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841.
842.
843.
Edeltrauda Helios Rybicka Michael Jefferson Wilson 《Environmental science and pollution research international》2000,7(1):7-13
The examinations of selected wastes and stream sediments from the vicinity of a chemical plant by sequential extraction procedures
and direct methods, SEM/EDX and XRD, were carried out in order to identify the different forms of chromium, particularly as
they are released to potential mobility. The results show that the top and bottom waste samples contain 37,756 and 53,650
μg g1 Cr, respectively, but about 7% and 2% of the total chromium type Cr(VI). The chemical extraction results show that the mobility
of Cr in the upper part of the waste pile is significantly higher than in the bottom section; the exchangeable form of Cr
accounts for 25% and < 1%, respectively, the last one irrespective of redox conditions. About 50% of Cr is associated with
the reducible fraction of the top waste, and similar with the residual fraction in the bottom waste. Oxidation of the bottom
waste shift some portion of Cr from residual to the moderately reducible fraction. The major Cr-forms in the river sediments
are compounded with Fe-oxides. The < 2 μm size fraction of the selected sediment sample, particular enriched in chromium contained
up to 73,000 μg g1 Cr with about 95% of this in the moderately reducible fraction, predominantly bound with oxyhydroxides. SEM/EDX and XRD analysis
of wastes and river sediment indicate that the main insoluble Cr-phase is ferroan — (Mg, Fe) (Cr, Al)2O4 which would be dissolved mainly in the residual fraction. 相似文献
844.
845.
Jing Bai Huijun Yao Maosheng Lin Lina Zhang Fuan Lei Xiaofei Li Junsheng Guo 《Journal of environmental radioactivity》2010,101(11):969-973
The present paper reports the biosorption of uranium onto chemically modified yeast cells, Rhodotorula glutinis, in order to study the role played by various functional groups in the cell wall. Esterification of the carboxyl groups and methylation of the amino groups present in the cells were carried out by methanol and formaldehyde treatment, respectively. The uranium sorption capacity increased 31% for the methanol-treated biomass and 11% for the formaldehyde-treated biomass at an initial uranium concentration of 140 mg/L. The enhancement of uranium sorption capacity was investigated by Fourier transform infrared (FTIR) spectroscopy analysis, with amino and carboxyl groups were determined to be the important functional groups involved in uranium binding. The biosorption isotherms of uranium onto the raw and chemically modified biomass were also investigated with varying uranium concentrations. Langmuir and Freundlich models were well able to explain the sorption equilibrium data with satisfactory correlation coefficients higher than 0.9. 相似文献
846.
A lab-scale intermittently aerated sequencing batch reactor(IASBR)was applied to treat anaerobically digested swine wastewater(ADSW)to explore the removal characteristics of veterinary antibiotics.The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand(COD)volumetric loadings,solid retention times(SRT)and ratios of COD to total nitrogen(TN)or COD/TN.Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics.Mass balance analysis revealed that greater than 60%of antibiotics in the influent were biodegraded in the IASBR,whereas averagely 24%were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium.Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand(COD)volumetric loadings,which could achieve up to 85.1%±1.4%at 0.17±0.041 kg COD/m-3/day,while dropped to 75.9%±1.3%and 49.3%±12.1%when COD volumetric loading increased to 0.65±0.032 and1.07±0.073 kg COD/m-3/day,respectively.Tetracyclines,the dominant antibiotics in ADSW,were removed by 87.9%in total at the lowest COD loading,of which 30.4%were contributed by sludge sorption and 57.5%by biodegradation,respectively.In contrast,sulfonamides were removed about 96.2%,almost by biodegradation.Long SRT seemed to have little obvious impact on antibiotics removal,while a shorter SRT of 30–40 day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge.Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work. 相似文献
847.
Wenguang Li Xingang Liu Yuanhang Zhang Kang Sun Yusheng Wu Rui Xue Limin Zeng Yu Qu Junling An 《环境科学学报(英文版)》2018,30(1):236-249
To investigate the characteristics and the specific mechanism of continuous haze,comprehensive measurements were conducted from 15 October to 19 November in the Atmospheric Environment Monitoring Super-Station in Heshan of Guangdong province.Five haze episodes occurred in October and November 2014 in the Pearl River Delta(PRD)region. The meteorological parameters, gas data, chemical compositions, and optical parameters of the aerosols were obtained. Among these events, the second haze episode,with the highest concentration of PM2.5 of 187.51 μg/m~3, was the most severe. NO~3-was always higher than SO_4~(2-), which indicated that motor vehicles played an important role in the haze, even though the oxidation rate from SO_2 to SO_4~(2-)was faster than that of NOXto NO_3~-. The difference between the hourly averages of Na+and K+during the haze episode and clean days was small, implying that straw combustion and sea salt had no significant effect on the occurrence of haze, and the backward trajectories of the air masses also conformed with this result. The air pollutants were difficult to disperse because of the significant decrease in the planetary boundary layer(PBL) height. Relative humidity played a crucial role in the formation of haze by leading to hygroscopic growth of the diameter of aerosols. 相似文献
848.
Robert I. McDonald 《The Environmentalist》2006,26(4):221-225
Environmental scientists are continually discovering new and emerging environmental problems. There have been many studies
of how a particular environmental problem has occurred, its costs to society, and its (potential) resolution. However, to
date there have been few studies of the rate at which new environmental problems are generated by human technological innovations.
In this note, I present a conceptual framework that will help quantify how many now-unknown problems we may expect to occur
in a given sector. Two brief case studies illustrate the difficulty of finding appropriate dataset for fitting the full model,
however. Policy implications of the conceptual framework are discussed, with different kinds of economic sectors requiring
different approaches. 相似文献
849.
本文对我国加入WTO后我国的环保产业和产业的环保问题进行了初步的探讨,认为我国在WTO框架下的环保问题可归集到两方面即:产业的环保化和环保的产业化,产业发展上,必须全面提升环保标准,推行环境认证,促使产品环保标准提高,增强产品的国际竞争力;在环保产业本身的发展上,必须改革原有体制,和国际企业深度合作,培育规范市场,加快环保核心技术的开发,促使环保企业重组,走产业化,规模化的发展方向。 相似文献
850.
1991-1992年对重庆市郊若干酸化水体的生物待正与理化参数进行综合研究的结果表明,藻类的种类数、细胞密度、生物量和叶绿素a含量以及浮游动物的种类数等均与呈正相关,但与H+和总Al浓度呈负相关。浮游动物的个体密度在酸化水体中明显下降,但是鱼的捕食作用掩盖了其与上述化学参数之间的相关性。水体中H+和总Al浓度的增加在很大程度上对浮游生物产生了不利影响,水体的透明度、总Al.TP和SO与pH的相关性十分明显,r值分别为-0.6375、-0.6868、0.7561和0.7323。 相似文献