Quantification of chloride ions in brackish water and its application to inquiry learning in high school

We tried to measure quantity of chloride ion in sea water by Mohr method at estuaries of the Wakagawa River and Kinokawa River. From these results, it is clear that the concentrations of chloride ion at estuaries are correlated with ebb and flow of the tide. The maximum of concentrations of chloride ion observed at estuary of the Wakagawa River is 18,560mg L^-1,and this value is similar to ca.19,000mg L^-1 in the Kuroshio Current.
On the other hand, the concentrations of chloride ion observed at estuary of the Kinokawa River are almost smaller than those at estuary of the Wakagawa River. This result is attributable to larger amount of running water in river. Finally, these experiments were applied into practice in high school.