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991.
George P. Ingersoll M. Alisa Mast Donald H. Campbell David W. Clow Leora Nanus John T. Turk 《Atmospheric environment (Oxford, England : 1994)》2008,42(24):6098-6113
Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993–2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions. Seasonal Kendall tests were used to evaluate trends at individual sites.Significant trends occurred during the period in wetfall and snowpack concentrations and deposition, and in precipitation. For the comparison, trends in concentrations of ammonium, nitrate, and sulfate for the two networks were in fair agreement. In several cases, increases in ammonium and nitrate concentrations, and decreases in sulfate concentrations for both wetfall and snowpack were consistent in the three subregions. However, deposition patterns between wetfall and snowpack more often were opposite, particularly for ammonium and nitrate. Decreases in ammonium and nitrate deposition in wetfall in the central and southern rockies subregions mostly were moderately significant (p<0.11) in constrast to highly significant increases in snowpack (p<0.02). These opposite trends likely are explained by different rates of declining precipitation during the recent drought (1999–2004) and increasing concentration. Furthermore, dry deposition was an important factor in total deposition of nitrogen in the region. Sulfate deposition decreased with moderate to high significance in all three subregions in both wetfall and snowpack. Precipitation trends consistently were downward and significant for wetfall, snowpack, and snow-telemetry data for the central and southern rockies subregions (p<0.03), while no trends were noted for the Northern Rockies subregion. 相似文献
992.
Tuncel SG Oztas NB Erduran MS 《Journal of the Air & Waste Management Association (1995)》2008,58(9):1240-1249
Air pollution and groundwater pollution in conjunction with agricultural activity were investigated in Antayla province on the Turkish Mediterranean coast. The air pollution was investigated in terms of gas-phase nitric acid (HNO3), sulfur dioxide (SO2), ammonia (NH3), and particulate matter for a 6-month period in the atmosphere using a "filter pack" system, which was developed and optimized in our laboratory. Ozone was measured by using an automated analyzer. Among all of the gas-phase pollutants, HNO3 had the lowest concentration (0.42 microg x m(-3)) followed by NH3. Agricultural activities seem to be the major source of observed NH3 in the air. The current state of water pollution was investigated in terms of organochlorine and organophosphorus pesticides around the greenhouses, in which mainly tomato, pepper, and eggplant are cultivated. Water samples were collected from 40 points, 28 of which were wells and 12 of which were surface water. The pesticide concentrations in water samples were determined by means of solid-phase extraction (SPE) followed by a gas chromatography (GC)-electron capture detector (ECD)/nitrogen phosphorus detector (NPD) system. In general, surface water samples were more polluted by the pesticides than groundwater samples. The most frequently observed pesticides were chlorpyriphos (57%) and aldrin (79%) in groundwater, and chlorpyriphos (75%), aldrin, and endosulfan sulfate (83%) in surface water samples. The highest concentrations were observed for fenamiphos (394.8 ng/L) and aldrin (68.51 ng/L) in groundwater, and dichlorvos (322.2 ng/L) and endosulfan sulfate (89.5 ng/L) in surface water samples. At least one pesticide had a concentration above the health limit in 38% of all the water samples analyzed. 相似文献
993.
Long-term survey of heavy-metal pollution, biofilm contamination and diatom community structure in the Riou Mort watershed, South-West France 总被引:4,自引:0,他引:4
Morin S Duong TT Dabrin A Coynel A Herlory O Baudrimont M Delmas F Durrieu G Schäfer J Winterton P Blanc G Coste M 《Environmental pollution (Barking, Essex : 1987)》2008,151(3):532-542
In a metal-polluted stream in the Riou Mort watershed in SW France, periphytic biofilm was analyzed for diatom cell densities and taxonomic composition, dry weight and metal bio-accumulation (cadmium and zinc). Periphytic diatom communities were affected by the metal but displayed induced tolerance, seen through structural impact (dominance of small, adnate species) as well as morphological abnormalities particularly in the genera Ulnaria and Fragilaria. Species assemblages were characterized by taxa known to occur in metal-polluted environments, and shifts in the community structure expressed seasonal patterns: high numbers of Eolimna minima, Nitzschia palea and Pinnularia parvulissima were recorded in Summer and Autumn, whereas the species Surirella brebissonii, Achnanthidium minutissimum, Navicula lanceolata and Surirella angusta were dominant in Winter and Spring. Commonly used indices such as the Shannon diversity index and Specific Pollution Sensitivity Index reflected the level of pollution and suggest seasonal periodicity, the lowest diversities being observed in Summer. 相似文献
994.
Mohr S Feibicke M Berghahn R Schmiediche R Schmidt R 《Environmental pollution (Barking, Essex : 1987)》2008,152(3):530-542
Metazachlor is a frequently used herbicide with concentrations in surface waters up to 100 microg L(-1). A long-term mesocosm study was performed in order to investigate effects on stream and pond communities also regarding recovery. Single metazachlor doses of 5, 20, 80, 200, and 500 microg L(-1) were given and the aquatic communities monitored for 140 days. In this paper, special attention is paid to the plankton response and the results of the entire study are summarised. Metazachlor strongly affected the stream and pond mesocosm communities at concentrations higher than 5 microg L(-1). Direct negative effects were most prominent for chlorophytes whereas diatoms and cryptophytes seemed insensitive. The effects on zooplankton were caused by changes in habitat structure due to the strong decline of macrophytes. The slow degradation of metazachlor combined with the absence of recovery in both chlorophytes and macrophytes is likely to cause long-lasting effects on aquatic ecosystems. 相似文献
995.
Roberts DA Johnston EL Müller S Poore AG 《Environmental pollution (Barking, Essex : 1987)》2008,152(1):153-162
Epifaunal communities associated with macroalgae were exposed to storm water pulses using a custom made irrigation system. Treatments included Millipore freshwater, freshwater spiked with trace metals and seawater controls to allow for the relative importance of freshwater inundation, trace metals and increased flow to be determined. Experimental pulses created conditions similar to those that occur following real storm water events. Brief storm water pulses reduced the abundance of amphipods and gastropods. Freshwater was the causative agent as there were no additional effects of trace metals on the assemblages. Laboratory assays indicated that neither direct nor latent mortality was likely following experimental pulses and that epifauna readily avoid storm water. Indirect effects upon epifauna through salinity-induced changes to algal habitats were not found in field recolonisation experiments. Results demonstrate the importance of examining the effects of pulsed contaminants under realistic exposure conditions and the need to consider ecologically relevant endpoints. 相似文献
996.
Use of principal component analysis to profile temporal and spatial variations of chlorinated solvent concentration in groundwater 总被引:2,自引:0,他引:2
This work aims at evaluating spatial distribution patterns of concentration variations for chlorinated solvents in groundwater, based on principal component analysis and geographic information system (GIS) tools. The study investigates long-time series of chlorinated solvent concentrations in groundwater measured for 18 contaminated industrial sites. The characterization of contaminant plumes and delineation of pollutant sources are essential for choosing appropriate monitoring and remediation strategies, as contaminated groundwaters are characterized by complex patterns of spatial and temporal concentration variability, with wide unpredictable fluctuations over time. The present work describes the results of a new exploratory statistical method called the Variability Index Method (VIM) applied to environmental data to assess the performance of using concentration variations as molecular tracers to reveal aquifer dynamics, industrial impacts, and point sources for contamination plumes. The application of this method provides a useful assessment of controls over contaminant concentration variations as well as support for remediation techniques. 相似文献
997.
Hernández-Allica J Becerril JM Garbisu C 《Environmental pollution (Barking, Essex : 1987)》2008,152(1):32-40
A hydroponic screening method was used to identify high biomass crop plants with the ability to accumulate metals. Highest values of shoot accumulation were found in maize cv. Ranchero, rapeseed cv. Karat, and cardoon cv. Peralta for Pb (18 753 mg kg(-1)), Zn (10 916 mg kg(-1)), and Cd (242 mg kg(-1)), respectively. Subsequently, we tested the potential of these three cultivars for the phytoextraction of a metal spiked compost, finding out that, in cardoon and maize plants, increasing Zn and Cd concentrations led to lower values of root and shoot DW. By contrast, rapeseed shoot growth was not significantly affected by Cd concentration. Finally, a metal polluted soil was used to check these cultivars' phytoextraction capacity. Although the soil was phytotoxic enough to prevent the growth of cardoon and rapeseed plants, maize plants phytoextracted 3.7 mg Zn pot(-1). We concluded that the phytoextraction performance of cultivars varies depending on the screening method used. 相似文献
998.
Wetlands as principal zones of methylmercury production in southern Louisiana and the Gulf of Mexico region 总被引:2,自引:0,他引:2
Hall BD Aiken GR Krabbenhoft DP Marvin-Dipasquale M Swarzenski CM 《Environmental pollution (Barking, Essex : 1987)》2008,154(1):124-134
It is widely recognized that wetlands, especially those rich in organic matter and receiving appreciable atmospheric mercury (Hg) inputs, are important sites of methylmercury (MeHg) production. Extensive wetlands in the southeastern United States have many ecosystem attributes ideal for promoting high MeHg production rates; however, relatively few mercury cycling studies have been conducted in these environments. We conducted a landscape scale study examining Hg cycling in coastal Louisiana (USA) including four field trips conducted between August 2003 and May 2005. Sites were chosen to represent different ecosystem types, including: a large shallow eutrophic estuarine lake (Lake Pontchartrain), three rivers draining into the lake, a cypress-tupelo dominated freshwater swamp, and six emergent marshes ranging from a freshwater marsh dominated by Panicum hemitomon to a Spartina alterniflora dominated salt marsh close to the Gulf of Mexico. We measured MeHg and total Hg (THg) concentrations, and ancillary chemical characteristics, in whole and filtered surface water, and filtered porewater. Overall, MeHg concentrations were greatest in surface water of freshwater wetlands and lowest in the profundal (non-vegetated) regions of the lake and river mainstems. Concentrations of THg and MeHg in filtered surface water were positively correlated with the highly reactive, aromatic (hydrophobic organic acid) fraction of dissolved organic carbon (DOC). These results suggest that DOC plays an important role in promoting the mobility, transport and bioavailability of inorganic Hg in these environments. Further, elevated porewater concentrations in marine and brackish wetlands suggest coastal wetlands along the Gulf Coast are key sites for MeHg production and may be a principal source of MeHg to foodwebs in the Gulf of Mexico. Examining the relationships among MeHg, THg, and DOC across these multiple landscape types is a first step in evaluating possible links between key zones for Hg(II)-methylation and the bioaccumulation of mercury in the biota inhabiting the Gulf of Mexico region. 相似文献
999.
Spatial and temporal patterns of metal mobilisation from former water-powered, Pb working sites in a suburban area of Sheffield (UK) were investigated. Twelve time-integrated mass flux samplers were strategically deployed over two contrasting campaign periods (summer and winter). Suspended sediment samples were characterised magnetically and subjected to metal analysis. Metal levels in the upper River Sheaf showed a marked spatial and temporal variability. Pb concentrations in particular were relatively high (maximum 2132 mg kg(-1)). Their distribution tended to reflect the historical contamination of the valley by 17th to 19th century industry, especially during summer high discharge conditions. The mean suspended sediment Pb concentration (803 mg kg(-1)) exceeds contamination guidelines. It is unclear whether ground remediation of one of the seven floodplain sites in the catchment has been successful. The river is still affected by the legacy of at least two other Pb working sites. 相似文献
1000.
Nitrogen deposition increases the acquisition of phosphorus and potassium by heather Calluna vulgaris 总被引:1,自引:0,他引:1
Rowe EC Smart SM Kennedy VH Emmett BA Evans CD 《Environmental pollution (Barking, Essex : 1987)》2008,155(2):201-207
Increased plant productivity due to nitrogen pollution increases the strength of the global carbon sink, but is implicated in plant diversity loss. However, modelling and experimental studies have suggested that these effects are constrained by availability of other nutrients. In a survey of element concentrations in Calluna vulgaris across an N deposition gradient in the UK, shoot concentrations of N and more surprisingly phosphorus and potassium were positively correlated with N deposition; tissue N/P ratio even decreased with N deposition. Elevated P and K concentrations possibly resulted from improved acquisition due to additional enzyme production or mycorrhizal activity. Heather occurs on organic soils where nutrient limitations are likely due to availability constraints rather than small stocks. However, if this effect extends to other plant and soil types, effects of N deposition on C sinks and plant competition may not be as constrained by availability of other nutrients as previously proposed. 相似文献