Affiner votre recherche
Résultats 681-690 de 1,324
Hollow fiber liquid-phase microextraction as clean-up step for the determination of organophosphorus pesticides residues in fish tissue by gas chromatography coupled with mass spectrometry Texte intégral
2011
Sun, Xiaojin | Zhu, Fang | Xi, Jiabin | Lu, Tongbu | Liu, Hong | Tong, Yexiang | Ouyang, Gangfeng
Hollow fiber liquid-phase microextraction (HF-LPME) technique was used as a clean-up procedure for the determination of organophosphorus pesticides (OPPs) in fish tissue. In this study, eight OPPs were first extracted with acetone from fish sample, the organic extract after rotatory evaporation was then redissolved with water–methanol (95:5, v/v) solution, followed by polyvinylidene difluoride (PVDF) HF-LPME. Experimental HF-LPME and other sample preparation conditions were carefully investigated and optimized. Under the optimum conditions, good linearity were observed in the range of 20–500ng/g, limits of detections (LODs) were in the range of 2.1–4.5ng/g. The repeatability and recovery of the method also showed satisfactory results. Compared with traditional sample preparation method for the determination of OPPs in fish tissue, the method developed in this study eliminated the solid phase extraction (SPE) step, simplified the sample preparation procedure and lowered the cost of analysis.
Afficher plus [+] Moins [-]Bioaccumulation of metals by Fucus ceranoides in estuaries of South West England Texte intégral
2011
Varmā, Raṇajīta | Turner, Andrew | Brown, M. T.
Fucus ceranoides tolerates abiotic conditions encountered across the full range of estuarine salinities. We examined the bioaccumulation of metals in individuals and metal concentrations in accompanying sediment samples collected at different locations along estuaries of South West England. Intra- and inter-estuarine variations in metal accumulation by F. ceranoides, after correction for particulate contamination using Fe as a proxy, were attributed to variations in the availabilities and concentrations of aqueous metals. Greatest accumulation was observed in estuaries that remain most heavily impacted by historical mining activities and for metals that were mobilised to the greatest extent during these operations (As, Cu, Sn, Zn). Arsenic concentrations displayed a seaward increase in estuaries in which multiple samples were taken, whereas Cd concentrations were always greatest in samples collected from the most landward locations. Ongoing research aims to better understand the mechanisms and kinetics of metal interactions with F. ceranoides and their dependence on salinity.
Afficher plus [+] Moins [-]Biological neutralization of chlor-alkali industry wastewater Texte intégral
2011
Jain, Rakeshkumar M. | Mody, Kalpana H. | Keshri, Jitendra | Jha, Bhavanath
The present work reports biological neutralization of chlor-alkali industrial effluent by an alkaliphilic bacterium, isolated from the Gujarat coast, which was identified as Enterococcus faecium strain R-5 on the basis of morphological, biochemical and partial 16S rRNA gene sequencing. The isolate was capable of bringing down the pH of waste water from 12.0 to 7.0 within 3h in the presence of carbon and nitrogen sources, with simultaneous reduction in total dissolved solutes (TDS) up to 19–22%. This bacterium produced carboxylic acid, as revealed by FT-IR analysis, which facilitated neutralization of alkaline effluent. The presence of unconventional raw materials viz. Madhuca indica flowers or sugar cane bagasse as carbon and nitrogen sources could effectively neutralize alkaline effluent and thus making the bioremediation process economically viable. The time required for neutralization varied with size of inoculum. To the best of our knowledge, this is the first report on biological neutralization of a chlor-alkali industrial effluent.
Afficher plus [+] Moins [-]The effectiveness of double hulls in reducing vessel-accident oil spillage Texte intégral
2011
Yip, Tsz Leung | Talley, Wayne Kenneth | Jin, Di
While much work has been done in investigating determinants of oil spillage attributed to vessel accidents, little research has been conducted on the effectiveness of ship hull design in reducing marine pollution. This paper addresses whether the double-hull requirement reduces vessel-accident oil spillage. The volume of oil spillage due to oil-cargo vessel accidents was investigated using tobit regressions and an empirical data set of individual vessel accident pollution incidents investigated by the US Coast Guard from 2001 to 2008. The results indicate that the double hull design on average reduces the size of oil spills by 20% and 62% in tank barge and tanker ship accidents, respectively.
Afficher plus [+] Moins [-]Enormous PCBs increase in oysters from the coast of Guangdong, China Texte intégral
2011
Gan, Ju-Li | Jia, Xiao-Ping | Jia, Ting | Lin, Qin | Cai, Wen-Gui
PCBs equivalent to Aroclor 1242 and 1254 in soft tissues of oysters Crassostrea rivularis from the Guangdong coast, China, were measured using a GC-ECD. PCB concentrations (ngg⁻¹d.w.) ranged from 30 to 2040 with an average of 315 in 2003–2007, and 0.35–1.43 with an average of 0.56 in 1989–1991. Annual averages were 0.61, 0.65, 313, 290 and 342ngg⁻¹, respectively in 1989, 1991, 2003, 2006 and 2007. In east Guangdong, the Pearl River Estuary, and west Guangdong, regional means were 444, 273, 194ngg⁻¹, respectively in 2003–2007, and 0.43, 0.78, 0.38ngg⁻¹, respectively in 1989–1991, indicating PCB levels in oysters have risen greatly by ratios of 350–1032 compared with earlier data. PCB sources may derive from older transformers, printing materials and pressworks. Fortunately, current residual PCBs in the oysters were 0.004–0.253mgkg⁻¹ (w.w.), still below hygienic criteria of China and developed countries.
Afficher plus [+] Moins [-]Monitoring of organic contaminants in sediments from the Korean coast: Spatial distribution and temporal trends (2001–2007) Texte intégral
2011
Choi, Hee Gu | Moon, Hyo Bang | Choi, Minkyu | Yu, Jun
Spatial and temporal trends of organic contaminants in sediments along the Korean coast were estimated through a nationwide environmental monitoring program from 2001 to 2007. The concentrations of organic contaminants in sediments along the Korean coast were relatively low or moderate compared with foreign studies. The mean detection frequencies of organic contaminants during the seven years were highest for PAHs and PCDD/Fs, followed by PCBs, DDTs, TBT and HCHs in decreasing order. Based on published sediment quality guidelines, the ecological risks of persistent organic pollutants in sediments along the Korean coast were low, despite exceedances of the ERL at 2–6 sites for DDTs, and the TEL at 9–18 sites for PCDD/Fs. Nonparametric tests to assess temporal trends revealed significant decreasing trends for PCBs and PCDD/Fs at four and three sites, respectively (p<0.05). These results reflect the effects of regulations on the use of those contaminants.
Afficher plus [+] Moins [-]Spatial analysis of the invasion of lionfish in the western Atlantic and Caribbean Texte intégral
2011
Johnston, Matthew W. | Purkis, Samuel J.
Pterois volitans and Pterois miles, two sub-species of lionfish, have become the first non-native, invasive marine fish established along the United States Atlantic coast and Caribbean. The route and timing of the invasion is poorly understood, however historical sightings and captures have been robustly documented since their introduction. Herein we analyze these records based on spatial location, dates of arrival, and prevailing physical factors at the capture sights. Using a cellular automata model, we examine the relationship between depth, salinity, temperature, and current, finding the latter as the most influential parameter for transport of lionfish to new areas. The model output is a synthetic validated reproduction of the lionfish invasion, upon which predictive simulations in other locations can be based. This predictive model is simple, highly adaptable, relies entirely on publicly available data, and is applicable to other species.
Afficher plus [+] Moins [-]Gilthead seabream (Sparus aurata) carrying antibiotic resistant enterococci. A potential bioindicator of marine contamination? Texte intégral
2011
Barros, Joana | Igrejas, Gilberto | Andrade, Margarida | Radhouani, Hajer | López, Maria | Torres, Carmen | Poeta, Patrícia
Antibiotic resistance in bacteria is a growing problem that is not only restricted to the clinical setting but also to other environments such as marine species that harbor antibiotic resistant bacteria and therefore may serve as reservoirs for antibiotic-resistance genetic determinants. The aim of this study was to evaluate antibiotic resistance phenotypes in enterococci isolated from fecal samples of gilthead seabream and the associated mechanisms of resistance. A collection of 118 samples were analyzed and 73 enterococci were recovered. The strains showed high percentages of resistance to erythromycin and tetracycline (58.9% and 17.8%, respectively). Lower level of resistance (<13%) was detected for quinupristin–dalfopristin, ampicillin, high-level-gentamicin, high-level-streptomycin, high-level-kanamycin, ciprofloxacin and chloramphenicol. The erm(B), tet(L) or tet(M), aac(6′)-aph(2″) and aph(3′)-IIIa genes were shown in isolates resistant to erythromycin, tetracycline, high-level gentamicin and high-level kanamycin, respectively. Antibiotic resistance in natural microbiota is becoming a concern of human and environmental health.
Afficher plus [+] Moins [-]Microbial water quality of the Georgian coastal zone of the Black Sea Texte intégral
2011
Janelidze, N. | Jaiani, E. | Lashkhi, N. | Tskhvediani, A. | Kokashvili, T. | Gvarishvili, T. | Jgenti, D. | Mikashavidze, E. | Diasamidze, R. | Narodny, S. | Obiso, R. | Whitehouse, C.A. | Huq, A. | Tediashvili, M.
From 2006 to 2008, microbial water quality was monitored along the Georgian coast of the Black Sea. Temperature, pH, salinity, and dissolved oxygen were measured, along with a variety of aquatic microbial parameters, including heterotrophic plate count (HPC), total culturable bacterial count (TCBC), and chlorophyll a (Chl-a) concentration. Total and fecal coliforms and total enterococci counts were recorded as indicators of fecal pollution. Vibrio bacteria, and Escherichia coli- and Vibrio-specific bacteriophages were isolated and enumerated to determine their relationships to standard marine pollution indicators. Persistent microbial pollution was observed, particularly in the summer months, with a higher rate of contamination in estuaries. Microbial indicators generally showed seasonal dependence, suggesting that temperature may influence bacterial dynamics in this environment. No correlation was apparent between fecal pollution indicators and physical–chemical and aquatic microbial parameters, although there were significant relationships amongst the indicators themselves, as well as with the prevalence of Vibrio bacteria and phage.
Afficher plus [+] Moins [-]A Bayesian network for analyzing biological acute and long-term impacts of an oil spill in the Gulf of Finland Texte intégral
2011
Lecklin, Tiina | Ryömä, Riitta | Kuikka, Sakari
Knowledge of oil-induced impacts from the literature and experts were used to develop a Bayesian network to evaluate the biological consequences of an oil accident in the low-saline Gulf of Finland (GOF). Analysis was carried out for selected groups of organisms. Subnetworks were divided into subgroups according to a predicted response to oil exposure. Two scenario analyses are presented: the most probable and the worst-case accident. The impact of the most probable accident in the GOF is rather small. In most of the groups studied oil-induced long-term effects are evaluated to be minor at least from the perspective of the whole GOF. After the worst-case accident negative effects are more likely. The model predicts that the most vulnerable groups are auks and ducks. Amphipods, gulls and to a lesser extend littoral fishes and seals may show delayed recovery after an accident. Also annual plant species may be susceptible to oil-induced disturbances.
Afficher plus [+] Moins [-]