#05 2021

Elwandle Node extends its laboratory capacity

By Lucienne Human, Biogeochemistry Laboratory Platform Manager, SAEON Elwandle Node

The latest addition to the Elwandle Node’s biogeochemistry laboratory will extend the range of elements measured in the coastal environment. The new total reflection X-ray fluorescence (TXRF) benchtop instrument is capable of measuring trace and heavy metals from Magnesium to Americium in the part per billion (ppb) range.

Traditionally, this analysis was mostly performed by inductively coupled plasma (ICP) spectrometry, but technology has improved in XFR over the years – the TXRF is now at a stage where it rivals ICP analysis.

The principle behind the analysis is based on total reflection X-ray fluorescence analysis. Excitation of elements with an X-Ray beam causes them to emit light at their characteristic energies, which enables elemental identification. The magnitude of the energy emitted helps identify the concentration of elements present in a sample. The result is a chromatogram of available elements in a sample. The analysis can be done on both solids and liquid samples, making it a flexible instrument.

Although metals are found to occur naturally on the earth, they are becoming progressively more concentrated in the natural environment due to anthropogenic activities such as factories, mining and household products. Most non-essential metals such as Cadmium (Cd) and Lead (Pd) for example, have no functional significance for plants and animals and are toxic even in low concentrations. Within aquatic systems specifically, these non-essential metals often biomagnify across food chains and become more toxic with each trophic level.

The TXRF has already been put to good use with some ongoing projects on salt marsh plants, seagrass and sediment. Plans are now under way to initiate the first metal long-term ecological research (LTER) site on the continent at Swartkops Estuary.