Experimental study on phosphorus release from sediment with fresh-water snail (Bellamya aeruginosa) bioturbation in eutrophic lakes

Abstract

To study the effects of snail (Bellamya aeruginosa) bioturbation on phosphorus (P) mobility in sediment and the relevant mechanisms behind them. A microcosm simulation experiment was carried out at millimeter resolution with an 89 days culture of homogeneous sediments. High-resolution dialysis (HR-Peeper) and diffusive gradient in thin films (DGT) techniques were utilized to simultaneously acquire the vertical distribution of soluble and labile P/iron (Fe) in bioturbation sediments. Snail bioturbation significantly enhanced soluble reactive P (SRP) and labile P concentrations, with the maximum increment to 306% and 1133% of the control sediments within the influence depths from 0 to − 30 mm and to − 20 mm, respectively. The P fluxes released from the sediment–water interfaces in snail treatments were correspondingly enhanced with the maximum increments to 218% of the control. Also, snail bioturbation significantly enhanced the soluble Fe(II) and labile Fe concentrations by maximum increment of 218% and 199% of the control within 0 to −24 mm and − 19 mm, respectively. The high correlation between soluble/labile P and Fe suggested that P release from the sediment under snail bioturbation was due to the reduction and dissolution of Fe(III) oxyhydroxide.