Nitrate levels modulate denitrification activity in tropical mangrove sediments (Goa, India)

Abstract

A study to examine the short-term effect of nitrate and organic carbon addition on denitrification activity was carried out on sediments from a mangrove ecosystem prone to anthropogenic activities (Divar, Goa, India). Laboratory microcosms were prepared using sediment sectioned at every 2-cm-depth interval from the surface to 10 cm. The incubations were subjected to varying nitrate amendments at concentrations ranging from 0, 5, 10, 20, 40 to 60 μmol l(-1) (up to three times more than measured in field). Nitrous oxide production rates increased significantly (n=15; p<0.001) on addition of the nutrient at all depths investigated indicating that denitrification in mangrove sediments was NO[Formula: see text] limited. Incubations amended with organic carbon were prepared using glucose as a substrate with concentrations ranging from 0%, 0.1%, 0.3%, 0.5%, 0.75% to 1%. No significant increase in N2O production was observed on organic C addition. When both the substrates were in excess (1 mmol KNO3+1 mmol glucose), potential denitrification rates decreased with depth and were up to 38 times higher than the in situ denitrification activity varying from 81.26 to 304.09 μmol N2O-N m(-2) h(-1). These results reveal that mangrove sediments could act as a sink for nitrate and microbially mediated denitrification could effectively reduce N load controlling any adverse environmental impact in the adjoining estuarine system.

Nitrous Oxide Emission From Sediment of a Tropical Mangrove Forest in Central Vietnam-Implications of Short-Term Laboratory Experiments

“…3), indicating that NO3 -was a limiting factor for N2O emission. Our result is in agreement with previous studies 13) 32)33) . King and Nedwell (1987) 33) showed that the bacterial communities responsible for N2O emission were adapted to changes in NO3 -concentrations.…”

“…Nitrous oxide emissions depend on numerous factors such as NO3 -concentration, oxygen levels, pH, salinity, temperature, organic matter availability and microbial population 8)9)10)11) . Regarding geographical distribution, mangroves are found in South China 12) , Taiwan 4) , Puerto Rico 2) , India 3) 13) , Australia 14) . There are considerable uncertainties about sediment properties and environmental conditions in mangroves that would affect N2O emission.…”

“…, Fernandes and Loka (2011) 13) and Kreuzwieser et al (2003) 14) investigated the effects of NO3 -on potential denitrification and N2O emission using a wide range of NO3 -concentrations. They showed that N2O emissions in a mangrove were NO3 -limited.…”

Implications of Benzoate Induced Alterations in Cell Morphology and Physiology in Pseudomonas aeruginosa TMR2.13 for Potential Application in Bioremediation and Monitoring Approaches

“…The abundant organic matter in coastal and estuarine systems generates favourable conditions for the heterotrophic denitrifiers to proliferate [14]. However, in such ecosystems, the persistent accumulation of aromatic hydrocarbons will inevitably render an effect on the physiological activities of the autochthonous microbial communities [12], such as, membrane transport [15], denitrification [16] and pigment production [17].…”

Effects of soil type and nitrate concentration on denitrification products (N2O and N2) under flooded conditions in laboratory microcosms

“…These areas include flooded rice fields (Reddy and Patrick 1986;Buresh and De Datta 1990), riparian wetlands (Hefting et al 2004;Van den Heuvel 2010) and mangrove forests (Chiu et al 2004;Fernandes and Loka 2011). In such flooded soils, the main products of denitrification (N 2 O or N 2 ) were dependent on environmental conditions.…”