Seasonal Variation of Dissolved Inorganic Nitrogen in Bangpakong Watersheds in 2016

Abstract

This study aimed at investigating seasonal variations of dissolved inorganic nitrogen in Bangpakong River and its estuary in 2016. Water samples from the surface and the bottom from 16 stations were taken. The results showed that ammonia, nitrite and nitrate were 9.22-75.78 µg-at N/L, 0.03-20.69 µg-at N/L and 0.11-100.39 µg-at N/L, respectively. All these dissolved inorganic nitrogens varied seasonally with the greatest change occurring during the transition from dry season to wet season in July. Notably, ammonia in surface water decreased and was likely transformed into other N species during dry season in April and wet season in September, while nitrate in bottom water might be reduced to nitrite and ammonia by bacterial activities. The statistical analyses confirmed that the dissolved inorganic nitrogen concentrations differed significantly between wet and dry seasons (p<0.05).