Nutrient cycles

The 'nutrient cycles in nature are often called 'BIOGEOCHEMICAL CYCLES' BIO – life GEO - planet CHEMICAL - non-organic materials in other words, these nutrients cycle through living and non-living aspects of our environment. In

thinking about the Carbon-Oxygen cycle you can see this. Carbon can be found in both living things

and in non-living ones (carbonates in ocean water, or carbon in the fossil fuels of oil, coal and

natural gas)! **************************** NUTRIENT / natural CYCLES in brief Any chemical element or compound an organism must take in to live, grow, or reproduce is called a

nutrient. Some elements such as carbon, oxygen, hydrogen, nitrogen, and phosphorus are needed in

fairly large amounts. Others such as iron, copper, chlorine, and iodine are needed in small (trace)

amounts. These nutrient elements and their compounds are continuously cycled form the nonliving

environment (air, water, soil) to living organisms and then back to the nonliving environment in what

are called nutrient cycles (biogeochemical cycles - the $10 word - or life-earth-chemical

cycles - the 5 cent word!). These cycles are driven by incoming solar energy and gravity. Earth's chemical cycles connect past, present and future forms of life. This system is closed and

these materials cannot be lost but can end up outside the reach of living things. Thus, some of the

carbon atoms in the skin or your right hand may once have been part of a leaf, a dinosaur's skin, or

a layer of limestone rock. And some of the oxygen molecules you just inhaled may have been inhaled

by your grandmother, by Plato or by a hunter-gatherer who lived 25,000 years ago. Natural cycles include water, some gases (like Oxygen and Carbon Dioxide) and certain chemicals

(elements) like carbon, phophorus, and nitrogen (all of these could be called NUTRIENTS) - are

constantly being exchanged between air, water, soil, plants and animals. The number of plants and

animals in an ecosystem must stay in balance to survive. Competing for food, water, light, and other

resources is one way plant and animal numbers stay in balance. This balance is called homeostasis!

(ho-me-o-stay-sus)

Biogeochemical Cycles

As a part of biogeochemical cycles, certain elements move through both living and non-living

components of the Earth system. The living parts of the Earth system comprise the biosphere,

while the non-living parts of the Earth include the hydrosphere, atmosphere, cryosphere, and

geosphere. The same individual elements are recycled over and over in different parts of the

Earth through biogeochemical cycles.

For example, carbon may be taken from the air (atmosphere) into the ocean surface

(hydrosphere) where it is utilized by photosynthesizing plankton (biosphere). Carbon is also

stored long-term in rocks (geosphere) and fossil fuels like oil, coal, and natural gas (biosphere).

This long-term storage that sequesters an element from the rest of the cycle for some amount of

time is called a “sink”. When fossil fuels are burned, carbon that had been sequestered

underground is sent into the air (atmosphere) as carbon dioxide, a greenhouse gas.

All chemical elements that are found in living things are a part of biogeochemical cycles, the

most common of these being carbon and nitrogen.

Find out more about 2 common biogeochemical cycles (info on each is further down below too!)

The carbon cycle

The nitrogen cycle

In recent decades these biogeochemical cycles have been changing because of how humans are

changing the biosphere (see links below). Less forests, more factories and cars that burn fossil

fuels - these changes to biogeochemical cycles are causing more greenhouse gases in our

atmosphere and, thus, more global warming.

THE WATER (or hydrologic) CYCLE:

The Sun heats water in soil, rivers, lakes & oceans, causing it to evaporate & become water vapor (a

gas)

+ water vapor rises, cools and condenses to form tiny water droplets or ice crystals in clouds.

+ This water falls back to earth as rain, snow or other precipitation + Most water returns to the sea or sinks into underground water sources. + Plants take water up from the soil through their roots. They transpire most of the water they

take up (TRANSPIRATION is when water passes through the plants and out the stoma on the

underside of the leaves. The water then evaporates into the air.) + water makes up almost 75% of the bodies of living things and this is where bacteria, protistians,

fungi, and animals become part of the cycle + when things decompose, water is released.

This cycle collects, purifies, and distributes Earth's fixed supply of water. The main processes in

this water recycling and purifying cycle are evaporation (conversion of water into water vapor),

transpiration (evaporation of water extracted by roots and transported upward form leaves or

other parts of plants), condensation (conversion of water vapor into droplets of liquid water),

precipitation (dew, rain, sleet, hail, snow), infiltration (movement of water into soil), percolation

(downward flow of water through soil and permeable rock formations to groundwater storage

areas), and runoff down slope back to the sea to begin the cycle again. At different phases of the

cycle water is stored for varying amounts of time on the planet's surface (oceans, streams,

reservoirs, glaciers) or in the ground.

All life depends on the presence of water. The bodies of most organisms are made of it. Water is

the source of H ions whose movements generate ATP (adenosine triphosphate) in organisms. ATP

aids in energy transfers within organisms and is necessary to life.

The water cycle is the most familiar to us. Water covers about 3/4 of the earth's surface. From

that surface it evaporates into the atmosphere, powered by energy from the sun. This water

eventually precipitates back to earth and passes into surface and subsurface bodies of fresh

water. Most falls directly into oceans but some falls onto the earth. About 2% of water on earth is

unavailable to life (frozen, held in soil, incorporated into the bodies of organisms). All the rest is

free water, circulating between the atmosphere and earth. Less obvious are subsurface waters found in permeable, saturated, underground layers of rock,

sand, and gravel called aquifers. In many areas, underground water is the most important reservoir

of water. It is 96% of all fresh water in the U.S. It flows slower than surface water and is

replenished more slowly. Its use is growing much more rapidly than the use of surface water. We intervene in the water cycle in two main ways: 1. By withdrawing large quantities of fresh water from streams, lakes, & underground. In heavily

populated or heavily irrigated areas, withdrawals have led to groundwater depletion or intrusion of

ocean salt water into underground water supplies. 2. By clearing vegetation from land for agriculture, mining, roads, construction, and other

activities. This reduces seepage, which recharges groundwater supplies. This reduction also

increases the risk of flooding and speeds surface runoff, producing more soil erosion and landslides.

---THE WATER CYCLE

QUESTIONS

1. What provides the energy to 'run' the water cycle?

2. Where on earth does most precipitation fall?

3. Is there a starting point to the water cycle? An end point? Explain. ????

WATER CONTINUED…

Water is always on the move. Rain falling where you live may have been water in the ocean just days

before. And the water you see in a river or stream may have been snow on a high mountaintop.

Water can be in the atmosphere, at the Earth surface, and even underground. It is recycled over

and over through the water cycle. In the cycle, water changes state between liquid, solid (ice), and

gas (water vapor).

There are a number of ways that water vapor gets into the atmosphere. Through the process of

evaporation some of the liquid water that is at the top surface of the ocean, rivers, and lakes

becomes water vapor in the atmosphere. This is the most common way that water vapor forms.

Water vapor can also form from snow and ice through the process of sublimation and can be formed

by plants through the process of transpiration.

The water vapor rises in the atmosphere and cools forming little water droplets in the atmosphere

through the process of condensation. Those water droplets make up clouds. If those tiny water

droplets combine with each other, growing larger in size, they will grow too heavy to stay in the air

and will fall to the ground as precipitation. Some precipitation falls as rain, and some falls as snow

and ice, depending on the temperature of the atmosphere.

Most of the precipitation that falls becomes a part of the ocean or it becomes part of rivers, lakes,

and streams that eventually lead to the ocean. Some of the snow and ice that falls as precipitation

stays at the Earth surface in glaciers, ice sheets, and snowfields for some time. Some of the

precipitation seeps into the ground and becomes a part of the groundwater.

Water stays in certain places longer than others. A drop of water may spend over 3,000 years in

the ocean before moving on to another part of the water cycle while a drop of water spends an

average of just eight days in the atmosphere before falling back to Earth.

CARBON-OXYGEN CYCLE This cycle is based upon carbon dioxide (only 0.03% by volume of the atmosphere and it is also

dissolved in water.). We get it from photosynthesis and chemosynthesis when plants and bacteria

remove it from the air and or water and 'fix ' it - that is incorporate it into complex

carbohydrates, like glucose, for fuel. This fuel is used by the producer who first made them, by a

consumer or decomposer that has consumed or decomposed the producer. When it is used the

carbon dioxide is once again set free into the atmosphere or in water for reuse by producers. The link between photosynthesis in producers and aerobic respiration in producers and consumers

circulates carbon in the ecosphere and is a major part of the global carbon cycle. Oxygen and

hydrogen, the other elements in carbohydrates, cycle almost in step with carbon.

+ Living things are composed mainly of complex molecules containing carbon. + Carbon and oxygen make up the gas Carbon dioxide. Plants take IN this gas during photosynthesis + Plants use it to MAKE FOOD during the process. +This food provides matter (nutrients) and energy to form new plant cells. +During photosynthesis, plants also release oxygen (a by product or result of photosynthesis) into

the air. + Both animals and plants take in Oxygen during RESPIRATION

1. THINK how do plants get it in their systems? How do animals?????

RESPIRATION is the breaking down of food so its' energy can be used. In this process, cells - of

plants OR animals OR other living things – use oxygen from the air to release stored food energy.

Carbon Dioxide and water are products of (given off) during respiration. +So, both plants and animals (and other living things) give off Carbon Dioxide during respiration.

2. How do plants get rid of this carbon dioxide? How do animals????

+ Detritivores which are decomposing dead plants & animals also produce carbon dioxide as they

respire (decay/breakdown dead stuff). + Some carbon (ancient dead plants & animals) was stored as fossil fuels (coal, oil, & natural gas)

Some carbon is out of reach of living things. Coal beds and sea-bed deposits or marine organisms

shells (made of calcium carbonate). Carbon is also released into the atmosphere through natural

causes (volcanoes), and through human actions (combustion). The natural release of carbon dioxide

takes thousands of years. The release of carbon from fossil fuels (a human activity) appears to be

changing global climates. This greater amount of carbon in the atmosphere traps the longer

wavelengths of infrared light (heat) an prevents them from radiating into space. By doing so it

creates the greenhouse effect that raises the overall temperature of earth and atmosphere.

Especially since 1950, as world population and resource use have soared, we have disturbed the

carbon cycle in two ways that add more carbon dioxide to the atmosphere than oceans and plants

can remove: 1. Forest & brush clearing, leaving less vegetation to absorb CO2. 2. Burning fossil fuels & wood, which puts CO2 into the atmosphere.

1. What roles do plants play in this cycle????

2. How do humans affect this cycle????

3. Describe the role of producers in this cycle. ???

4. What role do animals play in this cycle????

5. Explain the relationship between cellular respiration & photosynthesis.???

6. Describe the role of Carbon Dioxide in the Carbon Cycle.???

The Earth's atmosphere keeps the planet warm by a process called THE GREENHOUSE EFFECT.

It lets in the sun's energy in the form of visible light. When this light hits the earth, it becomes

heat. Greenhouse gases let some of this heat back into space, but they trap some within the

atmosphere. This (up to a point) is a good thing. It helps shield us (living things) from BAD

ultraviolet rays AND helps regulate our climate on Earth. :0) Burning fossil fuels (coal, oil, natural gas) or wood adds more greenhouse gases (like CO2) to the

atmosphere. As we burn more and more, some folks think the increase in the amount of greenhouse

gases may lead to an increase in the world's temperature. They call this GLOBAL WARMING.

The concern is that this increased heat could change weather patterns and in the long run, harm

life on Earth. Keep in mind, however, the Earth's atmosphere and climate are complicated, and no

one can be sure how much the atmosphere might warm or how much harm that could

do...Humm...Info on other cycles: There are many mineral and elements that are the building blocks for all life. In an ecosystem,

these minerals and elements flow from one form to another as they are used by living organisms and

then recycled for use again. In these cycles, these elements and minerals are in the atmosphere, in

water, or in soil, and rock. These nutrients are also absorbed and used by organisms in the

processes of metabolism and respiration to form the complex organic molecules needed for life.

This flow/movement is called the nutrient or biogeochemical (bio-living, geo-earth, and chemical -

the substances that are being cycled) cycle and is natures' way of using and re-using the earth's

natural resources to support life.

THE CARBON CYCLE

NITROGEN CYCLE (bacteria in action!) Nitrogen gas is about 80% of our atmosphere by volume, but the total amount fixed in the soil,

oceans and bodies of organisms is tiny in comparison. Atmospheric nitrogen cannot be directly used

by most organisms (multi-celled plants and animals) because they do not have the ability to convert

it into usable form. Fortunately there are several types of bacteria which convert nitrogen gas into

water-soluble compounds containing nitrogen. This can then be readily absorbed by plant roots.

This is part of the Nitrogen Cycle. The conversion of atmospheric nitrogen gas into other chemical forms useful to plants is called

NITROGEN FIXATION. It is done mostly by cyanobacteria in soil and water and by Rhizobium bacteria living in small nodules (swellings) on the roots of alfalfa, clover, peas, beans and other

legumes. These bacteria live in mutualistic relationship with the plants. Once 'fixed', nitrogen is

able to cycle within biological systems. Atmospheric nitrogen can be fixed by high temperatures, causing it to combine with oxygen to form

nitrogen oxide. This can combine with water to form nitrates. Combustion, volcanic action and

lightning discharge are ways this can be accomplished. Without nitrogen organisms could not synthesize proteins, nucleic acids, and other nitrogen

containing compounds. Nitrogen fixation makes nitrogen available for biological processes. After

nitrogen has served its purpose in living organisms, armies of specialized decomposer bacteria

convert the complex, nitrogen rich compounds, wastes, cast off particles, and dead bodies of

organisms into simpler nitrogen containing compounds. Other specialized bacteria then convert

these forms into nitrogen gas that is released to the atmosphere to begin the cycle again. Some ways we intervene in the nitrogen cycle are: 1. Emitting large quantities of nitric oxide (NO) into the atmosphere when any fuel is burned.

(Most NO is produced when nitrogen & oxygen molecules in the air combine at high temperatures)

This nitric oxide combines with oxygen to form nitrogen dioxide (NO2) gas, which can react with

water vapor to form nitric acid (HNO3). This acid is a component of acid deposition (acid rain),

which can damage trees & upset aquatic ecosystems. 2. Emitting heat-trapping nitrous oxide (N2O) gas into the atmosphere by the bacteria on

livestock wastes and commercial inorganic fertilizers applied to the soil. 3. Mining nitrogen-containing mineral deposits for fertilizers. 4. Depleting nitrogen from soil by harvesting nitrogen-rich crops. 5. Adding excess nitrogen compounds to aquatic ecosystems in agricultural runoff and discharge

of municipal sewage. This excess of plant nutrients stimulates rapid growth of cyanobacteria,

algae, and aquatic plants. The subsequent breakdown of dead algae by aerobic (with oxygen)

decomposers depletes the water of dissolved oxygen gas and can disrupt aquatic ecosystems.

The Nitrogen Cycle

Nitrogen is an element that is found in both the living portion of our planet and the inorganic parts

of the Earth system. The nitrogen cycle is one of the biogeochemical cycles and is very important

for ecosystems. Nitrogen moves slowly through the cycle and is stored in reservoirs such as the

atmosphere, living organisms, soils, and oceans along its way.

Most of the nitrogen on Earth is in the atmosphere. Approximately 80% of the molecules in Earth's

atmosphere are made of two nitrogen atoms bonded together (N2). All plants and animals need

nitrogen to make amino acids, proteins and DNA, but the nitrogen in the atmosphere is not in a form

that they can use. The molecules of nitrogen in the atmosphere can become usable for living things

when they are broken apart during lightning strikes or fires, by certain types of bacteria, or by

bacteria associated with legume plants. Other plants get the nitrogen they need from the soils or

water in which they live mostly in the form of inorganic nitrate (NO3-). Nitrogen is a limiting factor

for plant growth. Animals get the nitrogen they need by consuming plants or other animals that

contain organic molecules composed partially of nitrogen. When organisms die, their bodies

decompose bringing the nitrogen into soil on land or into the oceans. As dead plants and animals

decompose, nitrogen is converted into inorganic forms such as ammonium salts (NH4+ ) by a process

called mineralization. The ammonium salts are absorbed onto clay in the soil and then chemically

altered by bacteria into nitrite (NO2-) and then nitrate (NO3- ). Nitrate is the form commonly used

by plants. It is easily dissolved in water and leached from the soil system. Dissolved nitrate can be

returned to the atmosphere by certain bacteria in a process called denitrification.

Certain actions of humans are causing changes to the nitrogen cycle and the amount of nitrogen

that is stored in reservoirs. The use of nitrogen-rich fertilizers can cause nutrient loading in

nearby waterways as nitrates from the fertilizer wash into streams and ponds. The increased

nitrate levels cause plants to grow rapidly until they use up the nitrate supply and die. The number

of herbivores will increase when the plant supply increases and then the herbivores are left without

a food source when the plants die. In this way, changes in nutrient supply will affect the entire food

chain. Additionally, humans are altering the nitrogen cycle by burning fossil fuels and forests, which

releases various solid forms of nitrogen. Farming also affects the nitrogen cycle. The waste

associated with livestock farming releases a large amount of nitrogen into soil and water. In the

same way, sewage waste adds nitrogen to soils and water.

THE NITROGEN CYCLE

PHOSPHORUS CYCLE Phosphates (charged phosphorus ions) exist in small amounts in the soil and large amounts in rock.

This phosphorus moves through water, the Earth's crust and living organisms in the Phosphorus

Cycle. Unfortunately phosphorus ions are fairly insoluble (won't dissolve in water) and when they do

dissolve they are most often washed into the sea and deposited permanently on the sea floor where

they are not available for use.

Phosphorus moves slowly from phosphate deposits on land and shallow ocean sediments to living

organisms, and them back to the land and ocean. Bacteria (that decompose) are less important in

the cycling of this nutrient than in the Nitrogen Cycle. Also, unlike nitrogen, phosphorus does not

circulate in the atmosphere. Phosphorus in the soil is taken in by plant roots in the form of

inorganic phosphates . Animals obtain this inorganic or organic compound in the food they eat

(ultimately derived form plants). Animals and plants use phosphorus in the manufacture of ATP

(Adenosine Triphosphate Phosphate). ATP boosts cell activity and allows them to function properly Two chief ways we intervene in the phosphorus cycle: 1. Phosphorus enters aquatic communities through absorption by algae and plants, which are in

turn consumed by large organisms and by microorganisms and other plankton. These are then eaten

by various fin and shell fish, which may also feed upon one another. These body parts eventually

wind up on the sea floor or in marine bird droppings. Adding excess phosphorus to aquatic

ecosystems in runoff of animal wastes from livestock feedlots, runoff of commercial phosphate

fertilizers from cropland, and discharge of municipal sewage causes explosive growth of

cyanobacteria, bacteria and aquatic plants. This throws aquatic ecosystems out of 'balance' and

disrupts life there. 2. Mining phosphate rock to produce commercial inorganic fertilizers and detergents.

WE WILL NOT COVER THIS ONE IN CLASS – BUT fyi….

THE ROCK CYCLE - sometimes called ROCK/SOIL CYCLE

Geologic processes redistribute the chemical elements within and at the surface of the earth.

Based on the way it forms, rock is placed in three broad classes: igneous, sedimentary or

metamorphic. Igneous forms when molten rock material (magma) wells up from Earth's upper mantle or deep

crust, cools, and hardens into rock. Examples are granite (formed underground) and lava rock

(formed above ground when molten lava cools and hardens). Sedimentary forms from accumulated products of erosion of preexisting rock and, in some cases,

from the compacted shells, skeletons, and other remains of dead organisms. As these deposited

layers become buried and compacted, the resulted pressure causes their particles to bound

together to form sedimentary rocks such as shale, limestone, and lignite and bituminous coal. Metamorphic is produced when a preexisting rock is subjected to high temperatures (which may

cause it to melt partially), high pressures, chemical active fluids, or a combination of those agents.

Examples are anthracite (a form of coal), slate and marble. Rocks are constantly being exposed to various physical and chemical conditions that over time can

change them. The interaction of processes that change rocks form one type to another is called

the rock cycle. Recycling materials over millions of years, this slowest of Earth's cyclic processes

is responsible for concentrating mineral resources on which humans depend.

ROCK CYCLE

Carbon Cycle (REVISITED)

The element Carbon has the ability to cycle globally, due to its atmospheric reservoir. In the Carbon Cycle, carbon dioxide (CO2) from the atmosphere is absorbed by plants through photosynthesis, then returned to the atmosphere via cellular respiration. In more depth, carbon dioxide in the atmospheric reservoir is taken in by plants in order to complete photosynthesis. The plants then serve two purposes: they produce oxygen (O2) and they become food for primary consumers. The oxygen in the air is breathed in by all organisms as part of cellular respiration, which returns carbon dioxide to the atmosphere. The plant food eaten by the primary consumers contains carbon, which is passed up through the trophic pyramid to all levels of consumers. In addition, dead material containing carbon is decomposed and eaten by detritivores, another part of the food chain. imbalance in nitrogen cycle A big problem we have going on right now is the extra emission of carbon dioxide from the burning of fossil fuels in factories, automobiles, etc. This increases the level of CO2 in the atmosphere, thus throwing the entire cycle off balance. Abiotic reservoirs: atmosphere, soil Biotic reservoirs: plants, animals, detritivores

Nitrogen Cycle (Revisited)

The element Nitrogen also has the ability to cycle globally, because of its presence in the atmosphere. Nitrogen in the atmosphere is only found in the form N2. Only very few creatures can take in nitrogen in this form. Therefore, nitrogen-fixing bacteria in the soil take on the task. The bacteria come in two types: free bacteria and root nodule bacteria. Free bacteria survive on their own in the soil. These bacteria carry out the chemical reaction that changes N2 to ammonium (NH4+), called Nitrogen Fixation. Ammonium and nitrate (NO3-), another form of nitrogen, can be used by most plants and are found in Amino Acids. Nitrates come from nitrifying bacteria in the soil, which take in ammonium to create nitrates (called nitrification). These nitrates, in addition to supplying Amino Acids to plants, return to the atmospheric reservoir through a process called, incidentally, denitrification. Finally we get to root nodule bacteria. These bacteria supply legumes, or pod-producing plants, with nitrogen that they cannot recieve on their own. This is a commensalistic relationship, because the bacteria do not benefit, but the legumes could not possibly survive without them. Another process in the Nitrogen Cycle is the decomposition of animals. As stated before, animals cannot absorb N2 on their own, so they must rely on the plants they eat (or lower level consumers) to get nitrogen. When these animals die, the nitrogen stays within them, as does Carbon, and detritivores transform it into ammonium, thus continuing the cycle. Abiotic reservoirs: atmosphere, soil Biotic reservoirs: animals, plants, detritivores, bacteria

Phosphorus Cycle (revisited)

Unlike the two cycles we have seen before, the Phosphorus Cycle is local, as opposed to global. This means that phosphates do not travel out of their ecosystem, because their main abiotic reservoir is in rocks. Also, the cycle mainly takes place in rocks. When rain falls on a rock, phosphates travel down the runoff and into nearby bodies of water, where they become solutes. They then separate, along with other sediments, to form precipitated, or solid, phosphates on the riverbed. They then travel up the rocks all the way to the tops of mountains, where they eventually join the runoff. All these examples of phosphates are inorganic (white boxes). However, the Phosphorus Cycle is also organic (yellow boxes). Not all phosphates in the runoff make it to the water; others simply sink into the soil. These inorganic phosphates are transformed into organic ones by plants, which are in turn eaten by animals. The dead animals, as seen with nitrogen and carbon, retain their internal phosphorus stores, and, as before, detritivores change the organic phosphates back to inorganic ones. Abiotic reservoirs: rocks, water Biotic reservoirs: organisms (DNA)