Trace metals and metal-organic interactions in natural waters

Enrichment of nickel and cobalt in natural hard water by Donnan dialysis

“…This may be due to the fact that a number of interferences are present in natural waters. The interferences include surfactants which can foul the membrane (8), chelating agents (9,10), and an unknown and usually high ionic strength. These factors can interfere with the enrichment technique by altering the ion transfer rate across the membrane.…”

Chelators and Metal Buffering in Fermentation

“…Bjerrum's fundamental study of metal-aminc formation4 led to the use of metal chelators for analytical purposes33. The importance of metal ions for biological systems, and the selective toxicity which occurs if some of these metals are chelated, have been stressed by several authors.1 •2-10 In the same way as hydrogen ions are regulated by pH-buffering systems, metal ion buffering is made possible by means of sequestering agents or chelators. Examples of such naturally occurring metal-buffering systems are blood plasma, where the partition of metals between amino acids has been calcu lated30, or seawater, where metal-organic interactions may influence the growth of algae.1'- 35 We are of the opinion that such buffering systems affect the growth and detailed behaviour of all cells, and will be present in all complex mixtures of organic compounds. We believe1' that natural chelators will act both during the extraction of metals from mall particles, and in regulation of the availability of these metals to the yeast cell.…”

Removal of Humic Substances from Water with Granular Activated Carbons

“…Humic substances are characterized by complex-forming properties [7,8]. The formation of complexes is one of the reasons for the leachability of heavy metals from the soil by humic substances (their content in water increases) and the reason for the increased concentration of Fe and Mn in peat waters.…”