What is marine eutrophication 10

Eutrophication is a phenomenon of water pollution caused by excessive content of plant nutrients such as nitrogen and phosphorus.

Due to human activities, after a large amount of industrial wastewater and domestic sewage and plant nutrients in farmland runoff are discharged into slow flowing water bodies such as lakes, reservoirs, estuaries, bays, etc., aquatic organisms, especially algae, will multiply in large quantities, changing the number of biomass species and destroying the ecological balance of water bodies. A large number of dead aquatic organisms are deposited at the bottom of the lake, decomposed by microorganisms, and consume a large amount of dissolved oxygen, which reduces the dissolved oxygen content of the water body sharply, deteriorates the water quality, and affects the survival of fish, which greatly accelerates the eutrophication process of the water body. When eutrophication occurs in the water body, the water body often appears blue, red, brown, milky white and so on due to the mass proliferation of plankton.

In the seawater, it is called red tide. In the waters where red tides occur, some plankton multiply explosively, turning the water red, hence the name "red tide". These algae have a foul smell, are poisonous, and cannot be eaten by fish.

Algae shade the sun, so that the underwater plants are hindered by photosynthesis and die, and after decay, they release nitrogen, phosphorus and other plant nutrients for algae use. Over the years, this creates a vicious cycle of algae blooms, deterioration of water quality and fishy odors, resulting in fish deaths.

Marine eutrophication refers to the fact that human beings will use a large amount of nitrogen, phosphorus, and iron (in fact, nitrogen and iron play a major role, because there is no shortage of phosphorus in seawater, and the content of nitrogen and iron becomes the determining factor of eutrophication). But the determinant of eutrophication in water is phosphorus. Therefore, as in Japan, the requirements for phosphorus in various effluents are very strict.

Kunming is a phosphorus-free city. ) and other wastewater discharged into the ocean, so that the water body nitrogen, phosphorus, iron exceeds the standard. It causes algae blooms, mainly diatoms (mostly reddish-brown), so it is called red tide.

Some of these algae can produce toxins that kill fish from poisoning. Some do not produce toxins, but they remain in the gills of the fish, so that the gills cannot be properly exchanged with the oxygen in the water, resulting in a lack of oxygen in the fish, and eventually suffocation.

Nutrients (e.g., nitrogen, phosphorus) in seawater are necessary for the growth, development, and reproduction stages of phytoplankton. However, if nutrients are input in excess, they can accumulate in the water body, causing eutrophication. Eutrophication of water bodies provides a material basis for the proliferation of red tide organisms and the formation of red tides, so in order to prevent the occurrence of red tide disasters, it is necessary to effectively control the eutrophication of sea areas.

The substances that cause eutrophication of water bodies are mainly used in the discharge of industrial and agricultural wastewater, marine aquaculture wastewater and domestic sewage. Their impact is particularly pronounced in shallow coastal waters, estuarine areas, and closed or semi-enclosed bays.

Controlling eutrophication in the sea area should be carried out at all stages of the discharge of industrial and agricultural wastewater, before the nutrients enter the sea. At present, China's wastewater treatment rate is still low, and a considerable part of the wastewater is directly discharged without taking any treatment measures. This wastewater has a negative impact on the surrounding environment and provides material conditions for eutrophication of water bodies.

Second, it is necessary to rationally develop the marine aquaculture industry. In some coastal areas, the one-sided pursuit of high yield, high efficiency, increase the breeding density, the implementation of more bait, more output of the unreasonable breeding mode, so that the remaining bait in the aquaculture water body greatly increased. A large amount of nutrients contained in the bait dissolve in the water and are discharged into the seawater in the form of aquaculture wastewater.

In addition, the excrement of farmed fish, shrimp and shellfish contains a large number of dissolved nutrients, such as ammonia, urea, etc., which are also discharged into the surrounding water bodies in the form of aquaculture wastewater, which is easy to cause.

Marine eutrophication is the material basis and primary condition for the occurrence of red tides.

Due to the large amount of urban industrial wastewater and domestic sewage discharged into the sea, the nutrients are sub-collected in the water body, resulting in eutrophication of the sea area. At this time, nutrients such as nitrogen and phosphorus in the waters; The content of trace elements such as iron and manganese, as well as organic compounds, has greatly increased, promoting the proliferation of red tide organisms.

Eutrophication means that there are a lot of nutrients, and if there are more nutrients, what red algae and green algae will grow.

If there are too many of them, they will consume too much oxygen in the water, so generally if there is any tide, the fish will die...

Refers to excessive elements such as nitrogen, phosphorus, and potassium.

Causing the overflow of algae in the seawater.

It's just that there are too many p n in the sea to cause bad consequences.

n p k exceeds the standard

High concentration meets fertilizer exceedance?

Offshore eutrophication manifests as red tide.

Offshore eutrophication is the phenomenon of "fertilization" of coastal waters, and the main reason for this is the excessive amount of nitrogen and phosphorus nutrients in offshore ecosystems, resulting in additional phytoplankton growth and disturbing the normal community structure and water quality composition of offshore ecosystems. In most offshore ecosystems, excessive input of nitrogenous nutrients is a major cause of offshore eutrophication.

Most of these excess nutrients come from human activities, such as agricultural and industrial activities. The nitrogen formed by these anthropogenic activities is mainly used in chemical fertilizers, fossil fuel combustion, manure, ammonia emitted by the lead industry, sewage, and aquaculture, especially chemical fertilizers, which contribute the most nitrogen, accounting for more than 70% of the human-formed nitrogen.

The most significant consequence of offshore eutrophication is the emergence of anoxic or even anaerobic zones or the expansion of existing anoxic and anaerobic zones. Hypoxia here refers to the content of dissolved oxygen in the water body less than or equal to two milligrams per liter, the reason for this consequence is that the hand is good because the excessive nutrient input in the surface water body stimulates the growth of phytoplankton, and then generates a large amount of organic matter to settle to the bottom and remineralize, that is, the process of organic matter being degraded into inorganic matter.

This process consumes oxygen, which reduces the concentration of dissolved oxygen in the bottom water, creating a bridge between anoxic or even anaerobic zones. Oxygen-rich habitats are reduced due to the formation or expansion of anoxic zones, which can threaten or even impair the survival of aerobic organisms, and ultimately lead to the reduction of offshore biodiversity and ecosystem function. Eutrophication can also lead to algal bloom outbreaks, i.e. algae blooms.

Marine eutrophication is not just caused by soil erosion, but also by a number of other causes. For example, the sewage discharged in our lives and industrial production, despite its black, dirty and smelly, is rich in a variety of nutrients, not only nitrogen, but also phosphorus and potassium, which can be described as nitrogen, phosphorus and potassium. Like the laundry detergents we use a lot, the vast majority of them have phosphorus content.

According to figures provided by the State Environmental Protection Administration, about 37 billion tons of sewage are discharged in China every year, of which about 80% is discharged without any treatment. Increasing soil erosion and such a huge amount of sewage discharge can be imagined that many nutrients such as nitrogen and phosphorus will enter the lakes and oceans. After the appearance of red tide, countless marine microscopic organisms rush to float on the surface of the water, which is impermeable, thus hindering the transmission of oxygen from the atmosphere to the water, reducing the dissolved oxygen in the water, and suffocating and dying of fish, shrimp and shellfish due to lack of oxygen.

Without the abominable dinoflagellates in the lake, there would be no red tide, but the consequences of eutrophication in the lake are also very severe, the bottom of the lake is overgrown with weeds, the water surface is full of duckweeds, and the aquatic resources and tourism resources will be greatly reduced, or even completely lost.

(1) Attention should be paid to the treatment of urban sewage and industrial sewage to improve the sewage purification rate.

2) Rational development of marine aquaculture. In order to alleviate the problem of eutrophication of water bodies caused by mariculture, the following measures should be taken:

According to the environmental conditions of the waters, select some aquaculture species that have a purification effect on water quality, and reasonably determine the breeding density and control the breeding area.

Carry out multi-species polyculture, rotational culture, three-dimensional culture, especially fish, shrimp, shellfish and algae polyculture, and establish an ecological breeding system.

Improve the breeding technology, improve the bait composition and feeding technology, so that it is conducive to the feeding of aquaculture organisms, reduce residual bait, and reduce the pollution of water quality and substrate.

Sewage and waste from pond farming cannot be discharged directly into the seawater, and should be treated by means of gradual filtration.