Impact of WWII dumpsites on Saipan (CNMI): heavy metal status of soils and sediments

A number of dumpsites occur on the island of Saipan and in the surrounding coastal waters. Many of these sites date back to the immediate post WWII clean-up period and contain a variety of wartime wastes. Metallic debris is generally the most visible waste material and commonly includes bomb fragments, artillery shells, bullets, and other military hardware. In this investigation, we examined the heavy metal status of soils from around several of these dumpsites and in any obvious drainage pathways leading from them to the coast. Sediments were also taken for analysis from a number of coastal discharge points and three submerged sites. Metal enrichment was evident for one or more elements in deposits from two of the three submerged sites and 24 of the 32 land-based sites visited. Copper, Pb, and Zn were the most commonly encountered contaminant metals with levels well in excess of 1000 μg/g -1 in several instances. Elevated Hg and Cd concentrations were also relatively widespread throughout the study area although levels of each element seldom exceeded 1.0 and 10.0 μg/g -1 , respectively. Silver, another element of toxicological concern, was only occasionally detected despite registering a high of 42 μg/g -1 at one particular site. The metal data were weighed against established benchmarks formulated for the protection of human and ecological health. Implications of the findings and issues of primary concern are briefly addressed.