خيارات البحث
النتائج 1611 - 1620 من 4,241
Distribution and antimicrobial susceptibility of Vibrio species associated with zooplankton in coastal area of Korea
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.
اظهر المزيد [+] اقل [-]Comparing different methods for fast screening of microbiological quality of beach sand aimed at rapid-response remediation
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.
اظهر المزيد [+] اقل [-]Prediction of hourly ground-level PM2.5 concentrations 3 days in advance using neural networks with satellite data in eastern China
2017
Mao, Xi | Shen, Tao | Feng, Xiao
This study is an attempt to explore the effectiveness of satellite data in predicting hourly PM2.5 (Respirable particulate matter with aerodynamic diameter below 2.5 μm) concentrations for a chosen number of forward time steps over eastern China. MODIS (Moderate Resolution Imaging Spectroradiometer) aerosol optical depth (AOD), hourly forecasted meteorological variables, along with respective pollutant predictors from 2013 to 2015 were used as input to a multi-layer perceptron (MLP) type of back-propagation neural network. A novel approach, based on the correlation coefficients between surface PM2.5 and meteorological variables, was employed in selecting the averaging periods for meteorological input. Backward air mass trajectory was combined with AOD so as to explicitly measure the contribution of regional transport. Owing to the spatial variability of the AOD-PM2.5 relationship, each grid cell on the AOD retrievals was assigned to a prediction model trained by the nearest monitoring station from them. The proposed model seems to perform better in southern China. Also predictions incorporating transport predictor tend to have higher rates of detecting PM2.5 exceedance hours. We further introduced a sensitive analysis in Beijing by testing a model with surface PM2.5 input, evaluated versus the AOD input one. The two models were evaluated on the perturbed test set with input values ranging from 10 to 40%. It is found that PM model significantly outperforms the AOD one when the prediction horizon is longer than 36 h. This approach shows potential to be adapted for other regions, but will be most useful for areas without access to sophisticated deterministic models.
اظهر المزيد [+] اقل [-]Trends in wet precipitation, particulate, and gas-phase species in New York State
2017
Rattigan, O.V. | Civerolo, K.L. | Felton, H.D.
Here we characterized wet deposition National Atmospheric Deposition Program (NADP) species and Clean Air Status and Trends Network (CASTNET) dry deposited particle and gas species across New York over the last 2-3 decades. In addition measurements of NH3 from the Ammonia Monitoring Network (AMoN) were analyzed. In general decreasing annual trends are observed for wet deposition SO42− and NO3− species and dry deposited particle SO42−, NO3− and NH4+ as well as gas phase SO2 and HNO3 consistent with reductions in SO2 and NOx emissions. Wet deposited NH4+ however does not show consistent trends with most sites showing little trend across the region and an indication that levels at some sites maybe increasing. NH3 concentrations also appear to be increasing although the data record is only 8 years. Base cations, Ca2+ and Mg2+ show some decreases in the 1980s but concentrations are relatively uniform since the mid-1990s. Na+ and K+ show large year to year variations, by more than an order of magnitude for Na+ due to influence of marine air at a near coastal site. In general there was a balance between the sum of cations and the sum of anions earlier in the record but the tendency has been for a cation excess in the more recent 5–10 years. Understanding the deposition of reduced nitrogen species is likely to be of concern for the foreseeable future. Such data are important in understanding acidification recovery in response to emission controls.
اظهر المزيد [+] اقل [-]Effects of microplastics on sessile invertebrates in the eastern coast of Thailand: An approach to coastal zone conservation
2017
Thushari, Gajahin Gamage Nadeeka | Senevirathna, Jayan Duminda Mahesh | Yakupitiyage, Amararatne | Chavanich, Suchana
This study assessed the microplastic contamination of 3 most abundant sessile and intertidal invertebrates (Rock Oyster: Saccostrea forskalii, Striped Barnacle: Balanus amphitrite, Periwinkle: Littoraria sp.) in 3 beaches of the eastern coasts of Thailand. The results showed a significant accumulation of microplastics in the invertebrates at rates of 0.2–0.6 counts/g indicating higher pollution levels along the coastline. Filter feeding organisms showed comparatively higher accumulation rates of microplastics. Thus, contaminated bivalves pose potential health risks for seafood consumers. The plastic pollutant prevalence in sessile and intertidal communities was corresponded with pollution characteristics of contaminated beach habitats where they live. Thus, bivalves, gastropods and barnacles can be used as indicators for contamination of microplastics in the areas. This study also demonstrated the need for controlling plastic pollution in Thai coastal areas.
اظهر المزيد [+] اقل [-]Seasonal influence of scallop culture on nutrient flux, bacterial pathogens and bacterioplankton diversity across estuaries off the Bohai Sea Coast of Northern China
2017
He, Yaodong | Sen, Biswarup | Shang, Junyang | He, Yike | Xie, Ningdong | Zhang, Yongfeng | Zhang, Jianle | Johnson, Zackary I. | Wang, Guangyi
In this study, we investigated the environmental impacts of scallop culture on two coastal estuaries adjacent the Bohai Sea including developing a quantitative PCR assay to assess the abundance of the bacterial pathogens Escherichia coli and Vibrio parahaemolyticus. Scallop culture resulted in a significant reduction of nitrogen, Chlorophyll a, and phosphorous levels in seawater during summer. The abundance of bacteria including V. parahaemolyticus varied significantly across estuaries and breeding seasons and was influenced by nitrate as well as nutrient ratios (Si/DIN, N/P). Bacterioplankton diversity varied across the two estuaries and seasons, and was dominated by Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes. Overall, this study suggests a significant influence of scallop culture on the ecology of adjacent estuaries and offers a sensitive tool for monitoring scallop contamination.
اظهر المزيد [+] اقل [-]Evaluating trace element bioavailability and potential transfer into marine food chains using immobilised diatom model species Phaeodactylum tricornutum, on King George Island, Antarctica
2017
Cabrita, Maria Teresa | Padeiro, Ana | Amaro, Eduardo | dos Santos, Margarida Correia | Leppe, Marcelo | Verkulich, Sergey | Hughes, Kevin A. | Peter, H. U. (Hans-Ulrich) | Canário, João
In order to evaluate trace element bioavailability and potential transfer into marine food chains in human impacted areas of the Fildes Peninsula (King George Island, South Shetland Islands Archipelago), element levels (Cr, Ni, Cu, Zn, Cd, and Pb) were determined in water, sediments, phytoplankton, and in diatom Phaeodactylum tricornutum Bohlin (Bacillariophyceae) cells immobilised in alginate and exposed to water and sediments, from the Bellingshausen Dome (reference site) and Ardley Cove (human impacted area), during January 2014. High element concentrations in exposed P. tricornutum indicated element mobilisation from sediments into the water. Levels in exposed cells reflected the sediment element content pattern, comparable to those found in phytoplankton, supporting phytoplankton as an important path of trace element entry into marine food chains. This study clearly shows immobilised P. tricornutum as good proxy of phytoplankton concerning element accumulation efficiency, and an effective tool to monitor trace element contamination in polar coastal ecosystems.
اظهر المزيد [+] اقل [-]Evaluation of hazardous airborne carbonyls in five urban roadside dwellings: A comprehensive indoor air assessment in Sri Lanka
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.
اظهر المزيد [+] اقل [-]Application of computational intelligence techniques to forecast daily PM10 exceedances in Brunei Darussalam
2017
Dotse, Sam-Quarcoo | Petra, Mohammad Iskandar | Dagar, Lalit | De Silva, Liyanage C.
Particulate matter (PM10) is the pollutant causing exceedances of ambient air quality thresholds, and the key indicator of air quality index in Brunei Darussalam for haze related episodes caused by the recurrent biomass fires in Southeast Asia. The present study aims at providing suitable forecasts for PM10 exceedances to aid in health advisory during haze episodes at the four administrative districts of the country. A framework based on random forests (RFs), genetic algorithm (GA) and back propagation neural networks (BPNN) computational intelligence techniques has been proposed in which the final prediction is made by the BPNN model. A hybrid combination of GA and RFs is initially applied to determine optimal set of inputs from the initial data sets of largely available meteorological, persistency of high pollution levels, short and long term variations of emissions rates parameters. The inputs selection procedure does not depend on the back propagation training algorithm. The numerical results presented in this paper show that the proposed model not only produced satisfactory forecasts but also consistently performed better via several statistical performance indicators when compared with the standard BPNN and GA optimisation based on back propagation training algorithm. The model also showed satisfactory threshold exceedances forecasts achieving for instance best true predicted rate of 0.800, false positive rate of 0.014, false alarm rate of 0.333 and success index of 0.786 at Brunei-Muara district monitoring station. Overall, the current study has profound implications on future studies to develop a real-time air quality forecasting system to support haze management.
اظهر المزيد [+] اقل [-]Anthropogenic (PBDE) and naturally-produced (MeO-PBDE) brominated compound levels in Bizerte Lagoon clams (Ruditapes decussatus): Levels and human health risk assessment
2017
El Megdiche, Yassine | Ameur, Walid Ben | Bèchir, Hammami | Hassine, Sihem Ben | Badreddine, Barhoumi | Touil, Soufiane | Driss, Mohamed Ridha | Eljarrat, Ethel | Barceló, Damià
Information on the occurrence of organobrominated compounds in bivalves from Tunisia is scarce. To the best of our knowledge, this is the first report of these compounds in clams from Tunisia. The aim of this study is to measure natural and synthetic organobrominated compound concentrations and evaluate congener distribution and pollution sources in a clam species (Ruditapes decussatus) from three sites of the Bizerte Lagoon. Total synthetic organobrominated pollutant levels in clam ranged from 34.8 to 188ngg−1lw. For natural organobrominated compounds, concentrations varied from 18.2 to 49.5ngg−1lw. Total PBDE and MeO-PBDE concentrations in clams from the Bizerte Lagoon were similar or slightly lower than those reported for other species from other locations around the world. The health risks associated with the consumption of this species were assessed and posed no threat to public health concerning PBDE intakes.
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