خيارات البحث
النتائج 1921 - 1930 من 3,208
Toxic metals in topsoil under different land uses from Xiandao District, middle China: distribution, relationship with soil characteristics, and health risk assessment النص الكامل
2015
Li, Fei | Huang, Jinhui | Zeng, Guangming | Liu, Wenchu | Huang, Xiaolong | Huang, Bin | Ku, Yenlin | Shi, Lixiu | He, Xiaoxiao | He, Yan
To explore mutual relationship among soil characteristics (soil organic matter, soil texture, cation exchange capacity, and pH), land uses, toxic metal (As, Hg, Mn, and Ni) distributions and induced health risk, 156 topsoil samples (0–20 cm) were collected from farm land, forest land and construction land in a grid pattern throughout Xiandao District. Compared with Hunan soil background values, the elevated concentrations of As, Hg and Ni were found to different extent. Pearson correlation matrix suggested As-silt, Mn-Ni, CEC-Mn, CEC-Ni, and CEC-pH had significantly positive correlation, and significantly negative correlation existed in SOM-pH, CEC-clay, SOM-Ni, and SOM-pH. Results based on the soil texture analysis, analysis of variance, and Tukey test indicated the concentrations of As and Ni were higher in relatively fine textures, and the mean contents of As, Mn, Ni, pH, and SOM in construction land, construction land, construction land, forest land, and construction land, respectively, were with the significant difference from that in the other two land uses. For non-carcinogenic effects, Hazard Indexes (HIs) of Ni, Hg, Mn, and As decreased in the order of As > Hg > Mn > Ni to both children and adults. Risk contributions of each exposure pathway decreased in the order of ingestion > dermal contact > inhalation of resuspended particles for HIAₛ, HIMₙ, and HINᵢ. The inhalation of vapors was the highest contributor for HIHg, followed by ingestion, dermal contact, and inhalation of resuspended particles. As and Hg were regarded as the priority pollutants. The hierarchical risk areas were identified after comprehensive consideration of local residential population density distribution, and the different risk management measures were finally suggested for the different priority areas.
اظهر المزيد [+] اقل [-]Changes of benthic bacteria and meiofauna assemblages during bio-treatments of anthracene-contaminated sediments from Bizerta lagoon (Tunisia) النص الكامل
2015
Ben Said, Olfa | Louati, Hela | Soltani, Amel | Preud’homme, Hugues | Cravo-Laureau, Cristiana | Got, Patrice | Pringault, Olivier | Aissa, Patricia | Duran, Robert
Sediments from Bizerta lagoon were used in an experimental microcosm setup involving three scenarios for the bioremediation of anthracene-polluted sediments, namely bioaugmentation, biostimulation, and a combination of both bioaugmentation and biostimulation. In order to investigate the effect of the biotreatments on the benthic biosphere, 16S rRNA gene-based T-RFLP bacterial community structure and the abundance and diversity of the meiofauna were determined throughout the experiment period. Addition of fresh anthracene drastically reduced the benthic bacterial and meiofaunal abundances. The treatment combining biostimulation and bioaugmentation was most efficient in eliminating anthracene, resulting in a less toxic sedimentary environment, which restored meiofaunal abundance and diversity. Furthermore, canonical correspondence analysis showed that the biostimulation treatment promoted a bacterial community favorable to the development of nematodes while the treatment combining biostimulation and bioaugmentation resulted in a bacterial community that advantaged the development of the other meiofauna taxa (copepods, oligochaetes, polychaetes, and other) restoring thus the meiofaunal structure. The results highlight the importance to take into account the bacteria/meiofauna interactions during the implementation of bioremediation treatment.
اظهر المزيد [+] اقل [-]Concentrations, bioaccumulation, and human health risk assessment of organochlorine pesticides and heavy metals in edible fish from Wuhan, China النص الكامل
2015
Cui, Lili | Ge, Jing | Zhu, Yindi | Yang, Yuyi | Wang, Jun
The objective of this study was to determine concentration and bioaccumulation of organochlorine pesticides and heavy metals in edible fish from Wuhan, China, in order to assess health risk to the human via fish consumption. Two edible fish species (Aristichthys nobilis and Hypophthalmichthys molitrix) were collected and analyzed for 11 organochlorine pesticides (OCPs) and eight heavy metals (HMs). Concentrations of ∑HCHs, ∑DDTs, and ∑OCPs in fish samples were in the range of 0.37–111.20, not detected (nd)–123.61, and 2.04–189.04 ng g⁻¹ (wet weight), respectively. Bioaccumulation factors (BAFs) of OCPs in bighead carp (A. nobilis) were higher than those in silver carp (H. molitrix). Concentrations of ∑HMs in bighead carp and silver carp were 352.48 and 345.20 mg kg⁻¹ (dw), respectively. Daily exposure of OCPs and HMs for consumers was estimated by comparing estimated daily intake (EDI) with different criteria. The results revealed that the EDIs in our study were all lower than those criteria. Target hazard quotient (THQ) and risk ratio (R) were used to evaluate non-carcinogenic and carcinogenic risks, respectively. As regard to non-carcinogenic effects of the contaminants, hazard quotients (THQ) of OCPs and HMs were both lower than 1.0, implying negligible non-carcinogenic risk via fish consumption in study area. Nevertheless, in view of carcinogenic effects of the contaminants, the total value of risk ratio (R) of OCPs was lower than the threshold of tolerable risk while the total value of risk ratio (R) of HMs was higher than the threshold of tolerable risk due to the high carcinogenic risk ratios of As and Cr, indicating high carcinogenic risks via fish consumption. The results demonstrated that HMs in edible fish from Wuhan, China, especially As and Cr required more attention than OCPs.
اظهر المزيد [+] اقل [-]Numerical study of a buoyant plume from a multi-flue stack into a variable temperature gradient atmosphere النص الكامل
2015
Velamati, Ratna Kishore | Vivek, M. | Goutham, K. | Sreekanth, G. R. | Dharmarajan, Santosh | Goel, Mukesh
Air pollution is one of the major global hazards and industries have been one of its major contributors. This paper primarily focuses on analyzing the dispersion characteristics of buoyant plumes of the pollutant released from a multi-flue vertical stack into a variable temperature gradient atmosphere (α) in a constant-velocity cross wind using two stack configurations—inline and parallel. The study is conducted for different Froude numbers, Fr = 12.64, 9.55, and 8.27. The atmospheric temperature gradients considered for the study are 0, +1, +1.5, and +2 K/100 m. The numerical study is done using the commercial computational fluid dynamics (CFD) code FLUENT. The effects of stack configuration, α, and Fr on the plume characteristics are presented. It is observed that the plume rises higher and disperses over a larger area with the inline configuration due to better mixing and shielding effect. With higher α, it is seen that the plume rises initially and then descends due to variation of the buoyant force. The plume rise initially is strongly influenced by the momentum of the jet, and as it moves downstream, it is influenced by the cooling rate of the plume. Furthermore, the plume rises higher and disperses over a larger area with a decrease in Fr.
اظهر المزيد [+] اقل [-]Stable sulfur isotope ratios and water-soluble inorganic compositions of PM10 in Yichang City, central China النص الكامل
2015
Yang, Zhou | Li, Xiao-Dong | Deng, Jie | Wang, Haiyun
Chemical and sulfate-sulfur isotopic compositions of water-soluble inorganic ions were analyzed for aerosol sample particulate matter with aerodynamic diameter ≤10 μm (PM₁₀) collected during 17–28 December 2012 at Yichang City, Hubei Province, central China. Most water-soluble inorganic ions, except for NO₃ ⁻ and NH₄ ⁺, showed slightly higher concentration in daytime than in nighttime, and the major detected ions followed the order of SO₄ ²⁻ > NO₃ ⁻ > Ca²⁺ > Na⁺ > NH₄ ⁺ > Cl⁻ in daytime and nighttime, of which SO₄ ²⁻ is the most abundant ionic component that accounted for about 49.1 and 49.3 % of the total mass of analyzed ions in daytime and nighttime, respectively. According to the correlation coefficients among the mass concentrations of water-soluble inorganic ions, there may mainly exist in forms of (NH₄)₂SO₄ and NH₄NO₃ in daytime and NH₄NO₃ in nighttime. The δ³⁴S values of sulfate ranged from +2.82 to +4.63 ‰ (average +3.97 ‰) in daytime and from +2.90 to +5.39 ‰ (average +4.08 ‰) in nighttime, indicating that the source of sulfate in PM₁₀ was mainly derived from coal burning (δ³⁴S, +3.68 ‰) in Yichang City. The [NO₃ ⁻]/[SO₄ ²⁻] mass ratio varied between 0.2 and 0.6 with an average of 0.4 in daytime and 0.1 to 0.8 with an average of 0.4 in nighttime, which implying that the stationary source emissions would be more important than the vehicle emissions in the studied area. As a whole, the mixture of coal burning, vehicle exhaust, and resuspended road dust would be responsible for the sources of PM₁₀ in Yichang City during wintertime.
اظهر المزيد [+] اقل [-]Phytoremediation of cadmium improved with the high production of endogenous phenolics and free proline contents in Parthenium hysterophorus plant treated exogenously with plant growth regulator and chelating agent النص الكامل
2015
Ali, Nasir | Hadi, Fazal
Pot experiments were conducted to evaluate the effects of gibberellic acid (GA₃) and ethylenediaminetetraacetic acid (EDTA) on growth parameters, cadmium (Cd) phytoextraction, total phenolics, free proline and chlorophyll content of Parthenium hysterophorus plant grown in Cd-contaminated (100 mg/kg) soil. GA₃ was applied as foliar spray (10⁻², 10⁻⁴ and 10⁻⁶ M) while EDTA (40 mg/kg soil) was added to soil as single and in split doses. Results showed decrease in growth parameters due to Cd stress but P. hysterophorus plant demonstrated Cd hyperaccumulator potential based on bioconcentration factor (BCF). Lower concentration of GA₃ (10⁻⁶ M) showed highest significant increase in the growth parameters while Cd concentration, accumulation (1.97 ± 0.11 mg/DBM) and bioconcentration (9.75 ± 0.34) was significantly higher in the treatment T11 (GA₃ 10⁻² + split doses of EDTA). Cadmium significantly increased the root free proline while total phenolic concentration was significantly high in all parts of the plant. Chlorophyll contents were significantly reduced by Cd. GA₃ showed significant increase in phenolic and chlorophyll contents in plant. Cadmium accumulation in plant tissues showed positive correlation with free proline (R ² = 0.527, R ² = 0.630) and total phenolics (R ² = 0.554, R ² = 0.723) in roots and leaves, respectively. Cd contents negatively correlated with biomass, chlorophyll and total water contents. Proline and phenolic contents showed positive correlation with dry biomass of plant. These findings suggest further investigation to study the role of endogenous phenolics and proline in heavy metal phytoremediation.
اظهر المزيد [+] اقل [-]Andra Environmental Specimen Bank: archiving the environmental chemical quality for long-term monitoring النص الكامل
2015
Leclerc, Elisabeth | d’Arbaumont, Maëlle | Verron, Jean-Patrick | Goldstein, Céline | Cesar, Frédérique | Dewonck, Sarah
Andra Environmental Specimen Bank (ESB) was established in 2010 as a part of the Perennial Observatory of the Environment (OPE), ongoing Long-Term Environmental Research Monitoring and Testing System located next to the Underground Research Laboratory (URL) at Bure, Meuse/Haute-Marne, France. The URL is used to study the deep geological disposal of high and intermediate level radioactive waste. Andra ESB is designed to archive during at least 100 years samples collected to define the initial state of environmental quality of the local area before the construction of industrial facilities and to ensure the traceability of long-term series of samples collected by the OPE (http://www.andra.fr/ope), using safe long-term conservation practices. Samples archived in the bank include some local food chain products (milk, cheese, honey, cereals, grass, cherry plum…) and specimen usually archived internationally to monitor the environmental quality (soil, sediment, water, fish, tree leaves, wild life, etc.). Regarding the different samples and analytical issues, three conservation modalities and facilities were designed: dry conservation under controlled temperature and humidity, cryopreservation in liquid nitrogen (LN2) vapor phase freezers (−150 °C) and in deep-freezing at −80 °C for temporary storage and raw samples before preparation. Andra ESB is equipped with a sample preparation clean room, certified ISO Class 5, dedicated to cryopreservation. This paper describes this first French experiment of long-term chemical quality monitoring and samples cryopreservation of different ecosystems and environmental compartments.
اظهر المزيد [+] اقل [-]Comparing the performance of geostatistical models with additional information from covariates for sewage plume characterization النص الكامل
2015
Del Monego, Maurici | Ribeiro, Paulo Justiniano Jr | Ramos, Patricia
In this work, kriging with covariates is used to model and map the spatial distribution of salinity measurements gathered by an autonomous underwater vehicle in a sea outfall monitoring campaign aiming to distinguish the effluent plume from the receiving waters and characterize its spatial variability in the vicinity of the discharge. Four different geostatistical linear models for salinity were assumed, where the distance to diffuser, the west-east positioning, and the south-north positioning were used as covariates. Sample variograms were fitted by the Matèrn models using weighted least squares and maximum likelihood estimation methods as a way to detect eventual discrepancies. Typically, the maximum likelihood method estimated very low ranges which have limited the kriging process. So, at least for these data sets, weighted least squares showed to be the most appropriate estimation method for variogram fitting. The kriged maps show clearly the spatial variation of salinity, and it is possible to identify the effluent plume in the area studied. The results obtained show some guidelines for sewage monitoring if a geostatistical analysis of the data is in mind. It is important to treat properly the existence of anomalous values and to adopt a sampling strategy that includes transects parallel and perpendicular to the effluent dispersion.
اظهر المزيد [+] اقل [-]Sorption and desorption of Cr(VI) ions from water by biochars in different environmental conditions النص الكامل
2015
Tytłak, Aleksandra | Oleszczuk, Patryk | Dobrowolski, Ryszard
In the present research, the potential of two biochars produced by the thermal decomposition of wheat straw (BCS) and wicker (BCW) for Cr(VI) ions removing from wastewater was investigated. The pH and the presence of chlorides and nitrates were also investigated. The Freundlich and Langmuir models were applied for the characterization of adsorption isotherms. The Langmuir model has better fitting of adsorption isotherms than the Freundlich model. The sorption process can be described by the pseudo second-order equation. The optimal adsorption capacities were obtained at pH 2 and were 24.6 and 23.6 mg/g for BCS and BCW, respectively. X-ray photoelectron spectroscopy (XPS) studies confirmed that Cr(III) ions were the most abundant chromium species on the biochars’ surface. The results indicated that the sorption mechanism of Cr(VI) on biochar involves anionic and cationic adsorption combined with Cr(VI) species reduction.
اظهر المزيد [+] اقل [-]Effect of inorganic amendments for in situ stabilization of cadmium in contaminated soils and its phyto-availability to wheat and rice under rotation النص الكامل
2015
Rehman, Muhammad Zia-ur | Rizwan, Muhammad | Ghafoor, Abdul | Naeem, Asif | Ali, Shafaqat | Ṣābir, Muḥammad | Qayyum, Muhammad Farooq
Cadmium (Cd) toxicity is a widespread problem in crops grown on contaminated soils, and little information is available on the role of inorganic amendments in Cd immobilization, uptake, and tolerance in crops especially under filed conditions. The effect of three amendments, monoammonium phosphate (MAP), gypsum, and elemental sulfur (S), on Cd immobilization in soil and uptake in wheat and rice plants, under rotation, were investigated under field conditions receiving raw city effluent since >20 years and contaminated with Cd. Three levels of each treatment, 0.2, 0.4, and 0.8 % by weight, were applied at the start of the experiment, and wheat was sown in the field. After wheat harvesting, rice was sown in the same field without application of amendments. Both crops were harvested at physiological maturity, and data regarding grain yield, straw biomass, Cd concentrations, and uptake in grain and straw, and bioavailable Cd in soil and soil pH were recorded. Both MAP and gypsum application increased grain yield and biomass of wheat and rice, while S application did not increase the yield of both crops. MAP and gypsum amendments decreased gain and straw Cd concentrations and uptake in both crops, while S application increased Cd concentrations in these parts which were correlated with soil bioavailable Cd. We conclude that MAP and gypsum amendments could be used to decrease Cd uptake by plants receiving raw city effluents, and gypsum might be a better amendment for in situ immobilization of Cd due to its low cost and frequent availability.
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