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Resultados 2171-2180 de 3,197
Identification of the sources of metal (lead) contamination in drinking waters in north-eastern Tasmania using lead isotopic compositions
2015
Harvey, P. J. | Handley, H. K. | Taylor, M. P.
This study utilises a range of scientific approaches, including lead isotopic compositions, to differentiate unknown sources of ongoing lead contamination of a drinking water supply in north-eastern Tasmania, Australia. Drinking water lead concentrations are elevated above the Australian Drinking Water Guideline (10 μg/L), reaching 540 μg/L in the supply network. Water lead isotopic compositions from the town of Pioneer (²⁰⁸Pb/²⁰⁷Pb 2.406, ²⁰⁶Pb/²⁰⁷Pb 1.144 to ²⁰⁸Pb/²⁰⁷Pb 2.360, ²⁰⁶Pb/²⁰⁷Pb 1.094) and Ringarooma (²⁰⁸Pb/²⁰⁷Pb 2.398, ²⁰⁶Pb/²⁰⁷Pb 1.117) are markedly different from the local bedrock (²⁰⁸Pb/²⁰⁷Pb 2.496, ²⁰⁶Pb/²⁰⁷Pb 1.237). The data show that the lead in the local waters is sourced from a combination of dilapidated drinking water infrastructure, including lead jointed pipelines, end-of-life polyvinyl chloride pipes and household plumbing. Drinking water is being inadvertently contaminated by aging infrastructure, and it is an issue that warrants investigation to limit the burden of disease from lead exposure.
Mostrar más [+] Menos [-]Prolonged starvation and subsequent recovery of nitrification process in a simulated photovoltaic aeration SBR
2015
Ma, Fangshu | Li, Anding | Li, Boyin | Cui, Zhibo | Shi, Chunhong | Zhou, Beihai
The ability of a new SBR (sequencing batch reactor) based on simulating photovoltaic aeration for maintaining nitrification activity under a 25-day starvation period was studied. The activity and abundance of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) and the diversity of AOB were investigated. The measured biomass decay rates were 0.017 day⁻¹ and 0.029 day⁻¹ for AOB and NOB, respectively. These decay rates correlated well with AOB and NOB population quantified by real-time PCR. The recovery of ammonia oxidation rate and nitrite oxidation rate needed 4 and 7 days, respectively, indicating that NOB was more affected than AOB by starvation conditions. According to the real-time PCR results, Nitrospira was the dominant NOB in the reactor. Phylogenetic analysis indicated that Nitrosomonas oligotropha cluster was the dominant major cluster before and after starvation. Moreover, Pareto-Lorenz evenness distribution curves were plotted to interpret the interspecies abundance of AOB; the results suggested that AOB community possessed a balanced structure with medium Fo (Functional organization). Thus, the community can potentially deal with changing environmental conditions (e.g., starvation) and preserve its functionality according to the concept of functional redundancy.
Mostrar más [+] Menos [-]Occurrence of selected pharmaceuticals in the principal sewage treatment plants in Rome (Italy) and in the receiving surface waters
2015
Patrolecco, Luisa | Capri, Silvio | Ademollo, Nicoletta
This paper provides data on the occurrence of selected human pharmaceuticals (carbamazepine, clofibric acid, diclofenac, fenofibrate, fenoprofen, gemfibrozil, ibuprofen, ketoprofen, and naproxen) including steroid hormones (17β-estradiol, 17α-ethinylestradiol, and estrone) in influents/effluents to/from the four principal wastewater treatment plants (WWTPs) serving the city of Rome (Italy), in two different sampling campaigns. Target compounds were also analyzed in the receiving River Tiber and River Aniene. Analytical determination was carried out by LC-MS/MS after sample cleanup and concentration by off-line solid-phase extraction (SPE). The aim of the study was to increase the information currently available on the presence and persistence of pharmaceuticals in Italian urban wastewaters and to evaluate the environmental impact of the pharmaceutical residues discharged through effluents into the receiving rivers. Results indicated that after the treatment processes, most of pharmaceuticals were not completely eliminated, as average removal efficiencies were in the 14–100 % wide range during both sampling periods, with higher yields in spring than in winter. Levels detected in overall samples ranged from 5 to 2,230 ng/L in influents and from 5 to 1,424 ng/L in effluents. Carbamazepine, diclofenac, ibuprofen, and gemfibrozil showed the highest persistence to removal. Concentrations in the receiving waters were about one order of magnitude lower than in effluents, with a tendency to increase progressively through the urban tract of the river. Finally, an environmental risk analysis showed that carbamazepine, gemfibrozil, and estrone can pose a high risk at the concentrations detected in effluents and a medium risk in rivers, highlighting their potential hazard for the health of the aquatic ecosystem.
Mostrar más [+] Menos [-]Exposures of zebrafish through diet to three environmentally relevant mixtures of PAHs produce behavioral disruptions in unexposed F1 and F2 descendant
2015
Vignet, Caroline | Joassard, Lucette | Lyphout, Laura | Guionnet, Tiphaine | Goubeau, Manon | Le Menach, Karyn | Brion, François | Kah, Olivier | Chung, Bon-Chu | Budzinski, Hélène | Bégout, Marie-Laure | Cousin, Xavier
The release of polycyclic aromatic hydrocarbons (PAHs) into the environment has increased very substantially over the last decades. PAHs are hydrophobic molecules which can accumulate in high concentrations in sediments acting then as major secondary sources. Fish contamination can occur through contact or residence nearby sediments or though dietary exposure. In this study, we analyzed certain physiological traits in unexposed fish (F1) issued from parents (F0) exposed through diet to three PAH mixtures at similar and environmentally relevant concentrations but differing in their compositions. For each mixture, no morphological differences were observed between concentrations. An increase in locomotor activity was observed in larvae issued from fish exposed to the highest concentration of a pyrolytic (PY) mixture. On the contrary, a decrease in locomotor activity was observed in larvae issued from heavy oil mixture (HO). In the case of the third mixture, light oil (LO), a reduction of the diurnal activity was observed during the setup of larval activity. Behavioral disruptions persisted in F1-PY juveniles and in their offspring (F2). Endocrine disruption was analyzed using cyp19a1b:GFP transgenic line and revealed disruptions in PY and LO offspring. Since no PAH metabolites were dosed in larvae, these findings suggest possible underlying mechanisms such as altered parental signaling molecule and/or hormone transferred in the gametes, eventually leading to early imprinting. Taken together, these results indicate that physiological disruptions are observed in offspring of fish exposed to PAH mixtures through diet.
Mostrar más [+] Menos [-]Estimates of pesticide concentrations and fluxes in two rivers of an extensive French multi-agricultural watershed: application of the passive sampling strategy
2015
Poulier, Gaëlle | Lissalde, Sophie | Charriau, Adeline | Buzier, Rémy | Cleries, Karine | Delmas, François | Mazzella, Nicolas | Guibaud, Gilles
In this study, the passive sampling strategy was evaluated for its ability to improve water quality monitoring in terms of concentrations and frequencies of quantification of pesticides, with a focus on flux calculation. Polar Organic Chemical Integrative Samplers (POCIS) were successively exposed and renewed at three sampling sites of an extensive French multi-agricultural watershed from January to September 2012. Grab water samples were recovered every 14 days during the same period and an automated sampler collected composite water samples from April to July 2012. Thirty-nine compounds (pesticides and metabolites) were analysed. DEA, diuron and atrazine (banned in France for many years) likely arrived via groundwater whereas dimethanamid, imidacloprid and acetochlor (all still in use) were probably transported via leaching. The comparison of the three sampling strategies showed that the POCIS offers lower detection limits, resulting in the quantification of trace levels of compounds (acetochlor, diuron and desethylatrazine (DEA)) that could not be measured in grab and composite water samples. As a consequence, the frequencies of occurrence were dramatically enhanced with the POCIS compared to spot sample data. Moreover, the integration of flood events led to a better temporal representation of the fluxes when calculated with the POCIS compared to the bimonthly grab sampling strategy. We conclude that the POCIS could be an advantageous alternative to spot sampling, offering better performance in terms of quantification limits and more representative data.
Mostrar más [+] Menos [-]Effects of algal bloom formation, outbreak, and extinction on heavy metal fractionation in the surficial sediments of Chaohu Lake
2015
Wang, Shu-guang | Diao, Xiao-jun | He, Lian-sheng
The effects of algal bloom (AB) on the physicochemical and biochemical properties of water and sediment in lakes have been widely studied. However, limited attention has been directed toward the effects of the processes of AB formation, outbreak, and extinction on heavy metal fractionation in sediment. In this study, water and sediment samples were collected from the AB and free algal bloom (FAB) regions of Chaohu Lake from May to September in 2012. The chemical fractionation of seven heavy metals (Cd, Cr, Cu, Mn, Ni, Fe, and Pb) in sediment was determined by using a modified three-step sequential procedure. Evident processes of AB formation, outbreak, and extinction were observed in the AB region, but not in the FAB region. The TN and TP concentrations in water and sediment in the AB region were significantly higher than those in the FAB region. The water DO concentration was higher in the AB region than that in the FAB region before the early stage of the AB outbreak, but an opposite trend was observed in the stages that followed. Metal fractionation in sediment showed that except for Mn and Cu, the majority of metals were in the residual fraction regardless of the AB process. The AB process slightly altered the concentrations of metal fractions, except for reducible Fe and oxidizable Cu. The result showed that AB formation, outbreak, and extinction slightly affected heavy metal fractionation in sediment though water properties were significantly different among AB processes.
Mostrar más [+] Menos [-]The three steps of the carbonate biogenic dissolution process by microborers in coral reefs (New Caledonia)
2015
Grange, J. S. | Rybarczyk, H. | Tribollet, A.
Biogenic dissolution of carbonates by microborers is one of the main destructive forces in coral reefs and is predicted to be enhanced by eutrophication and ocean acidification by 2100. The chlorophyte Ostreobium sp., the main agent of this process, has been reported to be one of the most responsive of all microboring species to those environmental factors. However, very little is known about its recruitment, how it develops over successions of microboring communities, and how that influences rates of biogenic dissolution. Thus, an experiment with dead coral blocks exposed to colonization by microborers was carried out on a reef in New Caledonia over a year period. Each month, a few blocks were collected to study microboring communities and the associated rates of biogenic dissolution. Our results showed a drastic shift in community species composition between the 4th and 5th months of exposure, i.e., pioneer communities dominated by large chlorophytes such as Phaeophila sp. were replaced by mature communities dominated by Ostreobium sp. Prior the 4th month of exposure, large chlorophytes were responsible for low rates of biogenic dissolution while during the community shift, rates increased exponentially (×10). After 6 months of exposure, rates slowed down and reached a “plateau” with a mean of 0.93 kg of CaCO₃ dissolved per m² of reef after 12 months of exposure. Here, we show that (a) Ostreobium sp. settled down in new dead substrates as soon as the 3rd month of exposure but dominated communities only after 5 months of exposure and (b) microbioerosion dynamics comprise three distinct steps which fully depend on community development stage and grazing pressure.
Mostrar más [+] Menos [-]Polychlorinated biphenyls and organochlorine pesticides in surface sediments from the sand flats of Shuangtaizi Estuary, China: levels, distribution, and possible sources
2015
Yuan, Xiutang | Yang, Xiaolong | Na, Guangshui | Zhang, Anguo | Mao, Yuze | Liu, Guize | Wang, Lili | Li, Xiaodong
Levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in sediments from the sandy flat system of Shuangtaizi Estuary, the highest-latitude estuary in China, were investigated to identify their possible sources and potential ecological risk. The concentrations of 28 PCBs and 18 OCPs ranged from 1.83 to 36.68 ng g⁻¹ dw (mean 10.53 ng g⁻¹ dw) and from 0.02 to 14.57 ng g⁻¹ dw (mean 5.65 ng g⁻¹ dw), respectively. Generally, these organic pollutants showed an obvious spatial distribution, and relatively high levels were found at the high-tidal zone near river mouths. Compositional analyses indicated that tetra-PCBs were dominant for PCBs, whereas heptachlor was identified to be prevalent for OCPs in surficial sediment in the sand flats of Shuangtaizi Estuary. Overall, Shuangtaizi Estuary had moderate PCB and OCP levels in the sand flat sediments and posed a low ecological hazard to aquatic biota. Our results indicated that the sediment PCBs came from nonpoint deposition, such as atmospheric contribution and river input, for light chlorinated congeners and point source deposition, such as the industrial sources along river flow, for highly chlorinated congeners, whereas OCPs originate mainly from old residuals and new usage of pesticides in agriculture and aquaculture.
Mostrar más [+] Menos [-]Removal of carbamazepine from spiked municipal wastewater using electro-Fenton process
2015
Komtchou, Simon | Dirany, Ahmad | Drogui, Patrick | Bermond, Alain
The electrochemical degradation of carbamazepine (CBZ) in both synthetic solutions (CBZo = 12 mg/L) and enriched municipal effluents (CBZo = 60–70 μg/L) was investigated using an electro-Fenton (EF) process. Different operating parameters were investigated, including current intensity, pH, reaction time, ferrous ion concentration, and the type of anode material. The current intensity, the type of anode material, and the concentration of ferrous ions played an important role in the CBZ degradation efficiency. The degradation was mainly attributed to direct anodic oxidation. The best operating conditions for the synthetic sample were obtained at a current density of 0.2 A, a pH of 3.0, and 120 min of treatment using a boron-doped diamond (BDD) anode in the presence of 0.25 mM of Fe²⁺. Under these conditions, 52 % of total organic carbon (TOC) and 73 % of CBZ were removed. The process was also tested as tertiary treatment for a municipal wastewater treatment plant effluent, and CBZ was completely removed.
Mostrar más [+] Menos [-]Ecophysiological and ultrastructural effects of dust pollution in lichens exposed around a cement plant (SW Slovakia)
2015
Paoli, Luca | Guttová, Anna | Grassi, Alice | Lackovičová, Anna | Senko, Dušan | Sorbo, Sergio | Basile, Adriana | Loppi, Stefano
The study investigated the ecophysiological and ultrastructural effects of dust pollution from a cement industry in the lichen species Evernia prunastri and Xanthoria parietina, which were exposed for 30, 90 and 180 days around a cement mill, two quarries, and inhabited and agricultural sites in SW Slovakia. The results showed that dust deposition from quarrying activities and cement works at the cement mill (mainly enriched in Ca, Fe and Ti) significantly affected the photosynthetic apparatus of E. prunastri (sensitive to dust and habitat eutrophication), while X. parietina (tolerant to dust and habitat eutrophication) adapted to the new environment. The length of the exposure strongly affected the vitality of the mycobiont (measured as dehydrogenase activity) in transplanted lichens. Dust deposition led to ultrastructural alterations, including lipid droplets increase, swelling of cellular components, thylakoid degeneration and sometimes plasmolysis, which, on the whole, gave the cells an aged appearance. Photosynthetic parameters deserve further attention as potential indicators for monitoring early biological symptoms of the air pollution caused during cement production.
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