Download Environmental Geochemistry I.

Environmental Geochemistry I.
Aleš Bajer
Tento projekt je spolufinancován Evropským sociálním fondem a Státním rozpočtem ČR InoBio – CZ.1.07/2.2.00/28.0018
Environmental Geochemistry
Selected topics:
The Earth and Lithosphere
The structure of the Earth
Principles of Geology
Internal (endogenic) processes: Plate tectonics, Earthquakes,
Volcanoes
Surface processes: Weathering, Mass Wasting
Principles of Soil Science
Environmental Geochemistry
Selected topics:
Water and hydrosphere
The hydrologic cycle
Oceanic circulation
Composition of sea water
Fresh water
Ground water
Glaciers and Ice Ages
Desert and desertification
Human impact on water
Environmental Geochemistry
Selected topics:
Atmosphere
Structure of the atmosphere
Composition of the atmosphere
Origin and evolution of atmosphere
Human impact on the atmosphere
Environmental Geochemistry
Selected topics:
Biosphere
Biogeochemical evolution, Gaia hypothesis
Waste and Waste management
Mineral and energy resources
Alternative energy resources
Environmental geochemistry
Seminar work:
themes:
Ecological problems of your hometown or country
Geochemistry – current important problems
for example : Expansion of solar energy in CZ
Fresh water pollution (Brno dam)
Motor - vehicle traffic in cities
etc…….
- 5 pages max.
- PowerPoint presentation (15 - 20min.)
Environmental geochemistry
Exam:
Possible after presenting your seminar work and
handing over it in writing form.
written test
Structure of the Earth
Theory of Earth layers
- Core: Fe, Ni
Inner Core
Outer Core
- Mantle: denser than Crust,
Fe, Mg, Silicates
- Crust: thin surface layer
(8 elements, O, Si, Al, Fe,
Ca, Mg,K, Na)
Continental crust
Oceanic Crust
Structure of the Earth
Theory of Earth layers
- Hot layer „Asthenosphere“
between Mantel and Crust
- Rigid crust floats on
plastic Asthenosphere
Plate tectonics theory
- above surface layers:
Hydrosphere
Atmosphere
Biosphere
Structure of the Earth
Geochemical classification of the elements
-lithophiles: elements concentrated in the crust
Si, Al, Mg, Ca etc.
- chalcophiles: element (metal) concentrated in crust combination
with sulfur - Cu, Zn, Pb, Sn etc. important ore minerals
-siderophiles: element concentrated in core – Ni, Fe, Co, Pt, Au…
-atmosphiles: volantile elements, concentrated in the atmosphere
H, N, He, innert gasses
Structure of the Earth
The Earth´s Crust
-The thinnest and outermost layer (cool, rigid, brittle)
- Two types:
Oceanic crust : 5-10 km thick, composed mostly of basalt
Continental crust: 22 – 50 km thick, composed mostly of granitic
rocks
Structure of the Earth
Plate Tectonics
- The rigid lithosphere floats on the asthenosphere
- the litosphere is broken into seven large and several small plates
- plates moved in different directions
- three types of plate boundaries
Structure of the Earth
Structure of the Earth
Structure of the Earth
Structure of the Earth
Structure of the Earth
Structure of the Earth
Earthquakes
- is a vibration generated by sudden slippage of rocks along
the fault
- occur along tectonic plate boundaries
- produce seismic waves (primary waves P, shared waves S)
- measurement by seismograf
Structure of the Earth
Earthquakes damage
- landslides
- tsunamis
Structure of the Earth
Earthquakes damage
Structure of the Earth
Volcanoes
- Magma forms in three geologic environments:
subduction zones
spreading centers (ridges) especially mid-oceanic ridges, basaltic magma
mantle plumes (hot spots), Hawaiian Islands
- many types of volcano exist
Structure of the Earth
Volcanoes
Structure of the Earth
Volcanoes
Structure of the Earth
Volcanoes – forming of Caldera
Structure of the Earth
Mass Wasting
-main factors: steepness of the slope
rock type and layer orientation
water and vegetation
earthquakes and volcanoes
Structure of the Earth
Types of Mass Wasting
Principles of Geology
Minerals
- fundamental building component of rocks
- natural, anorganic, with crystaline structure and
characteristic chemical composition
- made up of elements (gold, quartz, pyroxene)
Main rock forming minerals
- only 20 of 3000, 10 = 90% rocks
(Feldspar, Pyroxene, Amphibole, Mica, Clay Minerals,
Olivine – Quartz, Calcite, Dolomite)
Important mineral groups
- oxides, sulfides, sulfates, halides, carbonates, phosphates,
native elements, silicates
Minerals
Feldspar
- more than 50% of the Earth´s crust
- major component of common rocks
- 2 groups: orthoclase (K)
plagioclase (Ca, Na)
- resourse of mineral nutrients
Pyroxene
- dark colour
- Mg, Fe
- occur in mafic rocks
Amphibole
- similar to pyroxene
- more stabile than pyroxene
Minerals
Mica
- plate shaped
- muscovite (K)
- biotite (Fe, Mg)
- occur in continental crust (igneous and metamorphic rocks)
Clay minerals
- formation from Feldspar by weathering
- small crystals
- occur in surface rocks (sedimentary)
- important component of soil
Olivine
- green
- mainly in oceanic rocks
- togehter with pyroxene in mantle rock
Minerals
Carbonates
- calcite, dolomite
- near surface
- made up of organism bodies (corals)
- occur in sedimentary rocks (limestone)
Other important minerals
Ore minerals
- pyrite, chalcopyrite, galena, sfalerite – metal ore
- gold, silver, copper
- halite, gypsum, barite – building material
Accesory minerals
- rock forming (small amount)
- chlorite, serpentinite, garnet, limonite, epidote
Rocks
3 main types:
igneous, sedimentary, metamorphic
rock cycle
igneous rock – weathering – sediments – litification – sedimentary
rock – metamorphism – metamorphic rock – melting – magma –
solidification – igneous rock
There could be more variants of cycle.
Igneous rocks
- forms from magma
- 2 group: intrusive (volcanic) rocks, plutonic rocks
- granite – rhyolite, diorite – andesite, gabro - basalt
Rocks
Sedimentary rocks
- made up of all kinds of rocks during the weathering (decompose)
- devided into three types: clastic, organic and chemical
clastic can be:
disintegrated (unconsolidated) – small fragments rocks: clay, silt,
sand, gravel
consolidated (cemented) – fragments are lithified by solution
under the pressure: conglomerate, sandstone, shale, limestone
- most widespread rocks on the surface
- formed by process called erosion
- important term is a transport by wind, gravity, stream …..and
deposit
- main soil forming rocks
- limestone can be formed by clastic, organic and chemical
processes
Rocks
Relative abundance of sedimentary rocks
Rocks
Metamorphic rocks
- formed by sedimentary and igneous rocks during increased
temperature and pressure
- at metamorphism the composition and the texture are changing
- special metamorphic minerals: garnet, actinolite, chlorite,
sillimanite…
- the texture is changing to coarser grain, layer texture (foliation)
- limestone – marble
- sandstone – quartzite
- shale – low slate, middle schist, high gneiss
- other metamorphic rocks: amphibolite, eclogite, granulite
Rocks
Rock cycle: rocks are continously changed over geological time
Soils
- thin layer formed by interaction among lithosphere, atmosphere,
hydrosphere and biosphere, so called pedosphere
- contain 4 substances: mineral matter, organic matter, air, water
- a thin, fragile and vanishing resource
- soil is the basic natural resource (Aldo Leopold)
- important process is weathering (decomposition and desintegration)
- two types of weathering: mechanical and chemical
Soils
- mechanical weathering is desintegration of rock into small pieces
and 6 main processes are involved here:
- unloading – causes the small cracks and thin layers
- freezing and thawing – expansion force of water, occur in daily
cycle
- heating and cooling – contraction and expandion is different for
different colour of minerals and rocks, this changes lead to
exfoliation
- wetting and drying – important at clay minerals
- organism – generally reduces size of rocks and minerals
- chemical weathering is decomposition of minerals and rocks
as chemical reactions transform them into new chemical
combinations, there are involved 6 main processes
Soils
- chemical weathering is decomposition of minerals and rocks
as chemical reactions transform them into new chemical
combinations, there are involved 6 main processes
- dissolution – is dissolving of solid in liquid, for example NaCl
and CaCO3
- hydrolyses – is procces of reaction with water to form
hydroxydes, very important for soil forming
- acidification – natural water is weak acid that dissolves
minerals and rocks, some manmade air pollutants make up
strong acid that accelerates natural chemical weathering
- hydration – is combination of a solid mineral with water, this
reaction causes increasing of chemical structure
- oxidation – very important on surface, mineral reaction with
oxygen, most evident in iron-rich minerals
- reduction – important process in stagnant water condition –
grey-blue colour is typical
Soil profile
- soil body consists of several layers called soil horizons
- on surface there is material called litter (dead plant or animal
matter)
- surface horizon – O horizon
mixture of organic component (litter and humus) and small
amount of minerals
- A horizon
mineral horizon that is dark colour due to high contents of
organic matter, it is mixture of sand, silt and clay
- E horizon
develops zone of elluviation (leaching), all matter is removed
down, typical light colour (white colour)
-B
horizon
horizon of accumulation or illuviation, typical brown colour
due to iron mineral coloids
Soil profile
-C
horizon
zone of litter altered parrent material by soil-forming processes
Main processes:
- additions, for example organic matter
- losses (leaching)
- translocations, movement of organic
matter, clay, nutrients from one layer
to another
- transformation, clay, primare
minerals to secondary minerals
Soil forming factors
- Parent rock
strong influence that sinks during the time, provides nutrients
- Climate
influence on horizons development
- Geomorphology
orientation of slope, northern slope means more intensive and
deep development of soils
southern slope means retarded development of soils
- Time
more older = more differential soil profile
- Man
fertilization, erosion, occupation of quality land (stocks etc.)
Time
Climate impact on Soil
Brief history of life
Human precursors 8 – 5 mil. years
Primitive man 1 mil. Years
Homo sapiens sapiens 40.000 years