THE PHYSICAL ENVIRONMENT

PHYSICAL VARIABLES and THE ABUNDANCE OF PLANTS & ANIMALSLocal distribution patterns and abundance of species are limited by ABIOTIC FACTORS such as: - Water- pH -Soil- Light- Temperature- Wind

What is Soil?A complex mix of eroded rock, minerals, water, decaying organic matter, air, and billions of living organisms, most of the microscopic decomposers.

Soil ImportanceAll fleshy fruits and vegetables are made up of soil nutrients.Grow wood to make paper and fiber.Grow plants to extract medicinal compounds.Helps to purify water we drink.Recycles nutrients.

Soil ProfileSoil TextureSand

Silt

Clay

Soil composition:Minerals (sand, silt, clay) - 45% contentAir - 25% contentWater 25% content Humus (living and dead) - 5% content

Soil formation:Weathering [Mechanical or Chemical]Erosion

SOIL STRUCTURE IN BELIZEMost common: Limestone (CaCO3)Least common: Granite (quartz)

Soil ClassesMollisols Best for agricultureOxisols - Rain forestAlfisols - SavannahAridisols DesertsUltisols - ???

LIGHT Primary source of energy for the biosphere (SUN)Visible light ranges from 400 nm- 700nm Ultra violet (UV) 700nmFunction of SUN:

Importance of Sun

Warms the planetPrevents freezing of oceansEmpower the biogeochemical cyclesDrives the process photosynthesisCreate/determine seasonsLight source (the moon & stars too)Ultimate source of energyDetermines the time of dayDrives the global climate patterns (Green House Effect or Global Warming or El Nino)

ATMOSPHERE Is a collection of gases that gravity holds in a thin envelope around earth. These gases are responsible for moderating flow of energy to Earth and are involved with the biogeochemical cycling of many elements and compounds: Nitrogen, oxygen, carbon, sulfur, water.

Composition of the Atmosphere:Nitrogen - 78%Oxygen - 21%Water Vapor 0 to 4%Carbon Dioxide - .037%Other gases make up the rest { NAME 2? }

Atmospheric Layers8 layers are defined by constant trends in average air temperature (which changes with pressure and radiation), where the outer exosphere is not shown.

TroposphereTropopauseStratosphereStratopauseMesosphereMesopauseThermosphereExosphere

Heterosphere - N2 and O2 are not uniformly mixed

Homosphere - N2 and O2 are uniformly mixed

Composition

OZONE LAYERUV light has high energy levelOzone in upper atmosphere absorbs strongly in ultraviolet portionChlorofluorocarbons react with and destroy ozone:- ozone holes appear in the atmosphere- concern over this led to high controls on CFCs & other substances depleting ozone

Figure 3: Humans cause more damage to the ozone layer than any other source.Source: Geocities.com, 1998

WaterFavorable for maintenance of life! Abundant 71%Universal solvent Enables movement of organismsCohesion is responsible for the transport of the water column in plants

Expands further upon freezingBuoyancy of water is maintainedBottoms of lakes and oceans dont freezeFloating ice provides insulating surfaces

Properties of WaterPolar moleculeCohesion and adhesionHigh specific heatDensity greatest at 4oCUniversal solvent of life

All natural water contain dissolved substances:Dissolve gases and trace minerals (rain water)Dissolved minerals Ca2+ , HCO3-, SO4 (freshwater)Dissolved minerals Na+ , Cl- , Mg2+ , SO4 (marine)

Water Medium Nutrients levelsEssential yet limited nutrients include Nitrates & Phosphates;Typical Freshwater (N > P)Typical Marinewater (P > N)

Water/Hydrology Cycle

Research Assignment [In Notes]:What are common disturbances to the water cycle?

How is the natural ecosystem disrupted with these disturbances?

What measures can be instituted to combat/remedy the disturbances?

pHMeasures the degree of acidity (0 14)Measures the conc. of H+ SCALE: (7Base)Most biologic fluids are in the pH range from 6 8pH range of surface waters: 6 9Acid rain lowers pHDissolve mineralsDenature plant cells and increase organism death Extremely high pH is also toxic to organisms

Acids and BasesAn acid is a substance that increases the hydrogen ion concentration in a solution.Any substance that reduces the hydrogen ion concentration in a solution is a base.Some bases reduce H+ directly by accepting hydrogen ions. Strong acids and bases complete dissociate in water.Weak acids and bases dissociate only partially and reversibly.

BuffersA substance that eliminates large sudden changes in pH.

Buffers help organisms maintain the pH of body fluids within the narrow range necessary for life. Are combinations of H+ acceptors and donors forms in a solution of weak acids or basesWork by accepting H+ from solutions when they are in excess and by donating H+ when they have been depleted.

TEMPERATURE Organisms must cope with temperature extremes Thermoregulators (warm blooded)Upper limits for plants and animals is 45oCSome bacteria can withstand 75oC 110oCTo resist Freezing organisms:EndothermicActivate prodn of glycerol/glycoproteins (anti-freeze)High Temperatures:Denature proteinsAccelerate chemical processesAffect properties of lipids

UNDERSTANDING HEAT TRANSFERHeat isEnergy given off or absorbed by an objectA measure of the motion of the molecules in an objectThe total amount of molecular energy in an objectWith regards to Heat Transfer Heat always moves from a warmer place to a cooler place. Hot objects in a cooler room will cool to room temperature. Cold objects in a warmer room will heat up to room temperature. Heat transfers in three ways: Conduction Convection Radiation

WEATHER & CLIMATEWeather- refers to daily conditionsrainfall, temperature, humidity, cloud cover

Climate- average weather over a long period Average temperature, average precipitation determines climateClimate determines plant and animal life in the major biomesMETEOROLOGY - Scientific study of the atmosphere, both weather and climate

Temperature oF, oC (Celsius or Centigrade), K (Kelvins)

Humidity % relative to saturation, g/kg, kg/m3

Wind Velocity Knots, mph Meters per second (m/s) or (m s-1)

Pressure Inches Hg, mm Hg, mb, Pa, hPa (1hPa = 1mb)

Gaseous Concentrations ppmv: parts per million by volumeClimatological Variables and measurements

Global air circulation & its effects on regional climatesTemperature & precipitation patterns leads to different climates (due to air circulation)

5 factors determine global air circulation:Uneven heating of earths surfaceSeasonal changes in temp and precipitation (seasons).Rotation of the earth on its axisProperties of air and waterLong term variations of atm. Solar energy striking the earths surface

INFLUENCE OF HUMANS ON CLIMATEGlobal Warming - increase in Earth's surface temperatureHuman activities are primarily responsible for global warming, through an increase in greenhouse gasesGREEN HOUSE EFFECT: warming effect of the troposphere

The Greenhouse Effect and Global Warming The sun produces radiation mainly in the ultraviolet (UV), visible (vis) and infrared (IR) regions of the electromagnetic spectrum. When these reach the Earth, part is reflected back into space and part of it is absorbed by the Earths surface. The part which is absorbed heats up the Earth which in turn then radiates some of its energy out into space.The frequency at which any object emits radiation depends on its temperature. The Earth, being that much cooler than the Sun, emits energy at a lower frequency and therefore longer wavelength in the IR region.

Explain why some gases in the atmosphere cause the greenhouse effect.

Name 4 other greenhouse gases and site sources of these gases.

In your own words, explain the relationship between greenhouse effect and global warming.Summarise the possible causes of climate change;Site evidence of environmental changes or degradation caused by climate change in Belize.

Biogeochemical CyclesCycling of matter within the ecosystem from biotics to abioticsMajor cycles are: C , N , P , O , H2O , S

Carbon Cycle:Cycling of carbon thru. The atm , earth, oceans , plants ; animals.Major reservoir is the ocean floor

Carbon Use in the environment:Components of organic structure of living thingsComponent of energy molecules (protein, carbs)Involved in photosynthesis and respiration

Summary of Cycle:Carbon is added back to the atmosphere byRespiration (plant and animal)Combustion / FiresWeathering volcanoesCarbon is removed from the atmosphere byPhotosynthesisFixation (in limestones ; sediments ; heterotrophs)

Disrupted by:DeforestationExcess combustion of fossilsThe feed the phenomenon of Green House Effect and Global Warming

Carbon Cycle

Nitrogen Cycle:Cycling of nitrogen molecules in the env.80% of the earths atm is made of nitrogen ; the major reservoir is the Air.The cycle is govern by bacteriaIs summarized into 5 processes:**Nitrogen Fixation**Ammonification**Nitrification**Denitrification** Assimilation

Use of Nitrogen Component of amino acids , proteins and nucleic acidsNatural component of fertilizersNatural gas used to fix the structure of the atmosphere

Summary of ProcessNitrogen FixationConversion of nitrogen gas (N2) into ammonia (NH3)Nitrogen from the atm is fixed into living things Biological process - atm nitorgen is fixed by and into nitrogen-fixing bacteria and cyanobacteria.Also occurs by lightening , Haber Process and Combustion

NitrificationInvolves the conversion of ammonia (NH3) to nitrate (NO3-) Accomplished by soil bacteria, called nitrifying bacteria.Summed into stages, that changes the ammonia nitrite nitrate

AssimilationUptake of (NH3) and/or (NO3-) and convert it into their bodily compound Occurs when the plants are eaten by the animals too.

AmmonificationConversion of biological nitrogen in animals ammonia ((NH3) to nitrate (NO3-) production of ammonia.Occurs during waste production in organisms - like urea or uric acid

Denitrification ?????

NITROGEN CYCLE

HOW DOES THE FOLLOWING DISTRUPT the Nitrogen Cycle?

Water Pollution

Agriculture

Living organisms depend on the physical environment for energy from the sun, nutrients from the soil ***The shorter the wavelength the more energetic the light is *So far, we have seen that both air pressure and air density decrease with height above the earth

Air temperature has a more complicated vertical profile. Look at this diagram, notice that air temp normally decreases from the surface up to about 11 km (36,000 ft) or 7 mi. This decrease in air temp with increasing height is due mainly to the fact that the sunlight warms the earths surface and the surface then warms the air above it.

The rate at which air temp decreases with height is called Lapse Rate. The standard lapse rate is about 3.6F per 1000 ft of rise. Note this is only an average and is not always the case. There are times when air temperature actually increases with height. This condition is known as a temperature inversion. We use radiosondes to measure the day to day changes in the lapse rate.

Jet streams are fast flowing, narrow air currents The main jet streams are located near the tropopause, the transition between the troposphere (where temperature decreases with altitude) and the stratosphere (where temperature increases with altitude). **There is only 1 molecule out of 554,000,000 water molecules that is dissociated.

Few survive extreme temp and freezing is also harmful to the body and cellsAdaptations- some of these maintain internal temp above freezing

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