خيارات البحث
النتائج 1701 - 1710 من 3,208
Polycyclic aromatic hydrocarbons in the largest deepwater port of East China Sea: impact of port construction and operation النص الكامل
2015
Li, Juan-Ying | Cui, Yu | Su, Lei | Chen, Yiqin | Jin, Ling
PAHs were analyzed for samples of seawater, sediment, and oyster (Saccostrea cucullata) collected from Yangshan Port, East China between 2012 and 2013. Concentrations of ∑PAHs in seawater (180–7,700 ng/L) and oyster (1,100–29,000 ng/g dry weight (dw)) fell at the higher end of the global concentration range, while sediment concentrations (120–780 ng/g dw) were generally comparable to or lower than those reported elsewhere. PAHs in the particulate phase accounted for 85 % (52–93 %) of the total PAHs in seawater. Congener profile analysis revealed that PAHs in waters originate mainly from petrogenic sources, while high-temperature combustion processes are the predominant sources for sediment. ∑PAHs in oyster well correlated with ∑PAHs in the particulate phase, suggesting particle ingestion as an important pathway for bioaccumulation of PAHs. Cancer risk assessment of PAHs in oyster indicated high human health risks posed by these chemicals to the coastal population consuming this seafood.
اظهر المزيد [+] اقل [-]PFOS and PFOA in paired urine and blood from general adults and pregnant women: assessment of urinary elimination النص الكامل
2015
Zhang, Tao | Sun, Hongwen | Qin, Xiaolei | Gan, Zhiwei | Kannan, Kurunthachalam
Although levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in human blood are well documented, information on elimination of these chemicals is limited. In this study, PFOS and PFOA were analyzed in 81 whole blood–urine paired samples from general adults and pregnant women in Tianjin, China. PFOS and PFOA were detected in 48 and 76 % of adult urine (AU) samples, with geometric mean (GM) concentrations of 0.011 and 0.008 ng/mL, respectively; whereas relatively low PFOS and PFOA concentrations were found in maternal urine (MU) samples, with GM concentrations of 0.006 and 0.003 ng/mL, respectively. For PFOA, the coefficients of Pearson’s correlation between whole blood concentrations and creatinine-adjusted and creatinine-unadjusted urinary concentrations were 0.348 (p = 0.013) and 0.417 (p = 0.002), respectively. The GM urinary elimination rates of PFOS (PFOSUER) and PFOA (PFOAUER) were 16 and 25 %, respectively, for adults. These results indicate that urine is an important pathway of excretion of perfluoroalkyl substances (PFASs). The partitioning ratios of PFAS concentration between urine and whole blood (PFASU/B) in pregnant women (PFOSU/B, 0.0004; PFOAU/B, 0.0011) were significantly lower (p = 0.025 for PFOSU/B, p = 0.017 for PFOAU/B) than the ratios found in non-pregnant women (PFOSU/B, 0.0013; PFOAU/B, 0.0028). Furthermore, our results suggest a clear gender difference in the urinary elimination of PFOA, with male adults (31 %) having significantly higher PFOAUERthan that of female adults (19 %). PFOSUERwas significantly inversely correlated with age (r = −0.334, p = 0.015); these findings suggest that urinary elimination of PFOS is faster in young adults than in the elderly.
اظهر المزيد [+] اقل [-]Model for photodegradation of polybrominated diphenyl ethers النص الكامل
2015
Vesely, M. | Vajglova, Z. | Kotas, P. | Kristal, J. | Ponec, R. | Jiricny, V.
Polybrominated diphenyl ethers (PBDE) were, and in some countries still are, used as flame retardants for plastic materials. When released from plastics, PDBE cause harm to the environment. This creates the incentive for further investigation of the PBDE degradation. This work focused on a formulation of a PBDE photodegradation model based on the PBDE properties obtained by the quantum chemical calculations. The proposed model predicted degradation routes of arbitrary PBDE congener. The routes of selected congeners were validated by the two independently published data sets and showed the high fitting degree. The model can be easily modified for any reactor system if the initial reaction rate constant of one congener is available for the given system.
اظهر المزيد [+] اقل [-]Occurrence of pharmaceuticals in municipal wastewater, in the recipient water, and sedimented particles of northern Lake Päijänne النص الكامل
2015
Lindholm-Lehto, Petra C. | Ahkola, Heidi S. J. | Knuutinen, Juha S. | Herve, Sirpa H.
The presence of five different pharmaceuticals, consisting of four anti-inflammatory and one antiepileptic drug, was determined in influent and effluent of a municipal wastewater treatment plant (WWTP) near the city of Jyväskylä, Finland, and in the receiving water, northern Lake Päijänne. In addition, samples of sedimented particles were collected among water samples from five locations near the discharge point of the treated wastewater. The solid phase extracts (SPEs) of water samples were analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in the multiple reaction monitoring mode. The studied pharmaceuticals were detected from influent, effluent, and lake water but also in the sedimented particles. The concentrations of carbamazepine, diclofenac, ibuprofen, ketoprofen, and naproxen in Lake Päijänne ranged from 1 to 21 ng L⁻¹, 4 to 209 ng L⁻¹, 5 to 836 ng L⁻¹, 9 to 952 ng L⁻¹, and 2 to 129 ng L⁻¹, respectively. The concentrations of ketoprofen in sedimented particles ranged from 79 to 135 μg g⁻¹ while only trace amounts of other selected pharmaceuticals were detected. The results indicate that the concentrations of pharmaceuticals are affected by the biological and chemical reactions occurring in the wastewater treatment processes but also by the UV light in the photic layer of Lake Päijänne. It can be concluded that considerable amount of selected pharmaceuticals are present in the influent and effluent of municipal WWTP but also in the water phase and sedimented particles of northern Lake Päijänne.
اظهر المزيد [+] اقل [-]Relationship between viral detection and turbidity in a watershed contaminated with group A rotavirus النص الكامل
2015
Assis, Andrêssa Silvino Ferreira | Cruz, Lucas Taffarel | Ferreira, Aline Siqueira | Bessa, Martha Eunice | de Oliveira Pinto, Miriam Aparecida | Vieira, Carmen Baur | Otenio, Marcelo Henrique | Miagostovich, Marize Pereira | da Rosa e Silva, Maria Luzia
Enteric viruses are present in aquatic environments due to contamination by raw sewage, even in the absence of fecal coliforms, which are considered to be significant indicators when it comes to microbial water quality assessment. This study investigated the presence of group A rotavirus (RVA) in surface water from a river basin in Minas Gerais, Brazil, assessing the influence of the urbanization, the rainfall, and the microbiological and physico-chemical parameters regarding water quality. Forty-eight surface water samples collected in urbanized and non-urbanized areas, both in dry and rainy periods, were obtained throughout the study. The viral particles were concentrated by adsorption-elution in a negatively charged membrane. Fecal coliforms, as well as physico-chemical water parameters were determined at each point in all collections. The RVA was detected in 62.5 % (30/48) of the water samples through a real-time PCR assay. All the sequenced RVA strains belonged to genotype I1. The RVA was detected in 50.0 % (11/22) of the water samples regarded as being acceptable by current microbiological standards. The presence of the RVA and the viral load were influenced by the collection area (p < 0.05). It was also observed a significant association between the RVA and detecting the turbidity of water (p < 0.05). The collected data showed a high level of contamination in this watershed by the discharge of raw sewage, highlighting the need for urgent measures to improve water quality, ensuring the safe use of this matrix.
اظهر المزيد [+] اقل [-]Sequential anaerobic/anaerobic digestion for enhanced sludge stabilization: comparison of the process performance for mixed and waste sludge النص الكامل
2015
Tomei, M Concetta | Carozza, Nicola Antonello
Sequential anaerobic-aerobic digestion has been demonstrated as a promising alternative for enhanced sludge stabilization. In this paper, a feasibility study of the sequential digestion applied to real waste activated sludge (WAS) and mixed sludge is presented. Process performance is evaluated in terms of total solid (TS) and volatile solid (VS) removal, biogas production, and dewaterability trend in the anaerobic and double-stage digested sludge. In the proposed digestion lay out, the aerobic stage was operated with intermittent aeration to reduce the nitrogen load recycled to the wastewater treatment plant (WWTP). Experimental results showed a very good performance of the sequential digestion process for both waste and mixed sludge, even if, given its better digestibility, higher efficiencies are observed for mixed sludge. VS removal efficiencies in the anaerobic stage were 48 and 50 % for waste and mixed sludge, respectively, while a significant additional improvement of the VS removal of 25 % for WAS and 45 % for mixed sludge has been obtained in the aerobic stage. The post-aerobic stage, operated with intermittent aeration, was also efficient in nitrogen removal, providing a significant decrease of the nitrogen content in the supernatant: nitrification efficiencies of 90 and 97 % and denitrification efficiencies of 62 and 70 % have been obtained for secondary and mixed sludges, respectively. A positive effect due to the aerobic stage was also observed on the sludge dewaterability in both cases. Biogas production, expressed as Nm³/(kgVSdₑₛₜᵣₒyₑd), was 0.54 for waste and 0.82 for mixed sludge and is in the range of values reported in the literature in spite of the low anaerobic sludge retention time of 15 days.
اظهر المزيد [+] اقل [-]An approach to determination of optimal species pool of periphytic microfauna in colonization surveys for marine bioassessment النص الكامل
2015
Xu, Guangjian | Zhong, Xiaoxiao | Wang, Yangfan | Xu, Henglong
To determine an optimal species pool for periphytic microfauna colonization surveys, a multivariate approach was used to identify the influential species from a raw dataset of periphytic microfauna. Samples were collected at two depths of 1 and 3 m in coastal waters of the Yellow Sea using a glass slide method. From the full 77-species dataset, a 23-species subset with sufficient information of the whole community was identified. The small subset maintained sufficient information of colonization pattern of entire raw communities (correlation coefficient >0.95). The colonization curves based the small subset well fitted the MacArthur-Wilson and logistic model equations in both species composition and individual abundance, respectively. Compared to the functional parameters based on the full dataset, the colonization rates (G) were significantly high and the time reaching 90 % equilibrium species number (T₉₀) significantly low (P < 0.05), while the growth rates (r) and the time reaching 50 % maximum abundance (T₅₀) showed no significant changes (P > 0.05) at both depths, respectively. The species richness, diversity, and evenness represented significantly closed linear relationships between the subset and the full dataset. The results suggest that the small subset might be used as a robust optimal species pool for colonization-based bioassessment surveys and allows developing a time-efficient protocol for marine monitoring programs using of periphytic microfauna.
اظهر المزيد [+] اقل [-]Impact of reference geosorbents on oral bioaccessibility of PAH in a human in vitro digestive tract model النص الكامل
2015
Meyer, Wiebke | Kons, Sandra | Achten, Christine
Former studies on human oral bioaccessibility of polycyclic aromatic hydrocarbons (PAH) from natural soil samples using human in vitro digestive tract models (physiologically based extraction tests, PBET) show highly variable results (0–100 % of mobilized PAH). Apart from other factors, the type and amount of present geosorbents are assumed to be significant for the degree of desorption/release of PAH into the digestive juice. Therefore, in this study, the reference geosorbents pure quartz sand, Na-montmorillonite clay, Pahokee peat, and charcoal “Sommerhit” were spiked with selected deuterated PAH and employed as single materials in a PBET. Lowest bioaccessibility was determined in charcoal, representing black carbon (0.1 ± 0.1 % for ∑10 PAH-d) in contrast to higher bioaccessibility in peat (6.4 ± 2.2 %) and clay (4.8 ± 1.1 %). Highest bioaccessibility was determined in sand (26.9 ± 7.5 %). The results show a systematic impact of heterogeneous geosorbents on human oral bioaccessibility of PAH and particularly black carbon acting as a very strong geosorbent that reduces human health risk.
اظهر المزيد [+] اقل [-]Aerosol characteristics at a rural station in southern peninsular India during CAIPEEX-IGOC: physical and chemical properties النص الكامل
2015
Bisht, D. S. | Srivastava, A. K. | Pipal, A. S. | Srivastava, M. K. | Pandey, A. K. | Tiwari, S. | Pandithurai, G.
To understand the boundary layer characteristics and pathways of aerosol–cloud interaction, an Integrated Ground Observational Campaign, concurrent with Cloud Aerosol Interaction and Precipitation Enhancement Experiment, was conducted by the Indian Institute of Tropical Meteorology, Pune, under Ministry of Earth Sciences at Mahabubnagar (a rural environment, which is ~100 km away from an urban city Hyderabad in Andhra Pradesh), during the period of July–November 2011. Collected samples of PM₂.₅and PM₁₀were analyzed for water-soluble ionic species along with organic carbon (OC) and elemental carbon (EC). During study period, the average mass concentrations of PM₂.₅and PM₁₀were about 50(±10) and 69(±14) μg m⁻³, respectively, which are significantly higher than the prescribed Indian National Ambient Air Quality Standards values. The chemical species such as sum of anions and cations from measured chemical constituents were contributed to be 31.27 and 38.49 % in PM₂.₅and 6.35 and 5.65 % to the PM₁₀, whereas carbonaceous species contributed ~17.3 and 20.47 % for OC and ~3.0 and 3.10 % for EC, respectively. The average ratio of PM₂.₅/PM₁₀during study period was ~0.73(±0.2), indicating that the dominance of fine size particles. Carbonaceous analysis results showed that the average concentration of OC was 14 and 8.7 μg m⁻³, while EC was 2.1 and 1.5 μg m⁻³for PM₁₀and PM₂.₅, respectively. The ratios between OC and EC were estimated, which were 6.6 and 5.7 for PM₁₀and PM₂.₅, suggesting the presence of secondary organic aerosol. Total carbonaceous aerosol accounts 23 % of PM₁₀in which the contribution of OC is 20 % and EC is 3 %, while 20 % of PM₂.₅mass in which the contribution of OC is 17 % and EC is 3 %. Out of the total aerosols mass, water-soluble constituents contributed an average of 45 % in PM₁₀and 38 % in PM₂.₅including about 39 % anions and 6 % cations in PM₁₀, while 31 % anions and 7 % cations in PM₂.₅aerosol mass collectively at study site.
اظهر المزيد [+] اقل [-]Urban and rural habitats differ in number and type of bird feeders and in bird species consuming supplementary food النص الكامل
2015
Tryjanowski, Piotr | Skórka, Piotr | Sparks, Tim | Biaduń, Waldemar | Brauze, Tomasz | Hetmański, Tomasz | Martyka, Rafał | Indykiewicz, Piotr | Myczko, Łukasz | Kunysz, Przemysław | Kawa, Piotr | Czyż, Stanisław | Czechowski, Paweł | Polakowski, Michał | Zduniak, Piotr | Jerzak, Leszek | Janiszewski, Tomasz | Goławski, Artur | Duduś, Leszek | Nowakowski, Jacek J. | Wuczyński, Andrzej | Wysocki, Dariusz
Bird feeding is one of the most widespread direct interactions between man and nature, and this has important social and environmental consequences. However, this activity can differ between rural and urban habitats, due to inter alia habitat structure, human behaviour and the composition of wintering bird communities. We counted birds in 156 squares (0.25 km² each) in December 2012 and again in January 2013 in locations in and around 26 towns and cities across Poland (in each urban area, we surveyed 3 squares and also 3 squares in nearby rural areas). At each count, we noted the number of bird feeders, the number of bird feeders with food, the type of feeders, additional food supplies potentially available for birds (bread offered by people, bins) and finally the birds themselves. In winter, urban and rural areas differ in the availability of food offered intentionally and unintentionally to birds by humans. Both types of food availability are higher in urban areas. Our findings suggest that different types of bird feeder support only those species specialized for that particular food type and this relationship is similar in urban and rural areas.
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