mstone@fes.uwaterloo.ca

Abstract Deltaic landforms are important sinks for a portion of the suspended sediment flux transported by many large river systems in the world. The trapping and subsequent deposition of fine-grained (< 63 m m) sediment by rooted aquatic plants has implications for the distribution of sediment-associated nutrients and contaminants in these ecologically diverse ecosystems. The present study examines the spatial distribution of chemically defined particulate phosphorus (P) forms [nonapatite inorganic P (NAIP), apatite inorganic P (AP), organic P (OP)] in a remote northern Canadian delta where sediment accumulation rates are influenced by delta morphology and plant assemblages. Sediment samples were collected in three morphological zones (outer, mid, apex) of the delta. The median total particulate P concentration was 329.2 m g P g^-1 ± 50 m g P g^-1. NAIP represented approximately 68% of particulate P in the delta but total particulate P concentrations are considerably lower than reported in the literature for mid-latitude river and lake environments. Macrophytes influence the spatial distribution of particulate P forms in the delta by influencing the patterns of sediment deposition and grain size.