Talk Fourteen:

Impacts on the Biosphere

Chapter 25

Human Biology (BIOL 104)

• The atmosphere sustains life and is sustained by life.

• The Gaia hypothesis– The entire planet is a

living breathing organism and will protect itself – homeostasis of the whole planet!!!

• The biosphere works in “cycles”

• Nitrogen• Carbon• Water

The Biosphere

So, what’s up with the biosphere?• POLLUTION!!!!!!!!!!!!!!!

• This is any substance that is present in the wrong quantities or concentration, in the wrong place, at the wrong time.

• Toxic dumps and oil spills are the main two forms of pollutants that damage the biosphere.

Figure 19.6Acid Rain• Occurs when sulphur dioxide and nitrogen oxides are emitted into the atmosphere, undergo chemical transformations and are absorbed by water droplets in clouds.

• The droplets then fall to earth as rain, snow, mist, dry dust, hail, or sleet.

• This can increase the acidity of the soil, and affect the chemical balance of lakes and streams

Acid Rain• Wet deposition• Occurs when any form of

precipitation (rain, snow, etc) removes acids from the atmosphere and delivers it to the Earth's surface.

• This can result from the deposition of acids produced in the raindrops or by the precipitation removing the acids either in clouds or below clouds.

• Wet removal of both gases and aerosol are both of importance for wet deposition.

Acid Rain• Dry deposition• Acid deposition also occurs via

dry deposition in the absence of precipitation.

• This can be responsible for as much as 20 to 60% of total acid deposition.

• This occurs when particles and gases stick to the ground, plants or other surfaces

Surface Waters and Aquatic Animals

• Both the lower pH and higher aluminium concentrations in surface water that occur as a result of acid rain can cause damage to fish and other aquatic animals.

• At pHs lower than 5 most fish eggs will not hatch and lower pHs can kill adult fish.– As lakes become more

acidic biodiversity is reduced.

• Acid rain has eliminated insect life and some fish species, including the brook trout in some Appalachian streams and creeks.

Not all fish, shellfish, or the insects that they eat can tolerate the same amount of acid; for example, frogs can tolerate water that is more acidic (i.e., has a lower pH) than trout.

Surface Waters and Aquatic Animals

Figure 19.8Ozone depletion•Used to describe two distinct but related observations: •A slow, steady decline of about 3 percent per decade in the total amount of ozone in Earth's stratosphere during the past twenty years

•A much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole.

Figure 19.8Ozone depletion

•Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms.

•The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface.

•Here it filters out the shorter wavelengths (less than 320 nm) of ultraviolet light (270 to 400 nm) from the Sun that would be harmful to most forms of life in large doses.

Figure 19.8Ozone depletion•These same wavelengths are also responsible for the production of vitamin D, which is essential for human health.

• Since 1955, the ozone levels have steady declined each year.

•Main reason for this depletion:•Chlorofluorocarbons (CFCs)•Used as nontoxic refrigerants •Expellant in aerosols

•In 1987, 43 nations met to cut back on the use of these compounds.

Figure 19.8Ozone depletion

•When ultraviolet light waves (UV) strike CFC (CFCl3) molecules in the upper atmosphere, a carbon-chlorine bond breaks, producing a chlorine (Cl) atom.

•The chlorine atom then reacts with an ozone (O3) molecule breaking it apart and so destroying the ozone.

Provided for use by the National Oceanic and Atmospheric Administration (NOAA)

Figure 19.8Ozone depletion

•This forms an ordinary oxygen molecule(O2) and a chlorine monoxide (ClO) molecule. •Then a free oxygen atom breaks up the chlorine monoxide. The chlorine is free to repeat the process of destroying more ozone molecules.

•A single CFC molecule can destroy 100,000 ozone molecules. Provided for use by the National Oceanic

and Atmospheric Administration (NOAA)

Figure 19.8Ozone depletion•Effects on Humans:

UVB (the higher energy UV radiation absorbed by ozone) is generally accepted to be a contributory factor to skin cancer.

In addition, increased surface UV leads to increased tropospheric ozone, which is a health risk to humans.

Effects on Crops:An increase of UV radiation

would also affect crop. A number of economically important species of plants, such as rice, depend on cyanobacteria residing on their roots for the retention of nitrogen. Cyanobacteria are very sensitive to UV light and they would be affected by its increase.

Figure 19.9CO2 and Global Warming•The greenhouse effect:

• The process in which the absorption of infrared radiation by an atmosphere warms a planet. •Without these greenhouse gases, the Earth's surface would be up to 30° C cooler.

•CO2 is used in photosynthesis to make carbohydrates.

CO2 levels rise at night and fall during the day naturally.

Due to the photosynthetic activity of plants

•CO2 is released during respiration or when organic compounds are burned.

Figure 19.9CO2 and Global Warming•An increase of CO2 decreases the amount of heat which can escape through the atmosphere.

•Thus the temperature of the Earth increases.

•This has many effects.•Warmer Ocean layers.•Atmospheric shifts.•Warmer surface temperatures

•2011 was hottest year on record.

Figure 19.9CO2 and Global Warming•First detected in 1896

•Causes droughts in semi-arid grassland areas.

•Increase in number and severity of forest fires.

•Partial melting of the polar ice caps.

•Will lead to increase in sea level.

•Pathogens that exist in warm climates will become more widespread.

Figure 19.9CO2 and Global Warming

•As climates shift, many existing species of plants and animals will become extinct.

•Biodiversity would suffer a decline of uncertain scope.

•Following the start of the industrial revolution CO2 content has increased 25%.

•Global temperatures and CO2 levels rise and fall together

Fracking• According to the U.S.

Energy Information Administration:– In 2000, the USA had

342,000 natural gas wells.

– By 2010, more than 510,000 were in place — a 49% jump!

• Twenty states have shale gas wells– they tap rock layers that

harbor the gas in shale formations  Taken from USA Today

29th May 2012

Fracking• Drill down to gas layer

– Pump in sand/water/chemicals

• Mixture cracks shale rock and fills in with sand– Allows gas to move

up well hole

• Gas collected.

• Water recover for reuse or sent to treatment plant.

Fracking

Used with permission from Fracfocus.com

• The most commonly used in the USA:-

• Methanol• Cellulose• Boric acid• zirconium, chromium, antim

ony, and titanium salts– The first three are known

carcinogens!

• Blowout – gas can explode out the wellhead, injuring people and spewing pollutants.

• Gas leak – Methane could travel into the water table.

• Air pollution – When methane is released without being burned, it acts as a potent

greenhouse gas, trapping 20 times as much heat as carbon dioxide.

• Wastewater overflow – If stored in open pits that emit noxious fumes and can overflow with rain.

• Other leaks  – spills or illicit dumping.

• Home explosions – If methane does get into the water table — because of cracked cement, local

geology or the effects of old wells — it can build up in homes and lead to explosions.

Potential hazards due to Fracking

Then why Frack in the first place?

• Good• According to the  National

Petroleum Council:– Without it, we would lose

45 percent of domestic natural gas production and 17 percent of our oil production within 5 years

• Development of shale resources supported 600,000 jobs in 2010

• Natural Gas prices will continue to drop

• Bad/Ugly• Ground water

contamination

• CO2 in shale released

• Radioactive isotopes released from shale– Mostly Radium & Radon

gas

• Silicon dioxide released from shale– Natural compound, but

too much – stunted plant growth and lung cancer

• The ocean absorbs carbon dioxide from the atmosphere

• Human activities release carbon dioxide into the atmosphere

• Too much carbon dioxide in the ocean has the potential to harm marine organisms and ecosystems

So, what is it?• Between 1751 and 1994

surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 30% in H+ ion concentration in the world's oceans.

• Earth System Models project that within the last decade ocean acidity exceeded historical predictions

• Could undermine the functioning of marine ecosystems and many ocean goods and services

Estimated change in sea water pH caused by human created CO2 between the 1700s and the

1990s, from the Global Ocean Data Analysis Project (GLODAP) and the World Ocean Atlas

How is atmospheric CO2 responsible for ocean acidification?

When CO2 dissolves in seawater, carbonic acid is produced via the reaction:

This carbonic acid dissociates in the water, releasing hydrogen ions and bicarbonate:

The increase in the hydrogen ion concentration causes an increase in acidity, since acidity is defined by the pH scale, where pH = -log [H+] (so as hydrogen increases, the pH decreases). This log scale means that for every unit decrease on the pH scale, the hydrogen ion concentration has increased 10-fold.

One result of the release of hydrogen ions is that they combine with any carbonate ions in the water to form bicarbonate:

This removes carbonate ions from the water, making it more difficult for organisms to form the CaCO3 they need for their shells.

“Battle” for carbonate!

• Organisms must use more energy or make less hard part material

• Existing hard parts dissolve (chemical reaction goes “the wrong way”)

From the wikimedia free licensed media file repository

Calcite(hexagonal)

Aragonite(orthorhombic)

All CaCO3 shells are not created equal

10 g

10 g

Calcite

Aragonite

Decreasedocean pH

(more acidic water)

8 g

5 g

Calcite

Aragonite

Ocean acidification: Impacts on individual marine organismsReduced fertilization of gametes in corals and other marine organisms

• Deformed flagellum in sperm that impacts their swimming• Fitness effect: lower population growth

Albright et al. 2010

Normal

Acidic

Natural range in the ocean

Ocean acidification: Impacts on individual marine organismsReduced hearing ability in anemone fish (clown fish) larvae

• Deformed morphology of CaCO3 fish ear bones (otoliths)• Disruption of acid-base balance in neuro-sensory system• Fitness effect: lower survival due to higher predation.

Simpson et al. 2011From the wikimedia free licensed

media file repository

Ocean acidification: Impacts on ecological communities

Tropical Oceans Predictions: • Corals will become increasingly rare• Algae will become more abundant• Because coral reefs support so many animals, biodiversity will decline

Hoegh-Guldberg et al. 2007

Ocean acidification: Impacts on individual marine organisms

Amount of dissolved carbon

Ph

oto

syn

thesis

Gro

wth

Non-calcifying marine algae: Increased photosynthesis and growth• Lower pH means more dissolved CO2 for photosynthesis to fuel growth• Fitness effect: higher survival and population growth

Chen & Durbin 1994

Bioremediation• Some types of pollution can be reduced, and habitats

restored, with the help of living organisms.

• Use microorganisms, fungi, green plants or their enzymes to return the environment altered by contaminants to its original condition.

• may be employed to attack specific soil contaminants, such as degradation of chlorinated hydrocarbons by bacteria.

• An example of a more general approach is the cleanup of oil spills by the addition of nitrate and/or sulfate fertilizers to facilitate the decomposition of crude oil by indigenous or exogenous bacteria..

Bioremediation• Remember the

Chernobyl Nuclear Disaster?

• Use of genetic engineering to create organisms specifically designed for bioremediation has great potential.

• The bacterium Deinococcus radiodurans (the most radioresistant organism known) has been modified to consume and digest toluene and ionic mercury from highly radioactive nuclear waste.

Bioremediation• Septic tanks and leach

beds removes waste from water and buts the water back into the ground.

• Larger scale sewage systems are actually very complex ecosystems– Have wastewater lagoons– Water sits here for 30 days

• Algae grow in the lagoon, photosynthesize and give off O2.

• Allows aerobic bacteria to grow and digest organic matter and kill fecal bacteria.

Summary• Photosynthesis, and

the production of O2, used to balance out the release of CO2 from respiration.

• However, with the destruction of over half the worlds Rainforests, CO2 levels are much higher– Also due to the

growth of industry and modern transport systems

The end!

Any Questions?