UNDERSTANDING THE OXIDATION RATE OF THE ORGANIC MATTER IN SURFACE WATER THROUGH CONTROLLED IN-VITRO EXPERIMENT

Pramita Majumder

Department of Applied Geology, Ballygunge Science College, Calcutta University, Kolkata-700019

Dr. Melinda Kumar Bera

Assistant Professor, Department of Geology and Geophysices, Indian Institute of Technology, Kharagpur, Paschim Medinipur 721302

Abstract

The oxidation of the organic matter (OM) present in the surface water, occurs through multiple oxidation processes which include both microbially mediated oxidation and photo-oxidation. Since both of them produce CO₂ and CO, and directly contribute to the Dissolved Inorganic Carbon (DIC), it is unknown which one of the above mentioned processes is dominant for producing DIC in the surface water. Further, the rate at which the above mentioned processes operate over different plant type (C3 vs. C4) and their body parts (leaf, stem, root), is also unknown. Recent studies have suggested that microbial degradation of the C4 plant produced OM is faster than the C3 plant produced OM when present in soil. The present project thus aims at understanding the OM degradation rate in the surface water, during photo-oxidation and microbially mediated oxidation process exclusively, through controlled in-vitro experiment. During the experiment, C3 and C4 plant produced organic matter (Leaf, stem, and root) were kept dipped in water in closed system and allowed to undergo oxidation through different processes separately. The concentration of the DIC produced by the oxidation of the organic matter was then measured to understand the rate of organic matter oxidation. Irrespective of the plant type and their parts, the results of the experiment show a consistently low DIC production during photo-oxidation with respect to the microbial oxidation. Further, the consistently higher DIC production during microbial oxidation of the C4 plant clearly indicates a higher degradation rate for C4 plant material than C3 plant, as suggested from the experiments conducted on soil.

Keywords: oxidation, microbially mediated oxidation, photo-oxidation

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