Confirming anthropogenic influences on the major organic and inorganic constituents of rainwater in an urban area

K Chon,D H Bae,Y Kim,J Cho

doi:10.5194/dwes-8-35-2015

Abstract

Abstract. Recently, rainwater composition affected by atmospheric pollutants has been the topic of intense study in East Asia because of its adverse environmental and human health effects. In the present study, the chemical composition and organic compounds of rainwater were investigated from June to December 2012 at Gwangju in Korea. The aim of this study is to determine the seasonal variation of rainwater chemical composition and to identify possible sources of inorganic and organic compounds. The volume-weighted mean of pH ranged from 3.83 to 8.90 with an average of 5.78. Of rainwater samples, 50 % had pH values below 5.6. The volume-weighted mean concentration (VWMC) of major ions followed the order Cl− > SO42− > NH4+ > Na+ > NO3− > Ca2+ > Mg2+ > K+. The VWMC of trace metals decreased in the order Zn > Al > Fe > Mn > Pb > Cu > Ni > Cd > Cr. The VWMCs of major ions and trace metals were higher in winter than in summer. The high enrichment factors indicate that Zn, Pb, Cu, and Cd originated predominantly from anthropogenic sources. Factor analysis (principal component analysis) indicates the influence of anthropogenic pollutants, sea salt, and crustal materials on the chemical compositions of rainwater. Benzoic acids, 1H-isoindole-1,3(2H)-dione, phthalic anhydride, benzene, acetic acids, 1,2-benzenedicarboxylic acids, benzonitrile, acetaldehyde, and acetamide were the most prominent pyrolysis fragments for rainwater organic compounds identified by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that anthropogenic sources are the most important factors affecting the organic composition of rainwater in an urban area.

Highlights

Rain is an efficient scavenging process for pollutants in the air and is becoming a source of pollution to the environment (Santos et al, 2011)
Rainwater samples collected from Gwangju, Korea, during June–December 2012 were analyzed to determine the chemical composition and organic compounds present in rainwater
Even though our study period was quite short compared to other studies, we tried to present a valuable data analysis of the chemical composition and organic compounds in rainwater between summer and winter, as there are two distinct seasons with rain in Korea

Summary

Introduction

Rain is an efficient scavenging process for pollutants in the air and is becoming a source of pollution to the environment (Santos et al, 2011). The emission of SO2 and NOx from fossil fuel combustion and industrial processes has rapidly increased in East Asia due to its fast growing economy. These gases are converted into sulfuric and nitric acids before precipitating as acid rain (Lee et al, 2000; Báez et al, 2006). Automobile exhaust, and industrial emissions represent the dominant anthropogenic sources of heavy metals in rainwater (Kaya and Tuncel, 1997; Hu and Balasubarmanian, 2003; Cheng et al, 2011). Heavy metals from precipitation accumulate in the biosphere and may cause adverse human health and environmental effects (Barrie et al, 1987; Báez et al, 2007). The studies of heavy metals in rainwater have increased in many countries (Pike and Moran, 2001; Al-Momani, 2003; Báez et al, 2007)

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