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Результаты 431-440 из 1,273
Inputs of antifouling paint-derived dichlorodiphenyltrichloroethanes (DDTs) to a typical mariculture zone (South China): Potential impact on aquafarming environment
2011
Yu, Huan-Yun | Shen, Ru-Lang | Liang, Yan | Cheng, Hefa | Zeng, E. Y. (Eddy Y.)
Existing evidence indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paints were an important source of DDT residues to mariculture zones. However, the magnitude of the impact on aquafarming environment has remained largely unknown. In the present study, the concentrations of DDT and its metabolites (designated as DDXs) were determined in harbor sediment and antifouling paint samples collected from a typical mariculture zone in South China. Compositional and concentration correlation analyses implicated the DDT-containing antifouling paints for fishing boat maintenance as an important source of DDT in the mariculture zone. The annual emission of DDXs to the study region was estimated at 0.58tons/yr. Furthermore, a comparison of the expected DDT loadings in pelagic fish and field measurements indicated that fish feed especially trash fish was a major source of DDTs in the fish body. Nevertheless, the use of DDT-containing antifouling paints should be limited to prevent further deterioration in aquafarming environment.
Показать больше [+] Меньше [-]Bioaccumulation and trophic transfer of dioxins in marine copepods and fish
2011
Zhang, Qiong | Yang, Liuyan | Wang, Wen-Xiong
Despite the great concerns about dioxins in the marine environments, the biokinetics and bioaccumulation of these compounds in marine organisms remains little known. Using radioactive tracers the aqueous uptake, dietary assimilation efficiency, and elimination of dioxins were measured in marine phytoplankton, copepods and seabream. The calculated uptake rate constant of dioxins decreased with increasing trophic levels, whereas the dietary assimilation efficiency (AE) was 28.5–57.6% in the copepods and 36.6–70.2% in the fish. The dietary AE was highly dependent on the food concentrations and food type. The elimination rate constant of dioxin in the copepods varied with different exposure pathways as well as food concentration and food type. Biokinetic calculation showed that dietary accumulation was the predominant pathway for dioxin accumulation in marine copepods and fish. Aqueous uptake can be an important pathway only when the bioconcentration of dioxins in the phytoplankton was low.
Показать больше [+] Меньше [-]To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution
2011
Shi, Jiyan | Abid, Aamir D. | Kennedy, Ian M. | Hristova, Krassimira R. | Silk, Wendy K.
CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer–Emmett–Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6mgL⁻¹ soluble copper or by 1.0mgL⁻¹ CuO-NP that released only 0.16mgL⁻¹ soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0mgL⁻¹ CuO-NP, but not in the comparable 0.2mgL⁻¹ soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content.
Показать больше [+] Меньше [-]Dechlorane Plus (DP) in air and plants at an electronic waste (e-waste) site in South China
2011
Chen, She-Jun | Tian, Mi | Wang, Jing | Shi, Tian | Luo, Yong | Luo, Xiao-Jun | Mai, Bi-Xian
Air and foliage samples (Eucalyptus spp. and Pinus massoniana Lamb.) were collected from e-waste and reference sites in South China and analyzed for Dechlorane Plus (DP) and two dechlorinated DPs. DP concentrations in the air were 13.1–1794 pg/m³ for the e-waste site and 0.47–35.7 pg/m³ for the reference site, suggesting the recycling of e-waste is an important source of DP to the environment. Plant DP, with concentrations of 0.45–51.9 ng/g dry weight at the e-waste site and 0.09–2.46 ng/g at the reference site, exhibited temporal patterns similar to the air DP except for pine needle at the reference site. The air-plant exchange of DP could be described with the two-compartment model. Anti-Cl₁₁ DP was measured in most air and plant samples from the e-waste site. The ratios of anti-Cl₁₁ DP to anti-DP in the air and plants may indicate the preferential uptake of dechlorinated DP by plant compared with DP.
Показать больше [+] Меньше [-]Fate and effects of anthropogenic chemicals in mangrove ecosystems: A review
2011
Lewis, Michael | Pryor, Rachel | Wilking, Lynn
The scientific literature for fate and effects of non-nutrient contaminant concentrations is skewed for reports describing sediment contamination and bioaccumulation for trace metals. Concentrations for at least 22 trace metals have been reported in mangrove sediments. Some concentrations exceed sediment quality guidelines suggesting adverse effects. Bioaccumulation results are available for at least 11 trace metals, 12 mangrove tissues, 33 mangrove species and 53 species of mangrove-habitat biota. Results are specific to species, tissues, life stage, and season and accumulated concentrations and bioconcentration factors are usually low. Toxicity tests have been conducted with 12 mangrove species and 8 species of mangrove-related fauna. As many as 39 effect parameters, most sublethal, have been monitored during the usual 3 to 6 month test durations. Generalizations and extrapolations for toxicity between species and chemicals are restricted by data scarcity and lack of experimental consistency. This hinders chemical risk assessments and validation of effects-based criteria.
Показать больше [+] Меньше [-]Trophically available metal – A variable feast
2011
Rainbow, P. S. | Luoma, Samuel N. | Wang, Wen-Xiong
Assimilation of trace metals by predators from prey is affected by the physicochemical form of the accumulated metal in the prey, leading to the concept of a Trophically Available Metal (TAM) component in the food item definable in terms of particular subcellular fractions of accumulated metal. As originally defined TAM consists of soluble metal forms and metal associated with cell organelles, the combination of separated fractions which best explained particular results involving a decapod crustacean predator feeding on bivalve mollusc tissues. Unfortunately TAM as originally defined has subsequently frequently been used in the literature as an absolute description of that component of accumulated metal that is trophically available in all prey to all consumers. It is now clear that what is trophically available varies between food items, consumers and metals. TAM as originally defined should be seen as a useful starting hypothesis, not as a statement of fact.
Показать больше [+] Меньше [-]Wastewater treatment plants and landfills emit volatile methyl siloxanes (VMSs) to the atmosphere: Investigations using a new passive air sampler
2011
Cheng, Yu | Shoeib, Mahiba | Ahrens, Lutz | Harner, Tom | Ma, Jianmin
Volatile methyl siloxanes (VMSs) are a class of chemicals with an increasing range of applications and widespread distribution in the environment. Passive air samplers (PAS) comprising sorbent-impregnated polyurethane-foam (SIP) disks were first calibrated and then deployed around two wastewater treatment plants (WWTPs) and at two landfill sites to investigate inputs of VMSs to air. SIP-derived air concentrations for ΣVMSs (ng/m³) at background sites on the perimeter of the WWTP were 479±82.3 and comparable to results for the upwind samples at the landfills (333±194). Order of magnitude higher concentrations of ΣVMSs (ng/m³) were found for on-site samples at the WWTPs (3980±2620) and landfills (4670±3360). Yearly emissions (kg/yr) to air were estimated and ranged from 60–2100 and 80–250, respectively, for the cyclic VMSs. These findings demonstrate and quantify for the first time, waste sector emissions of VMSs to the atmosphere.
Показать больше [+] Меньше [-]Concentration of trace elements in feathers of three Antarctic penguins: Geographical and interspecific differences
2011
Jerez, Silvia | Motas, Miguel | Palacios, María José | Valera, Francisco | Cuervo, José Javier | Barbosa, Andrés
Antarctica is often considered as one of the last pristine regions, but it could be affected by pollution at global and local scale. Concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were determinated by ICP-MS in feathers (n = 207 individuals) of gentoo, chinstrap and Adélie penguin collected in 8 locations throughout the Antarctic Peninsula (2006–2007). The highest levels of several elements were found in samples from King George Island (8.08, 20.29 and 1.76 μg g⁻¹ dw for Cr, Cu and Pb, respectively) and Deception Island (203.13, 3.26 and 164.26 μg g⁻¹ dw for Al, Mn and Fe, respectively), where probably human activities and large-scale transport of pollutants contribute to increase metal levels. Concentrations of Cr, Mn, Cu, Se or Pb, which are similar to others found in different regions of the world, show that some areas in Antarctica are not utterly pristine.
Показать больше [+] Меньше [-]Truncated Lévy flights and agenda-based mobility are useful for the assessment of personal human exposure
2011
Schlink, Uwe | Ragas, Ad M.J.
Receptor-oriented approaches can assess the individual-specific exposure to air pollution. In such an individual-based model we analyse the impact of human mobility to the personal exposure that is perceived by individuals simulated in an exemplified urban area. The mobility models comprise random walk (reference point mobility, RPM), truncated Lévy flights (TLF), and agenda-based walk (RPMA). We describe and review the general concepts and provide an inter-comparison of these concepts. Stationary and ergodic behaviour are explained and applied as well as performance criteria for a comparative evaluation of the investigated algorithms. We find that none of the studied algorithm results in purely random trajectories. TLF and RPMA prove to be suitable for human mobility modelling, because they provide conditions for very individual-specific trajectories and exposure. Suggesting these models we demonstrate the plausibility of their results for exposure to air-borne benzene and the combined exposure to benzene and nonane.
Показать больше [+] Меньше [-]Impact of atmospheric deposition of anthropogenic and natural trace metals on Northwestern Mediterranean surface waters: A box model assessment
2011
Heimbürger, Lars-Eric | Migon, Christophe | Cossa, Daniel
Under stratified oligotrophic conditions (May–November), the surface mixed layer of the Northwestern Mediterranean constitutes a homogeneous water volume of 10–30m depth. In other respects, the mean residence time of Ligurian surface waters (0–200m) is 102 days. It is therefore possible to quantify the extent to which atmospheric deposition of trace metals affects surface waters. On the basis of literature data on anthropogenic and natural trace metals, we demonstrate that the ratios between total seawater labile atmospheric deposition during 102 days (Δc) and dissolved TM concentrations in Ligurian surface waters (c) illustrate the impact of atmospheric deposition on surface seawater (Δc/c). High ratios indicate surface TM enrichments, while low ratios indicate surface TM depletion, due to the quasi-complete sorption and removal of TMs by plankton during spring bloom. The simple box model proposed here may be used for other marine regions where hydrodynamical and physico-chemical constraints are well defined.
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