# Identification and Characterization of Atmospheric Nickel-Containing Particles in Guangzhou After the Implementation of the Clean Fuel Policy

## TL;DR

This study examines nickel-containing particles in Guangzhou's air and finds that a clean fuel policy reduced their levels, improving air quality.

## Contribution

The study identifies and characterizes distinct types of nickel-containing particles and evaluates the impact of a clean fuel policy on their concentrations.

## Key findings

- Nickel particles account for 0.08% of PM2.5 by number, consistent with prior mass fraction reports.
- Three types of nickel-containing particles (Ni-fresh, Ni-aged, Ni-ash) were identified with distinct sources and characteristics.
- The clean ship fuel policy reduced nickel particle concentrations, benefiting air quality in Guangzhou.

## Abstract

Nickel, as a toxic trace element in fine particulate matter (PM2.5), has detrimental effects on both air quality and human health. Based on measurements from 2020 to 2021 using a single-particle aerosol mass spectrometer (SPAMS), this study investigates the properties of nickel-containing particles (NCPs) in Guangzhou. The composition, sources, and temporal trends of NCPs were evaluated and the impact of the clean ship fuel policy introduced in 2020 was also examined. The key findings include: (1) Nickel particles account for 0.08% number fraction of PM2.5, which is consistent with previously reported mass fraction in PM2.5. (2) Three distinct types of NCPs were identified, including Ni-fresh, Ni-aged, and Ni-ash. Each type exhibits unique characteristics in size distribution, wind direction dependence, sources, and temporal variations. Ni-fresh particles originate from shipping emissions in the Huangpu Port area 2 km away and are the major contributors to fine nickel particles in the region. (3) Ni-aged and Ni-ash particles, which carry secondary components, tend to be larger (>500 nm) and are representative of regional or background nickel particles. (4) The implementation of the clean ship fuel policy has effectively reduced the number concentrations of NCPs and is beneficial to regional and local air quality.