Resumo

GARCIA-ARAGON, Juan Antonio et al. Fe and Mn Transport and Settling Modelling in the Upper Course of the Lerma River. Ing. invest. y tecnol. [online]. 2013, vol.14, n.3, pp.355-367. ISSN 2594-0732.

A metal transport and deposition model together with concentration measurements of Fe and Mn was developed in the Upper Course of the Lerma River, Mexico State. The hydraulic sections of 27.9 km of the Lerma River were measured in the field in order to supply the numerical model. A general mass balance equation considering full mixing in selected reaches of the Lerma River was developed and solved using the finite-difference method. At the same time a sampling campaign of water and sediment allowed us to obtain Fe and Mn concentrations in each phase. Metal concentrations were obtained by Energy Dispersive X-Ray Fluorescence Method (EDXRF). Partition coefficients for water and suspended sediment and for water and deposited sediment were calculated. Well defined periods and areas of deposition of Fe and Mn were obtained by the transport model and the spatial variation of the partition coefficients agree with the pattern obtained in the simulation. It is concluded that the current practice of constant values of the partition coefficients could not be used in modelling transport and deposition of metals if we are dealing with hydrologic extreme events and river sediment deposition areas.

Palavras-chave : sediments; Fe; Mn; partition coefficients; EDXRF; Lerma River.