GEOPEDOLOGY module outline 1 Introduction to the study

GEOPEDOLOGY: module outline 1) Introduction to the study of soil 2) Parameters for soil characterization 3) Description, classification and cartography of soil 4) Soil degradation process 5) Characterization of contaminated soils 6) Soil quality 7) Case studies 8) Practical activities 1

Topics to develop during the project work • Pesticide soil pollution and its consequence for the ecosystems (herbicides, fungicides, insecticides, etc) • Heavy metals soil pollution and its consequence for the ecosystems (Pb, Hg, Cd, Zn, Cu, Ni, As, etc. ) • Organic industrial compound soil pollution and its consequence for the ecosystems (PCB, PAH, etc. ) • Radionuclides soil pollution and its consequence for the ecosystems • Nutrient soil pollution and its consequence for the ecosystems (N, P, K, etc. ) • Microbiological soil pollution and its consequence for the ecosystems 2

The soil: introduction Ciro Gardi - Dipartimento di Scienze Ambientali, Parma ciro. gardi@unipr. it Alfisuolo su deposito morenico (Val di Susa) 3

Lecture outline þ þ Soil: definition Soil function Soil forming process Soil forming factors: þ rocks and parent material þ topographic factor þ climate þ biotic factor þ time þ þ Mineral weathering Organic matter trasformation Soil classification Different soil profile 4

SOIL A soil is a three-dimensional natural body, superficial, more or less continuous, deriving from the weathering process of earth surface and the trasformation of organic matter. A Soil B BC C 5

REGOLITH The regolith is a layer of unconsolidated debris deriving from the physical degradation of earth surface Regolith 6

AGRICULTURAL SOIL The complex formed by solid materials derived by the action of climate, biota and man on the most superficial part of the earth crust, untill it become able to support the cultivation of crops. Agricultural soil 7

Function of soil in our ecosystem • Medium for plant growth: terrestrial ecosystems are based on soil • Regulator of water supplies: interactions between soil and water determine quality and quantity of water • Recycler of raw material: the soil system plays a fundamental role in the major geochemical cycles • Habitat for soil organism: due to the tremendous range of habitats, soil biodiversity is extremely high • Engineering medium: the soil represent a base on which building, road, and other structures are made 8

Pedology • Pedology is the branch of soil science investigating soil genesis, soil survey and mapping, interpretation and soil behavior • the origin of pedology were established by Dokuchaef in 1883 Basic concept • the soil is a particular environment resulting from a continuous pedogenetic process • the influence of climate on pedgenesis is prevailing respet to the other factors • the investigation of soil genesis is crucial to the deep comprehension of soil characteristics and behavior 9

Soil forming process Is the group of processes that, taking palce on parent material, determine the soil formation. These processes are the transformation, migration and deposition of minera and organic materials. 10

Soil forming process classification • decomposition and transformation of mineral and organic materials and subsequent creation of new compounds • migration of mineral and organic compounds • deposition of mineral and organic compounds 11

Soil forming factors • • • bedrock, parent material topography climate time biotic factors anthropic factors Phases in soil forming process • I PHASE – physical degradation of mineral – accumulation of fine textured mineral materials – accumulation of organic materials • II PHASE – eluviation and illuviation of mineral and organic materials – neogenesis of mineral and organic materials 12

Jenny equation (1941) s = f(cl, o, r, p, t, h) - cl = climate - o = organism - r = morphology (mainly position in landscape) - p = bedrock and parent material - t = time - h = anthropic factor 13

Bedrock Is the original material on which the decomposition and weathering processes will take place originating the parent material CLASSIFICATION: • magmatic: • intrusives (granito, diorite, gabbro) • effusives (riolite, andesite, basalto) • sedimentary: • di deposito meccanico (arenaria, marna) • di deposito chimico (gesso) • di deposito biochimico ( calcare, dolomia) • rocce metamorphfic: • teermometamorfiche (marmo) • dinamometamorfiche (gneiss, micascisti) • termodinamometamorfiche (anfiboliti) 14

Rock degradation Chemical, physical and biological processus that lead to the degradation of rock structure • are influenced by: • • permeability porosity coesion particle size thermic conductivity chemical composition of cements climate chemical characteristics of precipitation 15

Degradation process • physical: • • thermoclastism crioclastism aloclastism pressure determined by plant roots • chemical: • • • dissoloution hydrolisis hydratation oxidation carbonatation • biological: • colonization by vegetal organism 16

Parent material • is represented by the original material from which the soil is originated • can be formed by mineral and organic materials • can be classified according the following scheme: • residuals • transported • organic 17

Topography and morphology Morphological characteristics of a territory play an important influence on soil forming process; in particular they influence: - erosion and deposition process - micro-climate - vegetation type and distribution - soil moisture regimen 18

Erosion and deposition • high slope angles promote soil erosion (sheet and rill erosion) • reduction of inclination along a slope promotes soil deposition • the moderate slope angles promote the infiltration of water into the soil • a consequence of these process is the creation of soil catenas 19

Climate and soil The relationships between climate and soil were noted since the beginning of soil science (Dokuchaef, Hilgard) 20

Climate classifications: Lang or “pluviometric factor” The climate classification is obtained on the base of the ratio between rainfall and annual average temperature • P/T > 160 • cold region soils “podzol” P/T from 160 to 100 steppe region soils: “chernozem or black soils” • P/T from 100 to 60 temperate region soils: “brown soils” • P/T from 60 to 40 sub-tropical and tropical region soils: “yellow and red soils” • P/T < 40 arid region soils: “salt soils” 21

Time required for the genesis of different soils Soil type volcanic ash mud deposit A horizon on a loess organic on peat podzol on sand ultisols (Australia) oxisols (Africa) years/cm 1, 3 0, 1 12 - 80 15 21 100 750 22

Biotic factor • Plants and microrganism: – – miro-climate rocks weathering sinthesis of organic matter (o. m. ) degradation of o. m. • Animals: – decomposition of o. m. – degradation of o. m. – distribution of o. m. – structure and physical characteristics of a soil 23

Food chains • Primary producers: – plant residues (organs, tissue, cells) – root exudates – food for primary consumers • Primary consumers: – herbivores • Secondary consumers: – parassites – predators • Tertiary consumers: – parassites – predators • Detritivores 24

Relationships between organic matter and biomass in the soil • It is possible too estimate that a percentage between 1 and 8 of soil organic matter is represented by living organisms; consequently higher is the organic matter content, higher will be the biologica activity rate. • The most important actors in soil life are microrganism and earthworm/thermite. • For a soil with 2% of o. m. and 1 m depth, it is possible to estimate the following values: – orgnaic matter 200. 000 kg/ha – organic detritus 20. 000 kg/ha – microbial biomass – soil fauna 2. 000 kg/ha 25

Soil composition Gaseous phase Liquid phase Solid phase: - mineral - organic 26

Time Is the dimension within which the soil forming factors interact Rock time Parent material Weakly developed soil Well developed soil 27

Time In the soil genesis it is often possible determine the beginning of the process (t 0); this knowledge is useful for the comprehension of soil forming process: – – volcanic eruption drainage of an area alluvial, colluvial, aeolian deposition erosion 28

Mineral weathering Mineralogical composition of some rocks: – granite: • ortoclasio, quarzo – plagioclasio, biotite, pirite, zircone, tormalina – gabbro: • plagioclasi, pirosseni – olivina, ilmenite, apatite, ematite – basalto: • plagioclasio, pirosseno – magnetite, ematite, ilmenite, apatite, quarzo – calcare: • calcite – limonite, emetite, dolomite 29

Weathering rate of minerals The weathering rate of the minerals is affected by: – mineral intrinsic stability (resistance to hydrolitic process) – p. H – presence of complexant substances – temperature – specific area of the mineral – efficiency in the removal of weathering products dissolution rate (25°C, p. H 5) – – quartz K-feldspar Na-feldspar Ca-feldspar 4. 1 x 10 -14 moli m-2 sec-1 1. 7 x 10 -12 moli m-2 sec-1 1. 2 x 10 -11 moli m-2 sec-1 6. 6 x 10 -9 moli m-2 sec-1 30

Decomposition rate of organic materials – complex proteins – hemicellulose – fats, waxes, ecc – lignine Time for the decomposition process – sugars, starch, simple proteins 31

Organic matter mineralization – enzymatic oxidation of carbon compound R-CH 4 + 2 O 2 ossidazione enzimatiche CO 2 + 2 H 2 O + energy – demolition of proteic molecules – release of fertility elements – sinthesis of new organic compounds, more resistant to microbic degaradation 32

Humus 33

Humus genesis fresh organic matter fast mineralization simple compounds precursor humic acid sinthetis fresh humus maturation stabilized humus slow mineralization CO 2 H 2 O energy 34

Humus characteristics – stability: • the most stable type can last thousands of years in the soil – complex with clay: • the organic material i s protected by a clay coating against the fast mineralization – colloidal behavior: • very small size, high specific area, electric charge on the surface – organo-mineral complex 35

Influence of organic matter on soil properties – physical properties: • • structure water ritention water infiltration color – chemical properties: • • • cation exchange capacity mineral weathering and cation availability nutrient reserve reduction of negative effect of toxic elements reduction of negative effects of xenobiotics – biological properties: • direct relationships between organic matter and biomass 36

Humus classification • p. H >7, C/N 10 – mull forestale • p. H 5, C/N 12 -15 – moder • p. H 4 -5, C/N 15 -25 – mor • p. H 3, 5 -4, 5, C/N 25 -40 – anmor • p. H var. , C/N <20 – oligotrophic peat • p. H 3, 5 -4, C/N 30 -40 – mesotrophic peat Decreasing biological activity – mull calcico • p. H 7 -7, 5, C/N 15 -30 37

Migration process • Descendant • Ascendant P - ET > 0 P - ET < 0 soil grounwater 38

Migration process • cations (Ca, Mg, K, Na) • salts (solfati, cloruri, nitrati) • oxides and hydroxides (Fe, Al, Mn) • humus • clay • silica 39

Soil profile O - organic horizon A, E - eluvial horizons B - illuvial horizons C/D - parent material/ bedrock 40

Factors influencing the migration process • Precipitation and ET • soil texture and structure • capillary fringe • p. H • redox potential • humus 41

Podzoliztion cold climate O • acidi organici humus lisciviazione alterazione argille A • hight soil moisture, anoxic environment and low temperature promote fulvic acid sinthetis and the mineral weathering • the fulvic acids allow the solubilization of iron and alluminium oxides humus, Fe, Al, Si, Ca, Mg, N, K, Na accumulo di humus Fe e Al promoted by low cation parent material and cold climate B • in B horizons Fe, Al and fulvic acids precipitate • neogenesis of clorite clay perdita di N, Ca, Mg Na, K 42

Leaching temperate climate O acidi organici lisciviazione argille, accumulo s. o. A • in some case all cations are removed from the exchange complex • a further step is represented by the leaching of clay, Fe and Al hydroxides argille, Ca, Mg, Na, K accumulo argilla, Ca Fe, riassorbimento basi • Soluble salt, calcium carbonate and cations are progressively leached B perdita parziale di Ca, Mg, Na, K 43

Laterization tropical climate O acidi organici Intensi fenomeni di alterazione accumulo Fe e Al A • there is a lack of substances able to promote the Fe and Al leaching • all the substances susceptible to be leached are removed from the profile silice Formazione di caolinite, accumulo di Fe e Al • the weathering process are extremely strong B • represent the highest degree of soil evolution perdita di Si, Ca, Mg, Na, K 44

45

46

47

Lhitic Rodoxeralf A Bt R 48

49

50

51

52

53

54

55