Spatial distribution of arsenic residues from historic application to sugarcane on the Hamakua Coast, Hawaiʻi

Abstract

Arsenic based herbicides were applied from 1913-1945 on sugarcane plantations along the Hamakua Coast and As remains prevalent both on and off these lands. This research presents an investigation of the spatial distribution from highly contaminated topsoil (0-30 cm) of Hawaiian Andisols from the Hamakua Coast of the Island of Hawaiʻi. Arsenic concentrations were found to be elevated (216 ± 20 mg kg-1) in comparison to the background levels in Andisols (<20 mg kg-1). Andisols of this study included soil series Onomea, Akaka, Kaiwiki, Hilo, and O'okala. As spiked solutions of 58 mg L-1 were applied to all soils and <0.5 mg L-1 As remained in solution after equilibrium. There was a relationship between flow accumulation and As on a localized scale, not a watershed scale. Therefore, most of the As was in the solid phase and elevated As concentrations may be found in areas of high flow accumulation.