Chemical and Physical Properties of Maharlu Salt Lake (Iran) Prior to an Extensive Drought

Aims The ecology of Maharlu Lake is of great importance, especially in relation to the continuous addition of a reasonable volume of municipal and industrial effluents to it. To improve our knowledge about lake’s ecology, mineral nutrients and heavy metal concentrations, among some other physical and chemical factors, are investigated. Materials & Methods 3 stations were selected in the lake and critical factors were measured monthly from January 2000 to December 2001. Main physical and chemical properties included temperature, pH, dissolved oxygen, CO2, conductivity, salinity, dissolved solids, and concentration of major ions, including carbonate and bicarbonate, phosphate, nitrite and nitrate, calcium and total hardness, chloride, and alkalinity, and heavy metals as Co, Cd, Pb, and Hg. Findings Averages of pH, dissolved oxygen, salinity, electrical conductivity, and dissolved CO2 were 7.9, 2.9mgL-1, 290gL-1, 375mscm-1, 342mgL-1, and 63mgL-1, respectively. The highest concentrations of heavy metals were 23μgL-1 for As, 303μgL-1 for Co, 970μgL-1 for Cd, 8510μgL-1 for Pb, and 25μgL-1 for Hg. Conclusion Essential factors of the lake are in accordance with the soil of the catchment area, but they are in many cases altered under local attributes like precipitation, irradiation, evaporation, and deposits, as well as living elements of the lake’s ecological network, as the consequences of activities of bacteria in biological processing of nitrogen and phosphorus, etc. After this research, Maharlu Lake was totally dried up, never filled again. So, the results of this investigation can be regarded as the last record of the lake situation prior to its current complete drought condition.