Shrnutí

Popis

Water quality at 10 recreational beaches in Mamala Bay and in the nearshore ocean were monitored over a period of 12 months in 1993-1994 to determine the impact of sewage discharges and non-point source pollution on conditions in the bay. Measurements included temperature, salinity, nutrients and other parameters. The data were collected under direction of Dr. Edward Laws of the University of Hawaii for the Mamala Bay Study, Ecosystem Response Study, MB-9. Samples were collected by wading into the water and filling a 20-liter carboy with water from just below the surface in water about one meter deep. Samples were collected at the ten beaches on a monthly basis from August 1993 to July 1994. The samples were collected from just below the surface in acid-cleaned 20-liter plastic carboys at a distance from the shoreline where the water column was one meter deep. The temperature of the water was recorded immediately using a thermometer calibrated to 0.1 oC and the conductivity measured with an Extech Oyster conductivity meter. Upon return to the laboratory, aliquots of the water were filtered through GF/F filters for further analysis. The filtrates were used to determine inorganic nutrient concentrations as previously described. Samples for PC and PN analysis were collected on precombusted GF/F filters and processed as described above. Samples for chl a and carotenoid pigment analysis were collected on GF/F filters and placed in liquid nitrogen prior to extraction. The pigments were extracted by placing the filters in approximately 5 ml of acetone for 12 h. The filters were then ground using a Wheaton tissue grinder and the filter residue removed by centrifugation as described in Strickland and Parsons (1972). The extracted pigment concentrations were then determined on a Varian 5000 high performance liquid chromatograph (HPLC) as described by Laws et al. (1990).