Ganga Basin Sediment (GBS): A Potential Geological Reference Material for Tropical Rivers

Abstract

ABSTRACT The Himalayan river system (HRS) constitutes a major conduit for continental material transport to the adjacent oceans. The unresolved geological complexity and active tectonics of the Himalaya bring heterogeneity in sediment geochemistry. There is no known certified reference material (CRM) that represents the geochemical heterogeneity of HRS and large tropical rivers (LTR) though they rank first in terms of sediment transport and water discharge. As an ongoing exercise to develop reference material to calibrate the instruments and to validate the geochemical results, a river bedload sediment sample from the Ganga river basin (GBS) which is representative of both HRS and LTR was collected in sufficient quantity and characterized for its geochemical composition using inductively coupled plasma instrumentation techniques (ICP-OES and ICP-MS). The GBS has been analyzed for major, trace, and rare earth elements (REEs) to infer the homogeneity and suitability of geological material for reference material characterization through the test of reproducibility and representativeness. The precision of measurement (% RSD) within and across the four analytical sessions is less than < 7 % for most of the elements measured. The method is validated with respect to precision, limit of detection (LOD), limit of quantification (LOQ), and measurement uncertainties by analyzing CRMs. The concentration values of GBS are reproducible. The GBS composition also showed a good correlation with published datasets from the HRS and LTR. Thus, the GBS sample is developed as a potential matrix matching geological standard for geochemical studies of the Himalayan river sediments as well as other large tropical river systems.