Promising anti-pollutant: chelating agent NTA protects fish from copper and zinc

COPPER and zinc are surprisingly widespread pollutants of water. In wilderness areas they may endanger fish in otherwise clean rivers as the result of mining operations1. In British industrial areas, they commonly contribute an average of 23 per cent of total toxicity of mixed pollution for fish, and in some rivers a much higher proportion2. Furthermore, trace concentrations, one-tenth to one-twentieth of accepted standards for drinking water, can be lethal for fish in regions where surface water is very soft1. In such circumstances, year-round prevention of “spills” of metal pollution can be difficult. The trisodium salt of nitrilotriacetic acid (NTA) seems to be a promising “anti-pollutant”, to prevent fish-kills in case of short-term breakdown of normal pollution controls.