Study Suggests Barium Directly Drains From Fractured Rock

Barium plays a significant role in the current research being done at the Dartmouth College. The researchers are trying to shed some light on the initial chemical reactions found in the organic sediments, which would later be identified as the Marcellus Shale, the main source of petroleum and natural gas. With findings already published in the journal Geochimica et Cosmochimica Acta, the study aims to further an earlier research by the Dartmouth team.

Remarkable high concentrations of toxic metal barium and unusually high total-dissolved-solids were formed when water was injected into the shale structures in hydraulic fracturing. The hazardous wastewater is believed to be partially due to the chemicals found in the injected fresh water when it combines with the highly saline brine, which is normally present in the rock. However, in the earlier research, it was discovered that the chemical reactions between the fractured shale and the injected fresh water enabled the barium to directly drain from the fractured rock, Science Codex reported.

In the new study, barium becomes the point of interest, as the researchers tried to look into why, how and when the Marcellus Shale became enriched with the reactive metal. They examined in detail the mineralogy, chemistry and the sulfur isotope composition of the core, which they consider as a special sample since it has 5,000 micrograms of barium each gram of  rock.

The samples gave the researchers with ideas into when, where and how the barium with mineral changed into iron sulfide while organic rich marine sediment transforms into shale  during Devonian times. In addition to this, the researchers also found barite grains being "bitten" by the pyrite as the latter took the former's place through a complicated set of reactions, which could only happen at a certain depth interval wherein sulfide and sulfate exist. 

Barium mobilization's generalized nature has been well identified, as the new study was able to provide enough ideas, which were better established as barite is broken down in organic rich sediments and in its redistribution in clay minerals, according to SCPR.