Temporal Relation between Soluble Reactive Phosphorus and Factors in Stream Water and Sediments in Hoxie Gorge Creek, New York

Abstract

Temporal changes in soluble reactive phosphorus (SRP) were associated with sediment and streamwater factors in Hoxie Gorge Creek. Over the annual cycle, streamwater SRP was positively correlated with the zero equilibrium phosphate concentration (EPC0) of the sediments at two disparate sites. Phosphate release during biological decomposition of organic matter in the sediments may have been an important source of SRP at times of high temperature and low discharge at an upstream site. At a downstream site, with lower sediment organic content and ATP, geochemical processes in the sediments as influenced by Ca may have been partly responsible for long-term SRP variations. Short-term SRP changes measured during a storm event were linked by field and laboratory analyses to variation in streamwater Ca. During the storm, streamwater Ca and SRP were negatively correlated (r = −o 791; p < 0 05). Laboratory sorption experiments showed that EPC0 increased by 3.1 μg∙L−1 as Ca decreased by 4 mg∙L−1, simulating the change found during the storm. When streamwater Ca was experimentally increased by spiking with CaCl2 in the field, SRP decreased. Some temporal changes in streamwater SRP can be explained by interactions between sediments and streamwater Ca.