Occurrence, Migration, and Transformation of Black Carbon in Environmental Matrix and Its Influence on the Environmental Fate of Coexisting Pollutants: A Review

Black carbon (BC) is a carbonaceous residue produced via incomplete combustion of fossil fuels or biomass, including soot and biochar. BC is ubiquitous in the natural environment, negatively impacting human health and climate. Based on in-depth research, its positive role in removing pollutants has attracted extensive attention. First, this paper briefly summarizes the number and growth trend of BC publications from 1999 to 2022. Second, the source, migration and transformation, and detection methods of BC and its potential risks to the environment and health were introduced. Moreover, the mechanisms of BC influence on the fate and environmental effects of coexisting pollutants are summarized. This review provides a reference for understanding the sources, risks, and dynamic changes of BC and its impact on the behavior and environmental effects of coexisting pollutants. Considering the future application of BC in the environment and its important role in the carbon cycle, the following aspects require further study: (1) unifying the definition standard of BC; (2) developing more accurate and reliable methods for separating and quantifying BC than existing methods; (3) exploring methods to analyze the structural characteristics of BC, which is conducive to thoroughly studying the fate and impact on other pollutants; (4) assessing the ecological effects and mechanisms of BC of different properties (such as particle size, color, and hydrophobicity), especially long-term risk assessments, which are beneficial to the dose control and type selection of BC for environmental remediation; and (5) investigating physical and chemical properties of BC from different sources and production methods as well as the effects of environmental factors on the behavior and toxicity of coexisting pollutants, which will help regulate and improve the removal efficiency of BC for pollutants.