Eutrophication is a major environmental concern for rivers, coastal water, lakes, tributaries, and estuaries. The term refers to an increase in nutrients, especially phosphorus and nitrogen, resulting in an explosive increase of alga – the algal blooms.
Eutrophication can be categorized into two:
- Natural eutrophication
- Cultural eutrophication.
Natural eutrophication is the gradual buildup of nutrients, organic material, and sediments that takes place over centuries in many lake basins.
Cultural eutrophication, on the other hand, refers to an alteration of nutrient input in the water basins by human activities that lead to major ecological changes in water bodies over the decades.
The cultural process is primarily associated with phosphorus common in fertilizers and treated sewage. Phosphorus is the main actor as it is a strong stimulator of algae growth. The process is characterized by excessive plant and algal growth in the water bodies.
The concept of cultural eutrophication is particularly brought about by a human understanding that clear water with minimal visible organisms is better than organic-rich water.
The widespread modern use of phosphate in detergents and the presence of excess fertilizer in the runoffs has greatly contributed to an ecological challenge in the water bodies – generally termed cultural eutrophication.
In the natural process, the ecosystem continuously cycles the matter with the aid of plants and green algae to create a food base for herbivorous and carnivorous from the dissolved chemicals. Dead animals and plant materials are also decomposed by aerobic and anaerobic decomposers into simple forms that can be easily recycled into the natural cycles.
The water bodies are well-suited to deal with the matter of cycling, preserving the water quality. In cultural eutrophication, however, humans inject large amounts of artificial matter into the water’s ecological system, overwhelming the natural cycle, and thereby resulting in the water bodies changing from oligotrophic to eutrophic.
The oligotrophic water bodies have a rich supply of oxygen, unlike the algae-rich eutrophic water bodies. A good scenario of how human activities affect the ecology of water bodies is when humans dump sewage into water bodies. Dumping untreated sewage into a water body, for example, results in the fertilization of the algae, increasing their growth.
As the algae increases and dies, the aerobic decomposers also increase, resulting in a higher demand for oxygen in the water body. If the demand for oxygen is very high, it could outstrip the supply, making it difficult for fishes and aquatic organisms to survive in the water bodies.
In the absence of oxygen, the microorganisms capable of living in the absence of oxygen start to decompose organic substances, releasing harmful hydrogen sulfide and ammonia. This generally describes the concept of cultural eutrophication.
Various Causes of Cultural Eutrophication
Some of the common causes of human-induced eutrophication include:
The use of fertilizers is the leading cause of eutrophication. Using fertilizers, especially nitrate and phosphate fertilizers, on farms, lawns, and golf courses results in the accumulation of phosphate and nitrate in the nearby water body sources.
Once the nutrients get into lakes, oceans, rivers, and other water bodies, algae and plankton, among other aquatic plant life, become well-fed, resulting in an increase in their photosynthetic activity.
Increased photosynthesis causes a dense growth of algal blooms and other plant species. The excessive growth results in a reduced presence of oxygen in the water, thus triggering the eutrophication process.
2. Concentrated Animal Feeding Operations
Concentrated animal feeding operations are characterized by high discharge of artificial nutrients into rivers, lakes, and oceans. The nutrients accumulate in high concentrations, plaguing the water bodies with algal blooms and cyanobacteria.
3. Sewage and Industrial Discharge
Untreated sewage and industrial wastage, especially in major towns and developing countries, can get access to water bodies and stimulate the growth of algal blooms and other aquatic plants, threatening the survival of aquatic life in many ways.
Even treated water should not be discharged back into rivers or lakes as it can also cause an accumulation of excess nutrients in the water bodies.
The modern method of rearing fish and shellfish and growing aquatic plants without soil is also becoming a big contributor to cultural eutrophication.
If aquiculture is not properly managed, food particles and fish excretion can find their way into water bodies, creating a good environment for dense growth microscopic floating plants.
When humans cut trees, they increase the likeliness of eutrophication. Trees play an important role in holding the soil together. When trees are cut, soil erosion occurs, which carries the sediment and other nutrients into water bodies, creating a suitable environment for the explosive growth of algae blooms.
Effects of Cultural Eutrophication
Some of the common effects of eutrophication include but not limited to:
1. Deterioration of Water Quality
The most noticeable problem with eutrophication is the deterioration of water quality. Humans prefer clear water as opposed to nutrient-rich water.
In fact, the idea of using nutrient-rich water by some people sounds insane. If, for instance, a water source is affected, those dependent on nutrient-rich water would be unable to use the water until the quality improves.
Besides, the algal blooms are highly toxic. They even become more toxic in anaerobic conditions. Their presence in water bodies declines the availability of clean drinking water.
What is even more, the dense growth of algal blooms and other plants can block water supply systems, limiting piped water availability.
2. Threatens Survival of Aquatic Life
A common characteristic of eutrophication is the explosive growth of phytoplankton and other plants. The explosive growth of plants increases the demand for oxygen, resulting in a reduced availability of dissolved oxygen for respiration by other aquatic plants and animals in the water.
Also, as algae plants die and decompose, the oxygen continues to deplete, resulting in the suffocation of fish and other aquatic life forms. When water can no longer hold oxygen, the condition encourages the growth of bacteria that produce toxins that are fatal to marine mammals and birds.
Eutrophication encourages the growth of cyanobacteria, a bacteria that generates a red tide that releases very powerful toxins with high poison levels into the water. The toxins can be fatal even at very low concentrations. The anaerobic conditions created by eutrophication also encourage the growth of toxic compounds in the water body.
The poison can cause death to humans and animals if ingested at the least concentration in drinking water. The toxic compounds can also go up the food chain through bio-accumulation and bio-magnification, causing other health complications like cancers.
For example, eutrophication is highly associated with the poisoning of shellfish. Shellfish accumulate poison in their muscles resulting in human poisoning. High nitrogen concentration in drinking water can also inhibit blood circulation in infants.
4. Inhibit Fishing
Eutrophication increases the growth of algae and minute plants as well as photosynthetic bacteria. The explosive growth of the algae and plants can lead to the development of extensive and dense mats of floating plants that make it difficult to set fishing nets in the water. They can also limit the mobility of boats and other fishing vessels.
5. Degradation of Recreational Opportunities
If algal blooms and other plants affect an extensive area, they reduce the transparency and navigation in the water, lessening the recreational values and opportunities of the water bodies. The growth, especially on the surface, will negatively affect activities such as boating and swimming.
Solutions to Cultural Eutrophication
Some of the solutions to cultural eutrophication include the following:
1. Managing Water Pollution
Since pollution is a leading cause of eutrophication, reducing it in various forms can help prevent further destruction of water bodies. Cutting back on nitrogen and phosphates discharged into water systems can help lower the nutrient content in the water system, and hence control eutrophication.
However, for this solution to work, industries, and municipalities, as well as individuals, should work together in reducing their pollution levels. If industries cut back on their pollution and municipalities continue to pollute water systems, the gains will be very few.
Eutrophication occurs as a result of nitrate and phosphate use. To minimize the presence of phosphate and nitrate in the water bodies, people should substitute nitrate and phosphate fertilizers with compost manure. Compost manure does not contain high elements of nitrates and phosphates that cause eutrophication.
Furthermore, all essential elements of compost manure are broken down and synthesized by plants avoiding the eutrophication cycle.
3. Create and Strengthen Non-Point Pollution Laws
Governments should create laws and policies against non-point pollution. EPA points out that non-point pollution causes the biggest challenge in eutrophication control.
Controlling nutrient sources can greatly reduce eutrophication, and hence, governments and municipalities across the world should develop stringent measures to discourage on-point pollution.
Minimizing non-point pollution works by lessening the number of nutrients that enter aquatic systems. The policies should aim at enhancing high water quality standards while discouraging pollution.
4. Ultrasonic Irradiation
Over the last few years, tech developers and scientists have been working towards creating technologies that can help reduce pollution and even reverse the damages already caused.
Ultrasonic irradiation, as an example, is one such technology that has tremendously helped in controlling eutrophication by causing cavitations that produce free radicals that destroy algae cells.
Other technologies that convert plant growth present in water bodies into energy have also been advanced. Although innovations are still expensive, they should be advanced towards reversing years of human pollution that cause cultural eutrophication.
Governments are, therefore, called upon to as well invest in supporting and encouraging new innovations that deal with environmental challenges.