Eutrophication is reported to be widespread in Europe's seas and fresh water; this affects fish stocks as well as human health and recreational use. The main source of nitrate is generally diffuse pollution from agriculture. Since the s the concentration of organic pollution has been generally reduced and the oxygen concentration increased, especially in the previously most impacted rivers.
Rising nitrogen loads combined with phosphorous have led to exuberant and unwanted plant and algal growth in many freshwater habitats and coastal areas throughout the world. In the United States, eutrophication - rapid plant growth in water resulting in oxygen deprivation for other species - accounts for about half of the impaired lake area and 60 per cent of the impaired river reaches Carpenter and others It is currently published as a searchable online platform with profiles of world problems, action strategies, and human values that are interlinked in novel and innovative ways.
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Here's an overview in one minute. Eutrophication is a big word that describes a big problem in the nation's estuaries. Harmful algal blooms , dead zones , and fish kills are the results of a process called eutrophication — which occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth to estuaries and coastal waters.
Sixty-five percent of the estuaries and coastal waters in the contiguous U. Excessive nutrients lead to algal blooms and low-oxygen hypoxic waters that can kill fish and seagrass and reduce essential fish habitats. Many of these estuaries also support bivalve mollusk populations e. Eutrophication sets off a chain reaction in the ecosystem, starting with an overabundance of algae and plants. The excess algae and plant matter eventually decompose, producing large amounts of carbon dioxide.
Harmful algal blooms HAB are bloom events involving toxic or harmful phytoplankton. These cause harm through the production of toxins or by their accumulated biomass, which can effect co-occurring organisms and alter food web dynamics. Impacts include:. For more details on toxic algal blooms, see the article Harmful algal bloom. Phytoplankton are the food source for numerous other organisms, especially the zooplankton.
Zooplankton are heterotrophic plankton. They are primarily transported by ambient water currents but many can swim. Through their consumption and processing of phytoplankton and other food sources they play a role in aquatic food webs as a resource for higher trophic levels including fish. Zooplankton can be divided in two important groups: crustacean copepods and krill and gelatinous zooplankton. The most well-known are the jellyfish. There is some evidence that gelatinous zooplankton organisms increase in relative importance versus crustacean zooplankton in areas where the natural species diversity has been affected by pollution, over-fishing and climate change [2].
The growth of phytoplankton causes increased turbidity or decreased penetration of light into the lower depths of the water column. In lakes and rivers this can inhibit growth of submerged aquatic plants and affect species which are dependent on them fish, shellfish.
Oxygen is required for all life forms on the planet. Oxygen is produced by plants during photosynthesis. At night animals and plants, as well as aerobic micro-organisms respire and so consume oxygen which results in a decrease in dissolved oxygen levels. Algal blooms may cause strong fluctuations in dissolved oxygen levels. When the algae population is growing at a fast rate, it may block sunlight from reaching other organisms and cause a decrease of dissolved oxygen levels.
When algae die, they are decomposed by bacteria which in this process consume oxygen so that the water can become temporarily hypoxic. Oxygen depletion, or hypoxia , is a common consequence of eutrophication, both in fresh water and seawater.
The direct effects of hypoxia include fish kills , especially the death of fish that need high levels of dissolved oxygen Fig. There is some evidence that hypoxic conditions promote the growth of cyanobacteria as a consequence of enhanced phosphorus release [3]. Many cyanobacteria species produce toxins that are lethal to birds and animals. The respiration of bacteria that decompose dead algae not only causes hypoxia due to oxygen consumption, but also produces CO 2 and thus causes an increase in the carbonic acid content of the water.
A sharp increase in acidity pH even below 7 has been observed in highly eutrophic estuaries and lagoons along the east coast of the US, coinciding with hypoxia [4]. Acidification is an annual feature of these estuaries during summer when algae decay and oxygen depletes. Nuclear waste can have detrimental effects on marine habitats. Nuclear waste comes from a number of sources: Operations conducted by nuclear power Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment.
Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans. Pollutants from industrial Dumping of litter in the sea can cause huge problems. Litter items such as 6-pack ring packaging can get caught in marine animals and may result in death. Different items take different lengths of time to degrade in water: Cardboard — Takes 2 weeks to degrade Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers.
Sewage is the term used for wastewater that often contains faeces, urine and laundry waste. There are billions of people on Earth,
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