Using the geodetic and hydroacoustic measurements toinvestigate the bathymetric and morphometric parameters ofLake Hancza (Poland)

Most of the inland lakes do not have up-to-datebathymetry. However, a significant progress in surveyingtechnologies creates a possibility to quickly and accuratelydescribe the underwater environment. Modern geodeticand global positioning techniques integrated with hydroacousticsystems provide a great opportunity to study thebottom shape with high resolution. Our study presentsa reliable methodology for investigation of bathymetryand morphometric parameters with the use of GNSS positioningtechniques and single beam echosounder. Theresearch was implemented on the deepest, glacial reservoirin the central part of European Depression - LakeHancza. Direct hydroacoustic and geodetic measurementscompleted by sediment study were conducted by the authorsin 2010-2013. After performing a field survey the DigitalElevation Model was constructed and the new bathymetricmap and morphometric card were elaborated. Themaximum depth was confirmed to be 105.55 m. The finalconclusions show that the available bathymetric data andmorphometric parameters of lakes are highly dependenton the research methodology used, the precision and accuracyof measurement techniques, proper water level determination,digital elevation model and bathymetric mapelaboration processes

Materials Selection and Tests for Precise Execution of Foundry Molds Designed to Geopolymer Casts

The paper presents the results of research on the selection of material for molds intended for geopolymer castings as well as an appropriate technological process for the preparation of such castings. Three silicons with different elasticity and hardness of 30, 40 and 60Sh were tested. The above-mentioned rubbers were used to make one-piece open molds and test the performance of each material. A model having several details and a small flat surface was chosen for the replica. Based on this variation in the wall structure, it was possible to assess the accuracy of mapping, both small elements and straight cast planes. In the prepared forms 10 tests of geopolymer casting were carried out to develop the best technological process. The appropriate result was achieved when the molds covered with the divider were flooded with raw material by vibrating them on a vibrating table, and then allowed to react for an hour for free mass components and leaking gases to the surface. After a set time, the compaction was carried out again to more accurately eliminate the resulting air bubbles. The effect of this method is to obtain a cast with precisely mapped details and a smooth even surface, and almost complete elimination of air bubbles from representative surfaces

Materials Selection and Tests for Precise Execution of Foundry Molds Designed to Geopolymer Casts

The paper presents the results of research on the selection of material for molds intended for geopolymer castings as well as an appropriate technological process for the preparation of such castings. Three silicons with different elasticity and hardness of 30, 40 and 60Sh were tested. The above-mentioned rubbers were used to make one-piece open molds and test the performance of each material. A model having several details and a small flat surface was chosen for the replica. Based on this variation in the wall structure, it was possible to assess the accuracy of mapping, both small elements and straight cast planes. In the prepared forms 10 tests of geopolymer casting were carried out to develop the best technological process. The appropriate result was achieved when the molds covered with the divider were flooded with raw material by vibrating them on a vibrating table, and then allowed to react for an hour for free mass components and leaking gases to the surface. After a set time, the compaction was carried out again to more accurately eliminate the resulting air bubbles. The effect of this method is to obtain a cast with precisely mapped details and a smooth even surface, and almost complete elimination of air bubbles from representative surfaces

Long Term Sediment Modification Effects after Applications of P Inactivation Method in Meromictic Lake (Starodworskie Lake, Olsztyn Lakeland, Poland)

Lake restoration is a part of geoengineering, which is a useful tool for landscape management. The phosphorus inactivation method is one of the most popular lake restoration methods. Using chemical compounds for P binding is leading to the creation of sediment “active layer”, which should show higher P adsorption abilities, compared to non-modified sediment. Howewer, it provides rather little information, how long the modified sediment remains active, and whether it is effective in continuous P binding. Lake meromixis is not commonly observed phenomenon, and sediment located in monimolimnion area is subjected long term anoxia. Therefore, observation of “active layer” in a meromictic lake can give very important data about durability of restoration effects. The object of our study was meromictic Starodworskie Lake (5.57 ha, max. depth 24.5 m), located in Olsztyn Lakeland, Poland. In the past the analyzed lake was subjected to various restoration methods, and phosphorus inactivation method by alum use (1994–1995) was the last used treatment type. The mixing regime of this lake had changed from bradimictic (before and during restoration time) into durable meromictic (post-restoration period). The research made two decades after implementing of P inactivation showed the presence of “active” sediment layer 10–15 cm below sediment surface. This sediment layer showed much higher content of P bound to aluminum, compared to surficial sediment layer. P binding molar ratio was assessed and amounted to 16.1 straightly after restoration and 6.1 after 21 years. This fraction amounts were higher that the values noted before restoration (ca. 358% higher than in 1994) and during restoration (ca. 86% higher than in 1995), which was probably the effect of continuous phosphorus adsorption by “active layer” in post-restoration period

The use of expanded clay aggregate for the pretreatment of surface waters on the example of a tributary of Lake Klasztorne Górne in Strzelce Krajeńskie

The paper presents a proposal for the treatment of river water based on expanded clay (ceramsite). It is a lightweight mineral aggregate containing components relative to phosphorus adsorption (calcium, iron, manganese, aluminum). A pilot plant on a fractional technical scale was built on a nutrient rich (phosphorus up to 0.4 mg dm−3, nitrogen up to 10.0 mg dm−3), small (mean annual flow about 0.04 m3 s−1), natural watercourse (Młynówka River, a tributary of the Otok Channel, Noteć basin, the municipality of Strzelce Krajeńskie). The monitoring included quantitative and qualitative measurements of the water stream in 2014-2015. On the basis of the examinations, the calculated effectiveness of ceramsite filters in removing major contaminants from water was: for total nitrogen 5-6%, phosphorus 12-16%, and for suspensions 17-29%. The effectiveness of the treatment is highly influenced by hydraulic load, so this type application on a full-scale should occupy a sufficiently large volume. Taking into account simplicity of performance, ease of operation and low cost of construction and maintenance, such pretreatment plants based on expanded clay would seem to be a promising tool for the protection of surface waters in catchments of small rivers and streams

Phosphorus Removal with Coagulation Processes in Five Low Buffered Lakes—A Case Study of Mesocosm Research

This research deals with the impact of aluminum coagulants, used as a tool for the rehabilitation of water bodies, on changes in the phosphorus content in lakes with low alkalinity of water. Mesocosm scale experimental investigations in situ using polyaluminium chloride were carried out, based on five lakes with different levels of water buffering capacity (<1.0–2.5 meq L−1). The research was accomplished using three coagulant doses (half a dose, a whole dose, and a double dose calculated for phosphorus inactivation in a lake ecosystem). The results were compared with the ones from the control mesocosms. The study was carried out in two consecutive years. It was shown that the effectiveness of phosphorus removal from a water column was related to the dose of the coagulant, pH value, and the content of organic compounds. The lowest treatment effectiveness was found for lakes, with the most severe symptoms for dystrophy, which were abundant with humic compounds. As the water alkalinity increased, so did the ability of the coagulant to adsorb phosphorus, while the ecosystem’s load of aluminum in toxic forms decreased. Doubling the standard dose did not result in a noticeable improvement in the water quality. The results allow us to evaluate the chances of successful lake restoration by applying aluminum coagulants to natural water bodies which are susceptible to acidification

Sorption Properties of the Bottom Sediment of a Lake Restored by Phosphorus Inactivation Method 15 Years after the Termination of Lake Restoration Procedures

Artificial mixing and phosphorus inactivation methods using aluminum compounds are among the most popular lake restoration methods. Długie Lake (Olsztyńskie Lakeland, Poland) was restored using these two methods. Primarily, P precipitation and inactivation methods significantly increased the sorption properties of Długie Lake bottom sediment. Fifteen years after the termination of the restoration procedure, the alum-modified “active” sediment layer still has higher P adsorption abilities, which can limit P internal loading. Relatively low amounts of phosphates in the near-bottom water of Długie Lake, even in anoxia, as well as the fact that the assessed maximum sediment P sorption capacity is still higher than NH4Cl–P (labile P) and BD–P (Fe-bound P) sum (“native exchangeable P”), confirm that hypothesis. Among the tested P adsorption models for the sediment, the double Langmuir model showed the best fit to the experimental data (the highest R2 values). This may indicate that phosphorus adsorption by the tested sediments most likely occurs through phosphate binding at two types of active sorption sites. P adsorption by the studied lake sediment during experiments was significantly connected to aluminum content in sediment. The research into the adsorption properties of sediment can be used as a tool for the evaluation of lake restoration effects

A Unique Application Methodology for the Use of Phosphorus Inactivation Agents and Its Effect on Phosphorus Speciation in Lakes with Contrasting Mixing Regimes

The efficiencies of the restoration of two lakes of varied morphometries and trophic states—meromictic, hypertrophic Lake Klasztorne Małe, and dimictic, eutrophic Lake Klasztorne Duże—with the use of the phosphorus inactivation method with sequential application of iron and aluminum compounds have been compared. The total dose of the agents applied for Lake Klasztorne Małe was 38 tons of PAX 18 (aluminum polychloride) and 14 tons of PIX 111 (iron chloride), and for Lake Klasztorne Duże, it was 74 tons of PAX 18 and 46 tons of PIX 111. After the application of the compounds, better efficiency of phosphate removal from the surface water layers was obtained in the case of the dimictic, eutrophic Lake Klasztorne Duże. The use of two doses of compounds did not lead to complete precipitation of phosphates from the bottom water layers of either lake. It is noteworthy that in the case of both lakes, inhibition of the internal loading process was observed. The obtained results for the Klasztorne lakes showed that the use of two types of compounds makes it possible to reduce the cost of restoration, and moreover, the dosing of iron salts in the coastal areas of the lakes ensures a higher level of ecological safety

The Impact of the Watershed Use Changes on the Water Chemistry of the Shallow, Urban Lake—A Case Study of Lake Mielenko (Pomeranian Lakeland, Poland)

The research was carried out on the flow-through Lake Mielenko (7.8 ha; 1.9 m), which also acts as a stormwater receiver. In 2015, a disposal for road salts was created in the lake’s catchment area. As a result of the inflow of salt-contaminated stormwater, there was a significant increase in the concentration of calcium (57 mg Ca/L), chloride (220 mg Cl/L) and electrolytic conductivity (790 µS/cm). Increased calcium concentrations in lake waters changed their hardness from low to medium-hard. The ecological effect of the change in hydrochemical conditions in Lake Mielenko is the Potamogeton crispus that grows abundantly in this reservoir, which prefer calcium-rich water. The overall aesthetics of the lake have deteriorated significantly, and the availability of water for recreation has also been limited