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Polycyclic aromatic hydrocarbons (PAHs) in the mariculture zones of China’s northern Yellow Sea Texte intégral
2014
Zong, Humin | Ma, Xindong | Na, Guangshui | Huo, Chuanlin | Yuan, Xiutang | Zhang, Zhifeng
Polycyclic aromatic hydrocarbons (PAHs) were detected in water and sediment samples collected from three mariculture zones in China’s northern Yellow Sea. In these samples, total PAH concentrations ranged from 110.8ng/L to 997.2ng/L and 142.2ng/gdry weight (dw) to 750.2ng/gdw, respectively. The log KOC values of the various PAH compounds examined in this study increased with the log KOW values, which is consistent with the prediction regarding PAH behavior in the environment. However, these KOC values were lower than the predicted values as a result of the effects of organic matters, which were abundant in the mariculture water. The isomeric ratios of the PAHs in sediment indicated that the source of the PAHs in the mariculture zones were mainly pyrolytic. The TEQcarc values of PAHs ranged from 7ng TEQ/gdw to 92ng TEQ/gdw, and only a few samples met the safe criterion with respect to individual PAH concentrations.
Afficher plus [+] Moins [-]Status of trace metals in surface seawater of the Gulf of Aqaba, Saudi Arabia Texte intégral
2014
Al-Taani, Ahmed A. | Batayneh, Awni | Nazzal, Yousef | Ghrefat, Habes | Elawadi, Eslam | Zaman, Haider
The Gulf of Aqaba (GoA) is of significant ecological value with unique ecosystems that host one of the most diverse coral communities in the world. However, these marine environments and biodiversity have been threatened by growing human activities. We investigated the levels and distributions of trace metals in surface seawater across the eastern coast of the Saudi GoA. Zn, Cu, Fe, B and Se in addition to total dissolved solids and seawater temperature exhibited decreasing trends northwards. While Mn, Cd, As and Pb showed higher average levels in the northern GoA. Metal input in waters is dependent on the adjacent geologic materials. The spatial variability of metals in water is also related to wave action, prevailing wind direction, and atmospheric dry deposition from adjacent arid lands. Also, water discharged from thermal desalination plants, mineral dust from fertilizer and cement factories are potential contributors of metals to seawater water, particularly, in the northern GoA.
Afficher plus [+] Moins [-]Assessment of trace elements and legacy contaminant concentrations in California Mussels (Mytilus spp.): Relationship to land use and outfalls Texte intégral
2014
Edwards, M. | Jacob, A.P. | Kimbrough, K.L. | Davenport, E. | Johnson, W.E.
NOAA’s Mussel Watch Program funded a regional pilot project in California that characterized contaminants associated with various land uses in conjunction with state, federal and private partners. Herein we assess the magnitude and distribution of trace elements and persistent organic contaminants in indigenous mussels with respect to land use, presence of outfalls and a subset of California Areas of Special Biological Significance (ASBS). We detected significant differences among the land use categories for the majority of trace elements and legacy contaminants measured. There was no significant difference between sites with and without outfalls. PCBs and PAHs were significantly lower in sites within ASBS boundary compared to other sites. The findings of this study will help fine tune future regional and national assessments as well as guide development of resource management and remediation activities and programs.
Afficher plus [+] Moins [-]Meteorologically-driven circulation and flushing times of the Bay of Algeciras, Strait of Gibraltar Texte intégral
2014
Sánchez-Garrido, José C. | Lafuente, Jesús García | Sammartino, Simone | Naranjo, Cristina | de los Santos, Francisco J. | Álvarez Fanjul, Enrique
A primitive-equation model has been used to investigate the meteorologically-driven circulation of the Bay of Algeciras. It is shown that the mean circulation of Atlantic Water (AW) is characterized by an anticyclonic cell, while Mediterranean Water (MW) follows a preferred cyclonic pathway. Meteorological forcing distorts substantially the AW mean circulation pattern, and only modulates that of the MW. Winds drive a vertical circulation cell in the Atlantic layer consistent with Ekman dynamics, whereas the horizontal circulation pattern is markedly dependent on the swift Atlantic jet entering the Mediterranean and changes from clearly anticyclonic to cyclonic as the jet separates or approaches the strait’s northern shoreline. This occurs through atmospheric pressure-driven acceleration/deceleration of the jet, in agreement with internal hydraulics theory predictions. It is also found that the renewal of AW is largely modulated by tides, with meteorological forcing playing a secondary role. The opposite applies to the renewal of MW.
Afficher plus [+] Moins [-]Transport of the Saharan dust air plumes over the tropical North Atlantic from FORMOSAT–3/COSMIC observation Texte intégral
2014
Wang, Kuo–Ying | Liu, Chao–Han
Long–range transport of the Saharan dust plumes during May–August of each year is a prominent feature over the tropical North Atlantic. Observations of temperature profiles are highly desirable in clarifying the impacts of the Saharan dust plumes over the tropical North Atlantic. In this work we evaluate positive temperature anomalies (inversions in the lower troposphere) in the North Atlantic low troposphere originating from Western Africa, and to examine the correspondence of these events to Saharan dust plumes, using several temperature sources and satellite–detected measurements of Aerosol Index. We combine profiles of temperature observations from FORMOSAT–3/COSMIC (F3C) with aerosol observations from Ozone Monitoring Instrument (OMI) to provide direct evidence of the Saharan dust plumes modifying environmental stability. The F3C observations show good profile measurements compared with the radiosondes in the lower troposphere, with the average temperature differences less than 0.5K. The F3C results were also compared with the Aqua Advanced Infrared Radiation Sounder (AIRS) and meteorological analyses from the National Centers for Environmental Predictions (NCEP), the United Kingdom Met Office (UKMO), and the European Centre for Medium Range Weather Forecast (ECMWF). Our results show that hot air plumes are associated with the Saharan dust plumes during their transport across the tropical North Atlantic. There were eleven distinctive hot air plumes during May–August 2007 and 2008, respectively. These hot air plumes increase environmental temperatures below 5–km altitudes, with the maximum increase of 1–2K around 2–km. This leads to increase of environmental stability below 2–km altitudes and decrease of environmental stability between 2– and 5–km altitudes. By changing the vertical distribution of environmental stability, the Saharan dust plumes act to stabilize environmental air below 2–km while destabilize environmental air from 2– to 5–km altitudes. These results are distinctively presented in the F3C and AIRS observations but less obvious in the meteorological analyses.
Afficher plus [+] Moins [-]An alert system for triggering different levels of coastal management urgency: Tunisia case study using rapid environmental assessment data Texte intégral
2014
Price, A.R.G. | Jaoui, K. | Pearson, M.P. | Jeudy de Grissac, A.
Rapid environmental assessment (REA) involves scoring abundances of ecosystems/species groups and magnitude of pressures, concurrently, using the same logarithmic (0–6) assessment scale. We demonstrate the utility of REA data for an alert system identifying different levels of coastal management concern. Thresholds set for abundances/magnitudes, when crossed, trigger proposed responses. Kerkennah, Tunisia, our case study, has significant natural assets (e.g. exceptional seagrass and invertebrate abundances), subjected to varying levels of disturbance and management concern. Using REA thresholds set, fishing, green algae/eutrophication and oil occurred at ‘low’ levels (scores 0–1): management not (currently) necessary. Construction and wood litter prevailed at ‘moderate’ levels (scores 2–4): management alerted for (further) monitoring. Solid waste densities were ‘high’ (scores 5–6): management alerted for action; quantities of rubbish were substantial (20–200itemsm−1 beach) but not unprecedented. REA is considered a robust methodology and complementary to other rapid assessment techniques, environmental frameworks and indicators of ecosystem condition.
Afficher plus [+] Moins [-]Characterization of atmospheric mercury at a suburban site of central China from wintertime to springtime Texte intégral
2014
Hu, Qi–Hou | Kang, Hui | Li, Zheng | Wang, Yu–Suo | Ye, Pei–Pei | Zhang, Lu–Lu | Yu, Juan | Yu, Xia–Wei | Sun, Chen | Xie, Zhou–Qing
Atmospheric mercury exits primarily as gaseous mercury and particulate mercury (PHg). Change in the species of atmospheric mercury will pose significant impact on the biogeochemical process of mercury. Here total gaseous mercury (TGM) and total particulate mercury (TPM) were measured from heating season in wintertime to springtime with frequent dust storm during February to May 2009 in the suburban of Hefei, central China, where atmospheric mercury measurements were completely absent. The average concentrations of TGM and TPM were 2.57±1.37ng/m3 and 0.32±0.10ng/m3, respectively. Variations in the TGM were affected by both emissions and meteorological parameters. In the heating period (February), due to coal combustion TGM concentrations were significantly higher than those in the spring (March, April and May). A clear different diurnal variation in TGM concentration was also observed both in late winter and in spring, accompanying with the advance of sunrise. The percentage of total particulate mercury (TPM) in total atmospheric Hg ranged from 5.8%–19.2%, with relatively high levels appeared in March and April. PHg was mainly derived from direct emissions by coal combustion in February and May, while it was dominated by transformation from gaseous Hg on particles in March and April due to dust storms, which may result in more deposition of mercury to ecosystem.
Afficher plus [+] Moins [-]Conservation management options and actions: Putative decline of coral cover at Palmyra Atoll, Northern Line Islands, as a case study Texte intégral
2014
Gardner, Jonathan P.A. | John Bartz, R. | Brainard, Russell E. | Collen, John D. | Dunbar, Robert B. | Garton, David W. | Powell, Sam
Localised loss of live coral cover at Palmyra Atoll (central Pacific Ocean) has been attributed to increased temperature and/or sedimentation arising from alterations made to the lagoon system. It has been hypothesised that a causeway spanning the lagoon hinders water circulation, resulting in warmer and/or more turbid water flowing towards a site of high coral cover and diversity (Coral Gardens). Analyses of a multi-site and multi-year data set revealed no differences in mean temperature or turbidity values on either side of the causeway and provided no evidence of significantly warmer or more turbid water at Coral Gardens. We conclude that the putative decline in live coral cover cannot be attributed to the presence of the causeway and that proposed management actions involving modification to the causeway cannot achieve the conservation outcomes suggested of them.
Afficher plus [+] Moins [-]Physicochemical characteristics of PM2.5: Low, middle, and high–income group homes in Agra, India–a case study Texte intégral
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.
Afficher plus [+] Moins [-]A study of anthropogenic and climatic disturbance of the New River Estuary using a Bayesian belief network Texte intégral
2014
Nojavan A., Farnaz | Qian, Song S. | Paerl, Hans W. | Reckhow, Kenneth H. | Albright, Elizabeth A.
The present paper utilizes a Bayesian Belief Network (BBN) approach to intuitively present and quantify our current understanding of the complex physical, chemical, and biological processes that lead to eutrophication in an estuarine ecosystem (New River Estuary, North Carolina, USA). The model is further used to explore the effects of plausible future climatic and nutrient pollution management scenarios on water quality indicators. The BBN, through visualizing the structure of the network, facilitates knowledge communication with managers/stakeholders who might not be experts in the underlying scientific disciplines. Moreover, the developed structure of the BBN is transferable to other comparable estuaries. The BBN nodes are discretized exploring a new approach called moment matching method. The conditional probability tables of the variables are driven by a large dataset (four years). Our results show interaction among various predictors and their impact on water quality indicators. The synergistic effects caution future management actions.
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