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Resultados 1081-1090 de 4,302
Spatial and seasonal trends of polychlorinated dioxins, furans and dioxin-like polychlorinated biphenyls in air using passive and active samplers and inhalation risk assessment
2017
Francisco, Ana Paula | Nardocci, Adelaide Cássia | Tominaga, Maria Yumiko | da Silva, Camila Rodrigues | Assunção, João Vicente de
Thirty-five and eleven air samples were collected using, respectively, active samplers (filter + PUF) and passive samplers (PUF disks), over two consecutive four-month periods (spring and autumn-winter), in urban, urban/industrial, and rural (background) sites in São Paulo, Brazil. All the samples were extracted with toluene:acetone (9:1) in a Soxhlet apparatus, and the extracts were then purified. Analysis for polychlorinated dioxins and furans (PCDD/Fs) and for dioxin-like polychlorinated biphenyls (dl-PCBs) were made by High Resolution Gas Chromatography/High Resolution Mass Spectrometry (HRGC-HRMS). Human exposure risk was evaluated using inhalation risk assessment. Results showed: (1) there are statistical differences for PCDD/F concentrations in air between periods 1 and 2 (p = 0.03), whereas dl-PCB levels were not statistically different (p = 0.52); (2) PCDD/F and dl-PCB air levels were in the following order: urban/industrial > urban > rural for both active and passive samples; (3) PCDD/F and dl-PCB concentrations ranged from 7.76 to 453 fg TEQ/m³ in active air samples, and from 6.11 to 469 fg TEQ/m³ in passive air samples; (4) sampling rates for PCDD/Fs by the two approaches used showed considerable differences; (5) average daily intake by inhalation ranged from 18.1 to 55.6 fg TEQ/kg day, respectively, for adults and children, representing 1.8–5.6% of the lower range of the Tolerable Daily Intake recommended by the World Health Organization. Based on these results, the inhalation risk for PCDD/Fs and dl-PCBs, for local São Paulo residents, should be considered low.
Mostrar más [+] Menos [-]Accumulation of endocrine disrupting chemicals in the liver of Diplodus sargus sargus in Torre Guaceto Natural Reserve
2017
Rizzo, Daniela | Pennetta, Antonio | De Benedetto, Giuseppe E.
Studies on the quality of marine environments in Italy have traditionally favoured heavily impacted areas, such as harbours and industrial areas, while there are few investigations aimed at the evaluation of the presence of organic pollutants in the areas of marine reserve. The aim of this study was to determine endocrine-disrupting compounds (EDCs) in the liver of white seabreams (Diplodus sargus sargus) from the Natural Reserve of Torre Guaceto, Italy. Among EDCs, alkyl-phenols 2,6-DTBP, 2,4-DTBP, OP, and BPA were identified and quantified. The mean concentration of 2,6-DTBP, 2,4-DTBP, OP, and BPA were 2.2, 2.0, 1.2 and 3.6ng/g of liver, respectively, confirming the occurrence and transfer of these organic pollutants in the food web of marine organisms in marine reserves.
Mostrar más [+] Menos [-]Bio-effect-monitoring of long-term thermal wastes on the oyster, Crassostrea gigas, using heat shock proteins
2017
We bio-monitored the stress of oyster, Crassostrea gigas, for possible long term effects of thermal waste from a power plant. The expression level of its heat shock proteins (HSPs) was measured by real time-reverse transcript PCR along with their density and growth in the field. Oyster size varied in a distance dependent pattern. Physics modeling for evaluation of spreading of the thermal effluent revealed that station A is affected by the thermal effluents abundance, and the size of C. gigas showed a negative relationship with distance to the power plant. The abundance and size of C. gigas were smallest at station A, which was closest to the thermal effluent outlet. The kinetics of changes in the hsp70 and hsp90 mRNA levels in the mantle of C. gigas were also investigated. Regardless of the higher expression level of hsp70 mRNA than hsp90, both hsp70 and hsp90 mRNA levels were significantly higher at station A. The expression levels decreased inversely with distance from the thermal effluent outlet, with expression of hsp70 mRNA at station A being approximately 7-fold higher than at station B and 15-fold higher than at station C. Similarly, expression of hsp90 mRNA at station A was approximately 14-fold higher than at station B and 22-fold higher than at station C. The present findings provide new insights on biological correlation among the growth of individuals and population size and the molecular index in C. gigas following thermal effects.
Mostrar más [+] Menos [-]Management and environmental risk study of the physicochemical parameters of ballast water
2017
Shipping is a vital industry for the global economy. Stability of ships, provided by ballast water, is a crucial factor for cargo loading and unloading processes. Ballast water treatment has practical significance in terms of environmental issues, ecosystem, and human health, because ships discharge this water into the environment before loading their cargos. This study reviews the common methods for ballast water management – exchange, heating, filtration, ultrasonic treatment, ultraviolet irradiation, chemicals, and gas supersaturation – to select the best one. This study compares water temperature, salinity, dissolved oxygen, polycyclic aromatic hydrocarbons (PAHs), and heavy metals (Co, Cr, Ni, Pb) for ballast tanks of selected ships with the recipient port environment in the Persian Gulf as a case study. The exchange of ballast water in the ocean and/or its treatment on board to prevent inadvertent effects on the environment's physicochemical conditions is related to vessel characteristics, legislation, and the environmental condition. Ecological risk study showed that the salt content in ballast water is close to that of seawater, but the values of Cr (2.1mg/l) and Ni (0.029mg/l) in ballast water are higher than those in seawater (1 and 0.004mg/l, respectively).
Mostrar más [+] Menos [-]Geochemical markers of sedimentary organic matter in Todos os Santos Bay, Bahia – Brazil. Indicators of sources and preservation
2017
de Souza, José Roberto Bispo | do Rosário Zucchi, Maria | Costa, Alexandre Barreto | de Azevedo, Antonio Expedito Gomes | Spano, Saulo
Natural stable isotopes, such as carbon (C) and nitrogen (N), are modern tools to assess geochemical processes. C and N in organic matter can carry fingerprints of their hydrologic flows and sedimentary processes, including any anthropogenic modification on the natural system. This study focuses on the determination of aliphatic and polycyclic aromatic hydrocarbons and isotopic ratio in the sediment of Todos os Santos Bay (TSB). The isotopic results of the total organic matter indicate varied contribution marine and terrigenous. Typical rates of PAHs mainly indicate a pyrogenic source and mixture between pyrogenic and petrogenic sources. Typical ratios for the n-alkanes indicate the presence of petroleum hydrocarbons. The isotopic composition of n-alkanes suggests a mixture of sources, with the possible contribution of petrogenic.
Mostrar más [+] Menos [-]Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
2017
Rosset, Sabrina | Wiedenmann, Jörg | Reed, Adam J. | D'Angelo, Cecilia
Enrichment of reef environments with dissolved inorganic nutrients is considered a major threat to the survival of corals living in symbiosis with dinoflagellates (Symbiodinium sp.). We argue, however, that the direct negative effects on the symbiosis are not necessarily caused by the nutrient enrichment itself but by the phosphorus starvation of the algal symbionts that can be caused by skewed nitrogen (N) to phosphorus (P) ratios. We exposed corals to imbalanced N:P ratios in long-term experiments and found that the undersupply of phosphate severely disturbed the symbiosis, indicated by the loss of coral biomass, malfunctioning of algal photosynthesis and bleaching of the corals. In contrast, the corals tolerated an undersupply with nitrogen at high phosphate concentrations without negative effects on symbiont photosynthesis, suggesting a better adaptation to nitrogen limitation. Transmission electron microscopy analysis revealed that the signatures of ultrastructural biomarkers represent versatile tools for the classification of nutrient stress in symbiotic algae. Notably, high N:P ratios in the water were clearly identified by the accumulation of uric acid crystals.
Mostrar más [+] Menos [-]Expert elicitation for deriving input data for probabilistic risk assessment of shipwrecks
2017
The necessity of having a process in place for adequate risk assessment of shipwrecks that pose a threat to the marine environment is today internationally acknowledged. However, retrieving the desired data for such a risk assessment can prove challenging. One means of addressing this problem is to make use of experts' knowledge and experience. The purpose of this paper is therefore to present and analyse data for risk assessment of shipwrecks derived by expert elicitation. The main outcome is the experts' estimations of (i) the generic probability of an opening in a shipwreck due to the occurrence of a number of activities and (ii) estimations of the degree to which site-specific and wreck-specific indicators affect the probability of opening. Results show that the derived information is applicable in probabilistic shipwreck risk assessment and that the VRAKA framework now contains needed information for integrating generic and site-specific information using Bayesian updating.
Mostrar más [+] Menos [-]Does energetic cost for leaf construction in Sonneratia change after introduce to another mangrove wetland and differ from native mangrove plants in South China?
2017
Li, Fenglan | Yang, Lei | Zan, Qi-Jie | Shin, Paul-K.S. | Cheung, Siu-Gin | Wong, Yuk-Shan | Tam, Nora Fung-Yee | Lei, An-Ping
Exotic species invasions are serious ecological problems. Leaf construction cost (CC) and growth traits of two Sonneratia (Sonneratia caseolaris and S. apetala) and four native species (Bruguiera gymnorrhiza, Kandelia obovata, Aegiceras corniculatum and Avicennia marina) in Hainan and Shenzhen mangrove wetlands were compared to evaluate invasive potentials of Sonneratia after introduced to Shenzhen, their new habitat. There were no significant differences in CC and growth traits between two wetlands, suggesting Sonneratia did not lose any advantage in the new habitat and were competitive in both wetlands. CC per unit mass (CCM), CC per unit area (CCA) and caloric values of Sonneratia were significantly lower than those of native mangrove species while specific leaf area (SLA) was just the opposite. CCM of S. caseolaris and S. apetala were 6.1% and 11.9% lower than those of natives, respectively. These findings indicated the invasive potential of Sonneratia in Shenzhen after their introduction.
Mostrar más [+] Menos [-]Chemical composition and source apportionment of PM2.5 – A case study from one year continuous sampling in the Chang-Zhu-Tan urban agglomeration
2017
Tang, Xiangbo | Chen, Xiaohong | Tian, Yun
To understand the characteristics and source of atmospheric PM2.5 in Chang-Zhu-Tan urban agglomeration, PM2.5 samples were simultaneously collected at 11 monitoring sites within three cities of Changsha, Zhuzhou and Xiangtan from September 2013 to August 2014. Spatial and temporal variations of PM2.5 mass concentration and chemical compositions were analyzed based on the average values over the measurement sites in a specific urban area, including a comparison of PM2.5 at urban and urban background sites. Source apportionment was performed by PMF 5.0 (positive matrix factorization) model and potential source area affecting PM2.5 mass concentration was simulated using CWT (concentration-weighted trajectory analysis) analysis. The result showed the seasonal variation of PM2.5 mass concentration followed the order of winter > autumn > spring > summer. The OC/EC ratio in each season and each city were greater than 4.0, secondary inorganic ions accounted for at least 91% of the total water soluble inorganic ion concentration, presenting obvious secondary pollution characteristics. Coal combustion and vehicle emissions were two major sources of PM2.5 in all three cities, which accounted for about 35 percent and nearly 26 percent of contributions respectively. In addition, industrial emission and biomass burning were also significant sources in Changsha, while urban dust and biomass burning were significant sources in Zhuzhou and Xiangtan. Chang-zhu-tan urban agglomeration was the main source area of its PM2.5 and easy to form overlapping pollution areas. Meanwhile, northern neighboring city Yueyang and western bordering region Pingxiang also had a certain transmission influence on the formation of PM2.5.
Mostrar más [+] Menos [-]Microplastics in the Southern Ocean
2017
Isobe, Atsuhiko | Uchiyama-Matsumoto, Kaori | Uchida, Keiichi | Tokai, Tadashi
A field survey to collect microplastics with sizes <5mm was conducted in the Southern Ocean in 2016. We performed five net-tows and collected 44 pieces of plastic. Total particle counts of the entire water column, which is free of vertical mixing, were computed using the surface concentration (particle count per unit seawater volume) of microplastics, wind speed, and significant wave height during the observation period. Total particle counts at two stations near Antarctica were estimated to be in the order of 100,000pieceskm−2.
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