Aluminum Concentrations In The Mullica River-Great Bay Estuary, New Jersey

Abstract

Dissolved aluminum in filtered water (0.45 µm) from the Mullica River-Great Bay Estuary, New Jersey, and from six northeastern United States rivers was analyzed by a fluorometric method using Manganon as the fluorometric reagent. The aluminum content of the six rivers sampled ranged from 4 to 42 µg/1, with an average of 15 µg/1 (corrected for discharge). During the summer and fall of 1977, the aluminum content of the Mullica River averaged approximately 35 µg/1. The aluminum content of the water during the winter and spring of 1978 was approximately six times that of the previous summer and fall, with a mid-winter high of 237 µg/1. In Great Bay Estuary, aluminum exhibited definite non-conservative behavior, with more than 80% removal of the aluminum by salinities of less than 10°/oo. This behavior is similar to that previously observed for iron in this estuary (Coonley et al., 1971). The aluminum concentration appears to be controlled by the solubility of crystalline gibbsite. The estimated flux of dissolved aluminum from the estuary into the ocean is less than 5 µg/1. Assuming these are representative data, an oceanic residence time for aluminum is calculated to be 25,000 years.