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Fri Jun 15, 2018, 10:51 PM

Large-Scale Uranium Contamination of Groundwater Resources in India.

The paper to which I will refer has the same title as this post, and is published in the current issue of rapid communications environmental journal published by the American Chemical Society. It is this one: Large-Scale Uranium Contamination of Groundwater Resources in India (Vengosh et al Environ. Sci. Technol. Lett., 2018, 5 (6), pp 341–347.

Some text from the introduction to the paper:

India, the world’s second most populous country, extracts more than a third of worldwide groundwater resources, more than 90% of which is used for irrigation.1 Intense abstraction has led to severe groundwater table declines in many parts of the country, especially in the northwestern Indian states of Punjab, Haryana, and Rajasthan.2−5 In 2013, the Indian Central Groundwater Board estimated that groundwater in the majority (66−70%) of blocks (Indian administrative division above village) in these three states was either critically exploited or overexploited.5 At the same time, parts of northwestern India that import surface water through canals are dealing with water logging issues, even in arid, previously groundwater-deficient areas.2,4−6 Overexploitation of groundwater and the use of imported surface water, combined with reported changes in precipitation patterns induced by climate change, have raised concerns about future water sustainability in India,2−4 yet water quality issues are perhaps even more pressing. High concentrations of salinity, fluoride, and nitrate are widespread in groundwater resources throughout the country.6−8 Groundwater arsenic problems have been reported in the delta aquifers of West Bengal and Bangladesh, as well as along the Indo- Gangetic Basin aquifer in Pakistan.2,9 There are also reports of high levels of uranium in groundwater, particularly in northwestern India, which is the focus of this study.

Uranium’s threat to human health comes from its chemical rather than it's radiological properties. Epidemiological and toxicological studies have examined the link between the prevalence of uranium in water and chronic kidney disease (CKD) and demonstrated that exposure to uranium through drinking water is associated with nephrotoxic effects.10-12

The authors produce a map as a graphic to show where the problem is worst:

The caption:

Figure 1. (A) Distribution of major geological formations in India that compose local aquifers, combined with identified districts in India where uranium in groundwater has been reported to exceed (red zone) or not to exceed (blue zone) the World Health Organization provisional drinking water guideline value of 30 μg/L. (B) Distribution of uranium concentrations in groundwater collected in this study, together with the major geological formations and identified districts in Rajasthan and Gujarat, where uranium content in groundwater has been reported to exceed (red zone) or not to exceed (blue zone) 30 μg/L.

30 μg/L is the cutoff in the World Health Organization's provisional guideline for uranium concentrations in drinking water which is or was the equivalent standard at the EPA, at least before it was taken over a corrupt politician who hates science, scientists and the environment and is treating that organization as a personal bank for corrupt politicians who hate science, scientists and the environment.

Note that the authors attach this situation to geological formations, and that this situation is not involved with uranium mining but with the apparent occurrence of uranium ores through which the drinking water percolates.

This does not, however, imply that human activities have no connection to this situation, which the authors note.

The ocean contains about 5 billion tons of uranium, albeit in considerably lower concentrations than is found in the water supplies studied here. If we take the density of seawater to be 1030 kg/m^3, the figures given in this paper, which I pulled up more or less at random from such papers in my files Chemical Geology Volume 190, Issues 1–4, 30 October 2002, Pages 45-67, we can calculate that the concentration of uranium in seawater is about an order of magnitude lower, 3.4 μg/L. Many scientific publications give a figure close to this, with minor fluctuations owing to fluctuations in the density of seawater, which is not constant in all places.

Despite all of the talk from people who hate nuclear energy because they know nothing at all about the subject, who have appealed to "peak uranium" to claim that nuclear energy is not sustainable, uranium is not exhaustible, and no human technology can ever consume it.

It is easy to show that if world per capita average power consumption doubled to around 5000W, (which is still half of the average power consumption of an "average" American), that a person living for 100 years would consume about 100 grams of uranium (converted to plutonium) in their entire lifetime. An appreciation of how much uranium has already been mined shows that the quantity is sufficient to supply 100% of humanity's energy consumption for several centuries, even without the greater quantities of thorium that have been mined and dumped as a side product of the lanthanide industry that supports our stupid, environmentally unacceptable and useless wind industry, among other industries.

The recovery of oceanic uranium for use in nuclear reactors has been under study for more than half a century and the technology is well understood. Because uranium is so cheap from terrestrial ores (and would be even cheaper were we to do away with the stupid practice of dumping so called "depleted uranium" ) the cost of recovering uranium from seawater is not justified as of yet, but since in terms of cost per unit of energy provided, the cost of uranium is trivial with respect to the cost of nuclear energy. Like the cost of the useless and failed solar energy industry, the cost of fuel doesn't matter all that much; it's the device that counts.

If at some point stupid people stop ruling the world, and thus the world energy supply goes nuclear, several hundred years from now, people might be inclined to obtain their uranium from seawater, which is possible because of the extremely high energy density of uranium. (Since it is this factor, the energy to mass ratio, is the most important in determining the environmental impact of a form of energy and its economic viability and sustainability, it follows that nuclear fission is the cleanest form of energy possible, unless of course, as had yet to happen, a viable fusion energy device is made to work.) But one might argue that doing this, obtaining uranium from seawater, one could drain the seas of its uranium.

This however is not possible, because the uranium in seawater is actually a tiny fraction of the uranium on the planet as a whole and in fact represents a small part of a natural uranium cycle.

This brings me back to India.

Most people who have studied nuclear issues and nuclear policy - this excludes 99% of nuclear energy opponents, the overwhelming majority of whom argue from ignorance - will understand that the Indian nuclear energy program is geared to utilizing India's large thorium reserves, primarily because India has very few reserves of terrestrial ores of uranium that can be recovered at current low prices. For this reason the majority of nuclear reactors in India are heavy water reactors, which are suitable for breeding U-233 from thorium. However the solubility of thorium is rather low in most aqueous systems (although this is not the case for its radioactive decay daughters). This means that if one considers eternity a thorium/uranium cycle is not sustainable but a uranium/plutonium cycle is.

Since uranium is not present in Indian ores, they have actually built a pilot plant to extract uranium from seawater. Here's a picture of it:

(Source: Linfeng Rao, LBNL Paper LBNL-4034E (2010))

In a blog post elsewhere, I examined the uranium cycle in some detail and using one of the references I supplied therein, among many others, U-Th-Ra Fractionation During Weathering and River Transport (Chabuax et al, Reviews in Mineralogy and Geochemistry (2003) 52 (1): 533-576) A nice table in the paper gives the quantities of uranium transported by rivers to the sea from the weathering of rocks. Three of the top five are major rivers in India: They are the Indus, the Ganges, and the Brahmaputra rivers, with the other two in the top five being the Mississippi and the Yangtze.

Sustaining the Wind, Part 3, Is Uranium Exhaustible?

Now let's return to the paper cited in the beginning of this post.

The authors note that the mobilization of uranium into the ground water is only possible if two conditions are met. One is the presence of carbonate, because in the ocean and in any other aqueous system this solubility is tied to the carbonate complex. The other is the presence of an oxidizing agent, since the carbonate complex of uranium (VI) is soluble, and the same complex of uranium (IV), the other common oxidation state in terrestrial uranium ores is not.

They write:

Controls on the Occurrence of Uranium. Bicarbonate complexation and oxidizing conditions are two of the most important chemical factors controlling uranium concentrations in groundwater20,25,26,32−34 and appear to be the key factors for the alluvial aquifers in northwestern India. The accumulation of bicarbonate in groundwater enhances the formation of highly soluble uranyl carbonate complexes, which results in elevated uranium concentrations in groundwater. This process is evidenced by the correlation between bicarbonate and uranium in groundwater from most of the aquifers in Rajasthan and Gujarat (Figure 2B and Table S6). This is consistent with speciation modeling conducted with PHREEQC, which predicted that uranyl carbonate species, especially ternary complexes with Ca, are the predominant uranium complexes in groundwater from the alluvium aquifers (Table S7).

Additionally, previous studies have observed massive groundwater table declines in many areas in the unconfined alluvial aquifers of northwestern India.5 This hydrogeological condition likely promotes oxic conditions, which favor the occurrence of uranium as a soluble complex and migration into deeper parts of the aquifer. Although neither oxidation−reduction potential nor dissolved oxygen concentration was directly measured, relatively low concentrations of both iron and manganese and high nitrate concentrations further support our hypothesis of oxidizing conditions in the shallow U-rich groundwater (Table S2).

They note that the conditions under which the uranium is mobilized are obtained by the percolation of water through agricultural fields, particularly because of the accumulation of nitrate, as well as the effect of cycling water through the air, which is increasingly concentrated with the dangerous fossil fuel waste carbon dioxide while we all wait, like Godot, for the grand so called "renewable energy" fantasy to become reality.

They have a nice graphic discussing carbonate and uranium fluxes in drinking and agricultural water:

The caption:

Figure 2. (A) Box plots of uranium concentrations of groundwater from different aquifers in Rajasthan and Gujarat investigated in this study. Red lines represent the WHO’s provisional guideline values for uranium in drinking water. For statistical analysis of the differences in U distribution by aquifer, see Table S4. (B) Uranium vs bicarbonate concentrations in groundwater sorted by aquifer lithology. See Table S6 for Spearman correlations sorted by aquifer.

That the source of the uranium derives from naturally occurring rocks and not from human industrial nuclear practice is indicated by the U234/U238 ratio since U234, always in equilibrium with U238 is mobilized by the recoil of alpha decay. A graphic on that point:

The caption:

Figure 3. 234U/238U activity ratios vs uranium concentration in groundwater from the alluvial aquifers in Rajasthan and Gujarat. The blue line represents secular equilibrium in which the 234U/238U activity ratio is ∼1. 234U/238U activity ratios of >1 observed in most of the investigated groundwater indicate selective 234U chemical mobilization and/or physical recoil from the aquifer rocks.

I believe that the value of "1" here refers to the normal secular equilibrium conditions, and not the actual ratio between U234 and U238.

I have written here that the extraction of uranium from seawater is not economically justifiable, and I certainly consider that the nuclear enterprise in a rational world as opposed to the one in we actually live would be powered essentially by so called "depleted uranium" with a little thorium thrown in to keep up supplies of neptunium to void nuclear weapons proliferation issues.

But the question is whether there is a moral and health reason to do it beyond the cost of ores.

Suppose the Indian government decided to purify the groundwater to remove the uranium it extracts from geological formations. Perhaps some of the cost might well be defrayed by selling or utilizing the uranium so recovered. There is no good reason that any of the many systems known to extract uranium from dilute solutions could not be used to remove uranium from drinking and agricultural water instead of seawater. And indeed, the higher concentrations in this water when compared to seawater would make the economics less onerous.

It's worth a shot.

Later, maybe this weekend, I hope to write a post, in response to an excellent question in one of my earlier posts here, to cover the "external costs" of dangerous natural gas, which will show despite common parlance, including much of it by idiotic anti-nukes who claim as evidence of their stupidity that "nuclear energy is not competitive," that natural gas is not cheap since it incurs a health and environmental cost that will fall mostly on future generations, who will have derived none of the benefits of the "cheap" natural gas now being burned in a sybaritic fashion by people with no concern whatsoever about the future.

The authors of the paper from which this post takes its title specifically mention climate change as a factor in the situation with respect to uranium in Indian drinking water. Of course, I assume that every time the words "uranium contamination" appear, the usual anti-nukes perk up their selectively attentive ears to find another insipid "argument" to criticize the nuclear industry. But to whom does the "external cost" of the uranium in Indian water actually accrue? Could it be that some of the moral responsibility lies with those who either deny climate change or propose silly failed schemes to address it?

I pose this question as I finish up by wishing you a very pleasant weekend, a pleasant "Father's Day," if you are involved in some way with a father.

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