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Sorption of apolar and polar organic contaminants by waste tire rubber and its chars in single- and bi-solute systems Full text
2011
Lian, Fei | Huang, Fang | Chen, Wei | Xing, Baoshan | Zhu, Lingyan
Single- and bi-solute sorption of organic compounds [1,3-dichlorbenzene (DCB), 1,3-dinitrobenzene (DNB) and 2,4-dichlorophenol (DCP)] on ground tire rubber and its chars was studied. The chars were prepared by pyrolyzing tire rubber at different temperatures (200–800 °C). Their surface area, aromaticity and hydrophobicity increase greatly with pyrolytic temperature, and the polymeric phase is partly converted into a condensed phase. The sorption of DNB and DCP increases with pyrolytic temperature and is characterized by a transition from a partition dominant to an adsorption dominant process. However, the sorption of DCB linearly decreases with the pyrolytic temperature. The enhanced adsorption of DNB and DCP on carbonized phase is primarily attributed to nonhydrophobic interactions such as π–π electron-donor–acceptor interactions and/or H bonding. The higher partition of DCB to polymeric phase is attributed to its high hydrophobicity. Competitive sorption between DCB and DCP on the tire chars is highly dependent on dissociation of the latter.
Show more [+] Less [-]Reduced ozone by air filtration consistently improved grain yield in wheat Full text
2011
This study considered effects of reduced [O₃] on wheat yield. Open-top chamber charcoal filtered air treatments were compared with non-filtered treatments for field-grown wheat. 30 experiments meeting requirements were found, representing nine countries in North America, Europe and Asia. 26 experiments reported improved yield and 4 experiments reduced yield by filtration, a significant positive effect. Average yield improvement was 9%. Average daytime [O₃] was reduced by filtration from 35 to 13 nmol mol⁻¹. Filtration efficiency was 63% for O₃ and 56% for SO₂. For NOₓ it was observed that NO₂ was reduced and NO increased by filtration. Thus, filters convert NO₂ to NO. Most experiments reported low or very low [SO₂] and [NOₓ]. Thus, O₃ can be concluded to be the main phytotoxic component in the experiments. Elevated [NO₂] was observed in one experiment. The conclusion is that current [O₃] over large parts of the world adversely affect wheat yield.
Show more [+] Less [-]The removal of microorganisms and organic micropollutants from wastewater during infiltration to aquifers after irrigation of farmland in the Tula Valley, Mexico Full text
2011
Chávez, Alma | Maya, Catalina | Gibson, Richard | Jiménez, Blanca
The Tula Valley receives untreated wastewater from Mexico City for agricultural irrigation, half of which infiltrates to aquifers from where drinking water is extracted. Samples of wastewater and infiltrated water from three areas of the valley were analyzed for microorganisms, organic micropollutants, and some basic parameters. Concentrations of microorganisms in the infiltrated water were generally very low but the incidence of fecal coliforms (present in 68% of samples), somatic bacteriophages (36%), Giardia spp. (14%), and helminth eggs (8%) suggested a health risk. Organic micropollutants, often present at high concentrations in the wastewater, were generally absent from the infiltrated water except carbamazepine which was in 55% of samples (up to 193 ng/L). There was no correlation between carbamazepine concentrations and the presence of microorganisms but highest concentrations of carbamazepine and boron coincided. A treatment such as nanofiltration would be necessary for the infiltrated water to be a safe potable supply.
Show more [+] Less [-]Spatial and seasonal variations of polycyclic aromatic hydrocarbons in Haihe Plain, China Full text
2011
Wang, Rong | Cao, Hongying | Li, Wei | Wang, Wei | Wang, Wentao | Zhang, Liwen | Liu, Jiumeng | Ouyang, Huiling | Tao, Shu
A dynamic fugacity model was developed to simulate the spatial and seasonal variations of PAHs in Haihe Plain, China. The calculated and measured concentrations exhibited good consistency in magnitude with deviations within a factor of 4 in air and 2 in soil. The spatial distributions of PAHs in air were mainly controlled by emission while the seasonal variations were dominated by emission and gas–particle partition. In soil, the spatial distributions of PAHs were controlled by the soil organic carbon content while the seasonal variations were insignificant. The severest soil contamination was observed in Shanxi and followed by the southwest of Hebei province. Transfer fluxes of total PAHs between air and soil were calculated. The spatial distribution of air-to-soil flux was closely related to the landcover while the soil-to-air flux changed with soil organic matter content. Monte Carlo simulation was done to evaluate the uncertainty of the estimated results in air.
Show more [+] Less [-]Application of air pollution dispersion modeling for source-contribution assessment and model performance evaluation at integrated industrial estate-Pantnagar Full text
2011
Banerjee, T. | Barman, S.C. | Srivastava, R.K.
Source-contribution assessment of ambient NO₂ concentration was performed at Pantnagar, India through simulation of two urban mathematical dispersive models namely Gaussian Finite Line Source Model (GFLSM) and Industrial Source Complex Model (ISCST-3) and model performances were evaluated. Principal approaches were development of comprehensive emission inventory, monitoring of traffic density and regional air quality and conclusively simulation of urban dispersive models. Initially, 18 industries were found responsible for emission of 39.11 kg/h of NO₂ through 43 elevated stacks. Further, vehicular emission potential in terms of NO₂ was computed as 7.1 kg/h. Air quality monitoring delineates an annual average NO₂ concentration of 32.6 μg/m³. Finally, GFLSM and ISCST-3 were simulated in conjunction with developed emission inventories and existing meteorological conditions. Models simulation indicated that contribution of NO₂ from industrial and vehicular source was in a range of 45–70% and 9–39%, respectively. Further, statistical analysis revealed satisfactory model performance with an aggregate accuracy of 61.9%.
Show more [+] Less [-]Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L Full text
2011
Qu, Jiao | Yuan, Xing | Wang, Xinhong | Shao, Peng
A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000mgkg⁻¹ in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235–10,980mgkg⁻¹) and accumulated biomass (with a mean dry weight of 25.7gplant⁻¹) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources.
Show more [+] Less [-]Polychlorinated naphthalenes (PCNs) in riverine and marine sediments of the Laizhou Bay area, North China Full text
2011
Pan, Xiaohui | Tang, Jianhui | Chen, Yingjun | Li, Jun | Zhang, Gan
PCN congeners were analyzed in marine and riverine sediments of the Laizhou Bay area, North China. Concentrations of PCNs ranged from 0.12 to 5.1 ng g⁻ ¹ dry weight (dw) with a mean value of 1.1 ng g⁻ ¹ dw. The levels of PCNs varied largely, with industrial group approximately ten folds higher than those of the rural in riverine sediment. A strong impact by direct discharge from local factories was suggested. Similar compositional profiles were found within groups. High resemblance of compositional profiles between industrial samples and Halowax 1014 was observed. It was indicated that PCNs in riverine sediments were mainly from release of industrial usage, with additional contributions from industrial thermal process at certain sites. In marine sediments, it was suggested that PCNs along the coast of Laizhou Bay were mainly controlled by riverine input. While in the central bay, PCN distributions were possibly impacted by combined multiple factors.
Show more [+] Less [-]New insights into the sorption mechanism of cadmium on red mud Full text
2011
Luo, Lei | Ma, Chenyan | Ma, Yibing | Zhang, Shuzhen | Lv, Jitao | Cui, Mingqi
Effectiveness and mechanism of cadmium (Cd) sorption on original, acidified and ball milling nano-particle red muds were investigated using batch sorption experiments, sequential extraction analysis and X-ray absorption near edge structure (XANES) spectroscopy. The maximum sorption capacity of Cd was 0.16, 0.19, and 0.21mol/kg for the original, acidified, and nano-particle red muds at pH 6.5, respectively. Both acidification and ball-milling treatments significantly enhanced Cd sorption and facilitated transformation of Cd into less extractable fractions. The Cd LIII-edge XANES analysis indicated the formation of inner-sphere complexes of Cd similar to XCdOH (X represents surface groups on red mud) on the red mud surfaces although outer-sphere complexes of Cd were the primary species. This work shed light on the potential application of red mud to remediate Cd-contaminated soils and illustrated the promising tool of XANES spectroscopy for speciation of multicomponent systems of environmental relevance.
Show more [+] Less [-]Potential mechanisms of phthalate ester embryotoxicity in the abalone Haliotis diversicolor supertexta Full text
2011
Zhou, Jin | Cai, Zhong-Hua | Xing, Ke-Zhi
The effects and associated toxicological mechanisms of five phthalate esters (PAEs) on abalone embryonic development were investigated by exposing the embryos to a range of PAEs concentrations (0.05, 0.2, 2 and 10μg/mL). The results showed that PAEs could significantly reduce embryo hatchability, increase developmental malformations, and suppress the metamorphosis of abalone larvae. The possible toxicological mechanisms of PAEs to abalone embryos included, affecting the Na⁺–K⁺-pump and Ca²⁺–Mg²⁺-pump activities, altering the peroxidase (POD) level and the malondialdehyde (MDA) production, damaging the extraembryonic membranes structure, as well as disrupting endocrine-related genes (gpx, cyp3a, and 17β-hsd 12) expression properties. Taken together, this work showed that PAEs adversely affected the embryonic ontogeny of abalone. The abilities of PAEs affecting the osmoregulation, inducing oxidative stress, damaging embryo envelope structure, and causing physiological homeostasis disorder, are likely to be a part of the common mechanisms responsible for their embryonic toxicity.
Show more [+] Less [-]The fate of the aqueous phase polycyclic aromatic hydrocarbon fraction in a detention pond system Full text
2011
The concentration of dissolved polycyclic aromatic hydrocarbons (PAH) in influent, effluent, and within a detention pond system was measured. The "soluble fraction" was operationally defined as the PAHs in solution that passed through a 1.2 μm filter. The results show that influent and effluent PAH concentrations were similar, indicating that dissolved PAH moved essentially unhindered through the detention pond system. In general, low molecular weight PAH were present at the highest concentrations and the highest PAH concentrations were measured in Summer. Also, year-to-year variations in PAH concentration were observed. At the end of sufficiently large storms, the pond was comparably unpolluted. During dry periods, the dissolved PAH concentration rose, possibly due to evapoconcentration and by partitioning of PAH from trapped contaminated sediment in the detention pond system. This study provides evidence that aqueous-phase PAH concentrations in runoff water were relatively unaffected by the passage through a conventional detention pond system.
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