Seepage patterns, pore water, and aquatic plants: hydrological and biogeochemical relationships in lakes

This study documented linkages between lakeshore seepage fluxes, pore water chemistry, and aquatic plants in several lakes of the Adirondack Mountains region of New York, USA. Three replicate stations were set up along each of four different lake shorelines. From June through September 1998 and from snowmelt in April through August 1999, seepage flux was measured with seepage meters. Throughout this time period, lake surface water and pore water chemistry were monitored weekly to biweekly. At each station, leaf tissue chemistry of the water lily Nuphar variegatum was measured once in each year. Sediment chemistry and plant abundance were also measured once in 1998. We found that pore water concentrations of base cations, iron, and zinc were related to the direction, magnitude, and variability of seepage fluxes. Concentrations of base cations, iron, and zinc were both highest and most variable where seepage was low (0 to 50mLm^–2h^–1) in contrast to being more stable where seepage was highest and variable (–608 to 612mLm^–2h^–1). Leaf tissue chemistry and plant abundance were also related to seepage patterns. N. variegatum leaves had elevated zinc content at stations with low average discharge. Knowledge of seepage patterns helped to explain spatial patterns of elevated trace metal content in both pore water and plant tissues. Our work suggests that the hydrological process of lakeshore seepage exerts important controls on lakeshore biogeochemistry.