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61.
The role of humic substances in chromium sorption onto natural organic matter (peat) 总被引:5,自引:0,他引:5
To elucidate mechanisms of Cr3+ sorption onto the unaltered solid natural organic matter, the comparative studies of this ion binding from a solution at pH 4.0 onto three selected particle size fractions: 2000–1000 μm, 630–200 μm and 63–20 μm of markedly different HS content and structure, separated by a wet sieving from an overall sample of peat (Brushwood Peat Humus) were carried out. Comparable patterns of COOH groups and CECt confirmed that for cation exchange capacity were responsible mainly cations connected with COO− functional groups. It was though found that aliphatic acids in the solid state did not take part in Cr3+ binding, thus the finest studied fraction 63–20 μm of the highest contents of functional groups showed the lowest sorption capacity for Cr3+, while similar patterns of sorbed Cr3+, soluble HS content and base CEC0 indicated that these parameters were directly interrelated. The base ion exchange processes determined by CEC0 (with Ca2+ as a predominant exchangeable cation) appeared to be not the major mechanisms responsible for Cr3+ sorption. For this metal, strong binding to insoluble large molecular weight organic pool two- to threefold prevailed over the ion exchange processes. Very low acid desorption indicated generally low mobility of Cr3+-organic compounds. 相似文献
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Reduction of Cr(VI) by peat and coal humic substances 总被引:2,自引:0,他引:2
Denis?M.?ZhilinEmail author Philippe?Schmitt-Kopplin Irina?V.?Perminova 《Environmental Chemistry Letters》2004,2(3):141-145
The reduction of Cr(VI) by humic substances from leonardite and peat was investigated by capillary zone electrophoresis at various pHs. Both humic materials reduced Cr(VI) at pH 5.4, but not at basic pH. The capacity of leonardite humic substances to reduce Cr(VI) was lower than that of peat humic substances. Fe(III) accelerated the reduction of Cr(VI) by peat humic substances, but not by leonardite humic substances. Cr(VI) reduction mechanisms are proposed. The coal humic substances seem more suitable for remediation of Cr(VI)-contaminated sites. 相似文献
65.
Dissolved Organic Matter in Forest Soils: Sources, Complexing Properties and Action On Herbaceous Plants 总被引:2,自引:0,他引:2
A. T. Kuiters 《Chemistry and Ecology》1993,8(3):171-184
Dissolved organic matter (DOM) is an important component of plant-soil systems. Its essential role in soil solution chemistry, soil-forming processes and its effects on biota, including soil fauna, bacteria, fungi and plants, is extensively documented in literature. in this contribution several forest leaf litter types are compared as sources of DOM and the released organics are subjected to gel permeation chromatography to reveal their molecular-size distribution. Moreover, complexing properties, as an indication for the podzolization potential of the litter leachates, were established. the occurrence and properties of DOM in different soil horizons were monitored beneath a stand of Scots pine. the effects of the different groups of soluble organics including phenolic, fulvic and humic acids, and of water-extractable humic substances on the performance of herbaceous plants of the forest floor are briefly reviewed. 相似文献
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Klumpp A Ansel W Klumpp G Belluzzo N Calatayud V Chaplin N Garrec JP Gutsche HJ Hayes M Hentze HW Kambezidis H Laurent O Peñuelas J Rasmussen S Ribas A Ro-Poulsen H Rossi S Sanz MJ Shang H Sifakis N Vergne P 《Environmental science and pollution research international》2002,9(3):199-203
EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites. 相似文献
69.
构建新型异养硫自养ABR反应器,以处理含高浓度高氯酸盐(ClO4-)废水,并探讨该工艺对不同浓度ClO4-的还原性能及硫酸盐(SO42-)的产生规律,同时解析ABR系统内生物量及胞外聚合物(EPS)的变化特性.结果表明:在HRT=12h,进水ClO4-浓度为300mg/L时,去除率可达99.60%,出水SO42-浓度稳定在150mg/L内.进水pH值为7.8~8.0,随着还原ClO4-浓度的升高,异养段出水pH值逐渐升高至8.0~8.3,自养段pH值则逐渐降低至6.6~6.9,异养协同硫自养ABR系统可实现酸碱的平衡.此外,提高进水ClO4-浓度可促进EPS的分泌,且异养段第一格室微生物分泌的EPS最多,其含量可达到102.46mg/(g·vss).EPS的分泌可以形成保护层以抵制外界的压力,同时也起到储备碳源和能源的作用. 相似文献
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In recent years there has been an increasing interest in the use of autohydrogenotrophic bacteria to treat nitrate from wastewater. However, our knowledge about the characteristics of extracellular polymeric substances (EPS) releasing by these activities is not yet very advanced. This study aimed to investigate the change in EPS compositions under various pH values and hydrogen flow rates, taking into consideration nitrogen removal. Results showed that pH 7.5 and a hydrogen flow rate of 90 mL/min were the optimal operating conditions, resulting in 100% nitrogen removal after 6 hr of operation. Soluble and bound polysaccharides decreased, while bound proteins increased with increasing pH. Polysaccharides increased with increasing hydrogen flow rate. No significant change of bound proteins was observed at various hydrogen flow rates. 相似文献