Eutrophication in the Black Sea
The eutrophication taking place in the Black Sea makes us aware of the seriousness of this environmental problem. The incoming rivers of the Black Sea bring with them nutrients and pollutants in large amounts. The 1960s saw a sharp rise in eutrophication of this sea.
Eutrophication is described as a process through which natural as well as artificial substances, mainly phosphates and nitrates, are added to an aquatic ecosystem. The consequences or effects of addition of these nutrients to water bodies can be observed in different forms. Growth of phytoplankton in freshwater lakes and rivers is one of the effects of eutrophication. Cultural eutrophication is harmful in comparison to natural eutrophication because the former results from excessive deposition of nutrients in water bodies at a fast pace. This may occur in just a few decades. Natural eutrophication, on the other hand, takes place over centuries, at a slow pace. Cultural eutrophication is a global problem. Let us understand how cultural eutrophication takes place through the information presented below.
What is Cultural Eutrophication?
Generally, the nutrients responsible for eutrophication travel from one place to another by means of surface run off. However, in some cases, these nutrients may also leach to groundwater. The process of eutrophication which occurs at a fast pace, due to human interference, is called cultural eutrophication.
If eutrophication is severe, it may create hypoxic conditions in a water body. Hypoxia is characterized by low amount of oxygen dissolved in water bodies. Such a condition has harmful effects on the life of aquatic fauna, resulting in dead zones.
The different ways in which cultural eutrophication occurs are explained below.
he fertilizer run off into water bodies such as rivers and lakes is the prime source of cultural eutrophication. Nitrate and phosphate fertilizers are added to soil to nourish crops raised on farms. In the past few decades, use of such chemical fertilizers has increased manifold. Nitrates and phosphates are added to water bodies when residues of these fertilizers are drained off from fields.
The demand for chemical fertilizers to be used for agricultural purposes is expected to rise in the near future. Uncontrolled use of chemical fertilizers would worsen the situation further. Agriculturists should therefore, practice organic farming to reduce the harmful effects of cultural eutrophication.
Human Urban Wastewater Discharges
The sewage water released in water bodies from urban areas deposits into them nutrients like nitrates and phosphates. Such wastewater discharges are one of the important causes of rising eutrophication in water bodies. The concentration of nutrients in waste water discharges is generally quite high. Phosphorus compounds are also present in detergents used for washing clothes. Releasing them in water bodies further increases nutrient concentration. It is the cause of many related problems like clogging of waterways and uncontrolled growth of toxic algal blooms. Thus, apart from sewage water, detergents form an important source of phosphorus that is released in water bodies.
Industrial wastewater discharges account for 50% of phosphorus deposited in lakes and which originates in human settlements (Smith et al. 2006 published by the American Society of Limnology and Oceanography). The deposition of nutrients which leads to algal growth not only reduces the oxygen content in water, but also emits foul odor when these plants die and rot in water. Moreover, industrial discharges along with eutrophying compounds, contain harmful chemicals and pollutants.
Livestock breeding is one of the causes of occurrence of eutrophication in water bodies. The excrement of cattle and other livestock creatures contain nutrients such as nitrates and phosphates. These compounds get dissolved in surface water which gets washed off to nearby water bodies like lakes and rivers. This results into deposition of nutrients in the water bodies, which then causes growth of algae and other aquatic plants.
Disadvantages of Cultural Eutrophication
Cultural eutrophication causes many harmful effects on water bodies and nature in general. The rise in sedimentation in a water body (for e.g. a lake) shortens its life. The water present in water bodies loses its transparency. One of the effects of rise in sedimentation and excessive growth of aquatic plants like phytoplankton is increased turbidity of water.
Cultural eutrophication adversely affects the diversity of aquatic species. Due to development of hypoxic conditions aquatic organisms find it difficult to survive in eutrophic water bodies. Competition for survival is observed in organisms living in such water bodies. Loss of aesthetic value of water bodies also is one of the major effects of eutrophication.
Reducing the input of phosphorus into water bodies is an effective way of managing cultural eutrophication. Excessive growth of algae and other such aquatic plants pose a threat to the life of fish and other aquatic creatures. Cultural eutrophication, if not controlled in a timely manner, can disrupt the ecological balance of earth.