Separating Biogenic and Adsorbed Pools of Silicon in Sediments Using Bayesian Inference

There are several potentially mobile pools of silicon in sediment, e.g. biogenic Si (BSi), dissolved Si and adsorbed Si (AdSi) which makes the studying of a single pool very difficult because of the interference caused by other Si pools. In order to evaluate the impact that different Si pools have on the Si cycle of water ecosystems, it is important to have reliable estimates of the pool sizes. The objective of this study was to estimate the joint concentration distributions of two pools, AdSi and BSi, in, of a small catchment area in southern Finland. The potential correlation between BSi and AdSi was studied to find out if the AdSi pool can be inferred from the total pool (BSi + AdSi). The potential error caused by simultaneous extraction of AdSi in BSi determinations was also investigated. Because all extraction methods include variability due to measurement imprecision and inter-sample variation, the different sources of variation were explicitly separated to be able to infer the underlying true variation of AdSi and BSi within the study area. We have utilized Bayesian inference for this task.