➀ The article discusses a citizen science project focused on water quality monitoring, particularly the detection of nitrates and pesticides. ➁ Pesticides, being a complex mix of hundreds of chemicals, require advanced techniques like chromatography and mass spectrometry for detection, which are not feasible for citizen scientists. ➂ The author inquires if any organization is developing an electronic pesticide sensor that could enable on-the-spot testing and potentially allow for permanent monitoring setups using low-power wireless technologies.