Influence of Seawater to the River Water Quality in Kalibuntung Estuary Southeastern Coast of Surabaya City Indonesia

Abstract

This study reports distribution of water quality parameters, i.e. salinity, nitrite, nitrate, and phosphate of the Kalibuntung estuary in the southeastern Surabaya coastal area. The study was conducted over 34 sampling points in the river channel, river mouth, and in the coastal water of the Kalibuntung estuary. The result shows that the minimum salinity of (2-4 ppt) reached 3,000 m far from the coastline to upper strem. The maximum salinity of 28.60 ppt found in the coastal water, about 1,000 m seaward from coastline. Based on the numerical modeling analyses, distribution of salinity followed the water movement of eeb-flood currents cycles due to tidal fluctuation. The result obviously revealed that during flood current, water mass from the sea moves to the upper river, on the other hand, during eeb current more volume of river water flows to the sea. It is indicated by salinity values in the river mouth, which reached 27 ppt during high tide and < 20 ppt during low tide. Concentration of ammonia ranging from 0.42 mg/l in the lower part close to the river mouth, up to 6.13 mg/l in the uppermost of the river. This indicated that the river is heavily polluted by organic waste. Concentration of phosphate range from 0.06 to 0.43 mg/l. Its concentration decrease seaward, it is distributed to a distance of 3,000 m fom the river mouth. The river water of Kalibuntung estuary is not permitted to be used as a drinking water, and also it is not feasible for coastal aquaculture. Only in the lower part of the study area where it close to the rivermouth, its water can be used as a source of the coastal aquaculture. This research also found that the river water of the study area has already heavily polluted by organic waste, which it might come from domestic waste, agriculture or fertilizer for fishpond, or industrial organic waste.

Benthic macroinvertebrates as bioindicators to detect the level of water pollution in the upstream segment of Brantas River Watershed in Malang, East Java, Indonesia

“…The presence of ammonia in water can be attributed to the decomposition of inorganic and organic nitrogen compounds, including protein and urea (Putro et al 2021). According to Wahyudi et al (2017), the typical concentration of ammonia in river waters is less than 0.5 mg/L. In unpolluted waters, the ammonia concentration is below 1 mg/L, whereas in polluted waterways, it can exceed 10 mg/L.…”