Groundwater nitrogen concentration changes in an urbanized area of Indonesia over ten years period

Nitrogen in groundwater poses environmental concerns in Bandung Region, Indonesia, due to natural and anthropogenic factors. The predominant component of the region's aquifer is high-hydraulic-conductivity volcanic rock, one of the natural vital factors that make the aquifer vulnerable to contamination. Another factor is urbanization which has been reported to be an adverse effect of high nitrogen levels in the groundwater, particularly the unconfined system. This study's objective was to evaluate urbanization's impact on dissolved inorganic nitrogen concentrations over a 10-year period, which had not been explained by previous research. The evaluation focused on land-use changes in the southern part of the Bandung Region and their relation to dissolved inorganic nitrogen (DIN) in unconfined groundwater. A total of 88 samples were collected in 2009, 2015, and 2018 from three types of land-use: residential, plantations, and paddy fields. From 2009 to 2018, land use changes were visible, with an 8% and 6% increase in urban settlements and rice fields, respectively, and a 15% reduction in plantations. Furthermore, over a decade, agricultural and rice fields substantially impacted the NO3- levels, contributing approximately 13.2 mg/L and 9.9 mg/L, respectively. In the meantime, the settlement area significantly contributed to the 3.25 mg/L increase in the NH4+ levels.