Daniel Szymański

Spatial variability of nutrients (N, P) in a deep, temperate lake with a low trophic level supported by global navigation satellite systems, geographic information system and geostatistics

We investigated changes in the spatial distribution of phosphorus (P) and nitrogen (N) in the deep, mesotrophic Lake Hańcza. The raw data collection, supported by global navigation satellite system (GNSS) positioning, was conducted on 79 sampling points. A geostatistical method (kriging) was applied in spatial interpolation. Despite the relatively small area of the lake (3.04 km(2)), compact shape (shore development index of 2.04) and low horizontal exchange of water (retention time 11.4 years), chemical gradients in the surface waters were found. The largest variation concerns the main biogenic element - phosphorus. The average value was 0.032 at the extreme values of 0.019 to 0.265 mg L(-1) (coefficient of variation 87%). Smaller differences are related to nitrogen compounds (0.452-1.424 mg L(-1) with an average value of 0.583 mg L(-1), the coefficient of variation 20%). The parts of the lake which are fed with tributaries are the richest in phosphorus. The water quality of the oligo-mesotrophic Lake Hańcza has been deteriorating in recent years. Our results indicate that inferences about trends in the evolution of examined lake trophic status should be based on an analysis of the data, taking into account the local variation in water chemistry.

Variation of nitrogen forms in lakes with different intensity of anthropogenic pressure

Abstract The aim of this study was to compare the concentration of nitrogen and trace the dynamics of its changes in two lakes with different intensity of anthropogenic pressure. The dominant land use of Lake Paskierz catchment is built-up areas, while in Lake Sajmino, wasteland is the dominant land use. The total amount of nitrogen in Lake Paskierz ranged from 1.68 to 6.58 g Ntot m-3, while in Lake Sajmino it was from 1.03 to 1.84 g Ntot m-3. The organic fraction was a dominant form in the surface water layers of the examined lakes. A slightly different situation was found in near-bottom water layers of Lake Paskierz, where ammonium nitrogen was the dominant form in the summer stagnation. In other cases organic nitrogen was a dominant form in each of the reservoirs. Concentrations of nitrites and nitrates were low and did not affect essentially the overall amount of nitrogen in the studied lakes. Based on the results, it can be concluded that Lake Paskierz is overfertilized. The high concentrations of ammonia measured in near-bottom layers of the lake indicate that the internal supply may be a very important process affecting the trophic status. Lake Sajmino was characterized by significantly less nitrogen abundance, although the periodically increasing nitrogen concentration reveals the presence of adverse anthropopressure on the lake.

Comparison of coagulation behaviour and floc characteristics of polyaluminium chloride (PAX 18, PAX XL19H, ALCAT) with surface water treatment

Abstract Coagulation behaviour of polyaluminium chloride (PACl) was comparatively investigated in terms of the removal of turbidity and colour with surface water. The growth of flocs was also compared. The results show that the decrease in saturation and values of dissolved oxygen was ca. 20% for ALCAT and PAX 18 at both dosages and 15% for PAX XL 19H, respectively. The floc formation growth indicated that PACl coagulation occurred not only by charge neutralization but also by a form of sweep flocculation. Besides, flocs formed by ALCAT had better sizes than the flocs formed by PAX 18 and PAX XL19H. The rate of sedimentation was stable during coagulation with higher doses, and it was dependent on the substance used.

Bottom sediments as a potential source of phosphorus in the riverine-lacustrine system of the Kośna River (Northeastern Poland)

Abstract Sediments from hypereutrophic Lake Łajskie localized in northeastern Poland were examined on the basis of P-fraction. The sediments were collected at five sampling sites. In the investigated lake, the rank order of P-fractions was HCl-P > BD-P > NH4Cl-P > NaOH - nrP. The loosely sorbed phosphorus NH4Cl-P represented < 3% of the sedimentary inorganic phosphorus, while the reductant phosphorus (BD-P) ranged from 2 to 10%. The calcium bound phosphorus (HCl-P) showed considerable contribution (59-74%) to the sedimentary inorganic P-loads. BDP was the most reactive fraction in Lake Łajskie. Iron compounds and organic matter seem to play a significant role in regulating this labile P-budget.

BOTTOM DEPOSITS OF STRATIFIED, SEEPAGE, URBAN LAKE (ON EXAMPLE OF TYRSKO LAKE, POLAND) AS A FACTOR POTENTIALLY SHAPING LAKE WATER QUALITY

The object of the study was Tyrsko Lake (area 18.6 ha, max. depth 30.4 m), located in the western part of Olsztyn (Olsztyn Lakeland). This lake is one of the clear water lakes in Olsztyn, but the progressive deterioration of water quality has been observed during recent years. The phosphorus concentration in the water-sediment interface, phosphorus fractions quantity and the amount of components which can bind this element was investigated in the upper (0–5 cm) layer of deposits. The aim of study was to analyze the potential influence of bottom sediment on the lake water quality. The obtained results revealed that the bottom sediment of Tyrsko Lake can be classified as mixed, silica-organic type, with a relatively high content of iron (over 4% Fe in d.w.). The total phosphorus content was ca. 3.5 mg P g-1 d.w. on average. Phosphorus in the bottom sediment was bound mainly with organic matter (NaOH-nrP fraction), which had over 50% share in TP. Highly mobile fractions (NH4-Cl-P and BD-P) together only included ca. 5% to 7% TP. The obtained results show that the bottom sediment of Tyrsko Lake can bind phosphorus quite effectively. The calculated internal mineral phosphorus loading during summer stagnation period was 10.9 kg and it was lower that the assessed annual external phosphorus load (22.6 kg). The assessed annual phosphorus loading from both sources was still lower than the critical load according to Vollenweider criteria. However, due to the fact that the internal loading phenomenon is occurring in the lake, it should be taken into consideration that the lake water quality can deteriorate gradually during the longer time perspective. These findings should be accounted for in the future if the potential protection and restoration procedures will be developed.

Comparison of selected methods used in the assessment of contamination with heavy metals in littoral sediments of lakes

Abstract This study compared selected methods of assessing the pollution in the littoral sediments by heavy metals (Zn, Cu, Pb, Ni and Cd) in 13 lakes of the Borecka Forest. For this purpose, the ecotoxicological criteria (PEL TEL), the geoaccumulation index (Igeo), the contamination factor (CF) and the contamination degree (Cd) were applied. Characteristic values for both Poland (GBP) and the Earth’s crust (GBE) were assumed as the geochemical background. In addition, the organic (TOC) and inorganic (TIC) carbon were determined in the analyzed sediments. Regardless of the method or adopted background value, the highest pollution level was in the littoral sediments of Lake Szwałk Mały and Lake Kacze. This was primarily associated with increased concentrations of Cd (1.25 and 0.64 mg kg−1, respectively), which was considered as “likely to have toxic effects on organisms” (exceeding PEL). Several potential sources of this metal (fertilizers, herbicides, leaky septic tanks, bait fishing, drainage ditches, allochthonous organic matter) were identified. The content of heavy metals in the littoral sediments of other lakes was sufficiently low and they could be considered as basically uncontaminated.

The use of biopreparations in lake restoration − experimental research

Abstract The experiment was established in a set of containers. Every container held a 10 cm thick layer of profundal sediments and water from a badly polluted lake. The following five preparations were tested (brand names): AQUAKALGON+, BIOGEN REMEDIANT, BIODENN K, ECOTABS 1(TABLETS), ECOTABS 2(POWDER). The biological preparations were applied twice: phase I lasted 56 days and phase II was continued for 21 days. The research results demonstrated that considerably higher values, compared to the control, were initially (day 3) obtained for TOC after the application of ECOTABS 1, for total nitrogen − after BIODENN K and ECOTABS 1, and for total phosphorus − after BIODENN K, ECOTABS 1 and BIOGEN REMEDIANT. Multiplying bacteria might have been an additional source of organic matter in water, which was subsequently deposited in the bottom sediments as implicated by a higher percentage (by 1 to 7% of d.w.) of organic matter in the sediments at the termination of the experiment. Our preliminary experiment did not provide any justification for using the tested preparations in lake restoration efforts. Subsequent studies should focus on the question whether mineral phosphorus released to the lake water or a drastic change in the environmental conditions would not lead towards the dominance of invasive and highly toxic cyanobacteria.

Hourly and daily variability in nitrogen and phosphorus in a lake restored by the hypolimnetic withdrawal method

Abstract An excess of nitrogen and phosphorus causes an increase in productivity, leading to degradation of a water reservoir. In order to reduce the eutrophication, protective and restoration methods are used. The objective of the paper was to determine the hourly and daily variability in nitrogen and phosphorus compounds in a lake restored by the hypolimnetic withdrawal method. In the epilimnion, the organic form dominates: 97% of Ptot and 75% of Ntot. Hourly variations in the concentration of the investigated compounds indicate that the highest values occurred at night and in the morning, whereas lower measurements were recorded at noon and in the evening. Such a distribution of the concentrations of nutrients during a day is strongly associated with photosynthesis. Along with depth, the proportion of this form decreased in favor of mineral forms. A high content of mineral phosphorus (70%) and ammonium ions (75%) in the hypolimnion results from their release from bottom sediments under anaerobic conditions. As a result of the generated thermocline, they are blocked and accumulated. At the experimental station, the concentration of mineral compounds was at a lower level than at the reference station since their amount was systematically reduced by the outflow of over-fertilized waters from the hypolimnion.

Characteristics of bottom sediments of Lake Widryńskie

Abstract The aim of this study was to determine the chemical composition of Lake Widryńskie bottom sediments (max. depth. 27.0 m, area 123.9 ha). The sampling of bottom sediments was conducted once, on 16 August 2010. Sampling was made in 10 specific areas. Among the 10 samples, 4 samples were taken from the littoral and sublittoral zones, while the rest were taken from the profundal zone. The dominant component of the sediments was silica and calcium carbonates were subdominant. Based on the survey, it was determined that silica occurred in greater numbers in littoral sediments, while in sublittoral sediments there was increased participation in the chemical composition of organic matter. The elements that build a capacity complex were a small percentage of the dry weight of sediment. Sediment from the vicinity of inflows contains higher amounts of silica, which confirmed the impact of the catchment on the chemical composition of sediments.