Acidic Wet Deposition in Bandung City Indonesia

¹ Environmental Engineering Doctoral Program, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung 40132.
² Air and Waste Management Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung 40132.
³ Analytical Chemistry Research Group, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung 40132.
⁴ Environmental Technology and Management Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung 40132.

^* Corresponding author: driejana@tl.itb.ac.id

Abstract

Acidic deposition (acid rain) has been known to cause negative impact to environment. Measurement of rain chemical composition was done in March to August 2016 to investigate temporal variation of atmospheric deposition in Bandung City. Rainwater samples are collected at four sampling sites. The chemical properties of the rain determined were pH and ionic concentrations of SO₄²-, NO₃-, Cl^-, Ca²⁺, Mg²⁺, Na⁺, K⁺ and NH₄⁺. The rainwater was typically acidic with the range of mean pH between 5.29 – 5.56 and mean electric conductivity value range between 16.37 – 19.96 μS/cm. Temporal variation showed higher SO₄²⁺, NO₃⁺ and NH₄⁺ concentration in August when rainfalls were the lowest (214.88 mm). Similar temporal variation for the mean pH (5.98) and electric conductivity (25.36 μS/cm) in August. Ca²⁺ highest concentration was observed in June. Generally, the the major component of precipitation chemistry were SO₄^2- and NO₃^-, Ca⁺ and NH₄⁺, for anion and cations, respectively. The largest proportions of the total anions in all sampling sites was SO₄^2- ranged from 32% (Lembang) to 37% (Buah Batu) followed by NO₃^- (13 – 15%) and and Cl^- (4 – 7%). For cations, NH₄⁺ dominated with proportion ranged between 21 – 27% and subsequently Ca²⁺ (13 – 19%) and followed by Na⁺, Mg⁺, K⁺ and H⁺. The Neutralizing Factor (NF) results reveal that Ca²⁺ and NH₄⁺ are the dominant neutralization substances in the rainwater. However it should be noted that reduced nitrogen (NH₄⁺) act as mobile nitrogen that further will acidify the environment, particularly to soil ecosystem downstreams.