Regresar

Hidden contribution of shrimp farming effluents to greenhouse gas emissions from mangrove soils

Abstract:

In the present study, we evaluated CO 2 , CH 4 , and N 2 O fluxes in mangrove soils that receive shrimp farming effluents. Soil and gas samples were collected from a mangrove that receives the discharge of shrimp pond effluents and another mangrove forest free of the effluent impacts. CO 2 and N 2 O emissions were significantly higher in the mangrove soil affected by the shrimp effluents (51.4 mg m 2 h −1 and 90.9 μg m −2 h −1 , respectively) than in the mangrove soil free of the effluents (26.5 mg m −2 h −1 and 40.4 μg m −2 h −1 , respectively). No significant differences in CH 4 emissions were observed between the two mangroves soils (mean values ranging from 0.2 to 0.8 mg m −2 h −1 ). Suboxic conditions govern nitrification-denitrification and mineralization processes and control CO 2 and N 2 O emissions from the soil; however, CH 4 fluxes were not affected. The highest emissions from the impacted soil (93% higher for CO 2 and 125% higher for N 2 O) were attributable to the high content of organic carbon, total nitrogen, and potentially mineralizable nitrogen, which reduce the role of the mangrove in mitigating greenhouse gas emissions.