We used a sequential extraction technique to compare the forms and amounts of particulate phosphorus (PP) deposited in the top meter of sediment spanning salinities from 0 to 10 in three Chesapeake Bay subestuaries: the Potomac, Choptank, and Bush Rivers. Fe-bound P (i.e., citrate-bicarbonate-dithionite (CDB)-extractable P) was the most dynamic fraction of PP, dominating oligohaline (salinity <3) sediments, but declining to near zero with depth in the most saline sediments of all three subestuaries. In contrast, we previously found Fe-P dominating the sediment PP at salinities ranging 0–11 in the Patuxent subestuary. Particulate organic P was relatively constant with depth and salinity and became the dominant form of PP in the most saline sediments. Fe-P was not replaced with diagenetic authigenic carbonate fluorapatite. In all the subestuaries, Fe-P generally persisted in the oligohaline sediments to 1 m depth, where sediment ages ranged from 60 to 200 years, based on 210Pb dating. At one site, PP burial reflected changing P loads from a nearby wastewater treatment plant. About 67% of the PP discharged from the Potomac watershed at the head of tide was buried in the sediments in the upper reaches of that subestuary. The form and amount of PP buried depended on the amount of CDB-extractable Fe in the sediments and on the distribution of sediment deposition along the salinity gradient. Even though CDB targets iron oxides, the predominant form of Fe in the sediments was ferrous iron suggesting that the predominant form of PP in oligohaline sediments may be ferrous phosphate.