Water Resources Research Act Program

Details for Project ID 2015GU285B

Impact of Multiple Mercury Sources on Edible Quality of Fish from American Memorial Park Nearshore Waters, Saipan, CNMI

Institute: Guam
Year Established: 2015 Start Date: 2015-03-01 End Date: 2016-02-29
Total Federal Funds: $38,568 Total Non-Federal Funds: Not available

Principal Investigators: Gary Denton

Abstract: The massive clean-up of Saipan at the end of WWII gave rise to unprecedented waste disposal problems that linger on the island to this day. The disposal of munitions, for example, was largely solved by dumping and often involved detonation attempts by fire in natural gulleys and shallow pits dug in the ground. This disposal practice was not particularly effective and, for the most part, only added to the environmental mercury problem created earlier by the heavy shelling that accompanied the US invasion. The first hint of potentially wide-spread mercury contamination on Saipan emerged in 2007 when an independent research team reported frequent and occasionally high mercury detections in stormwater discharged into the southern half of the lagoon (Environ Inc. 2007). These findings were especially noteworthy because mercury is rarely encountered in urban runoff (USEPA 1983). Shortly afterwards, WERI researchers noted unusual mercury distribution patterns in sediments from the same region of the lagoon and suggested that inputs washed in from land-based sources were superimposed upon a scattering of mercury contamination emanating from within the lagoon itself (Denton et al. in 2014). Since mercury was used extensively in WWII (as mercury switches in projectiles and rockets, and as the primary explosive, mercury fulminate, in primers and detonators of artillery shells and percussion caps of bullets) it was postulated that pockets of mercury contamination associated with exploding WWII ordnance and lost ammunition had been created along the coastal belt and in the lagoon. More recent evidence supports this contention. Studies are underway to determine the full impact of this contamination on fisheries in the southern half of Saipan Lagoon where the fighting between US and Japanese troops was particularly fierce. The project described herein proposes to extend this fish monitoring program to nearshore water adjacent to the American Memorial Park (AMME). This beautiful park commemorates American soldiers who lost their lives during the Saipan campaign. Sadly the parks picturesque landscape belies the history of its wartime past and in 2004, hundreds of unexploded ordnance were unearthed during the construction of the Visitor Center car park. A magnetometer sweep suggested hundreds more were buried outside of the construction area (AMPRO 2005). Around the same time, unusually high mercury levels were encountered in fish from a reef complex a little over 500m NW of the parks western border (Denton et al. 2010). A connection between these findings and mercury sources in AMME was not considered until moderate mercury contamination in surface soils from within the park grounds was recently discovered. The aqueous transported of mercury from the park into the coastal belt is not difficult to envisage given the hydrological dynamics of the area (Perreault 2007). The proposed survey will thus focus on fish with restricted foraging ranges from nearshore sites adjacent to AMME between Micro Reef and the SW face of Puerto Rico Dump. Parallel sediment sampling will also occur along transects extending perpendicular to the shore in this region to determination mercury concentration gradients associated with contributions from land-based sources. The primary objectives of the study are to: a) identify and delineate hitherto unknown sources of mercury contamination within the study area; b) determine the collective impact these sources on the edible quality of fish; c) evaluate potential health risks associated with unrestricted consumption of fish from impacted areas; d) provide additional data to assist with the identification and delineation of areas of contaminant enrichment within Saipan Lagoon, and e) enhance ongoing marine monitoring, management and mitigation strategies for Saipans coastal waters.