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