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Chemical remobilization of contaminant metals within floodplain sediments in an incising river system: implications for dating and chemostratigraphy
Author(s) -
HudsonEdwards K. A.,
Macklin M. G.,
Curtis C. D.,
Vaughan D. J.
Publication year - 1998
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/(sici)1096-9837(199808)23:8<671::aid-esp871>3.0.co;2-r
Subject(s) - overbank , chemostratigraphy , geology , geochemistry , authigenic , floodplain , manganese , pedogenesis , table (database) , earth science , environmental chemistry , sedimentary rock , structural basin , geomorphology , total organic carbon , chemistry , soil science , soil water , ecology , organic chemistry , facies , computer science , isotopes of carbon , biology , data mining
Metals such as Pb, Zn, Cd and Cu from historical mining activity have been used as stratigraphic markers for dating and provenancing vertically accreted, fine‐grained floodplain overbank deposits. This study presents evidence for chemical remobilization of these metals within overbank sediments in the Tyne basin, UK. The evidence includes: breakdown of metal‐bearing minerals (sulphides, carbonates, iron and manganese oxyhydroxides); shifts of chemical fractions within zones of relatively low pH towards more soluble and reactive phases; and accumulation of secondary iron and manganese oxyhydroxides at levels related to fluctuating water‐table levels or to the breakdown of organic matter. All of this suggests that fine, centimetre‐scale, chemostratigraphy using metal concentrations and ratios is unlikely to provide reliable data in river systems that have experienced, or are experiencing, major changes in water‐table levels, or pedogenesis. Coarse tens of centimetre‐ to metre‐scale, chemostratigraphy, when applied with caution, may still provide a means of delineating contaminated units. © 1998 John Wiley & Sons, Ltd.