Refinar búsqueda
Resultados 371-380 de 2,512
Species composition of a soil invertebrate multi-species test system determines the level of ecotoxicity Texto completo
2014
Sechi, Valentina | D'Annibale, Alessandra | Maraldo, Kristine | Johansen, Anders | Bossi, Rossana | Jensen, John | Krogh, Paul Henning
A soil multi-species, SMS, experimental test system consisting of the natural microbial community, five collembolan species and a predatory mite along with either Enchytraeus crypticus or the earthworm Eisenia fetida were exposed to α-cypermethrin. A comparison of the performance of these two types of SMSs is given to aid the development of a standard test system. E. fetida had a positive effect on the majority of the species, reducing the negative insecticide effect. E. fetida affected the species sensitivity and decreased the degradation of the insecticide due to the organic matter incorporation of earthworm food. After 8 weeks, the EC50 was 0.76 mg kg−1 for enchytraeids and ranged between 2.7 and 18.9 mg kg−1 for collembolans, more sensitive than previously observed with single species. Changes observed in the community structure and function illustrates the strength of a multi-species test system as an ecotoxicological tool compared to single species tests.
Mostrar más [+] Menos [-]Biodegradability of pharmaceutical compounds in agricultural soils irrigated with treated wastewater Texto completo
2014
Grossberger, Amnon | Hadar, Y. (Yitzhak) | Borch, Thomas | Chefetz, Benny
Pharmaceutical compounds (PCs) are introduced into agricultural soils via irrigation with treated wastewater (TWW). Our data show that carbamazepine, lamotrigine, caffeine, metoprolol, sulfamethoxazole and sildenafil are persistent in soils when introduced via TWW. However, other PCs, namely diclofenac, ibuprofen, bezafibrate, gemfibrozil and naproxen were not detected in soils when introduced via TWW. This is likely due to rapid degradation as confirmed in our microcosm studies where they exhibited half-lives (t1/2) between 0.2–9.5 days when soils were spiked at 50 ng/g soil and between 3 and 68 days when soils were spiked at 5000 ng/g soil. The degradation rate and extent of PCs observed in microcosm studies were similar in soils that had been previously irrigated with TWW or fresh water. This suggests that pre-exposure of the soils to PCs via irrigation with TWW does not enhance their biodegradation. This suggests that PCs are probably degraded in soils via co-metabolism.
Mostrar más [+] Menos [-]Particle-bound PAHs quantification using a 3-stages cascade impactor in French indoor environments Texto completo
2014
Liaud, Céline | Dintzer, Thierry | Tschamber, Valérie | Trouve, Gwénaëlle | Le Calvé, Stéphane
Cascade Impactor is a powerful sampling method to collect airborne particles as a function of their size. The 3-stages Cascade Impactor used in this study allowed to sample simultaneously particles with aerodynamic diameter Dae > 10 μm, 2.5 μm < Dae < 10 μm, 1 μm < Dae < 2.5 μm and Dae < 1 μm. Once collected individual concentrations of the 16 US-EPA priority Polycyclic Aromatic Hydrocarbons (PAHs) bound to particles were quantified for 8 different indoor environments located in Strasbourg area in France. All the heavy PAHs owning between 4 and 6 aromatic rings were detected in all of the 8 sampling sites. The total PAHs concentration varied from 0.44 to 2.09 ng m−3 for a low-energy building school and a smoking apartment, respectively. Results revealed also that high molecular weight PAHs were mainly associated to the finest particles. Our data are consistent with those measured elsewhere in European indoor environments.
Mostrar más [+] Menos [-]Spatial and temporal trends in brominated flame retardants in seabirds from the Pacific coast of Canada Texto completo
2014
Miller, Aroha | Elliott, John E. | Elliott, Kyle H. | Guigueno, Mélanie F. | Wilson, Laurie K. | Lee, Sandi | Idrissi, Abde
Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) are bioaccumulative flame retardants. PBDEs increased in many ecosystems during the late 20th century, but recently have declined in some environments. To examine trends in the northern Pacific, we analysed PBDEs, HBCDD and carbon and nitrogen stable isotopes (δ13C and δ15N) to account for dietary effects in archived eggs of three seabird species from British Columbia, Canada, 1990–2011 (rhinoceros auklets, Cerorhinca monocerata; Leach's storm-petrels, Oceanodroma leucorhoa; ancient murrelets, Synthliboramphus antiquus, 2009 only). PBDEs increased until approximately 2000 and then decreased, while HBCDD increased exponentially throughout the examined period. No significant changes in dietary tracers were observed. HBCDD and ΣPBDE levels varied among species; ΣPBDE also varied among sites. Temporal changes in contaminant concentrations are unlikely to have been caused by dietary changes, and likely reflect the build-up followed by decreases associated with voluntary phase-outs and regulations implemented in North America to control PBDEs.
Mostrar más [+] Menos [-]Setting ozone critical levels for protecting horticultural Mediterranean crops: Case study of tomato Texto completo
2014
González Fernández, I. | Calvo, E. | Gerosa, G. | Bermejo, V. | Marzuoli, R. | Calatayud, V. | Alonso, R.
Seven experiments carried out in Italy and Spain have been used to parameterising a stomatal conductance model and establishing exposure– and dose–response relationships for yield and quality of tomato with the main goal of setting O3 critical levels (CLe). CLe with confidence intervals, between brackets, were set at an accumulated hourly O3 exposure over 40 nl l−1, AOT40 = 8.4 (1.2, 15.6) ppm h and a phytotoxic ozone dose above a threshold of 6 nmol m−2 s−1, POD6 = 2.7 (0.8, 4.6) mmol m−2 for yield and AOT40 = 18.7 (8.5, 28.8) ppm h and POD6 = 4.1 (2.0, 6.2) mmol m−2 for quality, both indices performing equally well. CLe confidence intervals provide information on the quality of the dataset and should be included in future calculations of O3 CLe for improving current methodologies.These CLe, derived for sensitive tomato cultivars, should not be applied for quantifying O3-induced losses at the risk of making important overestimations of the economical losses associated with O3 pollution.
Mostrar más [+] Menos [-]Highlighting the threat from current and near-future ozone pollution to clover in pasture Texto completo
2014
Hewitt, D.K.L. | Mills, G. | Hayes, F. | Wilkinson, S. | Davies, W.
Globally, the legume–rhizobia symbiosis, contained within specialised organs called root nodules, is thought to add at least 30 Tg N annually to agricultural land. The growth and functioning of a modern white clover (Trifolium repens cv. Crusader) and red clover (T. pratense cv. Merviot) cultivar were investigated in current and future ozone scenarios in solardomes. Both cultivars developed leaf injury and had significant reductions in root biomass and root nodule number in response to ozone, with Crusader also displaying a reduced size and mass of nodules. In-situ measurements of N-fixation in Crusader by acetylene reduction assay revealed reduced N-fixation rates in a future scenario with an increased background and moderate peaks of ozone. The implications for the sustainability of temperate pasture are discussed.
Mostrar más [+] Menos [-]Characterization of estrogen receptor α activities in polychlorinated biphenyls by in vitro dual-luciferase reporter gene assay Texto completo
2014
Zhang, Quan | Lu, Meiya | Wang, Cui | Du, Jie | Zhou, Peixue | Zhao, Meirong
Polychlorinated biphenyls (PCBs) are thought to cause adverse health effects, particularly endocrine disruption. However, results on the estrogenic activities of a large set of PCB congeners through hormone receptors have not been fully studied. In this study, we evaluated the anti/estrogenic effects of 20 PCBs using an in vitro dual-luciferase reporter gene assay. PCB 18, 28, 49, 52, 99, 101, 103, 110, and 128 exhibited estrogenic effects, whereas PCB 118, 138, 163, 170, 180, 187, 194, 199 and 203 behaved as anti-estrogens. In particular, PCB 30 and 44 exhibited both agonistic and antagonistic activities in the dual-luciferase reporter gene assay. The results obtained from the dual-luciferase reporter gene assay, yeast two-hybrid assay and E-SCREEN were compared, suggesting that the dual-luciferase reporter gene assay is a useful approach for high-throughput screening. We also predicted the possible relationship between the chemical structures and the estrogenic effects of PCBs.
Mostrar más [+] Menos [-]Pyruvate carboxylase as a sensitive protein biomarker for exogenous steroid chemicals Texto completo
2014
Liang, Xue-fang | Martyniuk, Christopher J. | Cheng, Gang | Zha, Jinmiao | Wang, Zijian
Assessing protein responses to endocrine disrupting chemicals is critical for understanding the mechanisms of chemical action and for the assessment of hazards. In this study, the response of the liver proteome of male rare minnows (Gobiocypris rarus) treated with 17β-estradiol (E2) and females treated with 17α-methyltestosterone (MT) were analyzed. A total of 23 and 24 proteins were identified with differential expression in response to E2 and MT, respectively. Pyruvate carboxylase (PC) was the only common differentially expressed protein in both males and females after E2- and MT-treatments. The mRNA as well as the protein levels of PC were significantly down-regulated compared with that of the controls (p < 0.05). Our results suggest that endocrine disruptors interfere with genes and proteins of the TCA cycle and PC may be a sensitive biomarker of exposure to exogenous steroid chemicals in the liver of fish.
Mostrar más [+] Menos [-]The characteristics of Beijing aerosol during two distinct episodes: Impacts of biomass burning and fireworks Texto completo
2014
Cheng, Yuan | Engling, Guenter | He, Ke-bin | Duan, Feng-kui | Du, Zhen-yu | Ma, Yong-Liang | Liang, Lin-lin | Lu, Zi-feng | Liu, Jiu-meng | Zheng, Mei | Weber, Rodney J.
The chemical composition of Beijing aerosol was measured during summer and winter. Two distinct episodes were identified. Water-soluble potassium (K+) increased significantly during the firework episode in winter with an episode to non-episode ratio of 4.97, whereas the biomass burning (BB) episode in summer was characterized by high episode to non-episode ratios of levoglucosan (6.38) and K+ (6.90). The BB and firework episodes had only a minor influence on the water-soluble OC (organic carbon) to OC ratio. Based on separate investigations of episode and non-episode periods, it was found that: (i) sulfate correlated strongly with both relative humidity and nitrate during the typical winter period presumably indicating the importance of the aqueous-phase oxidation of sulfur dioxide by nitrogen dioxide, (ii) oxalate and WSOC during both winter and summer in Beijing were mainly due to secondary formation, and (iii) high humidity can significantly enhance the formation potential of WSOC in winter.
Mostrar más [+] Menos [-]Why small and medium chemical companies continue to pose severe environmental risks in rural China Texto completo
2014
He, Guizhen | Zhang, Lei | Mol, Arthur P.J. | Wang, Tieyu | Lü, Yonglong
In China, rural chemical SMEs are often believed to still largely operate below the sustainability radar. This paper investigates to what extent and how chemical SMEs are already experiencing pressure to improve their environmental performance, using an in-depth case study in Jasmine County, Hebei province. The results show that local residents had rather low trust in the environmental improvement promises made by the enterprises and the local government, and disagreed with the proposed improvement plans. Although the power of local residents to influence decision making remained limited, the chemical SMEs started to feel increasing pressures to clean up their business, from governments, local communities and civil society, and international value chain stakeholders. Notwithstanding these mounting pressures chemical SME's environmental behavior and performance has not changed radically for the better. The strong economic ties between local county governments and chemical SMEs continue to be a major barrier for stringent environmental regulation.
Mostrar más [+] Menos [-]