Physical-Chemical Characteristic and Trophic Status of Some Small Lakes in Ciliwung Watershed, West Java Indonesia

Small lakes are important freshwater resources to support the quality of human life. However, small lakes in the watershed are becoming threatened ecosystems because of increasing land-use changes and anthropogenic activity. The study aimed to determine characteristic physical-chemical parameters and trophic status some small lake in Ciliwung Watershed to support the sustainable management of small lakes in the Ciliwung watershed in preventing eutrophication effects. The data was collected in April and June 2021. Measurement and analysis of water quality parameters were conducted by insitu and Laboratory. Some parameters were not in accordance with the Government Regulation number 22/2021 for class II water quality criteria (WQC), including TSS (>50 mg.L-1)., TP (>0.03 mg.L-1), COD (>25 mg.L-1) and DO (<3 mg.L-1), especially for Lake Sunter and Lake Cincin.There are two groups of lakes based on water quality and trophic status. Lake Telaga Warna Lake Cikaret, and Lake Cilodong were classified as eutrophic while lake Sunter and Lake Cincin were classified as hypereutrophic lake Lake Telaga Warna, Lake Cikaret, and Lake Cilodong, located at the upper and middle watershed, are eutrophic, characterized by deeper bottom and higher Secchi depth. At the lower watershed, Lake Sunter and Lake Cincin are hypereutrophic characterized by higher nutrients (TN and TP), COD, temperature, conductivity, salinity, and TDS. The downstream area was a densely populated area that contributed high pollution from upstream and middle of Ciliwung watershed.

The Multi-Scale Layering-Structure of Thermal Microscale Profiles

Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses. Hence, turbulent mixing and stratification processes remain greatly under-sampled. This paper contributes to addressing this problem by presenting a novel analysis of thermal microstructure profiles, focusing on their multi-scale stratification structure. Profiles taken in two small lakes using a Self-Contained Automated Micro-Profiler (SCAMP) were analysed. For each profile, buoyancy frequency (N), Thorpe scales (LT), and the coefficient of vertical turbulent diffusivity (KZ) were determined. To characterize the multi-scale stratification, profiles of d2T/dz2 at a spectrum of scales were calculated and the number of turning points in them counted. Plotting these counts against the scale gave pseudo-spectra, which were characterized by the index D of their power law regression lines. Scale-dependent correlations of D with N, LT and KZ were found, and suggest that this approach may be useful for providing alternative estimates of the efficiency of turbulent mixing and measures of longer-term averages of KZ than current methods provide. Testing these potential uses will require comparison of field measurements of D with time-integrated KZ values and numerical simulations.

Concentration Levels and Features of the Distribution of Trace Elements in the Sapropel Deposits of Small Lakes (South of Western Siberia)

The processes of the migration and concentration of trace elements during sedimentation in small continental lakes in various landscape zones of the south of Western Siberia have been studied. We provide a quantitative assessment of the concentration levels and changes in the regional geochemical background of Cd, Hg, Sb, Zn, and Pb in sapropel deposits over the past 200 years. It was shown that complex natural processes determined by a combination of azonal factors play a fundamental role in the formation of the geochemical and mineral compositions of the bottom sediments of small lakes in various landscape zones in the south of Western Siberia. These consist of: the formation of sedimentary material in the lake catchment depending on the relief, geology, soil, and vegetation cover, as well as anthropogenic influences; the formation of authigenic organic and mineral matter as a result of biological, biochemical, and physicochemical processes; and the deposition of a complex mixture of allochthonous and autochthonous matter at the bottom of a lake, which flows under conditions of prolonged ice formation (anaerobic conditions).

ESTIMATING EFFICIENCY OF POND ELECTRIC SEINE NETS OPERATION

The article considers the problem of low productivity of many fish farms, especially non-drainage ponds against the background of a growing increase in the volume of fish farming, which is typical for pond fish farming in Russia. It has been found that one of the main factors of low productivity (1–5 c/ha) is the imperfection of existing tools and methods of fishing. With significant costs of manual labor and time, the catch of farmed fish is no more than 50%. The remaining fish die mostly during winter fish kills. To reduce the proportion of manual labor and improve the efficiency of fishing in non-drainage ponds, many countries are looking for the methods to modernize existing or develop new fishing gear. The most promising in this respect are electric breeders for fishing in the non-drainage ponds, small lakes and water reservoirs. The advantages of this method are the coverage of a large fishing zone, the possibility of catching fish leaving ordi-nary seines, and work in silted and tied water bodies. Studying the regularities of the electric field impact on fish is necessary to explain and predict its behavior in electric fields, to develop technical means that provide the necessary control activity, to develop measures to protect ichthyofauna from the harmful effects of electric fields, etc.

Warm Arctic Proglacial Lakes in the ASTER Surface Temperature Product

Despite an increase in heatwaves and rising air temperatures in the Arctic, little research has been conducted into the temperatures of proglacial lakes in the region. An assumption persists that they are cold and uniformly feature a temperature of 1 °C. This is important to test, given the rising air temperatures in the region (reported in this study) and potential to increase water temperatures, thus increasing subaqueous melting and the retreat of glacier termini from where they are in contact with lakes. Through analysis of ASTER surface temperature product data, we report warm (>4 °C) proglacial lake surface water temperatures (LSWT) for both ice-contact and non-ice-contact lakes, as well as substantial spatial heterogeneity. We present in situ validation data (from problematic maritime areas) and a workflow that facilitates the extraction of robust LSWT data from the high-resolution (90 m) ASTER surface temperature product (AST08). This enables spatial patterns to be analysed in conjunction with surrounding thermal influences, such as parent glaciers and topographies. This workflow can be utilised for the analysis of the LSWT data of other small lakes and crucially allows high spatial resolution study of how they have responded to changes in climate. Further study of the LSWT is essential in the Arctic given the amplification of climate change across the region.

Specific Features of the Macrozoobenthic Communities of Small Arctic Lakes in Eurasia

The taxonomic structure, typology, species richness, and total abundance of bentic and littoral macroinvertebrate communities from small lakes of the Arctic and Subarctic zones are considered on the basis of original data from three northern Palearctic regions (the foot of the Putorana Plateau, Kolguev Island, and Western Svalbard Island). A comparative analysis of the communities of these regions has been carried out. The features of High Arctic insular, Low Arctic, subarctic, and boreal lake communities are discussed using a large volume of literature data. The complex pattern of changes in the total benthos biomass of small lakes has been revealed: it decreases in the subarctic taiga, increases in the hypoarctic tundra, and decreases again in the High Arctic.

Viscosity and Natural Evaporation Studies: Aqueous Solutions of Surfactants and Hydrotopes

Surfactants are known to affect evaporation performance of solutions. They are studied in relation to water loss prevention. In previous studies, evaporation suppressants have been effective in the laboratory and at small scales such as on swimming pools, ponds, and small lakes. Surfactants could be useful under drought conditions in arid areas of the world. Previous researchers conducted tests to estimate the spreading and coverage efficiencies of evaporation suppressants. Effectiveness of the suppressants in reducing evaporation is evaluated. Monolayers are one molecule thick films that form at a phase boundary such as the air-water interface. The optimal methods of spreading and reapplication of monolayers need to be determined. Hydrotopes are organic salt compounds and they improve the ability of water to dissolve other molecules. Hydrotropy is one of the solubility enhancement techniques which enhance solubility with use of hydrotropes. The purpose of the research is to measure the viscosity and natural evaporation of selected aqueous surfactant and hydrotope solutions. The viscosity of the aqueous-surfactant solutions at various concentrations are measured with falling-ball viscometer. The surfactants are shown to increase viscosity when added to distilled water. Some surfactants and hyrotopes reduced natural convection water loss over five days showing an effect on evaporation rates.