Effect of Dissolved Oxygen on Redox Potential and Nitrate Removal in Flooded Swamp and Marsh Soils

Abstract

The O2 depletion rates, NO3− loss, and the effects of added O2 on NO3− disappearance and redox potential in four flooded or intermittently flooded soils from the swamp and coastal marshes of Louisiana were quantitatively characterized in a laboratory study. The NO3− added either to the shallow floodwater or mixed with the soil in a suspension rapidly disappeared. Eighty to ninety parts per million NO3− was lost from the soil suspensions in 1 to 4 days and from the floodwater over a soil in 10 to 20 days. No NO3− was lost from floodwater separated from the soils. Oxygen depletion in the soil suspensions occurred in 15 minutes to 4 hours. Redox potential curves exhibited a characteristic inflection after O2 disappearance in all soils studied. Nitrate disappearance did not appear to be inhibited by as much as 16 ppm O2 dissolved in the soil suspensions because the O2 was rapidly consumed.

Direct Measurement of Denitrification Using 15 N‐labeled Fertilizer Applied to Turfgrass

“…Nitrogen losses through denitrification vary greatly and are highly variable across relatively small areas depending on NO 3 levels, moisture status of the soil, available organic matter, microbial distribution, and temperature (Engler et al, 1976; Robertson and Tiedje, 1987; Saad and Conrad, 1993). Spatial and temporal variability of N 2 O and N 2 emission from field soils and grasslands has been well documented by several investigators (Rolston et al, 1978; Ryden et al, 1978; Robbins et al, 1979; Bremner et al, 1980, 1981; Mosier et al, 1981; Blackmer et al, 1982; Parkin, 1993; Velthof et al, 1996) and greatly complicates quantification of N 2 O and N 2 emissions in the field.…”

Effect of soil salinity on the electro-chemical and chemical kinetics of some plant nutrients in submerged soils

“…After oxygen has disappeared from a water-logged soil, the need for electron acceptors for facultative anaerobic and true anaerobic organisms results in the reduction of several oxidized components. However, Engler et al 6 found that nitrate loss does not appear to be inhibited by the presence of a small amount of molecular 02 in flooded soils. If an energy source is available to the micro-organisms, nitrate, the higher oxides of manganese, hydrated ferric oxides and sulfate will be reduced.…”

A conceptual model of nutrient cycling in wetlands used for wastewater treatment: A literature analysis

“…The absence of molecular oxygen is due to the extremely slow rates of gas exchanges between soil and air when the soil is saturated with water {Ponnameruma 1972L Furthermore, the molecular oxygen penetrating the soil is rapidly utilized by aerobic and facultative anaerobic microorganisms (Engler et al 1976). Only a very thin layer in the soil-water interface remains in an oxidized state.…”

“…Studies of the factors controlling the oxygenated layer showed that both microbial respiration and chemical oxidation of iron (II} control its thickness {Hutchinson 1957;Ponnameruma 1972}. The importance of the layer in nutrient cycling is related to (a} its capacity to sorb and retain compounds such as phosphate, silica, manganese, cobalt, nickel, and zinc that are present in the supernatant water or diffused .from the reduced zone below {Engler et al 1976;Ponnameruma 1972}, and (b) its ability to cause nutrient transformations such as nitrification~ which releases nitrate to the water column ( Keeney 1972).…”