MATERIAL CYCLING IN ECOSYSTEMS Lecture 3 NS5 1st 2010-2011

THE CYCLING OF MATERIALS IN THE ENVIRONMENT

• LAW OF ECOLOGY #2: EVERYTHING MUST GO SOMEWHERE

• LAW OF THERMODYNAMICS: ENERGY IS NOT CREATED NOR DESTROYED

BIOGEOCHEMICAL CYCLING• The movement of elements and compounds that

are essential to life

• Materials are transported through organisms, the atmosphere, water and land in a series of CYCLES

• “Bio” – life, participation of organisms

• “Geo” - abiotic environment as source of nutrients

• “Chemical” – nature of substances being cycled

BASIC TYPES OF CYCLES

• Gaseous type – the reservoir is the atmosphere and/or hydrosphere (e.g. N2, CO2, O2)

• Sedimentary type – the reservoir is the Earth’s crust (e.g. Phosphorus)

• Linkage type – the reservoir includes major pathways in air, water, and crust (e.g. sulfur)

WHEN THE PROBLEMS COME IN

• Errors in Nutrient Cycling

• A’ A’’ A’’’’ A’

• Pollution – accumulation of a chemical form that is higher than the standards

• Non-biodegradable substances – change to form new chemical structure where no organism has yet to utilize it

• Reduction of the concentration of other chemical forms – limits growth of the subsequent components of the cycle

• Eutrophication - the channeling of a substance to other pathways (greater amounts of phosphates in aquatic systems)

INTRODUCING THE CYCLES OF

NATUREBIOGEOCHEMICAL CYCLES

THE HYDROLOGIC CYCLE OR WATER CYCLE

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PURPOSE: Mediates Nutrient Cycle and A Major Energy Dissipation Pathway

• IMPACTS OF HUMAN INTRUSION

• More consumption than supply

• Pumping waters from aquifers - not a normal part of the water cycle

• Garbage and wastes pollute the water and clog drainage systems induces flooding

• Asphalting – render the ground impervious to water blocks infiltration

POLLUTION: a change in transfer rate of water and nutrients that can lead directly or indirectly to a degradation of human health or degradation of plant and animal life

OXYGEN CYCLE• Type: Gaseous (21%)

• Major Reservoir: Atmosphere

• Forms: Free and Molecular Oxygen

• Sources: Photosynthesis from producer AND Photodissociation of Water Vapor

• Fate of Free O2:

• Reach higher levels of trophosphere and reduced to ozone (provides protection by filtering out the sun's UV rays)

• May react with chemicals and organic compounds of the earth’s crust

• May be used up in cell respiration which release CO2 to be used by autotrophs to produce more O2

IMPACTS OF HUMAN INTRUSION

• CFC’s (chlorofluorocarbons) deplete ozone layer “ozone hole”

• Eutrophication (nutrient enrichment from agricultural and domestic wastes) leads to depletion of oxygen in water

• Combustion of fossil fuels and removal of vegetation (deforestation) deplete the supply of oxygen in the atmosphere

CARBON CYCLE• Type: Gaseous Cycle

• Major Reservoir : Atmosphere but also calcium carbonate in shells and limestone, as well as fossil fuels

• Significance : Major element of organic compounds; building blocks of all biomolecules

• Processes

• Photosynthesis removes CO2 while respiration and combustion add CO2 to the atmosphere.

• CO2 from air and water combine to form bicarbonate (HCO3) – source of carbon for aquatic producers. Carbonic acid makes rainwater also slightly acidic

• Similarly, when aquatic organisms respire, CO2 is released and combine with water to form HCO3. HCO3 (water) = CO2 (air)

The global carbon cycle includes the earth's atmosphere, oceans, vegetation, soils and fossil fuels

CARBON RESERVOIRS

CONTROVERSIAL ISSUES ASSOCIATED WITH CARBON CYCLE

NITROGEN CYCLE• Type: Gaseous Cycle

• Major reservoir – ATMOSPHERE

• Importance – Essential for many biological processes, constitutes part of proteins (amino acids), in bases of nucleic acids that make up DNA and RNA

• 79% of atmosphere is made up of nitrogen (N2) but this is INERT

• It must be fixed for organisms to utilize it

IMPACTS OF HUMAN INTRUSION

• USE OF NITROGEN FERTILIZERS

• Human use of nitrogen fertilizers causes runoff, leading to eutrophication in aquatic systems (e.g. eutrophication)

• NITRATES LEACHING INTO GROUNDWATER

• Nitrogen level in drinking water rises

• A large rise of nitrogen in drinking water supplies leads to Methemoglobinemia / Blue-Baby Syndrome

• NITROGEN OXIDES RELEASED THROUGH COMBUSTION

• Burning of fossil fuel + automobiles : source of nitrogen dioxide

• Ozone + PAN Photochemical Smog

• LIVESTOCK RELEASE OF LARGE AMOUNTS OF AMMONIA (FROM WASTES)

• The ammonia released from wastes of livestock can have detrimental effects on fish and other organisms

• There is reduction in diversity

PHOSPHORUS CYCLE• Type: Purely Sedimental

• Major reservoir – Earth’s crust

• Gradual cycle - It has no gaseous phase

• Phosphorous normally occurs in nature as part of phosphate ion.

• Most phosphates found as salts in ocean sediments or in rocks.

• Over time : geologic processes can bring sediments from ocean to land, and weathering can bring it from land to ocean

• Importance

• Phosphorous constituent of nucleic acids in DNA, and energy currency of cell ATP.

• Phosphorous -also found in bones, in phospholipids which are found in biological membranes.

IMPACTS OF HUMAN INTRUSION

• Humans mine phosphate ores for use in fertilizer production and detergents

• Human actions could lead to eutrophication of aquatic systems which cause algal blooms

• Algal blooms cause fish kills

SULFUR CYCLE• Type: Sedimentary cycle with atmospheric

component

• Major reservoir – inorganic sulfur in rocks and fossil fuel

• Biological Importance

• Sulfur is an important element in protoplasm which is an important component of some amino acids.

• Sulfur is part of proteins, vitamins and hormones

CONTROVERSIES ASSOCIATED WITH THE

SULFUR CYCLE

ACID RAIN

THE CYCLING OF HEAVY METALS

BIOMAGNIFICATION AND BIOREMEDIATION

MERCURY• Fish can be contaminated with

methylmercury from neighboring industrial plants

• They discharge mercury wastes into water

• Result : Minamata disease or Mercury Poisoning

• Effects : blindness, deafness, lack of coordination, intellectual deterioration

CADMIUM• Itai-itai disease is cadmium poisoning,

first in Japan 1950

• Cadmium was released into the river by mining companies in the mountains

• Causes softening of the bone, and kidney failure

• Name of disease derived from painful screams because of severe pain in joints and spine of victims “pain-pain”

LEAD• Lead poisoning =

Increases level of lead leads to negative effects on nervous and reproductive system

• e.g. Lead containing gasoline, Paints, Batteries, Electric Wires, Cables etc

HYDROCARBON• DDT – (dichlor-diphenyl-

trichloroethane) “organochlorine insecticide”

• Banned in 1972

• Exposure to DDT causes eggshell thinning in bird species eg. raptors, eagles, peregrine falcons

• Toxic to humans and animals when swallowed or absorbed through the skin

BIOLOGICAL MAGNIFICATION• It is the increase in concentration of an element

or compound that occurs in the food chain as a result of food chain energetics or degradation of substance.

• Accumulation of chemicals in higher predators or in higher trophic levels

• Chemical concentration is said to be magnified thousand fold in tissues of higher trophic level organisms

• It is important in ecology because : it indicates that solution to certain types of pollution is not dilution because food chains will concentrate the pollutant

ANSWER : BIOREMEDIATION

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POPULATION