A comprehensive review of the sequential extraction schemes for metal fractionation in environmental samples (i.e., sediment, soil, sewage sludge, fly ash, etc.) is presented. The review contains more than 400 references and covers principally the literature published over the last decade. The use of each reagent involved in these schemes is looked at critically, and guidelines for their selectivity and extraction capacity are given. The operational character of these schemes is emphasised. Topics such as comparability between sequential extraction schemes of widespread use, harmonisation, acceleration, validation, etc. are addressed and future developments outlined.

Chemical sequential extraction for metal partitioning in environmental solid samples.

Cadmium toxicity and tolerance in vascular plants

Short-chain fatty acids (SCFAs) have attracted much attention recently because of their positive physiological effects. In this work, a rapid and reliable gas chromatographic method for determination of eight SCFAs, in colonic and faecal samples from rats and humans has been developed and validated. The methodology involves extraction of the SCFAs in water before a direct injection procedure on a FFAP capillary column. A stock standard solution containing acetic acid, propionic acid, n-butyric acid, i-butyric acid, n-valeric acid, i-valeric acid, n-caproic acid and n-heptanoic acid was prepared and used. A high linearity (r2 > 0.9990), low quantification limit (2.38-30.14 microm) and high recovery for most acids were obtained. Acidification of faecal samples was found to be crucial for quantitative determination of the SCFAs, and adjustment of pH to 2-3 was regarded as necessary. Glass wool inserted in the glass liner of the injection port proved effective in preventing the contamination of the column by non-volatiles, and 12% formic acid reduced the ghost peak that appeared gradually after several injections. After validation, the methodology was applied on two faecal samples from rats fed diets containing different amount of dietary fibre and one faecal sample from human fed a normal diet to test the accuracy of the developed method.

Rapid determination of short‐chain fatty acids in colonic contents and faeces of humans and rats by acidified water‐extraction and direct‐injection gas chromatography

For heavy metal-contaminated agricultural land, low-cost, plant-based phytoextraction measures can be a key element for a new land management strategy When agents are applied into the soil, the solubility of heavy metals and their subsequent accumulation by plants can be increased, and, therefore, phytoextraction enhanced An overview is given of the state of the art of enhancing heavy metal solubility in soils, increasing the heavy metal accumulation of several high-biomass-yielding and metal-tolerant plants, and the effect of these measures on the risk of heavy metal leaching Several organic as well as inorganic agents can effectively and specifically increase solubility and, therefore, accumulation of heavy metals by several plant species Crops like willow (Salix viminalis L), Indian mustard [Brassica juncea (L) Czern], corn (Zea mays L), and sunflower (Helianthus annuus L) show high tolerance to heavy metals and are, therefore, to a certain extent able to use the surpluses that originate from soil manipulation More than 100-fold increases of lead concentrations in the biomass of crops were reported, when ethylenediaminetetraacetic acid (EDTA) was applied to contaminated soils Uranium concentrations could be strongly increased when citric acid was applied Cadmium and zinc concentrations could be enhanced by inorganic agents like elemental sulfur or ammonium sulfate However, leaching of heavy metals due to increased mobility in soils cannot be excluded Thus, implementation on the field scale must consider measures to minimize leaching So, the application of more than 1 g EDTA kg(-1) becomes inefficient as lead concentration in crops is not enhanced and leaching rate increases Moreover, for large-scale applications, agricultural measures as placement of agents, dosage splitting, the kind and amount of agents applied, and the soil properties are important factors governing plant growth, heavy metal concentrations, and leaching rates Effective prevention of leaching, breeding of new plant material, and use of the contaminated biomass (eg, as biofuels) will be crucial for the acceptance and the economic breakthrough of enhanced phytoextraction

Enhancing phytoextraction: the effect of chemical soil manipulation on mobility, plant accumulation, and leaching of heavy metals.

Aminated polyacrylonitrile fibers (APANFs) were prepared through the reaction of polyacrylonitrile fibers (PANFs) with diethylenetriamine in a solution and were used as an adsorbent to remove lead and copper ions from aqueous solutions. It was found that the zero ζ potential point of the APANFs was at about pH = 8.1, in contrast with that of the PANFs at pH = 3.6, and the APANFs had significantly higher adsorption capacities for both lead and copper ions than the PANFs. The adsorption behaviors of lead and copper ions on the APANFs depended upon the solution pH values, and greater amounts of adsorption were obtained at higher solution pH values. Scanning electronic microscopy and atomic force microscopy indicated that the APANF had a rougher surface than the PANF, and the adsorption of the metal species on the APANF made the surface even rougher. Fourier transform infrared spectroscopy revealed that the amine groups on the surface of the APANF played an important role in the removal of lead and copper ion...

Aminated polyacrylonitrile fibers for lead and copper removal

The utilization of biomass residues as sources for natural chelates is a new approach to improve the ecological and economical balance of leaching techniques for the remediation of metal-polluted soils. Residues, such as molasses, blood meal, and silage effluents, containing various aliphatic carboxylic acids, sugar acids, and amino acids or their precursor compounds were selected, hydrolyzed and oxidized, if required, and analyzed for their organic constituents. Soils that were contaminated with metals via sewage sludge amendment were extracted in batch and column experiments at various pH values. Grass silage effluent removed ∼75% of Cd and >50% of Cu and Zn at pH 4.4. The neutralized effluent was less effective except for Cu (69% leached). The neutral blood meal hydrolysate extracted primarily Cu (55−66%) and Ni (38−67%). Metal bonds attacked by this extractant were identified using a sequential leaching procedure. Hydrolysates containing sugar acids mobilized Cu and Pb under alkaline conditions. The a...

D. Bieniek

Papers

Utilization of Biomass Residues for the Remediation of Metal-Polluted Soils

Synthesis of carboxyl group containing hydrazine-modified polyacrylonitrile fibres and application for the removal of heavy metals

Investigation of the binding of heavy metals in thermally treated residues from waste incineration

Determination of monomeric sugar and carboxylic acids by ion-exclusion chromatography

Heavy metal leaching of fly ash from waste incineration with gluconic acid and a molasses hydrolysate