Refinar búsqueda
Resultados 1651-1660 de 4,308
Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India Texto completo
2017
Nethaji, S. | Kalaivāṇan̲, Irāmanātan̲ | Arya Viswam, | Jayaprakash, M.
Surface sediments were collected from Vellar and Coleroon estuaries for determine sediment texture, calcium carbonate, organic matter and heavy metals. Pollution indices such as pollution load index (PLI), contamination factor (CF), enrichment factor (EF) and geo-accumulation index (Igeo) were done for this study to know the level of heavy metals pollution in the estuarine ecosystem. Pearson correlation matrix and factor were used to assess the relationship and source of heavy metals in the estuarine sediments. The results of PLI values reveal that the study area was polluted by all the heavy metals. The calculated values of CF and Igeo followed the decreasing order Cu>Ni>Pb>Co>Cr>Zn>Mn>Fe and illustrate that Cu, Ni and Pb are contaminated due to anthropogenic sources in both estuaries. Correlation and factor analysis suggest that FeMn oxyhydroxides, organic matter and fine particles are responsible for high concentration of heavy metals.
Mostrar más [+] Menos [-]Navigational threats by derelict fishing gear to navy ships in the Korean seas Texto completo
2017
Hong, Sunwook | Lee, Jongmyoung | Lim, Sehan
This study assessed the impact of derelict fishing gear (DFG) on navigation. The Republic of Korea's navy (ROKN) recorded every case of approximately 170 naval ships associated with propeller entanglement by DFG from January 2010 to December 2015. The frequency of cases was 2.3 per ship and 397.7 (±37.5) per year. The amount of DFG disentangled was 0.025tons per ship and 10.0 (±1.7) tons per year. The frequency temporally decreased whereas the amount increased over these six years. To disentangle propellers, 3.1 divers were needed on average per case. Propeller entanglement occurred in all local seas and some of these areas showed increases over time. Our study highlights that the impact of DFG on navigational threats has been persistent and ubiquitous and can potentially be reduced by preventing DFG in fishing areas, with a focus on improved management by fishermen and government and with more efficient retrieval of DFG.
Mostrar más [+] Menos [-]Modeling sampling strategies for determination of zooplankton abundance in ballast water Texto completo
2017
Hernandez, Marco R. | Johansson, Mattias L. | Xiao, Yanyu | Lewis, Mark A. | MacIsaac, Hugh J.
Ballast water has been a major source of non-indigenous species introductions. The International Maritime Organization has proposed performance standard that will establish an upper limit for viable organisms in discharged ballast. Here we test different sampling efforts for zooplankton in ballast water on a commercial vessel. We fit different probability density functions to find the most representative and evaluated sampling efforts necessary to achieve error rates (α, β) of <0.05. Our tests encompassed four seasonal trials and five sample volumes. To estimate error rates, we performed simulations which drew from 1 to 30 replicates of each volume (0.10–3.00m3) for mean densities ranging between 1 and 20 organisms m−3. Fieldwork and simulations suggested that >0.5m3 samples had the best accuracy and precision, and that the Poisson distribution fit these communities best. This study provides the first field test of a sampling strategy to assess compliance with the future IMO standard for large vessels.
Mostrar más [+] Menos [-]Biological effects of gold mine tailings on the intertidal marine environment in Nova Scotia, Canada Texto completo
2017
Doe, K. | Mroz, R. | Tay, K.-L. | Burley, J. | Teh, S. | Chen, S.
From 1861 to the 1940s, gold was produced from 64 mining districts in Nova Scotia, where mercury amalgamation was the dominant method for the extraction of gold from ore until the 1880s. As a result, wastes (tailings) from the milling process were contaminated by mercury and were high in naturally occurring arsenic. In 2004 and 2005, sediments, water and mollusc tissues were collected from 29 sampling stations at nine former gold mining areas along the Atlantic coastline and were analysed for arsenic and mercury. The resulting data were compared with environmental quality guidelines. Samples indicated high potential risk of adverse effects in the intertidal environments of Seal Harbour, Wine Harbour and Harrigan Cove. Arsenic in Seal Harbour was bioavailable, resulting in high concentrations of arsenic in soft-shell clam tissues. Mercury concentrations in tissues were below guidelines. This paper presents results of the sampling programs and implications of these findings.
Mostrar más [+] Menos [-]Methods comparison, transport and distribution of polar herbicides in the Baltic Sea Texto completo
2017
Skeff, Wael | Orlikowska, Anna | Schulz-Bull, Detlef E.
Two LC-MS/MS methods including different sample preparation and quantitative processes showed a good agreement for analysis of the herbicides MCPA, mecoprop, isoproturon, bentazon and chloridazon, and the metabolite chloridazon-methyl-desphenyl (CMD) in estuarine waters. Due to different sensitivity of the methods only one could be used to analyze marine samples. The transport of these compounds to the Baltic Sea via ten German estuaries and their distribution between coastal water and sediments was studied. The results showed that all selected compounds can be transported to the Baltic Sea (0.9–747ng/L). Chloridazon, bentazon, isoproturon and CMD were detected (0.9–8.9ng/L) in the coastal waters and chloridazon and isorproturon in the sediments (5–136pg/g d.w.). Levels of contaminants in the sediments could be influenced by the total organic carbon content. Concentrations observed in the Baltic Sea are most likely not high enough to cause acute effects, but long term effect studies are strongly recommended.
Mostrar más [+] Menos [-]Evaluation of hazardous airborne carbonyls in five urban roadside dwellings: A comprehensive indoor air assessment in Sri Lanka Texto completo
2017
Chan, Chi Sing | Ranasinghe, Ranasinghege Sampath Aravinda | Ho, Steven Sai Hang | Ho, Kin Fai | Yim, Steve Hung Lam | Sugathapala, A.G.T. | Lee, Shun Cheng | Hung, Wing Tat | Huang, Yu | Zhang, Hong
Indoor hazardous airborne carbonyls were quantified in five natural-ventilated roadside dwellings in Colombo, Sri Lanka. The total concentrations of all targeted carbonyls ranged from 13.6 to 18.6 μg/m3. Formaldehyde (C1) was the most abundant carbonyl, followed by acetaldehyde (C2) and acetone (C3K). The concentrations of C1 and C2 ranged from 3.3 to 8.5 μg/m3 and 2.3 to 4.4 μg/m3, respectively, which accounted for 23 to 42% and 18 to 26% respectively, to the total quantified carbonyls. The highest carbonyls levels were obtained in the dwelling located in an urban district with a mixture of industrial, commercial and residential areas. Much lower concentrations of carbonyls were measured in a light local traffic value was counted. Moderate correlations between individual combustion markers from vehicular emissions suggest the strong impacts from traffics to the indoor airs. The concentrations of C1 and C2 were compared with international indoor guidelines established by different authorities. A health assessment was conducted by estimation of inhalation cancer risk, implementing the inhalation unit risk values provided by Integrated Risk Information System (IRIS), associated with C1 and C2, which were 6.2 × 10−5 and 7.7 × 10−6, respectively. Even though the risks did not reach the action level (1 × 10−4), their health impact should not be overlooked. This kick-off indoor monitoring study provides valuable scientific data to the environmental science community since only limit data is available in Sri Lanka.
Mostrar más [+] Menos [-]Distribution and antimicrobial susceptibility of Vibrio species associated with zooplankton in coastal area of Korea Texto completo
2017
Yang, Ji Hye | Mok, Jong Soo | Jung, Yeoun Joong | Lee, Ka Jeong | Kwon, Ji Young | Park, Kunbawui | Moon, Seong Yong | Kwon, Soon Jae | Ryu, A Ra | Lee, Tea Seek
Vibrio parahaemolyticus and V. vulnificus are the most common pathogens causing seafood-borne illnesses in Korea. This study determines the abundance and antimicrobial resistance of pathogenic Vibrio species in seawater and zooplankton samples from the Geoje Island coast in Korea, which is an important area for coastal fisheries, the fishing industry, and tourism. The two Vibrio species were detected more in mesozooplankton samples than in seawater samples. V. parahaemolyticus isolates showed greater resistance than those of V. vulnificus for antimicrobials. Of V. parahaemolyticus isolates, 93.3% exhibited resistance to three or more antimicrobial agents. Conversely, more than 80% of V. vulnificus isolates showed susceptibility to all antimicrobials examined, with the exception of rifampicin. Our findings show that strong antimicrobial resistance of V. parahaemolyticus in the surveyed area was exposed to conventionally used antibiotics, therefore necessitating proper surveillance programs for the monitoring of antimicrobial resistance patterns in seawater bodies and aquatic animals.
Mostrar más [+] Menos [-]Combined membrane photocatalytic ozonation and wet absorption of elemental mercury Texto completo
2017
Huang, Z.S. | Wei, Z.S. | He, Y.M. | Pei, J.L. | Xiao, X.L. | Tang, M.R. | Yu, S.
Membrane photocatalytic ozonization coupled with wet absorption offers potential for elemental mercury (Hg0) removal. This study reports on a novel FeTiO2-coated polyvinylidene fluoride (PVDF) wet photocatalytic membrane reactor (WPCMR) for mercury removal in flue gas. Hg0 removal efficiency in the WPCMR reached up to 93.3%. Ozone could enhance mercury oxidation in WPCMR. Wet absorption helps to increases mercury removal efficiency. FeTiO2 catalyst was synthesized by sol-gel method and characterized by XRD, FTIR, UV–Vis, XPS and SEM. XPS analysis confirmed Hg0 oxidation to divalent mercury (Hg (II)). Elemental mercury was oxidized to mercuric oxide followed by wet absorption in the presence of OH free radical and ozone. Wet photocatalytic membrane reactor and photocatalytic membrane reactor (PCMR) of elemental mercury reaction with the FeTiO2/PVDF catalyst all follow Langmuir-Hinshelwood kinetics.
Mostrar más [+] Menos [-]The impact of wastewater treatment effluent on microbial biomasses and diversities in coastal sediment microcosms of Hangzhou Bay Texto completo
2017
Tao, Yile | Dai, Tianjiao | Huang, Bei | Wen, Donghui
Disposal of wastewater treatment plant (WWTP) effluent into sea, a typical anthropogenic disturbance, may influence many environmental factors and change the coastal microbial community structure. In this study, by setting up coastal sediment microcosms perturbed by WWTP effluent, the changes of microbial community structure under different degree of disturbances were investigated. Quantitative PCR (qPCR) and terminal restriction fragment length polymorphism (T-RFLP) were used to analyzed the biomass and biodiversity. High throughput sequencing analysis was used to identify the classification of the microorganisms. Our study suggested that low ratio of WWTP effluent may stimulate dominant species, which increase the biomass but decrease the biodiversity; while high ratio of WWTP effluent may depress all species, which decrease the biomass but increase the biodiversity. In other words, the impact was dose-dependent. The changes of microbial community structure may provide a metric for water environmental assessment and pollution control.
Mostrar más [+] Menos [-]Comparing different methods for fast screening of microbiological quality of beach sand aimed at rapid-response remediation Texto completo
2017
Testolin, Renan C. | Almeida, Tito C.M. | Polette, Marcus | Branco, Joaquim O. | Fischer, Larissa L. | Niero, Guilherme | Poyer-Radetski, Gabriel | Silva, Valéria C. | Somensi, Cleder A. | Corrêa, Albertina X.R. | Corrêa, Rogério | Rörig, Leonardo R. | Itokazu, Ana Gabriela | Férard, Jean-François | Cotelle, Sylvie | Radetski, Claudemir M.
There is scientific evidence that beach sands are a significant contributor to the pathogen load to which visitors are exposed. To develop beach quality guidelines all beach zones must be included in microbiological evaluations, but monitoring methods for beach sand quality are relatively longstanding, expensive, laborious and require moderate laboratory infrastructure. This paper aimed to evaluate the microorganism activity in different beach zones applying and comparing a classical method of membrane filtration (MF) with two colorimetric screening methods based on fluorescein (FDA) and tetrazolium (TTC) salt biotransformation to evaluate a new rapid and low-cost method for beach sand microbiological contamination assessments. The colorimetric results can help beach managers to evaluate rapidly and at low cost the microbiological quality of different beach zones in order to decide whether remedial actions need to be adopted to prevent exposure of the public to microbes due to beach sand and/or water contamination.
Mostrar más [+] Menos [-]