The Earth's Polluted Water Crisis: How Much Is Lost?

Water is essential for human survival, yet water pollution is a widespread and growing problem. Water covers 70% of the Earth's surface, but only 3% of this water is freshwater, with the remaining 97% being too salty for drinking, agriculture, and most industrial uses. Of this 3% of freshwater, two-thirds is locked away in glaciers, polar ice caps, the atmosphere, and soil, or lies too far underground to be extracted affordably. This leaves less than 1% of the Earth's freshwater readily accessible to humans. However, even this limited supply is under threat from pollution. Agricultural runoff, industrial waste, and untreated human wastewater are all significant contributors to water pollution, with pesticides, fertilizers, and toxic chemicals contaminating rivers, lakes, and aquifers, rendering them unfit for human use. Climate change further exacerbates water scarcity by altering weather patterns and causing droughts and floods. As a result, an estimated 1.1 billion people worldwide lack access to water, and water pollution claims more lives annually than war and all other forms of violence combined.

Water pollution sources: agriculture, industry, and municipal waste

Water is a "universal solvent", meaning it can dissolve more substances than any other liquid on Earth. This makes water uniquely vulnerable to pollution. Water pollution is a widespread problem that jeopardizes our health. In fact, unsafe water kills more people each year than war and all other forms of violence combined.

Agriculture

The agricultural sector is the biggest consumer of global freshwater resources. Farming and livestock production use about 70% of the Earth's surface water supplies. However, agriculture is also a serious water polluter. Globally, agriculture is the leading cause of water degradation. In the US, agricultural pollution is the top source of contamination in rivers and streams, the second-biggest source in wetlands, and the third main source in lakes.

Every time it rains, fertilizers, pesticides, and animal waste from farms and livestock operations wash nutrients and pathogens (such as bacteria and viruses) into our waterways. Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, is the number-one threat to water quality worldwide. This can cause algal blooms, a toxic soup of blue-green algae that can be harmful to people and wildlife. Increased levels of nitrogen and phosphorus from fertilizer and manure can stimulate algal blooms in lakes and rivers, leading to hypoxic (low-oxygen) conditions that are harmful to aquatic life.

Soil erosion, nutrient loss, bacteria from livestock manure, and pesticides constitute the primary stressors to water quality. Rainfall and snowmelt transport the majority of these pollutants to surface waters, but other factors, such as cattle loafing in stream corridors, can also contribute to water degradation.

Industry

Industrial water pollution is a major problem for waterways. It makes rivers and lakes unswimmable and leads to everything from deadly algae blooms to mutations in freshwater wildlife. In 2021 alone, US oil refineries discharged 60,000 pounds of selenium, which causes mutations in fish. These refineries also discharged nearly 16 million pounds of nitrogen, creating algae blooms that suck oxygen from the water and kill fish. Organic chemical and plastic plants release millions of pounds of pollutants each year, including nitrogen, the carcinogen benzene, and lead.

Municipal Waste

Municipal wastewater is mainly composed of organic matter, suspended solids, and pathogens. The size range of organic matter in wastewater can range from less than 0.001 μm to over 100 μm. The main pollutants discharged into water streams are organic and solid matter. Municipal wastewater is linked to the water supply consumption of inhabitants and of municipal and security services (watering, washing). Wastewater flow varies according to the season of the year, weather conditions, day of the week, and time of day.

Finite freshwater: less than 1% of accessible, usable water

Water is a finite resource, and less than 1% of the earth's freshwater is accessible and usable by humans. This small fraction of freshwater is critical for communities worldwide, and its limited availability contributes to water stress and insecurity.

The majority of the earth's water (about 71%) is saline and found in oceans, which is unsuitable for drinking, irrigation, and most industrial uses. Of the remaining 2.5% of freshwater, a significant portion is locked away in glaciers, polar ice caps, and underground water sources, known as groundwater. Groundwater is an important natural resource, providing drinking water and irrigation for agriculture, but it is vulnerable to pollution from contaminants such as pesticides, fertilizers, and waste.

The accessibility of freshwater is further reduced by geographical and climate factors. Brazil, Russia, Canada, Indonesia, China, Colombia, and the United States possess most of the world's surface freshwater resources, while many countries in Africa and Asia face water scarcity. According to the United Nations, 2.1 billion people lacked access to safe drinking water in 2017, relying on contaminated water sources that pose health risks.

Agricultural activities are the biggest consumers of global freshwater resources, accounting for about 70% of freshwater usage. However, agriculture is also a significant contributor to water pollution. Fertilizers, pesticides, and animal waste from farms wash into waterways during rainfall, leading to nutrient pollution and toxic algal blooms. Industrial discharge and municipal waste also play a role in polluting water sources, making them unsafe for human use.

The demand for freshwater is projected to increase by 50% by 2050, driven by population growth and increasing agricultural needs. This will further strain the earth's limited freshwater supplies and intensify the challenges of water insecurity and pollution.

Pollution from agriculture: phosphorous, nitrogen, and animal waste

Although the exact figure of how much of Earth's water is too polluted for use is unclear, it is known that water pollution is a widespread problem that is jeopardizing our health. Less than 1% of the Earth's freshwater is accessible to us, and without action, the challenges will only increase by 2050 when global demand for freshwater is expected to be one-third greater than it is now.

Agriculture is a serious water polluter, and the leading cause of water degradation worldwide. The agricultural sector is the biggest consumer of global freshwater resources, with farming and livestock production using about 70% of the Earth's surface water supplies.

Phosphorus

Phosphorus is a critical nutrient for plant growth, and it occurs naturally in soil. For centuries, farmers have added extra phosphorus to their fields to boost harvests. However, phosphorus overuse has led to water pollution and shortages. Phosphorus runoff from farms contributes to widespread water pollution, and unused phosphorus fertilizer can build up in the soil, causing environmental problems long after its application. Even small amounts of phosphorus runoff from farms and sewage are enough to fuel algal blooms that fill waterways with festering green scum, producing toxins that can foul drinking water and kill fish and other aquatic life.

Nitrogen

Nitrogen is another key plant nutrient. However, when nitrogen is not fully utilized by growing plants, it can be lost from farm fields and negatively impact air and downstream water quality. High levels of nitrogen in water bodies can cause eutrophication, leading to hypoxia ("dead zones") and a decrease in aquatic life.

Animal Waste

Animal waste from farms and livestock operations can wash nutrients and pathogens (such as bacteria and viruses) into waterways. Waste from concentrated animal feeding operations (CAFOs) presents a significant risk to water quality due to the increased volume of waste and the presence of contaminants such as antibiotics and other veterinary drugs.

Groundwater pollution: from pesticides to landfill waste

Water is a "universal solvent", meaning it can dissolve more substances than any other liquid on Earth. This makes it extremely vulnerable to pollution. Of all the water on Earth, 97% is found in the oceans, which are too salty for drinking, crop irrigation, and most industrial uses. Of the remaining 3% of freshwater, 2.5% is unavailable, either because it is locked in glaciers, polar ice caps, the atmosphere, and soil, or because it is too polluted or too deep to be extracted affordably. This leaves only 0.5% of the Earth's water as available freshwater.

Groundwater, which is water that infiltrates the ground through porous materials and fills underground rock layers known as aquifers, is one of our most important natural resources. In the US, more than half of the population gets their water from groundwater, and for some in rural areas, it is their only freshwater source.

Groundwater is susceptible to pollution from various sources, including pesticides and landfill waste. Pesticides are widely used in agricultural, non-crop, and urban areas to control insects, weeds, and other organisms that attack food crops. While they have helped increase food production, they also have potential adverse effects on the environment and human health. Pesticides can contaminate groundwater through various pathways, including applications to crop fields, seepage of contaminated surface water, accidental spills and leaks, improper disposal, and injection of waste material into wells. The effects of pesticide use on groundwater quality may take decades to become apparent.

In Europe, the Water Framework Directive (WFD) and its daughter directives set environmental quality standards for pesticides in surface water and groundwater. The Eighth Environment Action Programme aims for zero pollution from harmful chemicals, including pesticides, in air, water, and soil. The Groundwater Directive sets a precautionary quality standard of 0.1µg/L for pesticides, reflecting the desire to keep pesticide concentrations low. Despite these efforts, between 2013 and 2022, one or more pesticides were detected above the effect threshold in 9% to 25% of surface water monitoring sites.

Landfill waste is another significant source of groundwater pollution. The age of the waste was found to be the most determining factor in the degree of groundwater pollution, with older landfills showing decreased concentrations of contaminants. Closing landfills also helps improve water quality. However, groundwater reservoirs are still threatened globally, mainly by anthropogenic activities, and there is a need to understand how remediation efforts can be influenced by site-specific factors.

Water scarcity: climate change, agriculture, and industrial waste

Water scarcity is a significant global issue, with climate change, agriculture, and industrial waste playing pivotal roles in its exacerbation. Firstly, climate change severely impacts water availability and quality. Rising temperatures disrupt precipitation patterns, leading to unpredictable rainfall, shrinking ice sheets, rising sea levels, and more frequent floods and droughts. These climate-related hazards not only affect water scarcity but also jeopardize water-related infrastructure and sanitation systems, further compounding the challenges of water access and management.

Agriculture, a vital sector for global food security, is heavily dependent on water. Approximately 70% of freshwater is used for agriculture, and with a growing global population, the demand for food and water for agricultural purposes continues to surge. Inefficient irrigation systems and water management practices in agriculture contribute to water scarcity. Rainfed agriculture, the most common method in developing nations, relies on inconsistent rainfall, often requiring supplemental irrigation. While efforts to improve water management in agriculture, such as drip irrigation and water harvesting techniques, are underway, the increasing population's demand for food intensifies the pressure on water resources.

Industrial activities, driven by the escalating demand for goods, have led to a surge in industrial waste. This waste contains a range of hazardous contaminants, including heavy metals, pesticides, plastics, and chemical wastes, which are released into water bodies, causing severe water pollution. The discharge of untreated or inadequately treated industrial wastewater has detrimental ecological and human health consequences, including waterborne diseases and ecological disruptions.

The scarcity of clean water and the escalating population drive the need for sustainable practices in industrial processes. Several treatment plants employ chemical, electrochemical, biological, and physical processes to treat industrial wastewater and make it potable. Additionally, economic growth considerations prompt industrial developers to adopt technologies that promote cleaner production, reduce water consumption, and curb pollution.

In conclusion, water scarcity is intricately linked to climate change, agriculture, and industrial waste. Addressing these interconnected challenges requires a multifaceted approach, including climate change mitigation, improved water management practices in agriculture, and the implementation of sustainable industrial processes that minimize water consumption and pollution. By tackling these issues, we can help alleviate water scarcity and ensure sustainable access to this precious resource for current and future generations.

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