Alkylated Polycyclic Aromatic Compounds in Road Runoff Are an Environmental Risk and Should Be Included in Future Investigations

Tracking the history of polycyclic aromatic compounds in London through a River Thames sediment core and ultrahigh resolution mass spectrometry

Polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and heteroatom-containing analogues, constitute an important environmental contaminant class. For decades, limited numbers of priority PAHs have been routinely targeted in pollution investigations, however, there is growing awareness for the potential occurrence of thousands of PACs in the environment. In this study, untargeted Fourier transform ion cyclotron resonance mass spectrometry was used for the molecular characterisation of PACs in a sediment core from Chiswick Ait, in the River Thames, London, UK. Using complex mixture analysis approaches, including aromaticity index calculations, the number of molecular PAC components was determined for eight core depths, extending back to the 1930s. A maximum of 1676 molecular compositions representing PACs was detected at the depth corresponding to the 1950s, and a decline in PAC numbers was observed up the core. A case linking the PACs to London's coal consumption history is presented, alongside other possible sources, with some data features indicating pyrogenic origins. The overall core profile trend in PAC components, including compounds with oxygen, sulfur, nitrogen, and chlorine atoms, is shown to broadly correspond to the 16 priority PAH concentration profile trend previously determined for this core. These findings have implications for other industry-impacted environments.

High levels of tire wear particles in soils along low traffic roads

Traffic pollution has been linked to high levels of metals and organic contaminants in road-side soils, largely due to abrasion of tires, brake pads and the road surface. Although several studies have demonstrated correlations between different pollutants and various traffic variables, they mainly focused on roads with medium to high traffic density (>30,000 vehicles per day). In this study we have focused on investigating tire wear particles and road-related metals (zinc, copper, lead, chromium, nickel, and the metalloid arsenic) in the soils of low traffic roads in rural areas (650-14,250 vehicles per day). Different explanatory factors were investigated, such as traffic density, speed, % heavy vehicles, organic matter content, annual precipitation, soil types and roadside slope profiles. The results show high levels of tire wear particles, from 2000 to 26,400 mg/kg (0.2-2.6 % tire wear in d.w. soil), which is up to five times higher compared to previously reported values in roadside soils of high traffic density areas. A weak but significant correlation was found between tire wear particles, traffic speed and the annual precipitation. No significant relationship was found between tire wear particles metals. The concentrations of metals were comparable to previous studies of high traffic areas of Norway, as well as both urban and rural soils in other countries. For the metals, all factors together explained 45 % of the variation observed, with traffic density (11 %) and organic matter content (10 %) as the most important single variables. The analysis of tire wear particles in soils using Pyrolysis Gas chromatography Mass Spectrometry is challenging, and the results presented demonstrate the need for pretreatment to remove organic matter from the samples before analysis.

A Simple Counting-Based Measurement for Paper Analytical Devices and Their Application

This work introduces the concept of a counting-based measurement on paper analytical devices (cPADs) to improve the utilization of numerous reactions. The design of cPADs consists of two layers of paper substrates; the first layer contains a central sample zone combined with a radial surrounded by 12 detection zones that are predeposited with the various reagents, and the second layer acts as a connection channel between the sample zone and each detection zone. The solution can vertically flow from the first to the second layer and then move through the area to each subsequent detection zone. The analyte level can be evaluated by counting the number of detection zones that change color from a blank signal. Furthermore, our cPADs exhibit a capability of implementation for a broad series of reactions. Compared to the dPAD technique, some reactions that are possibly difficult to apply in such devices can be wholly enabled in our devices. The final color reaction on cPADs can apparently occur due to its identity. We applied this technique to the monitoring of carbaryl (CBR) and copper ions (Cu²⁺) using different reactions, including azo-coupling and complexation, respectively. Accordingly, this indicates an excellent result validated using the more traditional methods. Our cPADs can be applied for rapid screening of both CBR and Cu²⁺ in water samples with outstanding accuracy and precision using a naked-eye measurement by a relatively unskilled person. We offer a simple platform on PADs for rapid screening, combining high cost-effectiveness within a miniaturized platform designed for use with onsite applications, which is thus suitable for several different reactions.