A review of the defining chemical properties of soda lakes and pans: An assessment on a large geographic scale of Eurasian inland saline surface waters

PLoS One. 2018 Aug 20;13(8):e0202205. doi: 10.1371/journal.pone.0202205. eCollection 2018.

Abstract

The aim of this study is to evaluate the definition of water chemical type, with particular attention to soda brine characteristics by assessing ionic composition and pH values on a large geographic scale and broad salinity (TDS) range of Eurasian inland saline surface waters, in order to rectify the considerable confusion about the exact chemical classification of soda lakes and pans. Data on pH and on the concentration of eight major ions were compiled into a database drawn from Austria, China, Hungary, Kazakhstan, Mongolia, Russia, Serbia, and Turkey. The classification was primarily based on dominant ions exceeding an equivalent percentage of 25 (> 25e%) of the total cations or anions, and the e% rank of dominant ions was also identified. We identified four major types: waters dominated by (1) Na-HCO3 (10.0%), (2) Na-HCO3 + CO3 (31.4%), (3) Na-Cl (45.9%), and (4) Na-SO4 (12.7%), considering only the first ion by e% rank. These major types can be divided into 30 subtypes in the dataset, taking into account the e% rank of all dominant ions. The major and subtypes of soda brine can be divided into "Soda" and "Soda-Saline" types. "Soda type" when Na+ and HCO3- + CO3(2-) are the first in the rank of dominant ions (> 25e%), and "Soda-Saline type" when Na+ is the first in the rank of dominant cations and the sum of HCO3- + CO3(2-) concentration exceeds 25e%, but it is not the first in the rank of dominant anions. Soda-saline type can be considered as a separate evolutionary stage between Soda and Saline types respect to the geochemical interpretation by saturation indexes of brines. The obtained overlapping ranges in distribution demonstrate that a pH measurement alone is not a reliable indicator to classify the permanent alkaline "soda type" and various other types of temporary alkaline waters.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Asia
  • Carbonates / analysis
  • Europe
  • Hydrogen-Ion Concentration
  • Lakes / chemistry*
  • Salinity
  • Sodium Bicarbonate / analysis
  • Sodium Chloride / analysis
  • Sulfates / analysis

Substances

  • Carbonates
  • Sulfates
  • sodium sulfate
  • Sodium Chloride
  • Sodium Bicarbonate

Associated data

  • Dryad/10.5061/dryad.hj400j2

Grants and funding

The data assessment and study was founded by European-financed Hungarian Economic Development and Innovation Operative Programme (GINOP–2.3.2–15–2016–00019) for comprehensive assessment and by Russian Science Foundation (RSF, Project 17-77-10086) for studies in Siberian region. Additional data collection in Mongolia was founded by the support of European Union LIFE11NAT/HU/000924 project.