A New Approach of Using Multiple Composite Fingerprints to Apportion Sediment Sources

摘要

Sediment source fingerprinting provides an essential means for estimating sediment source contributions, which are needed not only for soil conservation planning but also for erosion model evaluation and refinement. A single optimum composite fingerprint has been widely used in the literature to estimate sediment provenance. The objectives of this work are to: (1) verify whether an optimum composite fingerprint exists, (2) present a new direction of using multiple composite fingerprints to improve the accuracy and reliability of source contribution estimation, and (3) evaluate and compare the new approach and the optimum composite fingerprint approach using a synthetic sediment mixture. We collected 50 surface samples from overland flow areas in a 15.6 km2 watershed (Figure 1), 28 subsoil samples from gully banks, and 8 sediment samples at the watershed outlet. We then analyzed 31 elements using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and a Macro Analyzer. The results show that tracerselection greatly impacts the estimated source contributions. The optimum composite fingerprint may not exist, or at least cannot be identified simply based on a tracer's ability to discriminate sources because of the lack of correlation between the tracer's ability to discriminate and its rigor in estimating source contributions.