Hazardous chemicals in waterways - The chemicals found in waterways are typically a result of urban storm water run-off, industrial discharge and improper waste disposal, threatening aquatic life and public health. These chemicals include herbicides, pesticides, heavy metals, agricultural nutrients (nitrates and ammonia), PFAs and polychlorinated biphenyls (PCBs) (Iowa PBS, 2015).
Ammonia (NH3) - Ammonia is a covalent chemical compound consisting of one nitrogen atom and three hydrogen atoms. It is held together with hydrogen bonds, and due to its extreme polarity it is highly soluble in water. Ammonia enters waterways through natural processes such as decaying plants and animal waste, as well as human activities such as agricultural nitrogenous fertilizer run-off, industrial discharge and leaking domestic sewage (Australian Government Initiative 2000).
Why is it hazardous? - Ammonia is hazardous in waterways as it is directly toxic to fish and aquatic life, damaging their gills, nervous systems and organs. It can also trigger massive algal blooms through a process called eutrophication, which can suffocate aquatic ecosystems. This occurs as ammonia acts as a fertilizer to species of algae, therefore excessive levels of ammonia in the water trigger the algae to rapidly reproduce and accumulate on the surface of the water. These algae blooms block sunlight, preventing underwater plants from photosynthesizing and therefore, oxygen levels in the water deplete and kill fish and aquatic animals (Soler et al. 2021).
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Glyphosate - Glyphosate is a broad spectrum, non-selective chemical herbicide used to kill weeds and grasses, operating systemically through the plant down to the roots. It is widely used in agricultural practices. It is present in many forms, including an acid and several salts (National Pesticide Information Center 2019). Glyphosate is an organophosphorus compound and substituted amino acid with the molecular formula C3H8NO5P. Its chemical name is N-(phosphonomethyl) glycine, consisting of a central secondary amine connected to a glycine carboxylic acid group on one side and a phosphonate group on the other (PubChem 2019).
Why is it hazardous? - Glyphosate is hazardous in waterways because commercial formulations and breakdown products harm aquatic life, bind to sediments to persist longer, and disrupt vital food chains through runoff and spray drift. Commercial mixtures commonly contain chemical additives like tallowamines or other surfactants which are commonly more toxic than glyphosate itself (Mitchell et al. 2026).
Limitation of Measurement - A commercial mix of glyphosate will be difficult to identify in water as it is most likely made up of various chemicals. Therefore, it will be difficult to pinpoint the single chemical in the solution and determine the presence of glyphosate in the solution.
Polychlorinated Biphenyls (PCBs) - PCBs are toxic man-made mixtures of various isomers based on biphenyl and carbon chlorine compounds, once widely used as electrical coolants, lubricants and paint additives. They persist in the environment and bioaccumulate in the food chain. It was banned globally under the Stockholm Convention on Persistent Organic Pollutants in 1975, however it is still present in waterways, soil and animal fat (Department of Climate Change, Energy, the Environment and Water, 2026).
Why is it hazardous? - PCBs possess long-standing environmental effects due to their inability to be easily broken down. They have a strong chemical structure featuring dual carbon ring bonded with multiple chlorine atoms. The chlorine atoms lock onto the biphenyl ring and block natural enzymes or chemical attacks required to break down the structure (Borja et al. 2005). Additionally, PCBS are a threat to humans and animals, as contact with it causes skin conditions like chloracne, liver damage and immune system harm. It is classified as a probable human carcinogen (National Library of Medicine, 2000).
Limitation of Measurement - PCBs are often composed of many elements and typically are of very low levels in the water. The concentration techniques (such as solid-phase microextraction) are not possible to do in school lab settings (Hou et al. 2022).