NANOGEOSCIENCE: An Introduction
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Until recently Geologists never realized that many of the processes of mineral formation and weathering are controlled by nanoscience.Implications of Nanogeoscience to geology are still in the backwaters of research. There is an impending need to train younger generation of the geoscientists in Nanogeoscience. With the help of several illustrations such points are elaborated in this power point presentation.
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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