252
in deep groundwater was 2.4 mg/l. According to Annex 3 of the Groundwater
Directive 2006/118/EC, only five EU member states established a threshold value
(TV) for Mn probably because it is relatively nontoxic and essential for humans and
animals. Bulgaria, France, and Spain set a TV of 0.5 mg/l, Poland set a TV of
1 mg/l, and Slovak set a TV of 0.027–0.2 mg/l. This naturally occurring element is
ubiquitous in the environment and found in soils, sediments, surface water, and
groundwater. It can exist in 11 oxidative states from which the most environmentally and biologically important are Mn
2+
, Mn
4+
, and Mn
7+
(US EPA 1994).
Manganese in groundwater may originate from weathering of manganese-bearing
minerals and rocks, from rainfall percolating through soils, and industry. The concentration and chemical behavior of Mn in groundwater are controlled mainly by
the pH and the redox conditions in groundwater. Acidic and reduced groundwater
conditions contribute to greater Mn concentrations. Concentrations up to 1300 μg/l
in neutral groundwater and 9600 μg/l in acidic groundwater have been reported by
ATSDR (2000). In agriculture, manganese compounds are used in fertilizers and
fungicides and as livestock feeding supplements (HSDB 2001).
Sodium in groundwater may originate from rainwater, saltwater intrusion, sewage effluent, and naturally from water-rock interactions or simply the long residence
time of water in the aquifer. Sodium is more abundant than potassium in igneous
rock but less abundant in sedimentary rocks. Sodium in groundwater shows no
important reactions of precipitation that may lead to lowering its concentrations in
groundwater such is the carbonate precipitations which control the concentrations
of Ca. Sodium can be adsorbed by the clay particles but generally much weaker than
divalent ions. During the cation exchange processes in groundwater, divalent ions
may be extracted and replaced with monovalent such as Na
+
. Concentrations of
sodium in the investigated groundwater ranged from 1.39 to 35.86 mg/l with a
median of 6 mg/l. Literature data for Na concentration in groundwater situated
under the irrigated land showed substantially higher values especially in areas near
the saltwater.
The negative effect of Na in irrigated water was estimated by sodium adsorption
ratio (SAR) (Richards 1954). The obtained result showed very low values (med
0.28 mg/l) indicating that no hazard from sodium is expected regarding soil permeability if investigated groundwater is used for irrigation.
Chlorine can occur in various oxidation states from Cl
−
to Cl
+7
, but the chloride
form has major significance in water. Concentrations reported in the literature
data ranged from less than 1 mg/l to more than 200,000 mg/l (Feth 1981). Chloride
in groundwater may originate from different sources such as rainwater leaching,
saltwater intrusion, domestic and industrial waste discharges, municipal effluents,
and sedimentary water-rock interactions. Chloride-bearing minerals occur in
igneous rocks like feldspathoid sodalite – Na 8 [Cl 2 (AISiO 4 ) 6 ] – and apatite
[Ca 10 (PO 4 ) 6 Cl 2 ], but more important sources are associated with sedimentary
rocks like shale.
Concentrations up to 70 mg/l are considered safe in groundwater, while concentrations greater than 350 mg/l may cause severe problems in plant growth (As et al.
2007). Chloride concentration in the investigated groundwater ranged between 4.2
B. Kovacevik et al.
in deep groundwater was 2.4 mg/l. According to Annex 3 of the Groundwater
Directive 2006/118/EC, only five EU member states established a threshold value
(TV) for Mn probably because it is relatively nontoxic and essential for humans and
animals. Bulgaria, France, and Spain set a TV of 0.5 mg/l, Poland set a TV of
1 mg/l, and Slovak set a TV of 0.027–0.2 mg/l. This naturally occurring element is
ubiquitous in the environment and found in soils, sediments, surface water, and
groundwater. It can exist in 11 oxidative states from which the most environmentally and biologically important are Mn
2+
, Mn
4+
, and Mn
7+
(US EPA 1994).
Manganese in groundwater may originate from weathering of manganese-bearing
minerals and rocks, from rainfall percolating through soils, and industry. The concentration and chemical behavior of Mn in groundwater are controlled mainly by
the pH and the redox conditions in groundwater. Acidic and reduced groundwater
conditions contribute to greater Mn concentrations. Concentrations up to 1300 μg/l
in neutral groundwater and 9600 μg/l in acidic groundwater have been reported by
ATSDR (2000). In agriculture, manganese compounds are used in fertilizers and
fungicides and as livestock feeding supplements (HSDB 2001).
Sodium in groundwater may originate from rainwater, saltwater intrusion, sewage effluent, and naturally from water-rock interactions or simply the long residence
time of water in the aquifer. Sodium is more abundant than potassium in igneous
rock but less abundant in sedimentary rocks. Sodium in groundwater shows no
important reactions of precipitation that may lead to lowering its concentrations in
groundwater such is the carbonate precipitations which control the concentrations
of Ca. Sodium can be adsorbed by the clay particles but generally much weaker than
divalent ions. During the cation exchange processes in groundwater, divalent ions
may be extracted and replaced with monovalent such as Na
+
. Concentrations of
sodium in the investigated groundwater ranged from 1.39 to 35.86 mg/l with a
median of 6 mg/l. Literature data for Na concentration in groundwater situated
under the irrigated land showed substantially higher values especially in areas near
the saltwater.
The negative effect of Na in irrigated water was estimated by sodium adsorption
ratio (SAR) (Richards 1954). The obtained result showed very low values (med
0.28 mg/l) indicating that no hazard from sodium is expected regarding soil permeability if investigated groundwater is used for irrigation.
Chlorine can occur in various oxidation states from Cl
−
to Cl
+7
, but the chloride
form has major significance in water. Concentrations reported in the literature
data ranged from less than 1 mg/l to more than 200,000 mg/l (Feth 1981). Chloride
in groundwater may originate from different sources such as rainwater leaching,
saltwater intrusion, domestic and industrial waste discharges, municipal effluents,
and sedimentary water-rock interactions. Chloride-bearing minerals occur in
igneous rocks like feldspathoid sodalite – Na 8 [Cl 2 (AISiO 4 ) 6 ] – and apatite
[Ca 10 (PO 4 ) 6 Cl 2 ], but more important sources are associated with sedimentary
rocks like shale.
Concentrations up to 70 mg/l are considered safe in groundwater, while concentrations greater than 350 mg/l may cause severe problems in plant growth (As et al.
2007). Chloride concentration in the investigated groundwater ranged between 4.2
B. Kovacevik et al.