Abstract:
The spatial and temporal variations of dissolved inorganic nutrient concentrations in the Bangpakong estuary were studied from April 1998-March 1999, during the wet (May-October) and dry (November-April) seasons. The concentration range of phosphate, ammonia, nitrite, nitrate and silicate were 0.28 -3.45, 2.46-19.80, 0.04-7.32, 0-50.44 and 0.90-53.30 uM respectively. Chlorophyll a, b and c concentration ranged between 3.61-92.57, 0-7395 and 0.94 -37.86 mg/m3 respectively. Phophate and nitrite concentrations showed no trend with temporal variation. In the wet season, phophate and nitrite concentration were similar to the dry season, whereas other nutrients showed temporal trends. In the wet season ammonia, nitrate and silicate were higher than in the dry season. Nitrite, nitrate and silicate concentration also showed spatial variation. In the inner estuary stations (station 1-3), nitrite, nitrate and silicate were higher than the outer stations (station 6-8), but phophate and ammonia showed no spatial variation. Chorophill concentrations dhowed temporal variation but no spatial variation. In the wet season, chorophyll a, b and c were higher than in the dry season. The inner estuary stations values for chlorophyll a, b and c were close the values of the outer estuary stations. The relation of dissolved inorganic nutrient, chlorophyll content and water quality in the Bangpakong Estuary is as follows. Phosphate, nitrite, nitrate and silicate had a positive relation to suspended solids and a negative relation to pH, while ammonia had a negative relation to pH. Ammonia, nitrate and silicate had negative relation to salinity. Chlorophyll a showed a positive relation to nitrate concentration and dissolved oxygen content.