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Результаты 651-660 из 2,492
Estuarine macrofauna responses to continuous in situ nutrient addition on a tropical mudflat
2014
Botter-Carvalho, Mônica L. | Carvalho, Paulo V.V.C. | Valença, Ana Paula M.C. | Santos, Paulo J.P.
A field experiment to assess the effects of continuous nutrient addition on the macrobenthic community was carried out on an estuarine mudflat on the northeast coast of Brazil. The experiment began on 5 October 2005 and ended on 8 February 2006. Macrofauna was compared at approximately four-week intervals in triplicate plots with three levels (Control – C, Low Dose – LD and High Dose – HD) of weekly fertilizer additions for 17weeks. Inorganic fertilizer (N–P–K) was applied on nine randomly defined quadrangular plots (4m2 each). All measurements were calculated from species abundances. Multivariate analyses as well as the univariate indices (richness, abundance and Shannon–Wiener index) showed statistically significant differences between the enriched and control areas during the period of the experiment. The expected gradual response based on the succession model of Pearson and Rosenberg was not observed. The nutrient doses used were high enough to cause severe decreases in abundance, richness and evenness, and an increase in dominance.
Показать больше [+] Меньше [-]Source speciation resolving hydrochemical complexity of coastal aquifers
2014
Sonkamble, Sahebrao | Chandra, Subash | Ahmed, Shakeel | Rangarajan, R.
There is a growing concern of seawater intrusion to freshwater aquifers due to groundwater overexploitation in the eastern coastal belt of Southern India. The problem becomes complex in the regions where industrial effluents are also contaminating the freshwater aquifers. In order to understand the hydrochemical complexity of the system, topographic elevation, static water level measurements, major ion chemistry, ionic cross plots, water type contours and factor analysis were applied for 144 groundwater samples of shallow and deep sources from Quaternary and Tertiary coastal aquifers, located within the industrial zone of 25 km2 area near Cuddalore, Southern India. The ionic cross plots indicates dissolution of halite minerals from marine sources and seawater mixing into inland aquifers up to the level of 9.3%. The factor analysis explains three significant factors totaling 86.3% of cumulative sample variance which includes varying contribution from marine, industrial effluent and freshwater sources.
Показать больше [+] Меньше [-]Marine litter in Mediterranean sandy littorals: Spatial distribution patterns along central Italy coastal dunes
2014
Poeta, Gianluca | Battisti, Corrado | Acosta, Alicia T.R.
Sandy shores are generally considered important sinks for marine litter and the presence of this litter may represent a serious threat to biotic communities and dune integrity mostly due to cleaning activities carried out through mechanical equipment. In spring (April–May) 2012 we sampled 153 2×2m random plots to assess the spatial distribution patterns of litter on Central Italy sandy shores. We analysed the relationship between the presence of litter and coastal dune habitats along the sea-inland gradient. Our results showed that the most frequent litter items were plastic and polystyrene. Differences of marine litter spatial distribution were found between upper beach and fore dune habitats and fixed dune habitats: embryo dune and mobile dune habitats show the highest frequency of litter, but, surprisingly, marine litter did not impact fixed dune habitats, these possibly acting as a natural barrier protecting the inner part of the coast from marine litter dispersion.
Показать больше [+] Меньше [-]Time–series analysis of surface ozone and nitrogen oxides concentrations in an urban area at Brazil
2014
Agudelo–Castaneda, Dayana Milena | Teixeira, Elba Calesso | Norte Pereira, Felipe
The purpose of the present work was to study the concentration variations in O3, NO, NO2, NOX over a 4–year period (2006–2009), using the Kolmogorov–Zurbenko filter. Data were decomposed into seasonal and trend components. Seasonal component of the time–series analysis (2006–2009) of NO and NOx in Canoas and Esteio showed values above average during the cold seasons, while O3 showed an opposite pattern. The trend component was marked by the decrease of NO2 at Canoas and the increase of NO at Esteio, thus revealing their variation (NO and NOX) due to local emissions. Furthermore, evaluations of the mean daily concentrations of NO, NOX, NO2, O3, PM10 and CO, and correlations of these pollutants with meteorological parameters (ambient temperature, wind velocity, solar radiation and relative humidity) allowed the confirmation of the influence of mobile sources in the study area.
Показать больше [+] Меньше [-]Characterization of fish hold effluent discharged from commercial fishing vessels into harbor waters
2014
Albert, Ryan J. | McLaughlin, Christine | Falatko, Debra
Fish hold effluent and the effluent produced from the cleaning of fish holds may contain organic material resulting from the degradation of seafood and cleaning products (e.g., soaps and detergents). This effluent is often discharged by vessels into near shore waters and, therefore, could have the potential to contribute to water pollution in bays and estuaries. We characterized effluent from commercial fishing vessels with holds containing refrigerated seawater, ice slurry, or chipped ice. Concentrations of trace heavy metals, wet chemistry parameters, and nutrients in effluent were compared to screening benchmarks to determine if there is a reasonable potential for effluent discharge to contribute to nonattainment of water quality standards. Most analytes (67%) exceeded their benchmark concentration and, therefore, may have the potential to pose risk to human health or the environment if discharges are in significant quantities or there are many vessels discharging in the same areas.
Показать больше [+] Меньше [-]Deepwater marine litter densities and composition from submersible video-transects around the ABC-islands, Dutch Caribbean
2014
Debrot, A.O. | Vinke, E. | van der Wende, G. | Hylkema, A. | Reed, J.K.
Baseline data on anthropogenic seafloor debris contamination in the year 2000 is provided for 24 submersible video transects at depths of 80–900m, off the Dutch ABC-islands (Aruba, Bonaire, Curaçao), in the southeastern Caribbean Sea. In total, 202 objects were documented from a combined 21,184m of transect, ranging from sandy lower island-slope to rocky upper island-slope habitat. Debris densities differed significantly with depth. Highest debris accumulation (0.459 items 100m−2 or 4590 items per km2) occurred at depths of 300–600m on more shallow-sloping (20–30°) sand and silt bottoms. The overall average debris density was 0.27 objects per 100m2 (or 2700 items per km2), which is an order of magnitude higher than most other deepwater debris studies. What we describe may be representative for other small, populated, steep volcanic Caribbean islands. Food and beverage-related items were the single largest usage category identified (44% of objects; mostly glass beverage bottles).
Показать больше [+] Меньше [-]Enzymatic methods for the determination of pollution in seawater using salt resistant alkaline phosphatase from eggs of the sea urchin Strongylocentrotus intermedius
2014
Menzorova, Natalie I. | Seitkalieva, Alexandra V. | Rasskazov, Valerу A.
A new salt resistant alkaline phosphatase from eggs of the sea urchin Strongylocentrotus intermedius (StAP) has been shown to have a unique property to hydrolyze substrate in seawater without loss of enzymatic activity. The enzyme has pH optimum at 8.0–8.5. Model experiments showed various concentrations of copper, zinc, cadmium and lead added to seawater or a standard buffer mixture to inhibit completely the enzyme activity at the concentrations of 15–150μg/l. StAP sensitivity to the presence in seawater of metals, pesticides, detergents and oil products appears to be considerably less. Samples of seawater taken from aquatic areas of the Troitsy Bay of the Peter the Great Bay, Japan Sea have been shown to inhibit the enzyme activity; the same was shown for the samples of fresh waters. The phosphatase inhibition assay developed proved to be highly sensitive, technically easy-to use allowing to test a great number of samples.
Показать больше [+] Меньше [-]Evaluation of concentrations and source contribution of PM10 and SO2 emitted from industrial complexes in Ulsan, Korea: Interfacing of the WRF–CALPUFF modeling tools
2014
Lee, Hyung–Don | Yoo, Jung–Woo | Kang, Min–Kyoung | Kang, Ji–Soon | Jung, Jong–Hyun | Oh, Kwang–Joong
The Ulsan metropolitan city in Korea includes two national industrial complexes [Ulsan Petrochemical Industrial Complex (UPIC) and On–San Industrial Complex (OSIC)] that produce various industrial products. Air pollution from these industrial complexes may pose potential health risks to nearby residential areas. Therefore, WRF–CALPUFF (Weather Research and Forecasting–California PUFF) modeling systems were used to simulate concentration distributions of typical air pollutants (PM10 and SO2), and statistics are computed to determine the models' ability to simulate observations. Finally, we classified the type of business and districts in the region and evaluated their contribution to air pollutant concentrations. Five statistical metrics [Index of Agreement (IOA), Fractional Bias (FB), Normalized Mean Square Error (NMSE), and Pearson correlation coefficient (R)] indicated that the simulated values using CALMET was determined to have sufficient reliability to predict CALPUFF, and simulated concentration field using CALPUFF showed a good agreement [typical values: IOA (0.284 to 0.850 for PM10, 0.412 to 0.895 for SO2), and FB (0.043 to 0.821 for PM10, –0.393 to 0.638 for SO2)] with the observed concentrations. The maximum concentrations of PM10 and SO2 using CALPUFF were predicted to be located around OSIC and UPIC, respectively. We compared the simulated values with observed values at 14 monitoring stations, and the SO2 tended to display better agreement to observed SO2 values than modeled and observed PM10. The source contribution analysis found that PM10 and SO2 were mostly influenced by group B (35.1%) including steel, machinery, and electronic industry nearby OSIC and group A (40.6%) including chemical industry nearby UPIC, respectively. Finally, the correlations between simulated concentrations of PM10 and SO2 and corresponding emission quantities were 0.663 and 0.528, respectively. Overall, the results of this study could be useful for designing appropriate seasonal regulations to reduce ambient concentrations of air pollutants and assisting environmental administrators to control the sources that contribute the most to degradation of air quality.
Показать больше [+] Меньше [-]Source identification of heavy metal contamination using metal association and Pb isotopes in Ulsan Bay sediments, East Sea, Korea
2014
Chae, Jung Sun | Choi, Man Sik | Song, Yun Ho | Um, In Kwon | Kim, Jae Gon
To determine the characteristics of metal pollution sources in Ulsan Bay, East Sea, 39 surface and nine core sediments were collected within the bay and offshore area, and analyzed for metals and stable lead (Pb) isotopes.Most surface sediments (>95% from 48 sites) had high copper (Cu), zinc (Zn), cadmium (Cd), and Pb concentrations that were as much as 1.3 times higher than background values. The primary source of metal contamination came from activities related to nonferrous metal refineries near Onsan Harbor, and the next largest source was from shipbuilding companies located at the mouth of the Taehwa River. Three different anthropogenic sources and background sediments could be identified as end-members using Pb isotopes. Isotopic ratios for the anthropogenic Pb revealed that the sources were imported ores from Australia, Peru, and the United States. In addition, Pb isotopes of anthropogenic Pb discharged from Ulsan Bay toward offshore could be determined.
Показать больше [+] Меньше [-]Concentration, composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar, Arabian Gulf
2014
Soliman, Y.S. | Al Ansari, E.M.S. | Wade, T.L.
Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6ngg−1 to 1025ngg−1. The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe+Ant), (Flt/Flt+Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin.
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