Atmospheric Arsenic Deposition in Chiayi County in Southern Taiwan

Long-Full Lin,Chia-Wei Lin,Lin-Chi Wang,Guo-Ping Chang-Chien,John Kennedy Mwangi,Sheng-Lun Lin,Yi-Ming Lin,Shu Hsien Wu

doi:10.4209/aaqr.2012.11.0315

Abstract

Although arsenic contamination of underground water in southern Taiwan is well known, few studies examine atmospheric arsenic deposition in this area, which might be the major source of such pollution to the soil, water, and even underground water. This research focused on the atmospheric arsenic concentration, dry and wet depositions, and the As distribution around Chiayi County, located in the south of Taiwan. Eight sampling sites are used, both upwind and downwind of an area with heavy industrial and human activities. All samples were collected by a PS-1 high volume sampler at each site, pretreated by a digestion process, and further analyzed with an ICP-MS. The results show that the arsenic deposition flux ranged from 65.0 to 473 μg/m2-month in Chiayi County. This deposition flux has no significant seasonal variation, based on the multiple trend results obtained from pooling the dry and wet deposition data. The average dry deposition flux of As ranged from 34 to 161 μg/m2-month during the sampling year, and had the opposite trend to the wind speed. Additionally, the correlations between atmospheric arsenic concentration and PM levels were significant, supported by the low p-value (< 0.01) at a 99% confidence level. Meanwhile, the highly linear correlation between As and PM concentrations was also evaluated. The amount of precipitation was statistically correlated to the wet deposition flux (11.3–414 μg/m2-month with a p-value = 2 × 10–7 and r-value = 0.9306. Furthermore, the composition of the As mass concentrations in ambient air were dominated by As (V) in both fall (66.4%) and winter (68.9%). According to the GIS spatial analysis of the As concentration in the dry season, from October to March, the As contribution of local emissions were not significant. Consequently, this study indicates that the atmospheric As around Chiayi County might be sourced from the upwind northern area, and mainly deposited through wet scavenging.

Highlights

The level of atmospheric arsenic (As) level and its deposition are issues of public concern, due their adverse effects on both human health and the environment (Contreras et al, 2009; Kang et al, 2011; Shi et al, 2012)
Throughout the related high temperature processes, some arsenic compounds are adsorbed on volcanic ash and deposited to the ground, while the others remain in atmospheric aerosols, and these are subject to longrange transportation in the troposphere (Thomaidis et al, 2003; Wang et al, 2010; Chen et al, 2012; Fang et al, 2012a)
The seasonal variation of total As deposition flux was not significant, and this was because two different mechanisms were pooled together in this work

Summary

Introduction

The level of atmospheric arsenic (As) level and its deposition are issues of public concern, due their adverse effects on both human health and the environment (Contreras et al, 2009; Kang et al, 2011; Shi et al, 2012). Arsenic compounds are emitted to the atmospheric environment from both natural sources and human activities, and further contained in suspended aerosol in the atmosphere (Lopez-Anton et al, 2006; Kang et al, 2011). Throughout the related high temperature processes, some arsenic compounds are adsorbed on volcanic ash and deposited to the ground, while the others remain in atmospheric aerosols, and these are subject to longrange transportation in the troposphere (Thomaidis et al, 2003; Wang et al, 2010; Chen et al, 2012; Fang et al, 2012a). The burning of firework during the special festival in Asian culture was reported as one of the main sources of trace metal, including As (Do et al, 2012)

Methods

Results

Conclusion