The Challenge of Vehicular Emission and Atmospheric Deposition: From Air to Water

摘要

On a global scale, atmospheric deposition is a serious issue that has impacts on chemistry, physics and biology of the atmosphere. Combustion of fossil fuels and the resultant vehicular emissions release several harmful components, which plays an important role in atmospheric deposition. The harmful components from vehicular emission include the discharge of gases such as carbon monoxide (CO), oxides of nitrogen, sulphur dioxide, etc. and particulate emissions. Such emissions are also associated with different inorganic and organic pollutants (heavy metals (HMs) such as Pb, Cu, Zn etc, organic pollutants such as hydrocarbons etc). Depending on the type of vehicle and the fossil fuel used, the number of released compounds and the pollution load varies. The emitted vehicular gasses and the particulates retained in the atmosphere (for a certain time period) can possibly drift over long distances. The weight of the particulates, its size, wind, temperature, and humidity can determine the retention time of particulates in the atmosphere, but ultimately, these particulates end up in deposition. The particulates deposit with rainfall, snow fall and fog. Suspended particles can also deposit directly in the dry form. Through direct and indirect deposition, atmospheric particulates can end up in urban waters via stormwater and thereby influencing water quality of receiving water bodies. Hence, the monitoring and quantification of pollutants present in the atmosphere, atmospheric precipitation and deposition is an urgent necessity. This chapter discusses the effects of vehicular demography on emission including gaseous and particulate emissions, their quantities, their distribution, and their impacts on the water environment. To date, several mechanisms and bio-monitoring methods (Lichen, mosses) have been developed to detect and quantify such deposition and this chapter relates the extent of pollutants in the air to that of surface water.