Modern approaches to monitoring the ecological condition of lake ecosystem waters

Abstract

Purpose. Presentation of the results of the implementation of new approaches to monitoring indicators of the ecological state of water in lake ecosystems using the example of the Danube lakes with the use of modern express methods of determining individual ecological parameters and satellite information of the water bodies' water bodies. Methods. Laboratory analysis of determining the concentration of chlorophyll-a according to DSTU 7.1. 4.02-90 "Water. Methodology for spectrophotometric determination of chlorophyll α", field measurements of water transparency with a standard Secchi disc, concentrations of chlorophyll-a, total suspended matter, spectral attenuation index using a portable hyperspectral radiometer WISP-3. Results. In the summer of 2023, 2 expeditions were carried out to the Danube lakes Kahul, Yalpug-Kugurlui, Kytai, Kotlabukh. It was established that the results of observations of water quality indicators (chlorophyll-a concentration, total suspended matter, spectral light attenuation index), obtained with the WISP-3 hyperspectral radiometer, are in good agreement with each other and with the data of laboratory analysis of the measurement of chlorophyll-a concentration and water transparency. The possibility of using SENTINEL 2 MSI satellite images, processed using the C2X-COMPLEX Sentinel Application Platform (SNAP 9.0.0) to obtain operational information on the spatio-temporal variability of chlorophyll-a and the total suspended matter concentration in the Danube lakes was evaluated. It was established that there is a sufficiently good correlation (determination coefficient 0.9 and higher) between the measured and determined values ​​of these indicators from satellite images. According to research in July 2023, it was established that the concentrations of chlorophyll-a in 2023 were higher than at the beginning of the 21st century (in 2001) in all lakes, which is an expected consequence of the replenishment of the lakes from large volumes of Danube water in the first half of 2023 after previous dry years. The greatest increase in concentrations occurred in Lake Kotlabukh. Conclusions. It has been established that the SENTINEL-2 MSI satellite images processed with the C2X-COMPLEX processor can be successfully used for the ecological state monitoring of the Danube lakes, in particular, the operational assessment of the spatio-temporal variability of such water quality indicators as the concentration of chlorophyll-a, total suspended matter and degree water transparency with a spatial resolution of 20-60 m per pixel. The WISP-3 radiometer can be used for operational determination of water quality indicators in the Danube lakes during the environmental monitoring organization with the involvement of satellite information, in particular for the purpose of its verification based on field observation data.

Keywords

• danube lakes
• ecological condition
• monitoring
• remote
• satellite monitoring
• calibration