Analytical methods, molecular structures and biogeochemical behaviors of dissolved black carbon

Abstract

Dissolved black carbon (DBC) is one of the most active fractions in the black carbon (BC) continuum and plays a significant role in the global dissolved organic matter (DOM) pool. Connecting the BC pool between territorial and marine environments, the biogeochemical processes of DBC are significant for many aspects of aquatic chemistry. Once entering the aquatic environment, DBC will undergo degradation and exert continuing effects on water ecology. DBC can change the migration and transport of pollutants and affect associated microbial communities. Therefore, the knowledge of the fate and transport of DBC is of great importance. In this work, the molecular structures of different DBC were examined and summarized to provide a basis for understanding the environmental processes of DBC. Current research progress on the photodegradation of DBC, interactions between DBC and microorganisms, and the effects of DBC on the fate and transport of contaminants were critically reviewed. The qualitative and quantitative analytical methods for DBC were assessed in detail. To date, the environmental behaviors of DBC are far from fully understood in part due to the lack of systematic methods. Compared with the relatively well-studied photodegradation of DBC, microbial transformation of DBC is poorly understood. Moreover, DBC is exposed to continuous light illumination and microbial metabolization, thus the combined effects of photodegradation and biodegradation are crucial to the cycling and turnover of DBC in aquatic environment and deserve further investigations. In addition, research on the sorption processes, redox reactions and DBC-assisted photo-transformations of contaminants is still at its emerging stages.