Figure 4

Geographical distribution of the K+ concentration in the research area from 2015 to 2019. Figure mainly describes the spatial concentration changes of K+ in the research area from 2015 to 2019. (a), (b), (c), (d) and (e) respectively represent the spatial concentration changes of K+ in the research area in 2015, 2016, 2017, 2018 and 2019. Figure was created using ArcGIS [10.2].