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Résultats 2151-2160 de 3,197
Stereoselective degradation of flutriafol and tebuconazole in grape
2015
Zhang, Qing | Hua, Xiude | Yang, Yu | Yin, Wei | Tian, Mingming | Shi, Haiyan | Wang, Minghua
The stereoselective dissipation of flutriafol and tebuconazole in grape had been studied. A simple and sensitive method for determination of flutriafol and tebuconazole enantiomers in grape was developed by high-performance liquid chromatography on a cellulose tris(3-chloro-4-methylphenylcarbamate) column. The limits of quantification for flutriafol and tebuconazole in grape were 0.033 and 0.043 mg kg⁻¹, respectively. The dissipations of flutriafol and tebuconazole stereoisomers in grape followed first-order kinetics (R² > 0.93). The stereoisomers of flutriafol and tebuconazole were enantioselectively degraded in grape, and tebuconazole was more enantioselective than flutriafol. The half-life of (−)-tebuconazole was 5.2 days and shorter than (+)-tebuconazole with half-life of 6.4 days. The (−)-flutriafol was also preferentially degraded in grape, the half-lives of which were 6.59 and 6.98 days for (−) and (+)-flutriafol, respectively. The enantiomeric ratio value of the two fungicides was nearly 1.0 at the 1st day and increased to 1.143 for flutriafol and 2.015 for tebuconazole at the 28th day. The stereoselective dissipations could provide a reference to fully evaluate the risks of two important chiral triazole fungicides.
Afficher plus [+] Moins [-]Ammonium-nitrogen-contaminated groundwater remediation by a sequential three-zone permeable reactive barrier (multibarrier) with oxygen-releasing compound (ORC)/clinoptilolite/spongy iron: column studies
2015
Huang, Guoxin | Liu, Fei | Yang, Yingzhao | Kong, Xiangke | Li, Shengpin | Zhang, Ying | Cao, Dejun
A novel sequential permeable reactive barrier (multibarrier), composed of oxygen-releasing compound (ORC)/clinoptilolite/spongy iron zones in series, was proposed for ammonium-nitrogen-contaminated groundwater remediation. Column experiments were performed to: (1) evaluate the overall NH₄⁺–N removal performance of the proposed multibarrier, (2) investigate nitrogen transformation in the three zones, (3) determine the reaction front progress, and (4) explore cleanup mechanisms for inorganic nitrogens. The results showed that NH₄⁺–N percent removal by the multibarrier increased up to 90.43 % after 21 pore volumes (PVs) at the influent dissolved oxygen of 0.68∼2.45 mg/L and pH of 6.76∼7.42. NH₄⁺–N of 4.06∼10.49 mg/L was depleted and NO ₓ ⁻–N (i.e., NO₃⁻–N + NO₂⁻–N) of 4.26∼9.63 mg/L was formed before 98 PVs in the ORC zone. NH₄⁺–N of ≤4.76 mg/L was eliminated in the clinoptilolite zone. NO ₓ ⁻–N of 10.44∼12.80 mg/L was lost before 21 PVs in the spongy iron zone. The clinoptilolite zone length should be reduced to 30 cm. Microbial nitrification played a dominant role in NH₄⁺–N removal in the ORC zone. Ion exchange was majorly responsible for NH₄⁺–N elimination in the clinoptilolite zone. Chemical reduction and hydrogenotrophic denitrification both contributed to NO ₓ ⁻–N transformation, but the chemical reduction capacity decreased after 21 PVs in the spongy iron.
Afficher plus [+] Moins [-]Effect-based assessment of persistent organic pollutant and pesticide dumpsite using mammalian CALUX reporter cell lines
2015
Pieterse, B. | Rijk, I. J. C. | Simon, E. | van Vugt-Lussenburg, B. M. A. | Fokke, B. F. H. | van der Wijk, M. | Besselink, H. | Weber, R. | van der Burg, B.
A combined chemical and biological analysis of samples from a major obsolete pesticide and persistent organic pollutant (POP) dumpsite in Northern Tajikistan was carried out. The chemical analytical screening focused on a range of prioritized compounds and compounds known to be present locally. Since chemical analytics does not allow measurements of hazards in complex mixtures, we tested the use of a novel effect-based approach using a panel of quantitative high-throughput CALUX reporter assays measuring distinct biological effects relevant in hazard assessment. Assays were included for assessing effects related to estrogen, androgen, and progestin signaling, aryl hydrocarbon receptor-mediated signaling, AP1 signaling, genotoxicity, oxidative stress, chemical hypoxia, and ER stress. With this panel of assays, we first quantified the biological activities of the individual chemicals measured in chemical analytics. Next, we calculated the expected sum activity by these chemicals in the samples of the pesticide dump site and compared the results with the measured CALUX bioactivity of the total extracts of these samples. The results showed that particularly endocrine disruption-related effects were common among the samples. This was consistent with the toxicological profiles of the individual chemicals that dominated these samples. However, large discrepancies between chemical and biological analysis were found in a sample from a burn place present in this site, with biological activities that could not be explained by chemical analysis. This is likely to be caused by toxic combustion products or by spills of compounds that were not targeted in the chemical analysis.
Afficher plus [+] Moins [-]Aquatic oil spill cleanup using natural sorbents
2015
Paulauskienė, Tatjana | Jucikė, Indrė
One of the most popular transportation methods of crude oil is water transport, leading to potential spills of these pollutants in the seas and oceans and water areas of ports, during their extraction, transportation, transhipment and use. The growth of the Lithuanian economy and the expansion of competitiveness were hardly imagined without the development of the Klaipeda seaport. However, the intensity of shipping and the increase in cargo loading volumes at specialised terminals are associated with a higher risk of environmental pollution. To achieve a sustainable development of the seaport, it is necessary not only to ensure the prevention of potential water pollution but also, if necessary, to use environmentally friendly technology for pollution management. The work analyses the possibilities related to the collection of oil products from the water surface using natural sorbents (peat, wool, moss and straw) and their composites.The research of absorbed amount of crude oil and diesel fuel spilled on the water surface, while using sorbents and their composites, determined that sorbents’ composite straw-peat (composition percentage of straw-peat 25–75 %) absorbs the major amount of both crude oil (60 % of the spilled volume) and diesel fuel (69 % of the spilled volume) comparing to single sorbents and sorbents’ composite straw-peat (composition percentage of straw-peat 50–50 %).
Afficher plus [+] Moins [-]Effects of urbanization on gaseous and particulate polycyclic aromatic hydrocarbons and polychlorinated biphenyls in a coastal city, China: levels, sources, and health risks
2015
Hong, Youwei | Chen, Jinsheng | Zhang, Fuwang | Zhang, Han | Xu, Lingling | Yin, Liqian | Chen, Yanting
Gas/particle distributions of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in Xiamen from May 2009 to March 2010 to evaluate the impacts of urbanization on the fate of persistent organic pollutants (POPs) in the atmospheric environment. In a newly developing area (NDA), the concentrations of 16 PAHs (gas + particle) were significantly higher than that a historically urbanized area (HUA) (p value <0.05), while the trend of 28 PCBs was reversed. Diagnostic ratios and principle component analysis (PCA) implied that atmospheric PAHs in the NDA were mainly derived from petrogenic combustion, including mixed sources of vehicle emissions, biomass burning and oil combustion, while pyrogenic combustion (e.g., traffic and coal combustion) was considered the major source of PAHs in the HUA. Atmospheric PCBs in both HUA and NDA were dominated by TriCBs and PeCBs related to the use of commercial mixtures (Aroclors 1242 and 1254). Based on the toxicological equivalent factor (TEF) approach, total benzo[a]pyrene equivalent values in the HUA and NDA were 1.12 and 2.02 ng m⁻³, respectively, exceeding the standard threshold values (1.0 ng m⁻³) of China and WHO. Average daily intake of dioxin-like compounds was 0.2 pg kg⁻¹ day⁻¹ in the HUA, which are below the WHO tolerable daily intake level. The results showed that the contribution to the toxic equivalency (TEQ) was dominated by PCB169, PCB105, and PCB81.
Afficher plus [+] Moins [-]Effect of inorganic amendments for in situ stabilization of cadmium in contaminated soils and its phyto-availability to wheat and rice under rotation
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.
Afficher plus [+] Moins [-]Stable sulfur isotope ratios and water-soluble inorganic compositions of PM10 in Yichang City, central China
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.
Afficher plus [+] Moins [-]Sludge quality after 10–20 years of treatment in reed bed systems
2015
Nielsen, Steen | Bruun, Esben Wilson
The effect on the environment of the operation of sludge treatment in reed beds (STRB) system is seen as quite limited compared to traditional sludge treatment systems such as mechanical dewatering, drying and incineration with their accompanying use of chemicals and energy consumption. There are several STRB systems in Denmark receiving sludge from urban wastewater treatment plants. Stabilization and mineralization of the sludge in the STRB systems occur during a period between 10 and 20 years, where after the basins are emptied and the sludge residue typically is spread on agricultural land. In the present study, the sludge residue quality after treatment periods of 10–20 years from four Danish STRBs is presented. After reduction, dewatering and mineralization of the feed sludge (dry solid content of 0.5–3 %) in the STRB systems, the sludge residue achieved up to 26 % dry solid, depending on the sludge quality and dimensioning of the STRB system. The concentration of heavy metals and hazardous organic compounds in the sludge residue that are listed in the Danish and EU legislation for farmland application of sludge was below the limit values. The nitrogen and phosphorus concentrations as an average in the sludge residue were 28 and 36 g/kg dry solid (DS), respectively. In addition, mineralization on average across the four STRB systems removed up to 27 % of the organic solids in the sludge. The investigation showed that the sludge residue qualities of the four STRBs after a full treatment period all complied with the Danish and European Union legal limits for agricultural land disposal.
Afficher plus [+] Moins [-]Levels, spatial distribution, and exposure risks of decabromodiphenylethane in soils of North China
2015
Lin, Yan | Ma, Jin | Qiu, Xinghua | Zhao, Yifan | Zhu, Tong
Eighty-seven soil samples collected from North China were analyzed for decabromodiphenyl ethane (DBDPE). The concentrations of DBDPE ranged from undetectable to 1612 ng/g, with the highest concentration present in Shandong. Additionally, the mean concentration of DBDPE in Shandong was found to be onefold higher than those found in Hebei and Shanxi, likely due to DBDPE production in Shandong. Relatively high concentrations of DBDPE in soils were also present in the south of Tianjin, where e-waste recycling may provide a source in this region. The fractions of DBDPE [DBDPE/(DBDPE + BDE209)] were lower than 0.5 in most soil samples, in agreement with the fact that deca-BDE is currently the main additive in brominated flame retardants (BFR) used in China. An obvious decreasing trend in DBDPE concentrations from east to west in North China was noted, with relatively higher DBDPE concentrations present in Shandong. A soil ingestion exposure assessment showed that for most sites, soil ingestion EDI was slightly lower than inhalation EDI; exceptions were found in several polluted sites, where soil ingestion was a more significant exposure route.
Afficher plus [+] Moins [-]Uptake, effects, and regeneration of barley plants exposed to gold nanoparticles
2015
Feichtmeier, Nadine S. | Walther, Paul | Leopold, Kerstin
Within the last years, nanogold has become more and more important in nanotechnology, for example, as catalyst or in medical applications. Its rising production, application, and disposal inevitably lead to an increased emission of gold nanoparticles (Au-NPs) in the environment. However, only little is known about the uptake and effects of Au-NPs on biota. The objective of this study was to investigate the reversibility and effects of citrate-coated Au-NP uptake into the model organism barley (Hordeum vulgare L.). For this purpose, barley seeds were cultivated in Au-NP-containing nutrient solution for 2 weeks before the seedlings were transferred into Au-NP-free media and grown for another 3 weeks. Stability of Au-NPs in the cultivation media was investigated over the 2-week exposure time. Gold content in the leaves and roots of the plants was measured after 2 weeks of exposure and after 7, 14, and 21 days of regeneration by means of total reflection X-ray fluorescence (TXRF) analysis after microwave-assisted digestion. Moreover, Au-NPs within plant material were localized by transmission electron microscopy (TEM) of ultrathin cross sections. The obtained results reveal that Au-NPs accumulate in the plant roots. Concentration-dependent effects on the uptake of macronutrients and micronutrients, as well as on biomass production of exposed plants, in particular, on root growth were observed. Even though exposed barley plants were able to regenerate to a certain extent, their root growth was permanently decreased.
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