Nature's superhero rock varnish… Are the answers to Mars' unsolved questions hidden in rock varnish?
The beautiful and unique landscapes of Ladakh have attracted the attention of tourists and scientists for decades. The beauty here exudes a distinct quality. The region is a high-altitude desert because the Himalayas block the monsoon. Its arid and extreme climate (characterized by extremely high or low temperatures) challenges the existence of people, flora, and fauna amidst adverse conditions, making this place truly unique. Due to the dry and cold conditions as well as its high altitude, protection from ultraviolet rays is also essential here.
From a scientific perspective, this beautiful region of India holds many secrets within itself, which has consistently attracted the scientific community for study. What's most remarkable about this land is that its landscape can be likened to that of Mars. The study we're going to discuss today is not only valuable for uncovering answers to some of Mars' unsolved questions but also provides insights that could be beneficial for future human life.
Dr. Anupam Sharma (Senior scientists) and Dr. Amritpaal Singh Chaddha, from the Birbal Sahni Institute of Palaeosciences (BSIP) in Lucknow, have successfully uncovered many previously unanswered questions in their study. Dr. Chadda explained that all around the world, in dry and semi-arid areas, one can observe a shiny layer or coating of brown, orange-yellow, or black colors on rocks or rock formations. This layer is known as rock varnish. Their study is centered around rock varnish. Dr. Sharma and Dr. Chaddha chose Ladakh for their research on rock varnish due to its suitability, given the region's adverse climatic conditions and unique landscape.
Dr. Chadda explained that this varnish is a naturally occurring surface rich in manganese (Mn), iron (Fe), and clay minerals. Various types of microorganisms are also observed within the interface between the rock varnish and the underlying rocks. This raises questions: What is the relationship between rock varnish, microorganisms, and host rocks? How does varnish develop? How do microorganisms endure in extreme weather conditions? The study has also unveiled that these microorganisms remain preserved for an extended period. What are the reasons behind this? Dr. Sharma and Dr. Chadda have found answers to all these questions through their research."
He explained that various types of microorganisms and metabolites, such as fatty acids, amides, and alkyl benzenes, are present between the layer and the underlying rocks. In addition to the diverse range of microorganisms, the presence of fungi and cyanobacterial cells has also been observed. The interaction between these elements results in the formation of a thin surface known as rock varnish. Ongoing research aims to understand the types of interactions or factors responsible for the development of microbially induced biological surfaces. Rock varnish creates an ideal environment for the growth of microorganisms on the host rocks and provides them with nutrition. This layer not only shields the rocks from adverse conditions in dry and cold climates but also offers protection from ultraviolet rays.
There is also a probability that the organic elements found within the layer, along with their correlation with the local environment, suggest the potential preservation of ancient organic components. During the study, organic biomarkers and isotopic analysis have been employed to identify the presence of microorganisms. Research has also unveiled that the presence of Manganese (Mn) and Iron (Fe) in the varnish not only offers protection against extreme climate conditions (marked by extremely high or low temperatures in terms of sustaining life) but also shields against ultraviolet rays."
Field photographs of different sample locations (RV-1 to RV-4) with field coordinates and elevation of varnish coated rocks utilized in the current investigation.
Dr. Chadda also revealed that this study encompasses three primary aspects. The first is astrobiological, which involves research related to the search for life beyond Earth. Currently, Ladakh is considered an ideal backdrop to understand the conditions on Mars. The motivation for this research also arises from the possibility that terrestrial rock varnish may serve as an analog, providing similar data to the manganese-rich coatings found on Mars. The presence of varnish on Mars may have been instrumental in predicting the existence of life on the planet because, just as varnish provides protection to microorganisms, microbial processes may also play a significant role in varnish formation."
Regarding the second aspect of the study, Dr. Chadda mentioned that the results were surprising because there was a difference in the nature of surface wettability between the varnish and the underlying rock mass. The host rock's nature was observed to be hydrophilic, meaning it retained water, whereas the varnish exhibited a hydrophobic nature, with no water stagnation observed on it. Research suggests that fungi within microbial groups may produce hydrophobins, which could be a factor contributing to the varnish's hydrophobic nature. It wouldn't be incorrect to liken the varnish's behavior to that of a raincoat.
The third aspect of this study is related to the production of hydrogen energy. An electrochemical process is employed to generate hydrogen energy, involving the splitting and separation of hydrogen and water molecules using an electrocatalyst. This process demands a more effective electrocatalyst. Over the past several years, numerous efforts have been made to develop high-quality electrocatalysts, but success has yet to be achieved. Studies suggest that naturally occurring varnishes containing manganese and iron may serve as superior electrocatalysts.
Dr. Chadda highlighted that the nature of varnish, especially its hydrophobic property, has the potential to revolutionize the paint industry in the future. This is because if the correlation between varnish and microbial communities can provide protection to rocks exposed to adverse conditions like cold, sun, rain, storms, and ultraviolet rays for centuries, then this technology, when applied in paint manufacturing, could offer long-lasting protection to buildings. According to Dr. Chadda, rock varnish is like a superhero, not only connecting us to Mars but also safeguarding rocks and the microorganisms present on them in harsh conditions. In the future, these properties could lead to the production of bio-inspired products, water-resistant materials, and natural ultraviolet protectors for the paint and pigment industries. Moreover, it also serves as an improved electrocatalyst for hydrogen energy production.
By
Parul Datt Saxena
Credit:
Rock Varnish: Nature’s Shield
Amritpal Singh Chaddha,* Anupam Sharma,* Narendra Kumar Singh, Devendra Kumar Patel and G. N. V. Satyanarayana
Cite This: https://doi.org/10.1021/acsearthspacechem.3c00071
http://pubs.acs.org/journal/aesccq