15 Monitoring of Small Catchments in …
365
were noted in the winter, whereas in the growing season they tended to fall and reach
a minimum in August (Fig. 15.13).
The agricultural nature of the experimental catchment of the Struga Toru´ nska was
reflected in a rising content of biogenic substances (Fig. 15.12). In the stretch of the
river between Lipowiec and Koniczynka, increased concentrations of the following
compounds were observed every year: nitrate nitrogen (mean increase from 1.3 to
4.8 mg N-NO 3
. dm
−3 ), phosphate phosphorus (from 51 to 74 µg P-PO 4
. dm
−3 ) and
total phosphorus (from 148 to 188 µg P
. dm
−3 ).
Throughout 2017 high concentrations of nitrate nitrogen were observed, reaching
28.9 mg N-NO 3 .dm
−3 at the Koniczynka site in the winter (Fig. 15.13). As mentioned,
the reason for the increase of a number of mineral parameters is not known and may
be connected with the nature of certain agricultural practices in the fields within the
catchment carried out at the time.
A high concentration of nitrate nitrogen in winter and early spring months is a
characteristic of the quality of water subject to strong agricultural pressure. Mean
monthly values in the multi-year period show maximum nitrogen concentrations in
February–April at both sites (Fig. 15.13). In the growing season, they decreased
and reached a minimum in the summer. A comparative analysis of nitrate nitrogen
concentrations between the observation sites indicated that the parameter increased
more in the runoff from the experimental catchment in the winter than in the summer.
The phosphate index, which is regularly monitored at both sites, verifies the agricultural influence of the experimental catchment, as shown in an increase in phosphate concentration along the course of the river (Fig. 15.12). A major increase was
observed in the summer. The concentration declined at the beginning of the growing
season when the biogenic compound is in maximum demand. The highest phosphate
values were found between July and September, when the demand for the most easily
absorbed form of nitrogen (nitrate nitrogen) was increasing (Fig. 15.13).
Analysing the load of substances outflow from the experimental catchment in
the years 2004–2017, an evident annual cyclicality of nitrate nitrogen was found
(Fig. 15.12). An accelerated nitrogen runoff was observed at the end of winter and
the beginning of spring when nitrogen concentrations and flows were the highest in
a year. The smallest loads of nitrate nitrogen were observed in the summer.
Phosphate loads did not demonstrate the same regularity as nitrogen. The highest
quantities of phosphate occurred in September and January (Fig. 15.13). The lowest
loads were observed in the autumn (October–November), and their concentrations
reached a minimum in April and May.
Regarding current standards of water quality prescribed in the Regulation of
the Minister of Environment on 5.08.2016 (Dz.U. 2016.1187) “on the classification of the status of surface water bodies and environmental quality standards for
priority substances”, the mean annual values for the water in the Struga Toru´ nska in
1993–2017 were found to have exceeded the good status (class II) due to excessive
concentrations of chlorides, calcium, manganese and BOD5 at the Lipowiec site,
and nitrate nitrogen at Koniczynka. The other parameters, including those related to
heavy metals, met the requirements for a very good and good status (classes I and
II).
365
were noted in the winter, whereas in the growing season they tended to fall and reach
a minimum in August (Fig. 15.13).
The agricultural nature of the experimental catchment of the Struga Toru´ nska was
reflected in a rising content of biogenic substances (Fig. 15.12). In the stretch of the
river between Lipowiec and Koniczynka, increased concentrations of the following
compounds were observed every year: nitrate nitrogen (mean increase from 1.3 to
4.8 mg N-NO 3
. dm
−3 ), phosphate phosphorus (from 51 to 74 µg P-PO 4
. dm
−3 ) and
total phosphorus (from 148 to 188 µg P
. dm
−3 ).
Throughout 2017 high concentrations of nitrate nitrogen were observed, reaching
28.9 mg N-NO 3 .dm
−3 at the Koniczynka site in the winter (Fig. 15.13). As mentioned,
the reason for the increase of a number of mineral parameters is not known and may
be connected with the nature of certain agricultural practices in the fields within the
catchment carried out at the time.
A high concentration of nitrate nitrogen in winter and early spring months is a
characteristic of the quality of water subject to strong agricultural pressure. Mean
monthly values in the multi-year period show maximum nitrogen concentrations in
February–April at both sites (Fig. 15.13). In the growing season, they decreased
and reached a minimum in the summer. A comparative analysis of nitrate nitrogen
concentrations between the observation sites indicated that the parameter increased
more in the runoff from the experimental catchment in the winter than in the summer.
The phosphate index, which is regularly monitored at both sites, verifies the agricultural influence of the experimental catchment, as shown in an increase in phosphate concentration along the course of the river (Fig. 15.12). A major increase was
observed in the summer. The concentration declined at the beginning of the growing
season when the biogenic compound is in maximum demand. The highest phosphate
values were found between July and September, when the demand for the most easily
absorbed form of nitrogen (nitrate nitrogen) was increasing (Fig. 15.13).
Analysing the load of substances outflow from the experimental catchment in
the years 2004–2017, an evident annual cyclicality of nitrate nitrogen was found
(Fig. 15.12). An accelerated nitrogen runoff was observed at the end of winter and
the beginning of spring when nitrogen concentrations and flows were the highest in
a year. The smallest loads of nitrate nitrogen were observed in the summer.
Phosphate loads did not demonstrate the same regularity as nitrogen. The highest
quantities of phosphate occurred in September and January (Fig. 15.13). The lowest
loads were observed in the autumn (October–November), and their concentrations
reached a minimum in April and May.
Regarding current standards of water quality prescribed in the Regulation of
the Minister of Environment on 5.08.2016 (Dz.U. 2016.1187) “on the classification of the status of surface water bodies and environmental quality standards for
priority substances”, the mean annual values for the water in the Struga Toru´ nska in
1993–2017 were found to have exceeded the good status (class II) due to excessive
concentrations of chlorides, calcium, manganese and BOD5 at the Lipowiec site,
and nitrate nitrogen at Koniczynka. The other parameters, including those related to
heavy metals, met the requirements for a very good and good status (classes I and
II).