خيارات البحث
النتائج 1561 - 1570 من 3,991
Temporal and spatial distribution of semicarbazide in western Laizhou Bay
2016
Tian, Xiuhui | Xu, Yingjiang | Song, Xiukai | Gong, Xianghong | Liu, Yihao | Zhou, Quanli | Wang, Zhongquan | Xia, Chuanhai
Semicarbazide (SEM), an industrial raw material and the marker residue of nitrofurazone as a veterinary drug, has become a new type of marine pollutant. A standard method (ultra-performance liquid chromatography–tandem mass spectrometry, UPLC–MS/MS) was used to analyze SEM in seawater, sediment, and shellfish. A series of sections and stations were set up in radical distribution in western Laizhou Bay, with six voyages and 150 monitoring samples. The concentrations of SEM in seawater and shellfish were 10−11 and 10−10kg/L, respectively, and no SEM was detected in the sediment. Distribution characteristics at each state, temporal and spatial trends, multivariate analyses, and the causes were analyzed to assess the pollution level, which aimed to offer a database for drafting the national baseline values of SEM in seawater and sediment in future. The data obtained could be used for integrated watershed management of marine environment and economic activities for constructing a blue economic zone of Shandong Peninsula in China.
اظهر المزيد [+] اقل [-]Radiological maps in beach sands along some coastal regions of Turkey
2016
Kucukomeroglu, B. | Karadeniz, A. | Damla, N. | Yesilkanat, C.M. | Cevik, U.
In the present research, the gamma-emitting radionuclides in beach sands along the coastal regions of the Ordu, Giresun and Trabzon provinces, Turkey have been determined. The natural and anthropogenic radionuclide concentrations of the samples have been measured employing a germanium (HPGe) detector with high resolution and purity. The activity for 238U, 232Th, 40K and 137Cs of the samples were found to vary in the range from below detection limit (BDL) to 65Bq·kg−1, from BDL to 28Bq·kg−1, from 9 to 1936Bq·kg−1 and from BDL to 22Bq·kg−1, respectively. The activity concentrations were compared with those in the literature. The associated radiological hazard indices were estimated, and were compared to the internationally recommended values. The radiological map of beach sand in the surveyed area was imaged. The data presented in the study are crucial since they constitute a baseline for the radiological mapping of the region in the future.
اظهر المزيد [+] اقل [-]Essential requirements for catchment sediments to have ongoing impacts to water clarity in the great barrier reef
2016
Gibbs, Mark T.
Increasing concerns over decreasing water quality and the state of coral reefs and seagrass meadows along the inshore and mid-shelf regions of the Great Barrier Reef has led to a large-scale government catchment sediment and nutrient reduction program. However the mechanistic understanding of how fine sediments washed out of catchments and transported within flood plumes leads to ongoing increases in turbidity at locations far downstream from estuaries long after flood plumes have dissipated is poorly understood. Essential criteria which need to be met in order for catchment-derived sediments to play a major role in nearshore water quality are proposed. Preliminary estimates of these essential criteria suggest that it is dynamically possible for fine sediments washed out of catchments during floods to be preferentially re-mobilised at downstream locations following the dissipation of flood plumes. However the longer-term influence of catchment-derived material on water quality is dependent upon the rate of degradation of floc particles that fall out of flood plumes and the rate of background deposition; neither of which are well quantified.
اظهر المزيد [+] اقل [-]FTIR spectroscopy supported by statistical techniques for the structural characterization of plastic debris in the marine environment: Application to monitoring studies
2016
Mecozzi, Mauro | Pietroletti, Marco | Monakhova, Yulia B.
We inserted 190 FTIR spectra of plastic samples in a digital database and submitted it to Independent Component Analysis (ICA) to extract the “pure” plastic polymers present. These identified plastics were polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), high density polyethylene terephthalate (HDPET), low density polyethylene terephthalate (LDPET), polystyrene (PS), Nylon (NL), polyethylene oxide (OPE), and Teflon (TEF) and they were used to establish the similarity with unknown plastics using the correlation coefficient (r), and the crosscorrelation function (CC). For samples with r<0.8 we determined the Mahalanobis Distance (MD) as additional tool of identification. For instance, for the four plastic fragments found in the Carretta carretta, one plastic sample was assigned to OPE due to its r=0.87; for all the other three plastic samples, due to the r values ranging between 0.83 and0.70, the support of MD suggested LDPET and OPE as co-polymer constituents.
اظهر المزيد [+] اقل [-]Sources and sinks of plastic debris in estuaries: A conceptual model integrating biological, physical and chemical distribution mechanisms
2016
Vermeiren, Peter | Muñoz, Cynthia C. | Ikejima, Kou
Micro- and macroplastic accumulation threatens estuaries worldwide because of the often dense human populations, diverse plastic inputs and high potential for plastic degradation and storage in these ecosystems. Nonetheless, our understanding of plastic sources and sinks remains limited. We designed conceptual models of the local and estuary-wide transport of plastics. We identify processes affecting the position of plastics in the water column; processes related to the mixing of fresh and salt water; and processes resulting from the influences of wind, topography, and organism–plastic interactions. The models identify gaps in the spatial context of plastic–organisms interactions, the chemical behavior of plastics in estuaries, effects of wind on plastic suspension–deposition cycles, and the relative importance of processes affecting the position in the water column. When interpreted in the context of current understanding, sinks with high management potential can be identified. However, source–sink patterns vary among estuary types and with local scale processes.
اظهر المزيد [+] اقل [-]OC/EC from PM10 in the vicinity of Turów lignite open-pit mine (SW Poland): Carbon isotopic approach
2016
Kosztowniak, Elżbieta | Ciężka, Monika | Zwoździak, Anna | Górka, Maciej
Concentrations of PM10 (particulate matter less than 10 μm in diameter) were measured at sampling points located in the vicinity of the Turów open-pit mine, southwest Poland, in April 2008. The samples were analysed by isotope ratio mass spectrometry (IR-MS) to determine the stable carbon isotope compositions of organic carbon (δ13COC) and elemental carbon (δ13CEC). The daily PM10 concentrations ranged from 15 to 99 μg m−3 with an average value of 50 ± 24 μg m−3. The analysed δ13COC values ranged from −25.1 to −19.9‰ with an average value of −23.1 ± 1.9‰, and the values of δ13CEC ranged from −25.6 to −24.1‰ with an average value of −25.0 ± 0.5‰. Additionally, the average δ13CTC value of lignite from the open-pit mine reached −25.8‰, and calculated δ13COC of lignite using an isotopic mass balance (IMB) value reaches −25.7 ± 0.1‰, whereas lignite δ13CEC value reaches −25.9 ± 0.2‰. The calculated major possible sources indicated that organic carbon (OC) in PM10 are represented probably by primary OC originated from the local lignite open-pit mine, whereas elemental carbon (EC) in PM10 are probably derived from local coal/lignite combustion products. If a data base of δ13COC and δ13CEC values from other possible “pure” sources (coal/gasoline/diesel/biomass/etc) is created, it will be possible to calculate individual isotopic mass balances for OC and for EC, which would yield more information than was obtained for total carbon (TC). The method could be a new and very helpful tool for calculating the percentage input of possible sources of OC and EC in atmospheric particles, and it can be applied to data from locations throughout the whole world.
اظهر المزيد [+] اقل [-]Histopathological and apoptotic changes on marine mussels Mytilus galloprovincialis (Lamark, 1819) following exposure to environmental pollutants
2016
Yavaşoğlu, Altuğ | Özkan, Dilara | Güner, Adem | Katalay, Selma | Oltulu, Fatih | Yavaşoğlu, NÜlkü Karabay
Marine bivalve mussels, especially Mytilus species are an earlywarning system used for determining of damage caused by the various aquatic pollutions. In the present study, Mytilus galloprovincialis L. (black mussel) have been utilised as a biomonitoring organism to reveal environmental pollution in the Aliaga, Foca and Urla where located along the Izmir Coast of Turkey. Mussels were collected at these areas and gill and hepatopancreas (digestive gland) tissues were excised. mRNA expressions of initiator (caspase-2 and −8) and executioner (caspase −3/7–1, −3/7–2, −3/7–3 and −3/7–4) caspases of mussels tissues in areas exposed to pollution agent have been observed. TUNEL immunoreactivity in paralel to histopathological changes in both Aliaga and Foca areas were compared with Urla. This study is the first report to reveal the pollution with apoptotic expression on mussels in the coast of Turkey.
اظهر المزيد [+] اقل [-]Role of environmental particulate matters on corrosion of copper
2016
Saha, D. | Pandya, A. | Singh, J.K. | Paswan, S. | Singh, D.D.N.
Effect of environmental particulate materials on kinetics and mechanism of corrosion of industrial grade copper exposed in different parts of India is investigated. It is observed that the level of particulate materials in the atmosphere has more dominant role than the acidic gases on initiation of corrosion, formation of protective patina on the surface of the exposed samples leading to mitigation of corrosion. The identification of corrosion products formed on the surface of exposed samples by Raman spectroscopy provides very vital information to explain the observed corrosion rate of the metal computed in different environments. Electrochemical anodic polarization of the exposed samples supports the mechanism proposed for accelerating and protective effect on corrosion of the metals exposed in different environments.
اظهر المزيد [+] اقل [-]Synoptic weather evolution and climate drivers associated with winter air pollution in New Zealand
2016
Fiddes, S.L. | Pezza, A.B. | Mitchell, T.A. | Kozyniak, K. | Mills, D.
Particulate matter pollution of less than 10 μm in diameter (PM10) is a problem for some regional and urban centres across New Zealand during the winter period when solid fuel (wood and coal) fires are used for home heating. Elevated levels of PM10 concentrations occur during stable atmospheric conditions, when cool air temperatures and low wind speeds allow for a surface inversion to occur and trap PM10. This study examined the relationships between PM10 and local and large-scale synoptic conditions at daily and seasonal scales. Minimum temperature and wind speed were both negatively correlated with PM10 during the winter season, whilst the combination of the two can explain 30–54% of variability in average PM10. Synoptic-scale daily composites of high PM10 days showed the evolution of an anticyclone in the Tasman Sea, with an injection of cool air over New Zealand and persistent south-westerly winds leading to cold and stable conditions on the day of exceedance. Both of these results indicate that there is some potential for predicting days in which atmospheric conditions could favour elevated PM10 concentrations. Furthermore, at the seasonal scale, weaker westerly winds were found to be associated with winters with higher exceedance days, although the relationship is not straightforward. These characteristics can be associated with other, predictable large-scale climate drivers such as the El Niño-Southern Oscillation, and may aid in identifying years in which a higher risk of PM10 pollution events exists.
اظهر المزيد [+] اقل [-]Biases and best approaches for assessing debris ingestion in sea turtles, with a case study in the Mediterranean
2016
Casale, Paolo | Freggi, Daniela | Paduano, Valentina | Oliverio, Marco
In a sample of 567 loggerhead turtles (Caretta caretta) from the central Mediterranean, debris occurrence varied according to methods and turtle source, and was up to 80% in pelagic turtles. Frequencies of plastic types, size and color are also reported. These results and a critical review of 49 studies worldwide indicate that: (i) the detected occurrence of plastic (% turtles) is affected by several factors (e.g., necropsy/feces, ecological zone, type and date of finding, captivity period for feces collection), (ii) mixed dataset and opportunistic approaches provide results which are biased , not comparable, and ultimately of questionable value, (iii) only turtles assumed to have had a normal feeding behaviour at the time of capture or death should be considered, (iv) turtle foraging ecology and possible selectivity may undermine the use of turtles as indicator species for monitoring marine litter, as recently proposed for the Mediterranean.
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