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Post on 19-May-2015
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Aims of the session:
• Learn about fertilisers and their effects on the environment.• Be able to answer exam questions on the effects.• Learn about Pesticides and their effects• Summarise the key points about pesticides
Fertilisers and Pesticides
Fertilisers
Th
e p
rocess o
fEu
trop
hic
ati
on
fertiliserssewage
(liquid domesticand industrial waste)
mineralsesp. nitrates
mineralsesp. phosphates
eutrophication
algal bloom
competitionfor light
consumers can't consume fast enough
dead plants dead algae
The process of Eutrophication cont.
dead plants dead algae
detritus
more decomposers
use up oxygenby aerobic respiration
(increased BOD)
aerobes die(invertebrates,
fish, etc)
anaerobic bacteriathrive. ReleaseNH4, CH4, HS2
Biochemical Oxygen Demand (BOD).
This measures the rate of oxygen consumption by a sample of water, and therefore gives a good indication of eutrophication. A high BOD means lots of organic material and aerobic microbes, i.e. eutrophication
The nitrate concentration falls during spring and summer and rises during autumn and winter
Less algal growth as autumn beginsPossibly all plants have died
Pesticides
Pesticides
Include:
• Herbicides• Insecticides• Fungicides• Bactericides
Pesticides
Persistence + Lipid solubility
= Bioaccumulation
Bioaccumulation
waterzooplankton
0.04 ppmsm all fish0.5 ppm
large fish2 ppm
birds25 ppm
E.g DDT
http://www.abdn.ac.uk/~nhi904/biocet/index.htm
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