DISTRIBUTION OF METALS AND PAHS IN SEDIMENTS OF MULTIPLE URBAN STORMWATER CONTROL PONDS

Sediments of 20 urban and suburban costal wet detention ponds in urbanized New Hanover County, N.C. were surveyed for primary pollutant metals, polycyclic aromatic hydrocarbons (PAHs) and phosphorus (P) in summer and fall 2022. These stormwater control devices drain into the upper reaches of estuarine tidal creeks. The sampling program was undertaken because the public is often exposed to such ponds, and uses them for fishing and pet play, with unknown chemical dangers. A variety of drainage basin types sent stormwater into these ponds, which included three golf course ponds, three fire department ponds, several residential area ponds and ponds representing commercial, recreational, and waste runoff areas; a natural control pond was sampled within a nearby state park. Two types of P were analyzed for; water soluble and more tightly bound fractions extracted by the Melich 3 reagent. Analytical results were compared to various pond physical and drainage basin attributes. Total watershed size or pond age was not related to chemical contamination, but both total impervious area and percent impervious coverage were correlated with several PAHs, Cr and soluble P. Grain size was inversely related only to Cr and TP concentrations. However, organic composition of sediments was a very significant factor controlling the concentrations (i.e. retention) of TP, metals and PAHs in the detention ponds; a factor that can be controlled by pond construction,  restoration and management.

Primary Presenter: Michael Mallin, University of North Carolina - Wilmington (mallinm@uncw.edu)

Authors:

Michael Mallin, University of North Carolina Wilmington  (mallinm@uncw.edu)

Lawrence Cahoon, University of North Carolina Wilmington  (cahoon@uncw.edu)

Matthew McIver, University of North Carolina Wilmington  (mciverm@uncw.edu)

Nicholas Picha, University of North Carolina Wilmington  (pichan@uncw.edu)