Quantifying Fine-Sediment Sources in Primary and Selectively Logged Rainforest Catchments Using Geochemical Tracers

Abstract

Detailed information on post-logging sediment dynamics in tropical catchments is required for modelling downstream impacts on communities and ecosystems. Sediment tracing methods, which are potentially useful in extending to the large catchment scale and longer time scales, are tested in primary and selectively logged rainforest catchments of Sabah, Borneo. Selected nutrient (P and N) and trace metal (Ni and Zn) concentrations are shown to discriminate surface, shallow subsurface and deep subsurface sediment sources. Analysis of channel-stored fine-sediment samples and use of an unmixing model allow the relative importance of these vertical sediment sources to be estimated and erosion processes to be inferred for catchments of contrasting size.

Identifying subsoil sediment sources with carbon and nitrogen stable isotope ratios

“…Additional source sampling would likely reduce the bias of these three samples resulting in significant discrimination between channel and grazing sources. In two of the three catchments, TOC and/or TN significantly discriminated between surface and subsoil sources, one catchment less than anticipated based on the general analysis of TOC and TN in sediment tracing research (Carter et al, 2003;Blake et al, 2006;Owens et al, 2006;Collins et al, 2010). Likewise, δ 13 C provided varied source discrimination.…”

Pipeflow suspended sediment dynamics and their contribution to stream sediment budgets in small rainforest catchments, Sabah, Malaysia

“…The applicability of each property varies between different environmental situations (Collins et al, 2001;Royall, 2001;Collins and Walling, 2002). This exploratory investigation, which forms part of a wider sediment fingerprinting study using a range of sediment properties and a composite-component approach Blake et al, submitted for publication), uses organic carbon content (which is preferentially contained in surface soil relative to the subsoil) to differentiate between surface and subsurface sediment sources. Pipeflow suspended sediment samples were collected from bottle-traps fixed in front of pipe outlets in W3 and from sediment deposited behind the weirs in W7.…”

Testing the sensitivity of a multivariate mixing model using geochemical fingerprints with artificial mixtures

“…Smith et al, 2013;Owens et al, 2016) and explored the potential of fingerprinting tracers like geochemistry, fallout radionuclides, magnetic susceptibility or colour properties (e.g. Collins and Walling, 2002;Blake et al, 2006Blake et al, , 2012Gellis and Noe, 2013;Taylor et al, 2013;Alewell et al, 2014;Navas et al, 2014;Barthod et al, 2015). Recent studies have examined other promising new tracers such as compound specific stable isotope traces (e.g.…”