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Resultados 1301-1310 de 4,042
Organic matter quantity and quality, metals availability and foraminiferal assemblages as environmental proxy applied to the Bizerte Lagoon (Tunisia) Texto completo
2016
Martins, Maria Virgínia Alves | Helali, Mohamed Amine | Zaaboub, Noureddine | Boukef-BenOmrane, Imen | Frontalini, Fabrizio | Reis, Darlly | Portela, Helena | Clemente, Iara Martins Matos Moreira | Nogueira, Leandro | Pereira, Egberto | Miranda, Paulo | El Bour, Monia | Aleya, Lotfi
This study analyzes the benthic trophic state of Bizerte Lagoon (Tunisia) based on the total organic matter and the bioavailability of biopolymeric carbon including proteins (PTN), carbohydrates (CHO), lipids (LIP), chlorophyll a, as well as bacteria counts. The overall simultaneously extracted metals (SEM), and acid volatile sulfides (AVS) as well as the SEM/AVS ratio indicative of the toxicity of the sediments also were analyzed aiming to study their impact in the dimension, composition and structure of both dead and living benthic foraminiferal assemblages.In the studied sites TOC content is relatively high and the PTN/CHO values indicate that they can be considered as meso-eutrophic environments. The CHO/TOC and C/N values suggest that the OM which accumulated on the sediments surface has mainly natural origin despite the introduction of municipal and industrial effluents in the lagoon and the large bacterial pool.The living assemblages of benthic foraminifera of Bizerte Lagoon are quite different to other Mediterranean transitional systems studied until now. They are composed of typical lagoonal species but also include several marine and opportunistic species including significant numbers of bolivinids, buliminids, Nonionella/Nonionoides spp. and Cassidulina/Globocassidulina spp. These assemblages seem to benefitfrom the physicochemical parameters and the sediment stability. They may however face environmental stress in the lagoon related to the AVS production as a result of the organic matter degradation and toxicity in some areas due to the available concentrations of metals. Nonetheless statistical results evidence that the structure and dimension of assemblages are being controlled mostly by OM quantity and quality related mainly to the availability of PTN, CHO and chlorophyll a. Results of this work support the importance of considering OM quantity and quality in studies of environmental impact in coastal systems.
Mostrar más [+] Menos [-]Pressure on oxygen levels of Jakarta Bay Texto completo
2016
Ladwig, Norbert | Hesse, Karl-J. | van der Wulp, Simon A. | Damar, Ario | Koch, Daniela
Jakarta Bay is subject to inputs of large amounts of dissolved inorganic nutrients and organic matter deriving from the Jakarta Metropolitan Area and its hinterland. As a consequence, inorganic and organic nutrient concentrations in the nearshore area are considerably increased. The hydrographic pattern inside the bay fosters phytoplankton bloom formation due to pronounced vertical density gradients. High Biomass Blooms (HBB) of phytoplankton are observed recurrently, representing an additional source for oxygen consuming degradable organic matter. An oxygen deficiency area of 20km2 can be identified in the eastern part of Jakarta Bay where oxygen levels decrease to 60% saturation, equaling a noxiously low concentration of 4.0mg·dm−3 O2. The absolute minimum detected was 51% O2 or 3.2mg·dm−3 O2. The observed oxygen concentrations fail Indonesian quality standards for seawater.
Mostrar más [+] Menos [-]Origins of suspended particulate matter based on sterol distribution in low salinity water mass observed in the offshore East China Sea Texto completo
2016
Kim, Moonkoo | Jung, Jee-hyun | Jin, Yongnu | Han, Gi Myeong | Lee, Taehee | Hong, Sang Hee | Yim, Un Hyuk | Shim, Won Joon | Choi, Dong-Lim | Kannan, Narayanan
The molecular composition and distribution of sterols were investigated in the East China Sea to identify the origins of suspended particulate matter (SPM) in offshore waters influenced by Changjiang River Diluted Water (CRDW). Total sterol concentrations ranged from 3200 to 31,900pgL−1 and 663 to 5690pgL−1 in the particulate and dissolved phases, respectively. Marine sterols dominated representing 71% and 66% in the particulate and dissolved phases, respectively. Typical sewage markers, such as coprostanol, were usually absent at ~250km offshore. However, sterols from allochthonous terrestrial plants were still detected at these sites. A negative relationship was observed between salinity and concentrations of terrestrial sterols in SPM, suggesting that significant amounts of terrestrial particulate matter traveled long distance offshore in the East China Sea, and the Changjiang River Diluted Water (CRDW) was an effective carrier of land-derived particulate organic matter to the offshore East China Sea.
Mostrar más [+] Menos [-]Coral Sr/Ca-based sea surface temperature and air temperature variability from the inshore and offshore corals in the Seribu Islands, Indonesia Texto completo
2016
Cahyarini, Sri Yudawati | Zinke, Jens | Troelstra, Simon | Suharsono, | Aldrian, Edvin | Hoeksema, B.W.
The ability of massive Porites corals to faithfully record temperature is assessed. Porites corals from Kepulauan Seribu were sampled from one inshore and one offshore site and analyzed for their Sr/Ca variation. The results show that Sr/Ca of the offshore coral tracked SST, while Sr/Ca variation of the inshore coral tracked ambient air temperature. In particular, the inshore SST variation is related to air temperature anomalies of the urban center of Jakarta. The latter we relate to air—sea interactions modifying inshore SST associated with the land-sea breeze mechanism and/or monsoonal circulation. The correlation pattern of monthly coral Sr/Ca with the Niño3.4 index and SEIO-SST reveals that corals in the Seribu islands region respond differently to remote forcing. An opposite response is observed for inshore and offshore corals in response to El Niño onset, yet similar to El Niño mature phase (December to February). SEIO SSTs co-vary strongly with SST and air temperature variability across the Seribu island reef complex. The results of this study clearly indicate that locations of coral proxy record in Indonesia need to be chosen carefully in order to identify the seasonal climate response to local and remote climate and anthropogenic forcing.
Mostrar más [+] Menos [-]Characteristics and source apportionment of VOCs in the suburban area of Beijing, China Texto completo
2016
Wang, Gang | Cheng, Shuiyuan | Wei, Wei | Zhou, Ying | Yao, Sen | Zhang, Hanyu
The measurement of volatile organic compounds (VOCs) was conducted during November 2014 in the suburban area of Beijing, China, covering the period of the Asia-Pacific Economic Cooperation (APEC) meeting period. The VOCs characteristics and source apportionment were analyzed. The average mass concentrations of VOCs were 27.6 ± 19.7 μg/m3 during the sampling period, and aromatics and alkanes were the most abundant VOCs species in atmospheric environment in Beijing which were 12.2 ± 10.3 μg/m3 and 11.3 ± 7.5 μg/m3, respectively. The hourly variation of VOCs was found, with the highest concentration occurring at 8:00 to 9:30 and lowest at 12:30 to 14:00. The sampling period was divided into two periods: period Ⅰ represent the period without emission-reduction measures, and period Ⅱ represent the period with reduction measures. The VOCs concentrations during the period Ⅱ was 31.0% lower than period Ⅰ. The Maximum Incremental Reactivity (MIR) method was applied to analysis the ozone formation potential (OFP). The OFP of VOCs from period Ⅰ was 1.6 times higher than period Ⅱ, and the majority of VOCs species were alkenes and aromatics. Positive matrix factorization was applied to estimate contributions of potential VOCs sources. The vehicle exhaust emission was the major source of VOCs during the two periods, and the contribution to VOCs was 5.7% lower during period Ⅱ than period Ⅰ due to the emission-reduction of vehicle operation.
Mostrar más [+] Menos [-]FTIR spectroscopy supported by statistical techniques for the structural characterization of plastic debris in the marine environment: Application to monitoring studies Texto completo
2016
Mecozzi, Mauro | Pietroletti, Marco | Monakhova, Yulia B.
We inserted 190 FTIR spectra of plastic samples in a digital database and submitted it to Independent Component Analysis (ICA) to extract the “pure” plastic polymers present. These identified plastics were polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), high density polyethylene terephthalate (HDPET), low density polyethylene terephthalate (LDPET), polystyrene (PS), Nylon (NL), polyethylene oxide (OPE), and Teflon (TEF) and they were used to establish the similarity with unknown plastics using the correlation coefficient (r), and the crosscorrelation function (CC). For samples with r<0.8 we determined the Mahalanobis Distance (MD) as additional tool of identification. For instance, for the four plastic fragments found in the Carretta carretta, one plastic sample was assigned to OPE due to its r=0.87; for all the other three plastic samples, due to the r values ranging between 0.83 and0.70, the support of MD suggested LDPET and OPE as co-polymer constituents.
Mostrar más [+] Menos [-]Identification of Pb sources using Pb isotopic compositions in the core sediments from Western Xiamen Bay, China Texto completo
2016
Yu, Ruilian | Hu, Gongren | Yang, Qiuli | He, Haixing | Lin, Chengqi
Pb concentrations and Pb isotopic compositions (total and acid-extractable) in the core sediments collected from Western Xiamen Bay, China, were determined to investigate the Pb pollution history and trace the Pb sources. Pb concentration showed an increasing trend (from 40.3 to 64.2mgkg−1) with obvious fluctuation from 1967 to 2013, reflected by the core sediments. The enrichment factors of Pb were between 2 and 5, indicating a moderate enrichment. The relative contributions of Pb-Zn deposit and parent material to total Pb in the core sediments were 51%–62% and 38%–49%, respectively. Acid-extractable Pb isotopic signature was more sensitive than total Pb isotopic signature in identifying anthropogenic Pb sources due to the substantial variability of acid-extractable Pb isotopic ratios exhibited in the core sediments. Based on the acid-extractable Pb isotopic ratios, Pb-Zn deposit and industrial emission were regarded as the main anthropogenic Pb contributors.
Mostrar más [+] Menos [-]Fate, behaviour and weathering of priority HNS in the marine environment: An online tool Texto completo
2016
Cunha, Isabel | Silva, Helena Oliveira da | Neuparth, Teresa | Torres, Tiago | Santos, Miguel Machado
Literature data and data obtained with modelling tools were compiled to derive the physicochemical behaviour of 24 priority Hazardous and Noxious Substances (HNS), as a proxy to improve environmental, public health and political issues in relation to HNS spills. Parameters that rule the HNS behaviour in water and those that determine their distribution and persistence in the environment, such as fugacity, physicochemical degradation, biodegradation, bioaccumulation/biotransformation and aquatic toxicity, were selected. Data systematized and produced in the frame of the Arcopol Platform project was made available through a public database (http://www.ciimar.up.pt/hns/substances.php). This tool is expected to assist stakeholders involved in HNS spills preparedness and response, policy makers and legislators, as well as to contribute to a current picture of the scientific knowledge on the fate, behaviour, weathering and toxicity of priority HNS, being essential to support future improvements in maritime safety and coastal pollution response before, during and after spill incidents.
Mostrar más [+] Menos [-]Hazards in hanging gardens: A report on failures of recognition by green turtles and their conservation implications Texto completo
2016
de Carvalho-Souza, Gustavo Freire | de A. Miranda, Daniele | Pataro, Luciano
Marine species are experiencing unprecedented global impacts due to anthropogenic debris. Many recent studies have pointed out the hazards associated with marine litter ingestion, especially plastic debris – the most abundant and ubiquitous items in coastal and oceanic environments worldwide. In this study we provide the first in situ evidence of consumption of non-discarded synthetic rope fragments by green turtles. We explored the environmental risks to this endangered species associated with the grazing and consumption of anthropogenic debris in zones of human activity. Efforts to combat debris ingestion and reduce anthropogenic debris discharged into the world's oceans should be a priority for decision-makers and will need to involve multiple-approaches and the adoption of more environmentally friendly products and practices by the international community.
Mostrar más [+] Menos [-]Polybrominated diphenyl ethers (PBDEs) in mussels from cultures and natural population Texto completo
2016
Dosis, Ioannis | Athanassiadis, Ioannis | Karamanlis, Xanthippos
Polybrominated diphenyl ether (PBDE) mass fractions were determined in mussel samples collected from 6 locations around Thermaikos Gulf in north Greece. PBDEs were present in all sampling sites and the average total (ΣPBDEs) ranged from 17.7 to 32.3ng/g l.w., characterising Thermaikos as low polluted, a fact further supported by congener ratios and literature comparison. Distribution was even among stations with one exception. Congener profiles exhibited predominance of penta-/octa-BDEs as well as BDE-209. Statistical analysis showed significant difference in pollution levels between the two types of mussel cultures. No variations were observed for mussel bunch position or between cultures and natural population. Congener correlation analysis suggested different pollution sources between higher and lower brominated congeners as well as different metabolic/degradation processes. Bioaccumulation factors indicated that an increase in congener bromination degree leads to bioaccumulation capacity reduction. Consumption of mussels from Thermaikos gulf area poses no threat for public health concerning PBDEs.
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