Phosphorus Retention Versus Mobility in Lake Sediments
Phosphorus (P) pollution from agricultural and urban sources can accelerate eutrophication in receiving water bodies and compromise water quality. Restoring good water quality to lakes that have been impaired by P pollution requires not only curtailing additional inputs of P but also patience. While some lakes efficiently bury P in their sediments, others readily release P from their sediments back into the overlying water. Lakes in the latter category can be expected to recover more slowly from previous pollution. We examine repeat sediment cores – collected at the same location but in different years – from a dozen Minnesota lakes to better understand the factors that control P retention versus mobility in lake sediments. By comparing P measurements at age-equivalent sediment depths, we also determine if P burial patterns in individual lakes describe historical pollution trends or if they instead reflect mobility within the sediments.
Robert Dietz and Daniel Engstrom