NANOGEOSCIENCE: An Introduction
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Transcript of NANOGEOSCIENCE: An Introduction
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Light bulb
After: Hochella Jr. (2008)
Scale in Nanoscience
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Laterite profile, ThenmalaWeathering of Charnockite
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Microcline dissolution
Dissolution of ilmenite,OffshoreDissolution of ilmenite,Offshore
Progressive weathering
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Etch pits:
a. Hypersthene,
B Hornblende
C Augite
D Augite
AJSci,282, Oct.1982
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A S-s Hy
B e-e, Dio
C s-s Aug
D e-e Aug
All etch pits
B AJSci,282, Oct.1982
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AugiteDiopside
Hornblende Hornblende
AJSci,282, Oct.1982
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AugiteHornblende
Clay in Hyp Clay in HbCourtesy: AJSci,282,Oct.1982
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Carbonate cement
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Opy to TalcA,B&C Opy to Talc
D&E Opy to Smectite
AJSci,282, Oct.1982
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OPy to Smectite and Talc AJSci,282, Oct.1982
13Weathering of Opy to amorphous material
AJSci,282, Oct.1982
14Random Aggregation of pyrite, Veli Kayal, Tvm (1992)
15Pyrite framboid, Cretaceous Austin Chalk, Texas, coll. B Woods (Folk, 2005)
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The LycurgusCup- The Roman nano-technology.Tiny amounts of colloidal gold and silver in the glass gives a dichroicproperty- green in day light & red under candlelight.
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vary
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NANOSCIENCE plays out in
the critical zone of the Earth. Jordan (2001) defines in a NRC book entitled Basic
Research Opportunities in Earth Science , as the place where the land meets the fluid
envelopes of the Earth, i.e., the hydrosphere & atmosphere. Fresh water, agriculture & many vital natural resources such as most mineral
deposits & timber are here. Geo & bio aspectsmake it most heterogeneous.
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Based on Physical, geochemical, and biologic processes, four principal & overarching categories identified.
1) biologic2) weathering,
3) fluid transport, &4) near-surface tectonics.
Boundary of Nanogeoscience & life science fuzzy.
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1) Biologic Activity: Due to organism s nutritional
requirements, drives a significant amount of chemical cycling within & between
water, soil, rocks &atmosphere; 2) Weathering:
Constantly at work in the critical zone, generating soil, destroying & producing minerals in the process & redistributing elements among water, rocks, & organic
materials
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3) Fluid transport: the critical component in water
resources supply & management, as well as everything from flooding to
landform development4) Near-surface tectonics:
shapes the land surface through faulting, subsidence, uplift & mass
movement
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Transport of metals & organics in near surface environment;
Global geochemical & climate cycles (+carbon);
Ore genesis & exploitation; soil science; microbial geochemical action; origin of life; space weathering & planetary
surfaces; aerosol transport & ice nucleation; even deep earth processes.
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Nanoscale phenomena involving nano-sized geomaterials-
Processes of elemental distribution; Biologic abiotic Earth interaction; Heterogeneous catalysis; Reaction pathways & mineral growth; Mineral
Transformation & weathering.
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Where are Nanominerals & mineral nanoparticles?
Noticed widely & commonly in atmosphere, oceans, ground &
surface waters & soils.Also in/on most living organisms &
even within proteins like ferritin- iron storing protein in body tissue.
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Why Nanogeoscience?Nutrients limit Oceanic Productivity;
Iron a chief nutrient, reaches ocean as dissolved inorganic and organic
complexes..Nanoparticles of 2 to 20 nm range
has good amount of iron.Oceanic Iron flux via Fe-containing nanoparticles far exceeds riverine
input. Phytoplankton does 50% photosynthesis
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Importance of Nanogeoscience1. Iron in mineral nanoparticles is bioavailable to various species of marine phytoplankton making them more important source of Oceanic iron.
2. Also in toxic-metal transport in Earth s near-surface terrestrial environment - Radionuclide transport by groundwater over several kilometers in short periods of time defies thermodynamics based predictions
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Importance of Nanogeoscience
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Why Nanogeoscience?Contamination of an area of 1600 km2 by
Cu, Zn, As, Pb, and Cd due to 11/2 century of mining - the largest Superfund site - in
western Montana,USA. Metals moved many hundreds of km down
the hydrologic gradient & across floodplains in the Clark Fork River basin.
Carried chiefly by nanominerals and mineral nanoparticles of manganese and iron oxyhydroxides (Hochella et al. 2005).
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Nanogeoscience, Why?Currently mechanical properties much less studied; so impact on working of Earth less
known; so an area of exciting future research in mineralogy.
Natural production of mineral nanoparticles by mechanical grinding associated with earthquake-
generating faults in shallow crust & Earth s surface is known.
Large volumes of mineral fragments of 10 20 nm in size noticed in pulverized rock in fault zones of
up to 100 m width. Suggesting importance of mineral nanoparticles in fault mechanics
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Why Nanogeoscience ?Nanoparticles of high-pressure silicates (e.g., ringwoodite and wadsleyite) may have key role in deep-focus earthquakes (300 700 km depth) in Earth s mantle.
Mineral nanoparticles fill anticracks (planes of weakness that need not dilate to make empty space), in contrast to a normal crack.
As nanoparticles easily move past each other without mechanical shearing of individual grains (like talc) high pressure does not restrict the movement.
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NATURAL AMORPHOUS NANOMATERIALS
Far less known due to:Limited diffraction informationHard to interpret Spectroscopic
measurements Highly variable chemistry and formBut growing recognition of natural
abundance and importance.
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1.Zhu et al. (2006) reported thick amorphous silica-rich (leached from feldspar or from ground water)
layers of nanofilms (10 50 nm) on feldspar surfaces in the Jurassic Navajo Sandstone, Black
Mesa, Arizona, USA.
Weathering rate of K-feldspars is 10E5 times slower under natural conditions than under
similar conditions in weathering experimentsNanofilm study explains difference the rate
weathering in the lab and under nature.
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TL, K feldspar grain-amorphous over layer , 10-50 nm thick; TR, Weathered basalt with clay precursors; BL- Zn sulfide nanoaggregates, Clark fork River bed sediment, Montana (After:Hochella,2008)
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Several year-long leaching experiments:
Amorphous nanofilms on uranium-containing pyrochlore (a calcium
titanate considered for immobilizing fissile elements), slows release of U
(Stubbs et al. 2008). May play a crucial role in dictating
uranium s mobility through the vadose zone
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The Clark Fork riverbed and Floodplains, MoReducing zones of river bed with amorphous, aggregated Zn-sulfide nanoparticles.Their environmental role almost completely unknown a research opportunity.
Amorphous, metal-bearing, naturally occurring nanomaterials still undocumented or completely unknown.
Recent studies showed secondary amorphous silica with toxic heavy metals are relatively common.
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NANO-MATERIALS OUTSIDE EARTH:(
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Chondritic meteorites & Interplanetary Dust Particles.
Diamond nanoparticles of average 2 to 3 nm dia and grains as small as 1 nm
(<150 carbon atoms) in minute quantities.
Nanodiamonds separated by multistepacid digestion process or burning
down the haystack to find the needle .
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Nanopores and Mesopores?
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A vast array of structures & mechanisms symbolize Inorganic nanosystems (+ living
things).Nanoscale physics & chemistry basis of
Nanobiomachines (molecular motors). For better knowledge of inorganic systems and to better appreciate nanogeo and nanobio
interactions.Better perception of
characteristics and behavior of natural nanoscale biological properties.
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Highly confined pores & tubes greatly modify mineral fluid interface reaction
pathways & kinetics compared to reactions at unconfined mineral fluid
interfaces. Such changes affect sorption, desorption and diffusion,
greatly affecting precipitation, weathering & transport phenomena.
(e.g. Hochella and Banfield 1995; Wang et al. 2003).
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Surface charge, cluster growth characteristics, stability & fluid dynamics
principles dictate aggregation/dis-aggregation behavior of natural
nanoparticles in air & water (e.g. Gilbert et al. 2007).
A combination of experiments & modeling will help researchers to infer the characteristics & behavior of the
nano-aggregates.
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The mineral kingdom is more complex than previously thought. Nanogeoscience is at a relatively early stage of development, and
large gaps exist in our knowledge. The next few years and decades will
be an exciting time of new realizations, discovery, and change .
(Hochella JR, 2007)
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TL- High-resolution TEM images of 2 3 nm nanodiamonds recovered from the Murchison meteorite; TR - interplanetary dust particles (After: Hochella Jr, 2008)
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Potential applications of nanoscience
include: ultra-small sensors & devices, including transducers for
force, pressure & chemical compounds; molecular gears,
motors & actuators. Now is the time to plan
for applications & shape the future with
groundbreaking innovations
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62Pyrite Framboids of cube-octahedron crystals
63Pyrite Framboids of octahedron crystals
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66Folk (2003)
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Folk (2003)
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Folk ( 2003)
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Folk (2003)
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