Figure 3

Size distributions of Na⁺ collected at the OUC site in different seasons, (a): Category-A data of OUC samples in the spring of 2013; (b): Category-B data of OUC samples in the spring of 2013; (c): Category-A data of OUC samples in the winter of 2015; (d): Category-B data of OUC samples in the winter of 2015.