Uncertainties in the assessment of volatile hydrocarbon pollution of urban stormwater

Abstract

Assessing the risk to human health posed by stormwater pollutants is critical, because stormwater is considered as an alternative water resource to mitigate water deficiencies, which is becoming increasingly common around the world. In this context, hydrocarbons with different volatility that are common in the urban environments pose significant human and ecosystems health risks resulting from wash-off into receiving waters during rainfall events. Effective mitigation strategies require reliable stormwater quality modelling approaches incorporated with accurate assessment of uncertainty in stormwater quality predictions. This study employed Bayesian Network modelling to investigate how anthropogenic and climatic factors influence the build-up of particle-bound hydrocarbons, with specific focus on volatile hydrocarbons, and thereby assessed the uncertainty inherent to their build-up process. The study found that volatile hydrocarbons build-up rapidly in the early stage of the antecedent dry period, and volatility plays a key role in the build-up of these pollutants. Significant differences in the temporal variations in build-up could be observed between different seasons. Further, season specific conditions and physico-chemical characteristics of particulates were found to influence the behaviour of volatile hydrocarbons during build-up.