Refinar búsqueda
Resultados 451-460 de 3,208
Urban rivers as hotspots of regional nitrogen pollution Texto completo
2015
Zhang, Xiaohong | Wu, Yiyun | Gu, Baojing
Excess nitrogen inputs to terrestrial ecosystems via human activities have deteriorated water qualities on regional scales. Urban areas as settlements of over half global population, however, were usually not considered in the analysis of regional water pollution. Here, we used a 72-month monitoring data of water qualities in Hangzhou, China to test the role of urban rives in regional nitrogen pollution and how they response to the changes of human activities. Concentrations of ammonium nitrogen in urban rivers were 3–5 times higher than that in regional rivers. Urban rivers have become pools of reactive nitrogen and hotspots of regional pollution. Moreover, this river pollution is not being measured by current surface water monitoring networks that are designed to measure broader regional patterns, resulting in an underestimation of regional pollution. This is crucial to urban environment not only in China, but also in other countries, where urban rivers are seriously polluted.
Mostrar más [+] Menos [-]Spatial analysis of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (Sea-Nine 211) concentrations and probabilistic risk to marine organisms in Hiroshima Bay, Japan Texto completo
2015
Mochida, Kazuhiko | Hano, Takeshi | Onduka, Toshimitsu | Ichihashi, Hideki | Amano, Haruna | Ito, Mana | Ito, Katsutoshi | Tanaka, Hiroyuki | Fujii, Kazunori
We analyzed the spatial distribution of an antifouling biocide, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (Sea-Nine 211) in the surface water and sediments of Hiroshima Bay, Japan to determine the extent of contamination by this biocide. A quantitative estimate of the environmental concentration distribution (ECD) and species sensitivity distributions (SSDs) for marine organisms were derived by using a Bayesian statistical model to carry out a probabilistic ecological risk analysis, such as calculation of the expected potentially affected fraction (EPAF). The spatial distribution analysis supported the notion that Sea-Nine 211 is used mainly for treatment of ship hulls in Japan. The calculated EPAF suggests that approximately up to a maximum of 0.45% of marine species are influenced by the toxicity of Sea-Nine 211 in Hiroshima Bay. In addition, estimation of the ecological risk with a conventional risk quotient method indicated that the risk was a cause for concern in Hiroshima Bay.
Mostrar más [+] Menos [-]Exposure to environmentally-relevant levels of ozone negatively influence pollen and fruit development Texto completo
2015
Gillespie, Colin | Stabler, Daniel | Tallentire, Eva | Goumenaki, Eleni | Barnes, Jeremy
A combination of in vitro and in vivo studies on tomato (Lycopersicon esculentum Mill. cv. Triton) revealed that environmentally-relevant levels of ozone (O3) pollution adversely affected pollen germination, germ tube growth and pollen-stigma interactions – pollen originating from plants raised in charcoal-Purafil® filtered air (CFA) exhibited reduced germ tube development on the stigma of plants exposed to environmentally-relevant levels of O3. The O3-induced decline in in vivo pollen viability was reflected in increased numbers of non-fertilized and fertilized non-viable ovules in immature fruit. Negative effects of O3 on fertilization occurred regardless of the timing of exposure, with reductions in ovule viability evident in O3 × CFA and CFA × O3 crossed plants. This suggests O3-induced reductions in fertilization were associated with reduced pollen viability and/or ovule development. Fruit born on trusses independently exposed to 100 nmol mol−1 O3 (10 h d−1) from flowering exhibited a decline in seed number and this was reflected in a marked decline in the weight and size of individual fruit – a clear demonstration of the direct consequence of the effects of the pollutant on reproductive processes. Ozone exposure also resulted in shifts in the starch and ascorbic acid (Vitamin C) content of fruit that were consistent with accelerated ripening. The findings of this study draw attention to the need for greater consideration of, and possibly the adoption of weightings for the direct impacts of O3, and potentially other gaseous pollutants, on reproductive biology during ‘risk assessment’ exercises.
Mostrar más [+] Menos [-]Environmental health hazards of e-cigarettes and their components: Oxidants and copper in e-cigarette aerosols Texto completo
2015
Lerner, Chad A. | Sundar, Isaac K. | Watson, Richard M. | Elder, Alison | Jones, Ryan | Done, Douglas | Kurtzman, Rachel | Ossip, Deborah J. | Robinson, Risa | McIntosh, Scott | Rahman, Irfan
To narrow the gap in our understanding of potential oxidative properties associated with Electronic Nicotine Delivery Systems (ENDS) i.e. e-cigarettes, we employed semi-quantitative methods to detect oxidant reactivity in disposable components of ENDS/e-cigarettes (batteries and cartomizers) using a fluorescein indicator. These components exhibit oxidants/reactive oxygen species reactivity similar to used conventional cigarette filters. Oxidants/reactive oxygen species reactivity in e-cigarette aerosols was also similar to oxidant reactivity in cigarette smoke. A cascade particle impactor allowed sieving of a range of particle size distributions between 0.450 and 2.02 μm in aerosols from an e-cigarette. Copper, being among these particles, is 6.1 times higher per puff than reported previously for conventional cigarette smoke. The detection of a potentially cytotoxic metal as well as oxidants from e-cigarette and its components raises concern regarding the safety of e-cigarettes use and the disposal of e-cigarette waste products into the environment.
Mostrar más [+] Menos [-]Impact of 70 years urban growth associated with heavy metal pollution Texto completo
2015
Rodríguez Martín, J.A. | De Arana, C. | Ramos-Miras, J.J. | Gil, C. | Boluda, R.
Impact of 70 years urban growth associated with heavy metal pollution Texto completo
2015
Rodríguez Martín, J.A. | De Arana, C. | Ramos-Miras, J.J. | Gil, C. | Boluda, R.
Historical trends in trace element deposition were analyzed using herbaria specimens. We determined Al, Fe, Mg, Mn, Ca, Na, P, K, S, As, Cd, Cr, Cu, Ni, Pb and Zn contents in leaves of eight specimens collected in 1941. To assess changes, we collected the same plants from a botanical garden in 2012. The concentrations of major elements showed large species variability. However, temporal trends were predominately detected for heavy metals. The Cd, Ni and Cr contents in the 2012 leaves were 10, 13 and 16 times higher, respectively, than in 1941. Urban activities have substantially raised the levels of these metals in urban atmospheres due to changes in human activities over 70 years of urban growth. Nevertheless, Pb has decreased (−126%) in recent decades thanks to controlled lead fuel combustion. In short, metal deposition trend to increase Cr, Ni and Cd levels.
Mostrar más [+] Menos [-]Impact of 70 years urban growth associated with heavy metal pollution Texto completo
2015
Rodríguez Martín, José Antonio | De Arana, C. | Ramos-Miras, José Joaquín | Gil, Carlos | Boluda, Rafael | Gil, Carlos [0000-0002-9903-1303] | Ramos-Miras, José Joaquín [0000-0001-6194-7191] | Boluda, Rafael [0000-0001-7682-758X]
Historical trends in trace element deposition were analyzed using herbaria specimens. We determined Al, Fe, Mg, Mn, Ca, Na, P, K, S, As, Cd, Cr, Cu, Ni, Pb and Zn contents in leaves of eight specimens collected in 1941. To assess changes, we collected the same plants from a botanical garden in 2012. The concentrations of major elements showed large species variability. However, temporal trends were predominately detected for heavy metals. The Cd, Ni and Cr contents in the 2012 leaves were 10, 13 and 16 times higher, respectively, than in 1941. Urban activities have substantially raised the levels of these metals in urban atmospheres due to changes in human activities over 70 years of urban growth. Nevertheless, Pb has decreased (−126%) in recent decades thanks to controlled lead fuel combustion. In short, metal deposition trend to increase Cr, Ni and Cd levels. © 2014 Elsevier Ltd | Peer reviewed
Mostrar más [+] Menos [-]Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment Texto completo
2015
Côte, Jessica | Bouétard, Anthony | Pronost, Yannick | Besnard, Anne-Laure | Coke, Maïra | Piquet, Fabien | Caquet, Thierry | Coutellec, Marie-Agnès
Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment Texto completo
2015
Côte, Jessica | Bouétard, Anthony | Pronost, Yannick | Besnard, Anne-Laure | Coke, Maïra | Piquet, Fabien | Caquet, Thierry | Coutellec, Marie-Agnès
The use of standardized monospecific testing to assess the ecological risk of chemicals implicitly relies on the strong assumption that intraspecific variation in sensitivity is negligible or irrelevant in this context. In this study, we investigated genetic variation in copper sensitivity of the freshwater snail Lymnaea stagnalis, using lineages stemming from eight natural populations or strains found to be genetically differentiated at neutral markers. Copper-induced mortality varied widely among populations, as did the estimated daily death rate and time to 50% mortality (LT50).Population genetic divergence in copper sensitivity was compared to neutral differentiation using the QST-FST approach. No evidence for homogenizing selection could be detected. This result demonstrates that species-level extrapolations from single population studies are highly unreliable. The study provides a simple example of how evolutionary principles could be incorporated into ecotoxicity testing in order to refine ecological risk assessment.
Mostrar más [+] Menos [-]Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment | Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment: Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment Texto completo
2015
Côte, Jessica | Bouetard, Anthony | Pronost, Yannick | Besnard, Anne-Laure | Coke, Maïra | Piquet, F. | Caquet, Thierry | Coutellec, Marie-Agnès | Écologie et santé des écosystèmes (ESE) ; Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST | Unité d'Ecologie et Ecotoxicologie Aquatiques (UEEA) ; Institut National de la Recherche Agronomique (INRA) | Institut en Santé Agro-Environnement (ISAE) | Département Ecologie des Forêts, Prairies et milieux Aquatiques (DEPT EFPA) ; Institut National de la Recherche Agronomique (INRA)
INRA-Onema "Phylogeny and Polluosensitivity" program This work was supported by the INRA-Onema 2013-2014 "Phylogeny and Polluosensitivity" program. The authors thank Marc Collinet and Antoine Gallard for technical assistance. Elsevier sci ltd | International audience | The use of standardized monospecific testing to assess the ecological risk of chemicals implicitly relies on the strong assumption that intraspecific variation in sensitivity is negligible or irrelevant in this context. In this study, we investigated genetic variation in copper sensitivity of the freshwater snail Lymnaea stagnalis, using lineages stemming from eight natural populations or strains found to be genetically differentiated at neutral markers. Copper-induced mortality varied widely among populations, as did the estimated daily death rate and time to 50% mortality (LT50). Population genetic divergence in copper sensitivity was compared to neutral differentiation using the Qs-r-FsT approach. No evidence for homogenizing selection could be detected. This result demonstrates that species-level extrapolations from single population studies are highly unreliable. The study provides a simple example of how evolutionary principles could be incorporated into ecotoxicity testing in order to refine ecological risk assessment. (C) 2015 Elsevier Ltd. All rights reserved.
Mostrar más [+] Menos [-]Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter Texto completo
2015
Lohwacharin, J. | Takizawa, S. | Punyapalakul, P.
We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns.
Mostrar más [+] Menos [-]Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: Quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations Texto completo
2015
Gromke, Christof | Blocken, Bert
Flow and dispersion of traffic pollutants in a generic urban neighborhood with avenue-trees were investigated with Computational Fluid Dynamics (CFD). In Part I of this two-part contribution, quality assessment and assurance for CFD simulations in urban and vegetation configurations were addressed, before in Part II flow and dispersion in a generic urban neighborhood with multiple layouts of avenue-trees were studied. In a first step, a grid sensitivity study was performed that inferred that a cell count of 20 per building height and 12 per canyon width is sufficient for reasonable grid insensitive solutions. Next, the performance of the realizable k-ε turbulence model in simulating urban flows and of the applied vegetation model in simulating flow and turbulence in trees was validated. Finally, based on simulations of street canyons with and without avenue-trees, an appropriate turbulent Schmidt number for modeling dispersion in the urban neighborhood was determined as Sct = 0.5.
Mostrar más [+] Menos [-]Effects of nitrogen deposition on carbon cycle in terrestrial ecosystems of China: A meta-analysis Texto completo
2015
Chen, Hao | Li, Dejun | Gurmesa, Geshere A. | Yu, Guirui | Li, Linghao | Zhang, Wei | Fang, Huajun | Mo, Jiangming
Nitrogen (N) deposition in China has increased greatly, but the general impact of elevated N deposition on carbon (C) dynamics in Chinese terrestrial ecosystems is not well documented. In this study we used a meta-analysis method to compile 88 studies on the effects of N deposition C cycling on Chinese terrestrial ecosystems. Our results showed that N addition did not change soil C pools but increased above-ground plant C pool. A large decrease in below-ground plant C pool was observed. Our result also showed that the impacts of N addition on ecosystem C dynamics depend on ecosystem type and rate of N addition. Overall, our findings suggest that 1) decreased below-ground plant C pool may limit long-term soil C sequestration; and 2) it is better to treat N-rich and N-limited ecosystems differently in modeling effects of N deposition on ecosystem C cycle.
Mostrar más [+] Menos [-]Catecholate-siderophore produced by As-resistant bacterium effectively dissolved FeAsO4 and promoted Pteris vittata growth Texto completo
2015
Liu, Xue | Yang, Guang-Mei | Guan, Dong-Xing | Ghosh, Piyasa | Ma, Lena Q.
The impact of siderophore produced by arsenic-resistant bacterium Pseudomonas PG12 on FeAsO4 dissolution and plant growth were examined. Arsenic-hyperaccumulator Pteris vittata was grown for 7 d in 0.2-strength Fe-free Hoagland solution containing FeAsO4 mineral and PG12-siderophore or fungal-siderophore desferrioxamine B (DFOB). Standard siderophore assays indicated that PG12-siderophore was catecholate-type. PG12-siderophore was more effective in promoting FeAsO4 dissolution, and Fe and As plant uptake than DFOB. Media soluble Fe and As in PG12 treatment were 34.6 and 3.07 μM, 1.6- and 1.4-fold of that in DFOB. Plant Fe content increased from 2.93 to 6.24 g kg−1 in the roots and As content increased from 14.3 to 78.5 mg kg−1 in the fronds. Besides, P. vittata in PG12 treatment showed 2.6-times greater biomass than DFOB. While P. vittata fronds in PG12 treatment were dominated by AsIII, those in DFOB treatment were dominated by AsV (61–77%). This study showed that siderophore-producing arsenic-resistant rhizobacteria may have potential in enhancing phytoremediation of arsenic-contaminated soils.
Mostrar más [+] Menos [-]