The role of vegetation in setting strontium stable isotope ratios in the Critical Zone

At Earth9s surface the stable isotope ratio of strontium (88Sr/86Sr) is predominantly set by biological uptake Sr and its storage in plant litter. This conclusion was reached from a mass balance that independently validated direct determination elemental fluxes between Critical Zone compartments (rock, soil, vegetation, stream water) three field sites located Swiss Alps, US Sierra Nevada, tropical highlands Sri Lanka. These cover gradient erosion rates, which inversely related to residence time solids thereby constituting an “erodosequence”. For eroding landscapes, previous models predicted ratios are rate at secondary form during conversion rock regolith. Counter this expectation we found that, after release primary minerals, partitioned into one fraction taken up plants remainder dissolved flux. The formation weathering products such as clays oxides plays subordinate role determining budget. A fractionation factor for determined each ecosystems average composition bulk counterpart water. factors range ca. ?0.3 ‰ Alps Nevada ?0 Lanka site. That these fingerprints caused biologic preserved means more physically removed litter than recycled. Such removal appears be strongest slowly-eroding site, whereas export streams highest site with fastest rate. There, all returned back solution. short only parent material differ their composition. Our study shows behavior stark contrast metals not affected (for example lithium, mostly solids) or both solid silicon). Strontium signatures offer new opportunity quantify nutrient cycling function environmental ecological parameters.