MONITORING OF BA, MN, CU AND NI DURING ESTUARINE MIXING

Practical clean analytical methods for the monitoring of Ba, Mn, Cu an d Ni in estuarine waters with salinity ranging from near zero to about 32 parts per thousand are reported. Three longitudinal surveys were c onducted on the levels of Ba, Mn, Cu and Ni for Selangor River and Kla ng River from the upper estuary freshwater points to the river mouth. In addition, monitoring of dissolved Ba were carried out at a fixed es tuarine station of the Selangor River over the daily flood-ebb tidal c ycles for a neap tide and two spring tide occassions. The longitudinal surveys show both input and removal of the trace metals monitored dur ing estuarine mixing. The fixed station study shows that the concentra tions of dissolved Ba vary in the range from 3.4 to 5.7 mu g/L for nea p tide samples, whereas concentrations ranging from 6 to 120 mu g/L we re observed for spring tide samples. Variations of the trace metal con centrations over the daily tidal cycles and sample standing were depen dent on the water salinity, pH, dissolved oxygen and suspended solids levels.