Fertilizers: Water Pollution's Hidden Cause?

Fertilizers are essential for plant growth, but they can also be a significant source of water pollution. Excessive use of fertilizers, especially synthetic fertilizers, can have detrimental effects on water bodies and the environment. When fertilizers are not properly absorbed by plants or soil, they can be washed away by rainwater or irrigation, leading to fertilizer runoff. This runoff carries fertilizers into nearby water bodies, causing an overload of nutrients, particularly nitrogen and phosphorus.

The presence of excess nutrients in water leads to a process called eutrophication, where there is rapid and excessive growth of algae and other aquatic plants. This algal bloom reduces water clarity and blocks sunlight from reaching other aquatic plants. As the algae decompose, they consume oxygen, leading to oxygen depletion in the water, known as hypoxia. This can result in the death of fish and other aquatic organisms, creating dead zones in the water bodies.

Additionally, certain types of algae produce toxins that are harmful to fish, shellfish, and even humans. High levels of nitrates in drinking water can cause serious health issues, such as methemoglobinemia or blue baby syndrome in infants.

Fertilizer runoff also contributes to ocean acidification, which interferes with the shell-building abilities of marine organisms.

To prevent fertilizer runoff and its adverse effects on water quality, it is essential to apply fertilizers properly, use slow-release fertilizers, and avoid over-watering or over-fertilizing lawns. It is also crucial to keep fertilizers away from water sources and use the correct type and amount of fertilizer.

Eutrophication

Algal blooms can have several negative impacts on the environment and human activities. They reduce water clarity and harm water quality by limiting light penetration and growth of other plants. The excessive growth of algae and aquatic plants also consumes oxygen in the water, creating hypoxic or anoxic conditions that can lead to fish kills and the degradation of habitats for aquatic organisms. Eutrophication can also affect human activities such as fishing, boating, and swimming, and it can impact drinking water sources by releasing toxins that are harmful to humans and animals.

The introduction of algae-inhibiting organisms, such as shellfish and seaweed, can help reduce nitrogen pollution and control the growth of cyanobacteria, the main source of harmful algae blooms. Additionally, minimizing nutrient pollution from sewage and agriculture is crucial for preventing and reversing eutrophication. This includes improving waste disposal technology and adopting sustainable agricultural practices to minimize soil runoff and the use of nitrogen-based fertilizers.

Algal blooms

Algae are photosynthetic organisms that feed on nutrients like nitrogen and phosphorus, leading to massive "blooms" of organisms. These blooms are fuelled by fertilizer and manure runoff from farms and other animal facilities. Algae grow out of control, reducing the clarity and visibility of the water. This, in turn, reduces photosynthesis by aquatic plants, therefore reducing the oxygen in the water.

Some forms of blue-green algae can be toxic. Repeated algae blooms can create green-coloured lakes with low oxygen, which can result in fish kills or depleted water habitats for fish, wildlife, and humans. They can also degrade drinking water supplies and create other environmental nuisances.

To reduce algal blooms, individuals can play a role in reducing nutrient pollution by using fertilizers wisely, such as only when lawns show nutrient deficiencies, and avoiding use just before rain.

Water contamination

Fertilizers are a type of nutrient pollution and can cause significant damage to waterways. They can kill marine life, degrade water quality, and even lead to the destruction of ecosystems. Fertilizers are usually composed of nitrogen, phosphorus, and potassium, which are essential nutrients for plant growth. However, when there is an excess of these chemicals, they can contaminate water bodies and lead to harmful algal blooms, a process known as eutrophication. This reduces oxygen levels in the water, creating "dead zones" where marine life cannot survive.

Sources of Fertilizer Runoff

• Excessive irrigation or watering of lawns and agricultural land can cause fertilizer runoff, as the water carries the chemicals into nearby water bodies.
• Improper disposal of yard waste, such as leaving grass clippings on sidewalks or roads, can lead to fertilizer runoff during rain or irrigation.
• Using too much fertilizer can saturate the soil, causing the excess chemicals to run off into water bodies.
• Applying fertilizer to frozen or partially thawed ground can result in runoff, as the fertilizer cannot penetrate the soil effectively.

Preventing Fertilizer Runoff

To reduce the impact of fertilizer runoff and protect water sources, it is essential to:

• Use slow-release fertilizers that provide a controlled release of nutrients, matching the growth rate of plants.
• Keep fertilizer away from water sources, such as streams or lakes, to minimize the risk of nutrient pollution.
• Apply the correct amount of fertilizer by checking the NPK (nitrogen, phosphorus, and potassium) values on the package and using only what is needed.
• Leave lawn clippings on the lawn to return nutrients to the soil and help absorb water, preventing runoff.
• Set mower blades higher to encourage taller grass, which can absorb more water and reduce runoff.

Health Risks of Contaminated Water

Contaminated water can pose significant health risks, especially to infants and young children. Here are some of the potential health consequences:

• Methemoglobinemia or "blue baby syndrome," caused by high levels of nitrates in drinking water, can lead to oxygen deprivation and turn an infant's skin blue.
• Algal blooms can produce toxins that, when ingested, can cause skin and respiratory irritation, impaired organ function, and other severe symptoms.
• Pesticides in water can have adverse effects, including cancer, endocrine disruption, and neurological damage.
• Water contaminated by wastewater can lead to various diseases, including cholera, typhoid, and dysentery.
• Animal waste in water can transmit pathogens such as E. coli, Salmonella, and Giardia, causing gastrointestinal illnesses.

Nitrate poisoning

The overuse of fertilizers, particularly those high in nitrogen, has led to increased levels of nitrates in water supplies, with rural areas often bearing the brunt of the contamination. This has resulted in significant health risks and financial burdens for affected communities.

• Interference with oxygen uptake: Nitrates in the body can disrupt the normal transport of oxygen in the blood, leading to insufficient oxygen supply to vital organs and tissues.
• Skin discolouration: In cases of "blue-baby syndrome", infants may experience blue discolouration of the skin due to the reduced oxygen in their blood.
• Increased risk of cancer: Exposure to high levels of nitrates has been linked to an increased risk of bladder cancer, diabetes, and other health issues.
• Birth defects: Research has connected high birth defect rates with exposure to nitrate-contaminated water during pregnancy.
• Respiratory problems: Nitrate poisoning can cause respiratory issues, including nausea and difficulty breathing.
• Organ damage: Nitrates can interfere with the functioning of vital organs, such as the liver and kidneys.

Ocean acidification

Fertilizers can indeed cause water pollution. Excess fertilizers are polluting rivers, lakes, and bays, with the chemicals in fertilizers washing into waterways from hundreds of thousands of lawns. This can lead to eutrophication, where the overgrowth of aquatic vegetation clogs waterways, restricting access for fishing, boating, and swimming. As this vegetation dies, its decay uses up oxygen in the water, which can lead to fish kills. Certain harmful algal blooms can also release powerful toxins that kill fish and create dead zones.

Now, onto ocean acidification.

Nutrient pollution from fertilizers can accelerate the negative impacts of ocean acidification. A study by the University of Hawaii at Manoa found that nutrient pollution from human activities on land may exacerbate the effects of ocean acidification on coral reefs. Nutrient pollution was found to decrease overall reef growth and disrupt the natural chemical dynamics, making coral reefs more vulnerable to the stress of ocean acidification.

Eutrophication, caused by excess nutrients from agricultural fertilizer runoff, wastewater, and atmospheric deposition, is one of the indirect anthropogenic mechanisms contributing to ocean acidification. Eutrophication leads to increased heterotrophic respiration rates, which release CO2 and lower pH. This process has been observed in several regions, including the East China Sea, the Gulf of Mexico, and the Baltic Sea.

To address ocean acidification, local and regional decision-makers must understand the dynamics of eutrophication, upwelling, and changes in riverine runoff. Coordinated institutional frameworks and specific management actions are necessary to develop comprehensive management responses. Some suggested actions include setting up initiatives to assess the threat of ocean acidification, leveraging interstate coalitions, developing monitoring networks to map coastal areas' vulnerability, launching public education programs, and integrating ocean acidification into existing climate change programs.

In conclusion, fertilizers can cause water pollution, and nutrient pollution from fertilizers contributes to the problem of ocean acidification, particularly for coral reefs and other calcium carbonate-dependent organisms. Addressing this issue requires a combination of local, regional, and global efforts to reduce nutrient runoff and curb carbon dioxide emissions.

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