The driving factors of new particle formation and growth in the polluted boundary layer

Abstract

Abstract. New particle formation (NPF) is a significant source of atmospheric particles, affecting climate and air quality. Understanding the mechanisms involved in urban aerosols is important to develop effective mitigation strategies. However, NPF rates reported in the polluted boundary layer span more than 4 orders of magnitude, and the reasons behind this variability are the subject of intense scientific debate. Multiple atmospheric vapours have been postulated to participate in NPF, including sulfuric acid, ammonia, amines and organics, but their relative roles remain unclear. We investigated NPF in the CLOUD chamber using mixtures of anthropogenic vapours that simulate polluted boundary layer conditions. We demonstrate that NPF in polluted environments is largely driven by the formation of sulfuric acid–base clusters, stabilized by the presence of amines, high ammonia concentrations and lower temperatures. Aromatic oxidation products, despite their extremely low volatility, play a minor role in NPF in the chosen urban environment but can be important for particle growth and hence for the survival of newly formed particles. Our measurements quantitatively account for NPF in highly diverse urban environments and explain its large observed variability. Such quantitative information obtained under controlled laboratory conditions will help the interpretation of future ambient observations of NPF rates in polluted atmospheres.

Synergistic HNO3–H2SO4–NH3 upper tropospheric particle formation

“…At this same ammonia concentration, we measured J 1.7 = 6.1 cm −3 s −1 at 2.3 × 10 6 cm −3 H 2 SO 4 , demonstrating the much faster rate of H 2 SO 4 –NH 3 nucleation (not shown). This measurement is consistent with models on the basis of previous CLOUD studies of H 2 SO 4 –NH 3 nucleation 18 , 19 , as illustrated by the model simulations for 4.0 × 10 6 cm −3 sulfuric acid (red solid curve). The blue circles show our measurements of J 1.7 for HNO 3 –H 2 SO 4 –NH 3 nucleation at 4.0 × 10 6 cm −3 sulfuric acid and (1.6–6.5) × 10 8 cm −3 ammonia, in the presence of 1.5 × 10 9 cm −3 nitric acid (the event shown in Extended Data Fig.…”

“…The nucleation model is on the basis of the thermodynamic model for H 2 SO 4 –NH 3 nucleation described in detail previously 18 , 19 . It is developed from the general dynamic equations 60 , to calculate the production and losses for each cluster/particle size to determine the formation rates of the acid–base clusters.…”

“…The black diamond shows the CLOUD measurement of HNO 3 –NH 3 nucleation at 1.5 × 10 9 cm −3 HNO 3 , 6.5 × 10 8 cm −3 NH 3 and with H 2 SO 4 below the detection limit of 5 × 10 4 cm −3 . The red solid curve is J 1.7 versus ammonia concentration at 4.0 × 10 6 cm −3 sulfuric acid from a H 2 SO 4 –NH 3 nucleation parameterization on the basis of previous CLOUD measurements 18 , 19 . The blue circles show the CLOUD measurements of HNO 3 –H 2 SO 4 –NH 3 nucleation at 4.0 × 10 6 cm −3 H 2 SO 4 , 1.5 × 10 9 cm −3 HNO 3 and (1.6–6.5) × 10 8 cm −3 NH 3 .…”

The effect of COVID-19 restrictions on atmospheric new particle formation in Beijing

“…In the first stage, a key concern is the identity of the clustering molecules. On one hand, several laboratory studies (Almeida et al, 2013;Xiao et al, 2021) and ambient measurements (Yao et al, 2018;Yin et al, 2021;Cai et al, 2021b;Deng et al, 2020) indicate that clustering between sulfuric acid (SA) and amines drives the initial NPF in polluted environments. On the other hand, there are also studies suggesting that organic acids formed from oxidation of traffic emissions are key clustering species (Guo et al, 2020).…”

The Effect of Using a New Parameterization of Nucleation in the WRF-Chem Model on New Particle Formation in a Passive Volcanic Plume

“…The results of this work show that the nucleation process depends on the availability of SO 2 and H 2 SO 4 , and atmospheric conditions (high-pressure systems) [27]. The investigation of the NPF in the urban boundary layer using CERN CLOUD chamber (Cosmic Leaving Outdoor Droplets, [28]) and mixtures of anthropogenic vapors (H 2 SO 4 , ammonia, dimethylamine, NO x , ozone, water, and several anthropogenic volatile organic compounds) indicates that the formation of sulfuric acid-base clusters is the first stage in the NPF process [29].…”