خيارات البحث
النتائج 1461 - 1470 من 1,535
Establishing potential links between the presence of alkylphenolic compounds and the benthic community in a European river basin
2012
Brix, Rikke | López-Doval, Julio | Ricart, Marta | Guasch, Helena | de Alda, Miren Lopez | Muñoz, Isabel | Orendt, Claus | Romaní i Cornet, Anna M. | Sabater, Sergi | Barceló, Damià
INTRODUCTION: Concentrations of alkylphenolic compounds (APCs) in water and sediments were related to the composition and functional descriptors of the benthic community (biofilm and macroinvertebrates). MATERIALS AND METHODS: Samples were collected in four sampling campaigns at seven sampling points in the lower Llobregat catchment area (NE Spain). Water and sediment samples underwent chemical target analysis for nine APCs, which are known to disrupt the endocrine system. RESULTS AND DISCUSSIONS: APCs were the main stressors on the diatom community but not on the macroinvertebrate community. CONCLUSIONS: Benthic invertebrates were mostly affected by the general physicochemical water characteristics (where conductivity was a surrogate). Nonylphenol only had an influence on the diatom community in water but not in the remaining compartments, probably because of the low concentrations observed in the environment.
اظهر المزيد [+] اقل [-]Utilization of urban sewage sludge: Chinese perspectives
2012
Chen, H. | Yan, S-H. | Ye, Z-L. | Meng, H-J. | Zhu, Y-G.
PURPOSE: Urbanization and industrialization in China has resulted in a dramatic increase in the volume of wastewater and sewage sludge produced from wastewater treatment plants. Problems associated with sewage sludge have attracted increasing attention from the public and urban planners. How to manage sludge in an economically and environmentally acceptable manner is one of the critical issues that modern societies are facing. METHODS: Sludge treatment systems consist of thickening, dewatering, and several different alternative main treatments (anaerobic digestion, aerobic digestion, drying, composting, and incineration). Agricultural application, landfill, and incineration are the principal disposal methods for sewage sludge in China. However, sewage sludge disposal in the future should focus on resource recovery, reducing environmental impacts and saving economic costs. RESULTS: The reuse of biosolids in all scenarios can be environmentally beneficial and cost-effective. Anaerobic digestion followed by land application is the preferable options due to low economic and energy costs and material reuse. CONCLUSION: It is necessary to formulate a standard suitable for the utilization of sewage sludge in China.
اظهر المزيد [+] اقل [-]Application of molecularly imprinted and non-imprinted polymers for removal of emerging contaminants in water and wastewater treatment: a review
2012
Murray, Audrey | Örmeci, Banu
Over the past decade, several studies have reported trace levels of endocrine disrupting compounds, pharmaceuticals, and personal care products in surface waters, drinking water, and wastewater effluents. There has also been an increased concern about the ecological and human health impact of these contaminants, and their removal from water and wastewater has become a priority. Traditional treatment processes are limited in their ability to remove emerging contaminants from water, and there is a need for new technologies that are effective and feasible. This paper presents a review on recent research results on molecularly imprinted (MIP) and non-imprinted (NIP) polymers and evaluates their potential as a treatment method for the removal of emerging contaminants from water and wastewater. It also discusses the relative benefits and limitations of using MIP or NIP for water and wastewater treatment. MIP, and in particular NIP, offer promising applications for wastewater treatment, but their toxicity and possible health effects should be carefully studied before they are considered for drinking water treatment. More research is also required to determine how best to incorporate MIP and NIP in treatment plants.
اظهر المزيد [+] اقل [-]Biodegradability and ecotoxicitiy of tramadol, ranitidine, and their photoderivatives in the aquatic environment
2012
Bergheim, Marlies | Gieré, Reto | Kümmerer, Klaus
PURPOSE: This study was designed to assess the fate and the overall potential impacts of the widely prescribed drugs ranitidine and tramadol after their introduction into the aquatic environment. METHODS: The probability to detect these two drugs in the aquatic environment was studied by analyzing their abiotic and biotic degradation properties. For this purpose, samples were irradiated with different light sources, and three widely used biodegradability tests from the OECD series, the closed bottle test (OECD 301 D), the manometric respirometry test (OECD 301 F) and the Zahn–Wellens test (OECD 302 B), were conducted. The ecotoxicity of the photolytically formed transformation products was assessed by performing the bacterial growth inhibition test (EN ISO 10712). Furthermore, quantitative structure–activity relationship analysis and a risk analysis based on the calculation of the predicted environmental concentrations have also been conducted to assess the environmental risk potential of the transformation products. The possible formation of stable products by microbial or photolytical transformation has been investigated with DOC and LC-MS analytics. RESULTS: In the present study, neither ranitidine, nor tramadol, nor their photoderivatives were found to be readily or inherently biodegradable according to test guidelines. The photolytic transformation was faster under a UV lamp compared to the reaction under an Xe lamp with a spectrum that mimics sunlight. No chronic toxicity against bacteria was found for ranitidine or its photolytic decomposition products, but a low toxicity was detected for the resulting mixture of the photolytic transformation products of tramadol. CONCLUSIONS: The study demonstrates that transformation products may have a higher environmental risk potential than the respective parent compounds.
اظهر المزيد [+] اقل [-]Comparison of micrometeorological and two-film estimates of air–water gas exchange for alpha-hexachlorocyclohexane in the Canadian archipelago
2012
Wong, Fiona | Jantunen, Liisa M. | Papakyriakou, Tim | Staebler, Ralf | Stern, Gary A. | Bidleman, Terry F.
The air–sea gas exchange of alpha-hexachlorocyclohexane (α-HCH) in the Canadian Arctic was estimated using a micrometeorological approach and the commonly used Whitman two-film model. Concurrent shipboard measurements of α-HCH in air at two heights (1 and 15 m) and in surface seawater were conducted during the Circumpolar Flaw Lead study in 2008. Sampling was carried out during eight events in the early summer time when open water was encountered. The micrometeorological technique employed the vertical gradient in air concentration and the wind speed to estimate the flux; results were corrected for atmospheric stability using the Monin–Obukhov stability parameter. The Whitman two-film model used the concentrations of α-HCH in surface seawater, in bulk air at 1 and 15 m above the surface, and the Henry’s law constant adjusted for temperature and salinity to derive the flux. Both approaches showed that the overall net flux of α-HCH was from water to air. Mean fluxes calculated using the micrometeorological technique ranged from −3.5 to 18 ng m−2 day−1 (mean 7.4), compared to 3.5 to 14 ng m−2 day−1 (mean 7.5) using the Whitman two-film model. Flux estimates for individual events agreed in direction and within a factor of two in magnitude for six of eight events. For two events, fluxes estimated by micrometeorology were zero or negative, while fluxes estimated with the two-film model were positive, and the reasons for these discrepancies are unclear. Improvements are needed to shorten air sampling times to ensure that stationarity of meteorological conditions is not compromised over the measurement periods. The micrometeorological technique could be particularly useful to estimate fluxes of organic chemicals over water in situations where no water samples are available.
اظهر المزيد [+] اقل [-]Functional traits of soil invertebrates as indicators for exposure to soil disturbance
2012
Hedde, Mickaël | Van Oort, Folkert | Lamy, Isabelle
We tested a trait-based approach to link a soil disturbance to changes in invertebrate communities. Soils and macro-invertebrates were sampled in sandy soils contaminated by long-term wastewater irrigation, adding notably organic matter and trace metals (TM). We hypothesized that functional traits of invertebrates depict ways of exposure and that exposure routes relate to specific TM pools. Geophages and soft-body invertebrates were chosen to inform on exposure by ingestion or contact, respectively. Trait-based indices depicted more accurately effects of pollution than community density and diversity did. Exposure by ingestion had more deleterious effects than by contact. Both types of exposed invertebrates were influenced by TM, but geophages mainly responded to changes in soil organic matter contents. The trait-based approach requires to be applied in various conditions to uncorrelate specific TM impacts from those of other environmental factors.
اظهر المزيد [+] اقل [-]Seawater carbonate chemistry and copepod Centropages tenuiremis feeding, filtering and respiration rate during experiments, 2012
2012
Li, Wei | Gao, Kunshan
Climate change mediates marine chemical and physical environments and therefore influences marine organisms. While increasing atmospheric CO2 level and associated ocean acidification has been predicted to stimulate marine primary productivity and may affect community structure, the processes that impact food chain and biological CO2 pump are less documented. We hypothesized that copepods, as the secondary marine producer, may respond to future changes in seawater carbonate chemistry associated with ocean acidification due to increasing atmospheric CO2 concentration. Here, we show that the copepod, Centropages tenuiremis, was able to perceive the chemical changes in seawater induced under elevated CO2 concentration (>1700 µatm, pH < 7.60) with avoidance strategy. The copepod's respiration increased at the elevated CO2 (1000 µatm), associated acidity (pH 7.83) and its feeding rates also increased correspondingly, except for the initial acclimating period, when it fed less. Our results imply that marine secondary producers increase their respiration and feeding rate in response to ocean acidification to balance the energy cost against increased acidity and CO2 concentration.
اظهر المزيد [+] اقل [-]Lead/Calcium profiles in the common time window 1770-2010 of the three Arctica islandica shells
2012
Krause-Nehring, Jacqueline | Brey, Thomas | Thorrold, Simon R
In the study, we establish centennial records of anthropogenic lead pollution at different locations in the North Atlantic (Iceland, USA, and Europe) by means of lead deposited in shells of the long-lived bivalve Arctica islandica. Due to local oceanographic and geological conditions we conclude that the lead concentrations in the Icelandic shell reflect natural influxes of lead into Icelandic waters. In comparison, the lead profile of the US shell is clearly driven by anthropogenic lead emissions transported from the continent to the ocean by westerly surface winds. Lead concentrations in the European North Sea shell, in contrast, are dominantly driven by local lead sources resulting in a much less conspicuous 1970s gasoline lead peak. In conclusion, the lead profiles of the three shells are driven by different influxes of lead, and yet, all support the applicability of Pb/Ca analyses of A. islandica shells to reconstruct location specific anthropogenic lead pollution.
اظهر المزيد [+] اقل [-]Toxicity of East Sumatra river sediments - bacterial luminescence, brine shrimp and Acetylcholinesterase Inhibition Tests
2012
Scholz, Bettina | Ziehe, Daniel | Pivetta, Lucinela A. | Pielok, Nils | Liebezeit, Gerd
Water pollution in Asia: the urgent need for prevention and monitoring.
2012
Evans, A. | Hanjra, Munir A. | Jiang, Y. | Qadir, Manzoor | Drechsel, Pay