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Denitrification: An Important Pathway for Nitrous Oxide Production in Tropical Mangrove Sediments (Goa, India)
Author(s) -
Fernandes Sheryl Oliveira,
Bharathi P.A. Loka,
Bonin Patricia C.,
Michotey Valérie D.
Publication year - 2010
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2009.0477
Subject(s) - nitrous oxide , denitrification , mangrove , nitrite , nitrification , environmental chemistry , environmental science , nitrate , ecosystem , greenhouse gas , nitrogen , chemistry , ecology , biology , organic chemistry
Net nitrous oxide production and denitrification activity were measured in two mangrove ecosystems of Goa, India. The relatively pristine site Tuvem was compared to Divar, which is prone to high nutrient input. Stratified sampling at 2‐cm intervals within the 0‐ to 10‐cm depth range showed that N 2 O production at both the locations decreased with depth. Elevated denitrification activity at Divar resulted in maximum production of up to 1.95 nmol N 2 O‐N g −1 h −1 at 2 to 4 cm, which was three times higher than at Tuvem. Detailed investigations to understand the major pathway contributing to N 2 O production performed at Tuvem showed that incomplete denitrification was responsible for up to 43 to 93% of N 2 O production. Nitrous oxide production rates closely correlated to nitrite concentration ( n = 15; r = −0.47; p < 0.05) and denitrifier abundance ( r = 0.55; p < 0.05), suggesting that nitrite utilization by microbial activity leads to N 2 O production. Nitrous oxide production through nitrification was below detection, affirming that denitrification is the major pathway responsible for production of the greenhouse gas. Net N 2 O production in these mangrove systems are comparatively higher than those reported from other natural estuarine sediments and therefore warrant mitigation measures.