On 24th January, 2020, the students of class XI and class XII of Mushtifund Aryaan Higher Secondary School (MAHSS) had the opportunity to interact with and gain invaluable knowledge from Dr. S. Wajih A. Naqvi on the Evolution of the Earth and its Oceans. On behalf of the students of MAHSS I would like to thank our Director, Mr Vyankatesh Prabhudesai, for providing us with this opportunityto interact with such an imminent personality.
Dr. Naqvi did his Master’s Degree in Physical Chemistry from Lucknow University and joined NIO, Goa as a research fellow and received his PhD degree subsequently from Pune University.In the meantime he got a regular position at NIO where he worked until his superannuation in 2016. He was one of the most popular directors at NIO and was very much approachable during his tenure as director. Thereafter he was associated with the Kuwait Institute for Scientific Research for one year before getting reemployed by CSIR as a distinguished scientist for three more years. Presently he is a distinguished visiting director in the department Earth sciences at IIT Kanpur. While at NIO,Dr. Naqvi visited abroad with several prestigious fellowships, to carry out research at Columbia University, USA, Nagoya University, Japan, and Leibniz Centre for Tropical Marine Research and Max Planck Institute for Marine Microbiology, Germany.The primary focus of Dr. Naqvi’s research has been recycling of polyvalent elements, mainly anoxic aquatic environments in the sea as well as freshwater systems such as lakes reservoirs and groundwater.
Dr. Naqvi has received many awards including CSIR Young Scientist Award, the prestigious Bhatnagar Prize,Vigyan Ratna Samman from UP Gov., National Award for Ocean Science and Technology and National Geo Science Award for Excellence. He is a fellow of all the three national Science academies in India and presently serves as a member of INSS council. He is also a fellow of The World Academy of Sciences and a Geochemistry fellow jointly selected by the Geochemical Society of USA and the European Association of Geochemistry. Dr. Naqvi has published over 200 research papers in top rated journals and is one of the most cited geoscientists in the world.
The topic Dr. Naqvi explored in the session was “Formation and Evolution of our Planet & its Oceans”.
Dr. Naqvi began by comparing the atmosphere of the Earth to that of its neighbouring planets, Venus and Mars.He pointed out that the CO2 was the major gas in the atmospheres of both Mars and Venus while on our planet it is present in traces. He mentioned here that the original CO2 content in Earth ‘s atmosphere was originally 0.028 % but has now risen to 0.0412 % today which is very concerning as it increases global warming. He mentioned that on the on the other hand the Earth ‘s atmosphere contained a lot of Nitrogen(78%) and a lot of oxygen (21%) , which, Dr. Naqvi mentioned, is very rare as it is not present in such high quantities in the celestial bodies we know of and hence makes our planet special .
Dr. Naqvi then explained that the most unique feature of the Earth was the fact that it sustains life. He then mentioned the factors which allow life to exist on Earth-the Right Size, the Right Distance form the Sun, and the Right Chemical Composition-in depth.
Dr. Naqvi then mentioned that the Earth is the Only known celestial body known to contain Liquid water on its surface. He then explained the Habitable Zone which is the region around a star where water can exist in liquid form on the surface of an orbiting planet. He said the key word here was “ON THE SURFACE”as there are other celestial bodies, such as the moons of Jupiter which have water but it is present below the surface rather than on the surface and yet do not have life.He then said that the Earth is not the only body located within the habitable zone of the Sun. Our own moon and Mars are also present in the habitable zone. However, the reason the moon and Mars don’t have life is because they are much smaller than the Earth.
Dr. Naqvi then compared the Chemical composition of the Earth’s layers to the Milky Way Galaxy-our home galaxy- as the Right Chemical Composition is one of the reasons for life on earth.He pointed out that the composition of our planet was quite different form that of our galaxy. While helium(73.9%) and hydrogen(24%) were present in high quantities in the milky way galaxy they were present in trace quantities on the earth.On the other hand, oxygen content in the milky way was quite small while on Earth oxygen is the second most abundant element. Dr. Naqvi then pointed out that iron was the most abundant element on earth while it was present in low quantities in the milky way galaxy.The earth has high abundance of heavy elements while they are present in very low quantities in the milky way.
Dr. Naqvi then went on to explain the reason for this composition of chemicals.For this he explained the origin of the solar system. Dr. Naqvi said that the solar system originated 4.6 billion years ago. Prior to the creation of the solar system there was a huge cloud of dust and matter called the solar nebula. For reasons that are not quite clear, this cloud collapsed into itself in the form of a disk which spun very fast. At the centre of the disk was the Sun which swallowed nearly 99% of the mass of the solar nebula. As a result, the Sun became massive and imploded into itself which made it so dense that there was fusion of hydrogen atoms into heliumatoms through nuclear fusion. Whatever was remaining in the gas formed the planets. The heavy elements stayed close to the sun and formed the rocky planets while the lighter elements moved further away from the sun and formed the gas giants or icy giants. Dr. Naqvi compared this to the process of winnowing.
Dr. Naqvi then explained the differentiation of the planet Earth. It is divided into three layers- a thin, outer crust, a rocky intermediate mantle and an inner molten core. The heavier metals were found deeper inside the earth.Due to its molten iron-nickel core the earth acts as a huge dipole magnet and has a region called magnetosphere around itself which protects it form solar wind. Otherwise Earths atmosphere would be blown away as it happened with Mars whose core cooled down rapidly due to its small size.Without the magnetosphere the oceans and atmosphere would be blown.Hence, we owe our existence to the magnetosphere which is itself present due to the Right Size of the Earth.
Dr. Naqvithen went on to explain the origin of the oceans which is actually not very clear.There are some theories about it, though. The solar nebula is expected to have contained water. Degassing from molten material released volatiles including water. Additional sources of water could be asteroids, comets which bombarded the earth when it was young. As the earth cooled, water condensed, forming the oceans.
Dr. Naqvithen went on to explain how the oceans sequestered CO2 from the atmosphere. CO2 is highly soluble in water and absorption of CO2 by water was the main method of removal of CO2 form the atmosphere. Most of these caron in our planet is locked in carbonate rocks making the earth habitable. These carbonate deposits are actually biogenic(corals for example. which have a calcium carbonate shell).
Dr. Naqvithen explained the evolution of oxygen on earth. In the first two billion years after earths formation there was no free oxygen. About 3.4 billion years ago (Ga) anoxygenic phototrophs evolved which used H2S in place of H2O along with CO2 to form organic matter water and Sulphide.But around 2.7 Ga oxygenic phototrophs evolved. Increase in O2 levels triggered the Great Oxidation Event around 2.4 Ga. Accumulation of O2 after 0.85 Ga promoted biodiversity and created suitable conditions for evolution of higher life forms. TheGenus homo appeared only about 3 million years ago but managed to ruin the planet earth’s system including deoxygenation of the seawater.
Dr. Naqvithen explained in depth the deoxygenation of the seawater. He showed us a graph showing the distribution of oxygen along a vertical section in the Indian ocean.The deep ocean had become oxic after 0.6 Ga. Efficient circulation maintained oxygenic conditions in most parts except in well-defined O2 deficient zones.
However, Dr. Naqvi explained that, human activities are causing a decrease in oxygen content of seawater. Global oceanic oxygen inventory has already decreased by over 2% in the last 50-60 years. The ocean deoxygenation is expected to have severe impacts on marine ecology, elemental cycling and on the climate.
After this Dr. Wajih Naqvi proficiently answered the questions posed by the students.
One of the questions was asked by Naisa Ansani. She asked whether in the coming years there would be a computing device capable of visualising what we think.
He said that as a child he could not have thought of the technological advancements we have achieved, such as the internet. He said that going by this analogy it could be possible for such a device to exist in the near future. However, he said that he felt that this was not likely to happen. He concluded that the answer to the question is uncertain.
A few other questions were asked which were beautifully and brilliantly answered by Dr. Naqvi
After this Aariz Shaikh, a student of class 11th summarised the lecture and proposed vote of thanks on behalf of the Institution.
I would like to thank Dr. Naqvi for taking time out of his busy schedule to impart his invaluable knowledge to us. I would also like to thank our Director Sir Vyankatesh Prabhudesai fororganizing the guest lectures which give us the opportunity to interact with such eminent personalities from time to time and allow us to learn new and exciting things.
Aariz ShaikhXI Regular, MAHSS