TITLE:
Methods Development for the Optical Determination of the Black Carbon Content of Loess Samples
AUTHORS:
Yan Mu, Xiaoguang Qin, Jiaqi Liu, Zhiqiang Yin
KEYWORDS:
Black Carbon, Optical Measurement Method, Loess Section, Pretreatment Procedure
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.6 No.7,
June
29,
2015
ABSTRACT: 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.