Report Number: 14
Year: 1980

Marine Baseline Water Quality of the Trust Territory of the Pacific Islands

No abstract was published. A summary of the Introduction and Results follows.

The Trust Territory of the Pacific Islands (TTPI) encompasses approximately a three-million square-mile area in the western Pacific Ocean (Micronesia) and comprises over 2000 islands totaling 526 square miles of land mass. The remote nature of these islands, combined with the lack of analytical expertise on the local level, account for the sparse data base quantifying the water quality in the marine environments surrounding these islands. Water quality standards have been established for various proposed beneficial uses of the water resources in the TTPI. These standards are arbitrary to Micronesia until they are validated by the collection of water quality data in the Territory.

Islands from six districts (Marshalls – Majuro and Kwajalein Atolls; Palau – Koror; Yap Island; Truk – Moen and Dublon Islands; Ponape; and Kosrae) were selected for study to quantify existing baseline water quality. Physical, chemical, and bacteriological data were collected to provide a basis for comparison against which future environmental impacts can be assessed. Meteorological data was also collected. Specific water quality parameters quantified include temperature, salinity, turbidity, pH, dissolved oxygen, nutrients, and total and fecal coliforms. Phytoplankton growth rate limiting nutrients, minimum levels for dissolved oxygen (DO) and pH ranges were identified. Inorganic N/P mass ratios (total soluble inorganic nitrogen to total soluble inorganic orthophosphate phosphorous) were determined, and standards for total N, total P, and total and fecal coliform bacteria were also established.

Due to the lack of a representative number of samples collected at each site, reliable statistical analyses could not be performed on the individual values obtained. As a result, baseline water quality for the Territory was determined from the mean and median values. The data was normally distributed. Two-way ANOVAs (α = 0.05) were performed to compare the variances of mean island and classification values with mean values for all data.

Baseline water temperature was 29.0 ºC. Variation of arithmetic mean temperatures was greater between islands than between classes, but the difference was not statistically significant. Baseline pH was 8.10, with minimum variability between classes and statistically significant differences between islands. Mean baseline salinity was determined to be 32 o/oo. Arithmetic mean turbidity values varied significantly between TTPI classes. Median turbidity values of 0.6 and 0.8 NTU were utilized as estimates of baseline turbidity, which is affected by terrestrial inputs of silt and sediments. The median value for dissolved oxygen was 6.70 mg/L. No statistically significant differences were quantified for the mean values. Mean arithmetic mean values for total and fecal coliform bacteria ranged from 1 to 1067 per 100 mL and from <1 to 2241 per 100 mL, respectively. Three sites across the six districts violated EPB water quality standards for total coliform, while six sites violated fecal coliform standards. Baseline PO4-P levels for all waters were estimated to be 0.008 mg-P per L. Total P data were statistically different between classes. One sample from a site on Yap Island exceeded water quality standards for phosphate. Median total N concentration was estimated to be 0.14 mg-N per L. Total N data did not differ significantly between islands or classes. Mass ratios of total N/total P for all classes ranged from 10:1 to 27:1.

Peter A. Cowan
Russell N. Clayshulte