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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