Category Social Sciences

WHAT IS NITROGEN CYCLE? WHAT ARE THE STAGES OF NITROGEN CYCLE?

Our atmosphere is made up of 78% nitrogen. This element is essential for all living beings but we cannot directly take the nitrogen from the environment. We must absorb it through our food. The nitrogen cycle follows the circulation of nitrogen from the atmosphere to the soil, to animals and back. Nitrogen in the atmosphere falls to the earth through snow and rain. Once in the soil, the nitrogen combines with the hydrogen on the roots of the plants to form ammonia. This process is called Nitrogen fixation. Additional bacteria further combine this ammonia with oxygen in a process called Nitrification. At this point, the nitrogen is in a form called nitrite, which is further converted into nitrate by the bacteria. Plants can absorb nitrogen in this state through a process called assimilation and the rest is utilised by the bacteria. The remainder is released back into the atmosphere through the process of denitrification.

Nitrogen Cycle Explained – Stages of Nitrogen Cycle

Process of the Nitrogen Cycle consists of the following steps – Nitrogen fixation, Nitrification, Assimilation, Ammonification and Denitrification. These processes take place in several stages and are explained below:

Nitrogen Fixation Process

It is the initial step of the nitrogen cycle. Here, Atmospheric nitrogen (N2) which is primarily available in an inert form, is converted into the usable form -ammonia (NH3).

During the process of Nitrogen fixation, the inert form of nitrogen gas is deposited into soils from the atmosphere and surface waters, mainly through precipitation.

The entire process of Nitrogen fixation is completed by symbiotic bacteria, which are known as Diazotrophs. Azotobacter and Rhizobium also have a major role in this process. These bacteria consist of a nitrogenase enzyme, which has the capability to combine gaseous nitrogen with hydrogen to form ammonia.

Nitrogen fixation can occur either by atmospheric fixation- which involves lightening, or industrial fixation by manufacturing ammonia under high temperature and pressure conditions. This can also be fixed through man-made processes, primarily industrial processes that create ammonia and nitrogen-rich fertilisers.

Assimilation

Primary producers – plants take in the nitrogen compounds from the soil with the help of their roots, which are available in the form of ammonia, nitrite ions, nitrate ions or ammonium ions and are used in the formation of the plant and animal proteins. This way, it enters the food web when the primary consumers eat the plants.

Ammonification

When plants or animals die, the nitrogen present in the organic matter is released back into the soil. The decomposers, namely bacteria or fungi present in the soil, convert the organic matter back into ammonium. This process of decomposition produces ammonia, which is further used for other biological processes.

Denitrification

Denitrification is the process in which the nitrogen compounds make their way back into the atmosphere by converting nitrate (NO3-)  into gaseous nitrogen (N). This process of the nitrogen cycle is the final stage and occurs in the absence of oxygen. Denitrification is carried out by the denitrifying bacterial species- Clostridium and Pseudomonas, which will process nitrate to gain oxygen and gives out free nitrogen gas as a byproduct.

Conclusion

Nitrogen is abundant in the atmosphere, but it is unusable to plants or animals unless it is converted into nitrogen compounds.

Nitrogen-fixing bacteria play a crucial role in fixing atmospheric nitrogen into nitrogen compounds that can be used by plants.

The plants absorb the usable nitrogen compounds from the soil through their roots. Then, these nitrogen compounds are used for the production of proteins and other compounds in the plant cell.

Animals assimilate nitrogen by consuming these plants or other animals that contain nitrogen. Humans consume proteins from these plants and animals. The nitrogen then assimilates into our body system.

During the final stages of the nitrogen cycle, bacteria and fungi help decompose organic matter, where the nitrogenous compounds get dissolved into the soil which is again used by the plants.

Some bacteria then convert these nitrogenous compounds in the soil and turn it into nitrogen gas. Eventually, it goes back to the atmosphere.

These sets of processes repeat continuously and thus maintain the percentage of nitrogen in the atmosphere.

Credit : BYJU’S 

Picture Credit : Google 

WHAT ARE MANGROVES?

Mangroves are bushes or trees that grow in thick clusters along sea coasts and riverbanks.

Their roots stick out of the mud in thick tangles and prevent the waves from washing away the sand (or dirt) from the coastline Sundarbans in Bangladesh and India is the world’s largest single tract of mangroves.

Where Are Mangroves Found?

Mangroves grow in sheltered tropical and subtropical coastal areas across the globe. In general, this is an area between latitudes of 25 degrees north and 25 degrees south, however, geographical limits are highly variable depending upon the area of the world and local climates. In Eastern Australia, the mangrove Avicennia marina can grow as far south as 38 degrees and Avicennia germinans can grow as far north as 32 degrees in the Atlantic. A major restriction for where mangroves can live is temperature. The cooler temperatures of northern temperate regions prove too much for the mangroves. A fluctuation of ten degrees in a short period of time is enough stress to damage the plant and freezing temperatures for even a few hours can kill some mangrove species. However, rising temperatures and sea level due to climate change are allowing mangroves to expand their ranges farther away from the equator and encroach on temperate wetlands, like salt marshes. Also, on some isolated tropical islands, such as Hawaii and Tahiti, mangroves are not native and are sometimes considered invasive species.

Growth and Reproduction

Life by the ocean has its perks—for mangroves, proximity to the waves and tides helps with reproduction.

For most plants, the seeds remain dormant until after they are dispersed to a favorable environment. Not mangroves. Mangrove offspring begin to grow while still attached to their parent. This type of plant reproduction is called vivipary. After mangrove flowers are pollinated the plants produce seeds that immediately begin to germinate into seedlings. The little seedlings, called propagules, then fall off the tree, and can be swept away by the ocean current. Depending upon the species, propagules will float for a number of days before becoming waterlogged and sinking to the muddy bottom, where they lodge in the soil. Propagules of Rhizophora are able to grow over a year after they are released from their parent tree, while the white mangrove, Laguncularia racemosa, floats for up to 24 days, though it starts losing its ability to take root after eight. The flotation time allows for the propagules to vacate the area where their parent grows and avoid competition with an already established mangrove.

Mangroves as Ecosystems

Mangroves are among the most productive and biologically complex ecosystems on Earth. They cover between roughly 53,000 and 77,000 square miles (138,000 and 200,000 square km) globally, acting as a bridge connecting the land and sea. Though most will be less than a couple miles thick along the coastline, in some areas of the world they are massive aquatic forests. The Sundarbans Forest, a UNESCO World Heritage site at the mouth of the Ganges, Brahmaputra, and Megha Rivers in the Bay of Bengal fronting India and Bangladesh, is a network of muddy islands and waterways that extends roughly 3,860 square miles (10,000 square km), two times the size of the state of Delaware.

Credit : Ocean find your blues

Picture Credit : Google

WHAT IS A MONSOON SEASON?

A monsoon is a seasonal wind pattern that lasts for several months and results in heavy rainfall during the summer and dry spells in the winter. It is responsible for the wet and dry seasons throughout much of the tropics. Typically Indian monsoon lasts from June-September, with large areas of western and central India receiving more than 90% of their total annual precipitation during the period. The word comes from the Arabic ‘mausin’ which means season and was first used in the English language during the British occupation of India.

What causes a monsoon?

A monsoon (from the Arabic mawsim, which means “season”) arises due to a difference in temperatures between a land mass and the adjacent ocean, according to the National Weather Service. The sun warms the land and ocean differently, according to Southwest Climate Change, causing the winds to play “tug of war” eventually switching directions bringing the cooler, moister air from over the ocean. The winds reverse again at the end of the monsoon season.

Wet versus dry

A wet monsoon typically occurs during the summer months (about April through September) bringing heavy rains, according to National Geographic. On average, approximately 75 percent of India’s annual rainfall and about 50 percent of the North American monsoon region (according to a 2004 NOAA study) comes during the summer monsoon season. The wet monsoon begins when winds bringing cooler, more humid air from above the oceans to the land, as described above.

A dry monsoon typically occurs between October and April. Instead of coming from the oceans, the winds tend to come from drier, warmer climates such as from Mongolia and northwestern China down into India, according to National Geographic. Dry monsoons tend to be less powerful than their summer counterparts. Edward Guinan, an astronomy and meteorology professor at Villanova University, states that the winter monsoon occurs when “the land cools off faster than the water and a high pressure develops over the land, blocking any ocean air from penetrating.” This leads to a dry period.

The winds and rains

The monsoon season varies in strength each year bringing periods of lighter rains and heavier rains as well as slower wind speeds and higher wind speeds. The Indian Institute of Tropical Meteorology has compiled data showing yearly rainfalls across India for the last 145 years.

According to the data, the intensity of a monsoon varies over an average of period of 30 – 40 years. In each period, the amount of rain received is higher than average resulting in many floods or lower than average resulting in droughts. The long-term data suggest that the monsoon trends may turn from being in a low rain period that began in approximately 1970 to a higher rain period. Current records for 2016 indicate that total rainfall between June 1 and September 30 is 97.3 percent of the seasonal normal.

The most rain during a monsoon season, according to Guinan, was in Cherrapunji, in the state of Meghalaya in India between 1860 and 1861 when the region received 26,470 millimeters (1,047 inches) of rain. The area with the highest average annual total (which was observed over a ten year period) is Mawsynram, also in Meghalaya, with an average of 11,872 millimeters (467.4 inches) of rain.

The average wind speeds in Meghalaya during peak summer monsoon season average 4 kilometers per second and typically vary between 1 and 7 kilometers per hour, according to Meteoblue. During the winter months, wind speeds typically vary between 2 and 8 kilometers per hour with an average of 4 – 5 kilometers per hour.

Credit : Live science 

Picture Credit : Google 

WHAT IS LA NINA WEATHER?

La Nina is a climatic pattern that refers to the cooling of the ocean surfaces along the tropical west coast of South America. During this weather pattern, warm ocean water and clouds move westwards increasing the chances of places like Indonesia and Australia getting much more rain than usual. These fluctuations tend to leave the regions of southwestern U.S. extremely dry.

The most severe La Nina occurrence in recent history was the 1988-89 event, which led to a seven-year drought in California. La Niña is a complex weather pattern that occurs every few years, as a result of variations in ocean temperatures in the equatorial band of the Pacific Ocean, The phenomenon occurs as strong winds blow warm water at the ocean’s surface away from South America, across the Pacific Ocean towards Indonesia. As this warm water moves west, cold water from the deep sea rises to the surface near South America; it is considered to be the cold phase of the broader El Niño–Southern Oscillation (ENSO) weather phenomenon, as well as the opposite of El Niño weather pattern. The movement of so much heat across a quarter of the planet, and particularly in the form of temperature at the ocean surface, can have a significant effect on weather across the entire planet.

Tropical instability waves visible on sea surface temperature maps, showing a tongue of colder water, are often present during neutral or La Niña conditions.

La Niña events have occurred for hundreds of years, and occurred on a regular basis during the early parts of both the 17th and 19th centuries. Since the start of the 20th century, La Niña events have occurred during the following years:

1903–04
1906–07
1909–11
1916–18
1924–25
1928–30
1938–39
1942–43
1949–51
1954–57
1964–65
1970–72
1973–76
1983–85
1988–89
1995–96
1998–2001
2005–06
2007–08
2008–09
2010–12
2016
2017–18
2020–22

Credit :  Wikipedia 

Picture redit : Google 

WHAT IS THE DEFINITION OF GLOBAL WARMING?

The long-term heating up of the planet due to human activity since the 19th century pre-industrial era is called global warming. One of the main causes driving global warming is the burning of fossil fuels which increases the level of heat-trapping greenhouse gases in the atmosphere. Research has pointed out that human activities have increased the earth’s average temperature by about 1 degree Celsius. From the atmosphere to ocean and land, the temperature is rising. The figure is projected to increase with every passing decade. Rising temperatures can impact sea level, thaw glaciers, affect rainfall patterns and lead to extreme events such as hurricanes, flash floods and tomados.

What causes global warming?

Global warming occurs when carbon dioxide (CO2) and other air pollutants collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the earth’s surface. Normally this radiation would escape into space, but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter. These heat-trapping pollutants—specifically carbon dioxide, methane, nitrous oxide, water vapor, and synthetic fluorinated gases—are known as greenhouse gases, and their impact is called the greenhouse effect.

Though natural cycles and fluctuations have caused the earth’s climate to change several times over the last 800,000 years, our current era of global warming is directly attributable to human activity—specifically to our burning of fossil fuels such as coal, oil, gasoline, and natural gas, which results in the greenhouse effect. In the United States, the largest source of greenhouse gases is transportation (29 percent), followed closely by electricity production (28 percent) and industrial activity (22 percent).

Curbing dangerous climate change requires very deep cuts in emissions, as well as the use of alternatives to fossil fuels worldwide. The good news is that countries around the globe have formally committed—as part of the 2015 Paris Climate Agreement—to lower their emissions by setting new standards and crafting new policies to meet or even exceed those standards. The not-so-good news is that we’re not working fast enough. To avoid the worst impacts of climate change, scientists tell us that we need to reduce global carbon emissions by as much as 40 percent by 2030. For that to happen, the global community must take immediate, concrete steps: to decarbonize electricity generation by equitably transitioning from fossil fuel–based production to renewable energy sources like wind and solar; to electrify our cars and trucks; and to maximize energy efficiency in our buildings, appliances, and industries.

How is global warming linked to extreme weather?

Scientists agree that the earth’s rising temperatures are fueling longer and hotter heat waves, more frequent droughts, heavier rainfall, and more powerful hurricanes.

In 2015, for example, scientists concluded that a lengthy drought in California—the state’s worst water shortage in 1,200 years—had been intensified by 15 to 20 percent by global warming. They also said the odds of similar droughts happening in the future had roughly doubled over the past century. And in 2016, the National Academies of Science, Engineering, and Medicine announced that we can now confidently attribute some extreme weather events, like heat waves, droughts, and heavy precipitation, directly to climate change.

The earth’s ocean temperatures are getting warmer, too—which means that tropical storms can pick up more energy. In other words, global warming has the ability to turn a category 3 storm into a more dangerous category 4 storm. In fact, scientists have found that the frequency of North Atlantic hurricanes has increased since the early 1980s, as has the number of storms that reach categories 4 and 5. The 2020 Atlantic hurricane season included a record-breaking 30 tropical storms, 6 major hurricanes, and 13 hurricanes altogether. With increased intensity come increased damage and death. The United States saw an unprecedented 22 weather and climate disasters that caused at least a billion dollars’ worth of damage in 2020, but 2017 was the costliest on record and among the deadliest as well: Taken together, that year’s tropical storms (including Hurricanes Harvey, Irma, and Maria) caused nearly $300 billion in damage and led to more than 3,300 fatalities.

The impacts of global warming are being felt everywhere. Extreme heat waves have caused tens of thousands of deaths around the world in recent years. And in an alarming sign of events to come, Antarctica has lost nearly four trillion metric tons of ice since the 1990s. The rate of loss could speed up if we keep burning fossil fuels at our current pace, some experts say, causing sea levels to rise several meters in the next 50 to 150 years and wreaking havoc on coastal communities worldwide.

Credit : NRDC

Picture Credit : Google

WHAT IS FOOD CHAIN?

All living things need food to live and grow, and creatures eat more than one variety of plant or animal. Food chain is the sequence in which matter and energy in the form of food gets transferred from one organism to another. Unless another there is enough food available to all living organisms, their survival and the stability of the environment cannot be ensured. The prey species binge on plant life in their habitat while the predators control the prey population and outbreak of diseases. Any change in the chain can cause a ripple effect. The prey-predator relationship in many ecosystems has become complex in recent times due to threats such as global warming. climate change and loss of habitat.

There are four main elements of the food chain:

1. The Sun: The sun is the planet’s primary energy source, powering everything else.

2. The producers: All autotrophs, such as phytoplankton, cyanobacteria, algae, and green plants, are producers in a food chain. A food chain starts here. The food chain begins with the farmers and ranchers. To create food, the producers make use of solar energy. Autotrophs, who produce their own food, are another term for producers. Any plant or creature that has its own nutrition through photosynthesis is a producer. Green plants, phytoplankton, and algae, for instance, are food chain producers.

3. The consumers: All creatures that depend on plants or other organisms for nutrition are considered consumers. This is the most critical component of the food chain since it includes nearly all species of living creatures. Herbivores consume plants, carnivores eat other animals, parasites survive on other creatures by damaging them, and scavengers devour dead animals’ corpses, all of which are included in the animal kingdom.

4. The decomposers: Decomposers are creatures that get energy from dead or discarded organic material. This is the final level of the food chain. Decomposers are essential components of the food chain because they transform organic waste into inorganic materials such as nutrient-rich soil or land.

Decomposers aid in nutrient recycling by supplying nutrients to soil or seas that autotrophs or producers may use. As a result, a completely new food chain is formed.

Food Chain Types

Food chains are classified into two types: detritus food chains and grazing food chains. Let’s study them in detail:

1. Detritus food chain:
The detritus food chain includes many creatures and plants such as bacteria, protozoa fungus, algae, insects, mites, and worms. The detritus food chain begins with decomposing organic matter. Food energy is transferred to decomposers and detritivores, which are then consumed by smaller creatures such as predators. Carnivores, such as maggots, become prey for larger carnivores such as frogs, snakes, and so on. Primary consumers, such as fungus, bacteria, and protozoans, are detritivores that feed on detritus.

2. Grazing food chain:
The grazing food chain is a sort of food chain that begins with green plants and progresses via herbivores and predators. Photosynthesis provides energy to the lowest trophic level in a grazing food chain.
The initial energy transmission in this sort of food chain occurs from plants to herbivores. This food chain is based on the transfer of energy from autotrophs to herbivores. Because autotrophs constitute the foundation of all ecosystems on Earth, most ecosystems on the planet follow this type of food chain.

Credit : Akash BYJUS

Picture Credit : Google