Coagulation of organo-mineral colloids and formation of low molecular weight organic and metal complexes in boreal humic river water under UV-irradiation.

Coagulation of organo-mineral colloids and formation of low molecular weight organic and metal complexes in boreal humic river water under UV-irradiation.
Chemosphere. 2020 Jul;250:126216
Authors: Drozdova OY, Aleshina AR, Tikhonov VV, Lapitskiy SA, Pokrovsky OS
Abstract
Photodegradation of dissolved organic matter (DOM) is highly important in humic waters of peatland regions, yet the coupling between organic and organo-mineral colloids, trace metals and bioavailability of photodegraded products is poorly known. Here we studied photo-destruction of organo-mineral colloids induced by UV-irradiation of sterile-filtered mire water. We revealed two simultaneously occurring processes of transformation of DOM and trace elements speciation: (i) disintegration of high molecular weight organo-mineral colloids into lower molecular weight (<1 kDa) DOM and metal complexes and (ii) formation of particulate (>0.22 μm) aggregates of metals and organic matter. Over 26 days of UV-irradiation, up to 20% of dissolved organic carbon from peat waters was transformed into CO2. In addition to transformation of organic compounds, sizeable change in speciation and size fractionation of many trace metals such as Fe, Pb, Cd, Co, Zn, Cu, V, La, Ni and Cr occurred. Although short-term (1 day) UV-irradiation of mire water stimulated growth of cultivable Pseudomonas sp. bacterium, the long-term exposure (26 days) of organic substrate had a negative effect...

Source: Chemosphere - May 29, 2020 Category: Chemistry Authors: Drozdova OY, Aleshina AR, Tikhonov VV, Lapitskiy SA, Pokrovsky OS Tags: Chemosphere Source Type: research