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Résultats 181-190 de 1,273
Inorganic arsenic and trace elements in Ghanaian grain staples
2011
Adomako, Eureka E. | Williams, Paul N. | Deacon, Claire | Meharg, Andrew A.
A total of 549 samples of rice, maize, wheat, sorghum and millet were obtained from markets in Ghana, the EU, US and Asia. Analysis of the samples, originating from 21 countries in 5 continents, helped to establish global mean trace element concentrations in grains; thus placing the Ghanaian data within a global context. Ghanaian rice was generally low in potentially toxic elements, but high in essential nutrient elements. Arsenic concentrations in rice from US (0.22 mg/kg) and Thailand (0.15 mg/kg) were higher than in Ghanaian rice (0.11 mg/kg). Percentage inorganic arsenic content of the latter (83%) was, however, higher than for US (42%) and Thai rice (67%). Total arsenic concentration in Ghanaian maize, sorghum and millet samples (0.01 mg/kg) was an order of magnitude lower than in Ghanaian rice, indicating that a shift from rice-centric to multigrain diets could help reduce health risks posed by dietary exposure to inorganic As.
Afficher plus [+] Moins [-]Organophosphorus flame retardants and plasticizers in the atmosphere of the North Sea
2011
Möller, Axel | Xie, Zhiyong | Caba, Armando | Sturm, Renate | Ebinghaus, Ralf
Air samples collected in the German part of the North Sea from March to July 2010 were investigated for organophosphorus compounds (OPs) being applied as flame retardants and plasticizers. The ∑₈OPs concentration ranged from 110 to 1400 pg m⁻³ while tris(2-chloroisopropyl) phosphate (TCPP) dominated all samples with individual concentrations up to 1200 pg m⁻³. The highest concentrations were observed in continental air masses showing the high influence of industrialized regions including production sites on atmospheric emissions and concentrations. The occurrence of OPs even in oceanic/Arctic air masses shows that OPs can undergo long-range atmospheric transport. Dry particle-bound deposition fluxes from 9 to 240 ng m⁻² d⁻¹ for ∑₈OPs were estimated leading to a minimum annual flux of 710 ± 580 kg y⁻¹ OPs into the German North Sea. This study presents the first occurrence of OPs in the marine atmosphere together with important information on their long-range transport potential.
Afficher plus [+] Moins [-]Assessing the diurnal variability of pharmaceutical and personal care products in a full-scale activated sludge plant
2011
Salgado, R. | Marques, R. | Noronha, J.P. | Mexia, J.T. | Carvalho, G. | Oehmen, A. | Reis, M.A.M.
An intensive sampling campaign has been carried out in a municipal wastewater treatment plant (WWTP) to assess the dynamics of the influent pharmaceutical active compounds (PhAC) and musks. The mass loadings of these compounds in wastewater influents displayed contrasting diurnal variations depending on the compound. The musks and some groups of PhACs tended to follow a similar diurnal trend as compared to macropollutants, while the majority of PhACs followed either the opposite trend or no repeatable trend. The total musk loading to the WWTP was 0.74±0.25gd⁻¹, whereas the total PhAC mass loading was 84.7±63.8gd⁻¹. Unlike the PhACs, the musks displayed a high repeatability from one sampling day to the next. The range of PhAC loadings in the influent to WWTPs can vary several orders of magnitude from one day or week to the next, representing a challenge in obtaining data for steady-state modelling purposes.
Afficher plus [+] Moins [-]Mobile passive samplers: Concept for a novel mode of exposure
2011
Allan, Ian J. | Nilsson, Hans C. | Tjensvoll, Ingrid | Bradshaw, Clare | Næs, Kristoffer
Integrative passive sampling with devices such as semipermeable membrane devices generally relies on rigs for month-long static exposures in water. We evaluate here whether mobile exposures of passive samplers can provide reliable estimates of dissolved contaminant concentrations. Mobile exposures were obtained by towing samplers fastened to the end of a benthic trawl net. Significant and reproducible absorption of polycyclic aromatic hydrocarbons during 5 h-long deployments was made possible by high sampling rates resulting from high water turbulences during towing at 1.2–1.5 knots. Sampling rates (72–215 L d⁻¹) estimated from the dissipation of performance reference compounds were supported by in situ calibration with samplers exposed for a 30 days in the vicinity of the test site. Higher fluoranthene and pyrene absorption in samplers exposed to the trawling-induced sediment plume could be attributed to desorption from re-suspended sediments. This mode of exposure has the potential to be used in monitoring programmes.
Afficher plus [+] Moins [-]Arsenite toxicity and uptake rate of rice (Oryza sativa L.) in vivo
2011
Hoffmann, Holger | Schenk, Manfred K.
Toxicity threshold of arsenite on intact rice seedlings was determined and arsenite uptake characteristics were investigated using non-toxic concentrations of arsenite. The arsenite toxicity threshold was 2.4μM arsenite which reduced growth by 10% (EC₁₀). The two highest arsenite levels induced wilting of seedlings and reduced both, transpiration rate and net photosynthetic rate. Arsenic content in plant tissue increased up to 10.7μM arsenite and then declined with increasing arsenite concentration in the treatment solution. The contents of Si, P, K, and of micronutrients Cu, Fe, Mn and Zn in shoot d.m. were reduced by arsenite levels≥5.3μM. In the non-toxic range, arsenite uptake rate was linearly related to arsenite concentration. High arsenite levels reduced growth without being taken up which might be due to increasing binding of arsenite to proteins at the outer side of the plasmalemma.
Afficher plus [+] Moins [-]Long-term environmental monitoring of persistent organic pollutants and metals in a chemical/petrochemical area: Human health risks
2011
Nadal, Martí | Schuhmacher, Marta | Domingo, José L.
Organic pollutants such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polycyclic aromatic hydrocarbons (PAHs), as well as some metals are periodically monitored in soil and vegetation samples collected in Tarragona County (Spain). We here report the temporal trends of the concentrations of the above pollutants between the initial survey (2002) and that recently (2009) performed. The area under evaluation was divided into 4 sections (chemical, petrochemical, urban/residential and unpolluted). In general terms, urban soils presented the highest concentrations of PCDD/Fs, PCNs and PAHs, confirming that traffic is a very important emission source of these pollutants. In addition, substantially higher levels of PAHs and some metals were found in vegetation samples from the petrochemical complex. The assessment of health risks of these contaminants indicated that the current concentrations of micropollutants did not mean additional non-carcinogenic or cancer risks for the population living in the zone.
Afficher plus [+] Moins [-]Arsenic and Mn levels in Isaza (Gymnogobius isaza) during the mass mortality event in Lake Biwa, Japan
2011
Hirata, Sawako Horai | Hayase, Daisuke | Eguchi, Akifumi | Itai, Takaaki | Nomiyama, Kei | Isobe, Tomohiko | Agusa, Tetsuro | Ishikawa, Toshiyuki | Kumagai, Michio | Tanabe, Shinsuke
The present study measured the concentrations of 25 elements (Li, Mg, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) in the whole body of Isaza which is an endemic fish species to Lake Biwa, Japan, and compared the values in the specimens from the mass mortality Isaza (MMI) and normal fresh Isaza (NFI). The mean levels of Mn and total As (T-As) were relatively higher in MMI than in NFI. In the T-As, highly toxic inorganic As was detected in MMI. Moreover we found Mn and As concentrations in surface sediment were extremely high and temporally increased. From all these results, we could infer that the dissolution of Mn and As from surface sediment of Lake Biwa might have been one of the cause for the mass mortality of Isaza.
Afficher plus [+] Moins [-]Nitrogen deposition effects on Mediterranean-type ecosystems: An ecological assessment
2011
Ochoa-Hueso, Raúl | Allen, Edith B. | Branquinho, Cristina | Cruz Mínguez, Cristina | Dias, Teresa | Fenn, Mark E. | Manrique, Esteban | Pérez-Corona, M Esther | Sheppard, Lucy J. | Stock, William D.
We review the ecological consequences of N deposition on the five Mediterranean regions of the world. Seasonality of precipitation and fires regulate the N cycle in these water-limited ecosystems, where dry N deposition dominates. Nitrogen accumulation in soils and on plant surfaces results in peaks of availability with the first winter rains. Decoupling between N flushes and plant demand promotes losses via leaching and gas emissions. Differences in P availability may control the response to N inputs and susceptibility to exotic plant invasion. Invasive grasses accumulate as fuel during the dry season, altering fire regimes. California and the Mediterranean Basin are the most threatened by N deposition; however, there is limited evidence for N deposition impacts outside of California. Consequently, more research is needed to determine critical loads for each region and vegetation type based on the most sensitive elements, such as changes in lichen species composition and N cycling.
Afficher plus [+] Moins [-]Contamination by arsenic and other trace elements of tube-well water along the Mekong River in Lao PDR
2011
Chanpiwat, Penradee | Sthiannopkao, Suthipong | Cho, Kyung Hwa | Kim, Kyoung-Woong | San, Vibol | Suvanthong, Boukeo | Vongthavady, Chantha
Arsenic and other trace element concentrations were determined for tube-well water collected in the Lao PDR provinces of Attapeu, Bolikhamxai, Champasak, Savannakhet, Saravane, and Vientiane. Water samples, especially from floodplain areas of central and southern Laos, were significantly contaminated not only with As, but with B, Ba, Mn, U, and Fe as well. Total As concentrations ranged from <0.5μgL⁻¹ to 278μgL⁻¹, with over half exceeding the WHO guideline of 10μgL⁻¹. 46% of samples, notably, were dominated by As(III). Samples from Vientiane, further north, were all acceptable except on pH, which was below drinking water limits. A principal component analysis found associations between general water characteristics, As, and other trace elements. Causes of elevated As concentrations in Lao tube wells were considered similar to those in other Mekong River countries, particularly Cambodia and Vietnam, where young alluvial aquifers give rise to reducing conditions.
Afficher plus [+] Moins [-]Arsenic distribution in soils and plants of an arsenic impacted former mining area
2011
Otones, V. | Álvarez-Ayuso, E. | García-Sánchez, A. | Santa Regina, I. | Murciego, A.
A mining area affected by the abandoned exploitation of an arsenical tungsten deposit was studied in order to assess its arsenic pollution level and the feasibility of native plants for being used in phytoremediation approaches. Soil and plant samples were collected at different distances from the polluting sources and analysed for their As content and distribution. Critical soil total concentrations of As were found, with values in the range 70–5330mgkg⁻¹ in the uppermost layer. The plant community develops As tolerance by exclusion strategies. Of the plant species growing in the most polluted site, the shrubs Salix atrocinerea Brot. and Genista scorpius (L.) DC. exhibit the lowest bioaccumulation factor (BF) values for their aerial parts, suggesting their suitability to be used with revegetation purposes. The species Scirpus holoschoenus L. highlights for its important potential to stabilise As at root level, accumulating As contents up to 3164mgkg⁻¹.
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