  The elemental compositions of planets define their chemistry, and could
potentially be used as beacons for their formation location if the elemental
gas and grain ratios of planet birth environments, i.e. protoplanetary disks,
are well understood. In disks, the ratios of volatile elements, such as C/O and
N/O, are regulated by the abundance of the main C, N, O carriers, their ice
binding environment, and the presence of snowlines of major volatiles at
different distances from the central star. We explore the effects of disk
dynamical processes, molecular compositions and abundances, and ice
compositions on the snowline locations of the main C, O and N carriers, and the
C/N/O ratios in gas and dust throughout the disk. The gas-phase N/O ratio
enhancement in the outer disk (exterior to the H2O snowline) exceeds the C/O
ratio enhancement for all reasonable volatile compositions. Ice compositions
and disk dynamics individually change the snowline location of N2, the main
nitrogen carrier, by a factor of 2-3, and when considered together the range of
possible N2 snowline locations is ~11- ~79 AU in a standard disk model.
Observations that anchor snowline locations at different stages of planet
formation are therefore key to develop C/N/O ratios as a probe of planet
formation zones.
