خيارات البحث
النتائج 291 - 300 من 3,240
Organophosphorus flame retardants and plasticizers: Sources, occurrence, toxicity and human exposure النص الكامل
2015
Wei, Gao-Ling | Li, Ding-Qiang | Zhuo, Mu-Ning | Liao, Yi-Shan | Xie, Zhen-Yue | Guo, Tai-Long | Li, Jun-Jie | Zhang, Si-Yi | Liang, Zhi-Quan
Due to the restricted use and ban of brominated flame retardants, organophosphorus compounds (OPs), extensively used as flame retardants and plasticizers, are ubiquitous in various environmental compartments worldwide. The present study shows that the release of OPs from a wide variety of commercial products and wastewater discharge might be considered as primary emission sources and that high potential of long-range atmospheric transport and persistence of OPs would be responsible for their presence in various matrices on a global scale. The occurrence and environmental behaviors of OPs in diverse matrices (e.g., dust, air, water, sediment, soil and biota) are reviewed. Human exposures to OPs via dermal contact, dust ingestion, inhalation and dietary intake are comprehensively evaluated. Finally, this study identifies gaps in the existing issues and generates a future agenda for the emerging contaminants OPs.
اظهر المزيد [+] اقل [-]Effects of PAHs and dioxins on the earthworm Eisenia andrei: A multivariate approach for biomarker interpretation النص الكامل
2015
Sforzini, Susanna | Moore, Michael N. | Boeri, Marta | Bencivenga, Mauro | Viarengo, Aldo
In this study, a battery of biomarkers was utilised to evaluate the stress syndrome induced in the earthworm Eisenia andrei by exposure to environmentally realistic concentrations of benzo[a]pyrene (B[a]P) and 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) in OECD soil. The set of tests was then employed to assess the toxicity of field soils contaminated with organic xenobiotic compounds (such as PAHs, dioxins and PCBs). The results highlighted an impairment of immune and metabolic functions and genotoxic damage in worms exposed also to lower bioavailable concentrations of toxic chemicals. Multivariate analysis of biomarker data showed that all different contaminated soils had a detrimental effect on the earthworms. A separation between temporal and concentration factors was also evident for B[a]P and TCDD treatments; and field contaminated soils were further differentiated reflecting a diverse contamination. Multivariate analysis also demonstrated that lysosomal membrane stability can be considered a prognostic indicator for worm health status.
اظهر المزيد [+] اقل [-]Using foliar and forest floor mercury concentrations to assess spatial patterns of mercury deposition النص الكامل
2015
Blackwell, Bradley D. | Driscoll, Charles T.
We evaluated spatial patterns of mercury (Hg) deposition through analysis of foliage and forest floor samples from 45 sites across Adirondack Park, NY. Species-specific differences in foliar Hg were evident with the lowest concentrations found in first-year conifer needles and highest concentrations found in black cherry (Prunus serotina). For foliage and forest floor samples, latitude and longitude were negatively correlated with Hg concentrations, likely because of proximity to emission sources, while elevation was positively correlated with Hg concentrations. Elemental analysis showed moderately strong, positive correlations between Hg and nitrogen concentrations. The spatial pattern of Hg deposition across the Adirondacks is similar to patterns of other contaminants that originate largely from combustion sources such as nitrogen and sulfur. The results of this study suggest foliage can be used to assess spatial patterns of Hg deposition in small regions or areas of varied topography where current Hg deposition models are too coarse to predict deposition accurately.
اظهر المزيد [+] اقل [-]Commuter exposure to particulate matter and particle-bound PAHs in three transportation modes in Beijing, China النص الكامل
2015
Yan, Caiqing | Zheng, Mei | Yang, Qiaoyun | Zhang, Qunfang | Qiu, Xinghua | Zhang, Yanjun | Fu, Huaiyu | Li, Xiaoying | Zhu, Tong | Zhu, Yifang
Exposure to fine and ultrafine particles as well as particulate polycyclic aromatic hydrocarbons (PAHs) by commuters in three transportation modes (walking, subway and bus) were examined in December 2011 in Beijing, China. During the study period, real-time measured median PM2.5 mass concentration (PMC) for walking, riding buses and taking the subway were 26.7, 32.9 and 56.9 μg m−3, respectively, and particle number concentrations (PNC) were 1.1 × 104, 1.0 × 104 and 2.2 × 104 cm−3. Commuters were exposed to higher PNC in air-conditioned buses and aboveground-railway, but higher PMC in underground-subway compared to aboveground-railway. PNC in roadway modes (bus and walking) peaked at noon, but was lower during traffic rush hours, negatively correlated with PMC. Toxic potential of particulate-PAHs estimated based on benzo(a)pyrene toxic equivalents (BaP TEQs) showed that walking pedestrians were subjected to higher BaP TEQs than bus (2.7-fold) and subway (3.6-fold) commuters, though the highest PMC and PNC were observed in subway.
اظهر المزيد [+] اقل [-]The relative importance of diet-related and waterborne effects of copper for a leaf-shredding invertebrate النص الكامل
2015
Zubrod, J.P. | Englert, D. | Rosenfeldt, R.R. | Wolfram, J. | Lüderwald, S. | Wallace, D. | Schnetzer, N. | Schulz, R. | Bundschuh, M.
Copper (Cu) exposure can increase leaf-associated fungal biomass, an important food component for leaf-shredding macroinvertebrates. To test if this positive nutritional effect supports the physiological fitness of these animals and to assess its importance compared to waterborne toxicity, we performed a 24-day-bioassay in combination with a 2×2 factorial design using the amphipod shredder Gammarus fossarum and a field-relevant Cu concentration of 25 μg/L (n = 65). Waterborne toxicity was negligible, while gammarids fed leaves exposed to Cu during microbial colonization exhibited a near-significant impairment in growth (∼30%) and a significantly reduced lipid content (∼20%). These effects appear to be governed by dietary uptake of Cu, which accumulated in leaves as well as gammarids and likely overrode the positive nutritional effect of the increased fungal biomass. Our results suggest that for adsorptive freshwater contaminants dietary uptake should be evaluated already during the registration process to safeguard the integrity of detritus-based ecosystems.
اظهر المزيد [+] اقل [-]On the use of small and cheaper sensors and devices for indicative citizen-based monitoring of respirable particulate matter النص الكامل
2015
Jovašević-Stojanović, Milena | Bartonova, Alena | Topalović, Dušan | Lazović, Ivan | Pokrić, Boris | Ristovski, Zoran
Respirable particulate matter present in outdoor and indoor environments is a health hazard. The particle concentrations can quickly change, with steep gradients on short temporal and spatial scales, and their chemical composition and physical properties vary considerably. Existing networks of aerosol particle measurements consist of limited number of monitoring stations, and mostly aim at assessment of compliance with air quality legislation regulating mass of particles of varying sizes. These networks can now be supplemented using small portable devices with low-cost sensors for assessment of particle mass that may provide higher temporal and spatial resolution if we understand the capabilities and characteristics of the data they provide. This paper overviews typical currently available devices and their characteristics. In addition it is presented original results of measurement and modelling in the aim of one low-cost PM monitor validation.
اظهر المزيد [+] اقل [-]Will technological modernization for power generation at an oil refinery diminish the risks from air pollution to the Atlantic Rainforest in Cubatão, SE Brazil? النص الكامل
2015
Nakazato, Ricardo K. | Rinaldi, Mirian C.S. | Domingos, Marisa
We assessed the level of atmospheric contamination by S, N and metals before, during and after the installation of a new thermoelectric plant that provides power to an oil refinery in Cubatão, SE Brazil. We measured the foliar accumulation in Lolium multiflorum “Lema” with the aim of evaluating risks to the Atlantic Rainforest that grows in the region. Al, Co, Cr, Cu, K, N, Ni, S, V and Zn were appropriate markers of the new air contamination profile associated with the modern technology. With the exception of V, the leaf contents of these elements significantly increased between the pre-operation to post-operation phases (Al, Co, N, K, S), or only during the transition phase (Zn, Cu, Cr, Ni), and returned to the previous levels after the total shutdown of the old system. Therefore, the expected environmental gain was not achieved with the installation of the new technology.
اظهر المزيد [+] اقل [-]Reconnaissance of contaminants in larval Pacific lamprey (Entosphenus tridentatus) tissues and habitats in the Columbia River Basin, Oregon and Washington, USA النص الكامل
2015
Nilsen, Elena B. | Hapke, Whitney B. | McIlraith, Brian | Markovchick, Dennis
Pacific lampreys (Entosphenus tridentatus) have resided in the Columbia River Basin for millennia and have great ecological and cultural importance. The role of habitat contamination in the recent decline of the species has rarely been studied and was the main objective of this effort. A wide range of contaminants (115 analytes) was measured in sediments and tissues at 27 sites across a large geographic area of diverse land use. This is the largest dataset of contaminants in habitats and tissues of Pacific lamprey in North America and the first study to compare contaminant bioburden during the larval life stage and the anadromous, adult portion of the life cycle. Bioaccumulation of pesticides, flame retardants, and mercury was observed at many sites. Based on available data, contaminants are accumulating in larval Pacific lamprey at levels that are likely detrimental to organism health and may be contributing to the decline of the species.
اظهر المزيد [+] اقل [-]Combined thermal and herbicide stress in functionally diverse coral symbionts النص الكامل
2015
van Dam, J.W. | Uthicke, S. | Beltran, V.H. | Mueller, J.F. | Negri, A.P.
Most reef building corals rely on symbiotic microalgae (genus Symbiodinium) to supply a substantial proportion of their energy requirements. Functional diversity of different Symbiodinium genotypes, endorsing the host with physiological advantages, has been widely reported. Yet, the influence of genotypic specificity on the symbiont's susceptibility to contaminants or cumulative stressors is unknown. Cultured Symbiodinium of presumed thermal-tolerant clade D tested especially vulnerable to the widespread herbicide diuron, suggesting important free-living populations may be at risk in areas subjected to terrestrial runoff. Co-exposure experiments where cultured Symbiodinium were exposed to diuron over a thermal stress gradient demonstrated how fast-growing clade C1 better maintained photosynthetic capability than clade D. The mixture toxicity model of Independent Action, considering combined thermal stress and herbicide contamination, revealed response additivity for inhibition of photosynthetic yield in both tested cultures, emphasizing the need to account for cumulative stressor impacts in ecological risk assessment and resource management.
اظهر المزيد [+] اقل [-]Canopy-level stomatal narrowing in adult Fagus sylvatica under O3 stress – Means of preventing enhanced O3 uptake under high O3 exposure? النص الكامل
2015
Matyssek, R. | Baumgarten, M. | Hummel, U. | Häberle, K.-H. | Kitao, M. | Wieser, G.
Spatio-temporally consistent O3 doses are demonstrated in adult Fagus sylvatica from the Kranzberg Forest free-air fumigation experiment, covering cross-canopy and whole-seasonal scopes through sap flow measurement. Given O3-driven closure of stomata, we hypothesized enhanced whole-tree level O3 influx to be prevented under enhanced O3 exposure. Although foliage transpiration rate was lowered under twice-ambient O3 around noon by 30% along with canopy conductance, the hypothesis was falsified, as O3 influx was raised by 25%. Nevertheless, the twice-ambient/ambient ratio of O3 uptake was smaller by about 20% than that of O3 exposure, suggesting stomatal limitation of uptake. The O3 response was traceable from leaves across branches to the canopy, where peak transpiration rates resembled those of shade rather than sun branches. Rainy/overcast-day and nightly O3 uptake is quantified and discussed. Whole-seasonal canopy-level validation of modelled with sap flow-derived O3 flux becomes available in assessing O3 risk for forest trees.
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