River Pollution: Causes And Concerns

Rivers are a vital natural resource, but they are increasingly under threat from pollution. Water pollution is a global issue, with human activity being the most common cause of poor water quality. Rivers are particularly susceptible to contamination from industrial waste, agricultural chemicals and pesticides, oil spills, and urban runoff. These pollutants can have devastating effects on the health of humans, animals, and the environment, as well as the economy. With only 14% of rivers and lakes in England achieving 'good ecological status', it is clear that river pollution is a pressing issue that requires urgent attention and action.

Industrial waste

The manufacturing, mining, and waste disposal industries are among the worst water polluters. Chemical companies, utilities, plastics and rubber manufacturers, and petroleum and coal producers are the top five industries releasing contaminants into water bodies. These industries discharge toxic substances such as ammonia, nitrates, arsenic, lead, mercury, and chromium into rivers and other water sources. For example, the now-defunct Diamond Alkali Co. in New Jersey, polluted the Passaic River, a drinking water source for millions, with chemicals used to make Agent Orange.

In addition to chemical pollutants, industrial waste can also include oil spills and leaks. Oil forms a film on the water surface, preventing oxygen from entering and harming aquatic life. Oil spills often result from drilling operations or oil transportation. Furthermore, industrial wastewater can contain harmful microorganisms, which, when released into rivers, can breed diseases and cause health issues in humans and animals.

The illegal discharge of industrial wastewater is a significant issue, especially in emerging countries with rapidly growing industrial sectors, such as China, India, Africa, and South America. Inconsistencies in implementing and monitoring environmental legislation have led to the everyday occurrence of untreated wastewater being discharged into rivers and lakes in these regions. Even in developed countries like the USA, laws do not cover all types of industrial wastewater pollution.

Agricultural pollution

Agriculture is a major source of river pollution, with farming practices causing widespread environmental problems in rivers. According to a 2020 report by the Environment Agency, agricultural runoff is the biggest single polluter of rivers, responsible for about 40% of the damage to UK waterways.

Fertilisers and animal waste from farms contain high levels of nitrogen and phosphorus. When these substances are washed into rivers, they cause excessive growth of algae, a process called eutrophication. This algae bloom can deplete the oxygen in the water, leading to the death of many aquatic animals. The algae are then broken down by bacteria, which further reduces the oxygen levels in the water. This process can cause the death of many more organisms, impacting the entire river ecosystem, including fish, plants, and birds.

Farmers also use various chemicals and pesticides to protect their crops from insects and bacteria. These chemicals can seep into the groundwater and contaminate rivers, causing harm to animals, plants, and humans. In addition, the use of nutrient-rich materials to improve soil quality can also contribute to river pollution. When it rains, these nutrients can be washed into waterways, further exacerbating the problem of eutrophication.

To address agricultural pollution, legislation such as the Environment Act and farming rules for water have been introduced in the UK. These rules focus on the proper storage and distribution of animal waste and fertilisers to prevent pollutants from running into rivers. However, violations of these rules remain a significant issue, with many farms continuing to operate in ways that contribute to river pollution.

Urban and transport runoff

Stormwater runoff is a major issue, particularly in areas where land use is changing from rural to urban activities. As stormwater passes over developed land, it collects pollutants such as litter, petrol, pesticides, and pollutants from oil spills, tyre wear, and brake wear. These pollutants are then carried into nearby waterways, contaminating rivers, streams, and lakes. In the US, stormwater runoff has caused significant damage to water bodies, leading to the closure of shellfish growing beaches, swimming beaches, and the contamination of drinking water supplies.

Vehicular transportation is a significant source of urban runoff pollution. Atmospheric deposition, which includes emissions from vehicles, has been identified as a major contributor to stormwater pollution. Oil leaks and spills from vehicles can also contaminate waterways, forming a film on the water surface that prevents oxygen from entering, harming aquatic life. Additionally, the wear and tear of vehicle tyres and brakes can generate pollutants that are washed into rivers by rainwater.

To mitigate urban and transport runoff pollution, it is essential to implement source controls and adopt sustainable practices. Individuals can play a role by properly maintaining their vehicles, recycling used oils and fluids, fixing oil leaks, and reducing their car usage. Communities can also work together to prevent stormwater runoff during urban development and ensure that pollutants are not dumped into storm drains.

Furthermore, the impact of urban runoff pollution extends beyond the immediate contamination of water bodies. Pollutants from urban environments can disrupt the delicate balance of ecosystems, harm wildlife, and have negative consequences for human health and various economic sectors, including commercial fishing, recreational businesses, and tourism.

Abandoned metal mines

The main pollutants from abandoned mines are heavy metals and acidic water. Metals such as lead, cadmium, zinc, copper, nickel, arsenic, and iron can contaminate rivers, making them harmful to humans, animals, and plants. These metals can enter the water in high concentrations, immediately killing fish and other animals. They can also enter the food chain, accumulating to toxic levels and eventually killing birds, fish, and mammals.

Acid mine drainage is another issue associated with abandoned metal mines. Acidic water can be released from the mines, turning rivers orange and making them highly acidic. In one example, the Wheal Jane mine in Cornwall, which closed in 1991, released 50 million litres of extremely acidic water in a single day, turning the nearby river and estuary orange and polluting them with harmful metals.

The Water and Abandoned Metal Mines (WAMM) programme, a partnership between the Environment Agency, the Coal Authority, and Defra, is working to address this issue. They currently operate four successful mine water treatment schemes, improving water quality in more than 30km of rivers. These schemes aim to capture metals in mine water before they enter rivers, using natural chemical and biological reactions.

While legislation has been passed to address this issue, the scale of the problem is significant. It is estimated that up to 40 new mine water treatment schemes are needed to halve the length of rivers polluted by abandoned metal mines by 2038, as targeted by the Environmental Improvement Plan.

Sewage and landfills

Sewage systems are particularly vulnerable to overflow during heavy rainfall, when the volume of water can exceed the system's capacity. This results in the discharge of untreated or partially treated sewage into nearby rivers. The issue is exacerbated by outdated infrastructure, as many older cities' sewage networks were not designed to handle increased volumes of water that come with heavy rain. Climate change is also a contributing factor, as more frequent and intense rainfall events are predicted, increasing the likelihood of sewage overflows.

The impact of sewage pollution on rivers is severe. High concentrations of pollutants, such as cyanide, zinc, lead, copper, and mercury, can kill fish and other aquatic animals immediately upon contact. These pollutants can also enter the food chain, accumulating to toxic levels and causing the deaths of birds, fish, and mammals. Sewage can also lead to eutrophication, where increased levels of nitrate and phosphate from farm waste cause a rapid increase in algae growth. When the algae die, they are broken down by bacteria, which consume the oxygen in the water, leading to the death of many aquatic organisms.

Landfills also contribute to river pollution, particularly when waste leaches into nearby groundwater, which can then spread contamination to rivers and other water bodies. This waste can contain harmful chemicals and pollutants, such as pesticides and fertilizers, which can have detrimental effects on aquatic life and render groundwater unsafe for human use.

It is important to address sewage and landfill pollution to protect the health of our rivers and ensure safe drinking water for communities. This requires investing in wastewater infrastructure, improving sewage treatment processes, and implementing sustainable practices to prevent spills and overflows. By taking these steps, we can reduce the impact of sewage and landfills on our precious river ecosystems.

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