Water pollution is a significant problem that threatens human health around the world. Currently, more people every year die from drinking unsafe water than they do from war. The problem is not limited to developing countries; water pollution is a huge challenge for industrialized countries too.
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A recent report found that around half of the water supply in the US is too polluted for drinking, swimming, and fishing. Around half of tap water is contaminated with “forever chemicals”, exposure to which has been linked to cancer, liver damage, fertility issues, and more. The country’s waterways are severely polluted, and drinking systems across the US are failing to meet safety standards, which poses a significant threat to human health.
Here, we discuss some of the main sources of water pollution and how sensor technology has been developed to monitor each of these sources.
Sewage and Wastewater
An estimated 80% of the world’s wastewater is re-introduced back into the environment without being treated. This introduced harmful chemicals and bacteria into our environment, including water systems. Exposure to this sort of pollution can lead to negative health outcomes for marine life as well as humans.
Sensors have been used for many years to monitor levels of sewage and wastewater contamination in our water systems. In particular, optical sensors have been used in the US to detect and quantify bacteria in water supplies. Today, optical sensors are a common tool in water-quality management in the US.
Dissolved oxygen sensors are also popular in this field; they report the level of oxygen saturation within a water sample, which helps us to understand how much sewage and wastewater pollution has contaminated the water and how significant this impact may be on marine life.
Possibly the most significant source of water contamination across the globe is industrial waste. Industrial sites that do not have appropriate waste management processes end up introducing toxic chemicals and other pollutants into water systems, including freshwater systems. This can cause water to be unsafe to drink and dangerous for marine ecosystems. In extreme cases, it can lead to “dead zones” - areas of water that are so oxygen-deprived because of pollution can they can no longer sustain marine life.
Many sensors can be effectively leveraged to monitor how much water supplies have been affected by industrial waste. PH sensors are one of the most important sensors for monitoring water contamination caused by industrial waste. By introducing industrial waste into water sources, the pH of the water can drastically fall. This can significantly impact the delicate balance of microorganisms in the water. When the water pH becomes too low, fungi will outcompete bacteria, changing the microbial content of the water, which has a knock-on effect on aquatic ecosystems.
The agricultural industry heavily relies on chemical fertilizers and pesticides to maximize crop growth and protect crops from pests. There is a huge drawback to using chemicals in agriculture, however. When sprayed on crops, the chemicals not only enter the plants we eat, but they also enter the soil and surrounding environment. Chemicals can then leech from the soil into the groundwater and nearby freshwater sources such as rivers and streams.
To monitor agricultural run-off, sensors are deleted in rivers, lakes, and streams to measure the levels of chemicals, contaminants, and nutrients. This allows us to understand how agricultural run-off is impacting the environment and water systems. For example, nutrient sensors can be used to determine levels of nitrogen and phosphorus. These two nutrients are heavily used in fertilizers but can lead to water pollution in excessive amounts.
hemical sensors are also used to monitor levels of pesticides, herbicides, and fertilizers in the water. Water quality sensors are also commonly used to detect changes in pH, dissolved oxygen temperature and water conductivity.
Plastic Pollution in Our Oceans
Plastic pollution in our water systems presents an increasingly serious issue for our planet. Plastic never fully degrades; over the years, it breaks down into smaller and smaller particles, forming microplastics. Recent research has found alarming levels of microplastic in our water sources. Microplastics have also been found in fish, fruit and vegetables, and even within human organs. Exposure to microplastic has been linked with diseases such as cancer.
Various sensors have been deployed to monitor levels of plastic pollution in our oceans. Sonar sensors can be used to scan the ocean floor and identify larges pieces of plastic debris. Acoustic sensors can also be used in a similar way. Imaging sensors are also used to investigate the nature of plastic pollution in a body of water, such as the type of plastic and its impact on marine life.
Volcanoes and Earthquakes
Natural sources such as volcanoes and earthquakes can also contribute to water pollution. Volcanic ash can fall into water sources and increase water turbidity. Volcanic ash can also add heavy metals such as cadmium, copper, and arsenic to water sources. Earthquakes can also introduce sediment into the water due to the intense shaking of the earth.
Sediment and particle sensors can monitor the levels of ash, rock fragments, and other debris released following a volcano eruption or earthquake.
References and Further Reading
Jen Christensen. (2023). Nearly half of the tap water in the US is contaminated with ‘forever chemicals,’ government study finds [online]. CNN. Available at: https://edition.cnn.com/2023/07/05/health/pfas-nearly-half-us-tap-water-wellness/index.html#
Lynne Peeples. (2020). ‘We’ve always known ours was contaminated’: the trouble with America’s water [online]. The Guardian. Available at: https://www.theguardian.com/us-news/2020/sep/15/america-water-crisis-contamination-pollution-infrastructure
Shirin Ali. (2022). About half of US water ‘too polluted’ for swimming, fishing or drinking, report finds [online]. The Hill. Available at: https://thehill.com/changing-america/sustainability/environment/600070-about-half-of-us-water-too-polluted-for-swimming/
Water Pollution: Everything You Need to Know [online]. NRDC. Available at: https://www.nrdc.org/stories/water-pollution-everything-you-need-know
Wygel, C.M. et al. (2019) ‘Bubbles and dust: Experimental results of dissolution rates of metal salts and glasses from volcanic ash deposits in terms of surface area, chemistry, and human health impacts’, GeoHealth, 3(11), pp.338–355. doi:10.1029/2018gh000181.
6 Most Common Causes of Water Pollution [online]. Earth.org. Available at: https://earth.org/what-are-the-causes-of-water-pollution/