APES Notes 1.6 - Phosphorus Cycle

Summary

In this educational video, Mr. Smeeds explores the phosphorus cycle, highlighting its slow pace compared to the carbon and nitrogen cycles. He explains the movement of phosphorus from rocks and sediments through weathering and water transport. Phosphorus, essential for life due to its role in ATP and DNA, is often a limiting nutrient in ecosystems. The video also addresses human impacts, such as mining for phosphates and the subsequent risk of eutrophication, which can lead to algal blooms and dead zones in water bodies.

Takeaways

• 🔄 The phosphorus cycle involves the movement of phosphorus between sources and sinks, similar to the carbon and nitrogen cycles.
• 💠 Major reservoirs of phosphorus are rocks and phosphorus-containing sediments, which release phosphorus slowly through weathering.
• 🌬️ The phosphorus cycle is much slower than the carbon and nitrogen cycles due to the lack of a gaseous form of phosphorus and the slow process of weathering.
• 🌱 Phosphorus is a limiting nutrient in ecosystems because its release from rocks and sediments is a slow process, affecting plant growth and availability for organisms.
• 🌿 Plants absorb phosphorus from the soil, and animals obtain it by consuming plants or other animals, creating a mini nutrient cycle within ecosystems.
• 🔗 Both natural processes like weathering and human activities such as mining contribute to the availability of phosphorus in the environment.
• 🚜 Human-made sources of phosphorus, like synthetic fertilizers and detergents, can lead to eutrophication when they enter water bodies through runoff.
• 🌊 Eutrophication, caused by excess nitrogen and phosphorus, results in algal blooms that can block sunlight and deplete oxygen in water bodies, harming aquatic life.
• 🐟 The death of aquatic plants and algae due to lack of sunlight and oxygen leads to a positive feedback loop where decomposition uses up more oxygen, creating dead zones.
• 🏞️ Geological processes like sedimentation and uplift play a role in the phosphorus cycle by forming new sedimentary rocks and exposing them to weathering.

Q & A

What is the phosphorus cycle?

The phosphorus cycle refers to the movement of phosphorus-containing elements between sources and sinks, similar to the carbon and nitrogen cycles.

What are the two major reservoirs of phosphorus?

The two major reservoirs of phosphorus are rocks and phosphorus-containing sediments.

Why is the phosphorus cycle considered to be extremely slow?

The phosphorus cycle is slow because phosphorus is released very slowly from rocks and sediments through a process called weathering, and there is no gas form of phosphorus, which means it must move in solid form.

How does phosphorus get released from rocks?

Phosphorus is released from rocks through the process of weathering, where wind and rain break down the rock and release phosphorus in the form of phosphate.

What is the role of phosphorus in ecosystems?

Phosphorus is often a limiting nutrient in ecosystems because of its slow cycle. It is essential for all organisms as it is a key element in ATP, DNA, and provides strength for bones and teeth in many animals.

How do humans contribute to the phosphorus cycle?

Humans contribute to the phosphorus cycle by mining phosphate-containing rocks and adding phosphates to synthetic fertilizers, detergents, and cleaners.

What is eutrophication and how does it relate to the phosphorus cycle?

Eutrophication is a problem that occurs when a body of water receives too much nitrogen and phosphorus, leading to excessive growth of algae, which can block sunlight and deplete oxygen in the water, creating dead zones.

How does phosphorus move from terrestrial ecosystems to aquatic ecosystems?

Phosphorus moves from terrestrial ecosystems to aquatic ecosystems through runoff, which carries phosphates from the soil into bodies of water.

What is sedimentation in the context of the phosphorus cycle?

Sedimentation in the phosphorus cycle is the process where phosphate precipitates out of water and forms solid phosphate sediments at the bottom of a body of water.

How does geological uplift affect the phosphorus cycle?

Geological uplift, where tectonic plates collide and force new rock layers to form mountains, exposes new rock to weathering, restarting the weathering process and the release of phosphorus.

What is the significance of the phosphorus cycle for plant growth?

The phosphorus cycle is significant for plant growth because phosphorus is a limiting nutrient that plants absorb from the soil, which is essential for their development and energy production.

Outlines

00:00

🔄 Phosphorus Cycle Overview

This paragraph introduces the phosphorus cycle, comparing it to the carbon and nitrogen cycles. It emphasizes the slow movement of phosphorus between sources and sinks, such as rocks and sediments, due to the lack of a gaseous form of phosphorus. The process of weathering, where rocks release phosphates, is highlighted as a key but slow step. The paragraph also notes phosphorus's importance as a limiting nutrient in ecosystems due to its slow cycle, affecting organisms' access to this essential element for ATP production and structural integrity in bones and teeth.

05:02

🌱 Natural and Synthetic Phosphorus Sources

The second paragraph delves into the sources of phosphorus, both natural and synthetic. It explains that the primary natural source is the weathering of phosphorus-containing rocks by wind and rain, which releases phosphates into aquatic and terrestrial ecosystems. Human activities, such as mining phosphate rocks and adding them to fertilizers and detergents, contribute to synthetic sources. The paragraph also addresses the environmental issue of eutrophication, caused by excess nitrogen and phosphorus inputs, leading to algal blooms and oxygen depletion in water bodies, which can result in dead zones where life cannot be supported.

Keywords

💡Phosphorous Cycle

The phosphorous cycle refers to the movement of phosphorus through various ecosystems, including its transfer between sources and sinks. In the video, it is compared to the carbon and nitrogen cycles, highlighting how phosphorus moves between rocks, sediments, and living organisms. The cycle is described as extremely slow, which makes phosphorus a limiting nutrient in ecosystems, crucial for understanding its impact on plant growth and overall ecosystem health.

💡Reservoirs

Reservoirs in the context of the phosphorous cycle are the stores or sources from which phosphorus is released into the environment. The video identifies rocks and phosphorus-containing sediments as the two major reservoirs. These reservoirs release phosphorus slowly through a process called weathering, which is central to understanding the phosphorous cycle's pace and its significance in ecosystem nutrient availability.

💡Weathering

Weathering is the process by which rocks and sediments break down due to natural forces like wind and rain, releasing phosphorus in the form of phosphate. The video explains that this process is slow, contributing to the overall sluggish nature of the phosphorous cycle. Weathering is a key mechanism in the release of phosphorus from rocks and sediments, making it accessible to ecosystems.

💡Phosphate

Phosphate is the form in which phosphorus is released from rocks and sediments through weathering. It is then transported to aquatic or terrestrial ecosystems, where it can be absorbed by plants. The video emphasizes that phosphate is a critical component for life, being a key element in ATP and DNA, and it illustrates the journey of phosphate from its source to its use by living organisms.

💡Limiting Nutrient

A limiting nutrient is an element that is in short supply and thus restricts the growth and productivity of an ecosystem. Phosphorus is highlighted as a limiting nutrient in the video due to its slow release from reservoirs. This concept is vital for understanding how the availability of phosphorus can control the health and productivity of ecosystems, particularly in terms of plant growth.

💡ATP

ATP, or adenosine triphosphate, is a molecule that stores and transfers energy within cells. The video mentions that phosphorus is a key element in ATP, which is essential for every living thing as it serves as an energy source. This illustrates the fundamental role of phosphorus in biological processes and why its availability is critical for life.

💡Natural and Synthetic Sources

The video distinguishes between natural and synthetic sources of phosphorus. Natural sources involve the weathering of phosphorus-containing rocks, while synthetic sources include human activities such as mining and adding phosphates to fertilizers and detergents. Understanding these sources is crucial for grasping how human activities can influence the phosphorous cycle and potentially lead to issues like eutrophication.

💡Eutrophication

Eutrophication is a process where an excess of nutrients, particularly nitrogen and phosphorus, leads to excessive growth of algae in bodies of water, often resulting in negative environmental impacts. The video explains how this can occur due to runoff from agricultural fields or wastewater containing phosphorus, leading to algal blooms and the creation of dead zones where oxygen is depleted, harming aquatic life.

💡Decomposition

Decomposition is the process by which organic matter is broken down into simpler compounds by decomposers, such as bacteria. In the context of the phosphorous cycle, decomposition of dead organisms returns phosphorus to the soil, as mentioned in the video. This is an essential part of the cycle, as it recycles phosphorus back into the ecosystem, making it available for plants and other organisms.

💡Sedimentation

Sedimentation is the process by which phosphates, which do not dissolve well in water, precipitate out and form solid sediments at the bottom of bodies of water. The video uses the analogy of sugar crystallizing at the bottom of a container of Kool-Aid to explain this concept. Sedimentation is a key part of the phosphorous cycle, as it leads to the formation of sedimentary rocks that can eventually be uplifted and weathered, reintroducing phosphorus into the cycle.

💡Geological Uplift

Geological uplift is the process where tectonic plate movements force rock layers to rise and form new landforms, such as mountains. As explained in the video, this process exposes new rock to weathering, which can then release phosphorus back into the environment, continuing the phosphorous cycle. Geological uplift is crucial for the long-term movement of phosphorus and its availability in ecosystems.

Highlights

The phosphorous cycle is discussed, highlighting its similarities and differences with the carbon and nitrogen cycles.

Phosphorus moves between sources and sinks, with rocks and sediments being the major reservoirs.

The phosphorous cycle is extremely slow compared to the carbon and nitrogen cycles due to the lack of a gaseous form of phosphorus.

Phosphorus is released from rocks and sediments through a slow process called weathering.

Phosphorus is often a limiting nutrient in ecosystems due to its slow release and movement.

Phosphorus is essential for all living organisms as it is a key element in ATP, DNA, and provides strength to bones and teeth.

Natural sources of phosphorus include the weathering of phosphorus-containing rocks by wind and rain.

Human-made sources of phosphorus come from mining phosphate rocks and adding them to fertilizers and detergents.

Phosphorus is absorbed by plants from the soil and assimilated into their tissues.

Animals obtain phosphorus by consuming plants or other animals that have eaten plants.

Decomposition of dead organic matter and excretion of animal waste return phosphorus to the soil.

Sedimentation is the process where phosphorus precipitates out of water and forms sediments at the bottom of bodies of water.

Geological uplift exposes new rock layers to weathering, continuing the phosphorus cycle.

Eutrophication is a problem caused by excess nitrogen and phosphorus in bodies of water, leading to algae blooms and oxygen depletion.

Eutrophication can create dead zones where low oxygen levels prevent the support of most aquatic life.

The practice skill involves using a visual model to explain the movement of phosphorus between reservoirs.

Transcripts

hey everybody it's mr smeeds and today

we'll be covering topic 1.6

which is the phosphorous cycle just like

with the carbon cycle and the nitrogen

cycle

we'll be talking about how phosphorus

moves between sources and sinks

but we'll also be making some

comparisons between the carbon cycle and

the nitrogen cycle

as we go through the phosphorus cycle

today our objective today is to be able

to explain the steps and reservoir

interactions

in the phosphorus cycle and the skill

we'll practice at the end of the video

is the one that we've been practicing

the past

couple days which is explaining

relationships between characteristics of

an environmental concept

in a visual model setting so just like

in the carbon cycle in the nitrogenous

cycle

the phosphorus cycle is the movement of

phosphorus containing

elements between sources and sinks

so the two major reservoirs of

phosphorus are rocks

and phosphorus containing sediments

so if we look at the diagram here we can

see rocks that could be found in

mountains or really in any ecosystem

contain phosphorus in them and also

sediments at the bottom of bodies of

water

or even sediments found in soil an

important point to know is that the

phosphor cycle is extremely slow

when compared to the carbon cycle and

nitrogen cycle this is for a couple

reasons which we'll talk about now

so the first one is that the two main

reservoirs of phosphorus which again are

rocks and sediments

release phosphorus very slowly it's a

process called

weathering where wind and rain break

down the rock

and release phosphorus in a form called

phosphate

so that phosphate then has to be washed

away from that rock or those sediments

and into either aquatic ecosystems or

into soil on land

so that process takes a long time

another reason that this is such a slow

process is there's no gas

form of phosphorus on earth and so what

that means

is that phosphorus has to be moving in

this solid form

in phosphate which has to be weathered

from rocks and carried by water

and that's just really slow so when we

compare that again to the nitrogen

carbon cycles

there are gas phases of both of those

cycles which move faster

then finally an important point to

understand is that because phosphorus

cycles so slowly

it's often a limiting nutrient in

ecosystems

so because it takes so long for the

rocks to be weathered and for them to

release their phosphorus which is then

carried through runoff into either

bodies of water or in the soil

that's a really slow process and

organisms therefore

have less access to phosphorus now all

organisms need

phosphorus because it's a key element in

atp

which is an energy source for every

living thing in dna

and then for many animals it's a source

of strength for their bones

and for the enamel in their teeth now

we'll talk about

both natural and synthetic sources of

phosphorus

so the major natural source of

phosphorus is the weathering of

phosphorus containing rocks

by the wind and the rain so the wind in

the rain beat down on these rocks over

time

breaking them into smaller bits which

results in the release of phosphate from

these rocks

the phosphate then dissolves into the

rainwater and it's washed either into

aquatic ecosystems

or into terrestrial ecosystems so into

the soil

in an area so you can see this here in

the diagram if we look at this big green

circle

again the phosphates are worn down from

those rocks and then the wind and the

rain will carry them either into a body

of water

or into a terrestrial ecosystem it's

important to remember that this process

is very slow

and because of that phosphorus is a

limiting nutrient in many different

ecosystems meaning plant growth is

dependent on how much phosphorus

is available in terms of synthetic or

human-made sources of phosphorus humans

mine

phosphate containing rocks out of the

ground and then they add phosphates to

either synthetic fertilizers or other

products like detergents and cleaners

so we can see this diagram here we'll

dig up rocks that contain

phosphorus take out the phosphorus and

add phosphates to these products such as

fertilizers or detergents

so this creates an issue because when we

have runoff from agricultural fields it

can carry the phosphates

that were in the soil into nearby bodies

of water

the same thing can happen if we're

talking about detergents and cleaners

because those can leave homes via their

waste water

and the phosphates in those detergents

and cleaners can eventually enter

natural bodies of water

just like nitrogen phosphorus is

absorbed from the soil by plant's roots

and it's assimilated into plant tissues

animals just like in the nitrogen cycle

have to eat plants to take in

phosphorus to their bodies or eat other

animals that have eaten plants

then we also have the excretion of

animal waste

or the decomposition of dead organic

matter by soil bacteria and decomposers

and that's going to return phosphorus to

the soil so

just like in the nitrogen cycle we have

this mini loop that's formed here

where we have assimilation of phosphorus

into plants

and then we have animals that eat those

plants to take the phosphorus into their

bodies

when the animals and plants die that

phosphorus is returned to the soil by

decomposition

just like in the nitrogen cycle next

we'll talk about sedimentation

and geological uplift so phosphorus does

not dissolve

super well into water which means that

much of it precipitates out or forms

solid phosphate sediments at the bottom

of a body of water

think about when you make kool-aid and

you add too much sugar

the water can only hold so much of that

sugar so a lot of it forms crystallized

sugar at the bottom that you can

actually see

and so this is similar to the way that

phosphate will precipitate out of a

water source

and we call this act sedimentation so

the act of

forming phosphate sediments at the

bottom of a body of water

over time what we can see is that the

weight of the water

above those phosphate containing

sediments will compress those sediments

into sedimentary rock like limestone or

sandstone

geological uplift then is the process

where tectonic plates collide

and force new rock layers up to form

mountains

so this allows new rock to be exposed to

the elements like wind and rain

which then starts the weathering of

phosphorus and we're basically back at

the beginning of the cycle

and lastly today we'll talk about a

problem called eutrophication

which results when a body of water

receives too much nitrogen and

phosphorus

so because these elements are usually so

limited

having extra inputs of nitrogen or

phosphorus can lead to eutrophication

which literally means excess growth or

excess nutrients

and this can in turn lead to an algae

growth or an algae bloom

that covers up the surface of the water

now these nitrogen

inputs can often come from things like

synthetic fertilizers

that are applied to lawns or

agricultural fields or

when a body of water becomes

contaminated with

waste from humans or waste from animals

because this waste is an organic

compound

they often contain both phosphorus and

nitrogen

so because the surface of the water is

covered by these algae

that blocks the sunlight from reaching

the plants below the surface of the

water

and those plants die the algae

themselves

eventually die off and then the bacteria

in the water use up oxygen to break down

the algae and the other dead plants

the reason that they use up the oxygen

is because decomposition

is an aerobic process so it requires

them to use oxygen

this loss of oxygen as the bacteria use

it up

results in the death of other aquatic

species especially larger fish species

that have high oxygen requirements then

the bacteria break down those dead

organisms

and that uses up even more oxygen so

pretty quickly we have something called

a positive feedback loop

positive feedback loop is where the

outcome of the process

drives the process to continue forward

at an even faster rate

so as we have less oxygen we have more

organisms die

which results in more bacteria breaking

down those dead bodies

using up even more oxygen and you can

see how this quickly spirals out of

control

to create something called a dead zone

where the water contains such little

oxygen

that virtually no life can be supported

there anymore

our practice frq for topic 1.6 today

will involve the skill

of using a visual model to explain

relationships between different

characteristics of an environmental

concept

so i want you to look at this model and

choose two reservoirs that are shown in

the model

then i want you to describe how

phosphorus

moves between those two reservoirs

alright everybody

thanks for tuning in today don't forget

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