Bioavailability of aluminium in the presence of humic substances at low and moderate pH.
Fish kills have been observed in lakes with low pH and high Al content. The monomeric inorganic Al seems to be the most acute toxic fraction. Humic lake waters, situated in acidified areas, often have high values of aluminium. However, the fraction of Al bound to humus is regarded as a relatively nontoxic form of Al. As pH is decreasing, the physical and chemical properties of humus change. The molecular size, electronegativity and colour decrease. An important question in this matter is the potential change in bioavailability of "Al-humus" as pH decreases. The bioavailability of the Al-humus complex was studied; in relation to surface water acidification and in relation to drinking water and human health. The work is based on the octanol/water partition coefficient (Khow), estimated by measuring the UV absorption at 254 nm. Al concentration is determined in the water phase and in the octanol phase. The results show that the amount of organic material soluble in the octanol phase relative to the amount in the aqueous phase increases with decreasing pH, while no Al is detected in the octanol phase. It is concluded that Al is only weakly bound to humus and consequently Al complexed with humus is of minor concern in bioaccumulation.
Gjessing
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ET
National Institute of Public Health, Oslo, Norway.
Riise
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G
Petersen
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RC
Andruchow
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E
D000535:Aluminum / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D001682:Biological Availability; D005399:Fishes; D006262:Health; D006801:Humans; D006863:Hydrogen-Ion Concentration; D014867:Water / Q000032:analysis*; D014876:Water Pollution; D014881:Water Supply
D014867:Water; D000535:Aluminum