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Résultats 231-240 de 1,540
Physiological and molecular responses of the earthworm (Eisenia fetida) to soil chlortetracycline contamination
2012
Lin, Dasong | Zhou, Qixing | Xu, Yingming | Chen, Chun | Li, Ye
This study aims to evaluate toxic effects of exposure to chlortetracycline (CTC) in soil on reproductive endpoints (juvenile counts and cocoon counts), biochemical responses, and genotoxic potentials of the earthworm Eisenia fetida. Results showed that juvenile counts and cocoon counts of the tested earthworms were reduced after exposure to CTC. The effective concentrations (EC₅₀ values) for juvenile and cocoon counts were 96.1 and 120.3 mg/kg, respectively. Treatment of earthworms with CTC significantly changed the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST). An increase in malondialdehyde (MDA) indicated that CTC could cause cellular lipid peroxidation in the tested earthworms. The percentage of DNA in the tail of single-cell gel electrophoresis of coelomocytes as an indication of DNA damage increased after treatment with different doses of CTC, and a dose-dependent DNA damage of coelomocytes was found. In conclusion, CTC induces physiological responses and genotoxicity on earthworms.
Afficher plus [+] Moins [-]Enrichment behavior and transport mechanism of soil-bound PAHs during rainfall-runoff events
2012
Zheng, Yi | Luo, Xiaolin | Zhang, Wei | Wu, Bin | Han, Feng | Lin, Zhongrong | Wang, Xuejun
Polycyclic Aromatic Hydrocarbons (PAHs) transported by surface runoff result in nonpoint source pollution and jeopardize aquatic ecosystems. The transport mechanism of PAHs during rainfall-runoff events has been rarely studied regarding pervious areas. An experimental system was setup to simulate the runoff pollution process on PAHs-contaminated soil. The enrichment behavior of soil-bound PAHs was investigated. The results show that soil organic matters (SOM), rather than clay particles, seem to be the main carrier of PAHs. The enrichment is highly conditioned on runoff and erosion processes, and its magnitude varies among PAH compounds. It is not feasible to build a simple and universal relationship between enrichment ratio and sediment discharge following the traditional enrichment theory. To estimate the flux of PAHs from pervious areas, soil erosion process has to be clearly understood, and both organic carbon content and composition of SOM should be factored into the calculation.
Afficher plus [+] Moins [-]Phytochelatins play a key role in arsenic accumulation and tolerance in the aquatic macrophyte Wolffia globosa
2012
Zhang, Xin | Uroic, M Kalle | Xie, Wan-Ying | Zhu, Yong-Guan | Chen, Bao-Dong | McGrath, Steve P. | Feldmann, Jörg | Zhao, Fang-Jie
The rootless duckweed Wolffia globosa can accumulate and tolerate relatively large amounts of arsenic (As); however, the underlying mechanisms were unknown. W. globosa was exposed to different concentrations of arsenate with or without l-buthionine sulphoximine (BSO), a specific inhibitor of γ-glutamylcysteine synthetase. Free thiol compounds and As(III)–thiol complexes were identified and quantified using HPLC – high resolution ICP-MS – accurate mass ESI-MS. Without BSO, 74% of the As accumulated in the duckweed was complexed with phytochelatins (PCs), with As(III)–PC₄ and As(III)–PC₃ being the main species. BSO was taken up by the duckweed and partly deaminated. The BSO treatment completely suppressed the synthesis of PCs and the formation of As(III)–PC complexes, and also inhibited the reduction of arsenate to arsenite. BSO markedly decreased both As accumulation and As tolerance in W. globosa. The results demonstrate an important role of PCs in detoxifying As and enabling As accumulation in W. globosa.
Afficher plus [+] Moins [-]A review of multiple stressor studies that include ionising radiation
2012
Studies were reviewed that investigated the combined effects of ionising radiation and other stressors on non-human biota. The aim was to determine the state of research in this area of science, and determine if a review of the literature might permit a gross generalization as to whether the combined effects of multi-stressors and radiation are fundamentally additive, synergistic or antagonistic. A multiple stressor database was established for different organism groups. Information was collected on species, stressors applied and effects evaluated. Studies were mostly laboratory based and investigated two-component mixtures. Interactions declared positive occurred in 58% of the studies, while 26% found negative interactions. Interactions were dependent on dose/concentration, on organism's life stage and exposure time and differed among endpoints. Except for one study, none of the studies predicted combined effects following Concentration Addition or Independent Action, and hence, no justified conclusions can be made about synergism or antagonism.
Afficher plus [+] Moins [-]Assessment of N and P status at the landscape scale using environmental models and measurements
2012
We assessed the compliance of a Dutch landscape, dominated by dairy farming, with environmental quality standards using a combination of model calculations and measurements. The total ammonia emission of 2.4 kton NH₃ yr⁻¹ does not exceed the environmental quality standard (2.6 kton NH₃ yr⁻¹). Nevertheless, the total N deposition (on average 24.4 kg N ha⁻¹ yr⁻¹) is such that critical N loads are exceeded at 53% of the nature areas. The deposited N mainly results from non-agricultural sources and agricultural sources outside the area (72%). The calculated average NO₃ ⁻ concentration in the upper groundwater does not exceed the 50 mg l⁻¹ threshold. Calculated annual average N-total and P-total concentrations in discharge water are relatively high but these cannot be directly compared with thresholds for surface water. The results suggest that compliance monitoring at the landscape scale needs to include source indicators and cannot be based on state indicators alone.
Afficher plus [+] Moins [-]Inflammatory effects on human lung epithelial cells after exposure to diesel exhaust micron sub particles (PM₁.₀) and pollen allergens
2012
Asthma is currently defined as a chronic inflammatory disease of the airway. Several evidence indicate that vehicle emissions in cities is correlated with the allergic respiratory diseases. In the present study, we evaluated in the A549 cells the production and release of IL-4, IL-5 and IL-13 after treatment with sub-micron PM₁.₀ particles (PM₁.₀), Parietaria officinalis (ALL), and PM₁.₀ + ALL together. Our data demonstrated that PM₁.₀ + ALL together exhibited the greatest capacity to induce A549 cells to enhance the expression of IL-4 and IL-5 compared with the only PM₁.₀ or ALL treatment. Interestingly, IL-13 that is necessary for allergen-induced airway hyper responsiveness, is increased in cells treated with PM₁.₀ + ALL together, but is higher expressed when the cells are treated only with the allergen. Our data support the hypothesis that the urban environment damage the acinar lung units and activates cells of the immune system.
Afficher plus [+] Moins [-]Ozone uptake by adult urban trees based on sap flow measurement
2012
Wang, Hua | Zhou, Weiqi | Wang, Xiaoke | Gao, Fuyuan | Zheng, Hua | Tong, Lei | Ouyang, Z. (Zhiyun)
The O₃ uptake in 17 adult trees of six urban species was evaluated by the sap flow-based approach under free atmospheric conditions. The results showed very large species differences in ground area scaled whole-tree ozone uptake ( [Formula: see text] ), with estimates ranging from 0.61 ± 0.07 nmol m⁻² s⁻¹ in Robinia pseudoacacia to 4.80 ± 1.04 nmol m⁻² s⁻¹ in Magnolia liliiflora. However, average [Formula: see text] by deciduous foliages was not significantly higher than that by evergreen ones (3.13 vs 2.21 nmol m⁻² s⁻¹, p = 0.160). Species of high canopy conductance for O₃ ( [Formula: see text] ) took up more O₃ than those of low [Formula: see text] , but that their sensitivity to vapour pressure deficit (D) were also higher, and their [Formula: see text] decreased faster with increasing D, regardless of species. The responses of [Formula: see text] to D and total radiation led to the relative high flux of O₃ uptake, indicating high ozone risk for urban tree species.
Afficher plus [+] Moins [-]Accumulation of dioxins and induction of cytochrome P450 1A4/1A5 enzyme activities in common cormorants from Lake Biwa, Japan: Temporal trends and validation of national regulation on dioxins emission
2012
Kubota, Akira | Watanabe, Michio X. | Kim, Eun-Young | Yoneda, Kumiko | Tanabe, Shinsuke | Iwata, Hisato
To validate the outcome of the national regulation on dioxins emission implemented in 1999, this study investigated temporal trends of chlorinated dioxins and related compounds (DRCs) in liver of common cormorants (Phalacrocorax carbo) collected from Lake Biwa, Japan between 2001 and 2008, as a part of the “Survey on the State of Dioxins Accumulation in Wildlife” conducted by the Ministry of the Environment, Japan. We also measured a biomarker of DRCs exposure, the cytochrome P450 1A (CYP1A)-dependent O-dealkylation activity of alkoxyresorufins (AROD), including methoxy-, ethoxy-, pentoxy- and benzyloxy-resorufins in the samples over 2001–2007. Neither TEQ nor AROD activity showed any clear declining trend over the time period, although the emission of DRCs during the corresponding period was estimated to be apparently decreasing. Our data indicate that the concentration of recalcitrant DRCs in the cormorant during 2001–2008 was scarcely affected by the national regulation on dioxins emission.
Afficher plus [+] Moins [-]Distribution of PCDD/Fs and organometallic compounds in sewage sludge of wastewater treatment plants in China
2012
Lu, Mang | Wu, Xue-Jiao | Zeng, De-Cai | Liao, Yong
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), organotin and organolead compounds were measured in sewage sludge samples collected from 24 wastewater treatment plants from 18 cities of 13 provinces in China. Total international toxicity equivalent (I-TEQ) values were evaluated for PCDD/Fs. The total concentration of PCDD/Fs ranged from 104.0 to 1661 pg/g dry weight (d.w.) and 2.51–75.21 pg I-TEQ/g d.w., indicating that all I-TEQs were below Chinese legislation limit value regulated for land application. The concentrations ranged from 258 to 3886, 126 to 1129, and 84–2133 ng/g as Sn d.w., for tributyltin (TBT), dibutyltin (DBT), and diphenyltin (DPhT), respectively. On the other side, organolead concentrations ranged from 85 to 668 with an average of 279 ng/g as lead. High concentrations of organolead compounds in sewage sludge indicated that the environmental impact of organolead compounds remains in China.
Afficher plus [+] Moins [-]Polycyclic aromatic hydrocarbons (PAHs) in continental shelf sediment of China: Implications for anthropogenic influences on coastal marine environment
2012
Liu, Liang-Ying | Wang, Ji-Zhong | Wei, Gao-Ling | Guan, Yu-Feng | Zeng, E. Y. (Eddy Y.)
Sediments collected from the continental shelf of China, embracing Yellow Sea, inner shelf of the East China Sea (ECS), and the South China Sea (SCS), were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of anthropogenic PAHs (Σ₁₈PAH) were 27–224 ng/g dry weight, with an average of 82 ng/g. Sedimentary PAHs in the continental shelf off China were mainly derived from mixed residues of biomass, coal, and petroleum combustion. Fluvial transport and atmospheric deposition mainly accounted for sediment PAHs in the ECS inner shelf and Yellow Sea (and the SCS), respectively. Furthermore, statistically higher levels of Σ₁₈PAH (28–224 ng/g; mean 110 ng/g) in the Yellow Sea sediment than in the SCS sediment (28–109 ng/g; mean 58 ng/g) were probably resulted from higher PAH emissions from coke industry and domestic coal combustion in North China than in South China.
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