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Chemical characterization of roadside PM2.5 and black carbon in Macao during a summer campaign
2014
Song, Shaojie | Wu, Ye | Zheng, Xuan | Wang, Zhishi | Yang, Liu | Li, Jiaqi | Hao, Jiming
Air pollution is the leading environmental concern in Macao. The temporal variations of particulate matter (PM) and black carbon (BC) mass concentrations and the size–resolved PM2.5 chemical compositions, including trace elements and carbonaceous species, were measured in Macao during a near–road summer campaign. The average concentrations for PM10, PM2.5 and BC at a roadside measurement site were 37.8μg m−3, 31.4μg m−3 and 5.6μg m−3, respectively. Results showed that local emissions contributed at least 35% to PM2.5 mass in Macao. Higher BC concentrations were observed in the daytime than at night, consistent with the diurnal variations of traffic flow. Factor analysis classified trace elements into three categories, representing crustal sources (Mg, Si, Al, Na, Fe, Ca and K), road traffic sources (Cu and Co) and secondary inorganic particle formation (S). Crustal elements and road traffic elements were enriched in the size ranges of >1.0μm and <0.2μm, respectively. The unimodal distribution pattern with a peak at <0.2μm for organic carbon (OC) was probably due to secondary organic aerosol formation, whereas about 70% of elemental carbon (EC) was in the size range of 0.2–1.0μm. Secondary organic aerosols were found to be a strong contributor to PM in the size ranges of <0.2μm and 1.0–2.5μm.
Показать больше [+] Меньше [-]Workplace personal exposure to respirable PM fraction: a study in sixteen indoor environments
2014
Saraga, Dikaia E. | Volanis, Lefteris | Maggos, Thomas | Vasilakos, Christos | Bairachtari, Kyriaki | Helmis, Costas G.
The present paper focuses on respirable particulate matter (RPM) measurements conducted at the breathing zone of adult volunteers in sixteen different working environments: two offices, a house, a chemical laboratory, a non–smoking shop, a pharmacy store, a car garage, a hairdresser's store, a photocopy store, a taxi, a gym, a mall, a restaurant, a bar, a kiosk and a school. The sixteen different cases were categorized according to the location, the type of the activities taking place indoors, the number of occupants, the proximity to heavy traffic roads, the ventilation pattern etc. According to the results, the maximum particle concentration (in average 285μg m−3) was recorded at the hairdresser store while the minimum concentration was measured in the cases of the housewife and the employee in the non–smoking shop (in average 30μg m−3). The results indicated smoking as a factor which strongly influences the exposure levels of both smokers and passive smokers. Furthermore, it was found that the building ventilation pattern comprises an important factor influencing the exposure levels especially in cases of buildings with great number of visitors (resuspension) and smoking.
Показать больше [+] Меньше [-]A year-long comparison of particle formation events at paired urban and rural locations
2014
Jun, Yun-Seok | Jeong, Cheol-Heon | Sabaliauskas, Kelly | Richard Leaitch, W. | Evans, Greg J.
Ultrafine particle size distribution data were collected in downtown Toronto and rural Egbert from May 2007 to May 2008. Particle formation events were observed in both locations and contributed to increased concentrations of particles less than 25nm in diameter. These events were more frequent in spring and fall and rarely occurred in winter. Stronger solar radiation and drier air were correlated with the occurrence of formation events at both locations. Nucleation events occurred simultaneously at both sites on 10% of the days, and these events involved a shared air mass. Half of these simultaneous events were associated with northern air masses and only a quarter with southerly air masses. The higher loading of aged particles in southerly air masses transported from upwind industrial sectors appeared to limit the occurrence of nucleation events. Formation events occurred less frequently in downtown Toronto than at the rural site, and the frequency was lower on weekdays. It is hypothesized that vehicular emissions were responsible for the suppression of nucleation events in downtown Toronto.
Показать больше [+] Меньше [-]Seasonal variations of epipelic algal community in relation to environmental factors in the Istanbul Strait (the Bosphorus), Turkey
2014
Aktan, Y. | Balkıs, N. | Balkıs, N.
This study was implemented to investigate the species composition, abundance, seasonal variations and diversity of epipelic algae, to determine environmental variables affecting them and to reveal the accumulation of total organic carbon in the sediment in the coastal zone of the Istanbul Strait, Turkey. Epipelic algal community consisted of 44 taxa with a low diversity. The sediment structure which is highly unstable due to the high hydrodynamism of the zone played a dominant role as the main factor in the epipelic algal flora along the coasts of Istanbul Strait. Low TOC and high carbonate values also support this result. The dominance of cyanobacteria in some periods and, as a result of this, the record of the lowest diversity index values indicated the effect of nutrient enrichment and the risk of coastal eutrophication. High dominance of cyanobacteria may also be explicated by climate changes considering its effect in the other areas.
Показать больше [+] Меньше [-]Mandating responsible flagging practices as a strategy for reducing the risk of coastal oil spills
2014
Miller, Dana D. | Hotte, Ngaio | Sumaila, U Rashid
As human civilization is becoming more aware of the negative impact our actions can inflict upon the natural world, the intensification of fossil fuel extraction and industrial development is being met with increasing opposition. In Western Canada, proposals that would increase the volume of petroleum transported by pipelines and by tankers through the coastal waters of British Columbia have engaged the province in debate. To ease public concern on the risk of a coastal oil spill, there are additional commitments that involved parties could make. There is evidence to show that the practice of registering vessels under foreign flags of states that have exhibited failure in compliance with international obligations is more common amongst petroleum tankers that have been involved in large-scale oil spills. To prove that they are committed to reducing the risk of oil spills, businesses need to stop registering their vessels under flags of foreign, non-compliant states.
Показать больше [+] Меньше [-]Analysis of nodal point pollution, variability, and sustainability in mesohaline tidal creeks
2014
Muller, Andrew | Müller, Diana
Mesohaline tidal creeks are critical since they may lie at the crossroads of aquatic habitat and urban/sub-urban pressures. The emphasis of this study was to determine the water quality stressor variations within and between tidal creeks and determine whether they serve as nodes of pollutants into the sub-estuary. Measurements of water quality stressors were conducted over a six-year period. The study revealed that characterizing the variability of individual tidal creeks is critical to understanding the process and impacts of stressors in sub-estuarine environments and that the tidal creeks are actually nodal points of sediment and nutrient pollution. This results in hypoxia being controlled within tidal creeks rather than being imported from the parent estuary. The calculated metrics were then used to create a Sustainability Characterization Map. Methods incorporated in this study would be of value to restoration managers, and in the decision-making process of urban and suburban watershed planners.
Показать больше [+] Меньше [-]Occurrence of persistent organic pollutants in marine fish from the Natuna Island, South China Sea
2014
Hao, Qing | Sun, Yu-Xin | Xu, Xiang-Rong | Yao, Zi-Wei | Wang, You-Shao | Zhang, Zai-Wang | Luo, Xiao-Jun | Mai, Bi-Xian
Five marine fish species were collected from the Natuna Island, South China Sea to investigate the occurrence of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs). Concentrations of PBDEs, PCBs, and DDTs in marine fish ranged from 2.85 to 7.82, 14.3 to 48.1, and 7.99 to 40.3ng/g lipid weight, respectively. Higher concentrations of PBDEs, PCBs, and DDTs were observed in Snakefish (Trachinocephalus myops), which might be attributed to their different feeding and living habits. PCBs were the predominant POPs in all marine fish, followed by DDTs and PBDEs. BDE 47 and PCB 153 were the predominant congener of PBDEs and PCBs, respectively. Compositional distribution of DDTs indicated the possible presence of fresh input sources around the Natuna Island. The ratios of o,p′-DDT/p,p′-DDT being less than 1 in fish samples suggested that DDT contributions from dicofol seemed considerably low. New input sources of DDT in South China Sea are worth further research.
Показать больше [+] Меньше [-]Regulation of CYP11B1 and CYP11B2 steroidogenic genes by hypoxia-inducible miR-10b in H295R cells
2014
Nusrin, Suraia | Tong, Steve K.H. | Chaturvedi, G. | Wu, Rudolf S.S. | Giesy, John P. | Kong, Richard Y.C.
Although numerous studies have shown that hypoxia affects cortisol and aldosterone production in vivo, the underlying molecular mechanisms regulating the steroidogenic genes of these steroid hormones are still poorly known. MicroRNAs are post-transcriptional regulators that control diverse biological processes and this study describes the identification and validation of the hypoxia-inducible microRNA, miR-10b, as a negative regulator of the CYP11B1 and CYP11B2 steroidogenic genes in H295R human adrenocortical cells. Using the human TaqMan Low Density miRNA Arrays, we determined the miRNA expression patterns in H295R cells under normoxic and hypoxic conditions, and in cells overexpressing the human HIF-1α. Computer analysis using three in silico algorithms predicted that the hypoxia-inducible miR-10b molecule targets CYP11B1 and CYP11B2 mRNAs. Gene transfection studies of luciferase constructs containing the 3′-untranslated region of CYP11B1 or CYP11B2, combined with miRNA overexpression and knockdown experiments provide compelling evidence that CYP11B1 and CYP11B2 mRNAs are likely targets of miR-10b.
Показать больше [+] Меньше [-]Levels of Cd, Cu, Pb and V in marine sediments in the vicinity of the Single Buoy Moorings (SBM3) at Mina Al Fahal in the Sultanate of Oman
2014
Al-Husaini, Issa | Abdul-Wahab, Sabah | Ahamad, Rahmalan | Chan, Keziah
Recently in the Sultanate of Oman, there has been a rapid surge of coastal developments. These developments cause metal contamination, which may affect the habitats and communities at and near the coastal region. As a result, a study was conducted to assess the level of metal contamination and its impact on the marine sediments in the vicinity of the Single Buoy Moorings 3 (SBM3) at Mina Al Fahal in the Sultanate of Oman. Marine subtidal sediment samples were collected from six different stations of the SBM3 for the period ranging from June 2009 to April 2010. These samples were then analyzed for their level and distribution of the heavy metals of cadmium (Cd), copper (Cu), lead (Pb) and vanadium (V). Overall, low concentrations of all four heavy metals were measured from the marine sediments, indicating that the marine at SBM3 is of good quality.
Показать больше [+] Меньше [-]Congener-specific distribution and bioaccumulation of short-chain chlorinated paraffins in sediments and bivalves of the Bohai Sea, China
2014
Ma, Xindong | Chen, Chen | Zhang, Haijun | Gao, Yuan | Wang, Zhen | Yao, Ziwei | Chen, Jiping | Chen, Jingwen
Short-chain chlorinated paraffins (SCCPs) are a new type of persistent organic pollutants that are of great environmental concern because of their wide distribution. In this study, surface sediments and bivalve samples were collected from the coastal area of the Bohai Sea in China. Total SCCP (ΣSCCP) concentrations in surface sediments and bivalves ranged from 97.4ngg−1 dry weight (dw) to 1756.7ngg−1 dw and 476.4–3269.5ngg−1 dw, respectively. C10-CPs and C11-CPs were the predominant homologue groups in all sediments and bivalves. Specific congener composition analysis and correspondence analysis indicated that the local SCCP source mainly came from CP-42 and CP-52 products, and riverine input had an important function. The biota–sediment accumulation factors of ΣSCCPs for bivalves ranged from 1.08 to 1.61, and a significant correlation indicated that the SCCP congener with higher chlorination degree was more likely to be accumulated in bivalves.
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