  Disequilibrium species have been used previously to probe the deep water
abundances and the eddy diffusion coefficient for giant planets. In this paper,
we present a diffusion-kinetics code that predicts the abundances of
disequilibrium species in the tropospheres of Jupiter and Saturn with updated
thermodynamic and kinetic data. The dependence on the deep water abundance and
the eddy diffusion coefficient is investigated. We quantified the disagreements
in CO kinetics that comes from using different reaction networks and identified
C$_2$H$_6$ as a useful tracer for the eddy diffusion coefficient. We first
apply a H/P/O reaction network to Jupiter and Saturn's atmospheres and suggest
a new PH$_3$ destruction pathway. New chemical pathways for SiH$_4$ and GeH$_4$
destruction are also suggested, and another AsH$_3$ destruction pathway is
investigated thanks to new thermodynamic and kinetic data. These new models
should enhance the interpretation of the measurement of disequilibrium species
by JIRAM on board Juno and allow disentangling between methods for constraining
the Saturn's deep water abundance with the Saturn entry probes envisaged by
NASA or ESA.
