Sample location and concentration data were loaded into ArcGIS
(version 10.2.1). The data were mapped onto a satellite image base
map with 0.60 m resolution (ESRI, 2014). Elevation contours were
derived using Digital Terrain Elevation Data, Level 0, which has a postspacing
of 30 arc sec or ca. 900 m (DTED® NIMA, 1990). Political boundaries
(township and village) were obtained from the Myanmar Information
Management Unit (MIMU GIS Datasets, 2013)