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Effect of air velocity on nanoparticles dispersion in the wake of a vehicle model: Wind tunnel experiments
2015
Mehel, Amine | Murzyn, Frederic
Exposure to nanoparticles coming from road–traffic concerns a large part of urban population in both outdoor and indoor environments leading to the enhancement of short and long–term health problems. The dynamics of such small particles is very sensitive to the turbulent diffusion and Brownian motion. Hence their concentrations are dependent on the flow structure properties (length and time scales). In this paper, a wind tunnel study is conducted to assess the effect of the flow on the dispersion of nanoparticles coming out from tailpipe in the near–wake of a reduced–scale truck model. Particle number concentration (PNC) measurements are achieved at 66 positions downstream of the model. Our results point out that the interaction of the ultrafine particles (UFP) with the vortices appearing in the near-wake of a truck enhances their dispersion in both transversal and vertical directions. Increasing the inflow air velocity strengthens this spreading. Overall, we demonstrate that such wind tunnel measurements are fundamental to improve our knowledge on the existing interaction between road–traffic, turbulence and particle concentration to accurately evaluate human exposure rates to ultrafine particles and their potential consequences.
Mostrar más [+] Menos [-]Short-term dynamics of cyanobacterial toxins (microcystins) following a discharge from a coastal reservoir in Isahaya Bay, Japan
2015
Umehara, Akira | Komorita, Tomohiro | Tai, Akira | Takahashi, Tohru | Orita, Ryo | Tsutsumi, Hiroaki
Freshwater cyanobacteria produce highly toxic substances such as microcystins (MCs), and water containing MCs is often discharged to downstream and coastal areas. We conducted field monitoring in Isahaya Bay to clarify the short-term dynamics of MCs discharged from a reservoir following a cyanobacteria bloom in the warm season. MCs were detected in the seawater of the bay (max. 0.10μgL−1), and were deposited on the sea floor, with the MC content of the surface sediment increasing by approximately five times (0.11±0.077–0.53±0.15μgkgww−1, mean±SD) at the four stations near the reservoir drainage gate before and after the discharge. The MCs was then transported from the mouth of the bay by tidal currents during the period of the study. Therefore, the MCs were moved away from the closed water area where the cyanobacteria blooms, and spread throughout the coastal area.
Mostrar más [+] Menos [-]Metabarcoding approach for the ballast water surveillance – An advantageous solution or an awkward challenge?
2015
Zaiko, Anastasija | Martinez, Jose L. | Schmidt-Petersen, Julia | Ribicic, Deni | Samuiloviene, Aurelija | García Vázquez, Eva
Transfer of organisms with ships’ ballast water is recognized as a major pathway of non-indigenous species introduction and addressed in a few recent legislative initiatives. Among other they imply scientific and technical research and monitoring to be conducted in a efficient and reliable way. The recent development of DNA barcoding and metabarcoding technologies opens new opportunities for biodiversity and biosecurity surveillance. In the current study, the performance of metabarcoding approach was assessed in comparison to the conventional (visual) observations, during the en route experimental ballast water survey. Opportunities and limitations of the molecular method were identified from taxonomical datasets rendered by two molecular markers of different degree of universality – the universal cytochrome oxydase sub-unit I gene and a fragment of RuBisCO gene. The cost-efficacy and possible improvements of these methods are discussed for the further successful development and implementation of the approach in ballast water control and NIS surveillance.
Mostrar más [+] Menos [-]Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea
2015
Cho, Jinhyung | Hyun, Sangmin | Han, J.-H. | Kim, Suhyun | Shin, Dong-Hyeok
The spatiotemporal distribution and their mass accumulation rate (MAR) of heavy metals were investigated to evaluate the time-dependent historical trends of heavy metal concentration. The three short cores used for this study were collected from the catchment area (MS-PC5, 60cm length), the central part (MS-PC4, 40cm length) and the offshore (MS-PC2, 60cm length) of the Masan Bay, Korea. The concentration of heavy metals (Co, Ni, Cu, Zn, Cr and Pb) in catchment area is as much as 1.5–2 times higher than central part of the Bay, and about 2 times higher than offshore area approximately. In particular, MAR of metals (Cu, Zn and Pb) show clear spatiotemporal variation, so that MAR’s of heavy metal may provide more accurate information in evaluating the degree of pollution. Temporally, the heavy metal concentration had been increased since the late 1970s, but it seems to decrease again since the 2004yr in catchment area. This may came from concentrated efforts for the government to reduce industrial waste release.
Mostrar más [+] Menos [-]Spatial distribution and transport patterns of NO2 in the Tijuana – San Diego area
2015
Rivera, Claudia | Stremme, Wolfgang | Barrera, Hugo | Friedrich, Martina M. | Grutter, Michel | Garcia–Yee, Jose | Torres–Jardon, Ricardo | Ruiz–Suarez, Luis Gerardo
The atmospheric composition of the San Diego – Tijuana border is affected by transport of air pollutants between both regions and in both directions. In this study we show NO2 transport events identified during Cal–Mex 2010 field experiment at two different ground sites, located one downwind of the other. This field campaign was designed to overlap with the closing weeks of CalNex project to observe trans–boundary pollution transport in this area. The measurements showed a clear dispersion pattern of NO2 towards the east–southeast on several occasions during the field experiment. Additionally, the NO2 column distribution above the Tijuana – San Diego region was reconstructed from the OMI satellite data product, and a cluster analysis with the corresponding meteorological data was performed to identify four distinct wind patterns yielding different NO2 distribution maps and detecting dominant wind patterns in this region, either towards the E–SE or E–NE approximately 86% of the time.
Mostrar más [+] Menos [-]Evaluating the potential of ecological niche modelling as a component in marine non-indigenous species risk assessments
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.
Mostrar más [+] Menos [-]Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally
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.
Mostrar más [+] Menos [-]Integrated use of biomarkers and condition indices in mussels (Mytilus galloprovincialis) for monitoring pollution and development of biomarker index to assess the potential toxic of coastal sites
2015
Benali, Imene | Boutiba, Zitouni | Merabet, Amina | Chèvre, Nathalie
In this study, we are interested in spatial and temporal variations of the biological and physiological responses of mussels collected from contrasting marine sites regarding their levels of pollution. We measured both the conditions indices and the enzymatic biomarker expression: acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) activity. The enzymatic biomarkers were chosen because they respond to environmental stress. Results show a significant interactions between biomarker variations and conditions indices in the industrial harbor site throughout the seasons. But no significant changes in the reference site. Furthermore, we classified the sites along the seasons according to their potential ecotoxicity, calculated based on the sum of the normalised values of the biomarkers. The results show a very high biomarker index in the impacted site with irregular changes between seasons. This biomarker index is therefore a valuable tool that could be used to classify the toxic potential of coastal sites.
Mostrar más [+] Menos [-]Stable isotope analysis of a newly established macrofaunal food web 1.5years after the Hebei Spirit oil spill
2015
Han, Eunah | Park, Hyun Je | Bergamino, Leandro | Choi, Kwang-Sik | Choy, Eun Jung | Yu, Ok Hwan | Lee, Tae-won | Park, Heung-Sik | Shim, Won Joon | Kang, Chang-Keun
We examined trophic relationships in a newly established community 1.5years after the Hebei Spirit oil spill on the west coast of Korea. Carbon and nitrogen stable isotope ratios in consumers and their potential food sources were compared between the oil-spill site and reference site, located 13.5km from the oil-spill spot. The isotopic mixing model and a novel circular statistics rejected the influx of petrogenic carbon into the community and identified spatial consistencies such as the high contributions of microphytobenthos, food-chain length, and the isotopic niche of each feeding guild between sites. We suggested that high level of trophic plasticity and the prevalence of omnivory of consumers may promote the robustness of food web against the oil contamination. Furthermore, we highlighted the need of holistic approaches including different functional groups to quantify changes in the food web structure and assess the influence of different perturbations including oil spill.
Mostrar más [+] Menos [-]An eight year (2005–2013) temporal trend of halogenated organic pollutants in fish from the Pearl River Estuary, South China
2015
Sun, Run-Xia | Luo, Xiao-Jun | Tan, Xiao-Xin | Tang, Bin | Li, Zong-Rui | Mai, Bi-Xian
Dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), 2,3,5,6-tetrabromo-p-xylene (pTBX) and pentabromotoluene (PBT) were measured in baby croaker (Collichthys lucidus) and mullet (Osteomugil ophuyseni) collected in 2005 and 2013 from the Pearl River Estuary. DDTs, HCHs, PCBs, and PBDEs were detected in two fish species at concentrations of 150–8100, 1.4–120, 22–560, 2.2–280ng/g lipid wt., respectively. The levels of these chemicals were significantly lower in 2013 than in 2005. The compositions for DDTs, HCHs, and PBDEs in 2013 differed from those in 2005, indicating source changes between the two sampling periods. DP, pTBX and PBT were detected at concentrations of ND–130ng/g lipid wt. No clear temporal trends were found for these contaminants. Overall, these results indicated the effectiveness of regulations and source controls in substantively reducing inputs of these contaminants to the Pearl River Estuary.
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