Denitrifying kinetics and nitrous oxide emission under different copper concentrations

Area of Science:

• Environmental microbiology
• Biogeochemical cycles

Background:

• Copper concentrations can influence microbial processes like denitrification.
• Nitrous oxide (N2O) is a potent greenhouse gas produced during denitrification.

Purpose of the Study:

• To investigate the effects of varying copper concentrations on denitrifying activity.
• To examine how copper impacts nitrous oxide (N2O) emissions from denitrifiers acclimated to different electron donors.

Main Methods:

• Denitrifying bacteria were acclimated in sequencing batch reactors using acetate or methanol as electron donors.
• Batch experiments were conducted to assess denitrifying activity and N2O emission under different copper concentrations.

Main Results:

• Denitrifying activity decreased with increasing copper concentrations for both acetate- and methanol-acclimated denitrifiers.
• Acetate-acclimated denitrifiers showed a more significant reduction in activity (89% at 1 mg/L copper) compared to methanol-acclimated ones (15%).
• Copper influenced N2O emission differently: it initially increased then decreased for acetate-acclimated denitrifiers, while it consistently decreased for methanol-acclimated denitrifiers.

Conclusions:

• Copper exerts a significant inhibitory effect on denitrifying activity, with greater impact on acetate-utilizing bacteria.
• The electron donor used for acclimation plays a crucial role in the response of denitrifiers to copper exposure.
• Copper's effect on N2O emission is complex and depends on both copper concentration and the specific microbial community's acclimation.