Coal Geology » Geochemistry

Eutrophication of lakes due to phosphate contamination

Editor — Mon, 25 Jul 2011 21:05:27 +0000

Non-contaminated lakes are “aerobic” (oxygenated) and maintain “oligotrophic” (very low levels of nutrients) condition. Limited number algae grow in such lakes due to limited amount of nutrient available to them. Such lakes are also suitable for the fish population and support aerobic microbes. Facultative anaerobic organism cannot survive in such environment.

A facultative anaerobic organism is an organism, usually a bacterium that makes ATP by aerobic respiration if oxygen is present but is also capable of switching to fermentation. In contrast, obligate anaerobes die in the presence of oxygen.

Respitation: Aerobic CH2O + O2 = CO2+ H2O

Phosphate is commonly used as a fertilizer. Phosphate may be added to the lake through sewage, fertilizer and other sources. The excess nutrients stimulate the algal growth in the lake. The algae grow and die that becomes the food source for the aerobes. In such condition, the aerobe population in the lake multiplies exponentially consuming oxygen at a faster rate than it could diffuse through water. This leads to anaerobic condition in the lake. In such situation, facultative anaerobes thrive killing entire fish population of the lake.

Respiration: Anaerobic 2CH2O + SO4-2 = 2HCO3 + H2S

Eutrophication can be human-caused or natural. Untreated sewage effluent and agricultural run-off carrying fertilizers are examples of human-caused eutrophication. However, it also occurs naturally in situations where nutrients accumulate (e.g. depositional environments), or where they flow into systems on an ephemeral basis.

Calculate Hardness of Water using Excel Spreadsheet: Geochemistry Tips

Editor — Mon, 11 Jul 2011 18:44:28 +0000

Hard_water_and_drop

July 11, 2011 (Coal Geology) Hard water is water referes to the alkaline earth ion concentrations. The primary alkaline earth ions are Ca2+ and Mg2+. Calcium usually dominates over magnesium concentration.

Some important Points:

Hard water is generally not harmful to one’s health
pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water. In boilers, the deposits impair the flow of heat into water, reducing the heating efficiency and allowing the metal boiler components to overheat. In a pressurized system, this overheating can lead to failure of the boiler.
Chelation of organics within soap by the alkaline ions is the main reason of concern for hard water. When soap is chelated, it fails to properly react with the water.
Hard water also forms deposits that clog plumbing. These deposits, called “scale”, are composed mainly of calcium carbonate (CaCO₃), magnesium hydroxide (Mg(OH)₂), and calcium sulfate (CaSO₄).[
Calcium and magnesium carbonates tend to be deposited as off-white solids on the surfaces of pipes and the surfaces of heat exchangers. This precipitation (formation of an insoluble solid) is principally caused by thermal decomposition of bi-carbonate ions but also happens to some extent even in the absence of such ions. The resulting build-up of scale restricts the flow of water in pipes.

Measurement Unit: "mg/L as of CaCO3"

How to convern both Ca+2 and Mg+2 concentration to "mg/L as of CaCO3" unit?

Formula for Hardness = {[Ca+2]x(Mol. Wt. of CaCO3/Mol Wt. of Ca+2)} + { [Mg+2]x(Mol. Wt. of CaCO3/Mol Wt. of Mg+2)
= [Ca+2]x(100.08/40.08) + [Mg+2]x(100.08/24.31]

Use the attached excel spreadsheet to Calculate hardness of water.

Hardness of Water Calculation Spreadsheet -CoalGeology.Com

[ReviewAZON asin="0521891485" display="inlinepost"]Hardness Scale (mg/L of CaCO3):
0-60 – Soft Water
61-120 Moderately Hard Water
121-180 Hard Water
>180 Very Hard Water

Hard water is commonly associated with limestone/dolomite rocks such as in Florida.

Sources:
Hardness in water is defined as concentration of multivalent cations. Multivalent cations are cations (positively charged metal complexes) with a charge greater than 1+. They mainly have the charge of 2+. These cations include Ca2+ and Mg2+. These ions enter a water supply by leaching from minerals within an aquifer. Common calcium-containing minerals are calcite and gypsum. A common magnesium mineral is dolomite (which also contains calcium). Rainwater and distilled water are soft, because they also contain few ions.

The following equilibrium reaction describes the dissolving/formation of calcium carbonate scales:

CaCO3 + CO2 + H2O ? Ca2+ + 2HCO3-

Resources:

http://en.wikipedia.org/wiki/Hard_water

The Unified Soil Classification System (USCS): Brief introduction

Editor — Wed, 06 Jul 2011 20:56:13 +0000

If you are prepare for the the ASBOG exam, don’t forget to glance over the The Unified Soil Classification System (USCS).

The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt):

First and/or second letters
Symbol	Definition
G	gravel
S	sand
M	silt
C	clay
O	organic

Second letter
Letter	Definition
P	poorly graded (uniform particle sizes)
W	well graded (diversified particle sizes)
H	high plasticity
L	low plasticity

If the soil has 5–12% by weight of fines passing a #200 sieve (5% < P_#200 < 12%), both grain size distribution and plasticity have a significant effect on the engineering properties of the soil, and dual notation may be used for the group symbol. For example, GW-GM corresponds to “well graded gravel with silt.”

If the soil has more than 15% by weight retained on a #4 sieve (R_#4 > 15%), there is a significant amount of gravel, and the suffix “with gravel” may be added to the group name, but the group symbol does not change. For example, SP-SM with gravel may refer to “poorly graded SAND with silt and gravel.”

Source: http://en.wikipedia.org/wiki/Unified_Soil_Classification_System

Symbol chart

Major divisions			Group symbol	Group name
Coarse grained soils more than 50% retained on No. 200 (0.075 mm) sieve	gravel > 50% of coarse fraction retained on No. 4 (4.75 mm) sieve	clean gravel <5% smaller than #200 Sieve	GW	well graded gravel, fine to coarse gravel
		clean gravel <5% smaller than #200 Sieve	GP	poorly graded gravel
		gravel with >12% fines	GM	silty gravel
		gravel with >12% fines	GC	clayey gravel
	sand ? 50% of coarse fraction passes No.4 sieve	clean sand	SW	well graded sand, fine to coarse sand
		clean sand	SP	poorly-graded sand
		sand with >12% fines	SM	silty sand
		sand with >12% fines	SC	clayey sand
Fine grained soils more than 50% passes No.200 sieve	silt and clay liquid limit < 50	inorganic	ML	silt
		inorganic	CL	clay
		organic	OL	organic silt, organic clay
	silt and clay liquid limit ? 50	inorganic	MH	silt of high plasticity, elastic silt
		inorganic	CH	clay of high plasticity, fat clay
		organic	OH	organic clay, organic silt
Highly organic soils			Pt	peat

Pyroxenes: Review for the ASBOG Exam

Editor — Wed, 06 Jul 2011 18:48:02 +0000

The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks.
They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems.
Pyroxenes have the general formula XY(Si,Al)2O6 (where X represents calcium, sodium, iron+2 and magnesium and more rarely zinc, manganese and lithium and Y represents ions of smaller size, such as chromium, aluminium, iron+3, magnesium, manganese, scandium, titanium, vanadium and even iron+2). Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes.

The upper mantle of Earth is composed mainly of olivine and pyroxene.

Pyroxene Names

The chain silicate structure of the pyroxenes offers much flexibility in the incorporation of various cations and the names of the pyroxene minerals are primarily defined by their chemical composition. Pyroxene minerals are named according to the chemical species occupying the X (or M2) site, the Y (or M1) site, and the tetrahederal T site. Cations in Y (M1) site are closely bound to 6 oxygens in octahedral coordination. Cations in the X (M2) site can be coordinated with 6 to 8 oxygen atoms, depending on the cation size. Twenty mineral names are recognised by the International Mineralogical Association’s Commission on New Minerals and Mineral Names and 105 previously used names have been discarded (Morimoto et al., 1989).

A typical pyroxene has mostly silicon in the tetrahedral site and predominately ions with a charge of +2 in both the X and Y sites, giving the approximate formula XYT₂O₆. The names of the common calcium – iron – magnesium pyroxenes are defined in the ‘pyroxene quadrilateral’ shown in Figure 2. The enstatite-ferrosilite series ([Mg,Fe]SiO₃) contain up to 5 mol.% calcium and exists in three polymorphs, orthorhombic orthoenstatite and protoenstatite and monoclinic clinoenstatite (and the ferrosilite equivalents). Increasing the calcium content prevents the formation of the orthorhombic phases and pigeonite ([Mg,Fe,Ca][Mg,Fe]Si₂O₆) only crystallises in the monoclinic system. There is not complete solid solution in calcium content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol.% are not stable with respect to a pair of exolved crystals. This leads to a miscibility gap between pigeonite and augite compositions. There is an arbitrary separation between augite and the diopside-hedenbergite (CaMgSi₂O₆ – CaFeSi₂O₆) solid solution. The divide is taken at >45 mol.% Ca. As the calcium ion cannot occupy the Y site, pyroxenes with more than 50 mol.% calcium are not possible. A related mineral wollastonite has the formula of the hypothetical calcium end member but important structural differences mean that it is not grouped with the pyroxenes.

Magnesium, calcium and iron are by no means the only cations that can occupy the X and Y sites in the pyroxene structure. A second important series of pyroxene minerals are the sodium-rich pyroxenes, corresponding to nomenclature shown in Figure 3. The inclusion of sodium, which has a charge of +1, into the pyroxene implies the need for a mechanism to make up the “missing” positive charge. In jadeite and aegirine this is added by the inclusion of a +3 cation (aluminium and iron(III) respectively) on the Y site. Sodium pyroxenes with more than 20 mol.% calcium, magnesium or iron(II) components are known as omphacite and aegirine-augite, with 80% or more of these components the pyroxene falls in the quadrilateral shown in figure 2.

Table 1 shows the wide range of other cations that can be accommodated in the pyroxene structure, and indicates the sites that they occupy.

**Table 1:** Order of cation occupation in the pyroxenes
T	Si	Al	Fe³⁺
Y		Al	Fe³⁺	Ti⁴⁺	Cr	V	Ti³⁺	Zr	Sc	Zn	Mg	Fe²⁺	Mn
X											Mg	Fe²⁺	Mn	Li	Ca	Na

In assigning ions to sites the basic rule is to work from left to right in this table first assigning all silicon to the T site then filling the site with remaining aluminium and finally iron(III), extra aluminium or iron can be accommodated in the Y site and bulkier ions on the X site. Not all the resulting mechanisms to achieve charge neutrality follow the sodium example above and there are several alternative schemes:

Coupled substitutions of 1+ and 3+ ions on the X and Y sites respectively. For example Na and Al give the jadeite (NaAlSi₂O₆) composition.
Coupled substitution of a 1+ ion on the X site and a mixture of equal numbers of 2+ and 4+ ions on the Y site. This leads to e.g. NaFe²⁺_0.5Ti⁴⁺_0.5Si₂O₆.
The Tschermak substitution where a 3+ ion occupies the Y site and a T site leading to e.g. CaAlAlSiO₆.

In nature, more than one substitution may be found in the same mineral.

Pyroxene minerals

Clinopyroxenes (monoclinic)
- Aegirine (Sodium Iron Silicate)
- Augite (Calcium Sodium Magnesium Iron Aluminium Silicate)
- Clinoenstatite (Magnesium Silicate)
- Diopside (Calcium Magnesium Silicate, CaMgSi₂O₆)
- Esseneite (Calcium Iron Aluminium Silicate)
- Hedenbergite (Calcium Iron Silicate)
- Jadeite (Sodium Aluminium Silicate)
- Jervisite (Sodium Calcium Iron Scandium Magnesium Silicate)
- Johannsenite (Calcium Manganese Silicate)
- Kanoite (Manganese Magnesium Silicate)
- Kosmochlor (Sodium Chromium Silicate)
- Namansilite (Sodium Manganese Silicate)
- Natalyite (Sodium Vanadium Chromium Silicate)
- Omphacite (Calcium Sodium Magnesium Iron Aluminium Silicate)
- Petedunnite (Calcium Zinc Manganese Iron Magnesium Silicate)
- Pigeonite (Calcium Magnesium Iron Silicate)
- Spodumene (Lithium Aluminium Silicate)
Orthopyroxenes (orthorhombic)
- Hypersthene (Magnesium Iron Silicate)
- Donpeacorite, (MgMn)MgSi₂O₆
- Enstatite, Mg₂Si₂O₆
- Ferrosilite, Fe₂Si₂O₆
- Nchwaningite (Hydrated Manganese Silicate)

Thiobacillus ferrooxidans and Coal Mining: A Faster Way of Producing Acid Mine Drainage

Ankan Basu — Wed, 20 Apr 2011 21:54:11 +0000

April 20, 2011 (Coal Geology) Thiobacillus ferrooxidans (AKA Acidithiobacillus ferrooxidan) is one of the most commonly found bacteria related to coal mining. As coal forms in a reducing environment, sulfide minerals are commonly found in coal deposits – such as pyrite, arsenopyrite etc. The sulfide minerals are oxidized to form sulfate if exposed to oxygen and leads to the formation of sulfuric acid. Thiobacillus ferrooxidans works as a catalyst in the oxidation process and make the sulfide oxidation faster.Oxygen in introduced during both the surface mining method or underground mining of the coal seam. In case of surface mining, a large portion of the overburden strata is also exposed to the environment.

What is Thiobacillus ferrooxidans?

Thiobacillus ferrooxidans is truly the most common type of bacteria in mine waste piles.
Thiobacillus ferrooxidans is acid loving (acidophilic) in nature and increases the rate of pyrite oxidation in mine tailings piles and coal deposits. They prefer a pH of 1.5 to 2.5.
Thiobacillus are strictly aerobic bacteria (lives only in oxygen rich environment). All species of Thiobacillus are respiratory organisms. (Note: Although Thiobacillus is classified as a strictly aerobic organism, anaerobic oxidation has been demonstrated with T. ferrooxidans using elemental sulfur with ferric sulfate. However, elemental sulfur or ferric iron must be present in order for the bacterium to grow.)
Thiobacillus are also “obligate autotrophic organisms”. They require inorganic molecules as an electron donor and inorganic carbon (such as carbon dioxide) as a source. They obtain nutrients by oxidizing iron and sulfur with O2.
Thiobacillus are Gram-negative Proteobacteria. Their life cycle is typical of bacteria, with reproduction by cell fission.
Thiobacillus are colorless, rod-shaped, bacteria with polar flagella. They possess an iron oxidase, which allows them to metabolize metal ions such as ferrous iron: Fe²⁺ + 1/2 O₂ + 2H⁺ –> Fe³⁺ + H₂O
The genus Thiobacillus is “thermophilic” meaning that they prefer temperatures of 45-50 degrees Celsius.
The bacterium is capable of oxidizing iron and inorganic sulfur compounds producing sulfuric acid, which could lead to acid mine drainage. They are also resistant to heavy metal toxicity.

Where do they normally found?

Thiobacillus ferrooxidans is commonly found in pyrite deposits, metabolizing iron and sulfur and producing sulfuric acid.

What is the use of Thiobacillus ferrooxidans in Mining?

Thiobacillus ferrooxidans has been widely used in a mining technique called bioleaching where metals are extracted from their sulfide ores through biological oxidation. The bacteria is used as catalysts in the chemical process

The discovery of T. ferrooxidans also led to the development of “biohydrometallurgy” which deals with all aspects of microbial mediated extraction of metals from minerals or solid wastes and acid mine drainage etc.

Can we use Bioleaching as a remediation technique?

Yes, we can. BacTech’s patented BACOX technology uses naturally occurring bacteria, harmless to both humans and the environment, to oxidize the contained sulphides and separate metal from the difficult-to-process tailings. In the process, toxic elements such as arsenic are stabilized. The tailings created by bioleaching are benign, and zero environmental damage occurs as a result of the process. An added bonus is its ability to recover valuable metals such as gold, silver, cobalt and nickel that remain in the tailings. Bioleaching is an environmental reclamation solution that also creates a profit. (Source: http://www.bactechgreen.com/s/Home.asp)

: Sulfide Oxidation

The diagram above presents the general geochemical concept of sulfate oxidation. The zone above the groundwater table is the aerobic zone, where the Thiobacillus ferrooxidans could thrive eating pyrite. It would be very common to find sulfate minerals above the water table, such as malenterite (FeSO4.7H2O) while sulfide minerals would be stable below the water table (anaerobic environment).

Thiobacillus Ferrooxidans and Acid Mine Formation: Chemical Reactions

Thiobacillus Ferrooxidans could enhance leaching of heavy metals from sulfidic ores under aerobic conditions about 104 fold or more compared with weathering without bacteria.

Oxidation of hydrogen sulfide by Thiobacilli

HS^- + 2O₂ –> S0₄^– + H⁺

Oxidation of elemental Sulfur by Thiobacilli

S° + H₂0 + 1½O₂ à S0₄^– + 2 H⁺

Oxidation of ferrous and ferric iron by T. ferrooxidans

2Fe⁺⁺ + 2H⁺ + ½O₂ —-> 2Fe⁺⁺⁺ + H₂0

2Fe⁺⁺⁺ + 6H₂0 —-> 2Fe(OH)₃ + 6H⁺

2Fe⁺⁺ + 5H₂0 + ½O₂ —-> 2Fe(OH)₃ + 4H⁺

Oxidation of pyrite by T. ferrooxidans

FeS₂ + H₂0 + 3½O₂ à Fe⁺⁺ + 2 SO₄^– + 2 H+

During the oxidation process, H+ ion is generated. So, the growth of the bacteria reduces the pH of the environment, often below 2. The low pH of the solution leaches our easily soluble elements such as iron and other trace elements in the solution leading to metal laden acid mine drainage (AMD) situation.

How to stop the growth of Thiobacilli

Adding lime to the overburden or the mine tailing could easily stop the growth of Thiobacilli as the sulfide leaching bacteria are acidophilic and could not grow in neutral environment. Which also stop the generation of sulfuric acid if proper amount is added to the coal mine rejects. In many cases the overburden material could have high natural alkalinity due to the presence of carbonate minerals and many not need any additional application of carbonates to fight acid mine drainage problems.

Recommendations:

A complete geochemical study of the target coal seam and the overburden material must be performed and included in mine permit. State and Federal recommendations should be followed to meet mining requirements. In the US, Acid Base Accounting (ABA) is the most commonly used test to evaluate nature of the overburden. In general elemental analyses of the overburden rock material and the coal seam are also performed. In many other countries, such as in Australia, it is common to perform other tests like “Net Acid Generation Test” (NAG) and leach tests to evaluate metal leaching potential over time.

Who to contact?

Recommended Geological Consulting Firm: Marshall Miller & Associates (http://www.mma1.com)

MM&A is a diverse consulting and engineering firm headquartered in Bluefield, Virginia, U.S.A., offers a wide spectrum of services to clients in North America, South America, Asia, and Europe. Over its 35-year history, MM&A has evolved into a leader in the mineral resource, environmental, and carbon management industries. The company’s growth is based on a commitment to applying and developing advanced engineering and scientific technologies and maintaining our talented staff of geologists; hydrologists; earth scientists; and mining, petroleum, environmental, and civil engineers.

References:

Article by: Ankan Basu, Geologist/Geochemist, Marshall Miller and Associates.

Enhanced Monitoring of Hexavalent Chromium in Drinking Water: EPA Guideline

Editor — Wed, 12 Jan 2011 22:04:46 +0000

January 12, 2011, WASHINGTON (Coal Geology)– Several weeks ago, EPA Administrator Lisa P. Jackson committed to address hexavalent chromium (also known as chromium-6) in drinking water by issuing guidance to all water systems on how to assess the prevalence of the contaminant. Today, the agency is delivering on that promise and has issued guidance recommending how public water systems might enhance monitoring and sampling programs specifically for hexavalent chromium. The recommendations are in response to emerging scientific evidence that chromium-6 could pose health concerns if consumed over long periods of time.

[ReviewAZON asin="1583215778" display="inlinepost"]“Protecting public health is EPA’s top priority. As we continue to learn more about the potential risks of exposure to chromium-6, we will work closely with states and local officials to ensure the safety of America’s drinking water supply,” said Administrator Jackson. “This action is another step forward in understanding the problem and working towards a solution that is based on the best available science and the law.”

The enhanced monitoring guidance provides recommendations on where the systems should collect samples and how often they should be collected, along with analytical methods for laboratory testing. Systems that perform the enhanced monitoring will be able to better inform their consumers about any presence of chromium-6 in their drinking water, evaluate the degree to which other forms of chromium are transformed into chromium-6, and assess the degree to which existing treatment affects the levels of chromium-6 in drinking water.

EPA currently has a drinking water standard for total chromium, which includes chromium-6, and requires water systems to test for it. Testing is not required to distinguish what percentage of the total chromium is chromium-6 versus other forms such as chromium-3, so EPA’s regulation assumes that the sample is 100 percent chromium-6. This means the current chromium-6 standard has been as protective and precautionary as the science of that time allowed.

: EPA LOGO

EPA’s latest data show that no public water systems are in violation of the standard. However, the science behind chromium-6 is evolving. The agency regularly re-evaluates drinking water standards and, based on new science on chromium-6, has already begun a rigorous and comprehensive review of its health effects. In September 2010, the agency released a draft of the scientific review for public comment. When the human health assessment is finalized in 2011, EPA will carefully review the conclusions and consider all relevant information to determine if a new standard needs to be set. While EPA conducts this important evaluation, the agency believes more information is needed on the presence of chromium-6 in drinking water. For that reason, EPA is providing guidance to all public water systems and encouraging them to consider how they may enhance their monitoring for chromium-6.

More information on the new guidance to drinking water systems: http://water.epa.gov/drink/info/chromium/guidance.cfm

More information on chromium:
http://water.epa.gov/drink/info/chromium/index.cfm

More information on the status of the ongoing risk assessment:
http://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=221433

Lower IQ in Children could be caused by Fluoride in Water

Editor — Mon, 27 Dec 2010 14:43:14 +0000

NEW YORK, Dec. 27, 2010 (Coal Geology) — Exposure to fluoride may lower children’s intelligence says a study pre-published in Environmental Health Perspectives, a publication of the National Institute of Environmental Health Sciences (online December 17, 2010).

Fluoride is added to 70% of U.S. public drinking water supplies.

According to Paul Connett, Ph.D., director of the Fluoride Action Network, “This is the 24th study that has found this association, but this study is stronger than the rest because the authors have controlled for key confounding variables and in addition to correlating lowered IQ with levels of fluoride in the water, the authors found a correlation between lowered IQ and fluoride levels in children’s blood. This brings us closer to a cause and effect relationship between fluoride exposure and brain damage in children.”

“What is also striking is that the levels of the fluoride in the community where the lowered IQs were recorded were lower than the EPA’s so-called ‘safe’ drinking water standard for fluoride of 4 ppm and far too close for comfort to the levels used in artificial fluoridation programs (0.7 – 1.2 ppm),” says Connett.

In this study, 512 children aged 8-13 years in two Chinese villages were studied and tested – Wamaio with an average of 2.47 mg/L water fluoride (range 0.57-4.50 mg/L) and Xinhuai averaging 0.36 mg/L (range 0.18-0.76 mg/L).

The authors eliminated both lead exposure and iodine deficiency as possible causes for the lowered IQs. They also excluded any children who had a history of brain disease or head injury and none drank brick tea, known to contain high fluoride levels. Neither village is exposed to fluoride pollution from burning coal or other industrial sources.

About 28% of the children in the low-fluoride area scored as bright, normal or higher intelligence compared to only 8% in the “high” fluoride area of Wamaio.

In the high-fluoride city, 15% had scores indicating mental retardation and only 6% in the low-fluoride city.

The study authors write: “In this study we found a significant dose-response relation between fluoride level in serum and children’s IQ.”

In addition to this study, and the 23 other IQ studies, there have been over 100 animal studies linking fluoride to brain damage (all the IQ and animal brain studies are listed in Appendix 1 in The Case Against Fluoride available online at http://fluoridealert.org/caseagainstfluoride.appendices.html).

One of the earliest animal studies of fluoride’s impact on the brain was published in the U.S. This study by Mullenix et. al (1995) led to the firing of the lead author by the Forsyth Dental Center. “This sent a clear message to other researchers in the U.S. that it was not good for their careers to look into the health effects of fluoride – particularly on the brain,” says Connett.

Connett adds, “The result is that while the issue of fluoride’s impact on IQ is being aggressively pursued around the world, practically no work has been done in the U.S. or other fluoridating countries to repeat their findings. Sadly, health agencies in fluoridated countries seem to be more intent on protecting the fluoridation program than protecting children’s brains.”

When the National Research Council of the National Academies reviewed this topic in their 507-page report “Fluoride in Drinking Water: A Review of EPA’s Standards” published in 2006, only 5 of the 24 IQ studies were available in English. Even so the panel found the link between fluoride exposure and lowered IQ both consistent and “plausible.”

According to Tara Blank, Ph.D., the Science and Health Officer for the Fluoride Action Network, “This should be the study that finally ends water fluoridation. Millions of American children are being exposed unnecessarily to this neurotoxin on a daily basis. Who in their right minds would risk lowering their child’s intelligence in order to reduce a small amount of tooth decay, for which the evidence is very weak.” (see The Case Against Fluoride, Chelsea Green, October 2010 )

This company’s web site http://www.fluoridealert.org/

Aluminum Geochemistry Eh-pH, pe-pH diagrams and Solubility

Editor — Sat, 23 Oct 2010 00:58:17 +0000

The Eh-pH diagram for Aluminum in Al-O-OH system is constructed using Al activity as 1E-10. The Aluminum species can dissolve in water in both high and low pH as Aluminum can form complex ions with hydroxide ion (ano with other anions such as SO4). Eh–pH diagram is any of a class of diagrams that designates the fields of stability of mineral or chemical species in terms of the activity of hydrogen ions (pH) and the activity of electrons (Eh). All of the reactions illustrated on Eh–pH diagrams involve either proton transfer (e.g., hydrolysis) or electron transfer (oxidation or reduction) or both.

As we increase the pH of the solution, the fallowing reactions take place:

Al+++ + H2O = AlOH++ + H+
Al+++ + 2 H2O = Al(OH)2+ + 2 H+
Al+++ + 4 H2O = Al(OH)4- + 4 H+

Al Eh-pH Diagram - Al-O-OH System

Al pe-pH Diagram: Al concentration=1E-10 ppm

For Al solubility, we have considered the following special available on Geochemist Workbench program

Diagram for Al+++
Al+++           Al(OH)2+        Al(OH)3         Al(OH)4-
Al13O4(OH)24(7+) Al2(OH)2++++    Al3(OH)4(5+)    AlOH++
Boehmite        Corundum        Diaspore        Gibbsite

Question to ask: If Al is so soluble according to the Eh-pH diagram, how can we have utensils made up of Al?
Aluminum metal rapidly reacts with oxygen and develops a thin layer of aluminum oxide at the surface that prevents the metal from reacting with water.

Alkalinity has no effect on Aluminum solubility. Lime application may stop the iron problem, but is incapable of solving the Aluminum solubility.

Facts about Aluminum:

Aluminum is the most abundant metal in the Earth’s crust, and the third most abundant element, after oxygen and silicon.
It makes up about 8% by weight of the Earth’s solid surface.
Aluminium is too reactive chemically to occur in nature as a free metal. Instead, it is found combined in over 270 different minerals.
Although aluminium is an extremely common and widespread element, the common aluminium minerals are not economic sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3-2x).
Because of its strong affinity to oxygen, however, it is almost never found in the elemental state; instead it is found in oxides or silicates.
Feldspars, the most common group of minerals in the Earth’s crust, are aluminosilicates.
Impurities in Al2O3, such as chromium or cobalt yield the gemstones ruby and sapphire, respectively.
Pure Al2O3, known as corundum, is one of the hardest materials known.

Mining:
Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions.Large deposits of bauxite occur in Australia, Brazil, Guinea and Jamaica but the primary mining areas for the ore are in Ghana, Indonesia, Jamaica, Russia and Surinam.Smelting of the ore mainly occurs in Australia, Brazil, Canada, Norway, Russia and the United States. Because smelting is an energy-intensive process, regions with excess natural gas supplies (such as the United Arab Emirates) are becoming aluminium refiners.

Some example Aluminum reactions forming complex ions.

Al+++ + 2 H2O = Al(OH)2+ + 2 H+

Polynomial fit:
log K = -11.67 + .07537 × T – .0004644 × T^2 + 1.745e-6 × T^3 – 2.394e-9 × T^4