22-Mar-2020: Fish fossil show how fins evolved into human hands
Researchers have revealed new insights into how the human hand evolved from fish fins based on their analysis of an ancient fossil found in Miguasha, Canada.
Palaeontologists, including those from Flinders University in Australia, said the fish specimen has yielded the missing evolutionary link in the transition from fish to four legged animals.
This happened during the Late Devonian period, millions of years ago, as fish began to foray in habitats such as shallow water and land.
The 1.57 m long fossil shows the complete arm — pectoral fin — skeleton for the first time in any elpistostegalian fish.
Using high energy X-Ray CT-scans, the scientists assessed the skeleton of the pectoral fin, revealing the presence of a humerus (arm), radius and ulna (forearm), rows of carpus (wrist) and phalanges organized in digits (fingers).
This is the first time that we have unequivocally discovered fingers locked in a fin with fin-rays in any known fish. The articulating digits in the fin are like the finger bones found in the hands of most animals.
The finding, according to the researchers, pushes back the origin of fingers in vertebrates to the fish level. They said it also reveals that the patterning for the vertebrate hand was first developed deep in evolution, just before fishes left the water.
The evolution of fishes into four-legged vertebrates was one of the most significant events in the history of life. With this adaptation, vertebrates, or back-boned animals, were then able to leave the water and conquer land.
To complete this transition, one of the most significant changes was the evolution of hands and feet. The origin of digits relates to developing the capability for the fish to support its weight in shallow water or for short trips out on land. The increased number of small bones in the fin allows more planes of flexibility to spread out its weight through the fin.
2-Mar-2020: Climate Change and Water Contamination
Climate model simulation studies done by various agencies including Intergovernmental Panel on Climate Change (IPCC) project possible linkages of climate change with frequency and intensity of weather related events. However, any direct link between climate change and flooding resulting in water contamination has not been established.
The flow in rivers is dynamic and depends on many parameters such as rainfall, its distribution and intensity in the catchment, catchment characteristics and withdrawals/utilizations of water basins. Central Water Commission (CWC), Ministry of Jal Shakti monitors important/major rivers. Considering annual average flow of last 20 years of terminal sites of major rivers, no appreciable increasing/decreasing trend in total water availability in the country including the State of Bihar has been observed.
Ministry of Jal Shakti has drafted bills namely National Water Framework Bill, River Basin Management (RBM) Bill and Model Bill to ‘Regulate and Control the Development and Management of Ground Water’ for bringing reforms in water sector.
The draft RBM Bill proposes optimum development of inter-State rivers by facilitating inter-State coordination ensuring scientific planning of land and water resources taking basin/sub-basin as unit with unified perspectives of water in all its forms (including soil moisture, ground and surface water). The draft RBM Bill has been circulated to all States/Union Territories, concerned Central Government’s Ministries/Departments for pre-legislative consultations.
The National Water Framework Bill provides an overarching national legal framework based on principles for protection, conservation, regulation and management of water as a vital and stressed natural resource, under which legislation and executive action on water can take place at all levels of governance. The draft National Water Framework Bill has been circulated to States/UTs and the concerned Central Ministries for obtaining their views/comments.
Ministry has also circulated a Model Bill to ‘Regulate and Control the Development and Management of Ground Water’ to all the States/UTs to enable them to enact suitable ground water legislation for regulation for its development which includes provision of rain water harvesting. So far, 15 States/UTs have adopted and implemented the ground water legislation on the lines of Model Bill.
2-Mar-2020: Black carbon from agricultural burning & forest fire may influence melting of Gangotri Glacier
The already receding Gangotri glacier seems to have more bad news in store. Black carbon concentration in the region increases by 400 times during summer, according to a study. The study suggests that agricultural burning and forest fire as the reason behind this seasonal increase. This can trigger glacial melt because of the light-absorbing nature of black carbon.
Scientists from Wadia Institute of Himalayan Geology, (WIHG) an autonomous institution under Department of Science & Technology in a study conducted at Chirbasa station near Gangotri Glacier, for the Year 2016, found that black carbon (BC) concentration in this region has changed from 0.01μgm−3 in winter to 4.62μgm−3 during summer.
It was revealed by investigating the occasional high values of black carbon extricated, that the seasonal cycle of increase was significantly influenced by the emissions resulting from agriculture burning (in western part of the country), forest fires (along the Himalayan slopes) in summer, and to some extent by the contribution from long-range transport of pollutants in winter, depending the prevailing meteorological condition.
The research led by Dr. P.S. Negi from WIHG was published in the scientific journal Atmospheric Environment.
The Equivalent Black Carbon (EBC) aerosols contribute significantly towards global warming due to its light-absorbing nature. Their presence in the eco-sensitive zone, such as the Himalayan glacier valleys, is a matter of serious concern and needs to be meticulously monitored. However, baseline data on BC is rarely available from most of the glaciated Himalayan region.
For the first time, the team of Scientists from WIHG carried out measurements on ambient EBC mass concentration at a high altitude site Chirbasa (3600 m), near Gangotri Glacier in the Indian Himalaya, during the year 2016. The monthly mean concentration of EBC was found to be minimum in August and maximum in the month of May. The observed seasonal mean concentrations of EBC indicated a pristine glacial source and absence of EBC sources in the locality.
16-Aug-2017: Airplanes may be affecting ozone layer by releasing black carbon
Airplanes may be ejecting significant amounts of black carbon (BC). Climate researchers from multiple institutions in India including from the Indian Institute of Science and ISRO’s Vikram Sarabhai Space Centre, made a study about BC a pollutant known to aggravate breathing disorders, upset the monsoon and quicken glacier melt. Black Carbon may also be depleting the ozone layer.
The term black carbon was coined by Tihomir Novakov in 1970s. Black Carbon is formed through the incomplete combustion of fossil fuels, biofuel, and biomass. It is known to dissipate and settle down in a few months under the influence of rain and wind and is unlikely to travel upward of 4 km. However, as per the study, the climate researchers have evidence of such particles existing up to 18 km into the stratosphere and there are about 10,000 of them in every cubic centimetre.
The stratosphere is a stable region of the atmosphere and because BC particles absorb heat, they warm the surrounding air, become lighter and rise to greater heights by a process called ‘self-lift’ and persist in the air. Given the shape and location of these particles, researchers believe that it could only derive from emissions from aviation fuel.
Negative Effects of Black Carbon:
- These Black Carbon particles can create problem as they can linger long enough to provide a fertile ground for other chemical reactions that can deplete the ozone layer.
- Because BC particles strongly absorb solar and terrestrial radiation and heats up the atmosphere, it can upset the monsoon system.
- If deposited on snow, it could accelerate the heating of snow and quicken the melting of glaciers.