Comprehensive water quality assessment of surface sources in the city of Latacunga and the canton Pedro Vicente Maldonado in Ecuador

A study of the quality of drinking water sources - surface waters of the river systems of the city of Latacunga and the canton of Pedro Vicente Maldonado, Ecuador, was carried out during 2018 and 2019. The general sanitary water quality index (WQI) was calculated according to Russian methods, the water quality index of the National Sanitation Foundation (NSF-WQI) of the Ecuadorian water quality regulation. Results from parameterizing the water quality, obtained by WQI and NSF-WQI methods and combined into an overall scheme, were used to generate the rating scale for assessing the hydro-ecological status of aquatic ecosystems. When carrying out a qualitative and quantitative analysis of water from river reservoirs, the excess of the threshold limit values of such indicators as the biological oxygen demand and iron was determined. The calculations show that the WQI method and the NSF-WQI method lead to similar results when assessing the water quality of both reservoir of the city of Latacunga and canton of Pedro Vicente Maldonado. According to the WQI method, the hydrological state of the reservoir of the city of Latacunga was characterized in the range of a scale from “Crisis” to “Risk”, while according to the NSF-WQI method the state was assessed as “Risk”. The hydrological state of the reservoir of the canton of Pedro Vicente Maldonado, was assessed as “Risk” by both the WQI method and the NSF-WQI method. Furthermore, in none of the water bodies under study is the environmental “catastrophe” not recorded

Ecological features of the persistence of Vibrio cholerae: retrospective analysis and actual state of the problem

The review presents retrospective data on six cholera pandemics and current views on the causative agent of the seventh pandemic V. cholerae El Tor, which caused a pandemic infection with the formation of true persistent and temporary intermediate endemic foci that provide the longest pathogen circulation in the history of the disease. One of the possible explanations for such a long course of the cholera pandemic is associated with an extremely high variability of the genome and the development of a number of adaptive reactions that allow cholera vibrios to adapt and remain in the environment. Due to the development of molecular genetic research methods, the ability of cholera vibrios to form biofilms which increases stress resistance, the ability to spread by attachment to abiotic (plastic) and biotic substrates (zooplankton and phytoplankton) has been discovered. Biofilm formation is also directly related to overcoming the antagonistic action of members of aquatic ecosystems. Another strategy for the survival of cholera vibrios is the transition to an uncultured state that proves a low level of death in the population. Published data on the possible effects of temperature increasing due to the climate change on cholera outbreaks in Africa (Democratic Republic of the Congo, Nigeria, Angola, Zimbabwe, Sierra Leone), Southeast Asia (Thailand, Malaysia), Central Asia (Pakistan, Afghanistan, Kazakhstan) and South Asia (Nepal) are overviewed. Based on the publications of recent years, an analysis is made of the current state of the studied problem in the Russian Federation and, in particular, in the Rostov region

Комплексная оценка качества воды поверхностных водоисточников города Латакунга и кантона Педро Висенте Мальдонадо в Республике Эквадор

A study of the quality of drinking water sources - surface waters of the river systems of the city of Latacunga and the canton of Pedro Vicente Maldonado, Ecuador, was carried out during 2018 and 2019. The general sanitary water quality index (WQI) was calculated according to Russian methods, the water quality index of the National Sanitation Foundation (NSF-WQI) of the Ecuadorian water quality regulation. Results from parameterizing the water quality, obtained by WQI and NSF-WQI methods and combined into an overall scheme, were used to generate the rating scale for assessing the hydro-ecological status of aquatic ecosystems. When carrying out a qualitative and quantitative analysis of water from river reservoirs, the excess of the threshold limit values of such indicators as the biological oxygen demand and iron was determined. The calculations show that the WQI method and the NSF-WQI method lead to similar results when assessing the water quality of both reservoir of the city of Latacunga and canton of Pedro Vicente Maldonado. According to the WQI method, the hydrological state of the reservoir of the city of Latacunga was characterized in the range of a scale from “Crisis” to “Risk”, while according to the NSF-WQI method the state was assessed as “Risk”. The hydrological state of the reservoir of the canton of Pedro Vicente Maldonado, was assessed as “Risk” by both the WQI method and the NSF-WQI method. Furthermore, in none of the water bodies under study is the environmental “catastrophe” not recorded.Проведено исследование качества источников питьевой воды - поверхностных вод речных систем города Латакунга и кантона Педро Висенте Мальдонадо в Республике Эквадор в 2018-2019 гг. Рассчитаны общесанитарный индекс качества воды (ИКВ) по российским методикам, индекс качества воды Национального фонда охраны здоровья (NSF-WQI) эквадорского регулирования качества воды. Результаты параметризации качества воды, полученные методами ИКВ, NSF-WQI и объединенные в общую схему, позволили составить с их помощью шкалу оценки гидроэкологического состояния водных экосистем. При проведении качественного и количественного анализа воды из речных водохранилищ определены превышения нормативных значений по таким показателям, как биологическое потребление кислорода и железо. Приведенные расчеты показывают, что методы ИКВ и NSF-WQI приводят к аналогичным результатам при оценке качества воды как водохранилища города Латакунга, так и водохранилища кантона Педро Висенте Мальдонадо. Согласно методу ИКВ, состояние воды водохранилища города Латакунга характеризовалось в диапазоне шкалы от «Кризис» до «Риск», в то время как по методу NSF-WQI состояние оценивалось как «Риск». Состояние водной экосистемы водохранилища кантона Педро Висенте Мальдонадо оценивалось как «Риск» и по методу ИКВ, и по методу NSF-WQI. При этом экологическая катастрофа не фиксируется ни в одном из рассматриваемых водных объектов

Genotoxicity of Natural Water during the Mass Development of Cyanobacteria Evaluated by the Allium Test Method: A Model Experiment with Microcosms

Cyanobacteria, which develop abundantly in aquatic ecosystems, can be harmful to humans and animals not only by releasing toxins that cause poisoning but also by provoking cytogenetic effects. The influence of the mass development of cyanobacteria on the genotoxic properties of natural water has been studied in model ecosystems (microcosms) with different compositions of biotic components (zooplankton, amphipods and fish). The validated plant test system “Allium test” was used in this study. Genotoxic effects were detected at microcystin concentrations below those established by the World Health Organization (WHO) for drinking water. In all experimental treatments, cells with disorders such as polyploidy and mitotic abnormalities associated with damage to the mitotic spindle, including c-mitosis, as well as lagging chromosomes were found. Genotoxic effects were associated with the abundance of cyanobacteria, which, in turn, depended on the composition of aquatic organisms in the experimental ecosystem. Fish, to a greater extent than other aquatic animals, maintain an abundance of cyanobacteria. After one month, in microcosms with fish, mitotic abnormalities and polyploidy continued to be detected, whereas in other treatments, there were no statistically significant genotoxic effects. In microcosms with amphipods, the number and biomass of cyanobacteria decreased to the greatest extent, and only one parameter of genotoxic activity (frequency of polyploidy) significantly differed from the control