Elemental composition of grass phytoliths: Environmental control and effect on dissolution
Résumé
Plant phytoliths, which represent the main pool of silica (Si) in the form of hydrous Si oxide, are capable of
providing valuable information on different aspect of environmental issues including paleo-environmental
reconstruction and agricultural sustainability. Phytoliths may have different chemical composition, which, in
turn, affects their preservation in soils ad impacts terrestrial cycle of the occluded elements including micro-
nutrients and environmental toxicants. Yet, in contrast to sizable work devoted to phytoliths formation, disso-
lution and physico-chemical properties, the mechanisms that control total (major and trace) elemental compo-
sition and the impact that various elements exert on phytolith reactivity and preservation in soils remains poorly
known. In order to fil this gap in knowledge, here we combined two different approaches – analytical trace
element geochemistry and experimental physical chemistry. First, we assessed full elemental composition of
phytoliths from different plants via measuring major and trace elements in 9 samples of grasses collected in
northern Eurasia during different seasons, 18 grasses from Siberian regions, and 4 typical Si-concentrating plants
(horsetail, larch, elm and tree fern). We further assessed the dissolution rates of phytoliths exhibiting drastically
different concentrations of trace metals.