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Resultados 3561-3570 de 4,043
Spatiotemporal patterns and potential sources of polychlorinated biphenyl (PCB) contamination in Scots pine (Pinus sylvestris) needles from Europe Texto completo
2016
Holt, Eva | Kočan, Anton | Klánová, Jana | Assefa, Anteneh | Wiberg, Karin
Using pine needles as a bio-sampler of atmospheric contamination is a relatively cheap and easy method, particularly for remote sites. Therefore, pine needles have been used to monitor a range of semi-volatile contaminants in the air. In the present study, pine needles were used to monitor polychlorinated biphenyls (PCBs) in the air at sites with different land use types in Sweden (SW), Czech Republic (CZ), and Slovakia (SK). Spatiotemporal patterns in levels and congener profiles were investigated. Multivariate analysis was used to aid source identification. A comparison was also made between the profile of indicator PCBs (ind-PCBs—PCBs 28, 52, 101, 138, 153, and 180) in pine needles and those in active and passive air samplers. Concentrations in pine needles were 220–5100 ng kg⁻¹ (∑₁₈PCBs − ind-PCBs and dioxin-like PCBs (dl-PCBs)) and 0.045–1.7 ng toxic equivalent (TEQ) kg⁻¹ (dry weight (dw)). Thermal sources (e.g., waste incineration) were identified as important sources of PCBs in pine needles. Comparison of profiles in pine needles to active and passive air samplers showed a lesser contribution of lower molecular weight PCBs 28 and 52, as well as a greater contribution of higher molecular weight PCBs (e.g., 180) in pine needles. The dissimilarities in congener profiles were attributed to faster degradation of lower chlorinated congeners from the leaf surface or metabolism by the plant.
Mostrar más [+] Menos [-]In search for a compromise between biodiversity conservation and human health protection in restoration of fly ash deposits: effect of anti-dust treatments on five groups of arthropods Texto completo
2016
Tropek, Robert | Cerna, Ilona | Straka, Jakub | Kočárek, Petr | Malenovsky, Igor | Tichanek, Filip | Sebek, Pavel
Recently, fly ash deposits have been revealed as a secondary refuge of critically endangered arthropods specialised on aeolian sands in Central Europe. Simultaneously, these anthropogenic habitats are well known for their negative impact on human health and the surrounding environment. The overwhelming majority of these risks are caused by wind erosion, the substantial decreasing of which is thus necessary. But, any effects of anti-dust treatments on endangered arthropods have never been studied. We surveyed communities of five arthropod groups (wild bees and wasps, leafhoppers, spiders, hoverflies and orthopteroid insects) colonising three fly ash deposits in the western Czech Republic. We focused on two different anti-dust treatments (~70 and 100 % cover of fly ash by barren soil) and their comparison with a control of bare fly ash. Altogether, we recorded 495 species, including 132 nationally threatened species (eight of them were considered to be extinct in the country) and/or 30 species strictly specialised to drift sands. Bees and wasps and leafhoppers contained the overwhelming majority of species of the highest conservation interest; a few other important records were also in spiders and orthopteroids. Total soil cover depleted the unique environment of fly ash and thus destroyed the high conservation potential of the deposits. On the other hand, partial coverage (with ~30 % of bare fly ash) still offered habitats for many of the most threatened species, as we showed by both regression and multivariate analyses, with a decrease of wind erosion. This topic still needs much more research interest, but we consider mosaic-like preservation of smaller spots of fly ash as one of the possible compromises between biodiversity and human health.
Mostrar más [+] Menos [-]Low birth weight of Vietnamese infants is related to their mother’s dioxin and glucocorticoid levels Texto completo
2016
Van Tung, Dao | Kido, Teruhiko | Honma, Seijiro | Manh, Ho Dung | Nhu, Dang Duc | Okamoto, Rie | Maruzeni, Shoko | Nishijo, Muneko | Nakagawa, Hideaki | Ngoc, Pham Thien | Van Toan, Ngo | Hung, Nguyen Ngoc | Minh, Nguyen Hung | Lê, Kế Sơn
We aimed to determine the relationship between dioxin congeners in maternal breast milk and maternal glucocorticoid levels with newborn birth weight after nearly 45 years of use of herbicides in the Vietnam War. The study subjects comprised 58 mother–infant pairs in a region with high dioxin levels in the soil (hotspot) and 62 pairs from a control region. Dioxin levels in maternal breast milk were measured by HRGC-HRMS. Salivary glucocorticoid levels were determined by LC-MS/MS. Dioxin congener levels in mothers from the hotspot were found to be two to fivefold higher than those in mothers from the control region. Birth weight was inversely correlated with 2,3,7,8-TeCDD and 2,3,4,7,8-PeCDF congener levels. The rate of newborns whose birth weight was less than 2500 g was threefold higher in the hotspot (12 %) than in the control region (4 %). Salivary glucocorticoid levels in mothers with low birth weight infants were significantly higher than those in the normal birth weight group. Low birth weight of Vietnamese newborns in a hotspot for dioxin levels is related to some dioxin congener levels and high glucocorticoid levels in mothers. This finding in mother–infant pairs suggests that excess maternal glucocorticoid levels are related to dioxin burden and they result in low birth weight.
Mostrar más [+] Menos [-]Trends and variations of pH and hardness in a typical semi-arid river in a monsoon climate region during 1985–2009 Texto completo
2016
Hao, Shaonan | Li, Xuyong | Jiang, Yan | Zhao, Hongtao | Yang, Lei
The rapid growth of urbanization and industrialization, along with dramatic climate change, has strongly influenced hydrochemical characteristics in recent decades in China and thus could cause the variation of pH and general total hardness of a river. To explore such variations and their potential influencing factors in a river of the monsoon climate region, we analyzed a long-term monitoring dataset of pH, SO₄ ²⁻, NOₓ, general total hardness (GH), Mg²⁺, Ca²⁺, and Cl⁻ in surface water and groundwater in the Luan River basin from 1985 to 2009. The nonparametric Seasonal Kendall trend test was used to test the long-term trends of pH and GH. Relationship between the affecting factors, pH and GH were discussed. Results showed that pH showed a decreasing trend and that GH had an increasing trend in the long-term. Seasonal variation of pH and GH was mainly due to the typical monsoon climate. Results of correlation analysis showed that the unit area usage amounts of chemical fertilizer, NO₃ ⁻, and SO₄ ²⁻ were negatively correlated with pH in groundwater. In addition, mining activity affected GH spatial variation. Acid deposition, drought, and increasing the use of chemical fertilizers would contribute to the acidification trend, and mining activities would affect the spatial variation of GH. Variations of precipitation and runoff in semi-arid monsoon climate areas had significant influences on the pH and GH. Our findings implied that human activities played a critical role in river acidification in the semi-arid monsoon climate region of northern China.
Mostrar más [+] Menos [-]Enantioselective metabolism and toxic effects of metalaxyl on primary hepatocytes from rat Texto completo
2016
Wang, Xinru | Zhu, Wentao | Qiu, Jing | Zhang, Ping | Wang, Yao | Zhou, Zhiqiang
Enantiomers of chiral compounds often exhibit enantioselective adverse effects and biochemical processes in non-target organisms. In this study, enantioselective metabolism and toxic effects of metalaxyl enantiomers on primary rat hepatocytes were investigated. Stereoselectivity was observed on both degradation of metalaxyl and formation of metabolites. (−)-R-metalaxyl eliminated faster than (+)-S-metalaxyl, while the hydroxylmetalaxyl, demethylmetalaxyl, and didemethylmetalaxyl metabolites derived from 50-μM (+)-S-metalaxyl after 24 h of incubation were approximately 1.57, 1.43, and 1.86 times more than that of (−)-R-metalaxyl, respectively. According to the methyl tetrazolium (MTT) assay, the EC₅₀ values (24 h) for rac-, (+)-S-, and (−)-R-metalaxyl were 1788.22, 2066.73, and 2263.71 μM, respectively. An accordant enantioselective effect on oxidative stress suggested that the enantioselective cytotoxicity induced by metalaxyl enantiomers may partly contribute to enantioselective oxidative damage and mitochondrial dysfunction. Such results could be of great importance for credible environmental and toxicological risk assessment of metalaxyl.
Mostrar más [+] Menos [-]Thermal co-reduction approach to vary size of silver nanoparticle: its microbial and cellular toxicology Texto completo
2016
Das Gupta, Nandita | Ranjan, Shivendu | Rajendran, Bhavapriya | Manickam, Venkatraman | Ramalingam, Chidambaram | Avadhani, Ganesh S. | Kumar, Ashutosh
In recent years, silver nanoparticles (AgNPs) have attracted considerable interest in the field of food, agriculture and pharmaceuticals mainly due to its antibacterial activity. AgNPs have also been reported to possess toxic behavior. The toxicological behavior of nanomaterials largely depends on its size and shape which ultimately depend on synthetic protocol. A systematic and detailed analysis for size variation of AgNP by thermal co-reduction approach and its efficacy toward microbial and cellular toxicological behavior is presented here. With the focus to explore the size-dependent toxicological variation, two different-sized NPs have been synthesized, i.e., 60 nm (Ag60) and 85 nm (Ag85). A detailed microbial toxicological evaluation has been performed by analyzing minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), diameter of inhibition zone (DIZ), growth kinetics (GrK), and death kinetics (DeK). Comparative cytotoxicological behavior was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It has been concluded by this study that the size of AgNPs can be varied, by varying the concentration of reactants and temperature called as “thermal co-reduction” approach, which is one of the suitable approaches to meet the same. Also, the smaller AgNP has shown more microbial and cellular toxicity.
Mostrar más [+] Menos [-]Development of a magnetic coagulant based on Moringa oleifera seed extract for water treatment Texto completo
2016
Santos, Tássia R. T. | Silva, Marcela F. | Nishi, Leticia | Vieira, Angélica M. S. | Klein, Márcia R. F. | Andrade, Murilo B. | Vieira, Marcelo F. | Bergamasco, Rosângela
In this work, to evaluate the effectiveness of the coagulation/flocculation using a natural coagulant, using Moringa oleifera Lam functionalized with magnetic iron oxide nanoparticles, producing flakes that are attracted by an external magnetic field, thereby allowing a fast settling and separation of the clarified liquid, is proposed. The removal efficiency of the parameters, apparent color, turbidity, and compounds with UV₂₅₄ₙₘ absorption, was evaluated. The magnetic functionalized M. oleifera Lam coagulant could effectively remove 90 % of turbidity, 85 % of apparent color, and 50 % for the compounds with absorption at UV₂₅₄ₙₘ, in surface waters under the influence of an external magnetic field within 30 min. It was found that the coagulation/flocculation treatment using magnetic functionalized M. oleifera Lam coagulant was able to reduce the values of the physico-chemical parameters evaluated with reduced settling time.
Mostrar más [+] Menos [-]Constructed wetlands may lower inorganic nutrient inputs but enhance DOC loadings into a drinking water reservoir in North Wales Texto completo
2016
Scholz, C. | Jones, T. G. | West, M. | Ehbair, A. M. S. | Dunn, C. | Freeman, C.
The objective of this study was to monitor a newly constructed wetland (CW) in north Wales, UK, to assess whether it contributes to an improvement in water quality (nutrient removal) of a nearby drinking water reservoir. Inflow and outflow of the Free Water Surface (FWS) CW were monitored on a weekly basis and over a period of 6 months. Physicochemical parameters including pH, conductivity and dissolved oxygen (DO) were measured, as well as nutrients and dissolved organic and inorganic carbon (DOC, DIC) concentration. The CW was seen to contribute to water quality improvement; results show that nutrient removal took place within weeks after construction. It was found that 72 % of initial nitrate (N0₃ ⁻), 53 % of initial phosphate (PO₄ ³⁻) and 35 % of initial biological oxygen demand (BOD) were removed, calculated as a total over the whole sampling period. From our study, it can be concluded that while inorganic nutrients do decline in CWs, the DOC outputs increases. This may suggest that CWs represent a source for DOC. To assess the carbon in- and output a C budget was calculated.
Mostrar más [+] Menos [-]Investigating the removal of some pharmaceutical compounds in hospital wastewater treatment plants operating in Saudi Arabia Texto completo
2016
Al Qarni, Hamed | Collier, Philip | O’Keeffe, Juliette | Akunna, Joseph
The concentrations of 12 pharmaceutical compounds (atenolol, erythromycin, cyclophosphamide, paracetamol, bezafibrate, carbamazepine, ciprofloxacin, caffeine, clarithromycin, lidocaine, sulfamethoxazole and N-acetylsulfamethoxazol (NACS)) were investigated in the influents and effluents of two hospital wastewater treatment plants (HWWTPs) in Saudi Arabia. The majority of the target analytes were detected in the influent samples apart from bezafibrate, cyclophosphamide, and erythromycin. Caffeine and paracetamol were detected in the influent at particularly high concentrations up to 75 and 12 ug/L, respectively. High removal efficiencies of the pharmaceutical compounds were observed in both HWWTPs, with greater than 90 % removal on average. Paracetamol, sulfamethoxazole, NACS, ciprofloxacin, and caffeine were eliminated by between >95 and >99 % on average. Atenolol, carbamazepine, and clarithromycin were eliminated by >86 % on average. Of particular interest were the high removal efficiencies of carbamazepine and antibiotics that were achieved by the HWWTPs; these compounds have been reported to be relatively recalcitrant to biological treatment and are generally only partially removed. Elevated temperatures and high levels of sunlight were considered to be the main factors that enhanced the removal of these compounds.
Mostrar más [+] Menos [-]Characterization of phosphorus forms in lake macrophytes and algae by solution 31P nuclear magnetic resonance spectroscopy Texto completo
2016
Feng, Weiying | Zhu, Yuanrong | Wu, Fengchang | Meng, Wei | Giesy, John P. | He, Zhongqi | Song, Lirong | Fan, Mingle
Debris from aquatic macrophytes and algae are important recycling sources of phosphorus (P), which can result in continuing blooms of algae by recycling bioavailable P in the eutrophic lakes. However, knowledge of forms of P in aquatic macrophytes and algae and their contribution to internal loads of P in lakes is limited. Without such knowledge, it is difficult to develop appropriate strategies to remediate and or restore aquatic ecosystems that have become eutrophic. Therefore, in this work, P was extracted from six types of aquatic macrophytes and algae collected from Tai Lake of China and characterized by use of solution ³¹P-nuclear magnetic resonance (NMR) spectroscopy. When extracted by 0.5 M NaOH-25 mM EDTA, extraction recovery of total P(TP) and organic P(Pₒ) exceeded 90 %. Concentrations of Pₒ in algae and aquatic macrophytes were 5552 mg kg⁻¹ and 1005 mg kg⁻¹ and accounted for 56.0 and 47.2 % of TP, respectively. When Pₒ, including condensed P, was characterized by solution ³¹P-NMR Pₒ in algae included orthophosphate monoesters (79.8 %), pyrophosphate (18.2 %), and orthophosphate diester (2.0 %), and Pₒ in aquatic macrophytes included orthophosphate monoesters (90.3 %), pyrophosphate (4.2 %), and orthophosphate diester (5.5 %). Additionally, orthophosphate monoesters in algal debris mainly included β-glycerophosphate (44.1 %), α-glycerophosphate (13.5 %), and glucose 6-phosphate (13.5 %). Orthophosphate monoesters in aquatic macrophytes mainly included β-glycerophosphate (27.9 %), α-glycerophosphate (24.6 %), and adenosine 5′ monophosphate (8.2 %). Results derived from this study will be useful in better understanding nutrient cycling, relevant eutrophication processes, and pollution control for freshwater lakes.
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