3.2. Major ions
Chloride and sulphate were the predominant anions in sampled waters (and
presumably also bicarbonate, which was not measured, yet its
concentrations estimated from the ionic balance approximated the
concentrations of calcium ions, and if recalculated to mass, they were
the main ions in the collected samples, reaching 311 mg
L-1 in P2). Phosphate, nitrate, nitrite and bromide
have only been detected in a few samples each, therefore they are not
presented in graphs (Figure 3). The highest dissolved solid
concentrations have been found in Yedoma-fed creeks (>100
mg/L of chloride and sulphate both), and sulphate was relatively high in
most Kolyma river samples. Among cations, calcium was predominant, at
the average level of 12.4 mg L-1 in the Kolyma river,
while magnesium was usually second, exceeding Ca2+only in P2 sample at 74.2 mg L-1 in the permafrost
cliff creeks (DY; Figure 4). Permafrost-fed creeks exhibited relatively
high concentrations (approx. 50 mg L-1 or more) of all
three cations: Ca2+, Mg2+ and
Na+ (Figure 4). If the ionic water type is defined,
using the [mval] concentrations of major ions amounting to at least
20% of the anion or cation total (Suppl. Mat. 2 ), three groups
of objects emerge: (1) thermokarst lakes and permafrost ice represented
the HCO3-Ca-Mg water type; (2) in the rivers, water
types varied between SO4-HCO3-Ca-Mg,
Ca-Mg-HCO3-SO4 and
Ca-Mg-Na-HCO3-SO4, except sample A2
(SO4-Ca-Mg); (3) permafrost creeks were of
Mg-Ca-Na-HCO3-Cl-SO4 type.