MECHANISM OF SEDIMENTATION OF DISSOLVED ORGANIC MATTER IN ESTUARIES

Abstract

To elucidate the changes in the molecular weight distribution of DOM as the salt background increases, the authors performed laboratory experiments in which we used ash-free humic acid (HA) and fulvic acid (FA) preparations extracted from the water of the Razdol'naya River. The model solutions of HA and FA, at concentrations of 3.0 mg C/liter, were mixed with water collected in the seaward zone of the estuary of that river. After standing for 24 hours, the equilibrium solutions were filtered through a membrane filter (0.45 μm). The humic and fulvic acid concentrations were determined spectrometrically at 330 nm. The molecular weight distribution of the humic and fulvic acids in solution was analyzed by exclusion chromatography on MVS-250-GKh and MPS-700-GKh substrates, using a KhZh-1303 liquid phase chromatograph. The refractometer detection technique was used to identify the colloidal fraction of DOM. Study results are discussed.