STUDY OF COPPER(II) ASSOCIATION WITH DISSOLVED ORGANIC-MATTER IN SURFACE WATERS OF 3 MEXICAN COASTAL LAGOONS

Copper binding by dissolved organic matter has been evaluated by potentiometric titrations on surface waters from three Mexican coastal lagoons. A copper-selective electrode technique was utilized to measure cupric ion activity. A model that accounts for the variation in binding intensity as a function of the degree of surface loading was employed to calculate the binding constants of the complex formation between cupric ion and the organic ligands in solution. Small amounts of strongly complexing ligands were found to be present in the dissolved organic fraction. These naturally occurring ligands may be responsible for the availability of some micronutrients and for the inac-tivation of toxic heavy metals in the studied lagoons. © 1990, American Chemical Society. All rights reserved.