Saturday, January 16, 2010

Geoblog: Piedras en los bolsillos

Reactions:  
0 comments
A good friend mine from Peru working on environmental geology and geologic hazards is running a blog on her research. All posts are related to the research, especially land slides in all their forms, focused in the larger Lima region. Lots of insightful images and maps complement her posts. Take a look at Piedras en los bolsillos which means as much as "Rocks in the pockets". This blog is written exclusively in Spanish.

A new German Geoblog

Reactions:  
2 comments
Gunnar from the Amphibol-Blog has turned my attention to a new, German Geoblog. I am happy to mention it here. The number of German geology related blogs is rather low. The author, a geophysics student, calls him- or herself Stryke and writes exclusively in German on a variety of issues. The name: And the Water seems inviting

Also I added this new blog to my feed of German Geoblogs that you can find on the navigation bar on the right.

Thursday, January 14, 2010

Arsenic, Geology and Public Health

Reactions:  
0 comments
I am by no means an Environmental Geologist nor am I particularly active on the side of Medical or Forensic Geology. Nevertheless I discovered much to my pleasure the fascinating thematical width of geology. Specialising myself in Economic Geology and Carbonate Sedimentology has lead me to consider human health effects of natural rock, soil and water contaminants. In my case arsenic.

Arsenic is a common constituent of metallic ores and used in a variety of applications. However, even in areas that are not mineralised in terms of ores high arsenic values can be encountered. Arsenic poisoning can be acute or chronic. In the geological context acute arsenic poisoning is rather rare and the actual risk lies within chronic arsenic poisoning or arsenocosis. Arsenocosis leads to skin problems, skin cancer, cancer of internal organs, diseases of blood vessels, legs and feet (Black Foot Disease). The most common source of arsenic poisoning is low-level arsenic intake from contaminated drinking water. One of the most severe cases of wide-spread arsenocosis can be found in Eastern India and Bangladesh where groundwater has replaced surface water as the main source of drinking water. Elevated As content now affects millions of people. Even As levels as low as 0,005 - 0,01 mg/l have been found to have negative effects on human health.

Mesozoic limestones in Alsace contain elevated As levels between 20 and 77 ppm. Mineralised faults reach As level as high as 2738 ppm. The global average for limestones is around 2 to 3 ppm. Limestones in southern Alsace function as karst aquifers and are important sources of potable water extracted locally at various springs both natural and artifical. Several studies of the French Bureau de Recherche Géologique et Minière (BRGM) have investigated the As contamination in my thesis area. Groundwater from both natural and artificial springs can contain as much as 5960 µm/l of As. Average values are significantly lower though they still exceed values considered harmless. Studies showed the strong connection to faults and deep, chlorine enriched waters making their way to the surface along them.

The recommendations of the BRGM have, to my knowledge, largely been implemented. Highly contaminated springs have been closed and replaced with springs containing only small amounts of arsenic. The irregular and sometimes unpredictable nature of the karst aquifers causes some springs to be exceptionally contaminated - in connection with local faults. Medium contaminated springs have been recommended to receive water treatment by coagulation to remove As with FeCl3.

In the end these aspects also influence my work. Limestones with elevated As are unsuitable for usage in foodstuffs and animal feeds. However, and I will try to elaborate on this aspect a little in my thesis, with the proven connection to deep seated faults and the studies of the BRGM, it may be possible to delineate areas of limestone with only low As content, which seems to be decreasing rapidly away from major faults and also with decreasing amounts of insoluble residue (Fe- and clay minerals).

Finally, the influence of natural contaminants on human health can be found where one might not expect. Even in projects unrelated to mineralised areas. It has to be considered especially where it seems unlikely to occur - when the groundwater pumps where installed in India and Bangladesh no one considered Arsenic.

References:

Takahiko Yoshida, Hiroshi Yamauchi, Gui Fan Sun, 2004. Chronic health effects in people exposed to arsenic via the drinking water: dose–response relationships in review. Toxicology and Applied Pharmacology. 198 (2004) 243– 252

SANJUAN B., DAESSLE M. (1997) Caractérisation des aquifères contaminés par de l'arsenic dans le Haut-Rhin. Rapport final . Rapport BRGM R39799. Download here.

Friday, January 8, 2010

First news for 2010

Reactions:  
3 comments
Without noticing it on time the two year anniversary of my blog passed yesterday on January 7th. The last two years saw 238 blog posts, with the first year of blogging more active than the 2nd which I blame on being more busy with my thesis related works. I didn't have the opportunity to compile an anniversary post or series, my excuses.

I now have an office at university in which I can work on my thesis. Good that I asked for it because there was just one free room now that one of the interim professors left. Well, till april I can call it my office when I need to move out again for the new teacher but I hope to have more regular writing motivation being at university. I will "move-in" with my stuff sometime next week.

Also I have started in serious searching for possible Jobs or PhD positions related to my main interests of ore and mineral deposits, carbonate sedimentology and phosphorites/industrial minerals exploration. Hopefully, by the time I graduate with my Diplom/Master (probably sometime in May or June) I will have one or two interesting positions to chose from.