خيارات البحث
النتائج 751 - 760 من 2,512
Status of trace metals in surface seawater of the Gulf of Aqaba, Saudi Arabia النص الكامل
2014
Al-Taani, Ahmed A. | Batayneh, Awni | Nazzal, Yousef | Ghrefat, Habes | Elawadi, Eslam | Zaman, Haider
The Gulf of Aqaba (GoA) is of significant ecological value with unique ecosystems that host one of the most diverse coral communities in the world. However, these marine environments and biodiversity have been threatened by growing human activities. We investigated the levels and distributions of trace metals in surface seawater across the eastern coast of the Saudi GoA. Zn, Cu, Fe, B and Se in addition to total dissolved solids and seawater temperature exhibited decreasing trends northwards. While Mn, Cd, As and Pb showed higher average levels in the northern GoA. Metal input in waters is dependent on the adjacent geologic materials. The spatial variability of metals in water is also related to wave action, prevailing wind direction, and atmospheric dry deposition from adjacent arid lands. Also, water discharged from thermal desalination plants, mineral dust from fertilizer and cement factories are potential contributors of metals to seawater water, particularly, in the northern GoA.
اظهر المزيد [+] اقل [-]Airborne molds and mycotoxins in Serpula lacrymans–damaged homes النص الكامل
2014
Pottier, Didier | André, Véronique | Rioult, Jean–Philippe | Bourreau, Alain | Duhamel, Chantal | Bouchart, Valerie Kientz | Richard, Estelle | Guibert, Mathieu | Verite, Philippe | Garon, David
For some years, the degradation of homes by the dry rot fungus Serpula lacrymans increased. This study described, for the first time, the fungal contamination in homes located in Low–Normandy (France) and damaged by Serpula lacrymans. Wood–decaying fungi, airborne molds, fungal species growing on building materials were investigated by cultural and molecular methods. Mycotoxins in the air were quantified by HPLC–MS/MS and the mutagenicity of fungal aerosols was also evaluated using the Ames test. The results showed that Serpula lacrymans was detected in the air for one third of homes with sometimes the co–occurrence of other ligninolytic basidiomycetes species like Donkioporia expansa. Various molds in the air and on materials (117 and 103 species, respectively) were also identified indicating the complexity of indoor mycoflora. Certain recurrent species like Aspergillus versicolor and Penicillium fellutanum were observed both on building materials and in the air. The presence of cellulolytic molds in fungal aerosols and on building materials could be used as an indicator of home degradation. Airborne culturable fungal levels were measured up to 5.8x105 Colony Forming Units (CFU) per cubic meter of the air (CFU/m3) depending on the home. Fungal concentrations also depended on the type of collector (filter or liquid) and were significantly correlated with the median of particles between 2–15μm in size. Two mycotoxins (alternariol and/or ochratoxin A) were observed in 4 homes but no mutagenic activity was found.
اظهر المزيد [+] اقل [-]Sulfur dioxide exposure and environmental justice: a multi–scale and source–specific perspective النص الكامل
2014
Zou, Bin | Peng, Fen | Wan, Neng | Wilson, JGaines | Xiong, Ying
Recent studies examining racial and ethnic inequities in exposure to urban air pollution have led to advances in understanding the nature and extent of overall concentration exposures by pollutant, demarcated by disadvantaged groups. However, the stability of inequities at various spatial units and the exposure by air pollution sources are often neglected. In this case study from the Dallas–Fort Worth (Texas, USA) area, we used Geographic Information Systems (GIS) and an air dispersion model to estimate environmental justice impacts at different spatial scales (i.e., zip code, census tract, block group) and by source (i.e., industrial pollution sources, vehicle pollution sources, industry and vehicle pollution sources combined). Using whites as a reference, blacks and other races were more likely to be exposed to higher sulfur dioxide (SO2) concentrations although the Odds Ratio (OR) varied substantially by pollution source type [e.g., industrial pollution source based: (OR=1.80; 95% CI (Confidence Interval): 1.79–1.80) vs. vehicle pollution source based: (OR=2.70; 95% CI: 2.68–2.71)] and varied less between spatial scales [for vehicle pollution sources, (OR=2.70; 95% CI: 2.68–2.71) at the census tract level but was (OR=2.54; 95% CI: 2.53–2.55) at the block group scale]. Similar to the pattern of racial inequities, people with less education (i.e., less than 12 years of education) and low income (i.e., per capital income below $20 000) were more likely to be exposed to higher SO2 concentrations, and those ORs also varied greatly with the pollution sources and slightly with spatial scales. It is concluded that the type of pollution source plays an important role in SO2 pollution exposure inequity assessment, while spatial scale variations have limited influence. Future studies should incorporate source–specific exposure assessments when conducting studies on environmental justice.
اظهر المزيد [+] اقل [-]Use of passive samplers for improving oil toxicity and spill effects assessment النص الكامل
2014
Letinski, Daniel | Parkerton, Thomas | Redman, Aaron | Manning, Ryan | Bragin, Gail | Febbo, Eric | Palandro, David | Nedwed, Tim
Methods that quantify dissolved hydrocarbons are needed to link oil exposures to toxicity. Solid phase microextraction (SPME) fibers can serve this purpose. If fibers are equilibrated with oiled water, dissolved hydrocarbons partition to and are concentrated on the fiber. The absorbed concentration (Cpolymer) can be quantified by thermal desorption using GC/FID. Further, given that the site of toxic action is hypothesized as biota lipid and partitioning of hydrocarbons to lipid and fibers is well correlated, Cpolymer is hypothesized to be a surrogate for toxicity prediction. To test this method, toxicity data for physically and chemically dispersed oils were generated for shrimp, Americamysis bahia, and compared to test exposures characterized by Cpolymer. Results indicated that Cpolymer reliably predicted toxicity across oils and dispersions. To illustrate field application, SPME results are reported for oil spills at the Ohmsett facility. SPME fibers provide a practical tool to improve characterization of oil exposures and predict effects in future lab and field studies.
اظهر المزيد [+] اقل [-]In situ detrimental impacts of Prorocentrum donghaiense blooms on zooplankton in the East China Sea النص الكامل
2014
Lin, Jia-Ning | Yan, Tian | Zhang, Qing-Chun | Wang, Yunfeng | Liu, Qing | Zhou, Ming-Jiang
Large-scale algal blooms of the dinoflagellate Prorocentrum donghaiense have occurred frequently in the East China Sea (ECS) in recent decades. However, its impacts on the zooplankton in situ are still under not well understood. During a spring P. donghaiense bloom (April–May 2013) along the northern coast of Fujian Province (120°–121°30″E, 26°30″–28°N), we found that the bloom decreased the abundance of copepods and had no significant effect on chaetognaths and small jellyfish. However, the abundance of small jellyfish increased over the course of the study. The zooplankton community changed from being copepod and small jellyfish- to small jellyfish-dominated during the bloom. In the bloom areas, the copepod Calanus sinicus showed higher mortality and lower egg production rates (EPR) than those in the non-bloom areas. The results suggested that P. donghaiense blooms had detrimental effects on the structure of zooplankton community and the recruitments of C. sinicus.
اظهر المزيد [+] اقل [-]New methodology for analysing and increasing the cost-efficiency of environmental monitoring networks النص الكامل
2014
Abramic, Andrej | Martínez-Alzamora, Nieves | González del Rio Rams, Julio | Barrachina, Teresa | Ferrer Polo, José
This study focuses on the coastal monitoring network established in the scope of WFD implementation. The objective of this network was to provide an ecological assessment of Valencian coastal waters. After three years, sufficient data had been collected to enable us to analyse and explore ways to increase the network’s efficiency.A methodology was developed to select the best subset of sampling stations to be surveyed. This method was approached from the perspective of an inter-observer variability problem. In order to compare the concordance between the k-observers and the reference observer, two measures were considered: euclidean distance, and interclass correlation coefficient.The obtained results confirm that the current network can be reduced by over 50% and still guarantee accurate results. This methodology (not limited by indicators, geographically, or by type of water body) could be applied to different environmental monitoring networks and could significantly decrease the efforts and costs required by the WFD.
اظهر المزيد [+] اقل [-]The Mussel Watch California pilot study on contaminants of emerging concern (CECs): Synthesis and next steps النص الكامل
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.
اظهر المزيد [+] اقل [-]Effects of ship emissions on summertime aerosols at Ny–Alesund in the Arctic النص الكامل
2014
Zhan, Jianqiong | Gao, Yuan | Li, Wei | Chen, Liqi | Lin, Hongmei | Lin, Qi
Selected trace elements, ionic species and organic/elemental carbon in aerosols were measured in summer at Ny–Alesund in the Arctic, and an interpreted approach combining elemental ratios, back–trajectories and enrichment factors was used to assess the sources of aerosols observed at this location. Aerosol samples influenced by ship emissions were featured by elevated concentrations of non–crustal (nc) vanadium (V), nc–nickel (nc–Ni), non–sea salt (nss) sulfate (SO42−) and ratios of nc–Ni/nc–V (1.7) and nss–SO42−/nc–V (200). When two cruise ships with more than 1 500 passengers visited Ny–Alesund in July 2012, the total suspended particulate (TSP) mass reached 2 290ng m−3, almost three times the median TSP concentration (609ng m−3) measured during the study period. The nc–V concentration reached 0.976ng m−3, about 38–fold higher compared to the mean value of the sampling period, and this value was even higher than the annual mean value observed at Zeppelin station and the values measured during Haze events at North American Arctic and Norwegian Arctic. The concentrations of nc–Ni and nss–SO42− were 0.572ng m−3 and 203ng m−3, which were 8–fold and 2–fold higher than the median values of the sampling period. While in the few–ship period, defined as the period with none or only one cruise ship with less than 1 000 passengers being present, aerosols at this location could be affected by a mixed impact of local emissions and long–range transport, reflected by the nc–Mn/nc–V ratios and element enrichment factors often found in the air masses from North America Arctic, Iceland and North Eurasia. Results from this study suggest that cruise ship emissions contributed significantly to atmospheric particulate matter at Ny–Alesund in the summer, effecting air quality in this area.
اظهر المزيد [+] اقل [-]Effects of the modified Huanglian Jiedu decoction on the disease resistance in grey mullet (Mugil cephalus) to Lactococcus garvieae النص الكامل
2014
Choi, W.M. | Lam, C.L. | Mo, W.Y. | Cheng, Z. | Mak, N.K. | Bian, Z.X. | Wong, M.H.
Lactococcosis is prevalent on grey mullet (Mugil cephalus) in Hong Kong aquaculture resulting in serious economic loss. A compound formulation of Traditional Chinese Medicines (TCM) (modified Huanglian Jiedu decoction (HLJDD)) comprising Rhizoma coptidis, Radix scutellaria, Cortex phellodendri, Fructus gardeniae, Fructus forsythiae and Flos lonicerae japonicae (in a ratio of 3:2:2:3:3:5) were applied as feed supplements to deal with the disease. The Nitroblue tetrazolium activity in blood, bactericidal activity and total immunoglobulin in plasma were significantly enhanced after feeding 1% of this TCM for 28days. The disease resistances to Lactococcus garvieae in 1% and 2% TCM feeding groups were significantly enhanced. In the in vitro study, the modified HLJDD also activated the plasma bactericidal activities (p<0.01). Based on this study, 1% modified HLJDD feeding for 28days may be an optimal dose to prevent L. garvieae infection and could be used in aquaculture industries.
اظهر المزيد [+] اقل [-]Origin, patterns and anthropogenic accumulation of potentially toxic elements (PTEs) in surface sediments of the Avilés estuary (Asturias, northern Spain) النص الكامل
2014
Sierra, C. | Boado, C. | Saavedra, A. | Ordóñez, C. | Gallego, J.R.
Sediment quality has been assessed within the Avilés estuary, an important industrial area in the NW of Spain. The study started with a geochemical characterization of the superficial sediments that revealed some anomalous metal(oid)s concentrations in sensitive areas such as beaches or dunes. These data were studied by means of multivariate statistical techniques and enrichment factors calculation to evaluate the correlations and geochemical origin within the different elements. A novel approach using the combination of enrichment factors with a sequential application of factor analysis, clustering and kriging was essential to identify the possible sources of pollution. The collected information suggested that Cd (strongly correlated with Zn and Pb) was the potentially toxic element most widely distributed and problematic. Furthermore, particulate emissions from Zn metallurgy, as well as dust generated by the mineral loading and stockpile activities in the port were identified as the most important sources of pollution.
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