Extractable trace elements

Figure 7.2. Ratios of DPTA-extractable trace elements in the rhizosphere over bulk Egyptian soils irrigated with sewage water for 10, 40, and 80 years (Data from El-Motaium and Badawy, 1999)...

Barbarick, K.A., Ippolito, J.A., Westfall, D.G. Extractable trace elements in the soil profile after years of biosolids application. J Environ Qual 1998 27 801-805. 

Archer, F.C. and Hodgson, I.H. (1987) Total and extractable trace element contents of soils in England and Wales. Journal of Soil Science 38, 421-431. 

Quevauviller, P., Rauret, G. Muntau, H., Ure, A.M., Rubio, R., Lopez-Sanchez, J.F., Fiedler, H.D. Griepink, B. (1994) Evaluation of sequential extraction procedures for the determination of extractable trace elements in sediments. 

Matrix-matched CRMs are increasingly needed for a range of environmental matrices, elements or compounds, including materials certified for of>erationally-defined parameters (e.g. extractable trace element contents). Finally, training on the preparation of LRMs and use of CRMs should be systematised in the framework of accreditation systems. Such courses already exist [46] but are not fitted for purpose with respect to accreditation they should involve advice on how to develop LRMs versus CRMs, use RMs in sectorial proficiency testing (e.g. environmental monitoring) etc. 

The techniques of final determination used to determine the extractable trace element contents were FAAS, ETAAS, ICPMS and ICP-AES. 

The stability of the extractable trace element contents was tested at -20, -i-20 and +40°C during a period of 12 months and the extractable contents of Cd, Cr, Cu, Ni, Pb and Zn were determined after 1, 3, 6 and 12 months. For the CRMs 483/484, the procedures used were the same as in the homogeneity study, with the exception of Pb for which ETAAS was used as final determination. No instability could be demonstrated and hence the materials were suited as candidate CRMs. In the case of CRM 600. the... 

The choice of the extraction procedures is described in detail elsewhere [18]. On the basis of the results of the first interlaboratory study [19], the choice of EDTA and DTPA for certification was discussed. Whereas EDTA was widely accepted, the choice of DTPA was more criticised because of its operational difficulties the wide use of the latter would, however, justify the certification of DTPA extractable trace element contents, providing that its limitations in comparison with EDTA were clearly identified. 

CRM 600 Calcareous loam soil - extractable trace elements Certified values for 5 EDTA- and 2 DTPA-soluble metals... 

General principles of calibration of course apply to speciation analysis. This step is often not sufficiently considered, since it is estimated that about 25-30% of erroneous data may be attributed to calibration errors this has been reflected, for example, in the BCR intercomparison on extractable trace elements in soil and sediment [24], where many laboratories were demonstrated to have errors when analysing a common calibrant solution. 

The CVs and the total uncertainty Ucv for the extractable trace element contents between (CVb) and within (CFw) bottles are given in Table 11.3. 

For the homogeneity study, the six elements were determined in each candidate CRM by analysing 10 subsamples taken from one bottle (within-bottle homogeneity test, S ) and one subsample in each of 20 different bottles selected during the bottling procedure (between-bottle homogeneity test, Sb). The CFs and the total uncertainty Ucv for the extractable trace element contents between (5b) and within (5w) bottles are given in Table 11.9. 

For total recovery of amorphous Fe oxides, treatment of samples with acidified ammonium oxalate (pH 3) in the absence of the catalyzing effect of light has been proposed (LeRiche and Wier, 1963 Schwertmann, 1964 McKeague and Day, 1966). This reagent has been extensively used for selectively extracting trace elements associated with amorphous Fe oxides (Shuman, 1979 Salomons... 

Keywords Danube River Basin, Sequential extraction, Trace elements... 

---