253
and 614 mg/l with a median value of 24.4 mg/l indicating low pollution. Around
10% of investigated samples showed chloride concentrations greater than 70 mg/l
found mostly in shallow groundwater. Although Welch’s t-test confirms statistically
significant differences between chloride concentrations in shallow and deep groundwater, the power analysis was equal to zero, so this result was rejected, and it is
assumed that there are no statistically significant differences between chloride concentrations in shallow and deep groundwater.
Magnesium is a common element in groundwater and together with other alkali
earth metals is responsible for water hardness. It may end up in groundwater from
many different sources like the chemical industry of plastics, fertilizers, cattle feed,
wastewater, and water-rock interactions. Numerous minerals contain Mg like dolomite (CaMg(CO 3 ) 2 ) and magnesite (MgCO 3 ). The only oxidation state significant in
water chemistry is Mg
2+
. The concentration of Mg in investigated groundwater
ranged between 1.1 and 96 mg/l with a median of 9.7 mg/l. The investigations of
Mg concentrations in groundwater from different areas showed concentrations in
the range from 8.5 to 51,500 mg/l (Hem 1985). The investigations of Pandian and
Sankar (2007) of groundwater quality in Vaippar River basin, Tamil Nadu, an area
underlain by Precambrian rocks like charnockites, hornblende-biotite gneisses,
granite, and crystalline limestones, as well as alluvial deposits along the river basin,
showed Mg concentrations in the range of 21.5–92.8 mg/l in post-monsoon and
35.02–91.4 mg/l in the pre-monsoon period. In this study, Welch’s t-test showed
statistically significant differences between Mg concentrations in shallow and deep
groundwater, but the power of the analysis was zero, so this outcome is not accepted,
and it is assumed that there is no difference between shallow and deep groundwater
regarding Mg concentrations in the investigated region.
Although Mg is an essential element, higher concentrations in irrigated water
may be harmful to the plants. The harmful effect of Mg in irrigated water is estimated by the magnesium hazard indices (MH) (Szabolcs and Darab 1964). Water
having values greater than 50 is considered unsuitable for irrigation. Around 7% of
investigated groundwater samples are unsuitable for irrigation mostly located in the
area of the village Dobreici in the northwest part of the Strumica valley.
The orthophosphate ion is more luckily to be present in groundwater than other
phosphorous ions. Phosphate can be derived in groundwater from different sources
like fertilizers, domestic and industrial sewage effluents, and detergents, but since
phosphates are not very mobile in soils or sediment, its presence in groundwater is
prescribed mostly to the water interactions with phosphate-bearing minerals like
apatite and brushite (CaHPO 4
.
2H 2 O). Concentrations in investigated groundwater
were low and range between less than 0.01 and 7.8 mg/l with a median of 0.18 mg/l.
The most common form of iron in groundwater is the ferrous ion Fe
2+
. Iron concentrations of 1–10 mg/l in groundwater are common for many areas. Sources of
iron in groundwater are fertilizers, industry, and mineralization. Igneous rock minerals high in iron content include the pyroxenes, amphiboles, biotite, magnetite,
and, especially, the nesosilicate olivine. When these minerals react with groundwater, the released iron is reprecipitated. In reducing conditions and high sulfur content, ferrous polysulfides may be formed. If the sulfur is less abundant, then the
8 Groundwater Pollution Under the Intensive Agriculture Production
and 614 mg/l with a median value of 24.4 mg/l indicating low pollution. Around
10% of investigated samples showed chloride concentrations greater than 70 mg/l
found mostly in shallow groundwater. Although Welch’s t-test confirms statistically
significant differences between chloride concentrations in shallow and deep groundwater, the power analysis was equal to zero, so this result was rejected, and it is
assumed that there are no statistically significant differences between chloride concentrations in shallow and deep groundwater.
Magnesium is a common element in groundwater and together with other alkali
earth metals is responsible for water hardness. It may end up in groundwater from
many different sources like the chemical industry of plastics, fertilizers, cattle feed,
wastewater, and water-rock interactions. Numerous minerals contain Mg like dolomite (CaMg(CO 3 ) 2 ) and magnesite (MgCO 3 ). The only oxidation state significant in
water chemistry is Mg
2+
. The concentration of Mg in investigated groundwater
ranged between 1.1 and 96 mg/l with a median of 9.7 mg/l. The investigations of
Mg concentrations in groundwater from different areas showed concentrations in
the range from 8.5 to 51,500 mg/l (Hem 1985). The investigations of Pandian and
Sankar (2007) of groundwater quality in Vaippar River basin, Tamil Nadu, an area
underlain by Precambrian rocks like charnockites, hornblende-biotite gneisses,
granite, and crystalline limestones, as well as alluvial deposits along the river basin,
showed Mg concentrations in the range of 21.5–92.8 mg/l in post-monsoon and
35.02–91.4 mg/l in the pre-monsoon period. In this study, Welch’s t-test showed
statistically significant differences between Mg concentrations in shallow and deep
groundwater, but the power of the analysis was zero, so this outcome is not accepted,
and it is assumed that there is no difference between shallow and deep groundwater
regarding Mg concentrations in the investigated region.
Although Mg is an essential element, higher concentrations in irrigated water
may be harmful to the plants. The harmful effect of Mg in irrigated water is estimated by the magnesium hazard indices (MH) (Szabolcs and Darab 1964). Water
having values greater than 50 is considered unsuitable for irrigation. Around 7% of
investigated groundwater samples are unsuitable for irrigation mostly located in the
area of the village Dobreici in the northwest part of the Strumica valley.
The orthophosphate ion is more luckily to be present in groundwater than other
phosphorous ions. Phosphate can be derived in groundwater from different sources
like fertilizers, domestic and industrial sewage effluents, and detergents, but since
phosphates are not very mobile in soils or sediment, its presence in groundwater is
prescribed mostly to the water interactions with phosphate-bearing minerals like
apatite and brushite (CaHPO 4
.
2H 2 O). Concentrations in investigated groundwater
were low and range between less than 0.01 and 7.8 mg/l with a median of 0.18 mg/l.
The most common form of iron in groundwater is the ferrous ion Fe
2+
. Iron concentrations of 1–10 mg/l in groundwater are common for many areas. Sources of
iron in groundwater are fertilizers, industry, and mineralization. Igneous rock minerals high in iron content include the pyroxenes, amphiboles, biotite, magnetite,
and, especially, the nesosilicate olivine. When these minerals react with groundwater, the released iron is reprecipitated. In reducing conditions and high sulfur content, ferrous polysulfides may be formed. If the sulfur is less abundant, then the
8 Groundwater Pollution Under the Intensive Agriculture Production