Phosphorus distribution pattern in sediments of natural and constructed wetlands

•Natural wetlands (NW1 and NW2) and constructed wetlands (CW1 and CW2) were studied.•Similarities in water composition between NW2-CW1 and between NW1-CW2 were found.•Water similarities were reflected in P accumulation and distribution in sediment.•Low OM content and dominance of inorganic P forms indicate low P mobility in sediment.•Study wetlands are highly efficient and sustainable in terms of P retention. Two constructed wetlands for treating industrial and sewage effluents (CW1 and CW2) and two natural wetlands (NW1 and NW2), located in Argentina, were studied. The aims of the study were (1) to assess the accumulation and distribution pattern of P in the surface sediments of both natural and constructed wetlands, and (2) to evaluate P long-term retention in sediment. In the sediment of all study sites, inorganic P fractions were dominant. Similar incoming water composition was determined between NW2 and CW1 and between NW1 and CW2. Water composition governed P concentration and distribution in sediment, being mainly P bound to CaCO3 in CW1 and NW2 and bound to Fe(OOH) in NW1 and CW2. According to water and sediment characteristics, the four wetlands will continue removing P from water. Studied wetlands are efficient and sustainable in terms of P retention.