Atmospheric Nitrogen Deposition to the New Jersey Coastal Waters and Its Implications

In situ measurements of atmospheric NO3 and NH4 þ at Sandy Hook on the northern New Jersey (USA) coast and at Tuckerton on the southern New Jersey coast reveal significant temporal and spatial variations of these inorganic N constituents. The mean concentration of NO3 in precipitation was higher at Sandy Hook (44.6 lmol/L) than at Tuckerton (29.1 lmol/L). The mean concentration of NH4 þ in precipitation exhibited a similar pattern, being higher at Sandy Hook (26.3 lmol/L) than at Tuckerton (18.3 lmol/L). Aerosol NO3 and NH4 þ concentrations at Sandy Hook were also higher than those at Tuckerton. On an annual basis, the total atmospheric deposition of NO3 was estimated to be 51.1 mmol m 2 yr 1 at Sandy Hook and 32.9 mmol m 2 yr 1 at Tuckerton. For NH4, the total atmospheric deposition was 32.8 mmol m 2 yr 1 at Sandy Hook and 20.3 mmol m 2 yr 1 at Tuckerton. Wet deposition accounted for up to 89% of the total NO3 deposition and 76–91% of the total NH4 þ deposition on the New Jersey coast. By comparison, NO3 and NH4 þ concentrations are relatively low in estuarine waters of New Jersey. The annual mean NO3 concentrations recorded in surface waters of the Mullica River–Great Bay Estuary near the Tuckerton atmospheric site during the 2002–2004 period were as follows: 12.1 lmol/L for the upper estuary, 4.5 lmol/L for the mid-estuary, 2.5 lmol/L for the lower estuary, and 1.2 lmol/L for the bay inlet area. The annual mean NH4 þ concentrations in these waters were as follows: 1.5 lmol/L for the upper estuary, 3.8 lmol/L for the mid-estuary, 3.8 lmol/L for the lower estuary, and 2.4 lmol/L for the bay inlet area. In the Barnegat Bay–Little Egg Harbor Estuary, the mean concentrations of NO3 plus NO2 were ,4 lmol/L. In this system, atmospheric deposition accounts for ;39% of the total N load. These results suggest that atmospheric deposition appears to be an important pathway of new N inputs to New Jersey coastal waters and a potentially significant N enrichment source for biotic production.