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

  • Drozdova, O Yu1
  • Aleshina, A R2
  • Tikhonov, V V3
  • Lapitskiy, S A4
  • Pokrovsky, O S5
  • 1 Geological Faculty, Moscow State University, Leninskie Gory 1, 119234, Moscow, Russia. Electronic address: [email protected]
  • 2 Geological Faculty, Moscow State University, Leninskie Gory 1, 119234, Moscow, Russia; Scientific Geoinformation Center of Russian Academy of Sciences, New Arbat 11/1, 119019, Moscow, Russia.
  • 3 Faculty of Soil Science, Moscow State University, Leninskie Gory 1/12, 119234, Moscow, Russia.
  • 4 Geological Faculty, Moscow State University, Leninskie Gory 1, 119234, Moscow, Russia.
  • 5 Geoscience and Environment Toulouse, UMR 5563 CNRS, University of Toulouse, 14 Avenue Edouard Belin, 31400, Toulouse, France; Institute of Ecological Problems of the North, N. Laverov Federal Center for Integrated Arctic Research, Nab. Severnoi Dviny 23, 163000, Arkhangelsk, Russia; BIO-GEO-CLIM Laboratory, Tomsk State University, Lenina Pr. 35, 634050, Tomsk, Russia. , (France)
Published Article
Publication Date
Feb 14, 2020
DOI: 10.1016/j.chemosphere.2020.126216
PMID: 32087384


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 on bacterial development. Therefore, while sizeable transformation of the organic and metal colloidal load of peat water may occur over first 10 days of UV-irradiation, the enhanced bioavailability of UV-treated substrate is achieved after first day of exposure. The present study demonstrates the importance of even short-term UV-irradiation on colloidal transformation and potential bioavailability of humic waters from temperate mires and highlights the need for more detailed study of coupled metal-organic matter transformation induced by sunlight exposure of mire waters. Copyright © 2020 Elsevier Ltd. All rights reserved.

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