Distribution, input pathway and mass inventory of black carbon in sediments of the Gulf of Thailand, SE Asia

Abstract

a b s t r a c tThe coastal margins around Southeast Asia (SE Asia) may serve as an ideal location to study the sourcesink process of sedimentary black carbon (BC) because SE Asia has been identified as one of the major BC emission source regions in the world. This study provides an extensive picture of recent regional-scale sedimentary BC sequestration in the Gulf of Thailand (GOT), a tropical marine system in SE Asia. Generally, the sedimentary BC concentrations (0.07e3.99 mg/g) were in the low to moderate ranges of those obtained in other coastal sediments around the world. Regional variability of the BC and its correlation with the sediment grain size and total organic carbon (TOC) content indicated a general hydrodynamic constraint on BC occurrence in the lower Gulf in contrast to the upper Gulf with a more source dependence due to the direct land-based input. BC/TOC% values and the varied BC components (char and soot), as well as their correlations suggested that char was the predominant constituents of sedimentary BC both in the upper and lower Gulf, which could be mainly derived from biomass burning and entered into the nearshore region through direct fluvial transport and surface run-off. The estimated BC burial flux (~212 mg/cm 2 /y) and mass inventory (~200 Gg/y) in the GOT on the hundred-year timescale were of the same order of magnitude compared with other oceanic margins, and thus the tropical shelf sediments from SE Asia could serve as an important sink of land-emitted BC.

Application of PMF receptor model merging with PAHs signatures for source apportionment of black carbon in the continental shelf surface sediments of the Bohai and Yellow Seas, China

“…The blank samples ( n = 9) yielded nondetectable BC concentrations, and the relative standard deviation of nine pairs of replicate analyses was in the range of 0–10%, and averaged within 5%. The BC concentration measured in NIST 1941b was 10.45 ± 1.23 mg/g (dry weight, n = 9), which was well in accordance with the values reported by recent studies [ Han et al ., ; Cong et al ., ; Hu et al ., ], suggesting that the BC analytical method used here was credible and reproducible.…”

“…BC is not a well‐defined component, but rather exists as a combustion/temperature continuum [ Masiello , ]. Scientists often classify BC into two subtypes, i.e., char‐BC and soot‐BC [ Hammes et al ., ; Han et al ., ; Hu et al ., ]. Although fossil fuels combustion and biomass burning both produce BC, the relative proportions of the char‐BC and soot‐BC (char‐BC/soot‐BC) varies as a function of the fuel types and other factors.…”

Large-river dominated black carbon flux and budget: A case study of the estuarine-inner shelf of East China Sea, China

“…In the present study, wet-chemical pre-treatment coupled with thermal optical reflectance (TOR) detection was applied to quantify the sedimentary BC, owing to its proven ability for effectively differentiating between char and soot (Han et al, 2007a;Han et al, 2011;Han et al, 2012;Han et al, 2015b;Hu et al, 2016). In brief, thawed, freezedried, and ground sediments (b80 meshes) were processed with hydrochloric and hydrofluoric acids (HCl/HF) to remove the inorganic materials, such as carbonates, silicates, and some metals and metallic oxides.…”

“…Most of these pioneering investigations are geographically confined within American and European coastal shelf areas, such as the Gulf of Maine (Gustafsson and Gschwend, 1998;Flores-Cervantes et al, 2009), Washington Coast (Dickens et al, 2004), Northern European Shelf (Sánchez-García et al, 2012), Gulf of Cádiz (Sánchez-García et al, 2013), and Pan-Arctic Shelves (Guo et al, 2004;Elmquist et al, 2008;Yang and Guo, 2018). However, only little attention has been paid to the Asian coastal shelves (Fang et al, 2015;Hu et al, 2016;Huang et al, 2016), where BC emissions from Asian continent are estimated to contribute more than half of the global anthropogenic BC emissions (Bond et al, 2004). This implies that a more detailed study of BC in the coastal shelf of Asian countries, especially in the largest BC emitter of China (Wang et al, 2012), will to a large extent deepen our understanding of the influence of sedimentary BC sink on the regional and even global carbon cycles and budgets.…”

Release of Black Carbon From Thawing Permafrost Estimated by Sequestration Fluxes in the East Siberian Arctic Shelf Recipient

“…It has been estimated, based on limited early data, that 90% of the marine deposition of BC occurs on continental shelves (Suman et al, ), yet the magnitude of this transfer to marine sediments is still controversial (Dickens et al, ; Elmquist et al, ; Flores‐Cervantes et al, ; Gustafsson & Gschwend, ; Lohmann et al, ; Mitra et al, , ). Previous studies have investigated dissolved BC in the marine system (Coppola & Druffel, ; Jaffe et al, ; Stubbins et al, ; Ziolkowski & Druffel, ), and other authors studied the fluxes of BC into marine sediments in only a few coastal margins, such as the Gulf of Maine (Gustafsson & Gschwend, ), the South Atlantic Ocean (Lohmann et al, ), the Northern European Shelf (Sanchez‐Garcia et al, ), the East China Sea (Huang et al, ), and the Gulf of Thailand (Hu et al, ).…”