Brake wear-derived particles:Single-particle mass spectral signatures and real-world emissions

Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter(PM).The single-particle spectral fingerprints of brake wear particles(BWPs)provide essential information for understanding their formation mechanism and atmospheric contributions.Herein,we obtained the single-particle mass spectra of BWPs by combining a brake dynamometer with an online single particle aerosol mass spectrometer and quantified real-world BWP emissions through a tunnel observation in Tianjin,China.The pure BWPs mainly include three distinct types of particles,namely,Bacontaining particles,mineral particles,and carbon-containing particles,accounting for 44.2%,43.4%,and 10.3%of the total BWP number concentration,respectively.The diversified mass spectra indicate complex BWP formation pathways,such as mechanical,phase transition,and chemical processes.Notably,the mass spectra of Ba-containing particles are unique,which allows them to serve as an excellent indicator for estimating ambient BWP concentrations.By evaluating this indicator,we find that approximately 4.0%of the PM in the tunnel could be attributable to brake wear;the real-world fleet-average emission factor of 0.28 mg km
1 veh
1 is consistent with the estimation obtained using the receptor model.The results presented herein can be used to inform assessments of the environmental and health impacts of BWPs to formulate effective emissions control policies.

Evaluation of pharmaceutical activities of G-protein coupled receptor targeted pharmaceuticals in Chinese wastewater effluent

The occurre nce of biologically active pharmaceuticals in aquatic enviro nments raised the potential risks to aquatic species.Among these marketed biological active pharmaceuticals,it has been estimated that40%of them target G-protein-coupled receptors(GPCRs).We have illustrated pharmaceutical activities of GPCR targeted pharmaceuticals in English and Japanese wastewater by the in vitro transforming growth factor-α(TGFα)shedding assay.However,as the most important producer and consumer of pharmaceuticals,the occurrence of GPCR targeted pharmaceuticals in China had remained unclear.In this study,we investigated the pharmaceutical activities of GPCR targeted pharmaceuticals in secondary effluents of Chinese wastewater treatment plants.We discovered antagonistic activities against angiotensin(AT1)receptor at up to 7.2×102 ng-valsartan-equivalent quantity/L in Chinese wastewater for the first time as well as agonistic activities against dopamine(D2)receptor.Furthermore,in parallel with the assay,we determined concentrations of GPCR targeted pharmaceuticals in target wastewater by liquid chromatography coupled with tandem mass spectrometry(LC-MS/MS).Through the comparison of predicted antagonistic activities calculated by concentrations and potency values from the assay,we found that the measured antagonistic activities against AT1 receptor from the assay were higher than the predicted AT1 activities from valsartan,irbesartan,and losartan,indicating the potential existence of other unknown AT1 antagonists in wastewater.