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Factors driving the seasonal distribution of zooplankton in a eutrophicated Mediterranean Lagoon Texte intégral
2015
Ziadi, Boutheina | Dhib, Amel | Turki, Souad | Aleya, Lotfi
The distribution of the zooplankton community was studied along with environmental factors at five sampling stations in Ghar El Melh Lagoon (GML) (Mediterranean Sea, northern Tunisia). GML is characterized by specific following properties: broad and shallow, freshwater supply (Station 1); connection to the sea (S2); stagnation (S3 especially), and eutrophic conditions with enhanced nutrient concentrations (S4 and S5). Samples were taken twice monthly from February 2011 to January 2012. Twenty-three zooplankton groups comprising 10 larval stages were identified. Zooplankton assemblages were largely dominated by copepods (37.25%), followed respectively by ciliates (21.09%), bivalve larvae (14.88%) and gastropod veligers (12.53%). Redundancy analysis indicated that while no significant difference was found in the distribution of zooplankton at any station, a strong difference was observed according to season. Both temporal and physicochemical fluctuations explain more than 50% of changes in zooplankton abundances.
Afficher plus [+] Moins [-]Influence of anthropogenic activities on PAHs in sediments in a significant gulf of low-latitude developing regions, the Beibu Gulf, South China Sea: Distribution, sources, inventory and probability risk Texte intégral
2015
Li, Pingyang | Xue, Rui | Wang, Yinghui | Zhang, Ruijie | Zhang, Gan
Fifteen polycyclic aromatic hydrocarbons (PAHs) in 41 surface sediment samples and a sediment core (50cm) from the Beibu Gulf, a significant low-latitude developing gulf, were analyzed. PAHs concentrations were 3.01–388ngg−1 (mean 95.5ngg−1) in the surface sediments and 10.5–87.1ngg−1 (average 41.1ngg−1) in the sediment core. Source apportionment indicated that PAHs were generated from coke production and vehicular emissions (39.4%), coal and biomass combustion (35.8%), and petrogenic sources (24.8%). PAHs were mainly concentrated in the industrialized and urbanized regions and the harbor, and were transported by atmospheric deposition to the marine matrix. The mass inventory (1.57–2.62t) and probability risk showed sediments here served as an important reservoir but low PAH risk. Different from oil and natural gas in developed regions, coal combustion has always been a significant energy consumption pattern in this developing region for the past 30years (56±5%).
Afficher plus [+] Moins [-]Indoor environmental quality in chemistry and chemical engineering laboratories at Izmir Institute of Technology Texte intégral
2015
Indoor air pollution in university research laboratories may be important to building occupants, especially for those who work in the laboratories. In this study, indoor air quality (IAQ) and indoor environmental comfort were investigated in research laboratories of two departments at a university. PM2.5, PM10, TVOC (total volatile organic compounds), and CO concentrations, and three comfort variables which are temperature, relative humidity, and CO2 were measured. PM2.5 concentration was determined gravimetrically by collecting particles on glass fiber filters, whereas the remaining pollutants and comfort variables were measured using a monitoring device. IAQ measurements showed that levels of all pollutants were under the limits in both of the departments except for TVOC in one laboratory which had a mean concentration of 182ppb. The comfort variables were in the comfort ranges for laboratories in both of the departments except for temperature in one laboratory with a mean value of 30 °C. In conclusion, measures are needed for extensive uses of organic solvents because ventilation may not be sufficient to keep VOC concentrations within the limits, and to provide thermal comfort.
Afficher plus [+] Moins [-]Source apportionment of carbonaceous fine particulate matter (PM2.5) in two contrasting cities across the Indo–Gangetic Plain Texte intégral
2015
Villalobos, Ana M. | Amonov, Mansur O. | Shafer, Martin M. | Devi, J Jai | Gupta, Tarun | Tripathi, Sachi N. | Rana, Kushal S. | McKenzie, Michael | Bergin, Mike H. | Schauer, James J.
Agra and Kanpur are heavily polluted Indian cities and are the fourth and second largest cities in Uttar Pradesh State, respectively. PM2.5 was collected from December 2011 to May 2012 in Agra and from December 2011 to October 2012 in Kanpur every 6th day. The samples were chemically analyzed to determine organic carbon (OC), water soluble organic carbon (WSOC), elemental carbon (EC), secondary inorganic ions, and particle–phase organic compounds. A chemical mass balance (CMB) receptor model using organic tracers was used to estimate source contributions to PM2.5. Concentrations of carbonaceous aerosols were on average 23±16μg/m3 in Agra and 33±21μg/m3 in Kanpur during the winter and summer periods, and had a strong seasonal trend with highest levels in winter (December–February) and then decreasing to summer (March–May). Five primary sources were identified. In Agra, biomass burning was the major source of OC in the winter months with decreasing relative and absolute concentrations in summer. In Kanpur, biomass burning was also the most important primary source of OC, but was about half the concentration found in Agra. Mobile source contributions to OC were on average 25±9% and 25±22% in Agra and Kanpur, respectively, with similar absolute concentrations of 2.5±1.9μg/m3 in most months. Secondary organic aerosol (SOA) was estimated from non–biomass burning WSOC and the unapportioned OC, with each method indicating SOA as a major source of OC in the winter in both cities, apportioning 25% of OC in Agra and 65% in Kanpur. SOA in Kanpur in December was four times higher than in Agra. Overall, results suggest differences in aerosol chemical composition and sources at these two sites across the Indo–Gangetic plain with biomass burning making up a larger fraction of the particulate OC in Agra, and SOA being a more important contributor to OC mass in Kanpur.
Afficher plus [+] Moins [-]Introduction of the alien Xenostrobus securis (Bivalvia: Mytilidae) into Hong Kong, China: Interactions with and impacts upon native species and the earlier introduced Mytilopsis sallei (Bivalvia: Dreissenidae) Texte intégral
2015
Morton, Brian | Leung, K.F.
This constitutes the first record of the Australian alien mytilid Xenostrobus securis in China. The introduction occurred prior to 2010 probably via shipping arriving at Yantian in Mirs Bay, China, close to Hong Kong. Point sources of infection could be Australia or Korea or Japan where it has similarly been introduced. Analysis of X. securis in Hong Kong shows that it tolerates a wide range of salinities from 5.4‰ to 28.7‰. Water temperatures in Hong Kong match those in its native range.In Hong Kong, X. securis co-occurs with the similarly introduced Mytilopsis sallei and a native bivalve community. The population structure of X. securis suggests a lifespan of >2years with new generations produced by conspecifics. Such a life history strategy is also exhibited by M. sallei. Now established in China, northern Asia, the Mediterranean and, most recently, the Iberian Atlantic, the invasion of other locations by X. securis seems probable.
Afficher plus [+] Moins [-]Backwash process of marine macroplastics from a beach by nearshore currents around a submerged breakwater Texte intégral
2015
Kataoka, Tomoya | Hinata, Hirofumi | Kato, Shigeru
A key factor for determining the residence time of macroplastics on a beach is the process by which the plastics are backwashed offshore (backwash process). Here, we deduced the backwash process of plastic fishing floats on Wadahama Beach based on the analysis of two-year mark-recapture experiments as well as nearshore current structures revealed by sequential images taken by za webcam installed at the edge of a cliff behind the beach. The analysis results revealed the occurrence of a combination of offshore currents and convergence of alongshore currents in the surf zone in storm events around a submerged breakwater off the northern part of the beach, where 48% of the backwashed floats were last found. We conclude that the majority of the floats on the beach were transported alongshore and tended to concentrate in the convergence zone, from where they were backwashed offshore by the nearshore currents generated in the events.
Afficher plus [+] Moins [-]Equilibrium passive sampling as a tool to study polycyclic aromatic hydrocarbons in Baltic Sea sediment pore-water systems Texte intégral
2015
Lang, Susann-Cathrin | Hursthouse, Andrew | Mayer, Philipp | Kötke, Danjiela | Hand, Ines | Schulz-Bull, Detlef | Witt, Gesine
Solid Phase Microextraction (SPME) was applied to provide the first large scale dataset of freely dissolved concentrations for 9 polycyclic aromatic hydrocarbons (PAHs) in Baltic Sea sediment cores. Polydimethylsiloxane (PDMS) coated glass fibers were used for ex-situ equilibrium sampling followed by automated thermal desorption and GC–MS analysis. From the PAH concentrations in the fiber coating we examined (i) spatially resolved freely dissolved PAH concentrations (Cfree); (ii) baseline toxicity potential on the basis of chemical activities (a); (iii) site specific mixture compositions; (iv) diffusion gradients at the sediment water interface and within the sediment cores and (v) site specific distribution ratios. Contamination levels were low in the northern Baltic Sea, moderate to elevated in the Baltic Proper and highest in the Gulf of Finland. Chemical activities were well below levels expected to cause narcosis to benthos organisms. The SPME method is a very sensitive tool that opens new possibilities for studying the PAHs at trace levels in marine environments.
Afficher plus [+] Moins [-]Participation in ICZM initiatives: Critical aspects and lessons learnt from the Mediterranean and Black Sea experiences Texte intégral
2015
Soriani, Stefano | Buono, Fabrizia | Tonino, Marco | Camuffo, Monica
Public participation is recognized as a necessary tool to ensure a successful implementation of Integrated Coastal Zone Management (ICZM) strategies and plans. This paper, based on the experiences carried out in the Mediterranean and in the Black Sea within the EU FP7 project PEGASO, presents some critical aspects and lessons learnt regarding participation in ICZM projects. The research shows that data availability, the complexity of data interpretation, an inadequate legal and cultural framework and the difficulties in promoting integration of all the components of coastal management within short term projects are all elements that if not properly considered since the beginning of the participatory process may hinder public participation effectiveness. Moreover the definition of the spatial scale of coastal phenomenon as well as the discrepancy between the local scale of coastal governance and the complex multi-scale nature of coastal systems remain highly critical aspects to be addressed.
Afficher plus [+] Moins [-]Bioassessment of marine sediment quality using meiofaunal assemblages in a semi-enclosed bay Texte intégral
2015
Liu, Xiaoshou | Huang, Deming | Zhu, Yanmei | Chang, Tianyi | Liu, Qinghe | Huang, Li | Zhao, Wei | Lin, Kuixuan | Liu, Lusan
In order to assess marine sediment quality of a semi-enclosed bay, sediment and meiofaunal samples were analyzed at 35 stations in coastal waters of Bohai Bay, China. Concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, Co and Mn) in sediment were measured and the Hakanson potential ecological risk index coupled with the ratio of nematodes to copepods (N/C ratio) was used. Results showed that the concentration of Mn was the highest while Cd was the main risk contributor. The Hakanson potential ecological risk index indicated that all pollutants posed low risks in the study area. However, the N/C ratio exhibited different results compared with Hakanson potential ecological risk index. BIOENV analysis identified the concentration of Ni and sediment grain size as the most important environmental variables influencing meiofaunal assemblages. The present study indicated that, in marine sediment quality assessments, meiofaunal assemblages should be involved besides pollutant concentrations.
Afficher plus [+] Moins [-]The assessment of the spatial and seasonal variability of chromophoric dissolved organic matter in the Southern Yellow Sea and the East China Sea Texte intégral
2015
Su, Rongguo | Bai, Ying | Zhang, Chuansong | Shi, Xiaoyong
Samples of chromophoric dissolved organic matter (CDOM) from the Southern Yellow Sea (SYS) and the East China Sea (ECS) were evaluated by fluorescent Excitation Emission Matrix (EEM) combined with Parallel Factorial Analysis (PARAFAC). Three terrestrial humic-like components (C1, C2 and C3) and one autochthonous protein-like component (C4) were identified. As for seasonal variations, CDOM displayed the following order on the whole: summer>spring>autumn. The C1, C2 and C3 components were mainly dominated by terrestrial inputs and their spatial distributions and temporal variations also can be influenced by primary productivity of phytoplankton, microbial activities and photobleaching. C4 was produced by phytoplankton and microorganisms and consumed by marine bacteria, and besides its distribution was attributed to the influence of riverine inputs. Terrestrial inputs were the dominant sources of CDOM in the SYS and ECS.
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