11 Monitoring of Groundwater Quality in Poland
249
11.4.2 Lake District Zone
The western part of the lakeland area constitutes the Lower Oder region and Szczecin
Lagoon. The two-ionic water of the HCO 3 –Ca type and three-ionic water of the
HCO 3 –Ca–Mg type prevail here, and they represent high-quality class water. This is
mainly well-insulated groundwater aquifer occurring in the upland area within the
Quaternary formations. In the lowland areas and outwash plains with poor insulation
of the water-bearing level two-ionic and three-ionic waters can be found where apart
from the Ca and Mg ions, there are also chloride, sodium and sulphate ions. The Fe
and Mn ions occur in excessive concentration in the whole area whereas the NH 4
ion occurs in excessive concentrations only locally [14].
In the central part of the lakeland area (the lakeland subregion represented by
the observation wells number I/257/1, II/525/1, II/533/1 and I/388/1) the chemical
composition of the Quaternary and Palaeogene and Neogene aquifers is similar.
Ordinary waters of the HCO 3 –Ca and HCO 3 –Ca–Mg type occur in the greater part
of the area. Locally, in the vicinity of the observation well number II/525/1, the
increased concentration of the chloride ion becomes noticeable, which is probably
connected with anthropogenic pollution. The water of these water-bearing levels
needs simple treatment for the presence of Fe and Mn.
The chemical composition of the Cretaceous aquifer differs from the aforementioned water-bearing levels in terms of increased concentrations of Ca, Cl and Na
ions. Two types of water prevail in the area: HCO 3 –Ca and HCO 3 –Ca–Mg. The
chemical composition of groundwater in this area changes towards ˙
Zuławy Wi´ slane
and the Vistula River Valley, where its mineralization and concentration of chlorides increase reaching its maximum in the area to the south of Bydgoszcz [5]. The
eastern part of the lakeland zone is the basin of the Narew, Pregoła and the Neman
River. Similarly to the remaining part of the Lake District zone, in the majority of
observation wells (II/1239/1, II/1435/1, I/250/2, I/537/1) waters of the HCO 3 –Ca and
HCO 3 –Ca–Mg types occur. These types of groundwater are typical of shallow areas
of intensive exchange. The factors which negatively affect the groundwater quality
are the exceedances of the Fe and Mn ions. In the Cretaceous formations water of
the HCO 3 –Na type locally occurs. According to Michalski [15] and Liszkowska
[16], this type of water represents cryogenic transformed groundwater, by which
they mean water the chemical composition of which has been transformed as a result
of freezing. The occurrence of cryogenic water in this area is a consequence of the
presence of permafrost, the thickness of which during the last glaciation reached up
to 500 m [17].
249
11.4.2 Lake District Zone
The western part of the lakeland area constitutes the Lower Oder region and Szczecin
Lagoon. The two-ionic water of the HCO 3 –Ca type and three-ionic water of the
HCO 3 –Ca–Mg type prevail here, and they represent high-quality class water. This is
mainly well-insulated groundwater aquifer occurring in the upland area within the
Quaternary formations. In the lowland areas and outwash plains with poor insulation
of the water-bearing level two-ionic and three-ionic waters can be found where apart
from the Ca and Mg ions, there are also chloride, sodium and sulphate ions. The Fe
and Mn ions occur in excessive concentration in the whole area whereas the NH 4
ion occurs in excessive concentrations only locally [14].
In the central part of the lakeland area (the lakeland subregion represented by
the observation wells number I/257/1, II/525/1, II/533/1 and I/388/1) the chemical
composition of the Quaternary and Palaeogene and Neogene aquifers is similar.
Ordinary waters of the HCO 3 –Ca and HCO 3 –Ca–Mg type occur in the greater part
of the area. Locally, in the vicinity of the observation well number II/525/1, the
increased concentration of the chloride ion becomes noticeable, which is probably
connected with anthropogenic pollution. The water of these water-bearing levels
needs simple treatment for the presence of Fe and Mn.
The chemical composition of the Cretaceous aquifer differs from the aforementioned water-bearing levels in terms of increased concentrations of Ca, Cl and Na
ions. Two types of water prevail in the area: HCO 3 –Ca and HCO 3 –Ca–Mg. The
chemical composition of groundwater in this area changes towards ˙
Zuławy Wi´ slane
and the Vistula River Valley, where its mineralization and concentration of chlorides increase reaching its maximum in the area to the south of Bydgoszcz [5]. The
eastern part of the lakeland zone is the basin of the Narew, Pregoła and the Neman
River. Similarly to the remaining part of the Lake District zone, in the majority of
observation wells (II/1239/1, II/1435/1, I/250/2, I/537/1) waters of the HCO 3 –Ca and
HCO 3 –Ca–Mg types occur. These types of groundwater are typical of shallow areas
of intensive exchange. The factors which negatively affect the groundwater quality
are the exceedances of the Fe and Mn ions. In the Cretaceous formations water of
the HCO 3 –Na type locally occurs. According to Michalski [15] and Liszkowska
[16], this type of water represents cryogenic transformed groundwater, by which
they mean water the chemical composition of which has been transformed as a result
of freezing. The occurrence of cryogenic water in this area is a consequence of the
presence of permafrost, the thickness of which during the last glaciation reached up
to 500 m [17].