细化搜索
结果 931-940 的 2,503
Organochlorine pesticide content and distribution in coastal seafoods in Zhoushan, Zhejiang Province
2014
Wang, Jie-yu | Yu, Xin-wei | Fang, Li
Thirteen types of seafoods were collected from four counties (districts) of Zhoushan, Zhejiang Province, China and analyzed for organochlorine pesticides (OCPs). The average concentrations of OCPs in seafoods ranged from 258.3ngg−1 (lw) to 3459.6ngg−1 (lw). Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were the most abundant compounds in these environments and in total accounted for 8.2–62.2% and 32.1–89.0% of the total OCPs in seafoods, respectively. The total OCP contents were higher in seafoods from Shengsi and Putuo and lower in those from Dinghai and Daishan. The ratios of (DDE+DDD)/DDTs reflected a mixed input of accumulated and fresh DDTs in Shengsi, Putuo. The ratios of o,p′-DDT/p,p′-DDT in seafoods of Shengsi ranged 0.10–0.60 (mean 0.33), indicating that DDTs in seafoods of Shengsi may partly contain dicofol products and other pollutants accumulated in Yangtze Estuary. DDTs are a greater concern for ecotoxicological risk in the study area.
显示更多 [+] 显示较少 [-]Are changes in the structure of nematode assemblages reliable indicators of moderate petroleum contamination?
2014
Leite, Daniel Silva | Sandrini-Neto, Leonardo | Camargo, Manuela Zeglin | Thomas, Micheli Cristina | Lana, Paulo C.
This study assesses through a multiple before-after-control-impact (MBACI) design the effects of diesel oil on the structure of nematode assemblages in unvegetated tidal flats of a subtropical estuary. Oil-exposed treatments were contrasted with controls for a duration of four successive days before and after an experimental spill in three distinct areas of the Paranaguá Estuarine Complex (Southern Brazil). No significant differences were observed in nematode total density, number of taxa and the overall assemblage structure between the control and impact treatments from before to after the experimental spill. This reinforces the idea that, despite being good indicators of environmental stress, free-living marine nematodes are able to tolerate low concentrations of hydrocarbons and to survive in moderately contaminated areas. We also show that robust experimental designs are useful to avoid confounding expected natural variability with the effects of a mild impact.
显示更多 [+] 显示较少 [-]Carbonaceous particulate matter characterization in an urban and a rural site in the Philippines
2014
Bautista, Angel T. | Pabroa, Preciosa Corazon B. | Santos, Flora L. | Racho, Joseph Michael D. | Quirit, Leni L.
Concentrations of organic carbon (OC) and elemental carbon (EC) in PM2.5 were measured at an urban (Valenzuela City, Metro Manila) and a rural (Angat, Bulacan) site in the Philippines from September 2011 to August 2012 by thermal–optical reflectance analysis following IMPROVE–A protocol. Results show that OC (8.00μg m−3) and EC (6.63μg m−3) levels in Valenzuela were 2–3 times higher than those in Angat (OC: 4.08μg m−3, EC: 2.29μg m−3). The total carbon contributions (OC+EC) to PM2.5 mass for the urban and rural site were 38.9% and 19.7% respectively. Compared to neighboring countries in Asia, the Philippine sites have intermediate OC concentrations and greatly elevated EC levels. These suggest the presence of highly inefficient combustion sources and highlight the need for the regulation of such emissions. Valenzuela was dominated by OC2, OC3, and EC1 (carbon fractions evolving at 280°C and 480°C in pure He phase and 580°C in He/O2 phase of the analysis, respectively) which points to vehicular, industrial, and cooking sectors as the possible main sources. While generally having lower concentrations and being less EC–dominated, Angat had remarkably higher levels of the EC2 fraction which suggests a unique EC source in the area. Conditional Probability Function (CPF) for Valenzuela OC and EC show similar results pointing towards the 30°, 150°, and 210° direction, indicating common sources for these species. Detailed survey of the surrounding area is needed to ascertain the identities of the sources present in these directions.
显示更多 [+] 显示较少 [-]Volatile organic compound levels at one site in Rome urban air
2014
Fanizza, Carla | Incoronato, Federica | Baiguera, Silvia | Schiro, Roberto | Brocco, Domenico
Volatile organic compound (VOC), nitrogen dioxide (NO2) and ozone (O3) concentrations were measured at one site in Rome urban air during 2011. The seasonal mean concentrations of VOCs varied from 78μg m−3 in winter to 37μg m−3 in summer. Total aromatic concentration was reduced by 59% during summertime, alkanes of 39% and alkenes of 71%. VOC diurnal pattern exhibited a primary peak during the morning and a secondary peak in the evening hours coinciding with rush–hour traffic. The high correlation between benzene and toluene evidenced their common origin probably due to vehicular traffic. In summer isoprene diurnal profile showed both biogenic and anthropogenic origin. NO2 and O3 daily trends during summertime evidenced both photostationary state typical conditions and photochemical smog episodes. VOC and O3 trends also evidenced a reduction in VOC levels during O3 formation. Based on the Maximum Incremental Reactivity scale, the highest contributors to ozone production in Rome were propene, ethene and toluene. Comparing data found in Rome at the same site in 1992, 2007 and 2011, a decreasing trend in VOC levels was observed, suggesting the effectiveness of European Directives on air quality. In addition, our results were confirmed by similar data found in other urban areas around the world.
显示更多 [+] 显示较少 [-]Ambient particulate pollution during Chinese Spring Festival in urban Lanzhou, Northwestern China
2014
Zhao, Suping | Yu, Ye | Yin, Daiying | Liu, Na | He, Jianjun
The effect of firework displays on ambient particulate pollution in a typical valley city in Northwestern China was evaluated based on high temporal resolution atmospheric particle size distribution (10–10 000nm) data and particle mass concentrations in different sizes obtained during 25th January – 24th February, 2013. Firework displays have significant impact on particle number concentrations in accumulation mode (100–1 000nm), especially in 200–500nm, as well as PM1 mass concentrations. The hourly mean number concentration in 200–500 nm and PM1 mass concentration during the peak hour of firework displays were 11 800.2±2 548.0cm–3 and 214.1±31.2μg m−3, which are approximately 6 times and 2 times of that before the festival, respectively, with a maximum10–min mean number concentration in size range 100–1 000 nm reaching 3.8×104cm−3 on the New Year's Eve (00:10 BT 10th February, 2013). It was estimated that local emissions and firework displays contributed 74.6% and 37.0%, respectively, to the number concentration of particles less than 1 000nm. On short–time scale, the contribution of firework displays on local particulate pollution is obvious and should not be ignored, especially on fine particulate pollution.
显示更多 [+] 显示较少 [-]Partitioning behavior of perfluorinated compounds between sediment and biota in the Pearl River Delta of South China
2014
Zhao, Y.G. | Wan, H.T. | Wong, M.H. | Wong, Chris K.C.
Surface sediment and biota were collected from 12 sampling sites – seven along the Pearl River Delta and five along the Hong Kong coastline. Perfluorinated compound (PFC) concentrations were detected using a high-performance-liquid-chromatogram–tandem-mass-spectrometry system. Analytical results indicated that the total PFC concentrations were in the range of 0.15–3.11ng/g dry weight in sediments, while the total PFC concentrations in oyster and mussel samples were between 0.46–1.96 and 0.66–3.43ng/g wet weight, respectively. The major types of PFCs detected in the sediment samples were perfluorooctanesulfonic acid (PFOS) and perfluorobutanoic acid (PFBA), with concentrations ranging from low limits of quantification to 0.86±0.12ng/g dry weight and 1.50±0.26ng/g dry weight, respectively. In bivalve samples, PFOS was the dominant contaminant with concentrations ranging from 0.25±0.09 to 0.83±0.12ng/g wet weight in oysters and 0.41±0.14 to 1.47±0.25ng/g wet weight in mussels. An increase in PFC concentration was found to be correlated with increased human population density in the study areas.
显示更多 [+] 显示较少 [-]Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene
2014
Cai, P.-F. | Su, C.-J. | Chang, W. T. | Chang, F.-C. | Peng, C.-Y. | Sun, I-W. | Wei, Y.-L. | Jou, C.-J. | Wang, HPaul
Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag+-β-cyclodextrin complex at 573K for 30min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water.
显示更多 [+] 显示较少 [-]Vertical distribution of 241Pu in the southern Baltic Sea sediments
2014
Strumińska-Parulska, Dagmara I.
The vertical distribution of plutonium 241Pu in marine sediments can assist in determining the deposition history and sedimentation process of analyzed regions. In addition, 241Pu/239+240Pu activity ratio could be used as a sensitive fingerprint for radioactive source identification. The present preliminary studies on vertical distribution of 241Pu in sediments from four regions of the southern Baltic Sea are presented. The distribution of 241Pu was not uniform and depended on sediment geomorphology and depth as well as location. The highest concentrations of plutonium were found in the surface layers of all analyzed sediments and originated from the Chernobyl accident.
显示更多 [+] 显示较少 [-]Transcriptomic response to estrogen exposure in the male Zhikong scallop, Chlamys farreri
2014
An, Li-hui | Zheng, Bing-hui | Liu, Rui-zhi | Fan, Qiang | Wang, Qing-kui | Luo, Ying-feng
The transcriptomes of Zhikong scallop exposed to 17β-estradiol were determined using the Roche/454. A total of 51,997 unigenes, representing 45,030 contigs and 6967 singlets were obtained. And 14,028, 19,798 and 14,981 of these unigenes were annotated from the non-redundant nucleic acid database, non-redundant protein database and Swiss protein database, respectively. A total of 10,699 unigenes were further annotated to biological processes (9080), molecular functions (8692) and cellular components (7829) using the GO, and 8945 unigenes were mapped to biological pathways including the metabolism (2862) and genetic information processing (2263). Most importantly, 16,692 unigenes and 18,686 unigenes in testis, and 10,492 unigenes and 13,186 unigenes in digestive gland were up-regulated significantly after exposure to 50 and 500ngE2/L; while 10,212 unigenes and 9409 unigenes in testis and 10,629 unigenes and 9463 unigenes in digestive gland were down-regulated. These valuable information provides insights into the mechanisms in invertebrate exposure to EDCs.
显示更多 [+] 显示较少 [-]Sulfonamide antibiotics in the Northern Yellow Sea are related to resistant bacteria: Implications for antibiotic resistance genes
2014
Na, Guangshui | Zhang, Wanru | Zhou, Shiyao | Gao, Hui | Lu, Zihao | Wu, Xian | Li, Ruijing | Qiu, Lina | Cai, Yaqi | Yao, Ziwei
Antibiotic resistance gene (ARG) residues and the mode of transmission in marine environments remain unclear. The sulfonamide (SAs) concentrations, different genes and total bacterial abundance in seawater and sediment of the Northern Yellow Sea were analyzed. Results showed the genes sul I and sul II were present at relatively high concentrations in all samples, whereas the gene sul III was detected fewer. The ARGs concentrations in the sediment were 103 times higher than those in water, which indicated sediment was essential ARG reservoir. Statistical analysis revealed the total antibiotic concentration was positively correlated with the relative abundance of the gene sul I and sul II. The relative abundances of the gene sul I and the gene sul II were also correlated positively with those of the gene int1. This correlation demonstrated that SAs exerted selective pressure on these ARGs, whereas the gene int1 could be implicated in the propagation of the genes sul I and sul II in marine environments.
显示更多 [+] 显示较少 [-]