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Результаты 681-690 из 2,503
Are fecal stanols suitable to record and identify a pulse of human fecal contamination in short-term exposed shellfish? A microcosm study
2014
Harrault, Loïc | Jardé, Emilie | Jeanneau, Laurent | Petitjean, Patrice
In this study, the capacity of oysters to bioaccumulate fecal stanols and to record a source-specific fingerprint was investigated by the short-term contamination of seawater microcosms containing oysters with a human effluent. Contaminated oysters bioaccumulated the typical fecal stanols coprostanol and 24-ethylcoprostanol and their bioaccumulation kinetics were similar to that of the Fecal Indicator Bacteria Escherichia coli used in European legislation. Although stanol fingerprints of contaminated water allowed the identification of the human specific fingerprint, this was not the case for oysters. This discrepancy is attributed to (i) high concentrations of endogenous cholestanol and sitostanol, responsible for “unbalanced” stanol fingerprints, (ii) different accumulation/depuration kinetics of fecal coprostanol and 24-ethylcoprostanol and (iii) the limits of the analytical pathway used. These results show that fecal stanols bioaccumulated by oysters are useful to record fecal contamination but the usefulness of stanol fingerprints to identify specific sources of contamination in shellfish currently seems limited.
Показать больше [+] Меньше [-]Distribution and transportation of polycyclic aromatic hydrocarbons (PAHs) at the Humen river mouth in the Pearl River delta and their influencing factors
2014
Liu, Feng | Yang, Qingshu | Hu, Yujie | Du, Huanhuan | Yuan, Fei
Five different water samples were collected from the surface to the bottom layers at the Humen river mouth in the Pearl River delta during the flood and ebb tides in August 2011, respectively. Changes in the distribution and characteristics of polycyclic aromatic hydrocarbons (PAHs) were examined to explore their transportation process. More than 62 types of PAHs were detected in the water columns. The mean concentration of the total PAHs ranged from 849.33 to 1370.53ng/l and from 629.21 to 2019.91ng/l during the flood and ebb tides, respectively. Furthermore, 2-ring PAHs were the most abundant species, followed by 3-ring PAHs. There were different composition patterns of the PAHs during the flood and ebb tides. And the transportation process of PAHs was influenced by their sources and different estuarine hydrodynamics. Analysis of the sources of the PAHs indicated that the PAHs were derived from primarily petroleum and coal combustion sources.
Показать больше [+] Меньше [-]XRF scanners as a quick screening tool for detecting toxic pollutant elements in sediments from Marín harbour in the Ría de Pontevedra (NW Spain)
2014
Rodríguez-Germade, I. | Rubio, B. | Rey, D.
X-ray fluorescence scanners, such as the Itrax™ Core Scanner (Itrax) (Cox Analytical Systems, Mölndal, Sweden), provide high-resolution geochemical data within several hours. However, the semi-quantitative nature of these analysers has hampered their use to study pollution. This study explores Itrax’s capabilities to detect trace metals, such as Hg and Cd, in the Ría de Pontevedra harbour (NW Spain). A set of Itrax detection levels were proposed for each metal after comparison with quantitative measurements obtained from Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Vapour Atomic Absorption Spectrometry (CVAAS) analyses. These quantitative data obtained after a sequential extraction were used to evaluate pollutant bioavailability and to determine metal pollution levels exhibiting Hg pollution. The reliability of inc/coh and Br/Cl ratios to assess the total organic matter variability was also evaluated. The results indicated that the Itrax is an efficient and fast option to monitor contamination, thereby avoiding laborious discrete analyses and reducing analytical cost and time.
Показать больше [+] Меньше [-]Compositions and constituents of freshwater dissolved organic matter isolated by reverse osmosis
2014
Zhang, Yulong | Huang, Wen | Ran, Yong | Mao, Jingdong
Dissolved organic matter (DOM) from riverine and lacustrine water was isolated using a reverse osmosis (RO) system. Solid-state 13C nuclear magnetic resonance (13C NMR) was used to quantitatively evaluate the compositions and constituents of DOM, which are compared with previous investigations on marine DOM. Results indicated that concentration factor (CF) was a key metric controlling yield and sorption of DOM on the RO system. The sorption was likely non-selective, based on the 13C NMR and δ13C analyses. Carbohydrates and lipids accounted for 25.0–41.5% and 30.2–46.3% of the identifiable DOM, followed by proteins (18.2–19.8%) and lignin (7.17–12.8%). The freshwater DOM contained much higher alkyl and aromatic C but lower alkoxyl and carboxyl C than marine DOM. The structural difference was not completely accounted for by using structure of high molecular weight (HMW) DOM, suggesting a size change involved in transformations of DOM during the transport from rivers to oceans.
Показать больше [+] Меньше [-]Monitoring 137Cs and 134Cs at marine coasts in Indonesia between 2011 and 2013
2014
Suseno, Heny | Prihatiningsih, Wahyu Retno
Environmental samples (seawater, sediments and biota) were collected along the eastern and western Indonesian coasts between 2011 and 2013 to anticipate the possible impacts of the Fukushima radioactive releases in Indonesia. On the eastern coasts (south and north Sulawesi), the 137Cs concentrations in the seawater and sediments were 0.12–0.32Bqm−3 and 0.10–1.03Bqkg−1, respectively. On the western coasts (West Sumatra, Bangka Island, North Java, South Java and Madura island), the 137Cs concentrations in the seawater and sediments were 0.12–0.66Bqm−3 and 0.19–1.64Bqkg−1, respectively. In general, the 137Cs concentrations in the fish from several Indonesian coasts were <MDA – 109.75mBqkg−1. In contrast, the 137Cs concentrations in mollusk, crab and prawn were 10.65–38.78, 4.02 and 6.16mBqkg−1, respectively. 134Cs was not detected in the seawater, sediments or biota. Thus, it was concluded that 137Cs on the eastern and western Indonesian coasts originated from global fallout.
Показать больше [+] Меньше [-]Spatial distribution of organic and pyritic sulfur in surface sediments of eutrophic Jiaozhou Bay, China: Clues to anthropogenic impacts
2014
Chen, Ke-Ke | Zhu, Mao-Xu | Yang, Gui-Peng | Fan, De-Jiang | Huang, Xiang-Li
Anthropogenic perturbations exert important impacts on sulfur geochemistry in marine sediments. In the study, chemical extraction was used to quantify four sulfur pools, i.e., pyrite, humic-acid sulfur (HA-S), fulvic-acid sulfur (FA-S), and residual organic sulfur (ROS), in surface sediments of eutrophic Jiaozhou Bay. Results show that riverine inputs are the main control on organic matter (OM) distribution in the sediments. OM enrichment in the eastern coast is mainly due to discharges of anthropogenic wastes. Spatial coupling of pyrite and FA-S vs. TOC points to the impacts of OM enrichment on formation and preservation of pyrite and FA-S. Poor spatial coupling of HA-S vs. TOC is due to low fractions of diagenetic OS in the pool. ROS is mainly from riverine inputs and anthropogenic OS has been superimposed on this pool. Spatial coupling among TOC, pyrite-S and FA-S is a sensitive indicator of anthropogenic impacts on benthic processes of the bay.
Показать больше [+] Меньше [-]The Mussel Watch California pilot study on contaminants of emerging concern (CECs): Synthesis and next steps
2014
Maruya, Keith A. | Dodder, Nathan G. | Weisberg, Stephen B. | Gregorio, Dominic | Bishop, Jonathan S. | Klosterhaus, Susan | Alvarez, David A. | Furlong, Edward T. | Bricker, Suzanne | Kimbrough, Kimani L. | Lauenstein, Gunnar G.
A multiagency pilot study on mussels (Mytilus spp.) collected at 68 stations in California revealed that 98% of targeted contaminants of emerging concern (CECs) were infrequently detectable at concentrations ⩽1ng/g. Selected chemicals found in commercial and consumer products were more frequently detected at mean concentrations up to 470ng/g dry wt. The number of CECs detected and their concentrations were greatest for stations categorized as urban or influenced by storm water discharge. Exposure to a broader suite of CECs was also characterized by passive sampling devices (PSDs), with estimated water concentrations of hydrophobic compounds correlated with Mytilus concentrations. The results underscore the need for focused CEC monitoring in coastal ecosystems and suggest that PSDs are complementary to bivalves in assessing water quality. Moreover, the partnership established among participating agencies led to increased spatial coverage, an expanded list of analytes and a more efficient use of available resources.
Показать больше [+] Меньше [-]Microbiological accumulation by the Mediterranean invasive alien species Branchiomma bairdi (Annelida, Sabellidae): Potential tool for bioremediation
2014
Stabili, Loredana | Licciano, Margherita | Lezzi, Marco | Giangrande, Adriana
We examined the bacterial accumulation and digestion in the alien polychaete Branchiomma bairdi. Microbiological analyses were performed on worm homogenates from “unstarved” and “starved” individuals and on seawater from the same sampling site (Ionian Sea, Italy). Densities of culturable heterotrophic bacteria (22°C), total culturable bacteria (37°C) and vibrios were measured on Marine Agar 2216, Plate Count Agar and TCBS Agar, respectively. Microbial pollution indicators were determined by the most probable number method. B. bairdi was able to accumulate all the six considered microbiological groups which, however, differ in their resistance to digestion. B. bairdi results more efficient than the other two co-occurring sabellids in removing bacteria suggesting that it may counteract the effects of microbial pollution playing a potential role for in situ bioremediation. Thus a potential risk, such as the invasion of an alien species, could be transformed into a benefit with high potential commercial gain and economic feasibility.
Показать больше [+] Меньше [-]Expansion of an invasive coral species over Abrolhos Bank, Southwestern Atlantic
2014
Costa, Thiago J.F. | Pinheiro, Hudson T. | Teixeira, João Batista | Mazzei, Eric F. | Bueno, Leonardo | Hora, Mike S.C. | Joyeux, Jean-Christophe | Carvalho Filho, Alfredo | Amado-Filho, Gilberto | Sampaio, Claudio L.S. | Rocha, Luiz A.
Invasive coral species of the genus Tubastraea have been increasingly recorded in Southwestern Atlantic waters since the 1980s. Their invasion and infestation are mainly related to port and oil exploration activities. For the first time the presence of Tubastraea tagusensis colonies is reported in Espírito Santo State, colonizing a port shore area, and incrusting oil/gas platform structures situated in the southern Abrolhos Bank, which is part of the most important coral reef system of the South Atlantic Ocean. Tubastraea colonies exhibit fast growth and high recruitment rates, and colonized 40% of the analyzed structures in just four years. The projection of port and oil/gas industry growth for the Espírito Santo State (more than 300%) highlights an alert to the dispersal of this alien species to natural areas.
Показать больше [+] Меньше [-]Physicochemical characteristics of PM2.5: Low, middle, and high–income group homes in Agra, India–a case study
2014
Singh, Pradyumn | Saini, Renuka | Taneja, Ajay
The present study shows the current scenario of the aggregate relation between income and pollution at the household level. The indoor sampling of fine particulate matter was conducted in low– middle– and high–income group homes in Agra City, the North Central region of India. The mean indoor concentrations of PM2.5 were 46.7μg/m3, 39.2μg/m3 and 25.6μg/m3 in low– middle– and high–income group homes respectively. The full–day variation revealed that the concentrations of fine particles were higher during morning and evening hours in all the three income group homes. The indoor meteorological parameters were also monitored. Using scanning electron microscopy coupled with energy dispersive x–ray spectrometer (SEM–EDS) chemical and elemental analysis of fine particles and their probable sources has been conducted in low– middle– high–income group homes. EDS spectra indicates the elemental composition of PM2.5 which can be distributed into following groups of particles i.e. C–O rich (54%), F rich (42%) and other (4%) in low–income group homes. In middle– and high–income group homes F rich (59–65%), C–O rich (32–37%) and other (3–4%) were observed in PM2.5. The SEM images of fine particles indicates that the particles are clustered into following groups i.e. aluminosilicates/silica particles, spherical carbon rich particles, nearly spherical fluorine rich particles, Mg–Si or Mg–Si–Al particles.
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