Stable calcium isotope speciation and calcium oxalate production within beech tree (Fagus sylvatica L.) organs

BORRELLI, N.; CHABAUX, F.; ERTLEN, D.; OSTERRIETH. M; SCHMITT, A-D; GANGLOFF, S.

BIOGEOCHEMISTRY

SPRINGER

Lugar: Berlin; Año: 2018 vol. 137 p. 197 - 217

0168-2563

In this study, we linked Ca speciation with isotope composition in plants. To do this, we performed leachate experiments to access the soluble Ca, structurally bound Ca and insoluble Ca (i.e., water andweak acid resistant) within beech tree organs (Fagus sylvatica L.). Ca isotopic measurements were combined with infrared spectroscopy and calcium oxalate biomineralization identification. The results from ourstudy indicate that bark and leaves are the most enriched in monohydrated calcium oxalate crystals (whewellite), which are observable in parenchyma and sclerenchyma tissues, whereas roots and wood are enriched in structurally bound Ca. Our leaching experiments also show decreasing d44/40Ca isotopic signatures in the order of soluble Ca[structurallybound Ca[insoluble Ca. This finding implies that because leaves degrade faster than wooden organs and because Ca linked to pectate decomposes faster than Ca linked to oxalate crystals, differential Ca isotopicsignatures are expected to be observed during litter degradation.