Emission characteristics and chemical composition of particulate matter emitted by typical non-road construction machinery

Abstract

According to the latest China Construction Machinery Industry Yearbook 2017, forklifts, loaders and excavators are three types of construction machinery that comprise the largest proportion of construction machinery in China. To study the emission characteristics of non-road mobile machinery, three types of non-road construction machinery used in the city were selected for testing and sampling. A Portable Emission Measurement System (PEMS) was used to obtain instantaneous exhaust emissions, and a portable particulate sampling system was used to collect PM2.5 samples from three types of construction machinery. The elements, water-soluble ions (WSIs), organic carbon (OC)/elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) were analysed. The China III standards for non-road construction machinery are stricter than the China II and China I construction machinery standards, indicating that strict regulations can help reduce PM emissions from non-road construction machinery. The results show that the fraction of the chemical components including elements, WSIs, OC/EC and PAHs to particulate matter is from 67.30% to 64.10%. The SO42−/NO3− ratio of each test vehicle is less than 1. The CE/AE values are all greater than 1, and the exhaust particles are alkaline. The estimated concentrations of secondary organic carbon (SOC) in the particulates discharged from loaders, excavators and forklifts are 3.73 mg/m3, 0.25 mg/m3 and 0.42 mg/m3, respectively, indicating the presence of secondary aerosols. The LMW-PAHs and MMW-PAHs were the major PAH species in the particulate matter, whereas a low concentration of HMW-PAHs is considered to be more harmful to human health than the other PAHs. All the PAH BaPeq values are higher than the BaP concentrations recommended by the World Health Organization. Compared with previous study, an increase in the emission standards for non-road mobile machinery can lead to a decline in pollutant emissions. In addition, the driving conditions, engine parameters, and the age of the vehicle and of non-road construction machinery, as well as the experimental methods used to study these variables, may affect the composition of exhaust emissions.