Distribution of Arsenic in the Sediments and Biota of Hilo Bay, Hawaii

Abstract

Sediment samples collected from the Waiakea Mill Pond, Wailoa River, and Hilo Bay were analyzed for arsenic. Arsenic was detectable in 10of II sediment samples, and ranged in concentration from 2 to 715 ppm. Two species of plant and seven species of animal were collected from the Waiakea Mill Pond and analyzed for arsenic. No arsenic was detected in the plants, whereas four of the seven animal species had arsenic concentrations ranging from a trace to 1.3ppm. Sediments of the Wailoa River estuary have much higher concentrations of' arsenic than those of Hilo Bay, indicating that most arsenic is located near the original source of pollution, a factory that once operated on the shores of the Waiakea Mill Pond. Much of the arsenic is found in anaerobic regions of the sediment where it has been relatively undisturbed by biological activity. The low levels of arsenic in the biota of the estuary suggest that there is little remineralization of the region's arsenic and that it is trapped in anaerobic sediment layers.