G.RAJITHAMAM/2014-02

Ozone is a naturally-occurring gas.

IS IT GOOD (OR) BAD ?????

Troposphere- “BAD” ozone is an air pollutant that is a key ingredient of urban smog.

Stratosphere-“GOOD” ozone protects life on Earth by absorbing some of the sun’s UV rays.

WHAT IS OZONE ???

HOW OZONE LAYER FORMS ????

The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson.

USE OF OZONE LAYER

Ozone depletion refers to the thinning of the ozone layer, which allows more UV-B radiation to reach the Earth’s surface.

Ozone depletion occurs when destruction of the stratospheric ozone is more than the production of the molecule.

The ozone hole is defined geographically as the area where in total ozone amount is <220 Dobson units.

WHAT IS OZONE LAYER DEPLETION

CAUSES FOR OZONE LAYER DEPLETION

Natural causes : Sun-spots

Stratospheric winds

Man-made causes (ODS): Chlorofluorocarbons (80%) Methyl Chloroform Hydrochlorofluorocarbons Carbon Tetrachloride etc...

HOW OZONE LAYER DEPLETES ???

WHAT HAPPENS IF OZONE LAYER DEPLETES ???

Skin cancer: Basal And Squamous Cell Carcinomas Malignant Melanoma

Eye damage: Photokeratitis (snow blindness), Cataracts.

Immune system damage

Accelerated aging of skin

Other effects: Ozone chemicals can cause difficulty in

breathing, chest pain, throat irritation, and hamper lung functioning.

EFFECT ON HUMANS

SKIN CANCER

Basal And Squamous Cell Carcinomas

MALIGNANT MELANOMA

Symptoms : Pain Intense tears  Eye lid twitching Discomfort from bright light  Temporary loss of vision

Treatment:NSAID-Non steroidal anti inflammatory

drug-eye drops

PHOTOKERATITIS (Snow blindness)

Symptoms :Vision that is cloudy, blurry, foggy.

Problems driving at night such as glare from oncoming headlights.

Double vision.

Sudden changes in glasses prescription.

Treatment:Surgery is most common

CATARACTS

Suppress immune system.

Accelerate aging of skin due high exposure.

Cause an outbreak of rash in fair skinned people due to photo allergy.

Over Exposure to UV-B rays leads to:

Sunscreen use can help prevent two types of skin cancer. Protect the skin against the solar radiation using skin creams with SPF.

The greater the numerical value of the SPF the greater the protection.

Use lip balm with SPF.

SKIN PROTECTION

EYE PROTECTION

 Sunglasses or eye protection that transmits 5–10% of visible light and absorbs almost all UV rays.

Additionally, these glasses should have large lenses and side shields to avoid incidental light exposure.

Sunglasses should always be worn, even when the sky is overcast, as UV rays can pass through clouds.

EFFECT ON CROPSGrowth and development :The physiological and developmental processes of plants will be affected by UV-B radiation.Symptoms include bronzing and glazing of leaf surfaces. Exposure to UV-B decreased plant height, leaf area. Broad leaved crops are more susceptible to UV rays when compare to narrow leaved crops.Cell physiology:UV-B radiation causes a net inhibition of photosynthesis in a wide range of plants. Stomatal function, and thus leaf gas exchange, is also commonly impaired.

Sensitive to UV-B Insensitive to UV-B

Soya bean Lucerne

Clover Cabbage

Pea Lettuce

Bean Cotton

Cauliflower Rice

Turnip Wheat

Spinach Maize

Cucumber Tomato

Mono cotyledons are less sensitive to

UV-B radiation than Di cotyledons.

UV RADIATION AND PLANTSReproduction:UV-B radiation can alter both the time of flowering as well as the number of flowers in certain species. Although pollen appears resilient to UV-B radiation damage, owing to high levels of flavonoids in the anthers and pollen wall, germinating pollen tubes are highly sensitive to UV radiation. Others:The changes in plants morphology induced by UV-B may affect competition for light.DNA absorbs UV-B radiation and forms dimers means that enzymes cannot “read” the DNA code, results in mutated cells or transcriptions losses.

Water deficit in combination with elevated UV-B irradiation did not reduce yield to a greater extent than water deficit alone. Water stress may therefore mask UV-B responses of plants.

Elevated CO2 levels may also modify the response of sensitive plants to UV-B irradiation. In rice and wheat (but not in soybean) an increase in seed yield and biomass under elevated CO2 was reversed under moderate levels of supplementary UV-B irradiation.

UV - B RADIATION AND ENVIRONMENTAL INTERACTIONS

CAN PLANTS PROTECT THEMSELVES AGAINST INCREASED UV-B?

Increased thickness of leaves reducing the proportion of inner tissues exposed to UV-B radiation.

When exposed to increasing amounts of UV-B, many species of plants can increase the UV-absorbing pigments

( Flavonoids ) in their tissues.

Have repair mechanisms in plants includes repair systems for DNA damage.

Montreal Protocol : (adopted in

1987) Panel of experts was formed to

investigate substances responsible for hole formation.

Established policies that prevent future use of certain types of chemicals.

Stipulated that the production and consumption of compounds contributing towards depletion of ozone in the stratosphere were to be phased out.

WHAT IS BEING DONE TO COUNTER THE EFFECTS OF OZONE DEPLETION ???

SIGNS OF RECOVERY ???

There have been some signs of recovery 1997 satellite

showed a decline of several known ozone-depleting gases.

Satellite images show some slowing down of ozone loss.

However….RECOVERY IS SLOW

EFFORTS NEED TO BE CONTINUED

Create reliable modelsTo gain a better understanding of the effects ozone

depletion has on organisms living within different ecosystems.

Enforcement of Montreal ProtocolTo reduce concentrations of chemicals responsible

for ozone depletion.

Monitoring chemicals being emitted

Gain a better overall understanding on just how ozone depletion is affecting our planet

THANK YOU