Citizen scientist monitoring accurately reveals nutrient pollution dynamics in Lake Tanganyika coastal waters

Abstract

Several studies in Lake Tanganyika have effectively employed traditional methods to explore changes in water quality in open waters; however, coastal monitoring has been restricted and sporadic, relying on costly sample and analytical methods that require skilled technical staff. This study aims in validating citizen science water quality collected data (nitrate, phosphate and turbidity) with those collected and measured by professional scientists in the laboratory. A second objective of the study is to use citizen scientist data to identify the patterns of seasonal and spatial variations in nutrient conditions and forecast potential changes based on expected changes in population and climate (to 2050). The results showed that the concentrations of nitrate and phosphate measured by citizen scientists nearly matched those established by professional scientists, with overall accuracy of 91% and 74%, respectively. For total suspended solids measured by professional and turbidity measured by citizen scientists, results show that, using 14 NTU as a cut-off, citizen scientist measurements of Secchi tube depth to identify lake TSS below 7.0 mg/L showed an accuracy of 88%. In both laboratory and citizen scientist-based studies, all measured water quality variables were significantly higher during the wet season compared to the dry season. Climate factors were discovered to have a major impact on the likelihood of exceeding water quality restrictions in the next decades (2050), which could deteriorate lake conditions. Upscaling citizen science to more communities on the lake and other African Great Lakes would raise environmental awareness, inform management and mitigation activities, and aid long-term decision-making.

Citizen scientists filling knowledge gaps of phosphate pollution dynamics in rural areas

“…Seasonal PO 4 dynamics that more closely follow precipitation dynamics indicate more episodic PO 4 loads and can be caused by point as well as diffuse pollution sources (Moshi et al, 2022 ). These can include agricultural runoff, combined sewage overflows (spills) and stored phosphorus in river sediments, all of which can release more PO 4 during periods of elevated precipitation.…”

“…PO 4 is detected using 4-amino-antipyrine with phosphatase enzyme which produces a coloured solution which is compared to a standard reference colour chart, assigning colour brightness to one of seven concentration intervals. Side-by-side measurements have shown an overall accuracy of 75% to 85% of the citizen scientist estimated PO 4 concentrations compared to concentrations measured at the same site and day by professional scientists using standard laboratory analysis (Hegarty et al, 2021 ; Moshi et al, 2022 ). Sources of errors include the misreading of the colorimetric scale and differences between the time of measurement, directly in the field for citizen scientists and after transportation to the lab for professional scientists.…”

“…Comparisons between citizen scientists measuring the same sample have been performed in individual projects and shows high inter-rater agreement (Cohen’s κ > 0.70). Quality control of all data is performed by Earthwatch Europe and by local partners by identifying anomalies and inconsistencies within and between datasets (Moshi et al, 2022 ). Automated feedback is provided through the app at the moment of data acquisition to the citizen scientist, based on inconsistencies within each completed dataset.…”

Empowering citizen scientists to improve water quality: from monitoring to action

“…Citizen scientists employ various approaches and methods to monitoring (Blanco-Ramírez et al, 2023), and although concerns over accuracy, precision and reliability of citizengenerated data have been considered in several studies (Quinlivan et al, 2019;Moshi et al, 2022;Stankiewicz et al, 2023), still, there remain barriers to the use of these data. Much work has been done by scientists who have used CS as a strategy for data collection or focused on data accuracy comparisons, by non-governmental organizations or by other local or community groups which have not necessarily impacted the national and political scale for water quality reports.…”