Formation of phosphine and its effect on phosphorus retention in constructed wetlands: Characteristic and mechanism

Abstract

Phosphine (PH 3 ) is widely present in the atmosphere and plays an essential role in the global phosphorus cycle. However, its source and sink are currently unclear. In this study, the fate and mechanism of PH 3 production in lab-scale constructed wetlands (CWs) were investigated. The results showed that gaseous PH 3 release from CWs mainly occurred in the later stage of the operation cycle. The dissolved PH 3 concentration in the CW effluent varied from 2.73 to 4 . 08 μ g ⋅ L −1 , and the matrix-bound PH 3 content in the CWs varied from 2.60 to 16.39 ng ⋅ kg −1 . Moreover, the formation and migration of PH 3 in CWs could increase the proportion of available phosphorus and subsequently increase the phosphorus adsorption capacity by 103.6%. An exogenous electron donor promoted the production of nicotinamide adenine dinucleotide and subsequently increased the production of PH 3 . This study revealed a new biological pathway to enhance phosphorus removal by CWs, which should shed light on their sustainable operation. • PH 3 production characteristics in CWs were explored. • The existence of PH 3 increased the proportion of available phosphorus. • Dissolved PH 3 in the effluent of CWs might promote cyanobacteria bloom outbreaks. • PLA addition increased PH 3 production through acceleration of NADH formation.