Search

A method of the simultaneous reduction of external and internal load of phosphorus as a new solution for lake restoration is presented. A flow-through, stratified lake, with diverse morphometry was selected for the study. In all three parts of the lake, an oxygen deficit was noted at the lake bottom at peak summer stagnation, with a simultaneous increase in mineral forms of phosphorus (the concentration of orthophosphates at sites I, II and III reached 0.301, 0.318 and 0.395 mg P l−1, respectively). Additionally, a large load of nutrients originating from the main inflow (annual load of 14395.9 kg P y−1 and 16 4829.8 kg N y−1), indicates that the conditions present in the lake are conducive to more intensive eutrophication. In this situation, reduction of the main loads of nutrients can be achieved by the simultaneous employment of pipelines delivering oxygenated water to the lake bottom during summer stagnation and a pipeline withdrawing deoxygenated and nutrient-rich water from the bottom in the vicinity of the outflow from the lake. It has been calculated that during the period of summer stagnation (VI-IX), the operation of delivering pipelines can reduce the phosphorus load from the main inflow by 5800.5 kg (40.3%). Using the pipeline withdrawing (site III), the amount of phosphorus removed from the lake would increase by 30.4% (from 2259.6 kg to 3247.8 kg). An additional solution, can be dosing the precipitating substances into the pipes delivering water to the lake, which will enable precise inactivation of phosphorus.

The article presents a novel, practical, sustainable and multi-purpose conceptual method for urban lakes water treatment. It is based on the separation of the inflowing water from the lake's main body with an impermeable barrier and a construction of enhanced littoral zone. The impermeable barrier alongside the shoreline creates a new littoral zone between the land and the lake water. Inflowing water as well as nutrient-rich seepage water from a direct catchment will be pretreated in a specially constructed biotic and abiotic zones. The naturally formed community of macrophytes in the littoral zone ensures biological pretreatment. The remaining phosphorus load will be eliminated in the abiotic part of the system composed of natural, cost-efficient and easily accessible sorption material. Based on nutrients budget calculated for a few urban lakes, we estimate that the diversion of the main nutrient-rich river inflow and the cutoff of the littoral zone will reduce a load of nitrogen and phosphorus by more than 80% and 90% respectively.

The attempts to restore Lake Wolsztynskie, by direct dosing to the water iron sulphate (PIX 113) and chloride polyaluminium (PAX 18) in 2005–2006, and then iron chloride to the lake's bottom sediments in 2012–2013, resulted in only short-lasting improvement of water quality. In 2016, the physicochemical and biological parameters have shown that the lake should be classified into eutrophic and even hypertrophic, primarily because of the high concentrations of phosphorus and chlorophyll a as well as low visibility. Although in theory, the methods of restoration were selected correctly, in practice, the improvement of water quality in a flow-through lake without eliminating the influx of water from allochthonous sources of pollution was impossible. The total load of nutrients arriving in Lake Wolsztynskie from the direct catchment, that is point and atmospheric sources, was 1877 kg P and 17 137 kg N, respectively. At the moment, the actual load of phosphorus in Lake Wolsztynskie is about 12-fold higher than the one deemed as tolerable by the ecosystem. About 86% of the phosphorus load is delivered from the main river (Dojca River), thus, elimination of this source of pollution is the necessary condition for attaining lasting improvement of the water quality in this lake. Analyzing the hydrological conditions, landscape relief as well as economic and environmental conditions, a possible solution of cutting the Dojca River waters from Lake Wolsztynskie was given.

We studied an urban, flow-through lake with a large total catchment area, in the context of implementing complex protection and restoration methods in the shoreline zone and within the lake’s basin. The study was found that the annual total load of nutrients was 4 688 kg P and 50 652 kg N, which – when converted to the lake’s unit area – corresponded to 8.2 g P m −2 y −1 and 88.4 g N m −2 y −1 . Taking into account the surface inflows alone, the current actual phosphorus load of the lake is over 20-fold higher than the permissible one. An additional source of phosphorus is the lake’s bottom sediments, which is confirmed by the negative balance of this element (−2 882.5 kg P y −1 ). Despite the polymictic type of the lake, oxygen deficits may appear near its bottom, which intensify the internal enrichment process. At present, the primary production in the lake is extremely large, which is indicated by a very high oxygen content (the maximum value of 230%) coinciding with a very high pH value (around 9.7 at both sites) as well as a high chlorophyll a and seston content (158 mg m −3 and 30.6 mg dm −3 at sites S-1, 176 mg m −3 and 33.4 mg dm −3 at sites S-2, respectively), and a low visibility of Secchi disc (around 0.5 m at both sites). At such advanced trophy of the lake and high content of phosphorus (TSI(TP) = 100), it is impossible to stop the rapidly progressing degradation of this water body without man’s intervention. The only possible way to eliminate allochthonous sources of pollutants is by constructing a system of pipelines and waterproof walls for transporting pollutants outside the lake’s catchment. Selection of adequate technological solutions must be preceded by a detailed analysis of hydrological and morphometric properties of the water body, parameters of its catchment and the potential use of lake water in the context of economic calculations. An innovative approach may involve self-oxygenation of lake waters by supplying some of a lake’s surface inflow water to the lake’s bottom. This method can assist in improving oxygen conditions, which to a large extent will reduce the internal supply. It can also be a supporting method in the process of phosphorus inactivation with the use of safe ferrous coagulants, whose efficiency of phosphorus precipitation and immobilization depends on the oxygen content.

We analysed total bacterial number and mean volume of cells at three sites in each of ten floodplain lakes in the Middle Basin of the Biebrza River, North-Eastern Poland to test bacterioplankton communities change according to the distance to the river. The composition of the bacterial communities was determined by fluorescent in situ hybridization method. Total number of bacteria in the lakes ranged from 4.0 to 7.48 cells × 10 6 mL −1 with dominance by Actinobacteria, the contribution of which was positively correlated with water level. Old river channels (side-arms) featured Alpha- and Gammaproteobacteria. The community of Betaproteobacteria was limited by concentration of dissolved organic carbon. Archaea, in spite of a minor role (

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.

We investigated the effect of long-term inflow of untreated municipal sewage on the trophic status of the four urban lakes (Mielenko, Karczemne, Klasztorne Male, Klasztorne Duze) connected by the river into one system. We delineated the catchments and sub-catchments of the individual lakes, to determine their hydrological parameters as well as the physicochemical properties of water in the lakes, their surface inflow and outflow as well as water discharged to lakes from stormwater and drainage ditches. Results of the TSI demonstrated that Karczemne Lake and Klasztorne Male Lake were the most polluted of the analyzed lakes. The value of TSITP was extremely high: 103 and 85, respectively. The biggest hazard for the quality of waters in the lakes was: angling in Mielenko Lake (44.8%); point sources (42.1%) and the inflow from Mielenko Lake (33.5%) to Karczemne Lake; the inflow from Karczemne Lake (60.4%) and point sources (35.9%) for Klasztorne Male Lake; and the inflow from Klasztorne Male Lake (95.2%) to Klasztorne Duze Lake. According to Vollenweider’s hydraulic model, the actual phosphorus load introduced to Mielenko Lake is double the critical load (7.8 kg y −1 ); in Karczemne and Klasztorne Male Lakes, the critical load is exceeded by 700% (12.1 kg y −1 and 37.8 kg y −1 , respectively) and in Klasztorne Duze Lake, the actual load is 1000% higher than the critical one (the critical load—96.0 kg y −1 ). With such high phosphorus concentrations, natural inhibition of the lake’s severe degradation is impossible. To achieve permanent water quality improvement we recommend the comprehensive protective and restoration actions: constructing pipelines and perimeter drainage ditches with waterproof walls sealed with PVC vinyl sheet piling along the entire lake system; removal of the bottom sediments from Karczemne Lake and some of the bottom sediments from Klasztorne Male Lake; phosphorus inactivation in the lakes Mielenko, Karczemne and Klasztorne Male, along with supportive actions in the form of biomanipulation.

We investigated the effect of withdrawal of nutrient rich hypolimnic waters on diel changes in water column physicochemical conditions, composition of pelagic communities and metabolic processes over a 5-day period. The study was done during stratification in the eutrophic Kortowskie Lake divided into a southern experimental part with removal of near-bottom water by a pipe directly to the outlet, and a northern control part unaffected by the pipe. Volumetric metabolic rates with depth were calculated in each basin using 6 daily vertical profiles of dissolved oxygen (DO). Results demonstrated that withdrawal of near bottom water increased hypolimnic water temperature by 1.3 °C decreasing the strength of thermal stratification. This increased phytoplankton biomass and primary production in the metalimnion of the experimental part of the lake, which became dominated by Cyanobacteria, and more net autotrophic compared to the photic zone of the control site. Daily variability in gross primary production (GPP), ecosystem respiration (R), and net ecosystem production (NEP = GPP–R) of the photic zone and metalimnion indicates the highly dynamic physical (mixing and light) and biological (pools of phytoplankton and bacteria) conditions occurring in the photic layers. In the control part of the lake, a multiple regression analysis showed that vertical patterns in GPP and R depended on phytoplankton biomass and total nitrogen and NEP followed changes in particulate organic carbon. In the experimental part of the lake, vertical patterns in NEP were only significantly related to changes in temperature. But as the temperature was positively correlated with bacterial abundance, this was most likely the main driver of variation in NEP with depth (relationship between R and medium cell volume (MCV), bacterial biomass (BB), respectively: r = 0.60; r = −0.63; n = 15; p

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 km2), 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.

Total organic carbon (TOC) can be one of the parameters used to determine trophic state in lakes, as shown by the statistically significant correlation between TOC and chlorophyll, total phosphorus and Secchi disk transparency. Calculation of the TSI index based on TOC according to the formula TSI(TOC) = 20.59 + 15.71 ln(TOC) and its introduction as an additional index to the classification by Carlson may optimize the comparative analysis of lakes and allow a measurable assessment of lakes with respect to the trophic gradient.

Hypolimnetic withdrawal as a restoration method comprises the withdrawal of the nutrient-rich hypolimnion by a pipe directly to the outlet, thus replacing the surface outflow. The method was first applied to Lake Kortowskie in 1956 and continues today. The direct effects of hypolimnetic withdrawal can be observed in the near-bottom waters during the pipe's operation (May-Sep). The treatment depends on the quantity of water withdrawn by the pipe. A high withdrawal rate increased the rate of hypolimnetic heating, diminished the water mass stability and shortened summer stagnation. Hypolimnetic withdrawal did not improve the oxygen conditions in Lake Kortowskie, although it shortened the duration of the anaerobic conditions near the bottom and diminished the spatial extent of oxygen deficiency. Increased release of phosphorus from the bottom deposits to the near-bottom water and finally the outlet via the withdrawal pipe has been observed, with a consequent impoverishment of the upper sediments. The...

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.

Key-words: organic carbon, lakes, morphometry, catchment The study lakes are located in north-eastern Poland, in the same physiographic system. These lakes were formed during the last glacial period. The lakes differedin morphometry,catchment size and environmental conditions. The study included deep, clear water lakes that stratify in summer. The results from multiple linear regression equations indicate that the morphometric and catchment variables may influence mainly the particulate fraction of OC during summer stratification. No significant correlation was found between the examined parameters and the quantity (DOC) or the carbon-specific absorbance (SUVA260) of the dissolved fraction. The most important factors which determine POC abundance in lakes are the maximum depth (zmax), length and development of shoreline (L, DL), catchment area to lake volume (CA/V), and stratification percentage (“% strat.”), as well as epilimnion bottom area to epilimnion volume (AE/VE). Thus, in the summer the quantity of OC in lakes, especially of POC, will be determined by the in-lake production and consumption processes. Low productivity can be easily maintained in deep, strongly stratified lakes, and therefore should be protected and high water quality should be preserved.