EPSc 116: Resources of the Earth. Lecture 24 on Ch. 9: Fertilizer and Chemical Minerals. Themes

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1 EPSc 116: Resources of the Earth Lecture 24 on Ch. 9: Fertilizer and Chemical Minerals Themes Look at earth as a source of chemicals, rather than just metals 3 general groups of non-metals: fuels, fertilizer and chemical minerals, building materials Chemical minerals are mostly precipitates from water Form in an aqueous, sedimentary environment Their solubility is important to their use Three elements essential for plant growth: nitrogen, phosphorus, potassium Huge use of mineral-derived fertilizers: good and bad results Halite (table salt) is the most used chemical mineral Many minerals used in foods, supplements, cosmetics, medicines, toothpaste

2 Chemically Precipitated Minerals Chapter 9 deals with a wide range of everyday and "exotic" chemical ppts. Many of the minerals come from same geologic and chemical processes. Water-solubility is a very big issue (1) allows build-up of dissolved constituents and eventual precipitation (2) accounts for the need for fertilizer for plants (3) causes the susceptibility of such precipitates/minerals to leaching Geologically: Basin forms, seawater becomes isolated, water evaporates, brine forms. Saturation is reached, and one or more minerals precipitate Evaporites are sedimentary deposits consisting of layers of individual minerals, i.e., chemical precipitates.

of dissolved ions increases Saturation is reached Nucleation of tiny

3 Development of Evaporite Deposits Evaporation faster than water influx Possible isolation from influx Possible desert environment Concentration of dissolved ions increases Saturation is reached Nucleation of tiny crystals occurs Sequential precipitation of minerals CVS4, Fig Evaporite basin

4 Chemically: seawater becomes increasingly concentrated (brine) and finally reaches saturation. Seawater Evaporation Seawater 1,000,000 grams 1 metric ton (tonne) Cations (Na +, Ca 2+ ) and anions (Cl -, SO 4 2- ) build up; exceed solubility (i.e., no more can dissolve). Sequence of minerals ppt. from evaporating seawater: CaCO 3 CaSO 4 NaCl Mg & K sulfates Mg & K chlorides Much limestone forms/formed this way. NaCl (halite) and CaSO 4 (anhydrite) common 100% % % % CVS4, Fig CVS4, Fig. 9.16

7 Lake Bonneville at night. Photo from National Geographic.

8 Lake Bonneville salt flats used as a speedway for cars and other vehicles.

Fertilizer as Example of Important Chemical Mineral Large tonnages of rock mined for fertilizer Chemically intense processing Strong (+, -) environmental implications of mining, processing,

9 Fertilizer as Example of Important Chemical Mineral Large tonnages of rock mined for fertilizer Chemically intense processing Strong (+, -) environmental implications of mining, processing, and use N, P, K (nitrogen, phosphorus, potassium) are essential plant nutrients Incorporation into essential molecules such as proteins and DNA Act as catalysts to important biochemical reactions

10 Goals of Fertilizer Application Apply nutrients to (poor/depleted) soil in watersoluble form that plant roots can take up. Bioavailability (ability to be drawn into and used by plants) is the issue with fertilizers, bioavailability is essential. Note: with other chemicals, such as toxins, bioavailability is the fear (undesired).

11 N, K, P: Essential Elements for Plants For centuries, we used biological products as fertilizer: manure, guano, dead fish, bones, wood ash. Now have gone back to geological sources. N: not much nitrogen in typical rocks (air has 78%) Natural nitrate (NO 3 ) deposits form from evaporation of water, but nitrate is so water-soluble that minerals typically dissolve away again Manufacture of nitrogen fertilizer from nitrogen (from air) plus methane (natural gas, CH 4 ) K: potassium is a geochemically abundant element Major component in some feldspar (pink mineral in granite) Evaporite minerals, such as KCl P: phosphorus is essential in DNA, ATP, ADP (energy cycles of cells) Often the life-limiting element Bad aspect is eutrophication

http://05lovesgeography.blogspot.com/2011/02 /eutrophication.

12 Eutrophication Entry of too much nutrient material into a lake causes algae to bloom (covering the water and blocking light) and then die (consuming oxygen from the water during their decay). /eutrophication.html Liberty Lake, WA, in the 1970s, while suffering from eutrophication. Algae completely cover the surface.

About 6 wt% phosphorus, 9 wt% nitrogen, 2 wt% potassium, and water Chincha Islands off of Peru.

13 Value of Guano: From the Past to the Present Guano = Valuable bird droppings Found mainly on the coasts and coastal islands of Peru, Chile, West Indies, and Africa. About 6 wt% phosphorus, 9 wt% nitrogen, 2 wt% potassium, and water Chincha Islands off of Peru. Paracas, Peru Guano from bats is considered the best organic fertilizer one can buy. rso/2010/10/04/136756

14 World population Change in world population vs. fertilizer use CVS4, Fig. 9.3 Since 1950, population ~doubled, but fertilizer use increased 10-fold.

15 CVS4, Fig. 9.4 World s largest nitrate deposits are in present-day northern Chile. Extremely arid. Before late 1800s, Peru and Bolivia owned these areas.

16 Marine Evaporite Deposits CVS4, Fig US and Canadian deposits of gypsum and anhydrite (Ca sulfate), halite (NaCl), and potassium salts. The latter mined for fertilizer (K).

17 Major Phosphate Deposits of the United States CVS4, Fig. 9.6 Although ~90% of present phosphate production comes from Florida and N. Carolina, the largest amounts of recoverable phosphate are in Phosphoria Fm.

org/article/phosphate The rocks most commonly mined as phosphate ore are sedimentary phosphorites.

18 Phosphorite Deposits Phosphate [(PO 4 ) 3- ] occurrences: bones, teeth, mineral apatite Ca 5 (PO 4 ) 3 (OH,F,Cl), igneous rocks, sedimentary deposits and rocks. Non-fossiliferous phosphorite, Florida Shark s tooth in phosphorite from Chile. The rocks most commonly mined as phosphate ore are sedimentary phosphorites. Form from the remains of ancient organisms and also chemical precipitation from nutrient-rich upwellings in shallow ocean. Fossil_Shark_Teeth.htm

19 Need Phosphate in More Soluble Form Phosphorite rock requires extensive chemical processing, e.g., Ca 3 (PO 4 ) 2 + 2H 2 SO 4 + 6H 2 O CaH 4 (PO 4 ) 2 + 2H 2 O + 2(CaSO 4 2H 2 O) phosphate rock acid water monocalcium phosphate water gypsum [Production of phosphate fertilizer accounts for huge use of sulfuric acid] Keep processing to get higher concentrations of phosphate in more soluble form.. (atomic substitution) Hitchhiker elements (solid solution): uranium ( wt. % U 3 O 8 ), vanadium, cadmium, selenium occur in natural phosphate deposits. Unfortunately, they can become concentrated in the fertilizer (spread on fields) or in the waste products (as in Florida) from phosphate fertilizer production.

20 CVS4, Table 9.1

Problems with Mining, Processing, and Use of Fertilizer Disruption of huge expanses of coastal/environmentally sensitive land Phosphogypsum stack in

phosphate fertilizer Ca 3 (PO 4 ) 2 + 2H 2 SO 4 + 6H 2 O CaH 4 (PO 4 ) 2 + 2H 2 O + 2(CaSO 4 2H 2 O) fertilizer gypsum Flat-lying phosphate deposits

21 Problems with Mining, Processing, and Use of Fertilizer Disruption of huge expanses of coastal/environmentally sensitive land Phosphogypsum stack in Florida Waste gypsum (phosphogypsum) Uranium release from crushed material Heavy-metal residues in the waste products Eutrophication due to use of phosphate fertilizer Ca 3 (PO 4 ) 2 + 2H 2 SO 4 + 6H 2 O CaH 4 (PO 4 ) 2 + 2H 2 O + 2(CaSO 4 2H 2 O) fertilizer gypsum Flat-lying phosphate deposits in Florida and N. Carolina are mined by mobile drag-lines. Overburden removed, phosphate mined, then land returned to approx. original state. CVS4, Fig. 9.10

Other Chemical Elements/Minerals World and US reserves of chemical elements: very large Sulfur: Vulcanization (toughening) of rubber; H 2 SO 4, chemicals Volcanoes, solfatoras, sulfate

(nuclear wastes), New Mexico Salt: once so valuable that people were paid their salaries in salt Uses: de-icer, chemical industry (Cl 2 gas), food Fluorine: Teflon, toothpaste, HF in industry,

22 Other Chemical Elements/Minerals World and US reserves of chemical elements: very large Sulfur: Vulcanization (toughening) of rubber; H 2 SO 4, chemicals Volcanoes, solfatoras, sulfate sediments, FeS 2 Sulfur captured from coal-fired power plants & petroleum distillation Halite (NaCl): Great Salt Lake; other bedded evaporite deposits; salt domes Waste Isolation Pilot Plant (nuclear wastes), New Mexico Salt: once so valuable that people were paid their salaries in salt Uses: de-icer, chemical industry (Cl 2 gas), food Fluorine: Teflon, toothpaste, HF in industry, flux in steel Fluorite, CaF 2 Sources in U.S. and Mexico Sodium sulfate and sodium carbonate: detergent, paper, baking. Evaporites. At lead-recycling plant, incorporate unwanted sulfur into saleable Na 2 SO 4.

23 CVS4, Table 9.2 part 1

24 CVS4, Table 9.2 part 2

25 Underground Mining for Salt Salt can be mined as solid material or by solution mining, i.e., pumping down steam and retrieving a brine. Salt mine under the former Michigan basin Salt mine under Lake Erie Layers of bedded salt, i.e., sedimentary deposition.

26 Salt Dome Saga Lake Peigneur connects to Gulf of Mexico via a canal. Mine shaft was sunk into the salt dome in Much salt removed since. Many aquifer rock layers have been bent upward by the salt; acts as great oil traps due to salt and shale. CVS4, Fig. 9.B Jefferson Island salt dome, LA, beneath Lake Peigneur Oil drilling began in Accidentally emptied the whole lake into the salt mine below. No casualties.

27 Effects of Salting-Out in Soils Salt-affected soils are visible on rangeland in Colorado. Salts dissolved from the soil accumulate at the soil surface and are deposited on the ground and at the base of the fence post. From Wikipedia

28 Dry Environment of Mined-Out Salt Deposits: Further Use Waste Isolation Pilot Plant near Carlsbad, New Mexico. Former mine in bedded salt. Has accepted nuclear waste for 10 years.

29 Naturally (Geologically) Formed and Deformed Salt Photographed by TA Chris Thom on departmental field trip to eastern Italy along the Adriatic coast

30 Deformation of Ductile, Layered Salt (NaCl = Halite) Photographed by TA Chris Thom on departmental field trip to eastern Italy along the Adriatic coast

Gypsum Caves: Very Rare Naica crystal caves,

31 Gypsum Caves: Very Rare Naica crystal caves, 160 km south of Chihuahua, Mexico Cave of Swords Fluid inclusions in gypsum Garcia-Ruiz, et al. Formation of Natural Gypsum Megacrysts.

32 Actual Minerals Used in Foods and Other Personal Products CVS4, Table 9.3

33 Final Comments on Chemical Minerals World and US reserves of chemical minerals are very large, but the geologic environments that host these materials are often environmentally sensitive. Evaporites are not just the result of, but also a great indicator of, hot dry environments of geologic and climate interest. Remember Wegener. Evaporite minerals found on Mars Occurrence suggests earlier presence of much water on Mars surface Lots of interest, speculation, and new research Environmental impacts of mining, processing, using chemical minerals: Dig up from environmentally sensitive areas (deserts, coasts) Processing: grinding (energy, powders), use of acids, use of much water, chemical residues Solid wastes: gypsum, contaminated by uranium and heavy metals Fertilizer: enters groundwater & runoff, causes eutrophication of water bodies, "salting out" in soils Capture and re-use of phosphate and other nutrients from sewage

35 1884 advertisement for guano

BIOGEOCHEMICAL CYCLES

BIOGEOCHEMICAL CYCLES BASICS Biogeochemical Cycle: The complete path a chemical takes through the four major components, or reservoirs, of Earth s system (atmosphere, lithosphere, hydrosphere and biosphere)