The behavioural characteristics of sediment properties and their implications for sediment fingerprinting as an approach for identifying sediment sources in river basins

Sediment fingerprinting is a technique that is increasingly being used to improve the understanding of sediment dynamics within river basins. At present, one of the main limitations of the technique is the ability to link sediment back to their sources due to the non-conservative nature of many of the sediment properties. The processes that occur between the sediment source locations and the point of collection downstream are not well understood or quantified and currently represent a black-box in the sediment fingerprinting approach. The literature on sediment fingerprinting tends to assume that there is a direct connection between sources and sinks, while much of the broader environmental sedimentology literature identifies that numerous chemical, biological and physical transformations and alterations can occur as sediment moves through the landscape. The focus of this paper is on the processes that drive particle size and organic matter selectivity and biological, geochemical and physical transformations and how understanding these processes can be used to guide sampling protocols, fingerprint selection and data interpretation. The application of statistical approaches without consideration of how unique sediment fingerprints have developed and how robust they are within the environment is a major limitation of many recent studies. This review summarises the current information, identifies areas that need further investigation and provides recommendations for sediment fingerprinting that should be considered for adoption in future studies if the full potential and utility of the approach are to be realised.