Unveiling the spatial patterns and potential sources of black carbon in lake sediments from diverse developing areas in a representative mining and metallurgy region of Central China

PurposeBlack carbon (BC) is a crucial component of organic carbon (OC), forming due to incomplete combustion of fossil fuels and biomass. Identifying the distribution characteristics and possible sources of BC is essential for managing carbonaceous pollution in freshwater lakes, especially in a mining and metallurgy region, where the metallurgical activities poses a significant threat to the aquatic ecological environment. This study examined the distribution characteristics and potential sources of BC in surface sediments from three distinct development areas.Materials and methodsIn January 2019, 32 surface sediment samples were collected, including 17 from Wang Lake (WL), five from Lianhua Lake (LL), and 10 from Mati Lake (ML). The BC measurements were conducted using the thermal-optical reflectance (TOR) method with quality control. Additionally, empty silver capsules were thermally treated and acidified as blank controls. Statistical analyses, correlation analyses, BC/OC ratios, and char/soot ratios were employed to examine the spatial distribution and potential sources of BC in the different lakes.Results and discussionThe measured BC concentrations were 0.722 +/- 0.339, 1.99 +/- 1.90 and 0.748 +/- 0.313 mg g-1 in WL, LL, and ML, respectively. Spatial analysis revealed elevated BC levels in LL, WL, and specific areas within WL. The char/soot ratios exhibited variability, with lower ratios in LL, higher ratios in ML, and variable ratios in WL. Correlation analysis and the relationship between BC/OC ratios and char/soot ratios indicated the influence of local biomass combustion deposition on BC accumulation in lake sediments. Furthermore, by comparing BC/OC ratios and char/soot ratios with local developmental characteristics, contributions from vehicular emissions and coal combustion deposition were observed in LL. The leakage of fossil fuels from boats may also contribute to the accumulation of carbon compounds in WL. Long-term metallurgical-related activities involving various sources of energy burning may account for the BC accumulation in ML, located in an industrial area.ConclusionsHuman activities significantly influenced the distribution and sources of BC in sediments from different types of lakes in areas with diverse developmental characteristics. These findings provide valuable insights for researchers and government authorities to understand the main contributions of BC to sediment and develop targeted policies for preventing and controlling carbonaceous pollution based on the unique developmental characteristics in similar mining areas worldwide.

Automated summary

This study examines the distribution characteristics and potential sources of black carbon (BC) in surface sediments from three distinct development areas. Human activities significantly influenced the distribution and sources of BC in sediments from different types of lakes in areas with diverse developmental characteristics.