Gary Denton

Gary Denton, Ph.D
Prof. Environmental Toxicology

Phone: 671-735-2690 (fax 734-8890) (GMT+10 hrs)
gdenton(weriguam)uguam.uog.edu?subject=Faculty - WeriGuam.org

Ongoing Projects

Mercury Contamination in Garapan Lagoon, Saipan: An Evaluation of Potential Drainage Pathways and Impact on Fisheries Resources

This project was initiated in response to relatively high levels of mercury being detected in fish from the Micro Beach area in the northern section of Garapan Lagoon, Saipan. Soil from drainage basins within the Garapan area and sediments from the coastal belt are currently being analyzed in an attempt to locate possible terrestrial source of contamination and identify drainage pathways into the lagoon. Biotic representatives from this popular fishing spot are also being considered. Potential sources of mercury contamination so far identified include the local hospital and a newspaper printing press. Soil from a drainage ditch in the grounds of the former site contained in excess of 1200 ng Hg/g dry weight of soil -- approximately 40 times higher than normal background levels. Expected completion date: Summer 2008. (Funding source: US Geological Survey).

 

Persistent Contaminants in Popular Table Fish from Tanapag Lagoon, Saipan

PCB, mercury and arsenic are being screened in popular table fish from Tanapag Lagoon, Saipan, as part of an ongoing pollution contamination and assessment program for this area. Specimens are being analyzed from nearshore and offshore locations within the lagoon in order to identify and delineate terrestrial source of contamination. Species selected for study include those with restricted foraging ranges as well as those that are more roving in their feeding habits. To date, some 360 fish representing 65 different species from various trophic levels have been analyzed for mercury and arsenic. PCB analysis is currently underway. Mercury and arsenic levels detected in the axial muscle of samples analyzed range from 0.006-0.616 µg/g wet weight and 0.027-36.13 µg/g wet weight respectively. Total PCB concentrations (sum of 20 congeners) encountered in axial muscle of fish so far examined range from 0.47-46.4 ng/g wet weight. Data evaluations of all three contaminants will include a human health risk assessment. Expected completion date: Summer 2008. (Funding source: US Geological Survey)

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Heavy Metals in Biotic Components from Tanapag Lagoon, Saipan

The study is focusing on dominant ecological representatives that inhabit the shallow nearshore waters of Tanapag Lagoon, Saipan, with emphasis on groups with high bioindicator potential that are either sessile or are restricted in their movement e.g., algae, seagrass, seacucumbers, bivalves and juvenile fish. Representatives of each are currently being collected from intertidal sites along the entire length of the lagoon. Most of these sites were impacted by land-based sources of contamination of one sort or another. Metals of interest include arsenic, cadmium, chromium, copper, lead, mercury, nickel, silver and zinc. The data are being evaluated with reference to similar and related species collected from tropical environments elsewhere in the world. Expected completion date: Summer 2008. (Funding source: US Geological Survey)

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