Rainfall Washoff of Spores From Concrete and Asphalt Surfaces

Abstract

The fate and transport of pollutants in urban settings is dictated by numerous complex environmental processes. Urban microclimates, short pollutant travel times, and intricate flow routing around buildings make the identification of migration pathways and the quantification of contamination on surfaces and in storm water runoff challenging. Following a wide-area pathogenic biological release, such as of Bacillus anthracis (the causative agent of anthrax), consequence management activities including sampling, mitigation, decontamination, and waste management may last for many months (D'Amelio et al., 2015; Sinclair et al., 2008). Response strategies and resource management could benefit from a better understanding of the impact of rainfall on pollutant transport, but reference studies describing washoff do not exist for biothreat agents (Mikelonis et al., 2018). Washoff is the process of removing constituents from surfaces during a period of water runoff. It is a function of many factors including rainfall intensity and/or runoff volumes or rates (Rossman & Huber, 2016; Vaze & Chiew, 2003). For the case of particles, washoff has been mechanistically evaluated through the lens of sediment transport theory, where erosion is related to a critical shear stress that can initiate movement of the particle (Vanoni, 1975). However, several aspects of urban washoff are incongruent with the bulk of work developed for sediment transport. Urban overland flow is very shallow compared to flow in rivers, impervious materials represent a large fraction of surfaces, and rainfall energy in addition to the movement of overland flow can cause particle detachment and motion. Rainfall simulators have been used for decades as the primary means to study pollutant washoff both in the laboratory and in field settings (

Evaluation of sealants to mitigate the release of per- and polyfluoroalkyl substances (PFAS) from AFFF-impacted concrete: Characterization and forecasting

“…Further, the mechanics of actual rainfall were not included in study design, and incorporating the kinetic energy, droplet size, and runoff velocity of water in future efforts could be more representative of real-world conditions ( Mikelonis et al., 2021 ). The selection of concrete depth for conducting modeling is another area of improvement.…”

Influence of wash aids on Bacillus spore removal from an asphalt parking lot using two spray-based washing methods

“…high initial concentration release into the stormwater runoff followed by exponential decay) (Charbeneau & Barrett, 1998; Water World and Environmental Resources Conference, 2004). Spraying with a high‐powered pressure washer may remove higher levels of spores than natural removal through single rain events, which are predicted to remove less than 5% of spore loading (Mikelonis et al, 2021). Percent removal by garden hose washing approximates what has been observed from simulated rainfall removal (1‐h duration, 15–115 mm/h intensity events).…”

Pollution and ecological risk assessments for heavy metals in coastal, river, and road-deposited sediments from Apia City in Upolu Island, Samoa

“…RDS is an important source of metal pollution in the surrounding rivers and coastal areas (Skorbilowicz et al, 2022;Jeong et al, 2020b;2020c). The roughness of the paved road surface, the relative abundance of RDS by particle size, and the intensity of precipitation influence the transport processes and pathways of RDS particles to the surrounding environment along with stormwater runoff (Mikelonis et al, 2021;Zhao et al, 2018;2022). Many studies have found that the heavy metal concentration in RDS increases with decreasing particle size (Jeong and Ra, 2022a;Logiewa et al, 2020).…”