Fate of iron (Fe), dissolved organic carbon (DOC) and absorbance (a₄₂₀) along the aquatic continuum under normal wet conditions (panel A) and in a wetter climate (panel B).

<p>When water travels from headwaters to river mouths and passes lakes Fe, DOC and a₄₂₀ all decline (compare <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088104#pone-0088104-g003" target="_blank">Fig. 3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088104#pone-0088104-g004" target="_blank">Fig. 4</a>). It is suggested that a concomitant Fe, DOC and a₄₂₀ decline in surface waters of lakes is a result of Fe-OC complexes that can flocculate and reach bottom waters and sediments (panel A). In a wetter climate with a consequent faster flushing of waters through lakes the settling of Fe-OC complexes towards bottom waters and sediments becomes less efficient and Fe-OC complexes reach downstream waters, where they cause strong declines in a₄₂₀ (panel B). The conceptual figure assumes that Fe-OC complexes mainly originate from soils.