Уточнить поиск
Результаты 171-180 из 1,310
Transfer functions for solid–solution partitioning of cadmium for Australian soils Полный текст
2011
de Vries, W. | McLaughlin, M.J. | Groenenberg, J.E.
Transfer functions for solid–solution partitioning of cadmium for Australian soils Полный текст
2011
de Vries, W. | McLaughlin, M.J. | Groenenberg, J.E.
To assess transport and ecotoxicological risks of metals, such as cadmium (Cd) in soils, models are needed for partitioning and speciation. We derived regression-based “partition-relations” based on adsorption and desorption experiments for main Australian soil types. First, batch adsorption experiments were carried out over a realistic range of dissolved Cd concentrations in agricultural soils in Australia. Results showed linear sorption relationships, implying the adequacy of using Kd values to describe partitioning. Desorption measurements were then carried out to assess in-situ Kd values and relate these to soil properties The best transfer functions for solid–solution partitioning were found for Kd values relating total dissolved Cd concentration to total soil Cd concentrations, accounting for the variation in pH, SOM contents and DOC concentrations. Model predictions compared well with measurements of an independent data set, but there was a tendency to underestimate dissolved Cd concentrations of highly polluted soils.
Показать больше [+] Меньше [-]Transfer functions for solid-solution partitioning of cadmium for Australian soils Полный текст
2011
De Vries, W. | McLaughlin, M. | Groenenberg, J.
To assess transport and ecotoxicological risks of metals, such as cadmium (Cd) in soils, models are needed for partitioning and speciation. We derived regression-based "partition-relations" based on adsorption and desorption experiments for main Australian soil types. First, batch adsorption experiments were carried out over a realistic range of dissolved Cd concentrations in agricultural soils in Australia. Results showed linear sorption relationships, implying the adequacy of using Kd values to describe partitioning. Desorption measurements were then carried out to assess in-situ Kd values and relate these to soil properties The best transfer functions for solid-solution partitioning were found for Kd values relating total dissolved Cd concentration to total soil Cd concentrations, accounting for the variation in pH, SOM contents and DOC concentrations. Model predictions compared well with measurements of an independent data set, but there was a tendency to underestimate dissolved Cd concentrations of highly polluted soils. | W. de Vries, M.J. McLaughlin, J.E. Groenenberg
Показать больше [+] Меньше [-]Effects of canopy–deposition interaction on H⁺ supply to soils in Pinus banksiana and Populus tremuloides ecosystems in the Athabasca oil sands region in Alberta, Canada Полный текст
2011
Jung, Kangho | Chang, Scott X. | Arshad, M.A (Charlie)
Soil acidification has been of concern in the oil sands region in Alberta due to increased acid deposition. Using the canopy budget model, and accounting for H⁺ canopy leaching by organic acids, we determined sources and sinks of H⁺ in throughfall in jack pine (Pinus banksiana) and trembling aspen (Populus tremuloides) stands in two watersheds from 2006 to 2009. In pine stands, H⁺ deposition was greater in throughfall than in bulk precipitation while the opposite was true in aspen stands. The annual H⁺ interception deposition was 148.8–193.8 and 49.7–70.0molcha⁻¹ in pine and aspen stands, respectively; while the annual H⁺ canopy leaching was 127.1–128.7 and 0.0–6.0molcha⁻¹, respectively. The greater H⁺ supply in pine stands was caused by greater interception deposition of SO₄ ²⁻ and organic acids released from the pine canopy. Such findings have significant implications for establishing critical loads for various ecosystems in the oil sands region.
Показать больше [+] Меньше [-]Nontarget analysis of polar contaminants in freshwater sediments influenced by pharmaceutical industry using ultra-high-pressure liquid chromatography–quadrupole time-of-flight mass spectrometry Полный текст
2011
Terzic, Senka | Ahel, Marijan
A comprehensive analytical procedure for a reliable identification of nontarget polar contaminants in aquatic sediments was developed, based on the application of ultra-high-pressure liquid chromatography (UHPLC) coupled to hybrid quadrupole time-of-flight mass spectrometry (QTOFMS). The procedure was applied for the analysis of freshwater sediment that was highly impacted by wastewater discharges from the pharmaceutical industry. A number of different contaminants were successfully identified owing to the high mass accuracy of the QTOFMS system, used in combination with high chromatographic resolution of UHPLC. The major compounds, identified in investigated sediment, included a series of polypropylene glycols (n = 3–16), alkylbenzene sulfonate and benzalkonium surfactants as well as a number of various pharmaceuticals (chlorthalidone, warfarin, terbinafine, torsemide, zolpidem and macrolide antibiotics). The particular advantage of the applied technique is its capability to detect less known pharmaceutical intermediates and/or transformation products, which have not been previously reported in freshwater sediments.
Показать больше [+] Меньше [-]Quantification of net carbon flux from plastic greenhouse vegetable cultivation: A full carbon cycle analysis Полный текст
2011
Wang, Yan | Xu, Hao | Wu, Xu | Zhu, Yimei | Gu, Baojing | Niu, Xiaoyin | Liu, Anqin | Peng, Changhui | Ge, Ying | Chang, Jie
Plastic greenhouse vegetable cultivation (PGVC) has played a vital role in increasing incomes of farmers and expanded dramatically in last several decades. However, carbon budget after conversion from conventional vegetable cultivation (CVC) to PGVC has been poorly quantified. A full carbon cycle analysis was used to estimate the net carbon flux from PGVC systems based on the combination of data from both field observations and literatures. Carbon fixation was evaluated at two pre-selected locations in China. Results suggest that: (1) the carbon sink of PGVC is 1.21 and 1.23 Mg C ha⁻¹ yr⁻¹ for temperate and subtropical area, respectively; (2) the conversion from CVC to PGVC could substantially enhance carbon sink potential by 8.6 times in the temperate area and by 1.3 times in the subtropical area; (3) the expansion of PGVC usage could enhance the potential carbon sink of arable land in China overall.
Показать больше [+] Меньше [-]BETR global – A geographically-explicit global-scale multimedia contaminant fate model Полный текст
2011
Macleod, Matthew | von Waldow, Harald | Tay, Pascal | Armitage, James M. | Wöhrnschimmel, Henry | Riley, William J. | McKone, Thomas E. | Hungerbuhler, Konrad
We present two new software implementations of the BETR Global multimedia contaminant fate model. The model uses steady-state or non-steady-state mass-balance calculations to describe the fate and transport of persistent organic pollutants using a desktop computer. The global environment is described using a database of long-term average monthly conditions on a 15°×15° grid. We demonstrate BETR Global by modeling the global sources, transport, and removal of decamethylcyclopentasiloxane (D5).
Показать больше [+] Меньше [-]First detection of an NSAID, flunixin, in sheep’s wool using GC–MS Полный текст
2011
Richards, Ngaio | Hall, Sarah | Scott, Karen | Harrison, Nancy
Exposure to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac resulted in the near extinction of three species of Gyps vultures on the Indian subcontinent. Other NSAIDs present in the environment, including flunixin, may pose a similar risk. In the course of a study to determine the feasibility of detecting NSAIDs in keratinous matrices (i.e., hair, nails and feathers) using GC–MS, wool opportunistically collected from a sheep treated with flunixin was analysed for residues. Flunixin was detected qualitatively in external wool wash and extract samples. While residues of veterinary agents and pesticides have previously been found in sheep’s wool, our preliminary investigation provides the first instance of an NSAID being detected in this matrix. Here we provide the sample preparation methods and GC–MS parameters used to enable further refinement as part of ongoing conservation and consumer quality control measures.
Показать больше [+] Меньше [-]Occurrence and profiles of organic sun-blocking agents in surface waters and sediments in Japanese rivers and lakes Полный текст
2011
Kameda, Yutaka | Kimura, Kumiko | Miyazaki, Motonobu
Sun-blocking agents including eight UV filters (UVF) and 10 UV light stabilizers (UVLS) were measured in water and sediment collected from 22 rivers, four sewage treatment plant effluents (STPE) and three lakes in Japan. Total sun blocking agents levels ranged from N.D. to 4928ng/L and from 2.0 to 3422μg/kg dry wt in surface water and in sediment, respectively. Benzyl salicylate, benzophenone-3, 2-ethyl hexyl-4-methoxycinnamte (EHMC) and octyl salicylate were dominant in surface water receiving wastewater effluents and STPE, although UV-328, benzophenone and EHMC were dominant in other surface water except background sites. Three UVF and nine UVLS were observed from all sediment and their compositions showed similar patterns with UV-328 and UV-234 as the most prevalent compounds. Homosalate, octocrylene, UV-326, UV-327, UV-328 and UV-234 were significantly correlated with Galaxolide® in sediments. Concentrations of UV-327 and UV-328 also had strong correlation between those of UV-326 in sediment.
Показать больше [+] Меньше [-]Biofilm responses to marine fish farm wastes Полный текст
2011
Sanz-Lázaro, Carlos | Navarrete-Mier, Francisco | Marín, Arnaldo
Biofilm responses to marine fish farm wastes Полный текст
2011
Sanz-Lázaro, Carlos | Navarrete-Mier, Francisco | Marín, Arnaldo
The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems.
Показать больше [+] Меньше [-]Biofilm responses to marine fish farm wastes Полный текст
2011
Sanz-Lázaro, Carlos | Navarrete Mier, Francisco | Marín, Arnaldo | Universidad de Alicante. Departamento de Ciencias del Mar y Biología Aplicada | Biología Marina
The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems. | This work was funded by the project AGL2004-08350-C02-01/ACU from the Ministerio de Ciencia y Tecnología, a predoctoral grant to C. S. from the Ministerio de Educación y Ciencia (Spain) and another predoctoral grant to F. N. from the ALBAN programme (EU).
Показать больше [+] Меньше [-]A rapidly equilibrating, thin film, passive water sampler for organic contaminants; characterization and field testing Полный текст
2011
St. George, Tiffany | Vlahos, Penny | Harner, Tom | Helm, Paul | Wilford, Bryony
Improving methods for assessing the spatial and temporal resolution of organic compound concentrations in marine environments is important to the sustainable management of our coastal systems. Here we evaluate the use of ethylene vinyl acetate (EVA) as a candidate polymer for thin-film passive sampling in waters of marine environments. Log KEVA₋W partition coefficients correlate well (r² = 0.87) with Log KOW values for selected pesticides and polychlorinated biphenyls (PCBs) where Log KEVA₋W = 1.04 Log KOW + 0.22. EVA is a suitable polymer for passive sampling due to both its high affinity for organic compounds and its ease of coating at sub-micron film thicknesses on various substrates. Twelve-day field deployments were effective in detecting target compounds with good precision making EVA a potential multi-media fugacity meter.
Показать больше [+] Меньше [-]Historical trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in three dated sediment cores from Mexico Полный текст
2011
Yunuén, Canedo-López | Vinicio, Macías-Zamora J. | Miguel Angel, Huerta-Diaz | Wee Kwong, Laval Liong | Sanchez-Cabeza, Joan Albert
This paper describes the first report of dioxins and furans (PCDDs/Fs) in sediment cores from Mexico. Sedimentation rates and vertical fluxes were estimated using ²¹⁰Pb dating. Two cores correspond to marine sediments and one to an endorheic lake. Concentrations of PCDDs/Fs found in the three sites are typical of non-impacted areas with low concentrations when compared to reference values. However the PCDDs/Fs sediment profiles show an increasing concentration trend in the upper core sections. This behavior is different from that found at many sites around the globe where diminishing concentrations have been reported. A strong predominance of OCDD was observed, and a comparison to typical composition profiles of industrial and other sources did not result in clear origin assignments for these measured compounds. We suggest that local sources may be responsible for the increase in concentration and, because these undetermined sources have not been curtailed, their importance is still growing.
Показать больше [+] Меньше [-]