Fig. 5. (a) Wastewater as a percentage of total N load as calculated with the N-loading model of Valiela et al. (1997)(2000) vs. particulate organic matter (POM) ¹⁵N for six sites of present study, three sites of McClelland et al. (1997) and McClelland and Valiela (1998), and six Narragansett Bay estuaries. (b) Mean annual water-column dissolved inorganic nitrogen (DIN) concentrations vs. POM ¹⁵N for sites in Cape Cod (CC), New Hampshire (NH), Florida (FL), U.S. West Coast (WC), and Brazil (BR). ¹⁵N values are means of all sampling dates, and error bars represent standard error.