98
J. Dawidek et al.
floodplain lakes are determined by the supplying waters of the own catchment. The
quality of lake waters is then determined by atmospheric precipitation, surface and
underground inflow (hypodermic and from a deeper groundwater table). In turn, the
flooding is an important but only cyclical episode in flood ecosystems, during which
lakes are only the recesses of submerged flood terraces [41]. General hydrochemical
relationships resulting from the cycle of successive potamophases and limnophases
and their effect on the quality of valley waters can be expressed with the β index. It
is the ratio of Ca
2+ cation concentration to the sum of Cl
− and SO 4
2− anions concentrations [42]. Calcium, as a product of calcium carbonate dissociation processes, is
treated as a geogenic ion, typical for the natural environment with a significant share
of carbonate sediments. Sulfates and chlorides, being good migrants, are an indicator
of the degree of anthropogenic transformation of the environment. The percentage
quotient of the limnic and fluvial index β
F =
β lakes
β rivers
is the basis for determining
the similarity or difference in the quality of these two environments. On this basis,
the following groups of lakes can be distinguished:
Minor – lakes with a low F-value. The waters of these lakes have a higher share
of anthropogenic components than in the waters of the parent river.
Maior – lake waters have a lower share of anthropogenic ions than that of the
parent river. In this case, the quality of lake waters is shaped by processes related
mainly to chemical denudation of the sediments of the reservoir’s basin.
Integralis – lakes showing an apparent similarity in the size of lake and river β
indices. Potamic supply is the main factor shaping the quality of lake waters. The
limits of the F index ranges for the distinguished lake types are the arithmetic mean
± half of the standard deviation. When the distribution of quality parameters of
the analyzed lake waters corresponds to the normal distribution, the defined limits
divide the area of the variability of the index value into three ranges, the narrowest
of which is the middle range (integralis). This is due to the need to emphasize
the hydrochemical similarity of limnic and potamic waters. The value [F] below
85% means a transformation of lake waters in the direction of pollution growth
and belonging to type 3 (minor). The opposite situation (F-value > 115%) is
represented by waters of lakes of natural hydrogeochemical character, the quality
of which is shaped by the supply from the own catchment. The values [F] in the
range of 115–85% correspond to type 2 (integralis).
The way of connection between the lake and the parent river and the forms of
supplying the lake basins constituted the basis for distinguishing three types of lakes
within each of the lake types. Interzonal lakes (IZ) are lakes with a hydrologically
dominant role of the reservoir own catchment area. When the area of lake recharge is
a catchment area of the parent river, one deals with extrazonal reservoirs (EZ). The
third group of mixozonal reservoirs (MZ) are those lakes in which there is no clear
dominance of a particular type of catchment.
J. Dawidek et al.
floodplain lakes are determined by the supplying waters of the own catchment. The
quality of lake waters is then determined by atmospheric precipitation, surface and
underground inflow (hypodermic and from a deeper groundwater table). In turn, the
flooding is an important but only cyclical episode in flood ecosystems, during which
lakes are only the recesses of submerged flood terraces [41]. General hydrochemical
relationships resulting from the cycle of successive potamophases and limnophases
and their effect on the quality of valley waters can be expressed with the β index. It
is the ratio of Ca
2+ cation concentration to the sum of Cl
− and SO 4
2− anions concentrations [42]. Calcium, as a product of calcium carbonate dissociation processes, is
treated as a geogenic ion, typical for the natural environment with a significant share
of carbonate sediments. Sulfates and chlorides, being good migrants, are an indicator
of the degree of anthropogenic transformation of the environment. The percentage
quotient of the limnic and fluvial index β
F =
β lakes
β rivers
is the basis for determining
the similarity or difference in the quality of these two environments. On this basis,
the following groups of lakes can be distinguished:
Minor – lakes with a low F-value. The waters of these lakes have a higher share
of anthropogenic components than in the waters of the parent river.
Maior – lake waters have a lower share of anthropogenic ions than that of the
parent river. In this case, the quality of lake waters is shaped by processes related
mainly to chemical denudation of the sediments of the reservoir’s basin.
Integralis – lakes showing an apparent similarity in the size of lake and river β
indices. Potamic supply is the main factor shaping the quality of lake waters. The
limits of the F index ranges for the distinguished lake types are the arithmetic mean
± half of the standard deviation. When the distribution of quality parameters of
the analyzed lake waters corresponds to the normal distribution, the defined limits
divide the area of the variability of the index value into three ranges, the narrowest
of which is the middle range (integralis). This is due to the need to emphasize
the hydrochemical similarity of limnic and potamic waters. The value [F] below
85% means a transformation of lake waters in the direction of pollution growth
and belonging to type 3 (minor). The opposite situation (F-value > 115%) is
represented by waters of lakes of natural hydrogeochemical character, the quality
of which is shaped by the supply from the own catchment. The values [F] in the
range of 115–85% correspond to type 2 (integralis).
The way of connection between the lake and the parent river and the forms of
supplying the lake basins constituted the basis for distinguishing three types of lakes
within each of the lake types. Interzonal lakes (IZ) are lakes with a hydrologically
dominant role of the reservoir own catchment area. When the area of lake recharge is
a catchment area of the parent river, one deals with extrazonal reservoirs (EZ). The
third group of mixozonal reservoirs (MZ) are those lakes in which there is no clear
dominance of a particular type of catchment.