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1.
Ludovic Besaury Barbara Pawlak Laurent Quillet 《Environmental science and pollution research international》2016,23(5):4013-4023
Microorganisms have developed copper-resistance mechanisms in order to survive in contaminated environments. The abundance and expression of the copper-resistance genes cusA and copA, encoding respectively for a Resistance Cell Nodulation protein and for a P-type ATP-ase pump, was assessed along a gradient of copper concentration in microcosms prepared from Seine estuary mudflat sediment. We demonstrated that the abundance of copA and cusA genes decreased with the increase of copper concentration and that cusA gene was up to ten times higher than the copA gene. Only the copA gene was expressed in both oxic and anoxic conditions. The abundance and activity of the microbial community remained constant whatever the concentrations of copper along the gradient. The molecular phylogeny of the two copper-resistance genes was studied and revealed that the increase of copper increased the diversity of copA and cusA gene sequences. 相似文献
2.
Giloteaux L Solé A Esteve I Duran R 《Environmental science and pollution research international》2011,18(7):1147-1159
Introduction
A Microcoleus sp. consortium, obtained from the Ebro delta microbial mat, was maintained under different conditions including uncontaminated, lead-contaminated, and acidic conditions. 相似文献3.
Ludovic Castro Aurlien Dommergue Christophe Ferrari Laurent Maron 《Atmospheric environment (Oxford, England : 1994)》2009,43(35):5708-5711
In the mid 1980s the study of ozone reactivity gained a significant interest with the discoveries of the stratospheric ozone hole (Farman et al., 1985) and of the ozone depletion events in the polar boundary layer (Oltmans et al., 1989). In the stratosphere, the mechanism involves heterogeneous reactions on polar stratospheric clouds that lead to chlorine activation (Solomon et al., 1986). In contrast, tropospheric ozone depletion occurring during polar springtime rather involves reactive bromine species. They are released during a series of photochemical and heterogeneous reactions often called the bromine explosion (see the review of Simpson et al., 2007). In this reaction sequence, an essential step is the generation of photolyzable Br2, the precursor of two Br atoms, via the multiphasic reaction (1):(1) The production of reactive HOBr could occur with the oxidation of BrO by HO2. 相似文献
HOBr + Br− + H+ → H2O + Br2
4.
Effects of medium-pressure UV lamps radiation on water quality in a chlorinated indoor swimming pool
The aim of our study was to determine the impact of medium-pressure UV lamps radiation on water quality in a chlorinated indoor swimming pool. An indoor swimming pool was equipped with two medium-pressure UV lamps. We collected eight samples of water daily over a four-weeks period and measured total and free chlorine, pH, water temperature, bacteriological parameters, total organic carbon and trihalomethanes. During the first week, which served as control, medium-pressure UV lamps were turned off. During the next three weeks, medium-pressure UV lamps were kept on 24 h per day. The third week, we reduced the level of the injected chlorine into water, and the last week we also reduced the water renewal volume by 27%. Our results showed that bacteriological parameters remained within allowable french limits. When medium-pressure UV lamps were kept on, total, free and active chlorine levels were significantly increased (P<0.001), whereas combined chlorine level were significantly decreased (P<0.001 and P<0.05, respectively). The levels of chloroform and bromodichloromethane were significantly increased when medium-pressure UV lamps were kept on (P<0.001), whereas chlorodibromomethane and bromoform levels significantly decreased (P<0.05 and P<0.001, respectively). The additional formation of chloroform and bromodichloromethane may be explained by the increase in active chlorine and by radicalizing mechanisms initiated by UV radiation. 相似文献
5.
Pankaj Kumar Vandana Mishra Saiyami Bhardwaj Shafali Garg Ludovic F. Dumée Radhey Shyam Sharma 《环境质量管理》2023,32(4):9-17
Sectorial approach for monitoring heavy metal pollution in rivers has failed to report realistic pollution status and associated ecological and human health risks. The increasing spread of heavy metals from different sources and emerging risks to human and environmental health call for reexamining heavy metal pollution monitoring frameworks. Also, the sources, spread, and load of heavy metals in the environment have changed significantly over time, requiring consequent modification in the monitoring frameworks. Therefore, studies on heavy metal monitoring in rivers conducted in the last decade were evaluated for experimental designs, research frameworks, and data presentations. Most studies (∼99%) (i) lacked inclusiveness of all environmental compartments; (ii) focused on “one pollutant – one/two compartment” or sometimes “one pollutant – one compartment – one effect” approach; and (iii) remained “data-rich but information poor.” An ecological approach with integrative system thinking is proposed to develop a holistic approach for monitoring river pollution. It is visualized that heavy metal monitoring, risk analyses, and water management must incorporate tracking pollutants in different environmental compartments of a river (water, sediment, and floodplain/bank soil) and consider correlating it with riverbank land use. The systems-based pollution monitoring and assessment studies will reveal the critical factors that drive heavy metals pollutant movement in ecosystems and associated potential risks to the environment, wildlife, and humans. Also, water quality and pollution indexing tools would help better communicate complex pollution data and associated risks among all stakeholders. Therefore, integrating systems approaches in scientific- and policy-based tools would help sustainably manage the health of rivers, wildlife, and humans. 相似文献
6.
Fungal Degradation of Poly(l-lactide) in Soil and in Compost 总被引:1,自引:1,他引:0
Zoubida Saadi Aurore Rasmont Guy Cesar Hilaire Bewa Ludovic Benguigui 《Journal of Polymers and the Environment》2012,20(2):273-282
The biodegradability of polymers by microorganisms is generally studied in a real environment that contains a natural mixture of fungi and bacteria. The present research mainly focused on the purely fungal degradation of poly(l-lactide), PLLA, to enclose the part of fungi in a real process of biodegradation and to understand the kinetics of biodegradation. Respirometric tests were realized in soil at 30?°C, and in compost at 30?and 58?°C. Results indicated that temperature is the predominant parameter governing the fungal degradation of PLLA. Moreover, in real compost, the biodegradation kinetics of the PLLA revealed a synergy between bacteria and fungi. The curves of PLLA and cellulose biodegradation were modeled by Hill sigmo?d. Fungal degradation was completed by investigating the physical and the chemical properties of the polymer during the process of degradation using several analytical methods such as matrix assisted laser desorption ionization-time of fly spectroscopy, infrared spectroscopy, size exclusion chromatography, and differential scanning calorimetry. These experiments led to a better understanding of the various stages of fungal degradation of PLLA: hydrolysis as well as mineralization. Furthermore, metabolizing products (by-products) of PLLA was investigated also. 相似文献
7.
Boix M Montastruc L Pibouleau L Azzaro-Pantel C Domenech S 《Journal of environmental management》2011,92(7):1802-1808
The optimal design of multicontaminant industrial water networks according to several objectives is carried out in this paper. The general formulation of the water allocation problem (WAP) is given as a set of nonlinear equations with binary variables representing the presence of interconnections in the network. For optimization purposes, three antagonist objectives are considered: F(1), the freshwater flow-rate at the network entrance, F(2), the water flow-rate at inlet of regeneration units, and F(3), the number of interconnections in the network. The multiobjective problem is solved via a lexicographic strategy, where a mixed-integer nonlinear programming (MINLP) procedure is used at each step. The approach is illustrated by a numerical example taken from the literature involving five processes, one regeneration unit and three contaminants. The set of potential network solutions is provided in the form of a Pareto front. Finally, the strategy for choosing the best network solution among those given by Pareto fronts is presented. This Multiple Criteria Decision Making (MCDM) problem is tackled by means of two approaches: a classical TOPSIS analysis is first implemented and then an innovative strategy based on the global equivalent cost (GEC) in freshwater that turns out to be more efficient for choosing a good network according to a practical point of view. 相似文献
8.
Nicolas Picard Steen Magnussen Ludovic Ngok Banak Salomon Namkosserena Yves Yalibanda 《Environmental monitoring and assessment》2010,164(1-4):279-295
Permanent sample plots (PSP), where trees are individually and permanently marked, have received increased interest in Central Africa as a tool to monitor vegetation changes. Although techniques for mounting PSP in tropical forests are well known, their planning still deserves attention. This study aims at defining a rationale for determining the size and number of replicates for setting up PSP in mixed tropical forests. It considers PSP as a sampling plan to estimate a target quantity with its associated margin of error. The target quantity considered here is the stock recovery rate, which is a key parameter for forest management in Central Africa. It is computed separately for each commercial species. The number of trees to monitor for each species defines the margin of error on the stock recovery rate. The size and number of replicated plots is obtained as the solution of an optimization problem that consists in minimizing the margin of error for every species while ensuring that the mounting cost remains below a given threshold. This rationale was applied using the data from the M’Baïki experimental site in the Central African Republic. It showed that the stock recovery rate is a highly variable quantity, and that the typical cost that forest managers are prone to devote to PSP leads to high margins of error. It also showed that the size and number of replicated plots is related to the spatial pattern of trees: clustered or spatially heterogeneous patterns favor many small plots, whereas regular or spatially homogeneous patterns favor few large plots. 相似文献
9.
Perfluorooctanesulfonate (PFOS) is the terminal degradation product of many commercially used perfluorinated compounds, and most of the toxicity testing to date has focused on its potential biological effects. While PFOS has been extensively studied, other PFCs including replacement chemicals such as perfluorobutanesulfonate (PFBS) and perfluorobutyric acid (PFBA), have not been well characterized. Despite the relative lack of data available on these other PFCs it has been assumed that they will cause similar or lesser effects than PFOS. This study compared the effects of 10 PFCs routinely found in the environment on mRNA abundance of 7 genes related to processes known to be affected by PFOS, such as fatty acid and cholesterol synthesis, and thyroid development. Rat H4IIE hepatoma cells were exposed and changes in mRNA abundance were quantified by real-time PCR. Significant changes in mRNA abundance were observed. The effects caused by the shorter chain replacement chemicals differed significantly from those caused by PFOS or PFOA. Furthermore, not all of the PFCs caused the same effects, and changes could not simply be attributed to chain-length or functional group. These differences could mean that these replacement chemicals do not act through the same mechanisms as the more studied PFOS and PFOA. 相似文献
10.
One frequent explanation for the failure of biological invasions is the Allee effect: due to positive density dependence, initially small invading populations may fail to establish and spread. Populations released for biological control are similar to fortuitous invading populations and may therefore suffer from Allee effects. However, unlike fortuitous invasions, biological control allows the experimental manipulation of initial population size and, thus, offers a unique opportunity to test for the occurrence of Allee effects. We manipulated the initial size of 45 populations of a parasitoid wasp introduced for the biological control of a phytophagous insect and followed the population dynamics of both parasitoids and hosts during three years. Our results suggest an absence of Allee effects but clear negative density dependence instead: (1) the probability of establishment after three years was not affected by initial population size; (2) net reproductive rate was highest at low parasitoid density and high host density; (3) the sex ratio, reflecting the proportion of virgin females, did not increase at low density, suggesting that low densities did not impede mate-finding; (4) the depression of host populations did not depend upon the number of parasitoids introduced. This is, to our knowledge, the first experimental test of the Allee effect in an invading parasitoid. It leads us to propose that a number of behavioral and life-history features of many parasitoids could protect them from Allee effects. 相似文献