خيارات البحث
النتائج 751 - 760 من 2,500
Effects of sewage discharges on lipid and fatty acid composition of the Patagonian bivalve Diplodon chilensis
2014
Rocchetta, Iara | Pasquevich, María Y. | Heras, Horacio | Ríos de Molina, María del Carmen | Luquet, Carlos M.
Lipid and fatty acid (FA) composition and selected oxidative stress parameters of freshwater clams (Dipolodon chilensis), from a sewage-polluted (SMA) and a clean site, were compared. Trophic markers FA were analyzed in clams and sediment. Saturated FA (SAFA), and bacteria and sewage markers were abundant in SMA sediments, while diatom markers were 50% lower. Proportions of SAFA, branched FA, 20:5n−3 (EPA) and 22:6n−3 (DHA) were higher in SMA clams. Chronic exposure of D. chilensis to increasing eutrophication affected its lipid and FA composition. The increase in EPA and DHA proportions could be an adaptive response, which increases stress resistance but could also lead to higher susceptibility to lipid peroxidation TBARS, lipofuscins (20-fold) and GSH concentrations were higher in SMA clams. FA markers indicated terrestrial plant detritus and bacteria are important items in D. chilensis diet. Anthropogenic input in their food could be traced using specific FA as trophic markers.
اظهر المزيد [+] اقل [-]Historical records of organic pollutants in sediment cores
2014
Bigus, Paulina | Tobiszewski, Marek | Namieśnik, Jacek
Analyses of sediment core samples are primary sources of historical pollution trends in aquatic systems. Determining organic compounds, such as POPs, in the dated sediments enables the estimation of their temporal concentration changes and the identification of the contaminant origin in local regions. Wars, large-scale fires, economical transitions, and bans on certain chemicals are reflected in the sediment organic compound concentrations. The high POP concentrations in surficial sediments suggest that these chemicals, even after being banned, remain in the environment. Furthermore, vertical profiles can help in understanding the sedimentation process and in estimating effective countermeasures against pollution. Moreover, studies published during the period 1991–2013 on PAHs, PCBs, OCPs, dioxins and dioxin-like compound concentrations in sediment core samples are reviewed.
اظهر المزيد [+] اقل [-]Growth, nutrient status, and photosynthetic response to diesel-contaminated soil of a cordgrass, Spartina argentinensis
2014
Redondo-Gómez, Susana | Petenello, María C. | Feldman, Susana R.
The present study was conduced to investigate the tolerance limits of Spartina argentinensis, which occurs in inland marshes of the Chaco-Pampean regions of Argentina, to diesel-contaminated soil. A glasshouse experiment was designed to investigate the effect of diesel fuel from 0% to 3% on growth and photosynthetic apparatus of S. densiflora by measuring gas exchange and photosynthetic pigments. We also performed chemical analysis of plant samples, and determined mycorrhizal index. Tiller and root biomasses declined with increasing diesel fuel concentration, as well as photosynthetic rate (A). Reductions in A could be accounted for by non-stomatal limitations. Mycorrhizal roots of S. argentinensis were reduced by the presence of diesel fuel, but did not affect its nutritional status; in fact, most element concentrations increased with diesel contamination. Despite the negative effect of diesel-contaminated soil, S. argentinensis continued growing, which could be useful management options for phytorremediation of diesel-contaminated soils.
اظهر المزيد [+] اقل [-]Coral reef baselines: How much macroalgae is natural?
2014
Bruno, John F. | Precht, William F. | Vroom, Peter S. | Aronson, Richard B.
Identifying the baseline or natural state of an ecosystem is a critical step in effective conservation and restoration. Like most marine ecosystems, coral reefs are being degraded by human activities: corals and fish have declined in abundance and seaweeds, or macroalgae, have become more prevalent. The challenge for resource managers is to reverse these trends, but by how much? Based on surveys of Caribbean reefs in the 1970s, some reef scientists believe that the average cover of seaweed was very low in the natural state: perhaps less than 3%. On the other hand, evidence from remote Pacific reefs, ecological theory, and impacts of over-harvesting in other systems all suggest that, historically, macroalgal biomass may have been higher than assumed. Uncertainties about the natural state of coral reefs illustrate the difficulty of determining the baseline condition of even well studied systems.
اظهر المزيد [+] اقل [-]PM10 black carbon and ionic species concentration of urban atmosphere in Makassar of South Sulawesi Province, Indonesia
2014
Rashid, Mohd | Yunus, Sattar | Mat, Ramli | Baharun, Sabariah | Lestari, Puji
This paper presents a study on black carbon and ionic species concentrations in PM10, sampled from the urban area of Makassar in the Province of South Sulawesi, Indonesia. The samples were collected on a weekly basis within a period of one year from February 2012 to January 2013. Results showed that the mean concentration of PM10 black carbon was 2.01±0.93μg/m3, while ionic species concentrations were found in descending order; SO42−>NO3−>Cl−>NH4+, with mean concentrations of 1.44±1.04μg/m3, 1.11±1.06μg/m3, 0.87±0.91μg/m3, 0.49±0.64μg/m3, respectively. Black carbon concentration was higher during the dry months, which may be attributed to uncontrolled biomass burning during hot and dry weather conditions. Similarly, SO42− and NH4+ concentrations were higher during the dry month seasons. On the contrary, Cl− concentration was higher during the wet months, influenced by the marine environment surrounding the area.
اظهر المزيد [+] اقل [-]Evaluation of airborne Actinomycetes at waste application facilities
2014
Awad, Abdel Hameed | El Gendy, Safa A.
This study aimed to evaluate airborne meso–and–thermophilic actinomycete concentrations and their types at a wastewater treatment plant and a biosolid landfill, in Egypt. Air samples were collected at 200m upwind, and onsite and 300m downwind by using liquid impinger sampler, calibrated to draw 12.5L/min, for 20 minutes. The concentrations ranged between 0.0–7 360CFU/m3 for mesophilic, and 106–586CFU/m3 for thermophilic actinomycetes. Airborne actinomycete concentrations exceeded the suggested occupational exposure limit value of 100CFU/m3. No significant correlations were found between actinomycete concentrations onsite and 300m downwind distance. At the biosolid landfill, upwind thermophilic actinomycetes significantly differed (p<0.05) from onsite and 300m downwind. A total of 40 and 69 airborne actinomycete isolates belonging to 8 genera were identified at the wastewater treatment plant and biosolid landfill. Streptomyces were the dominant actinomycete species. Streptomyces diastaticus, Pseudonocardia compacta and Catellatospora ferruginea were only detected at the biosolid landfill site. Meso–and–thermophilic actinomycetes positively associated with relative humidity, and wind speed positively correlated with onsite thermophilic actinomycetes (r=0.65) at the biosolid landfill. Temperature showed negative effect on survivability of mesophilic actinomycetes (r=-0.8) onsite of the wastewater treatment plant. Waste application facilities increase actinomycete concentrations onsite which may consequently deteriorate air quality in the nearby areas.
اظهر المزيد [+] اقل [-]Leaf injury and gas exchange in Ipomoea nil cv. Scarlett O’Hara, an ozone bioindicator species, in Sao Paulo, Brazil
2014
Moraes, Regina M. | Meirelles, Sergio T. | Silva, Simone F. | Silva, Daiane T. | de Assis, Pedro I.L.S. | Viola, Sandra R.A.S.
Ipomoea nil (L.) Roth. cv. ‘Scarlett O’Hara’ was evaluated as a tropical bioindicator species sensitive to ozone (O3). A total of nine field experiments were performed, with 28 days of exposure each. Visible leaf injuries, carbon assimilation (Asat) and stomatal conductance (gs) were quantified and correlated to oscillations in environmental conditions and accumulated ozone exposure over a threshold of 40 ppb h (AOT40). The values of gas exchange and leaf injury continuously varied throughout the study period. Asat and leaf injury (chlorosis) were higher in spring than in others seasons. The gs was higher in autumn. The analyses of the abiotic and biotic variables revealed an opposing trend between the Asat and both leaf injury and AOT40. Ozone levels were moderate and its relationship with gs was inverse. This may be the cause of the moderate injury. ‘Scarlett O’Hara’ is sensitive to O3 and has potential as an O3 bioindicator in sub–tropical regions.
اظهر المزيد [+] اقل [-]Multivariate statistical approach to identify significant sources influencing the physico-chemical variables in Aerial Bay, North Andaman, India
2014
Jha, Dilip Kumar | Vinithkumar, N.V. | Sahu, Biraja Kumar | Das, Apurba Kumar | Dheenan, P.S. | Venkateshwaran, P. | Begum, Mehmuna | Ganesh, T. | Prashanthi Devi, M. | Kirubagaran, R.
Aerial Bay is one of the harbor towns of Andaman and Nicobar Islands, the union territory of India. Nevertheless, it is least studied marine environment, particularly for physico-chemical assessment. Therefore, to evaluate the annual spatiotemporal variations of physico-chemical parameters, seawater samples collected from 20 sampling stations covering three seasons were analyzed. Multivariate statistics is applied to the investigated data in an attempt to understand the causes of variation in physico-chemical parameters. Cluster analysis distinguished mangrove and open sea stations from other areas by considering distinctive physico-chemical characteristics. Factor analysis revealed 79.5% of total variance in physico-chemical parameters. Strong loading included transparency, TSS, DO, BOD, salinity, nitrate, nitrite, inorganic phosphate, total phosphorus and silicate. In addition, box-whisker plots and Geographical Information System based land use data further facilitated and supported multivariate results.
اظهر المزيد [+] اقل [-]Isolation and characterization of a novel hydrocarbon-degrading bacterium Achromobacter sp. HZ01 from the crude oil-contaminated seawater at the Daya Bay, southern China
2014
Deng, Mao-Cheng | Li, Jing | Liang, Fu-Rui | Yi, Meisheng | Xu, Xiao-Ming | Yuan, Jian-Ping | Peng, Juan | Wu, Chou-Fei | Wang, Jiang-Hai
Microorganisms play an important role in the biodegradation of petroleum contaminants, which have attracted great concern due to their persistent toxicity and difficult biodegradation. In this paper, a novel hydrocarbon-degrading bacterium HZ01 was isolated from the crude oil-contaminated seawater at the Daya Bay, South China Sea, and identified as Achromobacter sp. Under the conditions of pH 7.0, NaCl 3% (w/v), temperature 28°C and rotary speed 150rpm, its degradability of the total n-alkanes reached up to 96.6% after 10days of incubation for the evaporated diesel oil. Furthermore, Achromobacter sp. HZ01 could effectively utilize polycyclic aromatic hydrocarbons (PAHs) as its sole carbon source, and could remove anthracene, phenanthrene and pyrence about 29.8%, 50.6% and 38.4% respectively after 30days of incubation. Therefore, Achromobacter sp. HZ01 may employed as an excellent degrader to develop one cost-effective and eco-friendly method for the bioremediation of marine environments polluted by crude oil.
اظهر المزيد [+] اقل [-]Young green turtles, Chelonia mydas, exposed to plastic in a frontal area of the SW Atlantic
2014
González Carman, Victoria | Acha, E Marcelo | Maxwell, Sara M. | Albareda, Diego | Campagna, Claudio | Mianzan, Hermes
Ingestion of anthropogenic debris represents an important threat to marine turtle populations. Information has been limited to inventories of debris ingested and its consequences, but why ingestion occurs and the conditions that enable it are less understood. Here we report on the occurrence of plastic ingestion in young green turtles (Chelonia mydas) inhabiting the Río de la Plata (SW Atlantic). This estuarine area is characterized by a frontal system that accumulates anthropogenic debris. We explored exposure of green turtles to plastic and its ingestion via debris distribution, habitat use and digestive tract examination. Results indicated that there is considerable overlap of frontal accumulated plastic and core foraging areas of the animals. Exposure results in ingestion, as shown by the high frequency of plastic found in the digestive tracts. The Río de la Plata estuarine front is an area of conservation concern for young green turtles.
اظهر المزيد [+] اقل [-]