خيارات البحث
النتائج 211 - 220 من 4,023
Microplastic pollution in the Greenland Sea: Background levels and selective contamination of planktivorous diving seabirds
2016
Amélineau, F. | Bonnet, D. | Heitz, O. | Mortreux, V. | Harding, A.M.A. | Karnovsky, N. | Walkusz, W. | Fort, J. | Grémillet, D.
Microplastics have been reported everywhere around the globe. With very limited human activities, the Arctic is distant from major sources of microplastics. However, microplastic ingestions have been found in several Arctic marine predators, confirming their presence in this region. Nonetheless, existing information for this area remains scarce, thus there is an urgent need to quantify the contamination of Arctic marine waters. In this context, we studied microplastic abundance and composition within the zooplankton community off East Greenland. For the same area, we concurrently evaluated microplastic contamination of little auks (Alle alle), an Arctic seabird feeding on zooplankton while diving between 0 and 50 m. The study took place off East Greenland in July 2005 and 2014, under strongly contrasted sea-ice conditions. Among all samples, 97.2% of the debris found were filaments. Despite the remoteness of our study area, microplastic abundances were comparable to those of other oceans, with 0.99 ± 0.62 m−3 in the presence of sea-ice (2005), and 2.38 ± 1.11 m−3 in the nearby absence of sea-ice (2014). Microplastic rise between 2005 and 2014 might be linked to an increase in plastic production worldwide or to lower sea-ice extents in 2014, as sea-ice can represent a sink for microplastic particles, which are subsequently released to the water column upon melting. Crucially, all birds had eaten plastic filaments, and they collected high levels of microplastics compared to background levels with 9.99 and 8.99 pieces per chick meal in 2005 and 2014, respectively. Importantly, we also demonstrated that little auks took more often light colored microplastics, rather than darker ones, strongly suggesting an active contamination with birds mistaking microplastics for their natural prey. Overall, our study stresses the great vulnerability of Arctic marine species to microplastic pollution in a warming Arctic, where sea-ice melting is expected to release vast volumes of trapped debris.
اظهر المزيد [+] اقل [-]Cross-sectional association between exposure to particulate matter and inflammatory markers in the Japanese general population: NIPPON DATA2010
2016
Michikawa, Takehiro | Okamura, Tomonori | Nitta, Hiroshi | Nishiwaki, Yuji | Takebayashi, Toru | Ueda, Kayo | Kadota, Aya | Fujiyoshi, Akira | Ohkubo, Takayoshi | Ueshima, Hirotsugu | Okayama, Akira | Miura, Katsuyuki
A suggestive mechanism behind the association between particulate matter and cardiovascular disease is inflammatory response. Earlier population-based studies investigating the association between particulate matter and inflammatory biological markers, in particular C-reactive protein (CRP), showed inconsistent results. In addition, evidence from the Asian population, in which CRP levels are typically lower than those observed in Western populations, was sparse. We examined the cross-sectional association between short- and long-term exposure to particulate matter and inflammatory markers, including high-sensitivity CRP (hs-CRP) and white blood cell (WBC) count, in a representative population of Japanese community dwellers (NIPPON DATA2010). We analysed data from 2360 participants (1002 men and 1358 women), aged 20 years or older, who resided in 300 randomly selected districts (222 public health centre areas) throughout Japan. We used background concentrations of suspended particulate matter (SPM, defined as particles with a 100% cut-off level at 10 μm aerodynamic diameter) and co-pollutants within the public health centre area. A logistic regression model was applied to estimate odds ratios (ORs) of elevated hs-CRP (> 0.3 mg/dl) or WBC (> 9000/μl). Since smoking is an important confounding factor, we firstly included this in the models, and additionally conducted the analyses after excluding current smokers. The one-month average concentration of SPM was positively associated with hs-CRP (OR per 10 μg/m3 increase in SPM = 1.42, 95% confidence interval = 1.00–2.04), and high exposure to SPM on the day of blood draw was associated with increased WBC count, after excluding current smokers (OR = 1.13, 1.01–1.28). Similar association patterns were observed for ozone. In conclusion, exposure to particulate matter was associated with inflammatory markers in the general Japanese population. Systemic inflammation may play a role in the link between particulate matter and cardiovascular disease.
اظهر المزيد [+] اقل [-]Are intertidal soft sediment assemblages affected by repeated oil spill events? A field-based experimental approach
2016
Sandrini-Neto, Leonardo | Martins, César C. | Lana, Paulo C.
This study investigates the impact of repeated diesel spills on the structure of intertidal macrofaunal assemblages of a subtropical estuary. Three frequencies of exposure events were compared against two dosages of oil in a factorial experiment with asymmetrical controls. Hypotheses were tested to distinguish between (i) the overall effect of oil spills, (ii) the effect of diesel dosage via different exposure regimes, and (iii) the effect of time since last spill. Repeated oil spills dramatically altered the overall structure of assemblages and reduced the total density of macrofauna and densities of dominant taxa. Increasing the frequency of oil spills negatively affected macrofauna. In general, frequent low-dosage oil spills were more deleterious than infrequent high-dosage ones. However, increases in densities of some taxa, mainly the gastropod Heleobia australis, were observed in response to infrequent spills. Our results highlight the importance of repeated exposure events in determining the extent of oil impacts.
اظهر المزيد [+] اقل [-]Elevated CO2 increases glomalin-related soil protein (GRSP) in the rhizosphere of Robinia pseudoacacia L. seedlings in Pb- and Cd-contaminated soils
2016
Jia, Xia | Zhao, Yonghua | Liu, Tuo | Huang, Shuping | Chang, Yafei
Glomalin-related soil protein (GRSP), which contains glycoproteins produced by arbuscular mycorrhizal fungi (AMF), as well as non-mycorrhizal-related heat-stable proteins, lipids, and humic materials, is generally categorized into two fractions: easily extractable GRSP (EE-GRSP) and total GRSP (T-GRSP). GRSP plays an important role in soil carbon (C) sequestration and can stabilize heavy metals such as lead (Pb), cadmium (Cd), and manganese (Mn). Soil contamination by heavy metals is occurring in conjunction with rising atmospheric CO2 in natural ecosystems due to human activities. However, the response of GRSP to elevated CO2 combined with heavy metal contamination has not been widely reported. Here, we investigated the response of GRSP to elevated CO2 in the rhizosphere of Robinia pseudoacacia L. seedlings in Pb- and Cd-contaminated soils. Elevated CO2 (700 μmol mol−1) significantly increased T- and EE- GRSP concentrations in soils contaminated with Cd, Pb or Cd + Pb. GRSP contributed more carbon to the rhizosphere soil organic carbon pool under elevated CO2 + heavy metals than under ambient CO2. The amount of Cd and Pb bound to GRSP was significantly higher under elevated (compared to ambient) CO2; and elevated CO2 increased the ratio of GRSP-bound Cd and Pb to total Cd and Pb. However, available Cd and Pb in rhizosphere soil under increased elevated CO2 compared to ambient CO2. The combination of both metals and elevated CO2 led to a significant increase in available Pb in rhizosphere soil compared to the Pb treatment alone. In conclusion, increased GRSP produced under elevated CO2 could contribute to sequestration of soil pollutants by adsorption of Cd and Pb.
اظهر المزيد [+] اقل [-]Concern-driven integrated approaches for the grouping, testing and assessment of nanomaterials
2016
Landsiedel, Robert
NM's potential to induce adverse effects in humans or the environment is being addressed in numerous research projects, and methods and tools for NM hazard identification and risk assessment are advancing. This article describes how integrated approaches for the testing and assessment of NMs can ensure the safety of nanomaterials, while adhering to the 3Rs principle.
اظهر المزيد [+] اقل [-]The way forward for risk assessment of nanomaterials in solid media
2016
Scott-Fordsmand, Janeck J. | Peijnenburg, Willie | Amorim, Mónica J.B. | Landsiedel, Robert | Oorts, Koen
There is an urgent need for sufficient knowledge to allow reliable assessment of the risks associated with engineered nanomaterials (ENPs). Significant advances in basic understanding of nano safety have been made, but there is still no clear systematic basis for risk-related research, and major uncertainties remain in the absence of uniform procedures. The following papers provide the guidance on how to proceed within the area of fate and hazard assessment, and how this links into grouping, testing and risk assessment of nanomaterials. This guidance is coupled with an industrial view on the most important research areas for nanomaterials.
اظهر المزيد [+] اقل [-]Does temporal variation of mercury levels in Arctic seabirds reflect changes in global environmental contamination, or a modification of Arctic marine food web functioning?
2016
Fort, Jérôme | Grémillet, David | Traisnel, Gwendoline | Amélineau, Françoise | Bustamante, Paco
Studying long-term trends of contaminants in Arctic biota is essential to better understand impacts of anthropogenic activities and climate change on the exposure of sensitive species and marine ecosystems. We concurrently measured temporal changes (2006–2014) in mercury (Hg) contamination of little auks (Alle alle; the most abundant Arctic seabird) and in their major zooplankton prey species (Calanoid copepods, Themisto libellula, Gammarus spp.). We found an increasing contamination of the food-chain in East Greenland during summer over the last decade. More specifically, bird contamination (determined by body feather analyses) has increased at a rate of 3.4% per year. Conversely, bird exposure to Hg during winter in the northwest Atlantic (determined by head feather analyses) decreased over the study period (at a rate of 1.5% per year), although winter concentrations remained consistently higher than during summer. By combining mercury levels measured in birds and zooplankton to isotopic analyses, our results demonstrate that inter-annual variations of Hg levels in little auks reflect changes in food-chain contamination, rather than a reorganization of the food web and a modification of seabird trophic ecology. They therefore underline the value of little auks, and Arctic seabirds in general, as bio-indicators of long-term changes in environmental contamination.
اظهر المزيد [+] اقل [-]Effect assessment of engineered nanoparticles in solid media – Current insight and the way forward
2016
Amorim, Mónica J.B. | Roca, Carlos P. | Scott-Fordsmand, Janeck J.
Engineered Nanoparticles (ENPs) present novel/added challenges to the established effect assessment modus operandi, requiring an update of used methods. ENPs are dimensionally and physically different from conventional chemicals, which imply that the metrics with which we relate effect and the type of effect responses are different from that of the conventional approach. Effects on organisms are often preceded by changes on the sub-organismal level (cell, genes), dedicated tools have vast potential to detect earlier (and link to) effects on higher levels of organization. High-throughput screening (HTS) is rapid, cost-effective and specific. One way forward is to link HTS to population outcomes, targeting a systems toxicology approach. Although the benefits of integrating various levels of information may seem obvious, this is an even more decisive aspect when rapid answers are needed for ENPs. Here we rank the available tools/methods, highlight main study gaps and list priority needs and the way forward.
اظهر المزيد [+] اقل [-]Hazardous indoor CO2 concentrations in volcanic environments
2016
Viveiros, Fátima | Gaspar, J. L. (João L.) | Ferreira, Teresa | Silva, Catarina
Carbon dioxide is one of the main soil gases released silently and permanently in diffuse degassing areas, both in volcanic and non-volcanic zones. In the volcanic islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at Furnas village, inside the caldera of the quiescent Furnas Volcano (S. Miguel Island). Hazardous CO2 concentrations were detected not only underground, but also at the ground floor level. Multivariate regression analysis was applied to the CO2 and environmental time series recorded between April 2008 and March 2010 at Furnas village. The results show that about 30% of the indoor CO2 variation is explained by environmental variables, namely barometric pressure, soil water content and wind speed. The highest indoor CO2 concentrations were recorded during bad weather conditions, characterized by low barometric pressure together with rainfall periods and high wind speed. In addition to the spike-like changes observed on the CO2 time series, long-term oscillations were also identified and appeared to represent seasonal variations. In fact, indoor CO2 concentrations were higher during winter period when compared to the dry summer months. Considering the permanent emission of CO2 in various volcanic regions of the world, CO2 hazard maps are crucial and need to be accounted by the land-use planners and authorities.
اظهر المزيد [+] اقل [-]Assessment of status of three water bodies in Serbia based on tissue metal and metalloid concentration (ICP-OES) and genotoxicity (comet assay)
2016
Sunjog, Karolina | Kolarević, Stoimir | Kračun-Kolarević, Margareta | Višnjić-Jeftić, Željka | Skorić, Stefan | Gačić, Zoran | Lenhardt, Mirjana | Vasić, Nebojša | Vuković-Gačić, Branka
Metals and metalloids are natural components of the biosphere, which are not produced per se by human beings, but whose form and distribution can be affected by human activities. Like all substances, they are a contaminant if present in excess compared to background levels and/or in a form that would not normally occur in the environment. Samples of liver, gills, gonads and muscle from European chub, Squalius cephalus, were analyzed for Al, As, B, Ba, Cr, Cu, Fe, Hg, Mn, Mo, Sr and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) to highlight the importance of tissue selection in monitoring research. The comet assay or single cell gel electrophoresis (SCGE) was selected as an in vivo genotoxicity assay, a rapid and sensitive method for measuring genotoxic effects in blood, liver and gills of the European chub. Microscopic images of comets were scored using Comet IV Computer Software (Perceptive Instruments, UK).The objective of our study was to investigate two reservoirs, Zlatar and Garasi, and one river, Pestan by: (i) determining and comparing metal and metalloid concentrations in sediment, water and tissues of European chub: liver, gills, muscle and gonads (ii) comparing these findings with genotoxicity of water expressed through DNA damage of fish tissues.A clear link between the level of metals in water, sediment and tissues and between metal and genotoxicity levels at examined sites was not found. This suggests that other xenobiotics (possibly the organic compounds), contribute to DNA damage.
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