Degrees of pyritization in the Gulf of Mexico in sediments influenced by the Coatzacoalcos and the Grijava-Usumacinta rivers

Abstract

Degrees of pyritization (DOP) were measured by three different methods in four cores collected in the Gulf of Mexico, close to the outlet of the Coatzacoalcos and Grijalva-Usumacinta rivers. The extractants used for measuring labile Fe, necessary for the calculation of DOP values, were HCl 1N, dithionite and oxalate, with the first two ones being equivalent for measuring DOP, at least in this type of sediments. The data obtained in this work suggest that in deltaic sediments it is possible to find DOP values higher than those measured in the continental shelf of the Gulf of Mexico, with the sediments closer to the outlets of the Coatzacoalcos and Grijalva-Usumacinta rivers showing values that are even higher than those measured in the Mississippi River delta.