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Recent trends in tropospheric NO2 over India observed by SCIAMACHY: Identification of hot spots Texte intégral
2013
Ramachandran, Arya | Jain, Nayan K. | Sharma, Shashikant A. | Pallipad, Jayaprasad
Satellite remote sensing technology has a great potential to measure the properties of atmosphere and has shown marked advancements through the last decade, in monitoring nitrogen oxide species (NOX) in troposphere. NO2 in troposphere is one of the key factors which determine the air quality and has serious implications on human health and plant growth. It is also well known for its indirect contribution to climate change. The identification of spatial and temporal variations of NO2 is necessary for any effective mitigation plan to curb its obnoxious abundance. Tropospheric NO2 measurements provided by the satellite remote sensor “SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY” (SCIAMACHY) are utilized here to identify the regions across India where a concentration of NO2 exceeds the permissible healthy level. A new approach based on empirical approximation is attempted to normalize the unit of satellite measurement with the unit of existing air quality standard. Trend analysis for all the regions are carried out by means of a non–linear regression method. The geospatial and statistical analysis of monthly tropospheric NO2 data from the full operational period of SCIAMACHY (2002 August–2012 March) have resulted in the identification of 12 hot spot regions across India among which most of them exhibited a significant increasing trend. Some of the rural districts which were not previously implicated for NO2 pollution risk are also recognized here. This study illustrates the possibility of the use of satellite measurements in air quality monitoring and management in regional spatial scale. The effects of seasonal climatic changes in India on the ambient NO2 pollution level are also explained.
Afficher plus [+] Moins [-]Analysis of a beach as a time-invariant linear input/output system of marine litter Texte intégral
2013
Kataoka, Tomoya | Hinata, Hirofumi | Kato, Shigeru
The exponential decay of the amount of new litter on Wadahama Beach, Nii-jima Island, Japan revealed by 20-month mark-recapture experiments demonstrates a linear response of the beach to the input of target items. Here we show the amplitude and phase characteristics of the beach as a time-invariant linear input/output system and discuss the hydrodynamic and geomorphological factors that would determine the characteristics with the aid of a diffusion equation. The characteristics are fully determined by the residence time of the items (τr=209days) and can be described as functions of the ratio of τr to the period of input variability. The decay is reproduced well by the analytical solution of the equation with a constant diffusion coefficient (D), whose order was estimated by τr and the backshore width. Generally, D would depend on hydrodynamical statistics and beach geomorphology as well as the dimensions and density of the items.
Afficher plus [+] Moins [-]Distributions, possible sources and biological risk of DDTs, HCHs and chlordanes in sediments of Beibu Gulf and its tributary rivers, China Texte intégral
2013
Xu, Yiyin | Wang, Yinghui | Li, Jun | Liu, Xiang | Zhang, Ruijie | Guo, Songjun | Huang, Wenyu | Zhang, Gan
Thirty-five surface sediment samples collected from Beibu Gulf and its tributary rivers, China were analyzed for DDTs, HCHs and chlordanes. Total concentrations of DDTs, HCHs and chlordanes in sediments ranged from 0.59 to 126ngg−1, ND to 2.65ngg−1 and 0.27 to 3.41ngg−1 based on dry weight (dw), respectively. Concentrations of DDTs were higher than those reported in the sediments from other regions of the world, while concentrations of HCHs and chlordanes were relatively low. High concentrations of DDTs were observed in the harbor region and aquaculture bases and high concentrations of HCHs were found in the Qin River Estuary. The ratios of (DDE+DDD)/DDTs reflected a mixed input of weathered and fresh DDTs. The predominant β-HCH indicated that HCHs in the study area mainly originated from the historical usage of technical HCH. The residues of DDTs would pose adverse biological effects on the study area.
Afficher plus [+] Moins [-]Dominant petroleum hydrocarbon-degrading bacteria in the Archipelago Sea in South-West Finland (Baltic Sea) belong to different taxonomic groups than hydrocarbon degraders in the oceans Texte intégral
2013
Reunamo, Anna | Riemann, Lasse | Leskinen, Piia | Jørgensen, Kirsten S.
The natural petroleum hydrocarbon degrading capacity of the Archipelago Sea water in S-W Finland was studied in a microcosm experiment. Pristine and previously oil exposed sites were examined. Bacterial community fingerprinting was performed using terminal restriction fragment length polymorphism (T-RFLP) and samples from selected microcosms were sequenced. The abundance of PAH degradation genes was measured by quantitative PCR. Bacterial communities in diesel exposed microcosms diverged from control microcosms during the experiment. Gram positive PAH degradation genes dominated at both sites in situ, whereas gram negative PAH degrading genes became enriched in diesel microcosms. The dominant bacterial groups after a 14 days of diesel exposure were different depending on the sampling site, belonging to the class Actinobacteria (32%) at a pristine site and Betaproteobacteria (52%) at a previously oil exposed site. The hydrocarbon degrading bacteria in the Baltic Sea differ from those in the oceans, where most hydrocarbon degraders belong to Gammaproteobacteria.
Afficher plus [+] Moins [-]Analysis of the bacterial community in the two typical intertidal sediments of Bohai Bay, China by pyrosequencing Texte intégral
2013
Wang, Liping | Liu, Lusan | Zheng, Binghui | Zhu, Yanzhong | Wang, Xing
For full understanding of the bacterial community in the intertidal zones of Bohai Bay, China, we used pyrosequencing-based approach to analyze the 16S rRNA gene of bacteria in the sediments from the two typically intertidal zones – Qikou (Qi) and Gaoshaling (Ga). Results showed that, at a 0.03 distance, the sequences from the Qi sediment were assigned to 3252 operational taxonomic units (OTUs) which belong to 34 phyla, 69 classes and 119 genera, while the 3740 OTUs from the Ga sediment were affiliated with 33 phyla, 66 classes and 146 genera. Comparing the bacterial communities inhabiting in the two intertidal sediments, we observed significant difference in the dominant composition and distribution at phylum, class and genus levels. Canonical correspondence analysis (CCA) showed that the median grain size and DO were the most important factors regulating the bacterial abundance and diversity, while the other environmental factors have effects with different degree.
Afficher plus [+] Moins [-]Marine debris removal: One year of effort by the Georgia Sea Turtle-Center-Marine Debris Initiative Texte intégral
2013
Martin, Jeannie Miller
Once in the marine environment, debris poses a significant threat to marine life that can be prevented through the help of citizen science. Marine debris is any manufactured item that enters the ocean regardless of source, commonly plastics, metal, wood, glass, foam, cloth, or rubber. Citizen science is an effective way to engage volunteers in conservation initiatives and provide education and skill development. The Georgia Sea Turtle Center Marine Debris Initiative (GSTC-MDI) is a grant funded program developed to engage citizens in the removal of marine debris from the beaches of Jekyll Island, GA, USA and the surrounding areas. During the first year of effort, more than 200 volunteers donated over 460h of service to the removal of marine debris. Of the debris removed, approximately 89% were plastics, with a significant portion being cigarette materials. Given the successful first year, the GSTC-MDI was funded again for a second year.
Afficher plus [+] Moins [-]Environmental fate of fungicides and other current-use pesticides in a central California estuary Texte intégral
2013
Smalling, Kelly L. | Kuivila, Kathryn M. | Orlando, James L. | Phillips, Bryn M. | Anderson, Brian S. | Siegler, Katie | Hunt, John W. | Hamilton, Mary
The current study documents the fate of current-use pesticides in an agriculturally-dominated central California coastal estuary by focusing on the occurrence in water, sediment and tissue of resident aquatic organisms. Three fungicides (azoxystrobin, boscalid, and pyraclostrobin), one herbicide (propyzamide) and two organophosphate insecticides (chlorpyrifos and diazinon) were detected frequently. Dissolved pesticide concentrations in the estuary corresponded to the timing of application while bed sediment pesticide concentrations correlated with the distance from potential sources. Fungicides and insecticides were detected frequently in fish and invertebrates collected near the mouth of the estuary and the contaminant profiles differed from the sediment and water collected. This is the first study to document the occurrence of many current-use pesticides, including fungicides, in tissue. Limited information is available on the uptake, accumulation and effects of current-use pesticides on non-target organisms. Additional data are needed to understand the impacts of pesticides, especially in small agriculturally-dominated estuaries.
Afficher plus [+] Moins [-]Assessment of cruise–ship activity influences on emissions, air quality, and visibility in Glacier Bay National Park Texte intégral
2013
Mölders, Nicole | Gende, Scott | Pirhalla, Michael
An activity–based emission model was developed to determine cruise–ship emissions. Calculated emissions depend on cruise–voyage data (position, cruise speed, operation mode) and the ships’ characteristics (engine power, size, fuel– type, maximum cruise–speed). Cruise–ship emissions of particulate matter (PM) and its precursors were determined for the 2008 cruise season and for two proposed management actions: a prescribed speed in Glacier Bay, and implementation of an Emission Control Area (ECA) in Alaska at–large. The Weather Research and Forecasting model inline coupled with chemistry served to assess the impact of these management actions on air quality and visibility. On season–average, ships emitted ~2.5 µg/m2/s PM in Glacier Bay. Cruising at constant 6.69m/s anywhere in Glacier Bay decreased PM–emissions by 32% and marginally increased mean visibility. Altered cruise speeds strongly changed the spatial emission and concentration distributions of all species in and up to 30 km downwind of Glacier Bay. Changes differed among species. An ECA reduced PM–emissions from cruise ships by 74% and their impacts on visibility by 0.1, 0.2 and 0.1 deciview for the 10%, 50% and 90%–percentiles of best–visibility–days in Glacier Bay.
Afficher plus [+] Moins [-]Chlorinated compounds and polybrominated diphenyl ethers (PBDEs) in mussels (Mytilus galloprovincialis) collected from Apulia Region coasts Texte intégral
2013
Giandomenico, Santina | Spada, Lucia | Annicchiarico, Cristina | Assennato, Giorgio | Cardellicchio, Nicola | Ungaro, Nicola | Leo, Antonella Di
This project was carried out to assess the levels and spatial distribution of organochlorine compounds in the coastal marine environment, using mussels as bioindicators to evaluate the coastal water quality. Levels of polychlorobiphenils (PCB), chlorinated pesticides (DDT isomers, HCH isomers, Aldrin, Dieldrin, alfa-Endosulfan, Hexachlorobenzene, Pentachlorobenzene) and polybrominated diphenyl ethers (PBDEs) were determined in tissues from mussels (Mytilus galloprovincialis) collected along the Apulia Region coasts (Mediterranean Sea). Results indicate that contamination by organochlorine compounds is higher in mussels sampled in the Ionian Sea than in those from the Adriatic Sea, with PCB levels up to seven times higher in mussels from Ionian than from the Adriatic Sea. Although PCB levels were above the maximum values indicated by both European Community (EC) and National regulation in several sample sites, the PCB concentrations were particularly high in some stations, suggesting that these locations require a much specific attention. Conversely, results on the mussel contamination by PBDEs highlight their ubiquitous environmental distribution, and underline the need to establish the maximum level for these compounds in foodstuff, according to European Regulations.
Afficher plus [+] Moins [-]Comparison of fate profiles of PAHs in soil, sediments and mangrove leaves after oil spills by QSAR and QSPR Texte intégral
2013
Tansel, Berrin | Lee, Mengshan | Tansel, Derya Z.
First order removal rates for 15 polyaromatic hydrocarbons (PAHs) in soil, sediments and mangrove leaves were compared in relation to the parameters used in fate transport analyses (i.e., octanol–water partition coefficient, organic carbon–water partition coefficient, solubility, diffusivity in water, HOMO–LUMO gap, molecular size, molecular aspect ratio). The quantitative structure activity relationships (QSAR) and quantitative structure property relationships (QSPR) showed that the rate of disappearance of PAHs is correlated with their diffusivities in water as well as molecular volumes in different media. Strong correlations for the rate of disappearance of PAHs in sediments could not be obtained in relation to most of the parameters evaluated. The analyses showed that the QSAR and QSPR correlations developed for removal rates of PAHs in soils would not be adequate for sediments and plant tissues.
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