Affiner votre recherche
Résultats 981-990 de 3,207
Monosaccharide anhydrides, monocarboxylic acids and OC/EC in PM1 aerosols in urban areas in the Czech Republic Texte intégral
2015
Křůmal, Kamil | Mikuška, Pavel | Večeřa, Zbyněk
The concentrations of monosaccharide anhydrides (levoglucosan, mannosan, galactosan), monocarboxylic acids (alkanoic acids C7 – C20 and two unsaturated fatty acids, palmitoleic and oleic acids) and organic and elemental carbon in PM1 aerosol samples were measured in two cities of the Czech Republic (Brno and Šlapanice) in winter and summer seasons of 2009 and 2010.Mass concentrations of PM1 aerosols (determined by weighing filters with collected aerosol) were higher in winter than in summer in both 2009 and 2010, in Brno as well as in Šlapanice.Organic compounds were analysed by GC–MS. The sum of average atmospheric concentration of monosaccharide anhydrides (MAs) in PM1 aerosol in Brno and Šlapanice was 273 and 646 ng m−3 in winter and 20–42 ng m−3 in summer. The higher concentrations of MAs in PM1 aerosols in winter seasons indicate higher frequency of biomass combustion than in summer seasons. Levoglucosan was the most abundant monosaccharide anhydride. Contrary to MAs, the concentrations of majority monocarboxylic acids were higher in summer (153–221 ng m−3) than in winter (116–206 ng m−3) in both cities in 2009 and in 2010. Palmitic acid was the most abundant monocarboxylic acid.The concentrations of both organic (OC) and elemental (EC) carbon were higher in winter than in summer, which corresponds especially to higher biomass burning and coal combustion in the frame of residential heating within winter seasons. Mass concentrations of the analysed aerosol samples were counted, i.e., OCBB and ECBB (biomass burning), OCFF and ECFF (fossil fuel combustion), and OCBIO (biogenic sources).Higher concentrations of MAs and PM1, OC and EC in winter seasons, could be caused not only by larger emissions from biomass or coal combustion, but also by less dispersion due to different atmospheric conditions.
Afficher plus [+] Moins [-]East Asian seas: A hot spot of pelagic microplastics Texte intégral
2015
Isobe, Atsuhiko | Uchida, Keiichi | Tokai, Tadashi | Iwasaki, Shinsuke
To investigate concentrations of pelagic micro- (<5mm in size) and mesoplastics (>5mm) in the East Asian seas around Japan, field surveys using two vessels were conducted concurrently in summer 2014. The total particle count (pieceskm−2) was computed based on observed concentrations (piecesm−3) of small plastic fragments (both micro- and mesoplastics) collected using neuston nets. The total particle count of microplastics within the study area was 1,720,000pieceskm−2, 16 times greater than in the North Pacific and 27 times greater than in the world oceans. The proportion of mesoplastics increased upstream of the northeastward ocean currents, such that the small plastic fragments collected in the present surveys were considered to have originated in the Yellow Sea and East China Sea southwest of the study area.
Afficher plus [+] Moins [-]Characterization of marine aerosols and precipitation through shipboard observations on the transect between 31° N–32° S in the West Pacific Texte intégral
2015
Xu, Guojie | Gao, Yuan
To characterize the chemical composition, size distributions, and fractional Fe solubility of atmospheric particles over Asian marginal seas, South Indian Ocean and Australian coast, selected water–soluble inorganic and organic species in aerosols and precipitation, trace metals and soluble Fe in aerosols were analyzed by multi–instruments. Results showed that sea salt and non–sea–salt sulfate (nss–SO42–) were the main components in aerosols. Over Asian marginal seas, Cl– and Na+ were the dominant ions in precipitation, accounting for ˜;72% of the total ions. Both SO42– and NO3– accounted for −26% of the total anions, controlling the acidity of the precipitation. Non–sea–salt Ca2+ (nss–Ca2+) accounted for 6.9% of the total cations, dominating the neutralizing component in rainwater. Observed methane sulfonate (MSA) concentrations and MSA/nss–SO42– increased southward. The concentrations of sea salt were affected by wind speeds, which was mainly accumulated in particle size >10μm. Particle size distributions of nss–SO42– and NH4+ mainly peaked in the fine mode, while NO3– was mainly accumulated in the coarse mode. Oxalate presented a bimodal size distribution pattern in both fine and coarse modes. Based on the air mass back trajectories, enrichment factors and Fe/Al, V/Al ratios, aerosol samples collected over Asian marginal seas could be affected by both long–range transported dust and anthropogenic emissions. Good relationship was found between total dissolved iron and nss–SO42–, indicating that acid processing during long–range transport could play an important role in fractional iron solubility in aerosols. The inverse relationship between atmospheric total Fe and fractional Fe solubility fitted in the global–scale trend. This study implicates that dust and acidic air pollutants from continental sources can interact and affect iron solubility in aerosols in the marine atmosphere. However, due to the small size of samples in this study, more investigations need to be conducted in future.
Afficher plus [+] Moins [-]Speciation and risk of heavy metals in sediments and human health implications of heavy metals in edible nekton in Beibu Gulf, China: A case study of Qinzhou Bay Texte intégral
2015
Gu, Yang-Guang | Lin, Qin | Yu, Zi-Ling | Wang, Xu-Nuo | Ke, Chang-Liang | Ning, Jia-Jia
We investigated the total concentrations of heavy metals in surface sediments and nekton, along with sediment metal chemical partitioning in Qinzhou Bay of the Beibu Gulf. Cd was preferentially associated with the acid-soluble fraction and Pb mainly with the reducible fraction, whereas a major portion of Cr, Ni, Cu, and Zn was strongly associated with the residual fractions. A principal component analysis (PCA) in sediment metal speciation revealed three groupings (Cd; Pb; Cr, Ni, Cu, and Zn) that mainly resulted from different distributions of the metals in the various fractions. The Cr concentrations in nekton species were higher than maximum Cr concentrations permitted by the Chinese National Standard (GB 2762-2012). Taking as a whole, surface sediments of Qinzhou Bay had a 21% incidence calculation of adverse biological effects, based on the mean probable-effects-levels quotient. A human health risk assessment indicated no significant adverse health effects from consumption of nekton.
Afficher plus [+] Moins [-]Flow cytometric applicability to evaluate UV inactivation of phytoplankton in marine water samples Texte intégral
2015
Olsen, Ranveig Ottoey | Hess-Erga, Ole-Kristian | Larsen, Aud | Thuestad, Gunnar | Tobiesen, August | Hoell, Ingunn Alne
Disinfection of microbes is of importance to prevent the spread of pathogens and non-indigenous species in the environment. Here we test the applicability of using flow cytometry (FCM) to evaluate inactivation of the phytoplankter Tetraselmis suecica after UV irradiation and labeling with the esterase substrate 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM). Non-irradiated and UV irradiated samples were analyzed with the plate count technique and FCM for 24days. The numbers of colony forming units were used as a standard to develop a FCM protocol. Our protocol readily distinguishes live and dead cells, but challenges were encountered when determining whether UV damaged cells are dying or repairable. As damaged cells can represent a risk to aquatic organisms and/or humans, this was taken into account when developing the FCM protocol. In spite of the above mentioned challenges we argue that FCM represents an accurate and rapid method to analyze T. suecica samples.
Afficher plus [+] Moins [-]Hydrophobic poly(alkoxysilane) organogels as sorbent material for oil spill cleanup Texte intégral
2015
Ozan Aydin, Gulsah | Bulbul Sonmez, Hayal
In this study, reusable poly(alkoxysilane) organogels with high absorption capacities were synthesized by the condensation of a cyclo aliphatic glycol (UNOXOL™) and altering the chain length of the alkyltriethoxysilanes. The structural and thermal properties of cross-linked poly(alkoxysilane) polymers were determined by FTIR, solid-state 13C and 29Si CPMAS NMR and TGA. The oil absorbency of poly(alkoxysilane)s was determined through oil absorption tests, absorption and desorption kinetics. Results showed that the highest oil absorbency capacities were found to be 295% for hexane, 389% for euro diesel, 428% for crude oil, 652% for gasoline, 792% for benzene, 792% for toluene, 868% for tetrahydrofuran, and 1060% for dichloromethane for the poly(alkoxysilane) gels based on UNOXOL™ and dodecyltriethoxysilane. Owing to their hydrophobic structure, the poly(alkoxysilane) organogels can selectively absorb crude oil from water. The reusability of the absorbents was quantitatively investigated, demonstrating that absorbents can be used effectively at least nine times.
Afficher plus [+] Moins [-]Sand patties provide evidence for the presence of Deepwater Horizon oil on the beaches of the West Florida Shelf Texte intégral
2015
McDaniel, L.D. | Basso, J. | Pulster, E. | Paul, J.H.
The ecological consequences of the Deepwater Horizon (DWH) oil spill are both long-term and pervasive. The distribution of toxicity and mutagenicity in the Gulf of Mexico suggests oil from the DWH spill could have contaminated the West Florida Shelf (WFS). We utilized polycyclic aromatic hydrocarbon (PAH) analysis to determine presence and potential origin of oil contaminants in beach sand patty samples. PAH profiles from WFS beaches were statistically significantly similar to DWH contaminated samples from the Northeast Gulf of Mexico (Gulf Shores, AL; Ft. Pickens, FL). Dioctyl sodium sulfosuccinate (DOSS), a major component of Corexit 9500 dispersant was also detected in the sediments. DOSS concentrations ranged from 1.6 to 5.5ngg−1 dry weight. Additionally, two samples from DWH oil contaminated beaches were acutely toxic and one WFS beach sediment sample was mutagenic. These observations provide support for the theory that DWH oil made its way onto beaches of the WFS.
Afficher plus [+] Moins [-]Evaluating the potential of ecological niche modelling as a component in marine non-indigenous species risk assessments Texte intégral
2015
Leidenberger, Sonja | Obst, Matthias | Kulawik, Robert | Stelzer, Kerstin | Heyer, Karin | Hardisty, Alex | Bourlat, Sarah J.
Marine biological invasions have increased with the development of global trading, causing the homogenization of communities and the decline of biodiversity. A main vector is ballast water exchange from shipping. This study evaluates the use of ecological niche modelling (ENM) to predict the spread of 18 non-indigenous species (NIS) along shipping routes and their potential habitat suitability (hot/cold spots) in the Baltic Sea and Northeast Atlantic. Results show that, contrary to current risk assessment methods, temperature and sea ice concentration determine habitat suitability for 61% of species, rather than salinity (11%). We show high habitat suitability for NIS in the Skagerrak and Kattegat, a transitional area for NIS entering or leaving the Baltic Sea. As many cases of NIS introduction in the marine environment are associated with shipping pathways, we explore how ENM can be used to provide valuable information on the potential spread of NIS for ballast water risk assessment.
Afficher plus [+] Moins [-]The risk assessment of heavy metals in Futian mangrove forest sediment in Shenzhen Bay (South China) based on SEM–AVS analysis Texte intégral
2015
Chai, Minwei | Shen, Xiaoxue | Li, Ruili | Qiu, Guoyu
The risks of heavy metal in Futian mangrove forest sediment were assessed using the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) methods. The results indicated that AVS distributions were more variable than the SEM distributions at all 16 sampling sites. The positive correlation between AVS and SEM indicated that their similar formative and existing conditions and that AVS acted as an important carrier for SEM. The major SEM component was Zn (69.7.3–94.2%), whereas the Cd contribution (the most toxic metal present) to SEM was no more than 1%. The possible adverse effects caused by heavy metals at ten sampling sites may be due to higher levels of SEMs, rather than AVSs. The total organic carbon (TOC) was an important metal-binding phase in the sediments. Taking into account the TOC concentration, there were no adverse effects due to heavy metals in any of the Futian mangrove forest sediments.
Afficher plus [+] Moins [-]Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally Texte intégral
2015
Ramirez-Llodra, Eva | Trannum, Hilde C. | Evenset, Anita | Levin, Lisa A. | Andersson, Malin | Finne, Tor Erik | Hilario, Ana | Flem, Belinda | Christensen, Guttorm | Schaanning, Morten | Vanreusel, Ann
Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally Texte intégral
2015
Ramirez-Llodra, Eva | Trannum, Hilde C. | Evenset, Anita | Levin, Lisa A. | Andersson, Malin | Finne, Tor Erik | Hilario, Ana | Flem, Belinda | Christensen, Guttorm | Schaanning, Morten | Vanreusel, Ann
The mining sector is growing in parallel with societal demands for minerals. One of the most important environmental issues and economic burdens of industrial mining on land is the safe storage of the vast amounts of waste produced. Traditionally, tailings have been stored in land dams, but the lack of land availability, potential risk of dam failure and topography in coastal areas in certain countries results in increasing disposal of tailings into marine systems. This review describes the different submarine tailing disposal methods used in the world in general and in Norway in particular, their impact on the environment (e.g. hyper-sedimentation, toxicity, processes related to changes in grain shape and size, turbidity), current legislation and need for future research. Understanding these impacts on the habitat and biota is essential to assess potential ecosystem changes and to develop best available techniques and robust management plans.
Afficher plus [+] Moins [-]Submarine and deep-sea mine tailing placements: a review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally Texte intégral
1000 | 2015
Ramirez-Llodra, Eva | Trannum, Hilde C. | Evenset, Anita | Levin, Lisa A. | Andersson, Malin | Finne, Tor Erik | Hilario, Ana | Flem, Belinda | Christensen, Guttorm | Schaanning, Morten | Vanreusel, Ann
The mining sector is growing in parallel with societal demands for minerals. One of the most important environmental issues and economic burdens of industrial mining on land is the safe storage of the vast amounts of waste produced. Traditionally, tailings have been stored in land dams, but the lack of land availability, potential risk of dam failure and topography in coastal areas in certain countries results in increasing disposal of tailings into marine systems. This review describes the different submarine tailing disposal methods used in the world in general and in Norway in particular, their impact on the environment (e.g. hyper-sedimentation, toxicity, processes related to changes in grain shape and size, turbidity), current legislation and need for future research. Understanding these impacts on the habitat and biota is essential to assess potential ecosystem changes and to develop best available techniques and robust management plans.
Afficher plus [+] Moins [-]