CHEM 321 Fall 2024 Environmental Chemistry Lecture 10 PDF

Environmental Chemistry CHEMISTRY321 Fall 2024 Maryam Izadifard Lecture 10 Soil Chemistry 2  Part I: Introduction Suggested readings: Manahan chapters 9.1-9.3 and 10 CB/MC 4th or 5th edition: Chapter 16 GW Van Loon and SJ Duffy "Environmental Chemistry...

Environmental Chemistry CHEMISTRY321 Fall 2024 Maryam Izadifard Lecture 10 Soil Chemistry 2  Part I: Introduction Suggested readings: Manahan chapters 9.1-9.3 and 10 CB/MC 4th or 5th edition: Chapter 16 GW Van Loon and SJ Duffy "Environmental Chemistry" 3rd ed. Chapters 14, 17-18 https://www.youtube.com/watch?v=mg7XSjcnZQM 3  Objectives Following this unit, you are expected to: be able to describe the composition of soil understand that soil is a 3-phase mixture recognize kaolinite, montmorillonite and, illite (differences) be able to classify soil by its physical properties including particle size, texture (soil triangle), and permeability using the soil texture triangle, determine the texture of this soil understand the general pathways by which rocks get transformed into the soil (physical, chemical & biological weathering) recognize different components of soil organic matter be able to define chemical properties (organic matter, pH, available elements, and cation exchange capacity) understand that colloids have a very large specific surface area and cation exchange capacity define the terms total and available elements, cation exchange capacity, and base saturation 4 Terrestrial environment A terrestrial environment refers to land- based ecosystems, where living organisms (biotic components) interact with non-living (abiotic) factors such as soil, rocks, and air. Terrestrial environments cover 29% of Earth's total surface area, while the remaining 71% 4 soil is of interest is covered by water. smaller particles bigger + SA The land is primarily composed of rocks and soil, collectively known as the geosphere, which constitutes the outer 40 km of Earth's crust. The environmental chemistry of terrestrial ecosystems is primarily focused on the study of soils as the foundation of these environments. smallest size of Clay + soil particles 5  Infographic in Why study of soil is important Soil is: ❑ The link between the air, water, rocks, and organisms ❑ Responsible for many different functions: Carbon and nutrient cycling (GBEC) Agriculture and forestry momut soil complete Y curit Water cycling and quality GBFC with Natural waste decomposition important elements the Home for many organisms (e.g., microbes, insects) We could not survive without these soil functions depth kcm" soil ? ? How it takes to produce Is stil renewable long 4 use ↑ no ↳ 200-400 yrs of weathery is due to soil could be lyr lost in erosion 6 https://www.eoi.es/blogs/imsd/soil-its-not-what-you-know-but-what-you-dont-know/ 6  What is soil? -breaking down or dissolving of rocks and minerals Soil is a product of the weathering of rocks by physical, chemical, and biological processes that produce a medium amenable to the support of plant growth. capable to be acted upon or is susceptible to Four major components of soil (3 phases): phases soil hass 1) Finely divided mineral matter meathy Solid phase - 2) Various levels of organic matter soil saturatedmth 420 ↳ not all soils have 3) Water- Liquid phase unhealthyi but no > gas - liquid soil organic matter I soil Sortransfering 4) Air- Gas phase must have air in · responsible healthy for sonn to be nutrients http://mohammad-syarifudin.blogspot.ca/2010/10/3-phases-in-soil.html Manahan, Figure 10.1. Major aspects of soil structure showing a typical distribution of soil horizons: resting on the parent rock is the C horizon consisting of weathered parent rock, above which is the B horizon or Soil is a three-phase mixture and a complete subsoil. The A horizon or topsoil is the top layer and is the most important description in environmental reactions involves part of the soil where plants are rooted. The inset shows aspects of soil microstructure including solid soil particles, water bound to soil particles, all three phases! The nature and composition of and air spaces. any soil can be significantly affected by inputs Manahan chapters 9.1-9.3 and 10 from human activities! 7  Soil profile: Vertical layering of all soil horizons ↳ looking soil where it has a distinct Horizontal layers pure surface have plants where the rooks organ compound on penetrust top soil 4 have organi matters He transfering small parties by > - top soil material from leaching of to subsol C weathering of rocks primary starts with rocky Each layer of soil is known as a horizon. 3 one it cracks into party 3 bedrock Por of soil + farmers Top soil = soil (healthy Every well developed, undisturbed soil has its own distinctive profile characteristics. 8  Weathering by rain water ↑ mixture] smapaie Rainwater percolates through the soil carrying soluble and colloidal (0.001 – 1.0 μm) material lower into soil → results in development of banded layers or “horizons” location change the type of soil and layency Calgary soil Soil found in the lower level forested areas of the Kananaskis Valley 9  Silicate minerals, most abundant in soil z ppm ppm 8 Oxygen 461,000 23 Vanadium 120 mastone 14 Silicon 282,000 17 Chlorine 145 13 Aluminum 82,300 24 Chromium 102 a man 26 Iron 56,300 37 Rubidium 90 20 Calcium 41,500 28 Nickel 84 11 Sodium 23,600 30 Zinc 70 12 Magnesium 23,300 58 Cerium 66 19 Potassium 20,900 29 Copper 60 22 Titanium 5,650 60 Neodymium 42 1 Hydrogen 1,400 57 Lanthanum 39 15 Phosporus 1,050 39 Yttrium 33 25 Manganese 950 7 Nitrogen 19 9 Fluorine 585 56 Barium 425 6 Carbon 200 38 Strontium 370 16 Sulfur 350 40 Zirconium 165 10 Four major components of soil: attached 1) Finely divided mineral matter (variable in size & composition) ↑ toanother Si Primary (e.g. quartz, feldspar, biotite) Secondary (e.g. silicate clay and iron oxide) 3 when rocks undergo weathering Inorganic matter is mostly silicate minerals (rocks), which have polymeric structures containing O and Si 2) various levels of organic matter (1-6 %) 3) Water higher -y SA + More Heru's 4) Air happening a surface. Why clays are important? Clay particles are much smaller than those of sand and silt, their total surface area per gram is thousands of times larger. Consequently, the most important soil processes occur on the surface of colloidal clay particles 11 Baird, C., Cann, M.C., 2008. Environmental chemistry, 4th ed. W.H. Freeman, New York.  The soil particle size : summary -x > - ↓ 18 < I um XLy Clay X10 2 Mm < Silt - clay minerals in sol 12 Clays (particles) are aluminosilicates some of the most important/ubiquitous minerals are natural water barriers & used as landfill liners constitute large component of soils are important in interaction between inorganics & organics form sheet-like structures Examples of clay minerals: illite, kaolinite, montmorillonite exchange capacity cation : 3 holding into nutrunts and later for plants releasing 13 Clay minerals no penetration ↑ MO thre of payers tetrahedral be layersore stuck together trapezoid shape - Silica sheet eatina > - bed e surfac b) the IS Clay surfun negatively charged : can attract and attain to Octahedral ↳ One type of clay 1 : 2 ratio cations sillion ~ rectangle ratio aluminum : I I : shape : alummum silicon Alumina sheet surface + - recharge clay Silica- Tetrahedron A) kaolinite: Al2Si2O5(OH)4 or Al2O3. 2SiO2. 2H2O Alumina- Octahedron B) Illite: K0-2Al4(Si8-6Al0-2)O20(OH)4 C) Montmorillonite: Al2(OH)2Si4O10 or Al2O3.4SiO2.H2O 14 https://www.kullabs.com/class-engineering/civil-engineering/soil-mechanics/soil-structure-and-clay-materials/soil-structure-and-clay-minerals Clay minerals FYI Silica sheet Alumina sheet Silica- Tetrahedron- T sheet A) kaolinite: Al2Si2O5(OH)4 or Al2O3. 2SiO2. 2H2O Alumina- Octahedron- O sheet B) Illite: K0-2Al4(Si8-6Al0-2)O20(OH)4 C) Montmorillonite: Al2(OH)2Si4O10 or Al2O3.4SiO2.H2O 15 https://www.kullabs.com/class-engineering/civil-engineering/soil-mechanics/soil-structure-and-clay-materials/soil-structure-and-clay-minerals  Model diagram of montmorillonite clay structure colliodal particl + ↑ settle down 3bc of negative charge Crepel each other 16 Adapted from: Pore architecture modulated clays and zeolites as solid acid catalysts for selected organic reactions Clay minerals Kaolinite: One basic layer of Kaolinite consists of a single sheet of silica tetrahedron and a single sheet of alumina octahedron (1:1 minerals). The basic layer is strongly-bound with each other by hydrogen bonds. # IHBanding FYI Meziane et al., JMES, 2017, 8 (10), pp. 3625-3636 Illite: An illite basic layer consists of a sheet of aluminum octahedron sandwiched by two sheets of silica tetrahedron. These basic layers are weakly bound together by K+ ion (exchangeable cation). + Montmorillonite: A basic layer of montmorillonite consists of one aluminum octahedron sandwiched between two sheets of silica tetrahedron (same as illite). Between these layers, water molecules are found which produce very weak bonding. The clay is known for its high susceptibility to swelling and shrinkage. H20 17 https://www.kullabs.com/class-engineering/civil-engineering/soil-mechanics/soil-structure-and-clay-materials/soil-structure-and-clay-minerals More information on montmorillonite Al2(OH)2Si4O10 or Al2O3.4SiO2.H2O full exam Don octahedral tetrahedral some "si andAe replacing instead of 3 positive change charge with Al , Fe. My there is4 positive Sixt →A large amount of negative charge due to the 113 I + > - and thy adds more Alst isomorphous substitution of Al3+ for Si4+ atoms Feat , Myst + negative charge to Fe2+ and Mg2+ for Al 3+ clay isomorphous = having the same crystal form then more cuticy attracted are more The negative residual charge located in the interior of layer, to the Surface are compensated by cations in the interlayer space, which are of soil cluy loosely held at the surface and are exchangeable. → large cation exchange capacity + can bind water + swell → liner in landfills http://pubs.usgs.gov/of/2001/of01- 041/htmldocs/clays/smc.htm 18  Soil formation 4 weathering Product of rocks - ↳ physical , chemical , biological Complex processes by which rocks on earth’s surface are transformed into soils are collectively known as weathering physical chemical biological These processes have been going on for millions of years mineal rocks big primary -> 19 Weathering of soil crack of rocky Hoo in forms At them ice moe wom take up Ice so the craels cruck and Physical (Mechanical- disintegration) Temperature Erosion & deposition by wind, water & ice Plants and animal influence > effects of - erosio and wind Rock Drak into mini particles -> physical S brological proces I create in rock http://schools.bcsd.com/fremont/4th_Sci_earth_slow- and changes.htm plants Wils enter the crel Chemical (decomposition) and push the roels apart different Hydration y Acid- base reactions Hydrolysis Complexation reactions Redox reactions 20 http://www.backyardnature.net/chiapas/rocks.htm  Weathering by hydration Hydration: chemical addition of water molecules to the rocks’ minerals. This is one of the most common processes in nature and works with secondary minerals. Upon hydration, there is swelling and an increase in volume of minerals. The minerals lose their luster and become soft (deformation). structure of into mineral How can get company formation (swollen and y changes instable : Drink apart) mineral under stress easily y breaks apart 21 http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1124303183&topicorder=4&maxto=7 Weathering by acid base reaction (carbonation) Carbon dioxide when dissolved in water it forms carbonic acid. 2H2O + CO2 →H2CO3 This carbonic acid attacks many rocks (limestone) and minerals and brings them into solution. CaCO3 + H2CO3 → Ca(HCO3)2 (Calcite) slightly soluble (Ca bicarbonate) readily soluble discoundry orignal port of rock 22  Weathering by hydrolysis istout revls with minerals Hydrolysis: general term in which water is a reactant plays a major role in the weathering of rocks and minerals example: Orthoclase feldspar (igneous mineral) is hydrolyzed to kaolinite (secondary mineral). avd medium [ 2KAlSi3O8(s) + 2H3O+(aq) + 7H2O(aq) → Al2Si2O5(OH)4(s) + 4H4SiO4(aq) + 2K+(aq) Par 3 primary mineral ↓ silicic acid to mineural unvent Inday clay Score Further hydrolysis converts kaolinite to gibbsite..orgimom] ↳ due to Al2Si2O5(OH)4(s) + 5H2O(aq) → 2Al(OH)3(s) + 2H4SiO4(aq) 3 clay this weathering sequence is important with regards to the abundant rainfall in the tropics - clay like → solubility of silicic acid (150 mg/L) results in the formation of red soils depleted in silica, but rich in kaolinite and aluminum and iron hydroxides. in general: Aluminosilicate + H3O+(aq) + H2O(aq) → clay mineral(s) + H4SiO4(aq) + cation(aq) 23 Manahan, chapter 9.2 Weathering by complexation and redox chemistry inside primary mineral rock Complexation: contributes to weathering: Fe3+ and Al3+ both form insoluble hydroxides in - water, but there is evidence of substantial solubilization in soil → due to the formation of soluble organic complexes (from soil organic matter); more than 90% of the soluble Fe and Al in soil is present in form of organic complexes. organ acid -> act as ligand (Chelates) Oxidation/reduction: when primary minerals containing elements in low oxidation states exposed to atmosphere their oxidation state increases → disturbs charge balance of the mineral → loss or gain of other elements to maintain neutrality → formation of secondary minerals. e.g., oxidation of iron in the primary mineral biotite from Fe2+ to Fe3+ produces the clay mineral vermiculite (another form of clay minerals) and K+ is lost. disturb ↑ enay of equation K2(Mg, Fe(II))6(AlSi3O10)2(OH)4 → Mg0.84(Mg5.05, Fe(III)0.9)(Si2.74Al1.26O10)2(OH)4 + 2kt. ↳ oxidized 1 k is lost from structure 24 Manahan, chapter 9.2  25 https://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3568.html  https://www.emaze.com/@AFOO Biological weathering RWTC/Weathering-&-Eroison Biological weathering is the weakening and subsequent disintegration of rock by plants, animals and microbes. Growing plant roots can exert stress or pressure on rock. Although the process is physical, the pressure is exerted by a biological process (i.e., growing roots). Biological processes can also produce chemical weathering, for example where plant roots or microorganisms produce organic acids which help to dissolve minerals. Microbial activity breaks down rock minerals by altering the rock’s chemical composition, thus making it more susceptible to weathering. One example of microbial activity is lichen; Poymbotic lichen is fungi and algae, living together in a symbiotic relationship. Fungi release chemicals that break down rock minerals; the minerals thus released from rocks are consumed by the O algae. As this process continues, holes and gaps continue to develop on the effect between - rock, exposing the rock further to physical and chemical weathering. forgi algueand Photosynthesis estre sugn Left, circular lichen in Great Falls, MD, and right, a lichen covered rock at Lake Superior. (Images by C. Geiss.) 26 http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1124303183&topicorder=5&maxto=6 Biological weathering Burrowing animals can move rock fragments to the surface, exposing the rock to more intense chemical, physical, and biological processes and so indirectly enhancing the process of rock weathering. https://www.quia.com/jg/2210202list.html 27  Soil properties ❑ Physical ❑ Chemical Size Total elements Texture Organic matter Available elements Permeability CEC https://www.pinterest.com/pin/829999406309916684/ 28 http://karnet.up.wroc.pl/~weber/kwasy2.htm Physical properties 29  Soil properties: Physical properties 1. particle size (ot soil) has good drainage (poor water every soil is made up of particles that have different sizes retention) and is readily aerated → soil can be subdivided into fractions based on the most important components: particle size (there are several classification schemes) primary minerals quartz and feldspars → poor source of nutrients actual soil > - mixture of day , silt , Sund , soils rich in clay gravel are heavy & poor drainage and clay + stuck together aeration : low permeability soil texture > - large particle Y H0 can clay particles act as colloids in water small particly pass thry 4420use best agricultural soil consists of a combination of soil types Baird, C., Cann, M.C., 2008. 30 Environmental chemistry, 4th ed..  understanding good ful D al Clay minerals vs. Clay sized particles/material may be comprised of clay minerals, organic e.g. matter, primary minerals and Fe and Al kaolinite hydroxides. montmorillonite → have large surface area → can retain nutrients 31 Soil properties: Physical properties 2. texture > - mixture of soil components (clay , silt , sand) A collective term that defines a soil by proportion of different particle size components use soil triangle: given exam 100 0 > - * know how to textures Sol find % of soil clay 30% and where the Zero is silty sandy clay clay silty A understand 35% sandy clay clay loam S loam loam loamy sandy silt loam 0 sand sand loam silt 100 100 35% 0 % sand https://cdn.brandfolder.io/4YGXIGTG/at/pypo6z-d6bei8-6ckiaj/Keep_Safe_English.pdf * clay loam report - > - as Example: soil contains 35% clay, 30% silt and 35% sand soil texture ↳ soil texture is loam i day Soils that are desirable for agriculture often fall in the middle region 32 Soil properties: Physical properties ~> exactlygir is find texture of soil goul : % 33 http://soils.usda.gov/education/resources/lessons/texture/textural_tri_hi.jpg  Example 1 given size -> not % of soil A soil sample was found to have particles with a trimodal size distribution. The first mode (30% of the particles) was found to have a median size of 1 μm. The second mode has a median size of 7.5 μm and contains 20% of the particles. The third mode has a median size of 50 μm. Using the soil texture triangle, determine the texture of this soil Gumcy] Summis < , day 30% 20 % silt 50 % sund ? S 100 - 30 - 20 = 50% 34  Soil properties: Physical properties : texture 1 Sandy Clay loam of soil is ⑳ % 35 http://soils.usda.gov/education/resources/lessons/texture/textural_tri_hi.jpg Soil texture determination : Interpretation Rules for points on the lives Two-class line : > if point lies the line between boundary the - on 2 texture classes Lex : between sandy loam and lour) classified the soil is as both types Loum-roum with characteristics ex : Sandy or roam sandy Soil properties: Physical properties 3. permeability > - need pores and pors to be connected = measure of ability of soil to conduct the flow of water after a heavy rain, a permeable soil transports the water rapidly downwards low permeability consequences? → soil can become waterlogged → anaerobic conditions permeability but low can have high porosity , > - DC pores are not attached water can't pass the (not connected) : how well water can pass the http://petroleumandgasengineering.blogspot.ca/2016/01/permeability.html permeability soil -> 36 Chemical properties 37 Soil Chemical Properties: Total Elements z ppm ppm 8 Oxygen 461,000 23 Vanadium 120 must [ 14 Silicon 282,000 17 Chlorine 145 the 13 Aluminum 82,300 24 Chromium 102 26 Iron 56,300 37 Rubidium 90 20 Calcium 41,500 28 Nickel 84 11 Sodium 23,600 30 Zinc 70 12 Magnesium 23,300 58 Cerium 66 19 Potassium 20,900 29 Copper 60 22 Titanium 5,650 60 Neodymium 42 1 Hydrogen 1,400 57 Lanthanum 39 15 Phosporus 1,050 39 Yttrium 33 25 Manganese 950 7 Nitrogen 19 9 Fluorine 585 56 Barium 425 6 Carbon 200 38 Strontium 370 16 Sulfur 350 40 Zirconium 165 38 Soil Chemical Properties: Cation Exchange Capacity (CEC) Soil components such as clay minerals and organic matter have the ability to electrostatically adsorb cations to their surface. CEC (Cation Exchange Capacity): how well soil > - electrostatic attraction can attech to cutions between soil and catters CEC refers to the total amount of cations that a soil can hold. It indicates the soil's capacity to retain and exchange positively charged nutrients (cations). CEC Measurement: CEC is a quantitative assessment of a soil's ability to adsorb or hold cations. It is one of the most measured properties of soils, as it reflects soil fertility and nutrient retention capacity. most important cations: Ca2+, Mg2+, K+ , Na+ hydronium ions H3O+ also important notatO o Depends on Major and what cations are absorbed ex: 10tOK SunA un surface 39 Baird, C., Cann, M.C., 2008. Environmental chemistry, 4th ed. W.H. Freeman, New York.  halk Soil Chemical Properties: Cation Exchange Capacity to > ability of soil to - on > - cutined to # of negative Under acidic conditions, a large portion of the cation exchange sites may be occupied by H3 O+ ions: charge on (a) nutrient binding capacity is diminished and surface (b) reduced ability to neutralize additional acidity (acid rain). Note: in neutral and alkaline soils the contribution of H3O+ is negligible 2+ 2+ + + ↑ CEC Base Saturation = number of exchange sites occupied by Ca +Mg +K +Na ×100% better = what is gooda "How many lange site total number of exchange sites a surface is occupied on surface (occupied by cations) terms Large base saturation value is desirable (soils with low CEC and/or base saturation susceptible to acidification) of ↳ unfrients fr C) plants and buy Sutuntin Ms Depends on : Wide range of CEC values observed: components of soil and location / CEC range (average) CEC Material antimo@ (cmol kg-1) unit fur - S Surface soil (cmol kg-1) highest Kaolinite 3 -15 (8) Kentville sandy loam (Nova Scotia) 10 Montmorillonite 80 – 150 (100) Chlorite 10 – 40 (25) St. Quintin peat (Quebec) 155 Quartz 1 – 2 (2) Baker Lake sand (NWT) 18 Organic matter high (= 150 – 500 (200) 4 Have lotsofNegative - Mechanism of Negira 40 charge production  soil Example 2 Finding CEC in 52 # important has positive ↑ -Marge 10.0 g of soil were shaken with 100.0 mL of O 1 M ammonium acetate, allowed to stand for 2 hours, and filtered. 10.00 mL of the filtrate was taken and found to have mass mixing ratios men & of: : muss ratio actate shake ↳ IM talkmy about ammonium use solution and with soil solutions mass > - ↳ ! cations are released 200 ppm Ca2+, 180 ppm Mg2+, and 270 ppm K+. The concentration of Na+ was below the detection limit. What is the cation exchange capacity (CEC) of the soil (in units of cmol kg-1)? Assume a base - saturation of 100% and a water density of 1.00 g/mL. ↳ whole surface occupied by ions is Analyze for Ca2+ Mg2+, K+ Shake 100 ml 10 ml + water 10 mL of 100 mL 420 of minerals sample the log Find