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结果 1781-1790 的 4,302
Are shipwrecks a real hazard for the ecosystem in the Mediterranean Sea?
2017
Renzi, Monia | Romeo, Teresa | Guerranti, Cristiana | Perra, Guido | Canese, Simonepietro | Consoli, Pierpaolo | Focardi, Silvano E. | Berti, Claudio | Sprovieri, Mario | Gherardi, Serena | Salvagio, Daniela | Giaramita, Luigi | Esposito, Valentina | Battaglia, Pietro | Giacobbe, Salvatore | Andaloro, Franco
The aim of the present study was to evaluate the hazard from shipwrecks on communities by a holistic approach taking into account different effects on biological communities. Multibeam and Remotely Operated Vehicles surveys recorded ecological assessment of fish and benthic species on three shipwrecks flooded during the Second World War on Maërl beds habitats in the strait of Sicily. Pollution levels of a wide range of chemicals of ecotoxicological concern were also measured in sediments and in fish species from different trophic levels. Statistical analysis evidenced significant differences among pollutant levels between both sediments and fish collected in shipwreck sites and controls. Concerning fish, significant effects due to the vessel's cargo type and flooding position are recorded. In spite of that, our results underline that shipwrecks are also a hotspots of biodiversity and a habitat for preservation strategies in marine ecosystems that need to be monitored.
显示更多 [+] 显示较少 [-]Trends of BTEX in the central urban area of Iran: A preliminary study of photochemical ozone pollution and health risk assessment
2017
Hajizadeh, Yaghoub | Mokhtari, Mehdi | Faraji, Maryam | Mohammadi, Amir | Nemati, Sepideh | Ghanbari, Reza | Abdolahnejad, Ali | Fard, Reza Fouladi | Nikoonahad, Ali | Jafari, Negar | Miri, Mohammad
The Environmental Protection Agency (USEPA) has identified Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) as hazardous air pollutants. In this study, BTEX sampling was conducted at 20 sites during summer 2015 and winter 2016 in Yazd. Concentrations of BTEX were analyzed using a gas chromatograph with a flame ionization detector (GC-FID). In addition, ozone formation potential (OFP) and the health risks of BTEX were calculated. Spatial mapping was accomplished using the Kriging method. The obtained concentrations of total BTEX ranged from 8 to 560 μg/m3. The highest average individual values belonged to toluene and xylene (38 ± 42 and 41 ± 45 μg/m3, respectively). Seasonal variation showed a downward trend from summer to winter. The peak BTEX emissions occurred in the evenings, due to rush hour traffic and meteorological factors. Spatial analysis showed that the maximum levels of BTEX occurred on high traffic roads or near fuel stations. Significant correlation coefficients between benzene and other BTEX compounds revealed that BTEX were emitted from main sources including gasoline vehicles and stations. The mean ratio of toluene/benzene (T/B) in summer (1.8) was more than winter (1.4). The seasonal changes in T/B ratio possibly were attributed to photochemistry, meteorology, and emission aspects. The OFP values were 720 ± 729 and 375 ± 319 μg/m3 in summer and winter, respectively. OFPs, ranked maximum to minimum, were as follows: xylene > toluene > ethylbenzene > benzene. Although the values of the non-cancer risk of BTEX were under permissible recommended level, a cancer risk still exists because of high values of airborne benzene.
显示更多 [+] 显示较少 [-]Can benthic quality assessment be impaired by uncertain species sensitivities?
2017
Chuševė, Romualda | Daunys, Darius
This study tested robustness of mathematically defined species sensitivity with manipulation of disturbance gradient coverage by datasets on two different pressures and two depth zones of the central Baltic Sea. The results indicate large differences of sensitivity values for the same species when depth range changed. After addition of samples from impacted sites to the control datasets, estimated sensitivity values decreased for half of analysed species. Sensitivity of tolerant species appeared to be highly dependent on the coverage of disturbance gradient by the dataset, while sensitive species were highly robust to this effect. Although pressure type and coverage of disturbance gradient by the dataset was important, sensitivity changes were primarily linked to the altered environmental conditions. It is suggested that sensitivity values based on natural variability of pre-selected communities will better integrate the role of important environmental factors and increase robustness of discrimination between disturbed and undisturbed sites.
显示更多 [+] 显示较少 [-]The effects of sulfur amendments on the geochemistry of sulfur, phosphorus and iron in the mangrove plant (Kandelia obovata (S. L.)) rhizosphere
2017
Li, Jian | Junyi, Yu | Jingchun, Liu | Chongling, Yan | Haoliang, Lu | Spencer, Kate L.
P (phosphorus) and Fe (iron) are limiting elements and S (sulfur) is an important element of the biogeochemical cycle in the mangrove environment. To assess the effects of sulfur on the geochemical cycling of Fe and P at the sediment-plant interface, the speciation distributions of Fe, P and S in sediments were examined. The data showed that higher proportions of amorphous Fe, Fe-bound phosphate, chromium reducible sulfur and elemental sulfur were found in the rhizosphere, while more crystalline Fe, exchangeable phosphate and acid-volatile sulfide were determined in the non-rhizosphere. Sulfate application induced an increase in the Ex-P concentration, high P accumulation and high iron plaque deposition in the roots. In conclusion, sulfate applications had a significant influence on the geochemical cycling of Fe and P in the sediments. It significantly curtailed the Fe and P limit to plant growth and enhanced plant resistance to the rugged surroundings in mangrove.
显示更多 [+] 显示较少 [-]Concentrations of mercury and other trace elements in two offshore skates: sandy ray Leucoraja circularis and shagreen ray L. fullonica
2017
Nicolaus, E.E Manuel | Barry, Jon | Bolam, Thi P.C. | Lorance, Pascal | Marandel, Florianne | McCully Phillips, Sophy R. | Neville, Suzanna | Ellis, Jim
Trace metal concentrations in muscle and liver tissues from two offshore species of skate were examined. Concentrations of mercury in muscle of Leucoraja circularis (n=20; 23–110.5cm total length, 157–490m water depth) and L. fullonica (n=24; 28.5–100cm total length, 130–426m water depth) were 0.02–1.8 and 0.04–0.61mgkg−1, respectively. Concentrations of both As and Hg increased with total length. Only the largest specimen had a concentration of Hg in muscle >1.0mgkg−1. Data were limited for specimens>90cm long, and further studies on contaminants in larger-bodied skates could usefully be undertaken.
显示更多 [+] 显示较少 [-]Freshwater lenses as ecological and population sustenance, case study in the coastal wetland of Samborombón Bay (Argentina)
2017
Tanjal, Carolina | Carol, Eleonora | Richiano, Sebastián | Santucci, Lucia
Freshwater lenses associated to shell ridges and sand sheets exist on the coastal wetland of Samborombón Bay. As they constitute one of the most vulnerable aquifer systems, it is the aim of this study to determine the hydrogeochemical processes that condition the chemical quality of its groundwater and to assess their present and future capability as sustenance of native woods and local villagers. To achieve this, hydrogeomorphological field surveys were made and groundwater samples were taken. Results show that lenses have a mean thickness of 12m and its chemical quality depends on the dissolution of CO2(g) and carbonates, weathering of silicates and ion exchange. Lenses can be affected by long-term climatic variability and mining. The study of morphology and geochemistry of the freshwater lenses bring lights into important information about the management of water resources and conservation of the environment.
显示更多 [+] 显示较少 [-]Detecting long-term temporal trends in sediment-bound metals in the western Adriatic (Mediterranean Sea)
2017
Lopes-Rocha, Marilia | Langone, Leonardo | Miserocchi, Stefano | Giordano, Patrizia | Guerra, Roberta
Major and trace metal concentrations were determined in western Adriatic sediment cores. Based on sediment chronology, the earliest anthropogenic influence appeared as a Zn and Pb increase in the Po River prodelta starting from ~1914. The increasing contamination signal of these trace metals propagated southward as far as 450km with a growing delay, taking ~10years to reach the south Adriatic Sea. Although greater inventories of excess trace metals in the northern sector pointed to the influence of the intense human activities in the Po River drainage basin and Venice lagoon system, we observed a reduction of excess trace metals from mid-1980s, related to the implementation of stricter environmental regulations on chemical wastewaters. In contrast, an increase in trace metal accumulation in surficial sediment from the 2000s in front of the cities of Ancona and Bari suggested a recent local input of trace metals, probably due to harbor activities.
显示更多 [+] 显示较少 [-]Pollutants and biomarker responses in two reef fish species (Haemulon aurolineatum and Ocyurus chrysurus) in the Southern Gulf of Mexico
2017
Gold-Bouchot, Gerardo | Rubio-Piña, J. | Montero-Muñoz, J. | Ramirez-Miss, N. | Echeverría-García, A. | Patiño-Suarez, V. | Puch-Hau, C.A. | Zapata-Pérez, O.
The environmental quality differences between two groups of reefs in the Veracruz Reef System were evaluated. The North group of reefs is very close to Veracruz, an urban and port zone, whereas the South group is more isolated, with minor anthropogenic disturbances. To prove the hypothesis that the North group is more affected by anthropogenic activities, the concentrations of hydrocarbons in liver, metals and metalloids such as Se, As, Ba, Cd, Hg and V in muscle, and PAH metabolites in bile were evaluated, and related to biomarkers (transcript abundance of cytochrome P4501A, Vitellogenin, and Glutathione-S-transferase) in two species of fish: Haemulon aurolineatum and Ocyurus chysurus. H. aurolineatum presents the highest concentrations for many pollutants, but O. chysurus shows the most significant differences in pollutant concentrations and biomarkers between the two reef groups, suggesting that this species could be used as a sentinel in future studies in the Gulf of Mexico.
显示更多 [+] 显示较少 [-]On-field and laboratory measurement of nanoparticle emission in the wake of gasoline vehicle
2017
Banerjee, Tandra | Christian, R.A.
Nanoparticle emission from gasoline driven vehicles is reported to be significantly lower compared to diesel vehicles. Accordingly, there is no threshold limit implemented by the regulatory authorities in India for gasoline driven vehicles. Recent studies however indicate that this is true as far as the mass concentration of the nanoparticles is concerned. The number concentration of nanoparticles particularly of smaller dimensions is reported to be significantly higher for gasoline driven vehicles under certain operating range of speed and load. Smaller the dimension of the particles more are their residence time in environment and more susceptible are these particles to be inhaled by human respiratory and cardiovascular system. Thus an estimate of the size distribution of nano-sized particulate matter emission from gasoline driven vehicle is of immense importance in context to Indian urban population. In this direction, laboratory measurements are reported for the nanoparticle size distribution emitted from a gasoline engine under different loading conditions. On-field measurements are carried out in the wake of a stationary vehicle under idling and throttling condition. Simultaneous measurement of vehicular acceleration and deceleration is also reported along with nanoparticle distribution in the wake of a moving vehicle. The measurements reported in this paper reveal the need for deciding threshold value of number concentration to be implemented for gasoline vehicles by the Indian regulatory authorities.
显示更多 [+] 显示较少 [-]Otolith microchemistry: Insights into bioavailable pollutants in a man-made, urban inlet
2017
Andronis, Christina | Evans, Noreen J. | McDonald, Bradley J. | Nice, Helen E. | Gagnon, Marthe Monique
Black bream (Acanthopagrus butcheri) were collected from an artificial inlet, Claisebrook Cove, Western Australia. Claisebrook Cove is adjacent to an historic contaminated site that was remediated during the 1990s. It was later identified as a priority area due to elevated levels of sediment contaminants including Zn, Cu, and Pb. Black bream were collected from this cove in 2005 and 2012 and their otoliths were analysed by laser ablation inductively coupled plasma mass spectrometry of the most recent growth zone. Levels of Zn and Mn, which are metabolically regulated, did not correlate with sediment contamination. However, reduction in sediment Cu levels over time coincided with reduced Cu otolith levels from 2005 to 2012. Results indicate that the elemental composition of the marginal edge of Black bream otoliths can identify bioavailable contaminants in an urban estuary and, with monitoring, can be utilized to establish long-term trends.
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