Unit 3: Environmental Science

Peter Vitousek

1997; led Standford Scientists to study nitrogen cycle

Issues with nitrogen cycle by man

2x the rate of N entering terrestrial systems, increased concentraion of greenhouse gases, fertilizer flush, acidified waters and soils, increased N in rivers and oceans, less biodiversity (more growth of N plants)

Pools/Reservoirs

As nutrients move around they do tend to stop in various areas or organisms for periods of time called _________.

Ocean

A large amount of carbon is exchanged between the atmosphere and the ___________.

Limiting factor

A physical, chemical, or biological characteristic of the environment that restrains population or organism growth: as a _________ phosphorus is second only to nitrogen

Wastes

All consumers will also add phosphorus back to the soil through excretion of ________, decomposers will also break down organisms that were phosphorus rich and put that phosphorus back into the soil (sink).

Nutrient

An element or compound that organisms consume and require for survival

Detoxified

Animal waste especially urine is also rich in nitrogen; these contain the __________ wastes of protein metabolism.

Haber-Bosch process

Artificial nitrogen fixation

Sediment

As organisms die and decompose they are often times covered in ________ as this happens over long periods of time the amount of __________ that is covering the decaying organism grows and adds more pressure on this dead organism.

Proteins

As plants shed leaves, needles, flowers, fruits, and cones and animals get rid of fur, feathers, skin, exoskeleton, pupal cases and silk all are getting rid of _______ which are made up of nitrogen. Once these are broken down and decomposed by fungi and bacteria the nitrogen reenters the cycle in the soil in the form of ammonia or ammonium

Combustion

At the present time things like natural wildfires and human created ________ of organic fuels release large quantities of CO2 into the atmosphere

Volcanic

Carbon in the ocean floor is often released through ____________ activity and it is estimated that every carbon atom on earth has made that journey about 4 times in the last 4 billion years.

Phosphorus Cycle

Cycle consisting of routes that phosphorus atoms take through the nested networks of environmental systems

Acidic

Due to the large amounts of CO2 that the oceans are taking out of the atmosphere it is actually causing the ocean chemistry to change and become more _______, this in turn has led to ocean coral bleaching and in turn dying as well as some species that are right on the edge of their pH to be threatened with extinction

Nutrient Source

If a reservoir releases more nutrients than they accept they are considered ________.

Nutrient Sink

If the reservoir accepts more nutrients though than it releases it is known as a __________.

Decomposers

In the absence of human disturbance the exchange of carbon between the atmosphere and the earth's surfaces was a steady state as carbon is taken up through photosynthesis eventually ending up in the soil to be broken down and re-released through respiration by ___________.

Fire

In the case of _________ though it does convert nitrogen that was in the once living plants as well as the dead "duff" into a usable form that new plants (seedlings and emerging perennials) can use.

Sequestering

It has been estimated that 20-40% of the carbon we are hoping to eliminate from emissions can be met by ___________ or tying up that carbon within the soils

420,000

It is estimated that the atmospheric CO2 available at the moment is the largest it has been in the last ________ years.

0.6

It's tied up in rocks and actual phosphorus in the soil is only about _________%. Phosphorus in the soil depends on the soils parent material, degree of weathering, and climatic conditions

Macronutrient

Key elements that organisms need in relatively large amounts (Nitrogen, phosphorus, & Carbon are examples)

Aquatic

Leached nitrates can eventually settle in the bottom of ________________ areas.

Fabaceae

Members of the ________ family plants as well as a couple of others actually have nitrogen fixing bacteria that are attached to their roots (nodules). Legumes with their associated bacteria can actually put nitrogen back into the soil in a useful form for other plants (crop rotation principle)

Weathering

Most of the earth's phosphorus is actually contained in rocks and tends to be released only by ___________, which is an extremely slow process. This releases phosphate ions (PO43-) which for the most part will be dissolved in water systems (lakes ocean usually).

Plants

Most organisms, aside from _________, get their nitrogen by eating plants and assimilating the nitrogen from them.

3

Nitrogen is an important component of amino acids, peptides, nucleic acids, and proteins. It makes up about _______% of our body weight

Ammonification

Nitrogen will re-enter the environment in several other ways. When things die their bodies will be decomposed by fungi and bacteria which release ammonia and ammonium ions.

Temperature

Oceans are the second largest carbon reservoir in the carbon cycle; the rate at which the oceans can absorb and release CO2 depend on such things as _______ and the number of marine organisms converting CO2 into carbohydrates and carbonates

Ammonium

Often times plants use nitrogen fixing bacteria found in most soils that have the ability to "fix" nitrogen and turn it from its N2 form into a nitrite form NO2-, this in turn is turned from nitrite into nitrate by another group of bacteria so the NO2:goes to NO3:which can then be taken up by the plants and changed to NH4+ which is _________.

Assimilation

Once the producers obtain fixed nitrogen they can then incorporate it into their tissues this is known as __________

Nitrate

One way that nitrogen in the atmosphere can be broken and used by plants is through the intense energy released when lightning strikes the earth or from combustion due to fires and N2 is changed into ________ which is a form usable by plants this of course will also kill the plant.

Carbon sources

Originating point of carbon that reenters the carbon cycle; cellular respiration and combustion are examples

Atmospheric

Phosphorus has no ___________ form besides the transport of tiny windblown dust and sea-spray.

Limiting

Phosphorus is considered a ____________ factor in many ecosystem especially for plant growth, but also within freshwater ecosystems as well. It is because of this that when we see an artificial influx of phosphorus that the effects are so immediate and dramatic.

Inorganic

Phosphorus is mined out of rocks and sediment for use in __________ fertilizers much of this sediment is coming from exposed ocean sediment that are millennia old

Precipitates

Phosphorus is not very soluble in water, so most ________ out of solution into a solid form and sink to the bottom of whatever aquatic area they landed in.

Main parts to the Carbon Cycle

Photosynthesis, respiration, exchange, sedimentation and burial, extraction, and combustion

Carbon sinks

Places of carbon accumulation, such as in large forests or other areas with a high amount of organic compounds, or ocean sediments

Water

Plants are able to take phosphorus up through their roots, but only if the phosphate has been dissolved in _______.

Air

Plants obtain nitrogen by taking up inorganic nitrogen from the environment. While nitrogen is the most abundant gas in the atmosphere, plants can't do anything with the stable triple bonded N2 molecule that is found in the _____

271

Prior to the mid-18th Century atmospheric carbon concentrations had changed very little for 10,000 years, since then human beings have added about _________ billion tons of carbon into the atmosphere through our various means of combustion

Biomass

Scientists are using _________ data as well as measuring the soils organic carbon at various depths to see how native grasses and forbs are adding carbon back to the soil, as well as determining how much carbon is being held within their above and below ground plant material

Algal

Sewage discharge both treated and untreated also tends to be a high in phosphates, which will run off into waterways, this will promote __________ growth

Soil Cores

Soil data is determined using _______, drying them to remove water weight, then grinding them and sieving out root material as well as conducting chemical analyses on the soil to determine pH, total C, and inorganic C

Diffuses

Some of the carbon that ______ into the ocean is used by the producers of the ocean.

Sugar

The ______________ molecules are eventually broken down during cellular respiration and the carbon is re-released into the atmosphere as CO2 this closes that small portion of the cycle

Atmosphere

The amount of CO2 released from the ocean to the atmosphere is roughly equal to the amount that diffuses from the __________ to the ocean water.

Clay

The amount of carbon a soil can sequester is dependent on the temperature, rainfall amounts, and the _________content in the soil

Low

The amount of phosphorus that is actually available to living organisms tends to be very ________

Residence Time

The amount of time that the nutrient is in the pool or reservoir

Photosynthesis

The carbon cycle begins with ____________ this process is based on CO2 and starts with plants taking CO2 from the atmosphere; incorporates most of this carbon into sugar molecules some of the carbon though is used for making organisms tissues

Carbon Cycle

The circulation and reutilization of carbon atoms, especially via the processes of photosynthesis and respiration

Nutrient Cycle

The comprehensive set of cyclical pathways by which a given nutrient moves through the environment; this is often referred to as biogeochemical cycles as well because they involve biological, geological, and chemical interactions

Cyanobactia

The first step in the nitrogen cycle and is usually done by _____________, certain soil bacteria, and special bacteria that live in root nodules of plants in the legume family (Fabaceae)

Flux

The movement of nutrients among pools (will change over time depending on outside influences)

Bacteria

The nitrogen reenters the atmosphere in a series of steps utilizing several different types of _________. The first group turns NH4 into nitrite (NO2) then other _____________ will convert nitrite into nitrate (NO3) in a two-step processes known as nitrification.

Eutrophication

The process of nutrient enrichment, increased production of organic matter, and subsequent ecosystem degradation leads to an algal bloom

Leaching

These are negatively charged particles of nitrate dissolve readily in water and don't tend to bind as well to the soil as phosphate ions. For this reason they tend be easily transported through the soil by water through _________.

Erosion

This newly formed nitrate can also be carried by ______ after rain events to new areas

Fossil Fuels

This ongoing flux of carbon from ____________ to the atmosphere could have huge effects on the global climate since CO2 is considered a major component to global warming. It has been calculated that a molecule of CO2 released into the atmosphere due to burning _________ will in its lifetime in the atmosphere trap a thousand times more heat than was released when that molecule of CO2 was released.

Our effect on nitrogen cycle

Use of synthetic fertilizers, N fixing crops, burning fossil fuels (doubled the of nitrogen cycled in the environment; increased nitrious oxide acidified aquatic areas; hypoxia zone in Gulf of Mexico has spread)

50-70

With agricultural land such practices as conservation tillage(.24-.4 MTC/ha/y) fertilizer management(0.05-0.15 MTC/ha/y), Rotation with winter cover crops(0.1-0.3 MTC/ha/y) would save carbon from leaving the soil as well as add carbon to a reservoir that we have been depleting carbon from for the last____________ years

Fast

_______ portions of the Carbon Cycle involve portions that are associated with living organisms

Extraction

________ is mostly done by us in the form of removing fossil fuels and is a fairly recent addition to the carbon cycle. While extraction alone doesn't alter the carbon cycle that much, the combustion of those fossil fuels does have an impact.

Slow

________ portions of the Carbon Cycle involve associations with rocks and minerals

Carbon

_________ serves a dual purpose for organisms, it is a major structural component for all of the organic molecules within the organism, and it forms energy holding chemical bonds that many organisms use as energy storage.

Nitrogen

__________ is the most important limiting agent when it comes to constraining plant growth.

Nitrogen Cycle

__________ the circulation and reutilization of nitrogen in both inorganic and organic phases

Primary

___________ consumers with in an ecosystem (herbivores) will get phosphorus from water and plants and they in turn will pass that phosphorus along to secondary and tertiary consumers (sink).

Phosphates

____________ were used in many types of household soaps and detergents from the 1940's to 2010 most laundry detergent companies quit adding it by 1994, dish detergent did the same in 2010.

LEEDS (Lake eutrophication effect dose sensitivity model)

_____________ was designed to predict how large a fish farm a lake could sustain without incurring eutrophication problems. Found that the biggest uncertainty was in the rate of total phosphorus sedimentation; all other internal influxes (re-suspension, diffusion, etc) were dependent on this rate.

Denitrifying

______________ bacteria in these low oxygen areas will break down nitrates into N2 and N2O (nitrous oxide) which are gases that return to the atmosphere. (Completes the Nitrogen Cycle)

De-nitrification

______________ typically occurs in soils that are more waterlogged with low oxygen availability and high amounts of decomposable organic matter (swamps, bogs, and fens)

Sedimentary Rock

_________________ comprises the largest reservoir in the carbon cycle.

Cellular Respiration

_____________________, decomposition, and combustion (burning of things) are considered carbon sources

Nitrogen fixation

a process by which some organisms can convert nitrogen gas molecules directly into ammonia