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Treatment of industrial effluents in constructed wetlands: Challenges, operational strategies and overall performance Full text
2015
The application of constructed wetlands (CWs) has significantly expanded to treatment of various industrial effluents, but knowledge in this field is still insufficiently summarized. This review is accordingly necessary to better understand this state-of-the-art technology for further design development and new ideas. Full-scale cases of CWs for treating various industrial effluents are summarized, and challenges including high organic loading, salinity, extreme pH, and low biodegradability and color are evaluated. Even horizontal flow CWs are widely used because of their passive operation, tolerance to high organic loading, and decolorization capacity, free water surface flow CWs are effective for treating oil field/refinery and milking parlor/cheese making wastewater for settlement of total suspended solids, oil, and grease. Proper pretreatment, inflow dilutions through re-circulated effluent, pH adjustment, plant selection and intensifications in the wetland bed, such as aeration and bioaugmentation, are recommended according to the specific characteristics of industrial effluents.
Show more [+] Less [-]Air pollution and mortality: Effect modification by personal characteristics and specific cause of death in a case-only study Full text
2015
Qiu, Hong | Tian, Linwei | Ho, Kin-fai | Pun, Vivian C. | Wang, Xiaorong | Yu, Ignatius T.S.
Short-term effects of air pollution on mortality have been well documented in the literature worldwide. Less is known about which subpopulations are more vulnerable to air pollution. We conducted a case-only study in Hong Kong to examine the potential effect modification by personal characteristics and specific causes of death. Individual information of 402,184 deaths of non-external causes and daily mean concentrations of air pollution were collected from 2001 to 2011. For a 10 μg/m3 increase of pollution concentration, people aged ≥∇65 years (compared with younger ages) had a 0.9–1.8% additional increase in mortality related to PM, NO2, and SO2. People dying from cardiorespiratory diseases (compared with other non-external causes) had a 1.6–2.3% additional increase in PM and NO2 related mortality. Other subgroups that were particularly susceptible were females and those economically inactive. Lower socioeconomic status and causes of cardiorespiratory diseases would increase the likelihood of death associated with air pollution.
Show more [+] Less [-]Modeling TiO2 nanoparticle phototoxicity: The importance of chemical concentration, ultraviolet radiation intensity, and time Full text
2015
Li, Shibin | Erickson, Russell J. | Wallis, Lindsay K. | Diamond, Steve (Stephen A.) | Hoff, Dale J.
As a semiconductor with wide band gap energy, TiO2 nanoparticles (nano-TiO2) are highly photoactive, and recent efforts have demonstrated phototoxicity of nano-TiO2 to aquatic organisms. However, a dosimetry model for the phototoxicity of nanomaterials that incorporates both direct UV and photo-activated chemical toxicity has not yet been developed. In this study, a set of Hyalella azteca acute toxicity bioassays at multiple light intensities and nano-TiO2 concentrations, and with multiple diel light cycles, was conducted to assess how existing phototoxicity models should be adapted to nano-TiO2. These efforts demonstrated (a) adherence to the Bunsen-Roscoe law for the reciprocity of light intensity and time, (b) no evidence of damage repair during dark periods, (c) a lack of proportionality of effects to environmental nano-TiO2 concentrations, and (d) a need to consider the joint effects of nano-TiO2 phototoxicity and direct UV toxicity.
Show more [+] Less [-]Sex specific response in cholesterol level in zebrafish (Danio rerio) after long-term exposure of difenoconazole Full text
2015
Mu, Xiyan | Wang, Kai | Chai, Tingting | Zhu, Lizhen | Yang, Yang | Zhang, Jie | Pang, Sen | Wang, Chengju | Li, Xuefeng
Difenoconazole is a widely used triazole fungicide, its extensive application may potentially cause toxic effects on non-target organisms. To investigate the effect of difenoconazole on cholesterol content and related mechanism, adult zebrafish were exposed to environmental related dosage (0.1, 10 and 500 μg/L) difenoconazole. The body weight and hepatic total cholesterol (TCHO) level was tested at 7, 15 and 30 days post exposure (dpe). The expressions of eight cholesterol synthesis genes and one cholesterol metabolism gene were assessed via Quantitative PCR method. The significant decrease of TCHO level in male zebrafish liver was observed at 15 and 30 dpe, which was accompanied by apparent hepatic cholesterol-genesis genes expression decline. In comparison with males, female zebrafish showed different transcription modification of tested genes, and the cholesterol content maintain normal level during the whole exposure.
Show more [+] Less [-]Interactions of multiwalled carbon nanotubes with algal cells: Quantification of association, visualization of uptake, and measurement of alterations in the composition of cells Full text
2015
Rhiem, Stefan | Riding, Matthew J. | Baumgartner, Werner | Martin, Francis L. | Semple, K. T. (Kirk T.) | Jones, K. C. (Kevin C.) | Schäffer, Andreas | Maes, Hanna M.
Carbon nanotubes (CNTs) are considered promising materials in nanotechnology. We quantified CNT accumulation by the alga Desmodesmus subspicatus. Cells were exposed to radiolabeled CNTs (14C-CNTs; 1 mg/L) to determine uptake and association, as well as elimination and dissociation in clear media. Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) was used to detect effects of CNTs on algae. CNT-cell interactions were visualized by electron microscopy and related to alterations in their cell composition. A concentration factor of 5000 L/kg dry weight was calculated. Most of the material agglomerated around the cells, but single tubes were detected in the cytoplasm. Computational analyses of the ATR-FTIR data showed that CNT treated algae differed from controls at all sampling times. CNT exposure changed the biochemical composition of cells. The fact that CNTs are bioavailable for algae and that they influence the cell composition is important with regard to environmental risk assessment of this nanomaterial.
Show more [+] Less [-]Short-term exposure to fine and coarse particles and mortality: A multicity time-series study in East Asia Full text
2015
Few studies on size-specific health effects of particulate matter have been conducted in Asia. We examined the association between both fine and coarse particles (PM2.5 and PM10−2.5) and mortality across 11 East Asian cities from 4 countries (Korea, Japan, Taiwan, and China). We performed a two-stage analysis: we generated city-specific estimates using a time-series analysis with a generalized additive model (Quasi-Poisson distribution), and estimated the overall effects by conducting a meta-analysis. Each 10−μg/m3 increase in PM2.5 (lag01) was associated with an increase of 0.38% (95% confidence interval = 0.21%–0.55%) in all causes mortality, 0.96% (0.46%–1.46%) in cardiovascular mortality, and 1% (0.23%–1.78%) in respiratory mortality. Each 10−μg/m3 increase in PM10−2.5 (lag01) was associated with cardiovascular mortality (0.69%, [0.05%–1.33%]), although this association attenuated after controlling for other pollutants, especially PM2.5. Increased mortality was associated with increasing PM2.5 and PM10−2.5 concentrations over 11 East Asian cities.
Show more [+] Less [-]Trends of deposition fluxes and loadings of sulfur dioxide and nitrogen oxides in the artificial Three Northern Regions Shelter Forest across northern China Full text
2015
Zhang, Xiaodong | Huang, Tao | Zhang, Leiming | Gao, Hong | Shen, Yanjie | Ma, Jianmin
This study provides the first estimate of dry deposition fluxes of criteria air pollutants (SO2 and NOx) across the Three Northern Regions Shelter Forest (TNRSF) region in Northern China and their long-term trends from 1982 to 2010 using the inferential method. Dry deposition velocities of SO2 and NOx increased in many places of the TNRSF up to 118.2% for SO2 and 112.1% for NOx over the last three decades due to the increased vegetation coverage over the TNRSF. The highest atmospheric deposition fluxes of SO2 and NOx were found in the Central-North China region, followed by the Northeast and the Northwest China regions of the TNRSF. A total of 820,000 t SO2 and 218,000 t NOx was estimated to be removed from the atmosphere through dry deposition process over the TNRSF from 1982 to 2010. About 50% of the total removal occurred in the Central-North China region. The estimated total SO2 and NOx dry deposition fluxes from 1982 to 2010 between a TNRSF site in this region and an adjacent farmland outside the TNRSF showed that the fluxes of these two chemicals at the TNRSF site were the factors of 2–3 greater than their fluxes in the farmland.
Show more [+] Less [-]Organochlorine pesticides and polychlorinated biphenyls in air, grass and yak butter from Namco in the central Tibetan Plateau Full text
2015
Wang, Chuanfei | Wang, Xiaoping | Yuan, Xiaohua | Ren, Jiao | Gong, Ping
Limited studies on bioaccumulation of persistent organic pollutants (POPs) along terrestrial food chains were conducted. The food chain air–grass–yak (butter) in the pasture region of Namco in the central Tibetan Plateau (TP) was chosen for study. The air, grass and butter POPs in the TP were at the lower end of the concentrations generally found around the globe. HCB was the main pollutant in air and butter. Besides HCB, β-HCH and p,p′-DDE were the other major compounds in butter. Along the food chain, DDTs and high molecular weight PCB-138, 153 and 180 had higher Biological Concentration Factor values. The air–butter transfer factors of POPs were derived and demonstrated the practical advantage in predicting the atmospheric OCPs and PCBs to the TP. This study sheds light on the transfer and accumulation of POPs along the terrestrial food chain of the TP.
Show more [+] Less [-]Temporal changes (1997–2012) of perfluoroalkyl acids and selected precursors (including isomers) in Swedish human serum Full text
2015
Gebbink, Wouter A. | Glynn, Anders | Berger, Urs
Concentrations (including isomer patterns) and temporal changes (1997–2012) of perfluoroalkyl acids (PFAAs) and selected perfluorooctane sulfonate (PFOS) and perfluoroalkyl carboxylic acid (PFCA) precursors were determined in serum samples from Swedish women. Perfluorooctane sulfonamide (FOSA) and perfluorooctane sulfonamidoacetic acid (FOSAA), as well as its N-methyl and N-ethyl derivatives (MeFOSAA and EtFOSAA) were consistently detected. Highest PFOS precursor concentrations were found for EtFOSAA (before year 2000) or MeFOSAA and FOSAA (after 2000). Disappearance half-lives for all PFOS precursors were shorter compared to PFOS. 4:2/6:2 and 6:2/6:2 polyfluoroalkyl phosphate diesters (diPAPs) were detected in <60% of the samples, whereas 6:2/8:2 and 8:2/8:2 diPAPs were detected in >60% of the samples, but showed no significant change in concentrations over time. Linear and sum-branched isomers were quantified separately for three PFAAs and three precursors. Significant changes between 1997 and 2012 in the % linear isomer were observed for PFOA and FOSA (increase) and PFOS (decrease).
Show more [+] Less [-]The characteristic of Pb isotopic compositions in different chemical fractions in sediments from Three Gorges Reservoir, China Full text
2015
Han, Lanfang | Gao, Bo | Wei, Xin | Gao, Li | Xu, Dongyu | Sun, Ke
To explore the distribution and sources of Pb within the Three Gorges Reservoir (TGR), Pb concentrations and isotope ratios were measured in sediment cores collected from one mainstream and three tributaries. The results showed that sediments contained an average of 43.54 mg kg−1 of Pb, roughly 1.6 times higher than the geochemical background concentration. Mainstream sediments showed higher average Pb concentrations but slightly less 206Pb/207Pb and more radiogenic 207Pb/208Pb ratios than all tributaries. Most Pb occurred in reducible phases, with much less in exchangeable and oxidizable fractions; thus, Fe–Mn oxides may be the major sink of anthropogenic Pb. Bi-plots of 206Pb/207Pb versus Pb content, and of 206Pb/207Pb versus 207Pb/208Pb, indicated that coal combustion was the predominant anthropogenic Pb source for exchangeable, reducible, and oxidizable fractions, while residual Pb mainly occurred naturally. The average percentage of coal consumption contribution was 61.1% for the Pb contamination in sediments in the lower reaches in the TGR region.
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