To better understand local water quality pollution by organic contaminants and how it affects communities around the world, “The Gems of Water” project aims to build a co-creative global scientist-citizen approach, actively engaging citizens and connecting them to scientists and to advanced water monitoring tools. The project applies the Stir Bar Sorptive Extraction technique with an advanced wide-screening method, used to assess the occurrence of agrochemicals, industrial compounds and pharmaceuticals in surface and groundwaters. In collaboration between Coral Conservation and the Joint Research Centre (JRC) of the European Commission, a study was conducted to identify contamination patterns which could be affecting the coral reef by investigating water quality in local rivers in the south Caribbean region of Costa Rica, an area characterized by agricultural activities linked to bananas production. Coral Conservation is a youth-led non-governmental organization focused on activities for the conservation and protection of the coral reef. Sampling locations for the study were jointly determined with members of the Coral Conservation group and included 13 sampling points from 3 different rivers and 2 wells. The pilot study allowed evaluation of the workflow for scientist-citizen collection of water quality data, whereby participants from the local community conduct sampling and extraction activities, while the wide-screening analysis of about 230 contaminants is performed at the JRC Water Laboratory. Considering the lessons learned through the Costa Rican pilot case, in this paper we discuss the elements required for successful scientist-citizen projects. Challenges are described and outlooks provided to improve citizens’ engagement projects and others participatory water quality monitoring activities. “The Gems of Water” project contributes to data collection of rarely monitored compounds in rural and remote areas through a scientist-citizen approach, addressing knowledge gaps on water quality and building bridges between science and society. The outlook is for such an innovative approach to support bottom-up management actions which can lead to alternative solutions in water quality management.

"The Gems of Water" citizens' engagement activity united the Joint Research Centre (JRC) of the European Commission with the Costa Rican based NGO Coral Conservation to screen for pesticides in local rivers using wide-screening technology. Citizens used stir bar sorptive extraction to collect and extract samples from three rivers and two wells in the south Caribbean region of Costa Rica, an area known for export-based banana agriculture. The advanced wide-screening method provided by the JRC Water Laboratory enabled the assessment of 230 agrochemicals. While the JRC supplied the technical equipment and protocols, the pesticide screening to be investigated and the monitoring scheme were co-designed with Coral Conservation group members, a local NGO. The pilot study collected new data on pesticide occurrence and their toxicity in the local tropical environment, complementing on-going studies in the region. The study found 23 pesticides, the majority of which are fungicides registered for use in banana cultivation (azoxystrobin, difenoconazole, fluopyram, thiabendazole). Cumulative pesticide concentrations ranged from 5.3 ng/L in the upper catchment of the Estrella River (E-a) to 954.9 ng/L in the lower catchment of the Sixaola River (S-c), where the highest individual compound concentration was also recorded for fungicide azoxystrobin (425.0 ng/L). At the sampling sites along the Carbon River and in the lower catchment of the Sixaola River, compounds fenamiphos, fenpropathrin and azoxystrobin were the main responsible for the elevated toxic units (Toxic Units >0.01) for crustacean daphnia magna. Beyond highlighting the link between agrochemical occurrences in surface waters and surrounding land use, the citizens' engagement aspect promotes alternative water quality monitoring methods, raising awareness and scientific literacy in local communities and underscoring the value of bottom-up approaches.

In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas Chromatography Quadrupole Time of Flight High Resolution Mass Spectrometry (GC-QToF-HRMS). The two extraction techniques were compared, among others, for their limits of detection, recovery, extraction, and quantification efficiency of pesticides, as well as spatial and temporal differences in detected compounds. The target compounds screened were pesticides belonging mainly to the categories of fungicides, insecticides, and herbicides. Although SBSE extracted more pesticides at two out of three sites, SPE extracted total concentrations up to four times higher than SBSE over all sampling sites. The log K_OW of detected pesticides only partially explained the differences in detection, with SBSE performing better in the absorption of hydrophobic compounds. In addition, matrix effects, in particular turbidity, appeared to hinder extraction of contaminants, especially for SBSE. Spatially, SBSE detected 10 pesticides more than SPE at two locations, while the opposite was true at the third location, where turbidity was higher. The types of pesticides detected varied slightly between techniques and locations. The study highlights the complementarity of SBSE and SPE for monitoring pesticides in natural environments. SBSE is an easy-to-use technique and allows for extraction of a higher number of pesticides at trace level, but it might not be the preferred option for highly turbid waters. SPE requires more tedious and complex sample processing but allows for a more accurate quantification of a broader range of pesticides.

The presence of pesticides in surface water samples from the Lake Naivasha catchment area in Kenya was investigated using Stir Bar Sorptive Extraction (SBSE) and Gas Chromatograph with Quadruple Time-Of-Flight High Resolution Mass Spectrometry (GC-QToF-HRMS). A total of 56 pesticides were detected, belonging to different classes including fungicides (48.2%), insecticides (17.9%), herbicides (12.5%), and other categories. The most frequently detected pesticides were the fungicides boscalid, fluopyram, hexachlorobenzene, tebuconazole, herbicide metolachlor, and insecticides bromopropylate, chlorpyrifos, diazinon, and the synergist piperonyl butoxide. The site with the highest pesticides detections was adjacent to Lake Naivasha, near a wastewater treatment plant discharge. Toxicological risk assessments revealed that the acute toxic unit threshold for crustaceans (TU = 0.01) was exceeded in several samples, primarily due to the presence of chlorpyrifos and diazinon. Notably, chlorpyrifos, banned for all agricultural purposes in Kenya in 2024, was detected in several samples. These findings highlight the presence of pesticides in Kenyan water bodies, posing potential risks to aquatic ecosystems and underscore a need for stricter regulation, ongoing monitoring, and the adoption of sustainable agricultural practices to minimise the impact of pesticides on the environment.

Pesticide contamination poses significant threats to both humans and the environment, with residues frequently detected in surface waters worldwide. This study compares the effectiveness of passive samplers (POCIS and Chemcatcher) and grab sampling coupled with Stir-Bar Sorptive Extraction (SBSE) and Solid-Phase Extraction (SPE) for monitoring pesticides in surface waters. The comparative study was conducted at three sites in Victoria, Australia, representing different land uses. A total of 230 pesticides were screened, with 79 different pesticides detected overall. SBSE extracted the highest number of pesticides from grab samples, followed by SPE and passive samplers. The study highlights the complementarity of different sampling and extraction techniques in detecting a wide range of pesticides. The study also explores the suitability of these techniques for citizen science applications, emphasizing the importance of selecting appropriate methods based on specific research objectives and available resources. The findings underscore the need for a tiered approach, combining passive samplers for initial screening and grab sampling for quantitative analysis, to develop a robust monitoring strategy for protecting water quality.

The study presents a comprehensive water quality data collection along the Gellibrand River catchment, over three monitoring campaigns conducted in 2024, to investigate pesticides occurrence. Citizen scientists, guided by the Royal Melbourne Institute of Technology (RMIT) University and the European Commission Joint Research Centre (JRC), deployed and retrieved passive samplers (n = 10), collected grab composite samples (n = 10) and conducted Stir Bar Sorptive Extraction (SBSE) of the latter, while Solid Phase Extraction (SPE) of all the other samplers was performed by a PhD student. All samples were screened by Gas Chromatography Quadruple Time of Flight High Resolution Mass Spectrometry (GC-QToF-HRMS) for 447 pesticides. Passive samplers provided qualitative information on the presence/absence of pesticides, while grab composite samples provided quantitative information in form of pesticides concentrations. Concentrations were used to calculate Toxic Units (TU) to assess potential ecological risks for crustaceans Daphnia magna . A total of 18 different pesticides were detected in the first campaign, followed by 8 in the second, and 15 in the third campaign. The two different extraction methods deployed, SPE and SBSE, revealed different compounds. Across the campaigns, fungicides emerged as the most frequently detected class, although most screened chemicals were insecticides. Temporal and spatial analyses highlighted significant variability in pesticide presence, influenced by factors like weather conditions and surrounding land use, in particular, forestry. The study’s ecological risk assessment identified potential toxicity risks to Daphnia magna from specific insecticides, such as carbaryl. The study successfully combined advanced sampling and extraction technologies with citizens participation, finding pesticides that are registered for and applied in surrounding forestry activities, providing valuable new insights regarding pesticides occurrence in Australia. Citizen scientists have been enthusiastically engaged in the collection, deployment, retrieval and extraction of samples. They contributed to communication and sharing of the results with the broader community, thus confirming the potential of citizen science to expand water quality monitoring capacity.