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Dietary mercury exposure to endangered California Clapper Rails in San Francisco Bay Полный текст
2014
Casazza, Michael L. | Ricca, Mark A. | Overton, Cory T. | Takekawa, John Y. | Merritt, Angela M. | Ackerman, Joshua T.
California Clapper Rails (Rallus longirostris obsoletus) are an endangered waterbird that forage in tidal-marsh habitats that pose risks from mercury exposure. We analyzed total mercury (Hg) in six macro-invertebrate and one fish species representing Clapper Rail diets from four tidal-marshes in San Francisco Bay, California. Mercury concentrations among individual taxa ranged from lowest at Colma Creek (mean range: 0.09–0.2μg/gdw) to highest at Cogswell (0.2–0.7), Laumeister (0.2–0.9) and Arrowhead Marshes (0.3–1.9). These spatial patterns for Hg matched patterns reported previously in Clapper Rail blood from the same four marshes. Over 25% of eastern mudsnails (Ilyanassa obsolete) and staghorn sculpin (Leptocottus armatus) exceeded dietary Hg concentrations (ww) often associated with avian reproductive impairment. Our results indicate that Hg concentrations vary considerably among tidal-marshes and diet taxa, and Hg concentrations of prey may provide an appropriate proxy for relative exposure risk for Clapper Rails.
Показать больше [+] Меньше [-]Spatial distribution of organic and pyritic sulfur in surface sediments of eutrophic Jiaozhou Bay, China: Clues to anthropogenic impacts Полный текст
2014
Chen, Ke-Ke | Zhu, Mao-Xu | Yang, Gui-Peng | Fan, De-Jiang | Huang, Xiang-Li
Anthropogenic perturbations exert important impacts on sulfur geochemistry in marine sediments. In the study, chemical extraction was used to quantify four sulfur pools, i.e., pyrite, humic-acid sulfur (HA-S), fulvic-acid sulfur (FA-S), and residual organic sulfur (ROS), in surface sediments of eutrophic Jiaozhou Bay. Results show that riverine inputs are the main control on organic matter (OM) distribution in the sediments. OM enrichment in the eastern coast is mainly due to discharges of anthropogenic wastes. Spatial coupling of pyrite and FA-S vs. TOC points to the impacts of OM enrichment on formation and preservation of pyrite and FA-S. Poor spatial coupling of HA-S vs. TOC is due to low fractions of diagenetic OS in the pool. ROS is mainly from riverine inputs and anthropogenic OS has been superimposed on this pool. Spatial coupling among TOC, pyrite-S and FA-S is a sensitive indicator of anthropogenic impacts on benthic processes of the bay.
Показать больше [+] Меньше [-]Particle nucleation in a forested environment Полный текст
2014
Nallathamby, Punith D. | Hopke, Philip K. | Rossner, Alan | Dhaniyala, Suresh | Marzocca, P. (Piergiovanni) | Petaja, Tuukka | Barthelmie, Rebecca J. | Pryor, Sara C.
Atmospheric nucleation is now recognized to be an important source of ambient particles. In this study, ground–based measurements using a tower were used to observe new particle formation in the Morgan Monroe State Forest (MMSF) in Southwestern Indiana in May 2008. Nucleation was observed at MMSF on a number of days through examination of the particle size distributions. Most of these events were nucleation and growth events that are typical of regional nucleation phenomena. The particle size and sulfuric acid concentration data were used to investigate the mechanism for the observed nucleation events. Four of the ten observed nucleation events were clearly the result of activation of pre–existing clusters. The others seem likely to be the result of classical ternary nucleation.
Показать больше [+] Меньше [-]Physicochemical characteristics of PM2.5: Low, middle, and high–income group homes in Agra, India–a case study Полный текст
2014
Singh, Pradyumn | Saini, Renuka | Taneja, Ajay
The present study shows the current scenario of the aggregate relation between income and pollution at the household level. The indoor sampling of fine particulate matter was conducted in low– middle– and high–income group homes in Agra City, the North Central region of India. The mean indoor concentrations of PM2.5 were 46.7μg/m3, 39.2μg/m3 and 25.6μg/m3 in low– middle– and high–income group homes respectively. The full–day variation revealed that the concentrations of fine particles were higher during morning and evening hours in all the three income group homes. The indoor meteorological parameters were also monitored. Using scanning electron microscopy coupled with energy dispersive x–ray spectrometer (SEM–EDS) chemical and elemental analysis of fine particles and their probable sources has been conducted in low– middle– high–income group homes. EDS spectra indicates the elemental composition of PM2.5 which can be distributed into following groups of particles i.e. C–O rich (54%), F rich (42%) and other (4%) in low–income group homes. In middle– and high–income group homes F rich (59–65%), C–O rich (32–37%) and other (3–4%) were observed in PM2.5. The SEM images of fine particles indicates that the particles are clustered into following groups i.e. aluminosilicates/silica particles, spherical carbon rich particles, nearly spherical fluorine rich particles, Mg–Si or Mg–Si–Al particles.
Показать больше [+] Меньше [-]Naphthalene degradation in seawater by UV irradiation: The effects of fluence rate, salinity, temperature and initial concentration Полный текст
2014
Jing, Liang | Chen, Bing | Zhang, Baiyu | Zheng, Jisi | Liu, Bo
A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries.
Показать больше [+] Меньше [-]Oil spill hazard assessment using a reverse trajectory method for the Egadi marine protected area (Central Mediterranean Sea) Полный текст
2014
Ciappa, Achille | Costabile, Salvatore
The Egadi Marine Protected Area (MPA) on the western side of the Sicily Channel (Central Mediterranean) is exposed to a high risk of oil pollution from the tanker routes connecting the eastern and western basins of the Mediterranean Sea. Areas where an oil spill would do most damage, and thus where surveillance should be concentrated, are identified in this study by Lagrangian tracers tracked backwards in time from points along the MPA perimeter using data spanning six years from 2006 to 2011. Results indicate that the areas where oil surveillance would be most beneficial are segments of the tanker routes south of Sicily (highly frequented) and north of Sicily (scarcely frequented), both extending about 150 miles from November to March and 100 miles in the other months. The third route, close to the Tunisian shore, is the most frequented by oil tankers but the threat period is limited to November and December.
Показать больше [+] Меньше [-]Enhancing the management response to oil spills in the Tuscany Archipelago through operational modelling Полный текст
2014
Janeiro, João | Zacharioudaki, Anna | Sarhadi, Ehsan | Neves, Augusto | Martins, Flavio
A new approach towards the management of oil pollution accidents in marine sensitive areas is presented in this work. A set of nested models in a downscaling philosophy was implemented, externally forced by existing regional operational products. The 3D hydrodynamics, turbulence and the oil transport/weathering models are all linked in the same system, sharing the same code, exchanging information in real time and improving its ability to correctly reproduce the spill. A wind-generated wave model is also implemented using the same downscaling philosophy. Observations from several sources validated the numerical components of the system. The results obtained highlight the good performance of the system and its ability to be applied for oil spill forecasts in the region. The success of the methodology described in this paper was underline during the Costa Concordia accident, where a high resolution domain was rapidly created and deployed inside the system covering the accident site.
Показать больше [+] Меньше [-]Estimation of the annual flow and stock of marine debris in South Korea for management purposes Полный текст
2014
Jang, Yong Chang | Lee, Jongmyoung | Hong, Sunwook | Mok, Jin Yong | Kim, Kyoung-Shin | Lee, Yun Jeong | Choi, Hyun-Woo | Kang, Hongmook | Lee, Sukhui
The annual flow and stock of marine debris in the Sea of Korea was estimated by summarizing previous survey results and integrating them with other relevant information to underpin the national marine debris management plan. The annual inflow of marine debris was estimated to be 91,195tons [32,825tons (36% of the total) from sources on land and 58,370tons (64%) from ocean sources]. As of the end of 2012, the total stock of marine debris on all South Korean coasts (12,029tons), the seabed (137,761tons), and in the water column (2451tons) was estimated to be 152,241tons. In 2012, 42,595tons of marine debris was collected from coasts, seabeds, and the water column. This is a very rare case study that estimated the amount of marine debris at a national level, the results of which provide essential information for the development of efficient marine debris management policies.
Показать больше [+] Меньше [-]Cryptosporidium and Giardia in tropical recreational marine waters contaminated with domestic sewage: Estimation of bathing-associated disease risks Полный текст
2014
Betancourt, Walter Q. | Duarte, Diana C. | Vásquez, Rosa C. | Gurian, Patrick L.
Sewage is a major contributor to pollution problems involving human pathogens in tropical coastal areas. This study investigated the occurrence of intestinal protozoan parasites (Giardia and Cryptosporidium) in tropical recreational marine waters contaminated with sewage. The potential risks of Cryptosporidium and Giardia infection from recreational water exposure were estimated from the levels of viable (oo) cysts (DIC+, DAPI+, PI−) found in near-shore swimming areas using an exponential dose response model. A Monte Carlo uncertainty analysis was performed in order to determine the probability distribution of risks. Microbial indicators of recreational water quality (enterococci, Clostridium perfringens) and genetic markers of sewage pollution (human-specific Bacteroidales marker [HF183] and Clostridium coccoides) were simultaneously evaluated in order to estimate the extent of water quality deterioration associated with human wastes. The study revealed the potential risk of parasite infections via primary contact with tropical marine waters contaminated with sewage; higher risk estimates for Giardia than for Cryptosporidium were found. Mean risks estimated by Monte Carlo were below the U.S. EPA upper bound on recreational risk of 0.036 for cryptosporidiosis and giardiasis for both children and adults. However, 95th percentile estimates for giardiasis for children exceeded the 0.036 level. Environmental surveillance of microbial pathogens is crucial in order to control and eradicate the effects that increasing anthropogenic impacts have on marine ecosystems and human health.
Показать больше [+] Меньше [-]Water solubility of metals in coarse PM and PM2.5 in typical urban environment in Hong Kong Полный текст
2014
Jiang, Sabrina Y.N. | Yang, Fenhuan | Chan, Ka Lok | Ning, Zhi
An investigation of abundance and solubility of metals in size–segregated particulate matter (PM) was conducted at a typical urban site during the winter between late 2011 and early 2012 in Kowloon Tong, Hong Kong. The samples were extracted by both strong acid and water, and fourteen elements including Al, Ca, Cd, Cr, Co, Cu, Fe, Pb, Mg, Mn, Mo, Ni, V, and Zn were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP–OES) and Inductively Coupled Plasma Mass Spectrometry (ICP–MS). The metals in PM showed distinctly different profiles of their distribution between coarse particles (2.5μm<dp<10μm) and PM2.5 (dp<2.5μm). The upper continental crustal enrichment factors (CEFs) of the measured metals for two particle size fractions showed that CEFs for nine of fourteen metals in PM2.5 were higher than 10 while Cd, Pb, Zn, Mn and Cu were far above 100; whereas for coarse particles, the CEFs of most elements were lower than 10, except for Cd being higher than 100. Water and acid extractable fractions of coarse PM and PM2.5 were analyzed and compared to investigate the transition metals solubility. The water extractable fraction was found to be present mainly in the fine particles, whereas more of the coarse fraction mass remained as insoluble fraction. The results from this study demonstrated large variation of water solubility of metals in urban aerosols in different size fractions and highlighted solubility as an important metric for considering the relation between metals and adverse health effects in epidemiological and toxicological studies.
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