Aquatic sediments represent a possibly significant sink of soluble inorganic elements/pollutants (metals, metalloids and rare earth elements) in ecosystems. Bioturbation/bioirrigation was shown to affect the remobilization of some elements where others seem to be unaffected. In view of these contrasting results, the effect of bioturbation/bioirrigation was examined using the invertebrate Chironomus plumosus in a laboratory experiment for a broad range (18) of elements. The experiments revealed an impact of invertebrate bioturbation/bioirrigation on elemental remobilization depending on chemical characteristics of the element ranging from strong influence to influence only at start when the larvae dig into the sediments. Three different types of remobilization were found: (i) element mobilization highly influenced by bioturbation/bioirrigation (DOC, N, Mg, Ca, Sr, Mo and U), (ii) strong element mobilization by bioturbation/bioirrigation at the start of the experiment when the larvae dig into the sediments and afterwards strong decrease, but to higher levels compared to values of treatments without invertebrate impact (Mn, Ni, As, Cd and Cs), and (iii) strong element mobilization by bioturbation/bioirrigation at start when the larvae dig into the sediments and afterwards strong decrease to levels found in treatments without invertebrate impact (Al, Fe, Co, Cu, Zn and Ce). During the experiment a distinct accumulation of most of the elements in C. plumosus was found, where they were not so much bound to the outer surface of C. plumosus but more within the gut system including food and feces. Hence, bioturbation/bioirrigation is certainly a main process controlling mobilization of elements from sediments.
Keywords: Bioaccumulation; DOC; Macrozoobenthos; Mining; Nutrients; Wetland.
Copyright © 2014 Elsevier Ltd. All rights reserved.