Zusammenfassung der Ressource
Eutrophication
- Nitrates are applied to fields as fertilisers.
- This allows plants to synthesise proteins
so they grow
- When it rains the nitrates run off the fields into lakes and rivers etc.
- This allows single celled algae to absorb the nitrates
- The algae hoard the ions through ACTIVE TRANSPORT
- This causes an ALGAL BLOOM. Where the population of algae
drastically increases and adds a layer to the top of a lake.
- Plants at bottom of water don't get any light and
die. Some algae also excrete toxins
- When algal cells die they float to bottom of water,
this is the perfect food source for bacteria
- When the bacteria break down the food source, they aerobically respire, and
they have a high BIOLOGICAL OXYGEN DEMAND (BOD)
- Fish and other organisms don't get enough oxygen so they die
- Bioaccumulation
- When the algae accumulate all of these nitrates, they only
have about 1ppm, but because they can't be broken down,
the concentration increases up the trophic levels
- The Nitrates, Heavy metals & Pesticides are stored in the fat and can't be
broken down
- When the herbivores eat the algae, they consume all of the Nitrates, and it can't
be broken down, so the concentration increases to 10ppm
- Then when the fish eat the herbivores: 100ppm
- And the dolphins: 500ppm
- This is enough to kill a dolphin, but as it is stored in the fat it wouldn't kill the dolphin until it didn't have a food
source and it is under stress, then the toxins in the blood would peak and kill the dolphin