Human Activities: Polluting Our Water Supplies

Human activities have a detrimental impact on water supplies, causing water pollution and contamination. Water pollution occurs when harmful substances, such as chemicals, waste, microplastics, and other pollutants, contaminate bodies of water, degrading water quality and making it toxic for humans and the environment. This is caused by a range of human activities, including agriculture, industrial production, fossil fuel production, and urbanization, which lead to the contamination of water sources. Additionally, human-induced changes to the nitrogen cycle, pharmaceutical products, and unregulated chemicals further contribute to water pollution. The degradation of water supplies poses a serious threat to public health, ecosystems, and water accessibility, requiring costly treatments and protection measures.

Industrial and agricultural waste

Industrial waste is defined as waste generated by manufacturing or industrial processes. It includes cafeteria garbage, dirt and gravel, masonry and concrete, scrap metals, trash, oil, solvents, chemicals, weed grass and trees, wood and scrap lumber, and similar wastes. Industrial solid waste can be solid, liquid, or gas held in containers, and it is divided into hazardous and non-hazardous waste. Hazardous waste may result from manufacturing or other industrial processes, and it can include commercial products such as cleaning fluids, paints, or pesticides.

Water pollution from industrial waste is concentrated within a few subsectors, mainly in the form of toxic wastes and organic pollutants. A large portion can be traced back to the processing of industrial chemicals and the food products industry. Many major industries have treatment facilities for industrial effluents, but small-scale industries often cannot afford the necessary investments in pollution control equipment.

Shale gas extraction, for example, produces large volumes of wastewater that can contain high concentrations of dissolved solids (salts), naturally occurring radionuclides, metals, and other pollutants used in drilling. Mining operations can also generate tailings and waste rock, leading to wastewater discharges that affect surface and groundwater quality, drinking water supplies, and even air quality.

Agricultural activities, such as farming, clearing forests, and building roads, can also contribute to water pollution. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. Veterinary medicines, antibiotics, vaccines, and growth promoters are newer sources of agricultural pollution, moving from farms through water to ecosystems and drinking water sources.

Nitrate from agriculture is now the most common chemical contaminant in groundwater aquifers worldwide. Fish excreta and uneaten feeds from aquaculture also diminish water quality, and the increased use of antibiotics, fungicides, and anti-fouling agents may contribute to polluting downstream ecosystems.

To address these issues, integrated farming systems can help optimize resource use and reduce pollution by ensuring that waste from one enterprise becomes input for another. Buffer strips, or vegetated filter strips along farms and rivers, are also effective in decreasing pollutant concentrations entering waterways.

Pharmaceuticals and chemicals

Pharmaceuticals enter water supplies through human excretion and by drugs being flushed down toilets. Wastewater treatment plants are unable to filter out many pharmaceutical compounds, allowing these chemicals to seep into freshwater systems and oceans. A 2017 UNESCO study found that only nine out of 118 assessed pharmaceuticals were removed from wastewater during treatment, with an efficiency of over 95%. This inefficiency allows pharmaceuticals to enter the water supply, impacting aquatic life and potentially human health.

The impact of pharmaceuticals on aquatic life is evident, with numerous studies showing that chemicals can alter the hormone systems of fish, leading to changes in secondary sexual characteristics and potential reproductive failure. Estrogen and estrogen-like chemicals from birth control pills, postmenopausal treatments, and natural excretion have been found to feminize male fish and alter female-to-male ratios. Antidepressants have also been found in the brain tissue of fish downstream from wastewater treatment plants.

In addition to pharmaceuticals, chemicals from personal care products, such as perfumes, colognes, skin lotions, and sunscreens, also contribute to water pollution. These products wash off people's skin and enter water systems, adding to the chemical burden.

Agricultural practices are another source of chemical pollution, with antibiotics used as growth enhancers in livestock contributing to the issue. Manure containing traces of pharmaceuticals is often spread on land as fertilizer, allowing it to leach into local streams and rivers.

While the impact on human health from pharmaceuticals in the water is uncertain, there are concerns about potential cumulative effects, especially considering the presence of detectable levels of pharmaceuticals in drinking water supplies.

Climate change

The warmer air that comes with climate change can hold more moisture than cool air. Consequently, in a warmer world, the air will suck up more water from oceans, lakes, soil, and plants. The drier conditions left behind could negatively affect drinking water supplies and agriculture. On the other hand, the warmer, wetter air could also endanger human lives. A study out of Columbia University's Lamont-Doherty Earth Observatory found that higher humidity will make future higher temperatures unbearable in some places by blocking the cooling effects of sweat.

As the ice sheets and mountaintop glaciers melt due to rising temperatures, they dump extra water into the oceans, causing sea levels to rise and jeopardizing coastal properties worldwide. Climate scientist Richard Seager from Columbia's Lamont-Doherty Earth Observatory has found that higher ocean surface temperatures could make rainfall more variable and thus less predictable from year to year.

There are many things that can be done to lessen the impact of climate change on water supplies. On an individual level, people can grow their own fruits and vegetables or buy locally grown produce, as produce transported from far away by trucks adds more carbon dioxide to the atmosphere. People can also walk or ride a bike instead of driving a car. On a larger scale, industries that are dependent on fossil fuels need to switch to renewable, cleaner energy sources.

Deforestation and mining

Deforestation

Forested land surrounding a body of water plays a critical role in maintaining water quality and accessibility. Trees absorb carbon dioxide and release oxygen back into the environment, helping to regulate rainfall and evaporation. Deforestation results in carbon accumulation in the atmosphere, contributing to rising global temperatures and leading to irregular rainfall, including droughts and flooding.

A study in Malawi found that a 1% increase in deforestation resulted in a nearly 1% decrease in access to clean water, equivalent to a 9-10% decrease in rainfall. The country lost 14% of its forest between 2000 and 2010, reducing the availability of clean drinking water for its citizens. Globally, we have lost one-third of the world's forests, an area twice the size of the United States, with the Amazon Rainforest shrinking by 18% in the last 40 years.

Mining

Mining consumes, diverts, and pollutes water resources. It affects freshwater sources through its heavy use of water in processing ore and through water pollution from discharged mine effluent and seepage from tailings and waste rock impoundments. The Canadian mineral industry, for example, generates one million tonnes of waste rock and 950,000 tonnes of tailings per day, totaling 650 million tonnes of waste per year. This waste rock often contains acid-generating sulphides, heavy metals, and other contaminants, which can leach into nearby water sources.

Acid Mine Drainage (AMD) occurs when sulphides in rocks are exposed to air and water, producing sulphuric acid. AMD severely degrades water quality, killing aquatic life and rendering water unusable. Heavy metal contamination further pollutes water sources when metals such as arsenic, cobalt, copper, cadmium, lead, silver, and zinc come in contact with water.

Urban growth and development

One of the key challenges in urban areas is the lack of access to basic services, particularly in informal settlements. Inadequate sanitation infrastructure and the discharge of untreated wastewater into local water bodies are significant sources of pollution. The high population density in urban areas intensifies this problem, as the volume of wastewater generated can overwhelm existing treatment facilities, leading to the contamination of water sources.

Urban development also influences water supply and demand dynamics. The expansion of cities, particularly in the form of urban sprawl, can lead to increased water consumption and contribute to water shortages. The imbalance between water supply and demand can be further exacerbated by climate change, with droughts and reduced rainfall affecting water availability. Additionally, the depletion of groundwater through over-pumping can result in the emergence of sinkholes, posing risks to densely populated urban areas.

The quality of water in urban areas is also impacted by various contaminants stemming from urban surfaces, industry, agriculture, and untreated domestic wastewater. These contaminants include heavy metals, nutrients such as sodium, nitrate, and phosphorus, microbial contaminants, synthetic chemicals, pesticides, pharmaceuticals, and volatile organic compounds (VOCs). The discharge of these pollutants into water bodies can have profound effects on aquatic ecosystems and pose risks to human health, especially in developing countries where regulatory policies may be lacking.

To address these issues, sustainable urban planning and water management practices are essential. This includes investing in wastewater treatment infrastructure, promoting water conservation, and implementing regulations to control pollutant emissions. By prioritizing water and sanitation interventions, cities can improve public and environmental health, reduce the vulnerability of water supply systems, and ensure a more resilient future in the face of climate change and population growth.

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