Spatiotemporal Trends of Elemental Carbon and Char/Soot Ratios in Five Sediment Cores from Eastern China Marginal Seas: Indicators of Anthropogenic Activities and Transport Patterns

Abstract

Elemental carbon (EC), the highly recalcitrant carbonaceous material released exclusively from fossil fuel combustion and biomass burning, is a preferred geochemical agent for evaluating anthropogenic activities. We investigated the spatiotemporal trends of EC and char/soot ratios (char and soot, the two subtypes of EC, differ in formation mechanisms and physicochemical characteristics) in five sediment cores from eastern China marginal seas, spatially spanning from inshore coastal mud areas to offshore remote mud areas. The temporal profiles of EC depositional fluxes closely tracked socioeconomic development in China over the past ∼150 years, with the most pronounced increasing trend beginning in the early 1980s, commensurate with the implementation of national policy of Reform and Open in 1978. The temporal EC profiles in China differed significantly from those in European/American countries, reflecting their different socioeconomic development stages. The spatiotemporal trends of char/soot ratios were also highly informative. Temporally, they decreased from bottom to subsurface layers, indicating the switch of China from an agricultural economy to an industrial economy during the 20th century. Spatially, they decreased from inshore to offshore areas, suggesting the differential transport patterns of EC among these sampling regimes.

Particulate and Dissolved Black Carbon in Bohai and Laizhou Bays, China: Distributions, Sources, and Contrasts Under Two Distinct Fluvial Hydrological Regimes

“…To date, there have been plenty of investigations concerning PBC on the regional atmosphere, soils, sediments, and coastal wetlands in Bohai Rim (Li and Bai, 2009;Liu et al, 2011;Chen et al, 2013;Huang et al, 2014;Andersson et al, 2015;Fang et al, 2015;Zhang et al, 2015;Fang et al, 2016;Liu et al, 2016;Xu et al, 2017;Fang et al, 2018b;Shao et al, 2018). In comparison, however, the available studies draw relatively less attention on PBC in the aquatic environments (such as the riverine water and coastal seawater), let alone the analytically highly complicated and challengeable DBC (Wang et al, 2016;Xu et al, 2016;Fang et al, 2018a;Qi et al, 2020;Fang et al, 2021).…”

The ancient Chinese civilization left remarkable signals in the marine environment since the Bronze Age

“…Black carbon (BC) is a highly aromatic, recalcitrant carbon species released both from the wildfire and anthropogenic fire for the main energy utilization in ancient human civilization. It has two subtypes, char and soot (8,9), which can be distinguished by thermal optical reflectance due to their different burning temperatures (10,11). BC is widely distributed in lake and ocean sediments via transportation by atmospheric circulation and surface runoff (12).…”

“…Char particles (1~100 µm) are residues of combustion at temperatures of 300~600℃ that retain some of the morphological and structural features of their precursors, and are a function of biomass burning. Soot particles (< 1 µm) are produced during high-temperature combustion (> 600℃), which is strongly related to anthropogenic fuels (e.g., petroleum, coal, and charcoal) or highintensity biomass burning (8,9,10,13,14,15). The sedimentary records of char and soot can provide information for tracking past changes in fire activity forced by climate change or human activities on multi-decadal to millennial scales (16).…”

“…From the time when human beings use fire by biomass fuels as early as the middle Pleistocene to the period of the large-scale use of fossil fuels in the industrial revolution, there have been several stages in the evolution of human civilization, Neolithic Age, Bronze Age, and Iron Age. Sediment cores provides striking evidence of past contamination linked to the civilization evolution in various continents during human history (9,20). Northern China is the birthplace of Chinese civilization, which is one of the oldest human civilizations.…”

Amplification of black carbon light absorption induced by atmospheric aging: temporal variation at seasonal and diel scales in urban Guangzhou

“…A coating of brown carbon (BrC) can further amplify the light absorption compared to a transparent coatings (Lack and Cappa, 2010). Recent studies suggested that BC mixing state diversity also affects the bulk E abs (Fierce et al, 2016;Matsui et al, 2018;Cappa et al, 2019).…”