Various particulate matters (PM) and associated carbonaceous aerosols released from open biomass burning (including open straw burning, grass and forest fires) are major sources of atmospheric pollutants. Northeast China is a central region with high forest and grass coverage, as well as an intensive agricultural area. In this study, the FINN (Fire INventory from Ncar) emission data was used to analyze the spatiotemporal variations of PM and associated carbonaceous aerosol component (PM_2.5, PM₁₀, OC and BC) emissions from open biomass burning in Northeast China from 2002 to 2016. The results show that the total amount of annual PM_2.5, PM₁₀, OC and BC emissions was estimated to be 59.0, 70.6, 31.5, and 4.3 kilotons, respectively, from open biomass burning over Northeast China, averaged from 2002 to 2016, with significant inter-annual variations in amplitudes from 28.0 to 122.3, 33.7 to 144.1, 15.0 to 65.0, and 2.1 to 8.6 kilotons. The regional PM_2.5, PM₁₀, OC and BC emissions showed significant seasonal variations with highest emissions in spring (with a seasonal peak in April), followed by autumn (with a seasonal peak in October), summer, and winter in Northeast China; high emissions were concentrated in the forests and grasslands with natural fires, as well as over agricultural areas with crop straw burning from human activities. The PM_2.5, PM₁₀, OC and BC emissions over forest areas presented decreasing trends, while the emissions over farmlands showed increasing trends in Northeast China during 2002–2016; this reflects on the dominance of biomass burning that shifted from forestland with natural fires to farmlands with increasing human activities. Three key meteorological drivers—strong near-surface wind speed, high air temperature and low relative humidity—were identified as having significant positive impacts on the inter-annual variations of PM_2.5, PM₁₀, OC and BC emissions from open biomass burning in Northeast China.

Sampling on different substrates is commonly used in laboratory and field studies to investigate the morphology and mixing state of aerosol particles. Our focus was on the transformations that can occur to the collected particles during storage, handling, and analysis. Particle samples were prepared by electrostatic deposition of size-classified sodium chloride, sulfuric acid, and coated soot aerosols on different substrates. The samples were inspected by electron microscopy before and after exposure to various environments. For coated soot, the imaging results were compared against mass-mobility measurements of airborne particles that underwent similar treatments. The extent of sample alteration ranged from negligible to major, depending on the environment, substrate, and particle composition. We discussed the implications of our findings for cases where morphology and the mixing state of particles must be preserved, and cases where particle transformations are desirable.

Black carbon is a short-lived climate warming agent and serves as a crucial factor influencing the climate. Numerous models, observations, and laboratory studies have been conducted to quantify black carbon’s direct or indirect impacts on the climate. Here, we applied bibliometric analysis to identify research trends and key topics on black carbon in the climate field. Based on the Web of Science (WOS) Core Collection database, a total of 4903 documents spanning the period from 2000 to 2023 were retrieved and screened, focusing on the topic of black carbon in the climate field, resulting in the Black-Carbon Climate Local (BCL) dataset. Our study examines the influence and trends of major countries, institutions, and authors in this field. The results show that China and the United States hold leading positions in terms of the number of publications. Based on keyword networks, the BCL dataset is segmented into six distinct research directions, and representative keywords of each direction include biomass burning, radiative forcing, air pollution, aerosol optical depth, optical properties, and biochar. This study helps to identify the current research status and trends of black carbon in the climate, highlighting main research directions and emerging topics.

A new particle swarm optimization based on dynamic parameter modification is proposed in this paper (Dynamic Parameter Modification Particle Swarm Optimizer, DPSO). In DPSO algorithm , is doing oscillating decay breaking through the constraint of topical linear decreasing, and the Euclidean distance and is calculated, which respectively stand for the Euclidean distances form the position of particle to the best position that the particle has passed and the best position that all the particles have passed under the time . Parameters and of topical PSO are modified dynamically based on the comparison of and in order to coordinate between global search and local search. Then find out the optimal value of Goldstein-Price function using topical PSO and the improved DPSO respectively, and the results demonstrate that compared to topical PSO, DPSO algorithm avoids falling into the local minimum and improves the search efficiency.

Air quality issues in megacities have significant implications for public health and economic development. This study analyzes the impacts of long-term emission reduction policies and short-term emergency control measures on the concentrations of major air pollutants, using Chengdu and Chongqing as case studies and applying meteorological normalization methods.The results from long-term monitoring data indicate significant reductions in the concentrations of PM2.5, PM10, NO2, SO2, and CO, with Chengdu achieving particularly notable reductions in SO2, NO2, and CO. However, O3 concentrations in both cities have shown a slightly increasing trend, especially in Chengdu, primarily due to reduced NO2 levels, which decreased ozone suppression.The study found that the introduction of new monitoring stations can distort city-level pollutant trends. After adjustment, the data more accurately reflected pollutant concentration changes, with the NO2 trend in Chongqing being most affected by the introduction of new monitoring stations. To further explore these trends, seasonal analysis revealed that wintertime pollutant concentrations showed the most significant decreases during the initial phase of emission reductions, however this effectiveness has changed in recent years. Meanwhile, challenges related to O3 formation during summer have intensified. Further analysis demonstrated that Chengdu’s traffic control policies were significantly more effective than Chongqing’s in reducing NO2. Additionally, comparisons between COVID-19 control and non-control periods revealed different response patterns of various pollutants to short-term and long-term measures.This study provides new insights into the differences and effectiveness of pollution control strategies in megacities and offers scientific support for optimizing future air quality management policies.