Environmental Geochemistry I. Aleš Bajer

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1 Environmental Geochemistry I. Aleš Bajer Tento projekt je spolufinancován Evropským sociálním fondem a Státním rozpočtem ČR InoBio CZ.1.07/2.2.00/

2 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

3 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

4 Environmental Geochemistry Selected topics: Atmosphere Structure of the atmosphere Composition of the atmosphere Origin and evolution of atmosphere Human impact on the atmosphere

5 Environmental Geochemistry Selected topics: Biosphere Biogeochemical evolution, Gaia hypothesis Waste and Waste management Mineral and energy resources Alternative energy resources

6 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.)

7 Environmental geochemistry Exam: Possible after presenting your seminar work and handing over it in writing form. written test

8 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

9 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

10 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

11 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: km thick, composed mostly of granitic rocks

12 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

13 Structure of the Earth

14 Structure of the Earth

15 Structure of the Earth

16 Structure of the Earth

17 Structure of the Earth

18 Earthquakes Structure of the Earth - 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

19 Structure of the Earth Earthquakes damage - landslides - tsunamis

20 Structure of the Earth Earthquakes damage

21 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

22 Volcanoes Structure of the Earth

23 Volcanoes Structure of the Earth

24 Structure of the Earth Volcanoes forming of Caldera

25 Mass Wasting Structure of the Earth -main factors: steepness of the slope rock type and layer orientation water and vegetation earthquakes and volcanoes

26 Structure of the Earth Types of Mass Wasting

27 Minerals Principles of Geology - 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

28 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

29 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

30 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

31 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

32 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

33 Rocks Relative abundance of sedimentary rocks

34 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

35 Rocks Rock cycle: rocks are continously changed over geological time

36 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

37 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

38 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 CaCO 3 - 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

39 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

40 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

41 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.)

42 Time

43 Climate impact on Soil

44 Brief history of life Human precursors 8 5 mil. years Primitive man 1 mil. Years Homo sapiens sapiens years

Review - Unit 2 - Rocks and Minerals

Review - Unit 2 - Rocks and Minerals Base your answers to questions 1 and 2 on the diagram below, which shows the results of three different physical tests, A, B, and C, that were performed on a mineral.