Tuesday, June 29, 2021

Lichens as indicators of less air pollution in and around Ranchi city, India.


Ranchi is one of the 100 cities chosen as part of India’s smart cities program.


Dr. Nitish Priyadarshi

Assistant Professor, 

Department of Geology,

Ranchi University,



emaiil: nitish.priyadarshi@gmail.com 

Urbanization and migration of people from rural areas to the Ranchi city has badly affected the environment of the city which was earlier known as summer capital of Bihar/ Jharkhand united due to its healthy climate and less pollution. Ranchi is the capital of the Jharkhand, formed in 2000, along with Chhattisgarh, and is one of the 100 cities chosen as part of India’s smart cities program. From the time the state was formed in 2000, the number of vehicles in the city has increased 20 times, contributing to the increase in air pollution. With an increase in population – this erstwhile hill station is now dealing with haphazard construction, insufficient systems for solid waste management leading to open burning and an increase in emissions from transport. Other sources include ones such as the burning of firewood and other organic material for heating and cooking, as well as the open burning of garbage and refuse. The main types of pollutants found in the air in Ranchi would be ones that arise from the number of different combustion sources. These would include materials such as black carbon and volatile organic compounds (VOC's), both of which find origin in the incomplete combustion of both fossil fuels as well as organic material, and as such will be emitted from sources ranging from car engines, factory processes to even the burning of firewood or other raw materials. Some examples of VOC's include chemicals such as benzene, toluene, xylene, methylene chloride and formaldehyde.


Other pollutants would be ones such as nitrogen dioxide (NO2), sulfur dioxide (SO2) alongside polynuclear aromatic hydrocarbons, polychlorinated biphenyls, dioxins, furans and even heavy metals such as lead, mercury and cadmium. 


Nowadays, more than half of the human population live in urban areas and this number is increasing. This huge and often unregulated phenomenon has changed dramatically the environmental conditions of previous rural and natural areas, causing atmospheric and acoustic pollution, loss of biodiversity and climatic alterations, with harmful consequences for ecosystem functioning and human health.

Photographs posted here are from different areas near to Ranchi city. From Ranchi city lichens are mostly absent. In forest areas lichens are still found on the rocks, and trees indicating good air quality.

The earliest accounts of the high  sensitivities  of lichens to atmospheric pollution appeared around the peak of the Industrial Revolution in western Europe. Grindon (1859) in Manchester and Nylander (1866) in Paris both associated the disappearance of lichens from their respective cities with the grossly polluted town air , smoke and sulphur dioxide then being major components of the pollution.   

Fresh, clean air is wonderful to breathe in. Without the health risks of air pollution, fresh air feels great for our lungs.  Lichens love clean air too- infact their sensitivity to air pollution means they make great air quality indicators.

Basically, lichens depend on atmospheric moisture: rain, fog and dew for growth. There are slow in growth and very sensitive towards the changing environmental conditions. Since, they absorb water and essential nutrients from atmosphere instead of from soil, hence they respond in altered manner to increased concentrations of pollutants in air. Comparison of lichens growth in polluted and healthy environment, a clear cut change in growth as well as addition or reduced growth can be observed.


Like small signposts, these curious organisms can tell us a lot about the air we are breathing. Butterflies, nematodes, frogs, and toads are very good indicators of environmental pollutants, but lichens are easier to study and are quicker to respond to environmental change.

Next time you are on a walk, you can look around for the types of lichens that grow in your area. As a rule of thumb, the smaller the size and less variety of lichens in an area, the more polluted is the environment.  Main air pollutants that affect lichen growth are nitrogen, sulphur dioxide, fluorides, ozone, hydrocarbons, and metals such as copper, lead, and zinc.

Lichens look like spots or clumps of colour, like someone has splashed paint onto a branch of a tree. Their colours range from green to brown to white to russet red. Even in these colours, lichens can be understated additions to tree trunks and rocks. Because lichens have no roots or protective surface, they cannot filter what they absorb, so whatever is in the air is taken straight inside. If there are pollutants, it can accumulate in the lichen and can become toxic very quickly.

We breathe in harmless nitrogen gas all the time - in fact it makes up a large part of Earth's atmosphere. But when nitrogren is heated and combined with oxygen (as it is in a car engine), nitrogen oxides are created.

Nitrogen dioxide in the air can be a powerful polluter and becomes harmful for human health in high concentrations.  

In high concentrations, sulphur dioxide can irritate the mucus lining of the eyes, nose, throat and lungs. Exposure to sulphur dioxide may cause coughing and tightness in your chest. People with asthma are more sensitive to sulphur dioxide pollution.  

Throughout history, people have used lichens for food, clothing, dyes, perfume additives, medicines, poisons, tanning agents, bandaging, and absorbent materials. Compounds unique to lichens are used in perfumes, fiber dyes, and in medicines for their antibacterial and antiviral properties.

Lichens have been used in the treatment of diverse diseases like arthritis, alopecia, constipation, kidney diseases, leprosy, pharyngitis rabies, infection, worm and infestation. The medicinal utility of lichens is regarded to presence of secondary compounds like of usnic acid and atranorin.  It is also used in treating wounds, skin disorders, respiratory and digestive issues, and obstetric and gynecological concerns.


Bell, J.N.B. and Treshow, M. (2002). Air pollution and plant life. John Wiley & Sons, Ltd. 309-342.

Grindon, L.H. (1859). The Manchester flora. London: W. White.

Nylander,W. (1866). Les lichens du Jardin du Luxembourg. Bulletin de la Societe Botanique de France 13,364-372




Monday, March 29, 2021

Role of geology in interpreting Paleoclimate of the earth.

 Rock types as indicators of ancient climate.


Dr. Nitish Priyadarshi

The Earth’s climate has changed dramatically over the eons, as the atmosphere continuously interacts with oceans, lithosphere, and biosphere over a wide range of timescales. Efforts to place recent climate observations into a longer-term context have been stimulated by concern over whether the twentieth century global warming trend is part of natural climate variability or linked to increasing anthropogenic inputs of greenhouse gases into the atmosphere. The ability to decipher past climates has expanded in recent years with an improved understanding of present climatic processes and the development of more sophisticated analytical tools. 

Scientists know the Earth's average temperature has increased approximately 1°F since 1860. Is this warming due to something people are releasing into the atmosphere or natural causes? Many people today are quick to blame the greenhouse effect for global warming, but the temperature increases may have a natural cause, for example, from elevated volcanic activity. Gases in the earth’s atmosphere which trap heat, and cause an increase in temperature cause the greenhouse effect. Carbon dioxide (CO2), water vapour, and other gases in the atmosphere absorb the infrared rays forming a kind of blanket around the earth. Scientists fear that if humans continue to place too much carbon dioxide in the atmosphere, too much heat will be trapped, causing the global temperature to rise and resulting in devastating effects. Some scientists speculate that natural events like volcanic eruptions or an increase in the sun's output, may be influencing the climate. Perhaps the temperature rise is a natural trend that is part of a long-term cycle. Obviously, using only the weather data scientists have collected in the past 140 years will not be sufficient to answer these questions, so scientists use paleoclimactic studies to determine if today’s warming climate has occurred anytime in the past. Through past climate studies, scientists can predict what future climates and trends may occur.

Paleoclimate studies focus on both determining the climate states of the earth during the geological past and understanding how the climate system worked to produce those ancient environments. The careful observation, collection and interpretation of geological evidence from as many independent sources as possible is the most reliable way of determining details of ancient climate states. For many geological periods, paleoclimatic data are still new, and more rigorous methods for interpreting the data that we already have are needed ( Francis, 1998). The most exciting aspect of this geological research is that we can study unique environments that existed on earth in the past that are no longer present in our modern world, such as forests and dinosaurs living in warm climates in the polar regions and the extreme environments inn continental interiors on supercontinental landmasses such as Pangaea. 

Over Earth history, the climate has changed a lot. For example, during the Mesozoic Era, the Age of Dinosaurs, the climate was much warmer and carbon dioxide was abundant in the atmosphere. However, throughout the Cenozoic Era (65 Million years ago to today), the climate has been gradually cooling. How do we know about past climates? Geologists use proxy indicators to understand past climate. A proxy indicator is a biological, chemical, or physical signature preserved in the rock, sediment, or ice record that acts like a “fingerprint” of something in the past . Thus they are an indirect indicator of something like climate. 

The study of climates during the geological past, is one of the most topical areas of research in the geosciences at present. The threat of future climate change caused by higher levels of greenhouse gases, which would drastically alter many aspects of our environment, has prompted research to try to understand how our complex climate system works. Only by understanding how climate has evolved over millions of years can we identify important climate cycles with a frequency in excess of the short climate records we possess.  These climate cycles have the potential to have a profound effect on our environment. Earth's climate has shifted dramatically and frequently during the last few million years, alternating between ice ages, when vast glaciers covered northern Europe and much of North America, and interglacials — warm periods similar to the present. Geoscientists use "proxies", or indirect means to reconstruct climates that existed long before the invention of thermometers, barometers, or other meteorological instruments: tree rings, pollen grains, animal and plant fossil assemblages. Understanding our climate history in the geological past is also important for climatologists trying to construct accurate numerical computer models of our present climate system to use for predicting future climate change.

Minerals also furnish important clues about ancient climates. At Earth's surface, minerals interact closely with water and the atmosphere. Most useful are those deposited under relatively narrow climatic ranges or within specific environmental settings. These include evaporites, low temperature minerals such as ikaite and hydrohalite, minerals of residual soils (e.g., in bauxites or laterites), and some clay minerals like kaolinite.The formation of some rock types is directly influenced by aspects of climate. Some of the most useful are coals, evaporates, glacial deposits and carbonates.


Evaporite minerals form by evaporation of seawater or lakes in narrow basins, rift valleys (like the East African Rift Valley), and coastal lagoons under extremely hot and dry climates. Their distribution closely matches that of deserts. As water evaporates from the basin, salts precipitate in a sequence usually starting with carbonates, sulfates, and ending with the more soluble chloride salts. Typical evaporite minerals include gypsum, anhydrite, halite (rock salt), borax, and nitrates, such as saltpeter or niter (potassium nitrate). Major deposits of rock salt occur in the Gulf Coast, the Austrian Alps, the Dead Sea, upstate New York, Michigan, and elsewhere.

Climate Clues from Soils and Sediments

Clay minerals form by the chemical break-down of rocks near Earth's surface. The detritus is removed by water erosion and accumulates in lakes, estuaries, and the sea. Clays also occur in terrestrial soils and airborne dust. The types of clay minerals and their relative abundances are closely related to climate, although the composition of the source rocks can also influence their development. Kaolinite, for example, is created by intense chemical weathering in warm, humid climates where silica is leached out, leaving soils enriched in alumina. Chlorite and illite, on the other hand, tend to form in soils dominated by mechanical weathering, both in colder, often formerly glaciated regions, but also in hot, dry climates.



Bauxite is a residual soil that forms by intense chemical weathering of rocks in wet, tropical climates where the average rainfall is 60 inches/year. The extreme leaching destroys most silicates and even resistant minerals such as quartz, leaving insoluble aluminum minerals, such as gibbsite, and boehmite, with lesser quantities of diaspore, kaolinite, and iron oxides. Laterite and bauxite peaks were coeval with times of global high warmth and precipitation, elevated atmospheric carbon dioxide, oceanic anoxia, exceptional fossil preservation, and mass extinction.


Just as evaporates indicate hot and dry climates, occurrences of coal in the geologic record suggest hot and wet climates. The presence of coal, initially formed from the accumulation of plant materials as peat, is generally taken to indicate warm and wet humid climates ideal for lush plant growth, and where the rainfall is higher than the rate of evaporation, such as in equatorial regions. However, rainfall is a more important factor than temperature, as are high water tables and waterlogged swamps which are required to preserve the peat.

In the past, the most abundant coal deposits were formed during the Carboniferous when large subsiding continental areas were situated in low latitudes and experienced hot and humid climate.


Coral reefs provide paleoclimatologists with important proxy data. Coral reefs have been a part of the Earth's oceans for millions of years and are very sensitive to changes in climate. Scientists can use indicators from corals to study weather conditions from the past hundreds or even thousands of years to determine trends in climate. Corals form skeletons by extracting calcium carbonate from the ocean waters. When the water temperature changes, calcium carbonate densities in the skeletons also change. Coral formed in the summer has a different density than coral formed in the winter. This creates seasonal growth rings on the coral (like rings on a tree). Scientists can study these rings to determine the temperature of the water, and the season in which the coral grew. By using these growth bands, scientists can date the coral samples to an exact year and season.

Glacial deposits.


Evidence for glaciation and the presence of thick ice sheets can be obtained from a variety of sources. The most convincing are striated pavements, that is surfaces of bedrock with the grooves scratched by debris frozen into the base of moving ice glaciers. The orientation of ice movement and therefore in some cases the position of glacial centres can also be determined. For example, studies of Carboniferous and Permian glacial deposits in the Southern Hemisphere enabled Crowell and Frakes ( 1975) to reconstruct the location of ice centres over Gondwana continents and to determine the direction of movement of ice lobes from these centres.

Glacial tillites can provide information about ice passage but, in the absence of other glacial features, tillites can sometimes be hard to distinguish from other diamictites, such as debris flow deposits, which may have formed under totally different conditions. Ice –rafted dropstones and varves indicate that ice formed, at least seasonally, and produced dumps of ice carried debris or seasonal lake sediments. In addition, glendonite nodules have also been used as evidence for cold climates, particularly for the Permian from which sequences they were originally described.


Crowell, J.C. , Frakes, L.A. 1975. The Late Palaeozoic glaciation. In Campbell, K.S. (ed.) Gondwana Geology. Australian National University Press, Canberra, 313-331.

Francis, J.E. 1998. Interpreting Palaeoclimates. In Peter, D. and Matthew R.B. (ed.) Unlocking the Stratigraphical Record. Advances in Modern Stratigraphy. John Wiley & Sons, 471-490.





Wednesday, March 10, 2021

My experience with Forest Fires.


Raging ground fire in forests of Ranchi and its surrounding is posing a threat to environment.


Dr. Nitish Priyadarshi.

Environmentalist and Assistant Professor Department of Geology,

Ranchi University, India.

“Forest”– whenever we hear this word, all our mind presumes is – a vast area of land covered with green patches, which may consist of wildlife flourished with different verities of flora and fauna, and of course tribal people residing and relying in & on the forest respectively. 

It was 6th March 2021.  I decided to drive for Sita falls and Jonha falls near Ranchi city, capital of Jharkhand state, India. Both the falls are situated deep into the dense forests of Jharkhand.  I took my kids with me.  Weather was quite and dry with 26 degree centigrade. As I was about to reach Sita Falls my son saw smoke coming out of the forest. Valley was covered with dense smoke. As we got closer to our destination and further deep into the forest I saw aggressive flames of fire coming out of forest beds in different geometrical forms. Mild, hot and dry winds of spring were triggering the fire. I stopped my car to observe this scenario up close and take few pictures. 

As the trees had shed their leaves to welcome the new ones, the forest soil was covered with dry leaves which helped accelerate flames throughout. The forest birds were in distress as high flames caused immense heat and smoke which prevented them from approaching their nests at twilight. I thought I could feel people in the forest, but when I looked around, not a soul was there.  As I continued my journey, the trees started to shiver with the impact of blowing wind and fire and the birds cried out in fear as they fled from their nests. Whistling sound of burning fire was scary.

The smell of burning wood flew through the air. Twigs and dead leaves made a deafening crunch underneath my feet. The further I and my kids went in to the forest the more frightened we got due to spreading flames. It was so hot in the forest area that I could almost feel a burning sensation on my skin. You can well imagine how badly it is affecting the wide variety of birds living in the jungle. Being an environmentalist I can access how much carbon dioxide may have emitted due to these fires.

The composition of wildfire smoke is primarily made of carbon dioxide, water vapor, carbon monoxide, particulate matter, hydrocarbons and other organic chemicals, nitrogen oxides, and many other trace elements. However, smoke composition can vary, depending on the fuel type, fire temperature, and wind conditions. Of these pollutants, particulate matter (PM) is the most concerning, given their very small size and ability to be inhaled deeply into the lungs.

Exposure to PM generated from wildfires has been associated with a wide range of human health effects, such as wheezing, coughing, sore eyes and throats, and shortness of breath, to more adverse health outcomes, ranging from increases in asthma-related hospitalizations, chronic and acute respiratory and cardiovascular health outcomes, and premature death.

But why did these fires happen in Jharkhand?

Ranchi has a hilly topography and its dense Tropical Dry Deciduous forest a combination that produces a relatively moderate climate compared to the rest of the state.

Forest fires lit by villagers to collect mahua (Madhuca longifolia ) – a wild flower used for making country liquor – is posing to be a threat to the flora and fauna in Jharkhand jungles. Mahua, which grows in abundance in the forest areas of Jharkhand, falls off the trees during spring. However, these flowers are often covered by a layer of dry leaves, which make it difficult for villagers to find and collect Mahua. Villagers set forest areas afire to clear the leaves and easily spot mahua flowers, which are unaffected by fire. Villagers also make charcoal. On a basic level, charcoal is produced by burning wood  in a low oxygen environment.