خيارات البحث
النتائج 121 - 130 من 753
Interactions between plant and rhizosphere microbial communities in a metalliferous soil النص الكامل
2010
Epelde, Lur | Becerril, José M. | Barrutia, Oihana | González-Oreja, José A. | Garbisu, Carlos
In the present work, the relationships between plant consortia, consisting of 1-4 metallicolous pseudometallophytes with different metal-tolerance strategies (Thlaspi caerulescens: hyperaccumulator; Jasione montana: accumulator; Rumex acetosa: indicator; Festuca rubra: excluder), and their rhizosphere microbial communities were studied in a mine soil polluted with high levels of Cd, Pb and Zn. Physiological response and phytoremediation potential of the studied pseudometallophytes were also investigated. The studied metallicolous populations are tolerant to metal pollution and offer potential for the development of phytoextraction and phytostabilization technologies. T. caerulescens appears very tolerant to metal stress and most suitable for metal phytoextraction; the other three species enhance soil functionality. Soil microbial properties had a stronger effect on plant biomass rather than the other way around (35.2% versus 14.9%). An ecological understanding of how contaminants, ecosystem functions and biological communities interact in the long-term is needed for proper management of these fragile metalliferous ecosystems.
اظهر المزيد [+] اقل [-]Environmental monitoring of Domingo Rubio stream (Huelva Estuary, SW Spain) by combining conventional biomarkers and proteomic analysis in Carcinus maenas النص الكامل
2010
Montes Nieto, Rafael | García Barrera, Tamara | Gómez-Ariza, José-Luis | López-Barea, Juan
Element load, conventional biomarkers and altered protein expression profiles were studied in Carcinus maenas crabs, to assess contamination of “Domingo Rubio” stream, an aquatic ecosystem that receives pyritic metals, industrial contaminants, and pesticides. Lower antioxidative activities – glucose-6-phosphate and 6-phosphogluconate dehydrogenases, catalase – were found in parallel to higher levels of damaged biomolecules – malondialdehyde, oxidized glutathione –, due to oxidative lesions promoted by contaminants, as the increased levels of essential – Zn, Cu, Co – and nonessential – Cr, Ni, Cd – elements. Utility of Proteomics to assess environmental quality was confirmed, especially after considering the six proteins identified by de novo sequencing through capLC-μESI-ITMS/MS and homology search on databases. They include tripartite motif-containing protein 11 and ATF7 transcription factor (upregulated), plus CBR-NHR-218 nuclear hormone receptor, two components of the ABC transporters and aldehyde dehydrogenase (downregulated). These proteins could be used as novel potential biomarkers of the deleterious effects of pollutants present in the area.
اظهر المزيد [+] اقل [-]Plant and fungal biodiversity from metal mine wastes under remediation at Zimapan, Hidalgo, Mexico النص الكامل
2010
Pilar Ortega-Larrocea, María del | Xoconostle-Cázares, Beatriz | Maldonado-Mendoza, Egnacio E. | Carrillo González, Rogelio | Hernández-Hernández, Jani | Díaz Garduño, Margarita | López-Meyer, Melina | Gómez-Flores, Lydia | González-Chávez, Ma. del Carmen A.
Plant establishment, presence of arbuscular mycorrhizal fungi (AMF) and other rhizospheric fungi were studied in mine wastes from Zimapan, Hidalgo state, Mexico, using a holistic approach. Two long-term afforested and three non-afforested mine tailings were included in this research. Fifty-six plant species belonging to 29 families were successfully established on the afforested sites, while unmanaged tailings had only a few native plant species colonizing the surrounding soils. Almost all plant roots collected were associated to AMF in these sites. The genus Glomus was the most abundant AMF species found in their rhizosphere; however, the Acaulospora genus was also observed. Other rhizospheric fungi were identified by 18S rDNA sequencing analysis. Their role in these substrates, i.e. biocontrol, pollutant- and organic matter-degradation, and aides that increase plant metal tolerance is discussed. Our results advance the understanding of fungal diversity in sites polluted with metals and present alternative plants for remediation use.
اظهر المزيد [+] اقل [-]Hydroxypropyl-β-cyclodextrin as non-exhaustive extractant for organochlorine pesticides and polychlorinated biphenyls in muck soil النص الكامل
2010
Wong, Fiona | Bidleman, Terry F.
Hydroxypropyl-β-cyclodextrin (HPCD) was used as a non-exhaustive extractant for organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in muck soil. An optimized extraction method was developed which involved using a HPCD to soil mass ratio of 5.8 with a single extraction period of 20 h. An aging experiment was performed by spiking a muck soil with 13C-labeled OCs and non-labeled PCBs. The soil was extracted with the optimized HPCD method and Soxhlet apparatus with dichloromethane over 550 d periodically. The HPCD extractability of the spiked OCs was greater than of the native OCs. A decreased in HPCD extractability was observed for the spiked OCs after 550 d of aging and their extractability approached those of the natives. The partition coefficient between HPCD and soil (log KCD-Soil) was negatively correlated with the octanol-water partition coefficient (log KOW) with r2 = 0.67 and p < 0.05.
اظهر المزيد [+] اقل [-]Stable isotope signatures reflect competitiveness between trees under changed CO2/O3 regimes النص الكامل
2010
Grams, T.E.E. | Matyssek, R.
Here we synthesize key findings from a series of experiments to gain new insight on inter-plant competition between juvenile beech (Fagus sylvatica) and spruce (Picea abies) under the influence of increased O3 and CO2 concentrations. Competitiveness of plants was quantified and mechanistically interpreted as space-related resource investments and gains. Stable isotopes were addressed as temporal integrators of plant performance, such as photosynthesis and its relation to water use and nitrogen uptake. In the weaker competitor, beech, efficiency in space-related aboveground resource investment was decreased in competition with spruce and positively related to Δ13C, as well as stomatal conductance, but negatively related to δ18O. Likewise, our synthesis revealed that strong belowground competition for water in spruce was paralleled in this species by high N assimilation capacity. We suggest combining the time-integrative potential of stable isotopes with space-related investigations of competitiveness to accomplish mechanistic understanding of plant competition for resources. Combination of space-related concepts of competitiveness with stable isotopes has potential to clarify mechanisms of competition.
اظهر المزيد [+] اقل [-]Airborne particulate matter from livestock production systems: A review of an air pollution problem النص الكامل
2010
Cambra-López, Maria | Aarnink, André J.A. | Zhao, Yang | Calvet, Salvador | Torres, Antonio G.
Livestock housing is an important source of emissions of particulate matter (PM). High concentrations of PM can threaten the environment, as well as the health and welfare of humans and animals. Particulate matter in livestock houses is mainly coarse, primary in origin, and organic; it can adsorb and contain gases, odorous compounds, and micro-organisms, which can enhance its biological effect. Levels of PM in livestock houses are high, influenced by kind of housing and feeding, animal type, and environmental factors. Improved knowledge on particle morphology, primarily size, composition, levels, and the factors influencing these can be useful to identify and quantify sources of PM more accurately, to evaluate their effects, and to propose adequate abatement strategies in livestock houses. This paper reviews the state-of-the-art of PM in and from livestock production systems. Future research to characterize and control PM in livestock houses is discussed. Control of particulate matter emissions, a major challenge to modern livestock production.
اظهر المزيد [+] اقل [-]Sorptive domains of pine chars as probed by benzene and nitrobenzene النص الكامل
2010
Zhou, Zunlong | Shi, Dongjin | Qiu, Yuping | Sheng, G Daniel
Chars were generated by pyrolyzing pine wood at temperatures between 300 °C and 700 °C for 6 h and at 500 °C for 10–300 min. Their organic content and surface acidity decreased, and BET surface area increased, with increasing pyrolytic temperature and time. The uptake of benzene and nitrobenzene increased with increasing pyrolytic temperature and time with isotherms characterized by a transition from less to more concave-downward. The isotherms with low-temperature and short-time chars were fitted to the dual Langmuir-partition model, whereas those with high-temperature chars to the dual-Langmuir model. Calculations suggest that the organic phases of chars functioned as partition media and the uptake of benzene and nitrobenzene on carbonized chars occurred first in micropores via pore-filling and later in larger pores through capillary condensation and adsorption. It is concluded that chars may be considered to consist of the partition domain, the high-energy micropores domain and the low-energy large pores domain. Pine chars consist of the partition domain, the micropores domain and the large pores domain in terms of organic contaminant uptake.
اظهر المزيد [+] اقل [-]Alteration of sediment organic matter in sediment microbial fuel cells النص الكامل
2010
Hong, Seok Won | Kim, Han S. | Chung, Tai Hak
The alteration of physico-chemical properties of sediment organic matter (SOM) incubated under current-harvesting conditions as well as no-current producing conditions over 120 days using sediment microbial fuel cell systems was examined. The SOM was microbially oxidized under anaerobic conditions with an electrode serving as a terminal electron acceptor. It was found that SOM around the electrochemically-active electrodes became more humified, aromatic, and polydispersed, and had a higher average molecular weight, along with its partial degradation and electricity generation compared to that for the original sediment. These changes in SOM properties were analogous to those commonly observed in the early stages of the SOM diagenetic process (i.e. humification). Such a humification-like process was evidently more stimulated when electrical current was produced than no-current condition. These new findings associated with microbially-catalyzed electricity generation may present a potential for the energy-efficient remediation, monitoring, and/or management of the geo-environment. Sediment microbial fuel cells can stimulate the humification of sediment organic matter.
اظهر المزيد [+] اقل [-]Influence of the nature of soil organic matter on the sorption behaviour of pentadecane as determined by PLS analysis of mid-infrared DRIFT and solid-state 13C NMR spectra النص الكامل
2010
Ehlers, G.A Clark | Forrester, Sean T. | Scherr, Kerstin E. | Loibner, Andreas P. | Janik, L. J. (Les J)
The nature of soil organic matter (SOM) functional groups associated with sorption processes was determined by correlating partitioning coefficients with solid-state 13C nuclear magnetic resonance (NMR) and diffuse reflectance mid-infrared (DRIFT) spectral features using partial least squares (PLS) regression analysis. Partitioning sorption coefficients for n-pentadecane (n-C15) were determined for three alternative models: the Langmuir model, the dual distributed reactive domain model (DRDM) and the Freundlich model, where the latter was found to be the most appropriate. NMR-derived constitutional descriptors did not correlate with Freundlich model parameters. By contrast, PLS analysis revealed the most likely nature of the functional groups in SOM associated with n-C15 sorption coefficients (KF) to be aromatic, possibly porous soil char, rather than aliphatic organic components for the presently investigated soils. High PLS cross-validation correlation suggested that the model was robust for the purpose of characterising the functional group chemistry important for n-C15 sorption. NMR/IR spectroscopy and chemometrics reveal the aromatic fraction of soil organic matter being responsible for alkane sorption.
اظهر المزيد [+] اقل [-]Arsenic contamination and potential health risk implications at an abandoned tungsten mine, southern China النص الكامل
2010
Liu, Chuan-ping | Luo, Chun-ling | Gao, Yun | Li, Fang-bai | Lin, Lan-wen | Wu, Chang'an | Li, Xiang-Dong
In an extensive environmental study, field samples, including soil, water, rice, vegetable, fish, human hair and urine, were collected at an abandoned tungsten mine in Shantou City, southern China. Results showed that arsenic (As) concentration in agricultural soils ranged from 3.5 to 935 mg kg−1 with the mean value of 129 mg kg−1. In addition, As concentration reached up to 325 μg L−1 in the groundwater, and the maximum As concentration in local food were 1.09, 2.38 and 0.60 mg kg−1 for brown rice, vegetable and fish samples, respectively, suggesting the local water resource and food have been severely contaminated with As. Health impact monitoring data revealed that As concentrations in hair and urine samples were up to 2.92 mg kg−1 and 164 μg L−1, respectively, indicating a potential health risk among the local residents. Effective measurements should be implemented to protect the local community from the As contamination in the environment. It is the first report on arsenic contamination and potential health risk implications at abandoned Lianhuashan tungsten mine.
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