The aeration and dredging stimulate the reduction of pollution and carbon emissions in a sediment microcosm study

Sediment dredging and aeration are used as important technical measures to remediate internal loading of sediment in polluted rivers. However, previous studies have overlooked the impact of dredging and aeration on Greenhouse gases (GHGs) emission. We established three aeration rate(six different aeration intervals), one dredging treatment to investigate the effect of aeration and dredging on pollutant removals and CO₂, CH₄ and N₂O emissions. The results indicated the pollutants and GHGs at 2.4, 3.4, 4.4 L min^-1 aeration rates reached collaborative emission reduction after more than 3 h or within 1.5 h. Meanwhile, the GHGs fluxes after aeration decreased with the increasing aeration rate, with the mean CO₂, CH₄ and N₂O fluxes of 69.74, 0.16, 7.53 mg m^-2 h^-1 and 33.64, 0.09, 4.17 mg m^-2 h^-1 before and after aeration, respectively. With respect to dredging, the pollutants and N₂O reached synergic effects between reduction of pollution and carbon emissions after 1 h dredging. Specifically, the CO₂ and CH₄ emissions after dredging was lower than those of before dredging, but the N₂O emissions was higher than those of before dredging. In addition, our analysis revealed that the dissolved oxygen (DO), oxidation-reduction potential (ORP), available potassium (AK) and ammoniacal nitrogen (NH₄⁺-N) in the sediment influenced GHGs fluxes at the water-air interface in the aeration. Our study indicated moderate aeration and dredging can achieve the synergistic effect in reducing pollution and carbon emissions.