9 Assessment of Pollution of Water Resources and Process of Pollution Spreading
197
quality but also the features that condition the lake’s susceptibility to external influences [2]. The lakes with favorable natural conditions, more resistant to degradation,
have greater possibilities of use [31, 32].
Before taking action to protect lakes, it is advisable to learn about the pace and
direction of changes in the trophies of each of the reservoirs. Such a procedure makes
it possible to take appropriate protective measures, as well as possible withdrawal of
the effects of excessive eutrophication [31, 58, 59]. Long-term research is needed to
determine whether changes in water quality in the lake are the result of temporary
changes in environmental conditions, the result of local conditions associated with the
catchment or perhaps reflect the general deterioration of the environment associated
with increased anthropopressure [58].
Water dynamics, natural catchment conditions, and susceptibility to degradation
determine the quality of water in lakes and their trophic level [2, 4].
A recognized indicator of the trophy of lakes is aerobic conditions. They are
shaped by the mutual ratio of intensity of assimilation and dissimilation, with some
effect of oxygen exchange with the atmosphere [4, 30, 57]. There is a diversification
of the water depth of the reservoir into layers: trophogenic, in which predominance
prevails, and trophologic, in which dissimilation takes place more intensively. The
ratio of the thickness of the two layers depends on the state of the trophy of the lake;
less fertile has a more extensive trophogenic layer [29]. Oxygen systems defining
the nature, extent, and intensity of basic processes that form biocenosis, mainly in
hypolimnion, vary depending on: the seasons (geographical location), the extent of
vertical mixing of water and the impact of tank morphology on them [4].
Lange and Ma´ slanka [60] believe that the analysis of oxygen systems during the
summer stagnation period is more useful to assess the level of trophic lakes than
the multivariate analysis used in their monitoring. The conclusions regarding the
susceptibility of the reservoir to degradation arising from the analysis of aerobic
conditions relate to the actual course of the eutrophication process and not to the
potential conditions. The susceptibility of the lake to degradation determined based
on the physiographic indicators of the catchment may not have a direct relation to
the quality of the waters. The most degraded lakes do not have to be characterized by
a particularly low resistance, because their condition results primarily from strong
anthropopressure (from intensive agriculture, point sources of pollution).
An alternative to the analysis of the level of trophic water based on one parameter
is multi-indicator analysis. Methods proposed by Carlson [61] and Vollenweider
[6] are widely used, and in the country—by Kajak [12] and Zdanowski [13]. The
first one is based on measurements of concentrations in the surface waters of total
phosphorus and chlorophyll “a” in summer and the visibility of the Secchi disc.
The results of these studies, transformed using the proposed equations in numerical
values, are indicators of the state of the TSI trophism (trophic state indicators). The
second method, adopted by the OECD (Organization for Economic Cooperation
and Development), is based on the average annual and maximum concentrations
of total phosphorus and chlorophyll “a” in surface water, Secchi disc visibility and
oxygenation of the waters in summer. The basis for the classification of trophies of
lakes, proposed by Kajak [12] and Zdanowski [13] are basic indicators, ie summer
197
quality but also the features that condition the lake’s susceptibility to external influences [2]. The lakes with favorable natural conditions, more resistant to degradation,
have greater possibilities of use [31, 32].
Before taking action to protect lakes, it is advisable to learn about the pace and
direction of changes in the trophies of each of the reservoirs. Such a procedure makes
it possible to take appropriate protective measures, as well as possible withdrawal of
the effects of excessive eutrophication [31, 58, 59]. Long-term research is needed to
determine whether changes in water quality in the lake are the result of temporary
changes in environmental conditions, the result of local conditions associated with the
catchment or perhaps reflect the general deterioration of the environment associated
with increased anthropopressure [58].
Water dynamics, natural catchment conditions, and susceptibility to degradation
determine the quality of water in lakes and their trophic level [2, 4].
A recognized indicator of the trophy of lakes is aerobic conditions. They are
shaped by the mutual ratio of intensity of assimilation and dissimilation, with some
effect of oxygen exchange with the atmosphere [4, 30, 57]. There is a diversification
of the water depth of the reservoir into layers: trophogenic, in which predominance
prevails, and trophologic, in which dissimilation takes place more intensively. The
ratio of the thickness of the two layers depends on the state of the trophy of the lake;
less fertile has a more extensive trophogenic layer [29]. Oxygen systems defining
the nature, extent, and intensity of basic processes that form biocenosis, mainly in
hypolimnion, vary depending on: the seasons (geographical location), the extent of
vertical mixing of water and the impact of tank morphology on them [4].
Lange and Ma´ slanka [60] believe that the analysis of oxygen systems during the
summer stagnation period is more useful to assess the level of trophic lakes than
the multivariate analysis used in their monitoring. The conclusions regarding the
susceptibility of the reservoir to degradation arising from the analysis of aerobic
conditions relate to the actual course of the eutrophication process and not to the
potential conditions. The susceptibility of the lake to degradation determined based
on the physiographic indicators of the catchment may not have a direct relation to
the quality of the waters. The most degraded lakes do not have to be characterized by
a particularly low resistance, because their condition results primarily from strong
anthropopressure (from intensive agriculture, point sources of pollution).
An alternative to the analysis of the level of trophic water based on one parameter
is multi-indicator analysis. Methods proposed by Carlson [61] and Vollenweider
[6] are widely used, and in the country—by Kajak [12] and Zdanowski [13]. The
first one is based on measurements of concentrations in the surface waters of total
phosphorus and chlorophyll “a” in summer and the visibility of the Secchi disc.
The results of these studies, transformed using the proposed equations in numerical
values, are indicators of the state of the TSI trophism (trophic state indicators). The
second method, adopted by the OECD (Organization for Economic Cooperation
and Development), is based on the average annual and maximum concentrations
of total phosphorus and chlorophyll “a” in surface water, Secchi disc visibility and
oxygenation of the waters in summer. The basis for the classification of trophies of
lakes, proposed by Kajak [12] and Zdanowski [13] are basic indicators, ie summer