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Resultados 1371-1380 de 2,498
Urban Market Gardening in Africa: Foliar Uptake of Metal(loid)s and Their Bioaccessibility in Vegetables; Implications in Terms of Health Risks
2014
Uzu, Gaëlle | Schreck, Eva | Xiong, Tiantian | Macouin, Mélina | Lévêque, Thibaut | Fayomi, Benjamin | Dumat, Camille
Urban market gardening in Africa is suffering from increasing environmental contamination due to sources of contamination as varied as traffic, industry, and agriculture practices. A field study was therefore conducted to determine the global influence of the polluted environment (atmosphere, soil, and irrigation waters) on vegetable quality in a large urban-farming area. For leafy vegetables collected in 15 ha of squatted land belonging to the international airport of Cotonou, total concentrations of metal(loid)s measured in consumed parts of Lactuca sativa L. and Brassica oleracea were 52.6–78.9, 0.02–0.3, 0.08–0.22, 12.7–20.3, 1.8–7.9, and 44.1–107.8 mg kg⁻¹for Pb, Cd, As, Sb, Cu, and Zn, respectively. Human gastric bioaccessibility of the metal(loid)s was measured, and the obtained values varied according to the considered metal(loid) and the plant species. The results identified values that are commonly found in non-polluted soils and roots associated with contaminated edible parts, raising the possibility of atmospheric contamination. Such a hypothesis is in agreement with values of magnetic susceptibility, since iron oxides and probably their associated metal(loid)s do not translocate from the roots toward the upper parts of the plants. (Bioaccessible) estimated dose intake ((B)EDI) and total (bioaccessible) target hazard quotient (Σ(B)THQ) were calculated to assess the health risk of consuming vegetables from this area. Pb and Sb were the major risk contributors. Taking the bioaccessible fractions into account, ΣBTHQ values were lower than ΣTHQ but were all still >1 for both males and females, leading to the conclusion that consuming these vegetables from this area is not risk-free.
Mostrar más [+] Menos [-]Inactivation of Microcystis aeruginosa by Electron Beam Irradiation
2014
Liu, Shuyu | Zhao, Yueping | Jiang, Wenjun | Wu, Minghong | Ma, Fang
Microcystis aeruginosa, the most common toxic cyanobacterial bloom, could cause severe environmental problem by producing and releasing lethal cyanobacterial toxins to water body. This study investigated the electron beam irradiation for the inactivation of M. aeruginosa. The treatment process was monitored via the measurement of chlorophyll a concentration, optical density, photosynthesis, and antioxidant enzymes. At low electron beam irradiation dose (1.0 kGy), its performance is not desirable. High dosage of electron beam irradiation (2.0–5.0 kGy) can dramatically decrease chlorophyll a concentration, optical density, and photosynthesis rate and affect activities of antioxidant enzymes. The transmission electron microscopy measurement indicates that electron beam irradiation treatment cause significant damages on integrity and morphology. Our results demonstrate that electron beam irradiation is a promising technique for quick and efficient inactivation of M. aeruginosa in aqueous solution.
Mostrar más [+] Menos [-]Monitoring Hg and Cd Contamination Using Red Swamp Crayfish (Procambarus clarkii): Implications for Wetland Food Chain Contamination
2014
Henriques, J. F. | Tavares, P. C. | Correia-dos-Santos, M. M. | Trancoso, M. A. | Santos-Reis, M. | Branquinho, C.
Environmental pollution is one of the most serious causes of degradation of Mediterranean wetlands. Mercury (Hg) and cadmium (Cd) are of particular concern due to biomagnification. Here, we used red swamp crayfish (Procambarus clarkii) to monitor the spatial and temporal patterns of these two metals in a Portuguese rice field system. We sampled the crayfish in three different sites and three different time periods in the Sado River Basin (Portugal). We measured temperature, pH, total dissolved solids and conductivity in the water. Hg and Cd were measured in the crayfish abdominal muscle tissue and exoskeleton. In muscle, a spatial pattern was found for the accumulation of Cd while for Hg, only a temporal pattern emerged. The spatial pattern for Cd seemed to reflect the mining history of the sites, whereas the temporal pattern for Hg seemed related to the flooding of rice fields. We suggest that this flooding process increases Hg bioavailability.
Mostrar más [+] Menos [-]Geochemistry of Tungsten and Arsenic in Aquifer Systems: A Comparative Study of Groundwaters from West Bengal, India, and Nevada, USA
2014
Mohajerin, T Jade | Neal, Andrew W. | Telfeyan, Katherine | Sasihharan, Sankar M. | Ford, Sophie | Yang, Ningfang | Chevis, Darren A. | Grimm, Deborah A. | Datta, Saugata | White, Christopher D. | Johannesson, Karen H.
Tungsten (W) concentrations were measured along with arsenic (As) in groundwaters from the Murshidabad district of West Bengal, India. Tungsten concentrations range from 0.8 to ~8 nmol kg⁻¹(0.15–1.5 μg kg⁻¹) in the circumneutral pH (average pH ~ 7.3) Murshidabad groundwaters, and attain concentrations as high as 14 nmol kg⁻¹(2.5 μg kg⁻¹) in local ponds (n = 2). Total dissolved As concentrations (AsT) range from 0.013 to 53.9 μmol kg⁻¹(<1 to 4,032 μg kg⁻¹), and As(III) predominates in Murshidabad groundwaters accounting for 70 %, on average, of As in solution. Tungsten concentrations in Murshidabad groundwaters are low compared to alkaline groundwaters (pH > 8) from the Carson Desert in Western Nevada, USA, where W concentrations are reported to reach as high as 4,036 nmol kg⁻¹(742 μg kg⁻¹). Although W is positively correlated with As in groundwaters from the Carson Desert, it is not correlated with AsTor As(III) in Murshidabad groundwaters, but does exhibit a weak relationship with As(V) in these groundwaters. Surface complexation modeling indicates that pH related adsorption/desorption can explain the geochemical behavior of W in Murshidabad groundwaters. However, the model does not predict the high As concentrations observed in Murshidabad groundwaters. The high As and low W concentrations measured in Murshidabad groundwaters indicate that either As and W originate from different sources or are mobilized by different biogeochemical processes within the Murshidabad aquifers. Mobilization of As in Murshidabad groundwaters is presumed to reflect reductive dissolution of Fe(III) oxides/oxyhydroxides and release of sorbed and/or coprecipitated As to the groundwaters. Multivariate statistical analysis of groundwater composition data indicate that W is associated with Mn and Cl⁻, which may point to a Mn oxide/oxyhydroxide, clay mineral, and/or apatite source for W in the Murshidabad sediments.
Mostrar más [+] Menos [-]Occurrence of Micro-pollutants in a Soil–Radish System Irrigated with Several Types of Treated Domestic Wastewater
2014
Petousi, I. | Fountoulakis, M. S. | Tzortzakis, N. | Dokianakis, S. | Stentiford, E. I. | Manios, T.
During this study, the effect of applying several types of treated domestic wastewater on the translocation and accumulation of organic and inorganic micropollutants in soil and radish plants (Raphanus sativus L.) was examined. Primary (PTW), secondary (STW) and tertiary (TTW) treated wastewater as well as tap water (TW) were used for the irrigation of radish plants for a period (transplantating and harvesting) of 67 days. Higher concentrations of polycyclic aromatic hydrocarbons (PAHs) were observed in soils irrigated with PTW. The concentration of PAHs in radish roots ranged between 107.6 ± 12.1 μg/kg for plants irrigated with TTW and 124.1 ± 17.7 μg/kg for plants irrigated with PTW. The root concentration factors (RCFs) expressed as the ratio of PAH concentration in the root mass (dry weight) to the residual concentration in the soil varied from 1.6 to 1.9 indicating a higher accumulation of PAHs in the edible part of radishes than soil. Heavy metals were not detected in the wastewaters utilised and, as a result, no accumulation was found in either the soil or plants in comparison with tap water. RCFs for heavy metals were calculated between 0.91 and 0.99, 0.49 and 0.66, 0.004 and 0.005 for Cu, Zn and Ni, respectively. The results showed that radishes have the ability to concentrate PAHs when they are present in the wastewater and this could have associated health risks.
Mostrar más [+] Menos [-]Roadway Deicer Effects on the Germination of Native Grasses and Forbs
2014
Dudley, Megan M. | Jacobi, William R. | Brown, Cynthia S.
Normal seed germination of native herbaceous species can be reduced by high concentrations of deicer products and their constituent salts. Chloride salts are commonly used during the winter months in temperate climates to remove ice and snow. Although these products greatly improve driving conditions, they can have detrimental effects on the vegetation growing along highways. The purpose of this laboratory study was to determine the impact of a magnesium-based deicer product and a sodium-based deicer product and the major salts they contain on the germination and viability of several species of grasses and forbs native to Colorado and planted in revegetation seedings there. Seeds were placed on blotter paper saturated with either a water control, one of three concentrations of each of the deicing solutions, or one of three concentrations of a pure NaCl or MgCl₂ solution. Increasing concentrations of salt ions generally resulted in delayed and reduced normal seed germination, especially the sodium- and magnesium-based deicer solutions. Germination for most species was lower when seeds were grown in deicer solution compared with germination percent of seeds grown in the pure salt solutions. Some species were more tolerant of one of the salts and deicers. Species with C4 photosynthetic pathway were more tolerant than C3 species of high concentrations of both deicer products. Those species which attained the highest germination percent under moderate or high solution concentrations included blue grama, buffalograss, little bluestem, mountain brome, and slender wheatgrass.
Mostrar más [+] Menos [-]Trends in Surface Water Chemistry in Acidified Areas in Europe and North America from 1990 to 2008
2014
Garmo, Øyvind A. | Skjelkvåle, Brit Lisa | de Wit, Heleen A. | Colombo, Luca | Curtis, Chris | Fölster, Jens | Hoffmann, Andreas | Hruška, Jakub | Høgåsen, Tore | Jeffries, Dean S. | Keller, W Bill | Krám, Pavel | Majer, Vladimír | Monteith, Don T. | Paterson, Andrew M. | Rogora, Michela | Rzychoń, Dorota | Steingruber, Sandra | Stoddard, John L. | Vuorenmaa, Jussi | Worsztynowicz, Adam
Acidification of lakes and rivers is still an environmental concern despite reduced emissions of acidifying compounds. We analysed trends in surface water chemistry of 173 acid-sensitive sites from 12 regions in Europe and North America. In 11 of 12 regions, non-marine sulphate (SO₄*) declined significantly between 1990 and 2008 (−15 to −59 %). In contrast, regional and temporal trends in nitrate were smaller and less uniform. In 11 of 12 regions, chemical recovery was demonstrated in the form of positive trends in pH and/or alkalinity and/or acid neutralising capacity (ANC). The positive trends in these indicators of chemical recovery were regionally and temporally less distinct than the decline in SO₄* and tended to flatten after 1999. From an ecological perspective, the chemical quality of surface waters in acid-sensitive areas in these regions has clearly improved as a consequence of emission abatement strategies, paving the way for some biological recovery.
Mostrar más [+] Menos [-]Relationships Between Heavy Metals Contamination in Shallow Marine Sediments with Industrial and Urban Development in Catalonia (Northwestern Mediterranean Sea)
2014
Pinedo, Susana | Jordana, Esther | Flagella, Maria Monia | Ballesteros, Enric
A total of 179 surface sediment samples from shallow waters have been collected in Catalonia (Northwestern Mediterranean) from 2002 to 2010 to analyze heavy metals (Al, Cd, Cu, Hg, Pb, V, and Zn) concentrations, organic matter content, and sediment size in order (i) to find baseline values, (ii) to investigate metal contamination trends, and (iii) to identify its spatial and temporal distribution. Highest metals concentrations were registered in the Barcelona metropolitan area and in the mouth of Besòs and Llobregat Rivers for Zn, Cu, Pb, and Cd. Mercury was also abundant in these areas but the highest record was found close to Tarragona. The concentrations agree with those reported in other studies performed in big river’s mouths and industrialized areas. The absence of large industrial activity and urbanization outside Barcelona and Tarragona explains the low metal contents found at the other sampling sites. Based on enrichment factor (EF), Pb was the most enriched metal. Results will provide a useful aid for sustainable marine management in Catalonia.
Mostrar más [+] Menos [-]Potential of Various Biosorbents for Zn(II) Removal
2014
Kőnig-Péter, Anikó | Csudai, Csaba | Felinger, Attila | Kilár, Ferenc | Pernyeszi, Tímea
The adsorption capacities of six biosorbents (Pseudomonas aeruginosa, Pseudomonas fluorescens, Escherichia coli, Chlorella vulgaris, and Spirulina platensis) for Zn(II) ions under batch condition have been studied. The optimum pH range was found to be 5.0−6.0. The amount of adsorbed Zn(II) ions were between 18 and 128 mg/g. Characterization of biosorption equilibrium was evaluated with Langmuir and Dubinin-Radushkevich model using non-linear regression. The adsorption capacities of Ca-alginate, chitosan, and immobilized Spirulina platensis-maxima cells were also determined in packed-bed column in continuous system. The results show, free Spirulina cells have the highest adsorption capacity for Zn(II) ions (128 mg/g). The chitosan-Spirulina system has slightly decreased adsorption capacity 98 mg/g per dry weight content. Thomas and Yoon-Nelson models were fitted for the evaluation of experimental data.
Mostrar más [+] Menos [-]Potential for phytoextraction of copper by Sinapis alba and Festuca rubra cv. Merlin grown hydroponically and in vineyard soils
2014
Malagoli, Mario | Rossignolo, Virginia | Salvalaggio, Nico | Schiavon, Michela
The extensive use of copper-bearing fungicides in vineyards is responsible for the accumulation of copper (Cu) in soils. Grass species able to accumulate Cu could be cultivated in the vineyard inter-rows for copper phytoextraction. In this study, the capacity of Festuca rubra cv Merlin and Sinapis alba to tolerate and accumulate copper (Cu) was first investigated in a hydroponic system without the interference of soil chemical–physical properties. After the amendment of Cu (5 or 10 mg Cu l⁻¹) to nutrient solution, shoot Cu concentration in F. rubra increased up to 108.63 mg Cu kg⁻¹DW, more than three times higher than in S. alba (31.56 mg Cu kg⁻¹DW). The relationship between Cu concentration in plants and external Cu was dose-dependent and species specific. Results obtained from the hydroponic experiment were confirmed by growing plants in pots containing soil collected from six Italian vineyards. The content of soil organic matter was crucial to enhance Cu tolerance and accumulation in the shoot tissues of both plant species. Although S. alba produced more biomass than F. rubra in most soils, F. rubra accumulated significantly more Cu (up to threefold to fourfold) in the shoots. Given these results, we recommended that F. rubra cv Merlin could be cultivated in the vineyard rows to reduce excess Cu in vineyard soils.
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