46.3 Biogeochemical Cycles

PCB concentrations increased from the primary producers (phytoplankton) through the different trophic levels of fish species, as shown in a study performed by the National Oceanic and Atmospheric Administration.

The amount of PCBs in the walleye is four times greater than in the phytoplankton.
Birds that eat these fish may have PCB levels that are at least one order of magnitude higher than those found in the lake fish.

The PCB concentrations are shown in the chart.

There are numbers on the x-axis that show enrichment with heavy nitrogen (15N) which is a marker for increasing trophic level.

The fish in higher trophic levels accumulate more PCBs than the fish in lower trophic levels.

Heavy metals, such as mercury and cadmium, can accumulate in certain types of seafood.

The EPA recommends that pregnant women and young children not eat swordfish, shark, king mackerel, or tilefish because of their high mercury content.
Salmon, tilapia, shrimp, pollock, and catfish are low in mercury and should be eaten by these individuals.
A good example of how ecology can affect our lives is biomagnification.

By the end of this section, you will be able to discuss the biogeochemical cycles of water, carbon, nitrogen, phosphorus, and sulfur.

The matter that makes up living organisms is recycled.
Carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur can be found in a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath the Earth's surface.
weathering, erosion, water drainage, and the subduction of the continental plates all play a role in this recycling of materials.

Oxygen and hydrogen are essential to all living processes.

Water is in the atmosphere.
Carbon is an important component of fossil fuels.
Nitrogen is critical to human agriculture and is a major component of our nucleic acids.
One of the main ingredients in artificial fertilizers used in agriculture and their associated environmental impacts on our surface water is Phosphorus, a major component of nucleic acid.

The elements are interdependent.

The movement of water is important for the removal of nitrogen and phosphate from the water.
The ocean is a major source of carbon.
The entire biosphere, from one living organisms to another, and between the biotic and abiotic world, is home to mineral nutrients.

There is a link to learn more about biogeochemical cycles.

The basis of all living processes is water.

Almost all of the water on Earth is non-potable.
99 percent of the water is locked underground.
Less than 1 percent of fresh water is easily accessible.
A lack of fresh surface water can have huge effects on the ecology of living things.
The organisms have to adapt to changing water supplies.
Humans have developed technologies to increase water availability, such as digging wells and using desalination to get water from the ocean.

Less than 1 percent of fresh water is easily accessible to living things, and only 2.5 percent of water on Earth is fresh water.

Water cycling is important to the ecology.

Water has an influence on the environment.
The oceans, underground, and as ice hold most of the water on Earth.

The average residence time for water in the Earth's water is shown in the graph.

The water cycle is driven by the sun's energy as it warms the oceans and other surface waters.

Large amounts of water vapor are deposited into the atmosphere when liquid surface water and frozen water are combined.
Over time, this water vapor condenses into clouds as liquid or frozen droplets and is eventually followed by precipitation, which returns water to the Earth's surface.
If rain is near the surface, it may evaporate, if it is beneath the surface, or if it is stored for a long time.
The flow of fresh water from rain or melting ice can be easily observed.
Runoff can travel through streams and lakes to the ocean.

There is a link to learn more about the world's fresh water supply.

Minerals, including carbon, nitrogen, phosphorus, and sulfur, are cycled from land to water through rain and surface runoff.

As these cycles are described, the environmental effects of runoff will be discussed.

Water from the land and oceans enters the atmosphere when it condenses into clouds and falls as rain or snow.

Precipitated water can enter freshwater bodies.
When the ocean reenters the cycle is complete.
The second most abundant element is carbon.
The structure of macromolecules is important to living organisms because of the presence of carbon.

There are two sub-cycles of the carbon cycle, one dealing with rapid carbon exchange among living organisms and the other with the long-term cycling of carbon through geologic processes.

Carbon dioxide is dissolved in water.

When matter from living organisms is buried deep underground and becomes fossils, long-term storage of organic carbon occurs.
The carbon cycle is brought back into action by volcanic activity and human emissions.

There are many ways in which living organisms are connected.

An example of this connection is the exchange of carbon between autotrophs and Heterotrophs by way of atmospheric carbon dioxide.

These organisms use the sun's energy to form bonds of carbon atoms.

The chemical bonds store the energy for later use.

Oxygen is a by-product of the process.

The oxygen content of the atmosphere is deposited by the photosynthetic organisms.

The primary consumers of biological carbon exchange are Heterotrophs and autotrophs.

Heterotrophs acquire the high-energy carbon compounds from the autotrophs by consuming them, and breaking them down by respiration to obtain cellular energy.

Aerobic respiration requires oxygen to be obtained from the atmosphere or dissolved in water.
There is a constant exchange of oxygen and carbon dioxide between the autotrophs and the Heterotrophs.
The carbon cycle is connected by gas exchange through the atmosphere and water.

The movement of carbon through the land, water, and air is very complex and takes a long time.

Carbon is stored in a number of places, including the atmosphere, bodies of liquid water, ocean, soil, land, and fossil fuels.

The atmosphere is a major source of carbon in the form of carbon dioxide and is essential to the process of photosynthesis.

The amount of carbon dioxide in the atmosphere is influenced by the amount of carbon in the oceans.
The amount of carbon found in each location is influenced by the exchange of carbon between the atmosphere and water.

Water reacts with carbon dioxide.

The equilibrium coefficients show that more than 90 percent of the carbon in the ocean is found in the form of bicarbonate ion.

CaCO3 is a major component of marine organisms and is formed by some of these ion and seawater calcium.

The organisms form on the ocean floor.

The largest carbon repository on Earth is formed by the calcium carbonate.

Carbon is stored in the soil as a result of the decay of living organisms or weathering of rock and minerals.

The carbon can be recycled into water.
Fossil fuels are the remains of plants that take millions of years to form.
Fossil fuels are considered nonrenewable because of their use.
Land beneath the surface of the ocean can be used as a conduit for carbon to enter the atmosphere.
Carbon dioxide is released when a volcano erupts.

Fossil fuels and other materials are burned by humans.

Humans have increased the release of carbon and carbon compounds, which has affected the climate and overall environment.

Humans increase atmospheric carbon.

The large numbers of land animals raised to feed the Earth's growing population results in increased carbon dioxide levels in the atmosphere due to farming practices.
This is an example of how human activity can affect biogeochemical cycles.
Scientists take natural processes, such as volcanoes and respiration, into account as they model and predict the future impact of increasing atmospheric carbon on climate change.

Nitrogen is hard to get into the living world.

Even though triple covalent N2 is found in 78 percent of the atmosphere, plants and phytoplankton are not able to incorporate it.
Nitrogen enters the living world via free-living and symbioticbacteria, which incorporate nitrogen into their macromolecules.
Nitrogen fixation is a key role of the cyanobacteria in most aquatic environments.
Nitrogen can be "fix" by the cyanobacteria.

Pea, beans, and peanuts are provided with organic nitrogen by Rhizobiumbacteria, which live in the root nodules of the legumes.

Azotobacter is one of the important nitrogen fixers.

Primary production and decomposition are limited by the available supply of nitrogen, which is why it is important to study organic nitrogen.

Ammonification, nitrification, and denitrification are the three steps in the process.

First, the ammonification process converts nitrogenous waste from living animals or from the remains of dead animals into ammonium by certain bacteria and fungi.
The NO2 is converted to ammonium through nitrification.
Similar organisms convert nitrites to nitrates.
The process of denitrification happens when the nitrates are converted into nitrogen gas bybacteria.

Nitrogen enters the living world from the atmosphere.

This nitrogen and nitrogenous waste from animals is then processed back into gaseous nitrogen by soilbacteria, which in turn supplies the land with organic nitrogen they need.

Nitrogen can be released into the environment by two primary means: the burning of fossil fuels, which releases nitrogen oxides, and the use of artificial fertilization, which washes nitrogen into lakes, streams, and rivers.

Acid rain, HNO3 and greenhouse gas are all associated with atmospheric nitrogen and could be causing climate change.

In the marine nitrogen cycle, the ammonification, nitrification, and denitrification processes are performed by marinebacteria.

Some of the nitrogen falls to the ocean floor, which can be moved to land by the Earth's surface.
Although the movement of nitrogen from rock directly into living systems has been seen as insignificant compared with nitrogen fixed from the atmosphere, a recent study showed that this process may indeed be significant and should be included in any study of the global nitrogen cycle.

It is an essential component of living processes and makes up the supportive components of our bones.

In aquatic environments, the limitation of Phosphorus is necessary for growth.

The Phosphor ion is found in nature.

Natural surface runoff is a result of human activity and occurs when it is washed away by weathering.
The rock is from the ocean.
The bodies of ocean organisms and their excretions form the majority of the ocean sediments.
In remote regions, volcanic ash, aerosols, and mineral dust may be significant sources ofphosphate.
The uplifting of areas of the Earth's surface moves the land over geologic time.

In the ocean and marine environments, the exchange of Phosphorus is reciprocated.

The average time it takes forphosphate to move from the ocean to the land is between 20,000 and 100,000 years.

Weathering of rocks and volcanic activity releasesphosphate into the soil, water, and air, where it becomes available to food webs.

The oceans are affected by surface runoff, groundwater flow, and river flow.
The ocean water hasphosphate dissolved in it.
The ocean floor is where the marine food webs fall.
Dead zones in lakes and at the mouths of many major rivers are caused by this process.

Dead zones occur when excessive growth of organisms depletes oxygen and kills fauna.

Large dead zones are found in coastal areas.

More than 400 dead zones were present as of 2008, and the number of dead zones has been increasing for several years.

There is a dead zone of over 8500 square miles off the coast of the United States in the Gulf of Mexico.
Several lake and bay environments, including the Chesapeake Bay in the eastern United States, are negatively affected by nitrates andphosphates fromfertilizers.

The satellite image shows the environment of the bay.

A member of the Army Corps of Engineers is holding a clump of oysters.

The Chesapeake Bay is one of the most scenic areas on the planet and it is now in distress.

In the 1970s, the bay was one of the first to identify dead zones, which continue to kill many fish and bottom-dwelling species.
The decline of several species in the bay is due to excess nitrogen in the water.
The source of thefertilizer is not limited to agricultural practices.
There are more than 150 rivers and streams that are empty into the bay that are carryingfertilizer from lawns and gardens.
The decline of the bay requires the cooperation of industry, agriculture, and everyday homeowners.

More than 200,000 acres of oyster reefs existed in the bay in the 1700s, but the number has now declined to only 36,000 acres.

Between 1982 and 2007, oyster harvesting declined by 88 percent.
The decline was due to overharvesting.
Oysters need a certain minimum population density to reproduce.
The oyster population and locations have been altered by human activity.

The restoration of the oyster population in the bay has been a mixed success.

Many people find oysters good to eat and clean up the bay.
Oysters clean the water around them as they eat.
In the 1700s, it was estimated that it took only a few days for the oyster population to filter the entire bay.
It is estimated that the current population would take nearly a year to do the same job.

Restoration efforts have been going on for several years.

The goal is to increase population density so oysters can reproduce more efficiently.

The Virginia Institute of Marine Science for the College of William and Mary has developed many disease-resistant varieties that have been used in the construction of oyster reefs.
Efforts to clean and restore the bay by Virginia and Delaware have been hampered because much of the pollution entering the bay comes from other states.

The new oyster strains have spawned a new and economically viable industry which supplies oysters for food and profit, but also has the added benefit of cleaning the bay.

The macromolecules of living things have sulfur as an essential element.

It is involved in the formation of disulfide bonds within proteins, which help to determine their 3-D folding patterns, and hence their functions.
Sulfur dioxide is found in the form of sulfur dioxide and enters the atmosphere in three ways: from the decomposition of organic molecule, from volcanic activity and from the burning of fossil fuels by humans.

When sulfur dioxide is dissolved in precipitation as weak sulfurous acid or when it falls directly to the Earth, it becomes available to the marine andterrestrial environments.

Sulfates are made available to the ecosystems by weathering of rocks.
Sulfates are returned to the ocean, soil, and atmosphere.

There are four major ways sulfur is deposited on land.

As rain falls through the atmosphere, sulfur is dissolved in the form of weak sulfurous acid.
Sulfur is released into the soil by the weathering of sulfur-containing rocks.
These rocks come from the ocean and are moved to land.
Upon the death and decomposition of organisms, the sulfur can be released into the atmosphere as hydrogen sulfide (H2S) gas.

There are sulfur deposits near the mouth of the sulfur vent in Lassen Volcanic National Park.

Sulfur enters the ocean from a variety of sources.

Some organisms use sulfur as a biological energy source.
Sulfates are supported in the form of sulfur.

The balance of the global sulfur cycle has been altered by human activities.

Hydrogen sulfide gas is released into the atmosphere when large quantities of fossil fuels are burned.
Acid rain damages the natural environment by lowering the pH of lakes, which kills many of the resident fauna, and it also affects the man-made environment through the chemical degradation of buildings.
The Lincoln Memorial in Washington, DC, has been damaged by acid rain over the years.

There is a link to learn more about global climate change.

Modeling of energy is best done underground.

Ecological pyramids of energy are one of the ways in which models of ecosystems can be used to understand how environmental changes affect the structure and dynamics of the system.

Simulation models work best with aholistic food environment.

Water, carbon, and webs are important.

Pollution, oil spills, and other human activities may cause Organisms to acquire energy in a variety of global climate change.

The health of Earth is dependent on how the energy flows from the bottom to the top of the food web and how to protect it from irreversible damage.

A re-created environment in a laboratory environment is considered to be a state.

Organisms can make their own food.

A food chain's position is known as its ________.

The mussels live at the NW Eifuku volcano.

The cycle of movement of minerals through organisms is called a _____ cycle.

Carbon is present in the atmosphere.

The average time a molecule spends in its body is called bioentropy.

How would the loss of fungi in a forest be described?

There are three types of pyramids.