A multi-technique investigation of copper and zinc distribution, speciation and potential bioavailability in biosolids.

The use of biosolids in agriculture continues to be debated, largely in relation to their metal contents. Our knowledge regarding the speciation and bioavailability of biosolids metals is still far from complete. In this study, a multi-technique approach was used to investigate copper and zinc speciation and partitioning in one contemporary and two historical biosolids used extensively in previous research and field trials. Using wet chemistry and synchrotron spectroscopy techniques it was shown that copper/zinc speciation in the biosolids was largely equivalent despite the biosolids being derived from different countries over a 50 year period. Furthermore, copper speciation was consistently dominated by sorption to organic matter whereas Zn partitioned mainly to iron oxides. These data suggest that the results of historical field trials are still relevant for modern biosolids and that further risk assessment studies should concentrate particularly on Cu as this metal is associated with the mineralisable biosolids fraction.

Comparison of the lead 168-nm and 220-nm analytical lines in high iron and aluminium matrices by inductively coupled plasma-optical emission spectrometry.

Virtually all photomultiplier-based inductively coupled plasma spectrometers (ICPS) use the lead (Pb) 220.3-nm analytical line, even though it has severe background continuum and interelement interference from the aluminium (Al) 220.4-nm line, and background shift due iron (Fe). Many Pb analytical lines above 220 nm are unsuitable due to poor detection limits. There are no reports in the literature on the use of Pb analytical lines below 220 nm, especially the 168.2-nm line recommended by Spectro Analytical (Kleve, Germany). The Pb 168-nm analytical line has a superior detection limit and is less prone to matrix, background continuum radiation and inter-element interference from high concentrations of Al and Fe compared to the Pb 220-nm analytical line. This has been demonstrated by the better precision and accuracy of analysis of soils containing high levels of Al and Fe.