Coupling bioturbation activity to metal (Fe and Mn) profiles in situ

[摘要] The relative contributions that species assemblages, abiotic variables, andtheir interactions with one another make to ecosystem properties arerecognised but are seldom considered simultaneously, within context, and atthe appropriate spatio-temporal scales. Here, we combine fluorescenttime-lapse sediment profile imaging (f-SPI) and diffusion gradient thin gels(DGT) to examine, in situ, the link between an important benthic ecosystem process(bioturbation) and the availability (profiles) of Fe and Mn. Whilst thecombination of these methodologies (fg-SPI) was successful in gatheringhigh-resolution in situ data of bioturbation activity and Fe/Mn profilessimultaneously, we show that the mechanistic basis of how the infaunalcommunity mediate Fe and Mn is difficult to reconcile because of thespatio-temporal differences between particle and porewater mixing. Thismismatch means that the consideration of these mechanistic processes inisolation is likely to limit our interpretative capacity of how infaunalcommunities mediate various biogeochemical processes in the naturalenvironment. Moreover, the combination of multiple technologies, processbased simulation modelling and generalised additive statistical modellingachieved here, emphasises the importance of simultaneously consideringadditional factors that influence benthic chemistry, in particularbioirrigation and tidal flushing of the sediment profile. Our findingshighlight a pressing need to determine how the relative importance ofmultiple abiotic and biotic factors act in concert to alter majorbiogeochemical pathways across a variety of contexts and habitats.

[学科分类] 地球化学与岩石