Sediment–Phosphorus Dynamics in the Yellow River Estuary

The Yellow River, with its extremely high sediment loads, and the Yellow River Estuary (YRE) serve as a vital conduit for material exchange between land and marine environments, where sediment–phosphorus interactions profoundly influence nutrient cycling, ecological health and eutrophication potential. This paper reviews the distribution of phosphorus in overlying water and sediment, the characteristics of phosphorus migration and transformation across the sediment–water interface, and the effecting factors of phosphorus migrate, such as sediment properties and environmental factors in the YRE. Inorganic phosphorus was the dominant form in the overlying water and sediment. Suspended sediment acts as a dynamic reservoir for phosphorus transportation in the YRE. The dynamic estuarine environment promotes sediment deposition, which helps reduce phosphorus levels in the water. Upon entering the Bohai Sea, sediment is transformed into the source of phosphorus. The released phosphorus may increase the nutrient load in shallow Bohai Sea waters. Fine particles demonstrate strong adsorption capacity for reactive phosphorus, acting as the primary carriers for phosphorus migration at the sediment–water interface. The grain size of the suspended sediment in the Yellow River exhibited significant sorting characteristics with varying sediment content, consequently affecting the forms of phosphorus. Likewise, the influence of biogeochemical conditions on the transport and transformation of sediment and phosphorus was further analyzed and the partial least squares-path model of related variables on estuarine phosphorus is constructed to interpret the behavior of sediment and phosphorus in the YRE. Finally, the current situation and indeterminacy of water quality models in the estuary were appraised. The priority of analyzing and revealing the environmental behaviors of phosphorus in a sediment-laden river estuary in the future was further proposed against the present deficiencies. This review holds significant practical importance for enhancing the assessment of ecological environment quality and ecological restoration in the YRE.