Biodiesel production from vegetable oil through transesterification process

Chemicals in our Environment

BY-GAUTAM PARMARS.Y, B.Sc (B.T)

Preface >What is Biomagnification &

bioaccumulation ?

>Chemical Pollutants -DDT, PCB’S Mercury..

>Effects of Pollutants -Organisms, environment,

>Characteristics of pollutants

>Bioremediation -Using plants, microbes

Bioaccumulation is the “build-up of chemicals in living organisms”.

The chemical accumulates because it does not break down easily (decomposers can’t break them

down)The chemicals get stored in fat-cells of organisms

and can cause serious problems...

Biomagnification is the process where chemicals accumulate AND become more concentrated at each trophic level of the food chain.

-Water-Phytoplankton

-Zooplankton-Small fish-Large fish

-Top Predator: Human, osprey, eagle, otter – highest amount of

toxic chemical

Ex. Biomagnification

Chemical PollutantsHumans have been introducing synthetic (man-made) chemicals into the

environment.Some examples are: PCBs (polychlorinated

biphenyls) widely used in paints, plastics,

lubricants up to 1977

DDT (an insecticide for mosquitos) now banned

in many countries

DDTDDT was first used in WWIIto protect against diseases

such as typhus and malaria.

It is cheap and effective as an insecticide – so it began to be manufactured for home

use.

Before it was banned in 1972 by the EPA for use in

agriculture, 1,350,000,000 pounds of DDT had been made in North America.

Overused on crops as a pesticide

Inventor received Noble Prize

*DDT is used today in such African nations as Zimbabwe and Ethiopia to control mosquitoes and the tsetse fly.

*These two insects cause serious diseases, such as malaria and

sleeping sickness. Used as an InsecticideIn the beginning, most pests were sensitive to DDT but a few were

resistant

The resistant forms survived and reproduced

In the end, most pests were resistant to DDT

EFFECTS OF DDT*DDT is found to have

estrogenic effects: >Causes reproductive

disorders

>Weakens the shells of eggs (eggs break or do not hatch)

>Can also cause nervous system/ immune system

disorders in animals

Was banned in 1972 after the Bald Eagle population had a

noticeable crash.

Eggshell thinningDDT interferes with metabolism of calciumResult - thin shells in predator birds such as

osprey, bald eagles, brown pelicansBirds unable to brood (aka sit on) their eggs

without breaking them

PCBsUsed widely in products like paints,

plastics, etc as softening agents from the 1930’s – 1970’s

Banned in North America in 1977

PCBs interfere with immune function making an organism more susceptible

to disease (ex: cancer)

• Both DDT and PCBs are called “persistent organic pollutants”

(POPs)• This is because they take a LONG

time to break down

HALF-LIFE = the time it takes for ½ the substance to break down

Mercury>Source: Emissions from coal-burning power plants, metal processing, medical and other waste>Made bioavailable by bacteria

>Inorganic mercury → Organic form of mercury that is biologically active

Elementary Mercury (Hg)…..Methylmercury (CH3Hg) – most toxic form>Form ingested by consuming fish>Concentrated in muscle tissue

>More in older fish than younger fish >changed from Hg to this form by bacteria

Characteristics of pollutants:

In order for biomagnification to happen, substance must be:>Long lived

>Soluble in fat>Mobile

>Biologically activePutting it into perspective:

>Only some substances biomagnifies

>Most substances are water soluble and are excreted into the water>Many breakdown quickly

>Many are not biologically active

Why does this happen??? Chemicals are taken up faster than they are used.

Chemicals can’t be broken down by the organism for use.

Chemical pollutants that are bioaccumulated come from many sources

PesticidesIndustrial Smoke StacksAutomobile Emissions

Deliberate Discharge of Compounds into Water

BIOREMEDIATION Undoing the Damage

Science has found ways of reducing the effects of chemical pollution on the environment...

Using living organisms (plants, bacteria) to naturally cleanup chemical pollutants through biodegradation

Chemical-eating bacteria and micro-organisms can break down chemicals into non-toxic compounds

Plants can also be used to help trap hazardous wastes such as heavy metalsThe plants uptake the metals and trap them in their tissues

Plants also help stabilize by reducing wind and water erosion (that would spread contaminants).

Bioremediation With Plants

Recently, scientists were able to change a gene in these chemical-eating bacteria allowing them to fluoresce (glow) when they are in contact with oil or other chemical pollutants!

THANX A

LOT..!!!CHECKPOINT….!!