TY - JOUR
T1 - Boron isotope composition of coals
T2 - A potential tracer of organic contaminated fluidsEditorial handling by R.S. Harmon
AU - Williams, Lynda
AU - Hervig, Richard
N1 - Funding Information:
This work was funded by a grant from the US Department of Energy (DE-FG03-94ER14414). The authors thank Mike Lewan, USGS Denver, The Penn State Coal Repository (PSOC) and Argonne Premium Coal Repository (both supported by DOE) for supplying kerogen/coal samples. Jon Mull supplied computer technical support, and Al Higgs provided electronic support for the SIMS.
PY - 2004/10
Y1 - 2004/10
N2 - The B-content of coals from sedimentary basins is a function of the primary depositional environment and secondary enrichments. Boron has been used to infer paleo-environments of coal deposits, and environmental impact of coal burning power plants. To improve our understanding of B in organic matter, this study used secondary ion mass spectrometry to measure the B-isotopic composition of 25 coals and three kerogens (Type I, II and III). Results show that coal is 10B-enriched compared to most terrestrial waters. The δ11B values measured show large variability within a single 'homogenized' coal sample indicating that B is heterogeneously bound in various organic macerals. Of greater importance is the observation that all coal δ11B values are negative. The lowest δ11B measured was -70‰ representing the lightest B-isotopic ratios ever reported for terrestrial materials. Bulk analyses of coals may not reveal isotope ratios this low because of the averaging of values from different organic macerals having different δ11B values. This discovery may be important for tracing organic contaminants in fluids. When organic matter is heated during burial, the isotopically light B partitions into fluid phases. The very low δ11B of organic products compared to most groundwaters may be useful in tracing fluids derived from organic sources.
AB - The B-content of coals from sedimentary basins is a function of the primary depositional environment and secondary enrichments. Boron has been used to infer paleo-environments of coal deposits, and environmental impact of coal burning power plants. To improve our understanding of B in organic matter, this study used secondary ion mass spectrometry to measure the B-isotopic composition of 25 coals and three kerogens (Type I, II and III). Results show that coal is 10B-enriched compared to most terrestrial waters. The δ11B values measured show large variability within a single 'homogenized' coal sample indicating that B is heterogeneously bound in various organic macerals. Of greater importance is the observation that all coal δ11B values are negative. The lowest δ11B measured was -70‰ representing the lightest B-isotopic ratios ever reported for terrestrial materials. Bulk analyses of coals may not reveal isotope ratios this low because of the averaging of values from different organic macerals having different δ11B values. This discovery may be important for tracing organic contaminants in fluids. When organic matter is heated during burial, the isotopically light B partitions into fluid phases. The very low δ11B of organic products compared to most groundwaters may be useful in tracing fluids derived from organic sources.
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U2 - 10.1016/j.apgeochem.2004.02.007
DO - 10.1016/j.apgeochem.2004.02.007
M3 - Article
AN - SCOPUS:2942711909
SN - 0883-2927
VL - 19
SP - 1625
EP - 1636
JO - Applied Geochemistry
JF - Applied Geochemistry
IS - 10
ER -