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Dieren en planten

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Nutrients   Phosphoric compounds   

Phosphoric compounds

Phosphate is a compound made from phosphor and oxygen. Phosphoric compounds are nutrients, just like nitrogen compounds. Phosphor is of vital interest for all organisms because it is a building material for various proteins and the skeleton structure. Seawater contains a natural concentration of phosphor. In addition, a large amount of extra phosphor used to enter the environment from impure sewage and the livestock industry. An excess supply of phosphoric compoundsleads to eutrophication in seawater. The graph above shows that pollution from phosphoric compounds has declined since the 1980s.

  • Phosphates in the food chain

    In the marine environment, the algae in particular absorb phosphates in the water, introducing phosphorus compounds into the food chains. When plant or animal material decomposes, the phosphorus compounds are released again. The assumption 'more phosphates - more phytoplankton - more zooplankton - more small fish - more large fish' is not always true because plankton species often develop that are not consumed by the animals further up in the food chain.
    One can see in the graph that the phosphoric level in the middle of the North Sea measures around 0.02 mg per liter. Dutch water policy considers this as a natural concentration. It is clear that the phosphoric level in coastal waters is still not back at this natural level. The declining trend between 1980 and 1995 is mostly due to improvement in the sewage systems and regulations for the manure problem. No further decline is taking place.

  • Phosphate concentrations

    Phosphor is declining in river water. A 50% decline in the emissions into the North Sea in 1995 with respect to 1985 was achieved. Detergents no longer contain phosphates. The industry and the water purification installations also discharge fewer phosphates than several years ago. The industry has discharged 74% fewer phosphate compounds than in 1985. The emission of phosphate from farming declined withing ten years to five million kilograms per year in 1994. Production of phosphate in the livestock sectore has also declined; from 220 million kilograms in 1990 to 193 million kilograms in 1998. The effect of the decline in phosphate discharges could be seen in 2005 particularly by the small amount of foam on the beach, which is caused by the decomposition of the foam algae Phaeocystis.
    The consequences of the high phosphate concentrations in coastal water, the policy directed at declining emissions and the consequences of the presently declining emissions are found in the chapter on eutrophication.