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17

## What is the difference between the pyramid of numbers, pyramid of biomass and pyramid of energy?

Mandira P.
Featured 1 week ago

The names explain the purpose: pyramids are graphical representation of different aspects of ecosystem. Pyramid of energy is always upright which may not be so for pyramid of numbers or pyramid of biomass.

#### Explanation:

Energy pyramid depicts flow of energy in the ecosystem: source of all energy in ecosystem is the SUN. Producers are only organisms in ecosystem who can trap the solar enrgy. So base of energy pyramid is always wide.

Now let us see a pyramid of numbers which depicts the number of individual organisms per trophic level: in an orchard producers are some large trees, but the trees will support a large number of consumers, such as insects and birds. A pyramid of numbers in such ecosystem will be inverted as seen in the following illustration:

A biomass pyramid shows the total dry mass of all living organisms at each trophic level. An inverted pyramid of biomass could be seen when we study aquatic ecosystems, like a lake. The phytoplanktons at a given time is less in biomass but their lifecycle is very short; they actually reproduce faster than the consumers dependent on them.

1

## Hazardous waste generators are liable for mismanagement of waste, even after it leaves the site, for how long?

G_Ozdilek
Featured 1 week ago

Depends on waste characteristics and other factors.

1

## How is deforestation contributes to climate change?

G_Ozdilek
Featured 3 days ago

While human population rises, pressure on natural resources (such as forests) increases too.

#### Explanation:

Deforestation is related to human population growth that leads to ever increasing food production and animal husbandry as well as mining activities, road construction, urban sprawl etc.

Forests are important areas for carbon dioxide removal since photosynthetic plants need carbon dioxide to form sugar (glucose) and oxygen. Plants are a natural part of the carbon cycle and store CO2. If we cut trees down, they no longer remove CO2 from the atmosphere and store it.

Human activities are limitless. We construct industrial plants, open pristine areas to mining, timber production, firewood production, road construction, urbanization, etc. The easiest way to do such activities is to remove forest cover. In some cases, nobody owns the forest: It belongs to all people though but there is no private person or group claiming ownership of forests. Even when someone does own the forest, companies are willing to spend lots of money to buy that forest and then clear it for development.

Over the past 100 years or 50 years, there is a huge drop in forest areas because humans do not care about importance of forests or do not recycle wastes. Deforestation has been occurring at a fast rate right now triggering global climate change, erosion, loss of lives and properties, etc.

1

## Is underground water hot in the winter and cold in the summer?

David Drayer
Featured 3 days ago

Seasons do not greatly affect underground water sources.

#### Explanation:

Underground springs that bring melted snow water underground to a surface source are cold even in the middle of summer. The ground insulates the water that entered the aquifer at cold high altitudes keeping it cold regardless of air temperatures.

Underground springs, known as hot springs, get their heat by contact with the heated magma underneath the earth's surface. This hot springs will be close to boiling hot even in the middle of winter when there is snow on the ground.

The temperature of underground water sources depends on the source of the water not the air temperatures.

2

## Water covers 70% of Earth’s surface, yet the authors state that "The single biggest water problem worldwide is scarcity." Defend the authors’ assertion that water scarcity is a problem now, and explain why it will intensify in the future?

David Drayer
Featured 2 days ago

Most of this water is salt water and usable freshwater is much more rare. Increased demands and climate change are predicted to increase scarcity.

#### Explanation:

The Oceans cover vast areas of the globe but the salt water in these oceans is not useable for either drinking or irrigation. There are many fresh water lakes, notably the Great Lakes of America and Canada, the water in these lakes must be filtered and cleaned before the water can be used for human consumption.

Many rivers are used not only for drinking and irrigation but also for the disposal of waste products. The human waste is dumped into the rivers making the water downstream unusable until it has been treated.

There is a limit amount of usable fresh water. Much of the water has
been polluted and will become more polluted. At the same time the human population of the world is increasing, increasing the need for fresh water. The scarcity of fresh water will only increase in intensity as the demand for fresh water increases.

The image below shows water stress by country:

Prediction of future water scarcity:

Changes in temperature , precipitation patterns (both due to climate change), and increase in demand are all drivers behind projected increased scarcity.