258
high HCO 3
−
ions, reducing conditions, and almost neutral pH, the reductive dissolution of Mg oxides will mobilize As in water (Quevauviller et al. 2009). The third
factor F3 (NO 3
−
, NO 2
−
, Mg, and Cu) positively correlates NO 3 , NO 2 , Mg, and Cu
and associates ions that are affected by the reduction processes in groundwater. The
first step of the denitrification process is the reduction of NO 3
−
to NO 2
−
. The presence of Mg and Cu in this factor and the positive correlation with NO 3
−
and NO 2
−
indicate to the reduction of these elements in groundwater. The fifth factor F5 (NH 4
+
,
PO 4
3−
, and Fe) associates ions which are related to the use of fertilizers.
8.4 Conclusion
The quality of groundwater situated under agriculture land was investigated in this
study regarding major and minor components, some heavy metals, and trace elements. The descriptive analysis showed that groundwater in the Strumica region is
not uniform but differs considerably in major and minor component concentrations.
Groundwater samples were considered in terms of their depth and processed as
shallow (<70 m) and deep (>70 m) groundwater. Higher median values were
observed for HCO 3
−
, NO 3
−
, SO 4
2−
, Cl
−
, Ca, Mg, and K concentrations in shallow
groundwater, while Fe, Mn, Na, PO 4
3−
, and NH 4
+
showed greater concentrations in
deep groundwater. Welch’s t-test followed by power analysis was used to investigate
differences between cations and anions in shallow and deep groundwater. The result
indicates significant differences in NH 4
+
, PO 4
3−
, Fe, Mn, As, Ba, Ti, and Zn concentrations. Piper diagram plotted to identify groundwater chemistry showed that the
majority of groundwater falls under the rock dominance category and belongs to the
Ca-HCO 3 water type suggesting that carbonate rock watering plays a significant
role in the groundwater chemistry of the Strumica region. High HCO 3
−
(med
272 mg/l), As (med 28 μg/l), Fe (med 480 μg/l), and Mg (med 12.2 μg/l) concentrations, as well as low PO 4
3−
(med 0.52 mg/l) and SO 4
2−
(med 18.2 mg/l) concentrations and pH 7–8 in samples with low nitrate concentrations (<10 mg/l), suggest the
presence of reductive environment which contribute in the process of denitrification
at almost 65% of investigated groundwater samples. Almost 35% of investigated
groundwater samples showed As concentration greater than 10 μg/l from which
16% have concentration greater than 50 μg/l with a maximum concentration of
177 μg/l. Reducing environment present in the groundwater of the Strumica region;
high Fe, Mg, and HCO 3
−
; and low SO 4
2−
and NO 3
−
content suggest that reductive
dissolution is a major mechanism by which arsenic is released into the groundwater.
Factor analysis performed to access of investigated major and minor components in
groundwater of the Strumica region identify four significant factors. The amount of
Cl
−
, SO 4
2−
, Na, K, and B in groundwater is attributed to the rainwater leaching
through the soil. The amount of HCO 3
−
, Ca, As, and Mg is attributed to the main
hydrogeochemical reactions that exist in groundwater of the investigated region.
The amount of NO 3
−
, NO 2
−
, Mg, and Cu are related to the reduction processes that
B. Kovacevik et al.
high HCO 3
−
ions, reducing conditions, and almost neutral pH, the reductive dissolution of Mg oxides will mobilize As in water (Quevauviller et al. 2009). The third
factor F3 (NO 3
−
, NO 2
−
, Mg, and Cu) positively correlates NO 3 , NO 2 , Mg, and Cu
and associates ions that are affected by the reduction processes in groundwater. The
first step of the denitrification process is the reduction of NO 3
−
to NO 2
−
. The presence of Mg and Cu in this factor and the positive correlation with NO 3
−
and NO 2
−
indicate to the reduction of these elements in groundwater. The fifth factor F5 (NH 4
+
,
PO 4
3−
, and Fe) associates ions which are related to the use of fertilizers.
8.4 Conclusion
The quality of groundwater situated under agriculture land was investigated in this
study regarding major and minor components, some heavy metals, and trace elements. The descriptive analysis showed that groundwater in the Strumica region is
not uniform but differs considerably in major and minor component concentrations.
Groundwater samples were considered in terms of their depth and processed as
shallow (<70 m) and deep (>70 m) groundwater. Higher median values were
observed for HCO 3
−
, NO 3
−
, SO 4
2−
, Cl
−
, Ca, Mg, and K concentrations in shallow
groundwater, while Fe, Mn, Na, PO 4
3−
, and NH 4
+
showed greater concentrations in
deep groundwater. Welch’s t-test followed by power analysis was used to investigate
differences between cations and anions in shallow and deep groundwater. The result
indicates significant differences in NH 4
+
, PO 4
3−
, Fe, Mn, As, Ba, Ti, and Zn concentrations. Piper diagram plotted to identify groundwater chemistry showed that the
majority of groundwater falls under the rock dominance category and belongs to the
Ca-HCO 3 water type suggesting that carbonate rock watering plays a significant
role in the groundwater chemistry of the Strumica region. High HCO 3
−
(med
272 mg/l), As (med 28 μg/l), Fe (med 480 μg/l), and Mg (med 12.2 μg/l) concentrations, as well as low PO 4
3−
(med 0.52 mg/l) and SO 4
2−
(med 18.2 mg/l) concentrations and pH 7–8 in samples with low nitrate concentrations (<10 mg/l), suggest the
presence of reductive environment which contribute in the process of denitrification
at almost 65% of investigated groundwater samples. Almost 35% of investigated
groundwater samples showed As concentration greater than 10 μg/l from which
16% have concentration greater than 50 μg/l with a maximum concentration of
177 μg/l. Reducing environment present in the groundwater of the Strumica region;
high Fe, Mg, and HCO 3
−
; and low SO 4
2−
and NO 3
−
content suggest that reductive
dissolution is a major mechanism by which arsenic is released into the groundwater.
Factor analysis performed to access of investigated major and minor components in
groundwater of the Strumica region identify four significant factors. The amount of
Cl
−
, SO 4
2−
, Na, K, and B in groundwater is attributed to the rainwater leaching
through the soil. The amount of HCO 3
−
, Ca, As, and Mg is attributed to the main
hydrogeochemical reactions that exist in groundwater of the investigated region.
The amount of NO 3
−
, NO 2
−
, Mg, and Cu are related to the reduction processes that
B. Kovacevik et al.