Table 1.

Details on the two selected sampling locations in Central Poland

Site	Location	Type of the salinity source	Geographical coordinates	Cause of salinity
S1	Ciechocinek	natural	N52°53, E18°47°	The periodic flooding by brine (NaCl) transported by a ditch from the graduation towers (previously taken from the natural spring being in contact with Zechstein rock-salt deposits).
S2	Inowrocław	anthropogenic	N52°48, E18°15°	Salt infiltration (mainly CaCl2 and NaCl) from the improperly sealed waste ponds. There are solid and semi-liquid solid industrial waste produced during the manufacturing of the soda ash by the Solvay method.