Paudel, B.; Weston, N.; O'Connor, J.; Sutter, L., and Velinsky, D., 2017. Phosphorus dynamics in the water column and sediments of Barnegat Bay, New Jersey. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay-Little Egg Harbor, New Jersey.
Phosphorus (P) loadings are higher in northern Barnegat Bay, New Jersey, relative to southern Bay, whereas ambient dissolved P is higher in the southern part of the Bay. This study investigated the mechanism for higher water-column P in the southern part of the Bay relative to the northern Bay. The authors hypothesized that sediments may be the source of P to the water column in the southern Bay. Water-column samples and sediment cores were collected from 20 stations along the N-S gradient of the Bay on three dates (spring, summer, and fall) in 2014–15. Benthic sediment P flux experiments were conducted under oxic and anoxic conditions. Phosphorus was sequentially extracted from sediments into five operationally defined fractions: loosely sorbed P, iron bound P, inorganic bound P, calcium bound P, and organic bound P. The results confirmed that soluble reactive P (SRP) was higher in the southern Bay (29 to 53 μgP/L) compared to the northern Bay (below detection to 21.2 μgP/L). Iron and inorganic bound P were the highest fractions of sediment P. Sediment total P was higher in the southern Bay stations. Benthic flux measurements indicated that sedimentary release of SRP was negligible, and no N-S gradient of P release occurred. Rather than a source of SRP to the water, the sediments were identified as a sink for P in the southern stations. The higher chlorophyll-a in the northern vs. southern Bay and lower concentration of SRP and NO2 3 in the northern vs. southern Bay indicate that hydrodynamics and water-column primary productivity, rather than sediment P dynamics, are the major drivers of the observed patterns of water-column nutrients in Barnegat Bay.