Black carbon records in Chinese Loess Plateau over the last two glacial cycles and implications for paleofires

Wang, X.; Peng, Ping’an; Ding, Zhongli

doi:10.1016/j.palaeo.2005.03.023

Cited by 83 publications

(34 citation statements)

References 29 publications

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“…In the (NaPO 3 ) 6 pretreatment (Figure 12), the resultant BC concentration of loess samples estimated by using the slope of Equation (9) varies between 0.012% -0.025%. This is the same order of magnitude as the 0.01% -0.054% result of Han et al using the TOR method [29], but less than the average content 0.124% of the same study area published by Wang et al using a chemical method [41].…”

Section: ) Comparison Of Bc Contents Of Various Pretreatmentssupporting

confidence: 53%

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Methods Development for the Optical Determination of the Black Carbon Content of Loess Samples

Qin²,

Liu³

et al. 2015

AJAC

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We evaluate the applicability of an optical transmission measurement method commonly used for the analysis of the Black Carbon (BC) content of aerosol sample, to determine the BC content of loess sediments. A number of different sample pretreatment procedures are developed and compared, leading to an optimum preparation process. The results include: 1) Subtraction of the optical attenuation values before and after heating of the sample filters ("ΔATN") varies linearly with the sample mass. The slope of the regression line provides the best determination of BC concentration. 2) When the sample mass is small, (NaPO3)6 pretreatment is best for BC measurement, and the BC concentration results are given by the slope of the regression between ΔATN and sample mass, for a series of samples of varying mass. 3) HF pretreatment accompanied by centrifugation and rinsing may produce a negative bias on the result. 4) Replicate measurements of BC for loess samples showed a maximum deviation less than 5.6%, suggesting that measurements of the BC concentration of a sequence of loess samples could determine variations to this degree of significance. 5) The overall trends of BC concentration in loess section sequences were similar for all chemical pretreatments. The BC concentration result for replicate samples is comparable when pretreated by the same procedure.

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Section: ) Comparison Of Bc Contents Of Various Pretreatmentssupporting

confidence: 53%

“…It is known that the periodic variability of the composition of loess-paleosol sequences reflects changes between dry and wet periods [40]; and the concentration of BC reflects changes similar to climatic fluctuations [41].…”

Section: Introductionmentioning

confidence: 99%

Methods Development for the Optical Determination of the Black Carbon Content of Loess Samples

Qin²,

Liu³

et al. 2015

AJAC

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“…Few other studies to date have quantified BC concentrations over the whole soil profile (see Kleber et al, 2003;Wang et al, 2005;Rodionov et al, 2006). Most BC concentration studies report only the topsoil values (to 30 cm depth).…”

Section: Black Carbon Concentrationsmentioning

confidence: 99%

Centennial black carbon turnover observed in a Russian steppe soil

et al. 2008

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Abstract. Black carbon (BC), from incomplete combustion of fuels and biomass, has been considered highly recalcitrant and a substantial sink for carbon dioxide. Recent studies have shown that BC can be degraded in soils. We use two soils with very low spatial variability sampled 100 years apart in a Russian steppe preserve to generate the first wholeprofile estimate of BC stocks and turnover in the field. Quantities of fire residues in soil changed significantly over a century. Black carbon stock was 2.5 kg m −2 , or about 7-10% of total organic C in 1900. With cessation of biomass burning, BC stocks decreased 25% over a century, which translates into a centennial soil BC turnover (293 years best estimate; range 182-541 years), much faster than so-called inert or passive carbon in ecosystem models. The turnover time presented here is for loss by all processes, namely decomposition, leaching, and erosion, although the latter two were probably insignificant in this case. Notably, at both time points, the peak BC stock was below 30 cm, a depth interval, which is not typically accounted for. Also, the quality of the fire residues changed with time, as indicated by the use benzene polycarboxylic acids (BPCA) as molecular markers. The proportions of less-condensed (and thus more easily degradable) BC structures decreased, whereas the highly condensed (and more recalcitrant) BC structures survived unchanged over the 100-year period. Our results show that BC cannot be assumed chemically recalcitrant in all soils, and other explanations for very old soil carbon are needed.

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“…The changes in soil organic matter composition due to agricultural practice could be considered part of the archaeological record, but the marker substances that allow the assessment of anthropogenic activities are diverse and their long-term fate in soil is often unknown (Heron, 2004). The fire-history of a site can be reconstructed by the presence of macrocharcoal or by applying chemical methods to determine the amount of charred organic matter in soil samples (e.g., Bird and Cali, 1998;Carcaillet et al, 2002;Wang et al, 2005;Gerlach et al, 2006). However, burning of grass or herbaceous vegetation does not produce large amounts of charcoal particles and chemical methods are rarely applied.…”

Section: Introductionmentioning

confidence: 99%

Short-chain n-alkanes (C16–20) in ancient soil are useful molecular markers for prehistoric biomass burning

Eckmeier

Wiesenberg

2009

Journal of Archaeological Science

103

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The incorporation of plant biomass into soil usually leads to long-chain n-alkanes with a relative predominance of odd carbon numbered homologues. Contrastingly, an increase in short-chain even carbon numbered n-alkanes was found in charred biomass with progressing temperatures. We applied lipid analysis to buried ancient topsoils that contained charred organic matter and to corresponding control soils, which were characterized by a lighter color and lower contents of charred materials. Commonly, the proportion of lipid extracts was found to be lower in the ancient soil than in the control samples, which indicated an enhanced degradation of organic matter, e.g., by thermal degradation. All samples displayed a particular pattern of short-chain and even carbon numbered n-alkanes (maximum at n-C16 or n-C18). The ratios CPI (carbon preference index) and ACL (average chain length) for the investigated soil samples matched the ratios found for maize and rye straw charred at 400 °C or 500 °C, respectively. These molecular ratios indicate the presence of charred biomass. The predominance of short-chain and even carbon numbered n-alkanes was a result of thermal degradation of biomass. The degradation products were preserved in ancient soils and could be applied as molecular markers in archaeological or palaeoenvironmental research.Author's personal copy b s t r a c tThe incorporation of plant biomass into soil usually leads to long-chain n-alkanes with a relative predominance of odd carbon numbered homologues. Contrastingly, an increase in short-chain even carbon numbered n-alkanes was found in charred biomass with progressing temperatures. We applied lipid analysis to buried ancient topsoils that contained charred organic matter and to corresponding control soils, which were characterized by a lighter color and lower contents of charred materials. Commonly, the proportion of lipid extracts was found to be lower in the ancient soil than in the control samples, which indicated an enhanced degradation of organic matter, e.g., by thermal degradation. All samples displayed a particular pattern of short-chain and even carbon numbered n-alkanes (maximum at n-C 16 or n-C 18 ). The ratios CPI (carbon preference index) and ACL (average chain length) for the investigated soil samples matched the ratios found for maize and rye straw charred at 400 C or 500 C, respectively. These molecular ratios indicate the presence of charred biomass. The predominance of short-chain and even carbon numbered n-alkanes was a result of thermal degradation of biomass. The degradation products were preserved in ancient soils and could be applied as molecular markers in archaeological or palaeoenvironmental research.

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Black carbon records in Chinese Loess Plateau over the last two glacial cycles and implications for paleofires

Cited by 83 publications

References 29 publications

Methods Development for the Optical Determination of the Black Carbon Content of Loess Samples

Methods Development for the Optical Determination of the Black Carbon Content of Loess Samples

Centennial black carbon turnover observed in a Russian steppe soil

Short-chain n-alkanes (C16–20) in ancient soil are useful molecular markers for prehistoric biomass burning

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