Role of free radicals in the binding of organochlorine pesticides and heavy metals with humic acid

The formation of soluble complexes between humic acid HA. and g-HCH or different metals Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn,Pb, Cd, As and Mg. was studied, along with any generation of free radicals by electron spin resonance spectroscopy. Free radical generation was noticed in case of interaction of humic acid with g-HCH, Cu and Cr. A hyperfine splitting pattern was noticed only in case of Mn. However, with Ca, Cd, Pb, As, Ni, Co, Zn and Fe, neither free radicals were generated nor hyperfine splitting was observed. The possible significance of free radicals in the binding of environmental pollutants with humic acid is discussed together with ecotoxicological implications.