EPA Method 2861

Recent research investigating the relationship between water chemistry and aluminum (Al) toxicity to aquatic organisms has been published (Adams et al. 2018; Cardwell et al. 2018; DeForest et al. 2018; Gensemer et al. 2018; Santore et al. 2018; Wang et al. 2018). Toxicity was shown to vary as a function of pH, dissolved organic carbon (DOC), and hardness, with biological responses correlating with total Al.

No direct relationship between dissolved Al and toxicity was shown for a wide variety of aquatic organisms in chronic toxicity studies. The publications mentioned in the previous paragraph have clearly demonstrated that, although toxicity of Al can be explained by the dissolved Al3+ at pH 5.0 or lower, the toxicity of Al in circumneutral waters does not correlate with dissolved Al.

This is in contrast to the transition metals (e.g., cadmium, copper, lead, nickel, zinc). For these metals the US Environmental Protection Agency (USEPA) has based its criteria on the dissolved fraction (US Environmental Protection Agency 1993). Toxicity of Al appears to be attributable to both ionoregulatory effects at acidic pH values and physical effects at neutral or alkaline pH conditions. Physical effects are often reported as asphyxiation attributable to coating of the respiratory membranes with Al hydroxide precipitates (Witters et al. 1996; Gensemer and Playle 1999; Teien et al. 2006).