Application of a modified BCR sequential extraction (three-step) procedure for the determination of extractable trace metal contents in a sewage sludge amended soil reference material (CRM 483), complemented by a three-year stability study of acetic acid and EDTA extractable metal content.

This paper provides additional data on a sewage sludge amended soil certified reference material, CRM 483, which was certified in 1997 for its EDTA and acetic acid extractable contents of some trace metals, following standardised extraction procedures. The additional work aimed to test the long-term stability of the material and the applicability of an improved version of the BCR three-step sequential extraction procedure on the sewage sludge amended soil (CRM 483). The paper demonstrates the CRM 483 long-term stability for EDTA and acetic acid extractable contents of Cd, Cr, Cu, Ni, Pb and Zn and gives the results (obtained in the framework of an interlaboratory study) for the extractable contents of the same elements in the CRM 483, following the BCR three-step sequential extraction scheme. The aqua regia extractable contents following the ISO 11466 Standard are also given. The data are given as indicative (not certified) values.

Column leaching and sorption experiments to assess the mobility of potentially toxic elements in industrially contaminated land.

Made-up ground collected from layers of a trial pit excavated on a former industrial site was treated with artificial rainwater in a series of column leaching and sorption experiments. Metal mobility and the ability of various layers of material obtained from the pit to act as sources or sinks of potentially toxic elements were assessed. Samples from different layers varied in their abilities to raise the pH of rainwater applied at pH 3.5 and 4.3, and this was reflected in the amounts of metals mobilised by the rainwater as it percolated through the soil column. Material from the top two layers of the pit released cadmium, copper, manganese, lead, nickel and zinc to the aqueous phase, but the lower layers, with higher buffering capacity, were able to resist acidification even when the equivalent of 12 months' rainfall (western UK) was applied. Column sorption experiments confirmed the ability of material from layer 4 (48-50 cm) to take up copper, manganese and zinc. Metals were determined in the leachates by flame and electrothermal atomic absorption spectrometry and principle anions by ion chromatography.

Extraction of ergosterol from peaty soils and determination by high performance liquid chromatography.

The ergosterol content of soil can be used as an indicator of fungal activity. A method has been developed for the extraction and determination of ergosterol in organic soils, as part of a study to assess the correlation between fungal activity and the sequestration of metal pollutants. The moisture content of the soil affected the extraction process. Four consecutive extractions with methanol removed >95% of the ergosterol that can be obtained from the fresh sample (63% moisture) by exhaustive extraction. By freeze drying the soils prior to extraction (a) up to 35% more ergosterol was extracted after a single extraction, (b) >90% of the recoverable ergosterol was collected in two extractions and (c) the repeatability of the extraction was improved. Storage of soil extracts in the absence of light prevents degradation of ergosterol. A previously reported method for determination of ergosterol by HPLC has been improved by modification of the eluant composition. With 46% methanol/46% acetonitrile/8% dichloromethane, ergosterol was eluted with good resolution approximately 8 min after injection of 20 mul of the extract. The detection limit of the HPLC method was 0.5 mug/ml ergosterol, equivalent to 0.06 mug/g in 25 g fresh soil. Changes in ergosterol contents of peaty soil treated with fungicide, and in samples of the peaty podzol and a humus iron podzol in the vicinity of fungal fruiting bodies, have been determined.

Trace element distribution and mobilization in Scottish soils with particular reference to cobalt, copper and molybdenum.

Total and extractable trace element contents have been determined in about 1000 soil profiles representing the main soil series occurring throughout Scotland. The frequency distributions of a number of trace elements in these soils are described and some relationships between total and extractable contents discussed. The geological nature of the soil parent material, soil texture, organic matter content and environmental contamination are the principal factors controlling soil total contents. Soil drainage class, because of its effect on mineral weathering and soil oxidation-reduction conditions, has a major influence on soil extractable contents, availability to plants and crop uptake. Particular attention is paid to cobalt, copper and molybdenum because of their importance for animal health in Scotland.