254
siderite (FeCO 3 ) is most likely to occur. The activities in the biosphere may also
influence iron concentrations in groundwater since microorganisms are commonly
involved in iron oxidation and reduction processes. Investigated groundwater have
iron concentrations in the range from less than 0.05–3166 μg/l with a median of
69.8 μg/l. Statistically, significant differences are observed between Fe concentrations in shallow and deep groundwater (Table 8.4) with median values of 57.8 μg/l
and 161 μg/l, respectively.
Potassium in groundwater may originate from agriculture activities mainly fertilizer application, rainwater, and organic matter in soil, but the considerable amount
may be released from igneous and metamorphic rocks like silicate minerals, orthoclase, microcline, hornblende, muscovite, and biotite. It is less common in igneous
rock than sodium but more common in all the sedimentary rocks. It is assumed that
potassium concentrations in groundwater are low because of the high degree of
stability of potassium-bearing aluminosilicate minerals. Generally, the potassium
ion is adsorbed less strong than sodium ion in ion exchange reactions mainly
because it is larger, but in illite, it is incorporated in the free space between the crystal layers and thus difficult to be removed by future ion exchange interactions.
Concentrations of potassium in investigated groundwater ranged between 0.7 and
354 μg/l with a low median value of 5.4 μg/l. No significant differences were
observed between potassium concentrations in shallow and deep groundwater.
Piper diagram was used to identify major hydrogeochemical processes in the
groundwater of the investigated region. For that purpose, the concentrations of
major cations like Ca, Mg, Na, and K and major anions like CO 3
2−
, HCO 3
−
, Cl
−
, and
SO 4
2−
were expressed in meq/l and normalized to the percentage of the individual
cation/anion concentration relative to the total cation/anion concentration, respectively. Piper diagram was plotted using the statistical program Grapher 16.2.354
(2020). The result showed that 91.30% of the total 207 investigated samples belong
to the CaHCO 3 water type suggesting that carbonate rock watering plays a significant role in the groundwater chemistry of the Strumica region. The remaining 8.7%
of the investigated samples belong to the Ca-Mg-Cl and Na-HCO 3 type of water
(Fig. 8.2). Such hydrological characteristics of the groundwater are reflected from
the geological formations of the investigated area. Carbonates are present in many
different types of rock. Quaternary alluvial and Neogene clastitic sediments,
Paleozoic shales, Proterozoic gneisses, and magmatic rock are common for the
region of Strumica (Čančalova et al. 2017). Since calcium is a major constituent of
many common rock minerals and the most abundant alkaline-earth metal, it appears
as a major component of the solutes in most natural water.
8.3.1.2 Minor Components
Minor constituents in groundwater generally occur in concentrations lower than
1 mg/l. From the descriptive statistical analysis of the investigated minor constituents given in Table 8.3, it can be seen that minor components also occur in a wide
range of concentrations indicating that groundwater in the investigated region is
B. Kovacevik et al.
siderite (FeCO 3 ) is most likely to occur. The activities in the biosphere may also
influence iron concentrations in groundwater since microorganisms are commonly
involved in iron oxidation and reduction processes. Investigated groundwater have
iron concentrations in the range from less than 0.05–3166 μg/l with a median of
69.8 μg/l. Statistically, significant differences are observed between Fe concentrations in shallow and deep groundwater (Table 8.4) with median values of 57.8 μg/l
and 161 μg/l, respectively.
Potassium in groundwater may originate from agriculture activities mainly fertilizer application, rainwater, and organic matter in soil, but the considerable amount
may be released from igneous and metamorphic rocks like silicate minerals, orthoclase, microcline, hornblende, muscovite, and biotite. It is less common in igneous
rock than sodium but more common in all the sedimentary rocks. It is assumed that
potassium concentrations in groundwater are low because of the high degree of
stability of potassium-bearing aluminosilicate minerals. Generally, the potassium
ion is adsorbed less strong than sodium ion in ion exchange reactions mainly
because it is larger, but in illite, it is incorporated in the free space between the crystal layers and thus difficult to be removed by future ion exchange interactions.
Concentrations of potassium in investigated groundwater ranged between 0.7 and
354 μg/l with a low median value of 5.4 μg/l. No significant differences were
observed between potassium concentrations in shallow and deep groundwater.
Piper diagram was used to identify major hydrogeochemical processes in the
groundwater of the investigated region. For that purpose, the concentrations of
major cations like Ca, Mg, Na, and K and major anions like CO 3
2−
, HCO 3
−
, Cl
−
, and
SO 4
2−
were expressed in meq/l and normalized to the percentage of the individual
cation/anion concentration relative to the total cation/anion concentration, respectively. Piper diagram was plotted using the statistical program Grapher 16.2.354
(2020). The result showed that 91.30% of the total 207 investigated samples belong
to the CaHCO 3 water type suggesting that carbonate rock watering plays a significant role in the groundwater chemistry of the Strumica region. The remaining 8.7%
of the investigated samples belong to the Ca-Mg-Cl and Na-HCO 3 type of water
(Fig. 8.2). Such hydrological characteristics of the groundwater are reflected from
the geological formations of the investigated area. Carbonates are present in many
different types of rock. Quaternary alluvial and Neogene clastitic sediments,
Paleozoic shales, Proterozoic gneisses, and magmatic rock are common for the
region of Strumica (Čančalova et al. 2017). Since calcium is a major constituent of
many common rock minerals and the most abundant alkaline-earth metal, it appears
as a major component of the solutes in most natural water.
8.3.1.2 Minor Components
Minor constituents in groundwater generally occur in concentrations lower than
1 mg/l. From the descriptive statistical analysis of the investigated minor constituents given in Table 8.3, it can be seen that minor components also occur in a wide
range of concentrations indicating that groundwater in the investigated region is
B. Kovacevik et al.