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Volatile organic compound levels at one site in Rome urban air Texto completo
2014
Fanizza, Carla | Incoronato, Federica | Baiguera, Silvia | Schiro, Roberto | Brocco, Domenico
Volatile organic compound (VOC), nitrogen dioxide (NO2) and ozone (O3) concentrations were measured at one site in Rome urban air during 2011. The seasonal mean concentrations of VOCs varied from 78μg m−3 in winter to 37μg m−3 in summer. Total aromatic concentration was reduced by 59% during summertime, alkanes of 39% and alkenes of 71%. VOC diurnal pattern exhibited a primary peak during the morning and a secondary peak in the evening hours coinciding with rush–hour traffic. The high correlation between benzene and toluene evidenced their common origin probably due to vehicular traffic. In summer isoprene diurnal profile showed both biogenic and anthropogenic origin. NO2 and O3 daily trends during summertime evidenced both photostationary state typical conditions and photochemical smog episodes. VOC and O3 trends also evidenced a reduction in VOC levels during O3 formation. Based on the Maximum Incremental Reactivity scale, the highest contributors to ozone production in Rome were propene, ethene and toluene. Comparing data found in Rome at the same site in 1992, 2007 and 2011, a decreasing trend in VOC levels was observed, suggesting the effectiveness of European Directives on air quality. In addition, our results were confirmed by similar data found in other urban areas around the world.
Mostrar más [+] Menos [-]Ambient particulate pollution during Chinese Spring Festival in urban Lanzhou, Northwestern China Texto completo
2014
Zhao, Suping | Yu, Ye | Yin, Daiying | Liu, Na | He, Jianjun
The effect of firework displays on ambient particulate pollution in a typical valley city in Northwestern China was evaluated based on high temporal resolution atmospheric particle size distribution (10–10 000nm) data and particle mass concentrations in different sizes obtained during 25th January – 24th February, 2013. Firework displays have significant impact on particle number concentrations in accumulation mode (100–1 000nm), especially in 200–500nm, as well as PM1 mass concentrations. The hourly mean number concentration in 200–500 nm and PM1 mass concentration during the peak hour of firework displays were 11 800.2±2 548.0cm–3 and 214.1±31.2μg m−3, which are approximately 6 times and 2 times of that before the festival, respectively, with a maximum10–min mean number concentration in size range 100–1 000 nm reaching 3.8×104cm−3 on the New Year's Eve (00:10 BT 10th February, 2013). It was estimated that local emissions and firework displays contributed 74.6% and 37.0%, respectively, to the number concentration of particles less than 1 000nm. On short–time scale, the contribution of firework displays on local particulate pollution is obvious and should not be ignored, especially on fine particulate pollution.
Mostrar más [+] Menos [-]High-levels of microplastic pollution in a large, remote, mountain lake Texto completo
2014
Free, Christopher M. | Jensen, Olaf P. | Mason, Sherri A. | Eriksen, Marcus | Williamson, Nicholas J. | Boldgiv, Bazartseren
Despite the large and growing literature on microplastics in the ocean, little information exists on microplastics in freshwater systems. This study is the first to evaluate the abundance, distribution, and composition of pelagic microplastic pollution in a large, remote, mountain lake. We quantified pelagic microplastics and shoreline anthropogenic debris in Lake Hovsgol, Mongolia. With an average microplastic density of 20,264 particles km−2, Lake Hovsgol is more heavily polluted with microplastics than the more developed Lakes Huron and Superior in the Laurentian Great Lakes. Fragments and films were the most abundant microplastic types; no plastic microbeads and few pellets were observed. Household plastics dominated the shoreline debris and were comprised largely of plastic bottles, fishing gear, and bags. Microplastic density decreased with distance from the southwestern shore, the most populated and accessible section of the park, and was distributed by the prevailing winds. These results demonstrate that without proper waste management, low-density populations can heavily pollute freshwater systems with consumer plastics.
Mostrar más [+] Menos [-]Detection of multiple potentially pathogenic bacteria in Matang mangrove estuaries, Malaysia Texto completo
2014
Ghaderpour, Aziz | Mohd Nasori, Khairul Nazrin | Chew, Li Lee | Chong, V. C. (Ving Ching) | Thong, Kwai Lin | Chai, Lay Ching
The deltaic estuarine system of the Matang Mangrove Forest Reserve of Malaysia is a site where several human settlements and brackish water aquaculture have been established. Here, we evaluated the level of fecal indicator bacteria (FIB) and the presence of potentially pathogenic bacteria in the surface water and sediments. Higher levels of FIB were detected at downstream sampling sites from the fishing village, indicating it as a possible source of anthropogenic pollution to the estuary. Enterococci levels in the estuarine sediments were higher than in the surface water, while total coliforms and E. coli in the estuarine sediments were not detected in all samples. Also, various types of potentially pathogenic bacteria, including Klebsiella pneumoniae, Serratia marcescens and Enterobacter cloacae were isolated. The results indicate that the Matang estuarine system is contaminated with various types of potential human bacterial pathogens which might pose a health risk to the public.
Mostrar más [+] Menos [-]Interactive effects of hypoxia and PBDE on larval settlement of a marine benthic polychaete Texto completo
2014
Shin, Paul K.S. | Gopalakrishnan, Singaram | Chan, Alice K.Y. | Qian, P.Y. | Wu, Rudolf S.S.
Marine benthic polychaete Capitella sp. I is widely known to adapt to polluted habitats; however, its response to xenobiotics under hypoxic conditions has been rarely studied. This research aimed to test the hypothesis that interactive effects of hypoxia and congener BDE-47 of polybrominated diphenyl ethers (PBDE), which is ubiquitous in marine sediments, may alter the settlement of Capitella sp. I. Our results revealed that under hypoxic condition, settlement success and growth in body length of Capitella larvae were significantly reduced compared to those under normoxia of similar BDE-47 concentration. While no significant changes in morphology of settled larvae were noted in both exposure conditions, the presence of BDE-47 could enhance polychaete growth. The present findings demonstrated that the interactive effects of hypoxia and environmentally realistic concentrations of BDE-47 in sediments could affect polychaete settlement, which, in turn, reduce its recruitment and subsequent population size in the marine benthic ecosystem.
Mostrar más [+] Menos [-]Essential, trace and toxic element concentrations in the liver of the world’s largest bony fish, the ocean sunfish (Mola mola) Texto completo
2014
Perrault, Justin R. | Buchweitz, John P. | Lehner, Andreas F.
No studies document essential (calcium, magnesium, phosphorus, potassium, sodium), trace (barium, boron, chromium, cobalt, copper, iron, manganese, molybdenum, selenium, zinc) or toxic element (antimony, arsenic, cadmium, lead, mercury, thallium) concentrations in any members of the family Molidae, including the world’s largest bony fish, the ocean sunfish (Mola mola). Here, we analyzed 21 elements in the liver of one M. mola. These values were compared to liver concentrations in multiple species with spatial and dietary overlap. Concentrations of calcium (3339ppm wet weight) and iron (2311ppm wet weight) were extremely elevated in comparison to a number of other fish species, indicating that calcium and/or iron toxicity may have occurred in this animal. Concentrations of toxic elements were generally low, with the exception of cadmium (3.5ppm). This study represents the first report of essential, trace and toxic elements in this species.
Mostrar más [+] Menos [-]Offshore platforms: Comparison of five benthic indicators for assessing the macrozoobenthic stress levels Texto completo
2014
Spagnolo, A. | Punzo, E. | Santelli, A. | Scarcella, G. | Strafella, P. | Grati, F. | Fabi, G.
Within the European Water Framework Directive, many studies have been conducted to evaluate the sensitivity/robustness of a variety of indices in relation to natural or anthropogenic disturbance events. However, these indices have rarely been applied to verify the impacts of disturbances in offshore environments, though the Marine Strategy Framework Directive recommends their use for assessing benthic community conditions and functionality. The aim of this paper was to determine which biotic indicator performed the best for detecting the impacts of offshore structures on benthic populations in the Adriatic Sea. The impacts of four rigs were investigated six months after their installation, and the H′, AMBI, m-AMBI, BENTIX, and BOPA indices were assessed. Although these five indices delivered some contradictory results because of the differences in their structure and discrepancies in their assignment of species sensitivity, the BENTIX, H′ and BOPA indices appear to evaluate stress levels better than the AMBI and m-AMBI indices, which tend to provide results that are slightly overly optimistic.
Mostrar más [+] Menos [-]Occurrence of Enterococcus species with virulence markers in an urban flow-influenced tropical recreational beach Texto completo
2014
Ahmad, Asmat | Dada, Ayokunle Christopher | Usup, Gires | Lee Yook Heng,
Median enterococci counts of beach water samples gradually increased at statistically significant levels (χ2: 26.53, df: 4; p<0.0001) with increasing proximity to river influx. The difference in proportion of antibiotic resistant enterococci in beach water and river water samples was statistically significant (p<0.05) for the tested antibiotics with river isolates generally presenting higher resistance frequencies. Virulence genes cyl, esp, gelE and asa were detected at varying frequencies (7.32%, 21.95%, 100% and 63.41% respectively) among river isolates. On the other hand, the prevalence of these genes was lower (0%, 20%, 67.27% and 41.82% respectively) among beach water isolates. Multi-Locus-Sequence-Typing analysis of Enterococcusfaecalis presented four sequence types (ST) one of which shared six out of seven tested loci with ST6, a member of the clonal complex of multi-drug resistant strains associated with hospital outbreaks.
Mostrar más [+] Menos [-]The usefulness of transplantation studies in monitoring of metals in the marine environment: South African experience Texto completo
2014
Greenfield, R. | Brink, K. | Degger, N. | Wepener, V.
Due to their close proximity to the point sources of pollution, estuaries and harbours are exposed to metals. Mussels are used worldwide to monitor marine pollution due to their ability to take up contaminants and the ease of transplantation. Mussels were collected from two reference sites and transplanted in Richards Bay Harbour (2006 and 2010) and in three harbours. Transplanted and resident mussels were removed after 6weeks exposure and metal concentrations were analysed using ICP-MS techniques. Transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to regulation of metals by the resident mussels. Metal regulation was greater in mussels that are continuously submerged as opposed to those that undergo tidal influences. For monitoring it is essential that the reference population for transplantation is considered carefully as upwelling events in the pristine reference location results in significant increases in metal bioaccumulation.
Mostrar más [+] Menos [-]Diving associated coral breakage in Hong Kong: Differential susceptibility to damage Texto completo
2014
We conducted the first quantitative assessment of coral breakage along a gradient of diving activities in Hong Kong, the most densely populated city in southern China. A survey of six 1×25m transects at seven sites revealed a total of 81 broken corals, among which 44% were branching, 44% plate-like and 12% massive. There were 3–19 broken colonies per site. At most study sites, the percentage of broken corals exceeded the recommended no-action threshold of 4%, suggesting that management intervention is justified. There was a significant positive correlation between the number of broken coral colonies and the number of divers visiting the site. The branching Acropora and the plate-like Montipora suffered from much higher frequency of damage than their relative abundance, raising the concern that the cumulative impact of such differential susceptibility to breakage may affect coral community composition.
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