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Resultados 1021-1030 de 4,044
Effect of phytoplankton biomass in seawater on chemical properties of sea spray aerosols Texto completo
2016
Park, Jiyeon | Kim, Dohyung | Lee, Kwangyul | Han, Seunghee | Kim, Hyunji | Williams, Leah R. | Joo, Hung Soo | Park, Kihong
This study is to investigate the effect of biological seawater properties on sea spray aerosols (SSA). Concentrations of chlorophyll-a and bacteria were measured at coastal site in Korea in fall and summer seasons. Also, aerosol mass spectrometer (AMS) was used to determine chemical constituents (organics, sulfate, nitrate, ammonium, and chloride) of non-refractory submicrometer aerosols sprayed from seawaters using a bubble bursting system. The average concentration of chlorophyll-a in seawater in fall was 1.75±0.78μg/l, whereas it significantly increased to 5.11±2.16μg/l in summer. It was found that the fraction of organics in the submicrometer SSA was higher in summer (68%) than fall (49%), and that the organic fraction in the SSA increased as the concentration of chlorophyll-a increased in seawater, suggesting that the high phytoplankton biomass in seawater could lead to the enhancement of organic species in the SSA.
Mostrar más [+] Menos [-]Ballast water sediment elemental analysis Texto completo
2016
Maglić, Lovro | Zec, Damir | Frančić, Vlado
Sediment samples from the ballast water tanks of ships calling at the port of Rijeka in the Northern Adriatic were analysed using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) using caesium, argon and oxygen ion beams. The research was carried out in order to determine the sediment composition and relative abundance of the dominant elements. The results indicate that the sediment samples mostly consisted of compounds that originated from the deterioration of tank plates, tank coating residues and ballast operations such as clay, silt, sand and organic materials. No significant heavy metals or highly toxic elements were found. The research revealed some advantages and significant drawbacks of using XPS and SIMS for the routine analysis of sediment composition as a decision supporting tool for ballast water and sediment management.
Mostrar más [+] Menos [-]Assessment of heavy metal contamination in the surface sediments: A reexamination into the offshore environment in China Texto completo
2016
Chen, Hongzhe | Wang, Jigang | Chen, Jinmin | Lin, Hui | Lin, Cai
The contents of Cu, Pb, Zn, Cd, Cr, Hg and As in the surface sediments of over 668 sites were monitored in a comprehensive program for assessing the degree of heavy-metal pollution and adverse biological effects of the offshore sediments in China. The contamination factor and geoaccumulation index indicated that As and Pb might be two of the most influential pollution loading in these metals. Cluster analysis separated 19 areas in China's near seas into 7 groups with different pollution characteristic, where the sediments along Zhejiang coast were the most highly-contaminated. Based on biological adverse effects index and sediment quality guideline for As, nearly half of sites in China's near seas induced slight adverse biological effects. With correlation analysis, self-organizing map and factor analysis, different sources as well as various adsorption mechanisms/anthropogenic factors were suggested to be important roles in altering the concentration of heavy metals in the sediments.
Mostrar más [+] Menos [-]Assessment of vertical element distribution in street canyons using the moss Sphagnum girgensohnii: A case study in Belgrade and Moscow cities Texto completo
2016
Goryainova, Zoya | Vuković, Gordana | Uros̆ević, Mira Aničić | Vergel, Konstantin | Ostrovnaya, Tatyana | Frontasyeva, Marina | Zechmeister, Harald
Sphagnum girgensohnii moss bags were used to study the small-scale vertical distribution of some major and trace elements in different types of street canyons (regular, deep and avenue types) in Belgrade and Moscow urban area. The exposure time was 10 weeks during the summer of 2011. The exposure of moss bags was at three different levels to test differences in deposition patterns according to height. The differences between the street and off-street side in the vertical element distribution in Moscow were tested too. The concentration of 25 major and trace elements in moss was determined by instrumental neutron activation analysis. The results showed that the accumulation of elements in the exposed moss bags were higher in deep and regular street canyons in comparison to that of the avenue type, the latter even with a higher traffic flow. The element concentrations were the highest at the lowest heights compared to those of the upper floors. For most determined elements the concentrations were lower on the off-street avenue side compared to the on-street side for all heights of moss exposure. The results obtained indicate that S. girgensohnii is sensitive to small-scale variations of the total concentrations of elements.
Mostrar más [+] Menos [-]Seasonal and spatial variations of water quality and trophic status in Daya Bay, South China Sea Texto completo
2016
Wu, Mei-Lin | Wang, You-Shao | Wang, Yu-Tu | Sun, Fu-Lin | Sun, Cui-Ci | Cheng, Hao | Dong, Jun-De
Coastal water quality and trophic status are subject to intensive environmental stress induced by human activities and climate change. Quarterly cruises were conducted to identify environmental characteristics in Daya Bay in 2013. Water quality is spatially and temporally dynamic in the bay. Cluster analysis (CA) groups 12 monitoring stations into two clusters. Cluster I consists of stations (S1, S2, S4–S7, S9, and S12) located in the central, eastern, and southern parts of the bay, representing less polluted regions. Cluster II includes stations (S3, S8, S10, and S11) located in the western and northern parts of the bay, indicating the highly polluted regions receiving a high amount of wastewater and freshwater discharge. Principal component analysis (PCA) identified that water quality experience seasonal change (summer, winter, and spring–autumn seasons) because of two monsoons in the study area. Eutrophication in the bay is graded as high by Assessment of Estuarine Trophic Status (ASSETS).
Mostrar más [+] Menos [-]An integrative biomarker approach to assess the environmental stress in the north coast of Shandong Peninsula using native oysters, Crassostrea gigas Texto completo
2016
Xie, Jia | Zhao, Yun | Wang, Qing | Wu, Huifeng | Teng, Jia | Yang, Dinglong | Cao, Ruiwen | Chen, Lizhu | Zhang, Yingjun | Li, Fei | Ji, Chenglong | Cong, Ming | Zhao, Jianmin
An integrative biomarker approach was employed to evaluate the environmental quality of the north coast of Shandong Peninsula along the southern Bohai Sea of China, where pollution is an imminent threat due to rapid urbanization and industrialization. A battery of biomarkers and the metal bioaccumulation in tissues of native oyster Crassostrea gigas were measured under field conditions. Integrative biomarker index (IBR) and metal body burden were calculated to differentiate the pollution status of seven sampling sites. According to our results, Xinzhuang (XZ) site was the most severely contaminated, with the highest IBR value of 3.58, while the lowest IBR value (0.04) was obtained at Penglai (PL). Such an integrated biomarker approach was proved as a useful method for environmental quality assessment in the study area.
Mostrar más [+] Menos [-]Depositional time trends of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in a dated sediment core from the Northern Arabian Gulf Texto completo
2016
Gevao, Bondi | Bahloul, Majed | Guijarro, Karell Martinez | Kannan, Kurunthachalam
The historical record of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) deposition was reconstructed from the analysis of a dated sediment core collected from a remote area in the northwestern Arabian Gulf not influenced by any point sources of contamination. The sedimentary record showed that PCDD/F concentrations started to increase above pre-industrial background levels in the mid-1960s. This was followed by an exponential increase in concentrations attaining a maximum of 7.5pg/g (dry wt) in the early 1980s and stayed fairly constant thereafter. The homolog profiles in sediments remained fairly consistent throughout the core with PCDD contributing 75% of the ΣPCDD/F concentrations. The homolog profile was dominated by OCDD which contributed approximately 55% of the total dioxins throughout the core. The consistency in the homolog patterns throughout the core suggests that the source of dioxins have remained fairly unchanged throughout the sedimentary record represented by the core.
Mostrar más [+] Menos [-]First evidence on the occurrence and dynamics of Dehalococcoides mccartyi PCB-dechlorinase genes in marine sediment during Aroclor1254 reductive dechlorination Texto completo
2016
Matturro, B. | Di Lenola, M. | Ubaldi, C. | Rossetti, S.
The present study evaluates the PCB-dehalorespiring capabilities and dynamics of indigenous Dehalococcoides mccartyi population in a PCB contaminated marine sediment. Specialized PCB-dechlorinase genes pcbA1, pcbA4 and pcbA5 previously characterized in pure cultures of D. mccartyi, were here found for the first time in environmental samples. Reductive dechlorination was stimulated by spiking Aroclor1254 to the sediment and by imposing strictly anaerobic conditions both with and without bioaugmentation with a Dehalococcoides mccartyi enrichment culture. In line with the contaminant dechlorination kinetics, Dehalococcoides population increased during the entire incubation period showing growth yields of 4.94E+07 Dehalococcoides per μmolCl−1 and 7.30E+05 Dehalococcoides per μmolCl−1 in the marine sediment with and without bioaugmentation respectively. The pcbA4 and pcbA5 dechlorinase genes, and to a lesser extent pcbA1 gene, were enriched during the anaerobic incubation suggesting their role in Aroclor1254 dechlorination under salinity conditions.
Mostrar más [+] Menos [-]Trace metals in the surface sediments of the intertidal Jiaozhou Bay, China: Sources and contamination assessment Texto completo
2016
Xu, Fangjian | Qiu, Longwei | Cao, Yingchang | Huang, Jingli | Liu, Zhaoqing | Tian, Xu | Li, Anchun | Yin, Xuebo
The major (Al) and trace metal (Cu, Pb, Zn, Cr, Cd, and As) concentrations in 29 surface sediment samples from the intertidal Jiaozhou Bay (JZB) are evaluated to assess the contamination level. The results show that the overall sediment quality in the area has been obviously impacted by trace metal contamination. The geoaccumulation index and the enrichment factor values indicate that no Cr or Cu contamination has occurred on the whole, only a few stations have been polluted by As, and some areas have been polluted by Cd, Pb, and Zn. Principal component analysis suggests that the Cu, Pb, Zn, and Cd are derived from anthropogenic inputs and that Cr, As, Cu, and Zn are influenced by natural weathering processes. Cu and Zn may originate from both natural and anthropogenic sources. The contamination in the northeastern JZB is higher than that in other areas of the bay.
Mostrar más [+] Menos [-]A baseline study of coastal water quality in the Lembeh Strait of North Sulawesi, Indonesia, in 2013 Texto completo
2016
Baohong, Chen | Muchtar, Muswerry | Tingting, Fu | Hongzhe, Chen | Jigang, Wang | Kaiwen, Zhou | Jianguo Du, | Kuai, Lin | Bin, Chen
The concentrations of nutrients (NO2–N, NO3–N, NH4–N, PO4–P, and SiO3–Si) and their ratios in the Lembeh Strait were estimated in April 2013, off the northeastern coast of Sulawesi in Indonesia. The concentrations of dissolved inorganic nitrogen (DIN) (NO2–N+NO3–N+NH4–N) and PO4–P were low, with a maximum of 0.181 and 0.007mg/L, respectively. P was found to be the limiting factor controlling phytoplankton growth overall. According to a potential eutrophication assessment model, both the surface water and the water at a depth of 15m were classified as water 1 (poor nutrition). This study provides baseline information including chemical datasets for future pollution monitoring and management programs in this area.
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