ATMOSPHERIC NITROGEN DEPOSITION TO THE NEW JERSEY COASTAL WATERS AND ITS IMPLICATIONS

In situ measurements of atmospheric NO 3 − and NH 4 + 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 NO 3 − in precipitation was higher at Sandy Hook (44.6 μmol/L) than at Tuckerton (29.1 μmol/L). The mean concentration of NH 4 + in precipitation exhibited a similar pattern, being higher at Sandy Hook (26.3 μmol/L) than at Tuckerton (18.3 μmol/L). Aerosol NO 3 − and NH 4 + concentrations at Sandy Hook were also higher than those at Tuckerton. On an annual basis, the total atmospheric deposition of NO 3 − 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 NH 4 + , 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 NO 3 − deposition and 76–91% of the total NH 4 + deposition on the New Jersey coast. By comparison, NO 3 − and NH 4 + concentrations are relatively low in estuarine waters of New Jersey. The annual mean NO 3 − 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 μmol/L for the upper estuary, 4.5 μmol/L for the mid‐estuary, 2.5 μmol/L for the lower estuary, and 1.2 μmol/L for the bay inlet area. The annual mean NH 4 + concentrations in these waters were as follows: 1.5 μmol/L for the upper estuary, 3.8 μmol/L for the mid‐estuary, 3.8 μmol/L for the lower estuary, and 2.4 μmol/L for the bay inlet area. In the Barnegat Bay–Little Egg Harbor Estuary, the mean concentrations of NO 3 − plus NO 2 − were <4 μmol/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.