Figure 4

Scatter plots of 224Ra versus (a) DIN concentrations and (b) salinities in the coasts of Tongyeong (A region) and Yeongdeok (B region) during the summers of 2014, 2016, and 2017. The solid and dashed lines represent the relationships between DIN and 224Ra concentrations in the surface waters of A region and subsurface waters of B region, respectively. The red open-circled stations denote the center of the red-tide patches.