The Salty Lakes of Ocna Sibiului. Past. Present. Future

At the center of the Transyvanian Plateau lies Ocna Sibiului, with its salt deposits which, in places,  run  up  to  one  thousand  meters  below  the  surface.  The  presence  of  these  deposits has  been favored, due the extraction of salt throughout the years causing the formation of the now famous salt lakes. Due to different environmental conditions, lacustrine cuvettes and water quality differ from one lake  to  another. The  studied  lakes  are  considered  to  be  in  conection  with  the  salt  deposits  exposed through  minig  activities  carried  on  in  different time periods.  Other  lakes  in  the  area  already are isolated from salt deposits due to natural sedimentation proceses. The study adresses the lakes which still  present  a  high  degree of  salinity  and  are  used for  balnear  purposes,  and  present,  due  to  various factors, variation of physical-chemical composition throughout the year. Water samples were collected from  the  main  six  lakes  in  Ocna  Sibiului  (Ocniţa –  Avram  Iancu;  Rândunica;  Negru;  Fără  Fund; Brâncoveanu  and  Gura  Minei). Surveys  were  carried  out  in four  periods  (March-November)  during 2012.Water  temperature,  electrical  conductivity  (at  25°C)  and  pH  were  measured in-situ. The water pH  changed from  a  lake  to  another.  Generally  it  is  within  the  range of  6.78  to  8.8  highlighting  the neutral  to  slightly  alkaline  lake  water.  Salt  lake  water  conductivity  values,  in  the  upper  layers  vary within  a  wide  range,  from  more  than  200  mS cm-1 to 45.7 mS cm-1, with  different  values from the different  lacustrine  units. The  salt  water  lakes are  characterized  by  high  content  of  sodium  and chlorine ions. The other major ions are present in a small amount. This paper aims to compare the past and present evolution, characteristics and environment of these lakes, , and, based on this and current research, to project a vision of their future and how it will affect the lives of future generations living besides them.