@article{Weiss:2021:10.1016/j.chemgeo.2021.120271,
author = {Weiss, D and Northover, G and Hanif, M and García-España, E and Vilar, R and Arnold, T and Markovic, T and Wissuwa, M and Delgado, E},
doi = {10.1016/j.chemgeo.2021.120271},
journal = {Chemical Geology},
pages = {1--21},
title = {Isotope fractionation of zinc in the paddy rice soil-water environment and the role of 2’deoxymugineic acid (DMA) as zincophore under Zn limiting conditions},
url = {http://dx.doi.org/10.1016/j.chemgeo.2021.120271},
volume = {577},
year = {2021}
}

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TY  - JOUR
AB  - Non-traditional stable isotope systems are increasingly used to study micronutrient cycling and acquisition in terrestrial ecosystems. We previously proposed for zinc (Zn) a conceptual model linking observed isotope signatures and fractionations to biogeochemical processes occurring in the rice soil environment and we suggested that 2’deoxymugineic acid (DMA) could play an important role for rice during the acquisition of Zn when grown under Zn limiting conditions. This proposition was sustained by the extent and direction of isotope fractionation observed during the complexation of Zn with DMA synthesised in our laboratory. Here we report a new set of experimental data from field and laboratory studies designed to further elucidate the mechanisms controlling Zn isotope fractionation in the rice rhizosphere and the role of DMA. First, we present acidity (pKa) and complexation (logK) constants for DMA with H+ and Zn2+, respectively, using synthetic 2’deoxymugineic acid and show that they are significantly different from previously published data using isolates from plants. Our new set of thermodynamic data allows for a more accurate calculation of the formation of ZnDMA complexes over pH ranges typically found in the rhizosphere of flooded lowland rice soils and in rice plant compartments (xylem, phloem). We show that at pH > 6.5, Zn is fully complexed by DMA and at pH <4.5 fully dissociated. This has important implications, i.e. that in alkaline paddy soils, DMA can strip Zn from soil solids (organic and inorganic) and that ZnDMA complexes are stable at the root interface if the pH is alkaline and in the phloem and xylem of the rice shoot. Second, we present a new set of Zn isotope data in rice grown in alkaline soils with low Zn availability with and without Zn addition. We used two genotypes not tested to date, i.e. A69–1, tolerant to low Zn supply, and IR26, sensitive to low Zn supply. We confirm previous findings that, in contrast to obse
AU  - Weiss,D
AU  - Northover,G
AU  - Hanif,M
AU  - García-España,E
AU  - Vilar,R
AU  - Arnold,T
AU  - Markovic,T
AU  - Wissuwa,M
AU  - Delgado,E
DO  - 10.1016/j.chemgeo.2021.120271
EP  - 21
PY  - 2021///
SN  - 0009-2541
SP  - 1
TI  - Isotope fractionation of zinc in the paddy rice soil-water environment and the role of 2’deoxymugineic acid (DMA) as zincophore under Zn limiting conditions
T2  - Chemical Geology
UR  - http://dx.doi.org/10.1016/j.chemgeo.2021.120271
UR  - https://www.sciencedirect.com/science/article/pii/S0009254121002151?via%3Dihub
UR  - http://hdl.handle.net/10044/1/99040
VL  - 577
ER  - 

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