خيارات البحث
النتائج 581 - 590 من 2,512
Multivariate statistical approach to identify significant sources influencing the physico-chemical variables in Aerial Bay, North Andaman, India النص الكامل
2014
Jha, Dilip Kumar | Vinithkumar, N.V. | Sahu, Biraja Kumar | Das, Apurba Kumar | Dheenan, P.S. | Venkateshwaran, P. | Begum, Mehmuna | Ganesh, T. | Prashanthi Devi, M. | Kirubagaran, R.
Aerial Bay is one of the harbor towns of Andaman and Nicobar Islands, the union territory of India. Nevertheless, it is least studied marine environment, particularly for physico-chemical assessment. Therefore, to evaluate the annual spatiotemporal variations of physico-chemical parameters, seawater samples collected from 20 sampling stations covering three seasons were analyzed. Multivariate statistics is applied to the investigated data in an attempt to understand the causes of variation in physico-chemical parameters. Cluster analysis distinguished mangrove and open sea stations from other areas by considering distinctive physico-chemical characteristics. Factor analysis revealed 79.5% of total variance in physico-chemical parameters. Strong loading included transparency, TSS, DO, BOD, salinity, nitrate, nitrite, inorganic phosphate, total phosphorus and silicate. In addition, box-whisker plots and Geographical Information System based land use data further facilitated and supported multivariate results.
اظهر المزيد [+] اقل [-]Analysis of total column ozone in Peninsular Malaysia retrieved from SCIAMACHY النص الكامل
2014
Tan, Kok Chooi | Lim, Hwee San | Mat Jafri, Mohd Zubir
Due to lack of observational studies on greenhouse gases in Malaysia, most studies in this field were carried out based on ground station data. These studies did not utilize satellite data from the equatorial area. Satellite remote sensing is one of the most effective approaches for greenhouse gas distribution monitoring on a global scale. As such, satellite remote sensing exhibits a very high spatial and temporal resolution. Variations of ozone concentrations in Peninsular Malaysia were observed and investigated by means of data retrieved from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). The aim of this study was to determine the monthly and seasonal ozone concentrations in Peninsular Malaysia from January 2003 to December 2009. We utilized total column ozone at level 2 of the WFMD version 1.0. A spatial resolution value of 1°×1.25° was used. Analysis indicated that the five selected sites exhibited strong seasonal atmospheric ozone concentration variations. These variations resulted from the significant differences between the northeast monsoon (NEM) and the southwest monsoon (SWM). As the NEM prevails, cold air breaks out from Siberia and spreads to the equatorial region in the form of northeasterly cold surge winds. These winds manifest in low–level anticyclones over Southeast Asia. Inversely, the air masses from the southwest contribute to long–range air pollution. During SWM, the transport of atmospheric ozone by wind is associated with biomass burning in Sumatra, Indonesia. HYSPLIT was also utilized to identify the air pollutant transport between NEM and SWM toward Peninsular Malaysia. Comparisons were made between the ozone data from five sites in 2009. Data were retrieved from SCIAMACHY and the Atmospheric Infrared Sounder (AIRS). The relative difference average of the ozone data measured by SCIAMACHY and AIRS was approximately 6%.
اظهر المزيد [+] اقل [-]Observations of air quality on the outskirts of an urban agglomeration during the implementation of pollution reduction measures النص الكامل
2014
Sun, Yang | Zhang, Junke | Pan, Yuepeng | Wang, Yuesi | Liao, Tingting | Song, Tao
Based on observations at Heshan, a boundary area in the city agglomeration of the Pearl River Delta region in China, atmospheric pollutants such as PM2.5, O3, CO, SO2, NOZ, NO2 and NO were monitored between the 12th and 29th November, 2010. Meteorological parameters, including temperature, humidity, dew point, air pressure, ultraviolet light, wind direction, and wind speed were also measured. By combining the meteorological parameters with the atmospheric pollutant data, we performed Positive Matrix Factorization (PMF) and ozone production efficiency (OPE) analysis to objectively understand the interrelations among the pollutants, as well as between the pollutants and the meteorological factors. During the observation period, there were various meteorological changes such as rainfall, cold air transit, and sunshine that created conditions for the formation or dispersal of pollutants. The study period coincided with the 16th Asian Games, during which time the government adopted strict measures to reduce the discharge of pollutants around the Pearl River Delta area. However, we still observed serious pollution of PM2.5 and O3, of which the highest value of PM2.5 was 210 μg m−3 and the highest value of O3 reached 117 ppb. At the same time, the high concentrations of CO, NO, NO2, NOZ, and SO2 could not be cleared away with rainfall in such a short period of time. On the basis of PMF analysis, we found that three factors influence the air quality of this region: local biomass burning, secondary pollutants of regional transport, and high industrial pollutant emissions. According to OPE analysis, the O3 pollution was mostly found to be VOC–sensitive but occasionally NOX–sensitive for OPE values greater than 10.
اظهر المزيد [+] اقل [-]Contamination and spatial distribution of heavy metals in topsoil surrounding a mega cement factory النص الكامل
2014
Ogunkunle, Clement Oluseye | Fatoba, Paul Ojo
This study assessed the level of contamination of the topsoil by Pb, Cu, Cr, Cd and Zn and the spatial distribution of these heavy metals around a cement factory. Thirty–eight composite soil samples were collected around the cement factory and subjected to nitric–perchloric acid digestion. Total metal contents of the soil were determined by flame atomic absorption spectrophotometry (FAAS) and the data generated were analyzed statistically. Spatial mapping of the distribution of heavy metals was done through the use of Inverse Distance Weighted technique (IDW) of ArcGIS 10. The results showed that the contamination domain of Cd was in the extreme domain while Pb and Cu levels in the soil were in the severe and moderate contamination domains. Zn and Cr posed no potential environmental hazard because of their low level in the soil. The spatial mapping of the heavy metals indicated Pb and Cu enrichment of the soil not only to come from cement production activities but also from vehicular activities while Cd enrichment of the soil was mainly from the cement production. Mapping of Zn and Cr distribution showed that their enrichments in the soil were from cement production activities. From these findings, it is highly recommended that environmental auditing of the cement production line be carried out to reduce the release of pollutants. It is also important that remediation activities be carried out on the soil to reduce the levels of Cd, Pb and Cu to avert potential ecological disasters.
اظهر المزيد [+] اقل [-]Australia’s pesticide environmental risk assessment failure: The case of diuron and sugarcane النص الكامل
2014
Holmes, Glen
In November 2012, the Australian Pesticide and Veterinary Medicines Authority (APVMA) concluded a 12year review of the PSII herbicide diuron. One of the primary concerns raised during the review was the potential impact on aquatic ecosystems, particularly in the catchments draining to the Great Barrier Reef. The environmental risk assessment process used by the APVMA utilised a runoff risk model developed and validated under European farming conditions. However, the farming conditions in the sugarcane regions of the Great Barrier Reef catchments have environmental parameters beyond the currently validated bounds of the model. The use of the model to assess environmental risk in these regions is therefore highly inappropriate, demonstrating the pitfalls of a one size fits all approach.
اظهر المزيد [+] اقل [-]The effect of ocean acidification on carbon storage and sequestration in seagrass beds; a global and UK context النص الكامل
2014
Garrard, Samantha L. | Beaumont, Nicola J.
Ocean acidification will have many negative consequences for marine organisms and ecosystems, leading to a decline in many ecosystem services provided by the marine environment. This study reviews the effect of ocean acidification (OA) on seagrasses, assessing how this may affect their capacity to sequester carbon in the future and providing an economic valuation of these changes. If ocean acidification leads to a significant increase in above- and below-ground biomass, the capacity of seagrass to sequester carbon will be significantly increased. The associated value of this increase in sequestration capacity is approximately £500 and 600 billion globally between 2010 and 2100. A proportionally similar increase in carbon sequestration value was found for the UK. This study highlights one of the few positive stories for ocean acidification and underlines that sustainable management of seagrasses is critical to avoid their continued degradation and loss of carbon sequestration capacity.
اظهر المزيد [+] اقل [-]Organotin contamination in seafood and its implication for human health risk in Hong Kong النص الكامل
2014
Ho, Kevin K.Y. | Leung, Kenneth M.Y.
Organotins (OTs) have caused widespread adverse effects on marine organisms, while they can also induce health problems to humans via consumption of contaminated seafood. This study aimed to quantify the tissue concentrations of OTs in 11 seafood species in Hong Kong, and assess the human health risk for consuming these species. The tongue sole Paraplagusia blochii had the highest concentration of total OTs. Triphenyltin (TPT) accounted for 56–97% of total OTs. The highest hazard quotient (HQ) for TPT was 1.41 in P. blochii, while the HQs for butyltins were much less than 1. The results indicated that it is likely to have certain health risks for consuming P. blochii due to its high TPT contamination. Therefore, TPT should be a priority pollutant of concern. Appropriate management actions should be taken to control its use and release in the region in order to safeguard the marine ecosystem and human health.
اظهر المزيد [+] اقل [-]Evaluation of phytotoxicity of seaport sediments aged artificially by rotary leaching in the framework of a quarry deposit scenario النص الكامل
2014
Bedell, J.-P. | Ferro, Y. | Bazin, C. | Perrodin, Y.
In the framework of an ecological risk assessment of seaport sediments for terrestrial ecosystems when deposited in quarries, we simulated the “ageing” of sediments exposed to rain. This experiment highlighted an inflection point at the solid/liquid ratio 1/25, after which the extraction of pollutants increases moderately. The raw sediments studied inhibited the germination of Lolium perenne and Armeria maritima (a halophytic species) seeds. Furthermore, they affected the early development of L.perenne. The same sediments, leached at a ratio of 1/25, presented a reduction of acute (germination) and chronic (growth) phytotoxicity. The bioconcentration factors of the metals studied decreased with the leached sediment, except for Cu which was still clearly identified in root parts. Thus rotary leaching tests and phytotoxicity bioassays can be used to provide an initial assessment of the ability of plants, particularly halophytes, to colonize deposits of dredged seaport sediments.
اظهر المزيد [+] اقل [-]GC–ITMS analysis of PAH contamination levels in the marine sea urchin Paracentrotus lividus in Sardinia النص الكامل
2014
Angioni, Alberto | Cau, Alessandro | Secci, Marco | Addis, Piero
This paper describes the results of a two-year monitoring study examining the pollution of the sea urchin Paracentrotus lividus by polycyclic aromatic hydrocarbons (PAHs) in Sardinia. GC–ITMS analysis of sea urchin gonads showed the presence of 11 and 12 PAHs in the samples of Capo Pecora, and Capitana, respectively. Fluorene, naphthalene and its two degradation products, 1-methyl-naphthalene, and 2-methyl-naphthalene, were detected in all samples analyzed. The ΣPAH residues showed a similar trend over the two-year sampling period. Furthermore, the residues in the first year were slightly higher than in the second year. The information obtained by the multivariate statistical analysis PLS-DA allowed for the determination of samples based on field site and varying habitat types (rocky reef, and Posidonia seabed). The results of this study showed that Posidonia sea urchins are contaminated by high molecular weight PAHs and that Capitana samples are more contaminated due to a higher level of human activity in the area.
اظهر المزيد [+] اقل [-]Vertical distribution of 241Pu in the southern Baltic Sea sediments النص الكامل
2014
Strumińska-Parulska, Dagmara I.
The vertical distribution of plutonium 241Pu in marine sediments can assist in determining the deposition history and sedimentation process of analyzed regions. In addition, 241Pu/239+240Pu activity ratio could be used as a sensitive fingerprint for radioactive source identification. The present preliminary studies on vertical distribution of 241Pu in sediments from four regions of the southern Baltic Sea are presented. The distribution of 241Pu was not uniform and depended on sediment geomorphology and depth as well as location. The highest concentrations of plutonium were found in the surface layers of all analyzed sediments and originated from the Chernobyl accident.
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