Phosphorus sorption on marine carbonate sediment: Phosphonate as Model Organic Compounds

Organophosphonate, characterized by the presence of a stable, covalent, carbon to phosphorus (C–P) bond, is a group of synthetic or biogenic organophosphorus compounds. The fate of these organic phosphorus compounds in the environment is not well studied. This study presents the first investigation on the sorption of phosphorus (P) in the presence of two model phosphonate compounds, 2-aminothylphosphonoic acid (2-AEP) and phosphonoformic acid (PFA), on marine carbonate sediments. In contrast to other organic P compounds, no significant inorganic phosphate exchange was observed in seawater. P was found to adsorb on the sediment only in the presence of PFA, not 2-AEP. This indicated that sorption of P from phosphonate on marine sediment was compound specific. Compared with inorganic phosphate sorption on the same sediments, P sorption from organic phosphorus is much less in the marine environment. Further study is needed to understand the potential role of the organophosphonate compounds in biogeochemical cycle of phosphorus in the environment.

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► P sorption on marine sediment in the presence of two model phosphonate compounds was conducted.
► No phosphate change in water was found in the processes of phosphonate sorption.
► P was found to adsorb on the marine carbonate sediments in the presence of PFA, but not 2-AEP.
► P sorption on marine carbonate sediment was compound specific.
► Sorption from organic P compounds is much weaker than that of phosphate on sediments.