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The role of humic substances in self-purification of river water ecosystems in mixing zonesтезисы доклада
- Авторы: Lasareva E.V., Parfenova A.M.
- Сборник: Book of Abstracts of the 21st International Conference of IHSS "Natural organic matter and humic substances for sustainable development" Santiago Chile, August 6-11, 2023
- Тезисы
- Год издания: 2023
- Место издания: Santiago, Chile
- Номер статьи: Po-S6-74
- Аннотация: Self-purification of river water as a set of physical, biological and chemical processes aimed atrestoring its natural properties is particularly important in the mixing zone where river water is mixed with sea water. According to V.I. Vernadsky, in such zones of significant biogeochemical activity there is a constant exchange between inert and living matter. In the mixing zones an avalanche-like precipitation of colloidal and suspended matter carried by rivers occurs before entering the marine environment.The aim of our work is to study the mechanisms of deposition of river matter using a biogeochemical approach, showing self-purification of river water as an interaction between inert and living matter. Mineral components (clays, carbonates, ferric hydroxide) and Humic Substances (HS) (leonardite, Powerhumus, Humintech, Germany) were studied as models of inert matter. Chitosan (Ch) (MW 83 kDa, 82 % deacetylated, BioProgress Ltd, Russia) was taken as a model of labile living matter in the mixing zone released by biota under salt stress. Sodium chloride simulated salinity.The aggregate stability of the system was monitored by measuring the optical density of suspensions (Agilent spectrophotometer, USA, at λ 535 nm) and the size of sol particles was estimated by dynamic light scattering technique (Zetatrac analyzer, Microtrac Inc., USA). The adsorption of HS was carried out using HS solutions (10 mg/L) for three days at room temperature.The addition of small amounts of Ch (<10 mg/L) into suspensions and colloids of minerals has been shown to decrease their aggregative stability due to flocculation of particles. At a high concentration of Ch, suspensions are stabilized due to the adsorption of Ch on minerals. Modification of minerals by HS leads to stabilization of suspensions even with increasing salinity. However, in the presence of the Ch, there is a sharp decrease in the stability of such suspensions. The result can be explained by the formation of a mixed layer of two polyelectrolytes where the Ch, having the opposite charge to mineral particles adheres more tightly to them, whereas HS, attaching to the mineral, form loops distributed in the solution which may interact with each other. So the minerals modified by HS are more effective in flocculation by labile organic matter. Considering the need to find new ecological methods of river water purification, our approach to the mechanism of self-purification of river water can have practical application.The model experiment is in good agreement with the data on the deposition of river suspension in the mixing zone observed under field conditions and confirms V.I. Vernadsky's idea of the existence of a close connection of living organisms with inert substances as a single system.
- Добавил в систему: Перминова Ирина Васильевна
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | Полный текст | Po-S6-74.pdf | 171,8 КБ | 24 декабря 2023 [iperminova] | |
| 2. | Краткий текст | 21st_IHSS_Conference_-_Book.pdf | 2,2 МБ | 24 декабря 2023 [iperminova] |