caused by increase of the population during summer.
This study was realized in order to verify the influence of this compound in the water quality and the environmental evaluations.
Samples of surface water were collected in this environment between January 1997 and June 2001 for chemical and microbiological
surveys. The results had shown that after application of ClO2, fecal coliforms were decreased about six times in the beach (2.3 × 103 to 3.5 × 102 MPN/100 ml) and three times in the river (3.3 × 104 to 1.0 × 104 MPN/100 ml), during summer time. NH4
+ showed an increase of about four times and 1.5 times, respectively, to beach and river. These results are showing the influence
of ClO2 on chemical and microbiological parameters. 相似文献
165.
东海春季赤潮前后沉积物-海水界面营养盐交换速率的研究 总被引:2,自引:1,他引:1
应用实验室培养法现场研究了3~5月东海硅藻赤潮发生前后10个站位的营养盐在沉积物-海水界面的交换,并应用连续函数拟合法计算了营养盐的界面交换速率.结果显示,NO-3-N在赤潮前向沉积物中汇聚[-1.33~-0.68 mmol/(m2·d)],赤潮后却基本由沉积物向海水中释放[-0.69~0.82 mmol/(m2·d)].NH+4-N在赤潮前后大都从沉积物中释放[-0.65~1.46 mmol/(m2·d)],赤潮后释放速率小于赤潮前.NO-2-N赤潮前后除Zc17站外都向沉积物中汇聚[-0.09~0.05 mmol/(m2·d)],赤潮后汇聚速率稍高.SiO2-3-Si在所有站位都由沉积物向海水释放[0.85~9.23 mmol/(m2·d)],其赤潮后速率高于赤潮前.PO3-4-P在赤潮前向沉积物中汇聚[-0.06~-0.01 mmol/(m2·d)],在赤潮后却由沉积物向海水中释放[0~1.26 mmol/(m2·d)].NO-3-N和PO3-4-P向东海近海沉积物的汇聚在春季不利于硅藻赤潮的暴发,但其在硅藻赤潮暴发后从沉积物的大量释放为后面紧接的大面积甲藻赤潮的暴发提供了重要的营养物质补充. 相似文献
166.
ABSTRACT: Land application of sewage sludge requires careful monitoring because of its potential for contamination of surface water and ground water. A rainfall simulator was used the investigate the effects of freshly applied sludge on infiltration, and on runoff of sediment and nutrients from agricultural crop lands. Rain was applied to 16 experimental field plots. A three-run sequence was used to simulate different initial moisture conditions. Runoff, sediment, and nutrient losses were monitored at the base of each plot during the simulated rainfall events. Sludge was surface applied and incorporated at conventionally-tilled plots and surface applied at no-till plots, at rates of 0, 75, 150 kg-N/ha. Steady-state infiltrability increased as a result of sludge application, although the no-till practice was more effective in increasing the infiltrability than the sludge application. No-till practices greatly reduced runoff, sediment, and nutrient losses from the sludge treated plots, relative to the conventional tillage practices. Incorporation of the sludge was effective in reducing nutrient yields at the conventionally-tilled plots. This effect was more pronounced during the third rainstorm, with wet initial conditions. Peak loadings of nutrients appeared during the rainstorm with wet initial conditions. 相似文献
167.
William G. Reay Daniel L. Gallagher George M. Simmons 《Journal of the American Water Resources Association》1992,28(6):1121-1134
ABSTRACT: Surface water, groundwater, and groundwater discharge quality surveys were conducted in Cherrystone Inlet, on Virginia's Eastern Shore. Shallow groundwater below agricultural fields had nitrate concentrations significantly higher than inlet surface waters and shallow groundwater underlying forested land. This elevated nitrate groundwater discharged to adjacent surface waters. Nearshore discharge rates of water across the sediment-water interface ranged from 0.02 to 3.69 liters·m?2·hr?1 during the surveys. The discharge was greatest nearshore at low tide periods, and decreased markedly with increasing distance offshore. Vertical hydraulic heads, Eh, and inorganic nitrogen flux in the sediments followed similar patterns. Nitrate was the predominant nitrogen species discharged nearshore adjacent to agricultural land use, changing to ammonium farther offshore. Sediment nitrogen fluxes were sufficient to cause observable impacts on surface water quality; nitrate concentrations were up to 20 times greater in areas of groundwater discharge than in the main stem inlet water. Based on DIN:DIP ratios, nitrogen contributions from direct groundwater discharge and tidal creek inputs appear to be of significant ecological importance. This groundwater discharge links land use activity and the quality of surface water, and therefore must be considered in selection of best management practices and water quality management strategies. 相似文献
168.
F. Richard Hauer Jack A. Stanford Mark S. Lorang 《Journal of the American Water Resources Association》2007,43(1):104-117
Abstract: The Crown of the Continent is one of the premiere ecosystems in North America containing Waterton‐Glacier International Peace Park, the Bob Marshall‐Great Bear‐Scapegoat Wilderness Complex in Montana, various Provincial Parks in British Columbia and Alberta, several national and state forest lands in the USA, and Crown Lands in Canada. The region is also the headwater source for three of the continent’s great rivers: Columbia, Missouri and Saskatchewan that flow to the Pacific, Atlantic and Arctic Oceans, respectively. Headwaters originate in high elevation alpine environs characterized by high snow accumulations in winter and rainstorms in summer. Most headwaters of the region contain high quality waters with few ions in solution and extremely low nutrient concentrations. Alpine streams have few species of aquatic organisms; however, they often possess rare species and have hydrogeomorphic features that make them vulnerable to climatic change. Subalpine and valley bottom streams of the Crown of the Continent Ecosystem (CCE) flow through well forested watersheds. Along the elevation gradient, the streams and rivers of the CCE flow through series of confining and nonconfining valleys resulting in distinct canyon and floodplain reaches. The alluvial floodplains are characterized by high species diversity and bioproduction maintained by the hydrologic linkages of habitats. The streams and rivers of the CCE have low nutrient concentrations, but may be significantly affected by wildfire, various resource extraction activities, such as logging or mining and exurban encroachment. Wildfire has been shown to increase nutrient loading in streams, both during a fire and then following the fire for as much as 5 years. Logging practices increase nutrient loading and the algal productivity of stream periphyton. Logging and associated roads are also known to increase sediment transport into Crown of the Continent streams directly affecting spawning success of native trout. The CCE is one of the fastest growing regions in the USA because of the many recreational amenities of the region. And, while the region has many remarkably pristine headwater streams and receiving rivers, there are many pending threats to water quality and quantity. One of the most urgent threats comes from the coal and gas fields in the northern part of the Crown of the Continent, where coal deposits are proposed for mountain‐top removal and open‐pit mining operations. This will have significant effects on the waters of the region, its native plants and animals and quality of life of the people. 相似文献
169.
W. H. Blake R. P. D. Walsh A. M. Sayer K. Bidin 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):615-623
Detailed information on post-logging sediment dynamics in tropical catchments is required for modelling downstream impacts
on communities and ecosystems. Sediment tracing methods, which are potentially useful in extending to the large catchment
scale and longer time scales, are tested in primary and selectively logged rainforest catchments of Sabah, Borneo. Selected
nutrient (P and N) and trace metal (Ni and Zn) concentrations are shown to discriminate surface, shallow subsurface and deep
subsurface sediment sources. Analysis of channel-stored fine-sediment samples and use of an unmixing model allow the relative
importance of these vertical sediment sources to be estimated and erosion processes to be inferred for catchments of contrasting
size. 相似文献
170.
Billy E. Johnson Terry K. Gerald 《Journal of the American Water Resources Association》2006,42(6):1503-1525
Abstract: A primary water quality problem caused by non-point source pollution (NPSP) is eutrophication, from excess nutrients in receiving water bodies. The control of nutrients arising from NPSP is difficult because the source areas can be hard to identify and typical treatment methods are infeasible due to the distributed nature of the pollutants. It may be possible to reduce nutrient related water quality problems through the restoration of highly disturbed watersheds with best management practices (BMPs). While restoration attempts may provide significant returns, they can be costly to implement and often are met with resistance in agricultural communities. Extending model results beyond the range of calibration to model future conditions such as for restoration scenarios requires the use of physically-based models that include the important processes that generate streamflow and material transport, uptake, loss, transformation, and recycling of nutrients and other material. The research and development objectives of the US. Army Engineer Research and Development Center (ERDC) in Vicksburg, Mississippi, are to develop a watershed assessment and management model to simulate transport, uptake, loss, transformation, and recycling of nutrients such as nitrogen and phosphorus and associated material such as sediment and organic matter. In this study we will discuss current efforts at the ERDC's Environmental Laboratory to develop a state-of-the-art watershed water quality model. 相似文献