Pesatnya pertumbuhan penduduk, meningkatnya arus transportasi, dan industri yang ada di Kota Padang serta efek termal inverse dapat memicu pencemaran udara yang menyebabkan terjadinya hujan asam di Kota Padang. penelitian ini bertujuan 1. menganalisis kandungan Nitrat, Sulfat dan pH air hujan, 2. pengaruh intensitas hujan terhadap kadar asam air hujan di Kota Padang, 3. Menganalisis pengaruh suhu udara, kelembaban udara, tekanan udara, arah dan kecepatan angin terhadap kadar asam air hujan di Kota Padang. Metode penelitian yang digunakan adalah pengukuran lapangan dan uji laboratorium. Pengukuran lapangan yang dilakukan antara lain intensitas hujan, pH, suhu, kelembaban, tekanan udara, arah dan kecepatan angin, sedangkan uji laboratorium yang dilakukan antara lain pengukuran kadar Sulfat dan Nitrat yang terkandung dalam air hujan. Pengambilan sampel air hujan menggunakan teknik Purposive yang ditampilkan dalam poligon Thiessen. Analisis data meliputi analisis data iklim, analisis intensitas hujan, analisis regresi linear ganda, analisis keruangan dan analisis deskriptif. Hasil uji laboratorium menunjukkan bahwa kandungan Sulfat dan Nitrat dalam air hujan di Kota Padang masih di bawah ambang baku mutu air bersih NO: 416/MENKES/PER/IX/1990 yaitu 400 mg/l untuk Sulfat dan 10 mg/l untuk Nitrat. Pengaruh intensitas hujan terhadap kadar asam air hujan berbanding terbalik terhadap kadar Sulfat dan Nitrat dan berbanding lurus dengan pH. Hasil uji validasi dan kelayakan persamaan regresi linear ganda hubungan antara kadar Sulfat, Nitrat dan pH dengan variabel bebas sebai faktor terpilih yang ditampilkan dalam uji asumsi klasik menunjukkan bahwa Sulfat dan pH signifikan, sedangkan Nitrat tidak signifikan.

The fast growth of population, the increased flow of transportation, industry spread in Padang Municipality, and thermal inverse effect can trigger air pollution leading to acid rain in the municipality. The aims of this study are to analyze the nitrate, sulfur and pH contents of rain water and to analyze the effect of rain intensity, air temperature, air pressure, and wind direction and speed on the acidity of rain water in Padang Municipality. The study was conducted using a field measurement and a laboratory test. The field measurement was done on rain intensity, pH, temperature, moisture, air pressure, and wind direction and speed, while the laboratory test was carried out on sulphate and nitrate contained in rain water. The sample of rain water was collected by a purposive sampling technique as displayed in Thiessen polygon. The sample of rain water was collected in ten times of sampling in six regions of Thiessen polygon in Padang Municipality. The data collected were analyzed by climate data analysis, rain intensity analysis, multiple linier regression analysis, spatial analysis, and descriptive analysis. The results of the laboratory test showed that sulphate and nitrate contents in rain water in Padang Municipality was still under the threshold of clean water quality No. 416/MENKES/PER/IX/1990, i.e. 400 mg/l for sulphate and 10 mg/l for nitrate. The effect of rain intensity on the acidity of rain water was inversely proportional to sulphate and nitrate contents and directly proportional to pH. The results of validation test and multiple linear regression analysis about the effect of sulphate, nitrate, and pH contents and independent variable as the selected factor displayed in classic assumption test showed that sulphate and pH contents had a significant effect, while nitrate content had no significant effect.

Kata Kunci : Kadar Asam, hujan, Sulfat, Nitrat, pH