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Resultados 1221-1230 de 4,309
Seasonal and spatial variations of marine litter on the south-eastern Black Sea coast Texto completo
2017
Terzi, Yahya | Seyhan, Kadir
The south-eastern Black Sea coast in Turkey was evaluated for marine litter composition and density covering nine beaches during four seasons. The marine litter (>2cm in size), was collected from the coast and categorized into material and usage categories. The data analysis showed that plastic was the most abundant litter (≥61.65%) by count and weight followed by styrofoam and fabric. The marine litter density ranged from 0.03 to 0.58 with a mean (±SD) of 0.16±0.02 items/m2 by count. Based on weight, it varied between 0.44 and 14.74g/m2 with 3.35±1.63. The east side had a higher marine litter density than the west side with significant differences between beaches. The variations due to different seasons were not significant for any beach. The results of this study should provide baseline information about the coastal marine pollution and will assist the mitigation strategies.
Mostrar más [+] Menos [-]A Recent Overview of Palm Oil Mill Effluent Management via Bioreactor Configurations Texto completo
2017
Rana, Supriyanka | Singh, Lakhveer | Wahid, Zularisam | Liu, Hong
Worldwide, crude palm oil industries generate an overwhelming amount of palm oil mill effluent (POME). Since the past few decades, environmental issues associated with POME disposal have challenged the palm oil-producing nations which led them to reevaluate and develop their waste management strategies by using advanced biotreatment technologies. With the help of these technological advances, POME has emerged as a valuable biomass resource with great potential to produce sustainable renewable resources like biogas. This review entails various POME treatment methods in vogue and offers an insight into their improved applicability potential and pollution mitigation strategies by using proposed improved configurations like ponding system, open digesting tanks, anaerobic digestion based-bioreactors, aerobic anaerobic hybrid bioreactors, and membrane bioreactors. This review paper also gives an overview about the recent advancements in POME treatment bioreactor configurations and emphasizing their scope in large-scale applications on an industrial level. This review also critically analyzes their performance level to achieve the standard POME discharge limit by efficiently removing high COD (chemical oxygen demand), BOD (biological oxygen demand), and TSS (total suspended solid).
Mostrar más [+] Menos [-]Storms do not alter long-term watershed development influences on coastal water quality Texto completo
2017
Chen, Yushun | Cebrian, Just | Lehrter, John | Christiaen, Bart | Stutes, Jason | Goff, Josh
A twelve year (2000−2011) study of three coastal lagoons in the Gulf of Mexico was conducted to assess the impacts of local watershed development and tropical storms on water quality. The lagoons have similar physical and hydrological characteristics, but differ substantially in the degree of watershed urban development and nutrient loading rates. In total the lagoons experienced 22 storm events during the period studied. Specifically, we examine (1) whether there are influences on water quality in the lagoons from watershed development, (2) whether there are influences on water quality in the lagoons from storm activity, and (3) whether water quality is affected to a greater degree by watershed development versus storm activity. The two urbanized lagoons typically showed higher water-column nitrate, dissolved organic nitrogen, and phosphate compared with the non-urbanized lagoon. One of the urbanized lagoons had higher water-column chlorophyll a concentrations than the other two lagoons on most sampling dates, and higher light extinction coefficients on some sampling dates. The non-urbanized lagoon had higher water-column dissolved oxygen concentrations than other lagoons on many sampling dates. Our results suggest long-term influences of watershed development on coastal water quality. We also found some evidence of significant storm effects on water quality, such as increased nitrate, phosphate, and dissolved oxygen, and decreased salinity and water temperature. However, the influences of watershed development on water quality were greater. These results suggest that changes in water quality induced by human watershed development pervade despite the storm effects. These findings may be useful for environmental management since they suggest that storms do not profoundly alter long-term changes in water quality that resulted from human development of watersheds.
Mostrar más [+] Menos [-]The measurement of bisphenol A and its analogues, perfluorinated compounds in twenty species of freshwater and marine fishes, a time-trend comparison and human health based assessment Texto completo
2017
Wong, Y.M. | Li, R. | Lee, C.K.F. | Wan, H.T. | Wong, Chris K.C.
Our previous study in 2011 reported the detection of BPA and PFAAs in 20 species of marine and freshwater fishes. With an emerging evidence to suggest the metabolic-disrupting effects of BPA/PFAAs in animals, the present study was aimed to provide a time-trend analysis to determine the current concentrations of PFAAs and BPA in 20 commercially available Hong Kong species of fishes. Since the manufacture and use of BPA is being prohibited in most nations, the introduction of BPA alternatives has recently been incorporated in the markets. Therefore, the concentrations of BPB, BPF and BPS were determined. In the present study, all freshwater and seawater fish samples showed quantified concentrations [>Limit of Quantification (LOQ<0.5ng/g)] of BPA. BPF was detected in some marine (yellow seafin, bigeye, goldspotted rabbitfish, snubnose pompano, tongue sole, Bleeker's grouper and orange-spotted grouper) and freshwater fishes (mud carp, crucian carp, tilapia, catfish, mandarin fish, grass carp, grey mullet and spotted snakehead). Two of the compounds, BPS and BPB could only be identified in the marine fishes (snubnose pompano, yellow seafin). In PFAA analysis, PFOA, PFDA, PFOS, PFUdA and PFDoA were found in most of the marine and freshwater fishes. PFOS and PFOA were shown to be the two predominant PFAAs in fishes. On the basis of the measured concentrations of bisphenols, BPs (BPA, BPB, BPF, BPS) and PFAAs, the average daily intake for BPs (20.5–31.5ng/kgb.w./day) and PFAAs (1.17–1.83ng/kgb.w./day) were calculated and found to be lower than values of tolerable daily intake (TDI) established in Europe. However, as compared with our previous study in 2011, the present study revealed an approximate 10-fold increase in the concentrations of BPA in the fish samples. Although the hazard ratio of consuming fishes for BPA and PFAA exposure is expected to remain low, possible additive metabolic-disrupting effect of BPA and its analogues as well PFAAs should be taken into consideration for human health risk assessment.
Mostrar más [+] Menos [-]Ethylene source attribution modeling in the Greater Houston area Texto completo
2017
McNally, Dennis | Stella, Gregory | Loomis, Cynthia
Ethylene is a ubiquitous industrial gas that is emitted by a wide variety of biogenic, biomass burning, and anthropogenic sources, so the opportunity for human exposure is widespread. We believe that a comprehensive exposure assessment of ethylene from emissions sources has not specifically been evaluated so this study was conducted to estimate the relative contribution of different sources on atmospheric concentrations in the Greater Houston area.Source attribution modeling shows that when averaged over the full modeling domain, inclusive of industrial, urban, rural and water areas, ethylene concentrations are dominated by natural source emissions (fires and biogenic) with an annual mean of 69% of total ethylene concentration. Of the anthropogenic sources, which account for the remaining 31% of the annual ethylene concentration, the largest contribution was from area/non-road sources (annual mean of 16%) with industrial source (annual mean of 11%) and on-road motor vehicle (annual mean of 4%) sources showing relatively lower concentration contributions.
Mostrar más [+] Menos [-]Degradation pathways of 1-methylphenanthrene in bacterial Sphingobium sp. MP9-4 isolated from petroleum-contaminated soil Texto completo
2017
Zhong, Jianan | Luo, Lijuan | Chen, Baowei | Sha, Sha | Qing, Qing | Tam, Nora F.Y. | Zhang, Yong | Luan, Tiangang
Alkylated polycyclic aromatic hydrocarbons (PAHs) are abundant in petroleum, and alkylated phenanthrenes are considered as the primary PAHs during some oil spill events. Bacterial strain of Sphingobium sp. MP9-4, isolated from petroleum-contaminated soil, was efficient to degrade 1-methylphenanthrene (1-MP). A detailed metabolism map of 1-MP in this strain was delineated based on analysis of metabolites with gas chromatograph–mass spectrometer (GC–MS). 1-MP was initially oxidized via two different biochemical strategies, including benzene ring and methyl-group attacks. Benzene ring attack was initiated with dioxygenation of the non-methylated aromatic ring via similar degradation pathways of phenanthrene (PHE) by bacteria. For methyl-group attack, mono oxygenase system was involved and more diverse enzymes were needed than that of PHE degradation. This study enhances the understanding of the metabolic pathways of alkylated PAHs and shows the significant potential of Sphingobium sp. MP9-4 for the bioremediation of alkylated PAHs contaminated environments.
Mostrar más [+] Menos [-]Associations between metal exposure and lesion formation in offshore Gulf of Mexico fishes collected after the Deepwater Horizon oil spill Texto completo
2017
Granneman, Jennifer E. | Jones, David L. | Peebles, Ernst B.
The objectives of this study were to: (1) examine patterns of short- and long-term metal exposure within the otoliths of six offshore fish species in varying states of health, as indicated by the presence of external skin lesions, and (2) determine if there was a change in otolith metal concentrations concurrent with the Deepwater Horizon (DWH) oil spill. Otoliths collected from 2011 to 2013 in the Gulf of Mexico (GOM) were analyzed for a suite of trace metals known to be associated with DWH oil. We found that lesioned fish often had elevated levels of otolith 60Ni and 64Zn before, during, and after the DWH oil spill. In addition, metal exposure varied according to species-specific life history patterns. These findings indicate that lesioned individuals were exposed to a persistent source of trace-metals in the GoM prior to the oil spill.
Mostrar más [+] Menos [-]Binary mixture toxicities of triphenyltin with tributyltin or copper to five marine organisms: Implications on environmental risk assessment Texto completo
2017
Yi, Xianliang | Bao, Vivien W.W. | Leung, Kenneth M.Y.
Triphenyltin (TPT) often coexists with tributyltin (TBT) and Cu in coastal waters worldwide. The combined toxic effect of TPT and TBT has always been assumed to be additive without any scientific proof, and the combined effect of Cu and TPT on marine organisms has not been vigorously studied. This study, therefore, investigated the acute toxicity of binary mixture of TPT/Cu and TPT/TBT to five selected marine species including Thalassiosira pseudonana, Skeletonema costatum, Tigriopus japonicus, Brachionus koreanus and Oryzias melastigma. The interaction between TPT and TBT or Cu was modeled antagonistic based on concentration addition (CA) model, while it was synergistic according to response addition (RA) model. Both model well predicted the toxicity of binary mixtures to the five organisms. As for the environmental risk assessment, CA overestimated the toxicity in most cases and thus is a more conservative model than RA model for assessing the toxicity of these chemical mixtures.
Mostrar más [+] Menos [-]Geographic and temporal patterns of variation in total mercury concentrations in blood of harlequin ducks and blue mussels from Alaska Texto completo
2017
Savoy, Lucas | Flint, Paul | Zwiefelhofer, Denny | Brant, Heather | Perkins, Christopher | Taylor, Robert | Lane, Oksana | Hall, Jeff | Evers, David | Schamber, Jason
We compared total mercury (Hg) concentrations in whole blood of harlequin ducks (Histrionicus histrionicus) sampled within and among two geographically distinct locations and across three years in southwest Alaska. Blue mussels were collected to assess correlation between Hg concentrations in locally available forage and birds. Mercury concentrations in harlequin duck blood were significantly higher at Unalaska Island (0.31±0.19 mean±SD, μg/g blood) than Kodiak Island (0.04±0.02 mean±SD, μg/g blood). We found no evidence for annual variation in blood Hg concentration between years at Unalaska Island. However, blood Hg concentration did vary among specific sampling locations (i.e., bays) at Unalaska Island. Findings from this study demonstrate harlequin ducks are exposed to environmental sources of Hg, and whole blood Hg concentrations are associated with their local food source.
Mostrar más [+] Menos [-]Characteristics of mass concentration, chemical composition, source apportionment of PM2.5 and PM10 and health risk assessment in the emerging megacity in China Texto completo
2017
Jiang, Nan | Yin, Shasha | Guo, Yue | Li, Jingyi | Kang, Panru | Zhang, Ruiqin | Tang, Xiaoyan
In this study, 228 daily Particulate matter (PM) filters (57 Quartz and 57 Teflon samples for both PM2.5 and PM10, respectively) were collected from an urban site in Zhengzhou in typical months from 2014 autumn to 2015 summer representing the four seasons. PM concentrations, water-soluble inorganic ions, organic carbon, elemental carbon, and elements were determined, and positive matrix factorization was used for source apportionments. Health risks of toxic elements in PM2.5 and PM10 were also evaluated. The annual mean values of PM2.5 and PM10 were higher than the standards in China, and the highest seasonal concentrations of PM2.5 and PM10 were in winter. Secondary inorganic aerosols (SIAs) were the major component, with the ratio of SIAs/PM highest in summer. The seasonal concentrations of SO42− were high in winter and summer. Crustal elements mainly existed in PM2.5–10; however, elements from anthropogenic sources (i.e., Zn, Pb, Cu, As, Cd, and Mo) were more abundant in fine particles than in the coarse fraction. The main pollution sources were dust, SIAs, coal combustion, vehicle and road dust, and industry, accounting for 10%, 26%, 25%, 20% and 15% in PM2.5 and 32%, 14%, 24%, 18% and 8% in PM10, respectively. Dust source has the highest contribution in PM10; however, SIAs source has the highest content in fine particles. The carcinogenic risks of As to children through the daily intake pathway in PM2.5 and PM10 exceeded the acceptable level. Noncarcinogenic risks of As and Cd in PM2.5 and PM10 to children via the daily intake pathway were significant. Moreover, the sum of noncarcinogenic risks in PM10 via inhalation exposure for local residents and that via dermal absorption for children were significant. The details of the pollution characteristics and the results of source apportionments and health risks assessment of PM2.5 and PM10 in this study can play an important role for the government to formulate reasonable and effective policy to mitigate the atmospheric pollution of PM. To our knowledge, this systematic study is the first to investigate the chemical characterizations, source apportionments, and health effects of PM2.5 and PM10 in Zhengzhou.
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