LS 1 - Ch 25

volcanism

A key physical process that adds/removes CO2 from the atmosphere is volcanism: Volcanoes and mid-ocean ridges release an estimated 0.1 billion metric tons of carbon (as CO2) into the atmosphere each year.

food web

A map of the interactions that connect consumer and producer organisms within the carbon cycle; the movement of carbon through an ecosystem.

What accounts for the short term carbon cycle?

1. *Photosynthesis* 2. *Respiration* are complementary metabolic processes that drive the short-term carbon cycling through biosphere.

oxygen level did not increase to the level that humans could survive until ___ mya and coincided with the appearance of ___

580 mya; animals

photosynthesis

6CO2 + 6H2O → C6H12O6 + 6O2 - uses sunlight to reduce CO2 --> C6H12O6 - oxidizes H2O --> O2 - This annual photosynthetic removal of CO2 equals about 25% of the total CO2 in the atmosphere.

Carbon isotopes show that ____

much of the CO2 added to air over the past half century comes from burning fossil fuels.

- When oxygen production by photosynthesis and oxygen consumption by respiration are in balance, oxygen levels _____ change/inc/dec?

oxygen levels do not change.

Records of atmospheric composition over 400,000 years show ____ in CO2 content.

periodic shifts

Variations in atmospheric CO2 over hundreds of millions of years reflect _____ and _____

plate tectonics and evolution.

plate tectonics provides geology's best explanation for the formation of mountains and ocean basins____ and _____, and it plays an important role in the___ -term carbon cycle.

plate tectonics provides geology's best explanation for the formation of mountains and ocean basins, and it plays an important role in the long-term carbon cycle. long-term carbon cycle

How is oxygen related to carbon cycle? When life began, the atmosphere and oceans contained little or no oxygen gas. How did our present environment come to be?

*Photosynthesis and respiration* - cycle carbon and oxygen (and water)

Why does food web describe the biological world better than food chain ?

- Food webs provides a better sense of the complexity of biological interactions within the carbon cycle by addressing how heterotrophs within a community can consume or be consumed by a number of other species. - Food webs define the interactions among organisms in many habitats. - main point : food webs track the passage of carbon atoms through the biological carbon cycle.

How are human activities adding carbon to the atmosphere? In what form is the carbon being added?

- add almost 9 billion metric tons of carbon to the atmosphere each year - form: CO2. - how? oxidize ancient organic matter to CO2 on a grand scale through >> power plants >> airplanes >> ships >> automobiles >> conversion of forests (cleaning/burning) to agriculture or pastureland.

How does cursory examination support the seasonality of photosynthesis?

- cursory examination of the Earth shows that *land is distributed asymmetrically* - more land—> more plants—in the Northern Hemisphere than in the Southern Hemisphere. ==> 1. global atmospheric CO2 declines through the northern summer, when the ratio of photosynthesis to respiration is highest 2. increases through fall and winter, when the ratio is reversed.

biggest C resorvoir

- within sediments and sedimentary rocks. ----Calcium carbonate minerals (CaCO3) > form limestone ---- organic: Coal, petroleum, and natural gas

Where did much of the "missing carbon" go?

--> stored as inorganic carbon in the form of CO2, bicarbonate (HCO3-), and carbonate (CO32-) ions dissolved in the oceans FIG. 25.5 Carbon dioxide sources and sinks http://www.macmillanhighered.com/BrainHoney/Resource/6716/digital_first_content/trunk/test/morris2e/asset/img_ch25/morris2e_ch25_fig_25_05.html

The temperature of cold glacial and warm interglacial periods correlate with minimum and maximum atmospheric CO2 levels, respectively. How can we explain this correlation?

1. CO2 is a greenhouse gas. It allows incoming solar radiation to reach Earth's surface but traps heat that is re-emitted from land and sea. Higher concentrations of CO2 result in warmer temperatures. 2. the periodic growth and decay of continental ice sheets.

What causes atmospheric CO2 to vary through the year and over a timescale of decades? --> what processes introduce CO2 into the atmosphere and what processes remove it?

1. Carbon dioxide is *added* to the atmosphere by (1) geological inputs, mainly from volcanoes and mid-ocean ridges (2) biological inputs (esp respiration) (3) human activities (deforestation, burning of fossil fuels etc.) 2. Processes that *remove* CO2 from the atmosphere include (1) geologic removal (esp. chemical weathering : CO2 in rainwater reacts with exposed rocks) (2) biological removal: (mainly thru photosynthesis)

What does the Keeling curve show?

1. The Keeling curve provides a record of atmospheric CO2 concentrations over half a century, measured from an observatory at Mauna Loa, Hawaii. - result: a steady increase in CO2 concetration over 50 years 2. short term carbon cycle (in a year) - result: CO2 concentrations regularly cycle up and down throughout a year. ------- the observation could be local .

Atmospheric CO2 and, hence, climate, are determined in large part by geologic processes:___ (3)

1. changes in the rate of organic carbon burial in sediments 2. continental weathering of rocks uplifted into mountains 3. volcanic gas release.

12C vs. 13C vs. 14C

12C (with six neutrons, about 99% of all carbon atoms) 13C (with seven neutrons, most of the remaining 1%) rare 14C (with eight neutrons, about one part per trillion of atmospheric carbon).

carnivores

A monophyletic group of animals, including cats, dogs, seals and their relatives, that consume other animals.

causation

A relationship in which one event leads to another.

reservoir

A supply or source of a substance. Reservoirs of carbon, for example, include organisms, the atmosphere, soil, the oceans, and sedimentary rocks.

Quick Check 2 If plate tectonic processes form a chain of high mountains, would you expect atmospheric CO2 to increase or decrease?

All else being equal, increasing the elevation of mountains should increase rates of chemical weathering and erosion. As chemical weathering of continental rocks consumes CO2, atmospheric CO2 levels should decline.

decomposer

An organism that breaks down dead tissues, feeding on the dead cells or bodies of other organisms.

consumer

An organism that obtains the carbon it needs for growth and reproduction from the foods it eats and gains energy by respiring food molecules; heterotrophic organisms of all kinds that directly consume primary producers or consume those that do.

primary producer

An organism that takes up inorganic carbon, nitrogen, phosphorus, and other compounds from the environment and converts them into organic compounds that will provide food for other organisms in the local environment. - also : photosynthetic organisms autotrophs ("self feeders") --they synthesize the organic molecules needed for growth and reproduction from CO2.

What's the relationship between geological processes and biological processes in terms of carbon cycle?

As we will see, geologic processes play key roles in the carbon cycle on timescales of centuries and longer. Only biology, however, can account for the annual rhythm of the Keeling curve.

biodiversity.

Biological diversity; the aggregate number of species, or, more broadly, also the diversity of genetic sequences, cell types, metabolism, life history, phylogenetic groups, communities, and ecosystems

How do humans accelerate oxidation of sedimentary organic carbon?

By burning fossil fuels, humans accelerate this process dramatically, increasing a hundredfold the rate at which sedimentary organic carbon is oxidized.

Which chem reaction summarize 2 linked processes of chemical weathering and mineral precipitation? What stands in for rock-forming minerals as a whole?

CaSiO3 + CO2 → CaCO3 + SiO2 CaSiO3

How does the anatomy of fossil leaves substitute for direct measurements of ancient CO2 levels?

Experiments show that *stomata*, the small pores on leaf surfaces , *decrease in density* as atmospheric CO2 levels increase

The biodiversity of photosynthetic organisms found today reflect both the evolutionary variations in biochem of photosynthesis aand structural/ physiological adaptations equally. T/F

False. - The immense diversity of photosynthetic organisms found today does not reflect evolutionary variations in the biochemistry of photosynthesis (although some of that occurs; see Chapter 29) so much as it does *structural and physiological adaptations*. - These adaptations allow the effective gathering of light, nutrients, and—critical to life on land—water, in widely varying local environments. - - *Natural selection*, acting on local populations, links the diversity of photosynthetic organisms to the carbon cycle.

What observation did Suess make from comparing C isotopes?

He observed that the *proportion of 13C in atmospheric CO2 has declined as the total amount of CO2 has increased*. Why? This subtle change in isotopic composition has occurred because the *CO2 being added to the atmosphere has less 13C than the CO2 already in the air*.

primary consumers

Herbivores, which consume primary (plant or algae) producers. Sometimes called grazers.

How does photosynthesis not deplete the carbon in the atmosphere?

Photosynthesis and aerobic respiration are complementary metabolic pathways: Each uses the products of the other and generates a new supply of substrates for its complement. The result is a cycle

the carbon contained in the total mass of organisms living on land Vs carbon stored as CO2 in the atmosphere

If we add up all the carbon contained in the total mass of organisms living on land, that amount of carbon is just a bit smaller than the amount of carbon stored as CO2 in the atmosphere.

Why must the processes that cause a net conversion of organic matter to CO2, for example by burning, be adding CO2 to the atmosphere?

In photosynthesis, CO2 containing the lighter isotope 12C is incorporated into biomolecules preferentially over CO2 containing 13C, and for this reason organic matter generated by photosynthesis (and the organic matter of organisms that eat photosynthetic organisms) differs in its proportions of 13C and 12C from CO2 from volcanic gases and inorganic carbon dissolved in the oceans. - Volcanic and dissolved marine carbon do not have the right ratio of 13C to 12C to explain the isotopic change observed in the atmosphere over time. - In contrast, organic matter in living organisms has just the right ratio of 13C to 12C to account for Suess's measurements.

How is the hypothesis that human activities cycle carbon in amounts high enough to affect the chemical composition of the atmosphere supported?

Modern organic matter contains too much 14C to account for the observed pattern - but ancient organic matter—the coal, petroleum, and natural gas burned as fossil fuels—is isotopically just right.

Where/how is carbon mostly stored in the water?

Much more resides as inorganic carbon dissolved in the water— *most of it in the deep oceans as CO2 and bicarbonate and carbonate ions.* - amt of carbon in the ocean is really little

secondary consumers

Predators or scavengers that feed on primary consumers.

Which component of the food chain is the first biological reservoir for carbon once it has been taken out of the physical environment?

Primary producers

____ and ___ are key in long-term carbon cycling.

Reservoirs and fluxes

Biological diversity reflects the many ways that organisms participate in the carbon cycle. T/F

T

The chemistry of ancient soils is also thought to reflect atmospheric history. T/F

T

The historical record of the past 400,000 years shows that climate can and does change without any input from humans. T/F

T: atmospheric CO2 oscillates in parallel with glacial expansion and retreat could be explained by suggest interactions involving the ocean and its large reservoir of inorganic carbon. example: - it has been hypothesized that during glacial advances, the circulation of carbon-rich deep-ocean waters back to the sea surface slows, causing more inorganic carbon to accumulate in the deep sea. With glacial retreat, the oceans circulate more vigorously, returning CO2 to the surface and then to the atmosphere.

What does the sensitivity of diff reservoirs to change depend on?

The sensitivity of different reservoirs to change depends on *the relative sizes of the reservoir and of the amount of movement of material into and out of it*. - When fluxes are large relative to the size of the reservoir, reservoir size can change rapidly

community

The set of all populations found in a given place.

food chain

The transfer of carbon from one organism to another

correlation .

The co-occurrence of two events or processes; correlation does not imply causation

Quick Check 1 How does the graph in Fig. 25.3 suggest that human activities have influenced CO2 levels in the atmosphere? What might be a plausible alternative hypothesis?

The coincidence in timing between the Industrial Revolution and the observed increase in CO2 levels—following a millennium of little change—suggests that human activities played a role in recent changes in atmospheric composition. Alternative hypotheses would focus on other processes that add CO2 to the atmosphere. Perhaps, for example, increased volcanic activity added more CO2 to the atmosphere, or perhaps warming induced by changes in solar radiation caused thawing of permafrost, facilitating increased respiration of soil organic matter at high latitudes. These hypotheses can be tested against the historical record of volcanic activity and measurements of solar radiation over the past century.

plate tectonics

The dynamic movement of Earth's crust, the outer layer of Earth.

Life can drive environmental change through time. For example, the large drop in atmospheric CO2 suggested for the mid-Paleozoic Era, 400-350 million years ago (see Fig. 25.11), is thought to reflect the evolution of a new player in the carbon cycle: woody plants. How does the evolution of trees increase the size of C reservoir?

The evolution of trees increased the size of the carbon reservoir on land and ushered in an important new mechanism for removing carbon from the air and ultimately to sedimentary rocks. -->That mechanism was the *burial of plant material on land, forming peat and, eventually, coal*.

carbon cycle

The intricately linked network of biological and physical processes that shuttles carbon among rocks, soil, oceans, air, and organisms.

biomineralization

The precipitation of minerals by organisms, as in the formation of skeletons. sig:__ provides yet another link between Earth and life

flux

The rate at which a substance, for example carbon, flows from one reservoir to another.

Why is the ratio of 18O:16O in glacial ice cores a good indicator of past temperature?

The ratio decreases as temperature decreases.

What does the regular oscillation of CO2 reflect?

The seasonality of photosynthesis in the Northern Hemisphere. - higher rates in the summer and lower rates in the winter.

Photosynthesis is seasonal where as respiration remains more or less constant through the year. T/F

True

The carbon cycle weaves together ___ and____through Earth history.

biological evolution and environmental change

To grow, all organisms require __ and ___

carbon and energy

What geologic processes remove carbon from the atmosphere?

chemical weathering: About 0.43 billion metric tons of CO2 are removed from the atmosphere by chemical reactions between air and exposed rocks. - CO2 in the air + rainwater --> carbonic acid (H2CO3). - This acid slowly reacts with rock-forming minerals --> (among other substances) calcium and bicarbonate (HCO3-) ions that are transported by rivers to the oceans. - Within the oceans, calcium + bicarbonate ions r--> calcium carbonate (CaCO3) minerals --> precipitate out of seawater and accumulate on the ocean floor --> forming limestone. In essence, carbon moves from the atmosphere to the sediments, where it can be stored for millions of years.

Food webs trace the cycling of carbon through ___ and ____

communities and ecosystems.

Before that, however, higher levels of CO2—perhaps four to six times the 1958 level—characterized the Mesozoic Era (252 to 66 million years ago), a generally warm interval commonly known as the age of dinosaurs.

http://www.macmillanhighered.com/BrainHoney/Resource/6716/digital_first_content/trunk/test/morris2e/asset/img_ch25/morris2e_ch25_fig_25_11.html

When some of the organic carbon generated by photosynthesis is buried in sediments --> avoiding being returned to the environment through respiration --> oxygen level inc/ dec/ remains constand??

increase - some of the O2 also generated by primary producers can accumulate in the atmosphere and oceans. - In other words, because sedimentary organic matter burial can break the tight coupling b/n photo and respi. --> it can facilitate an increase in O2 through time.

. Subduction

removes carbon from Earth's surface, but this carbon will be recycled to the surface as CO2 emitted from volcanoes and mid-ocean ridges. Fig. 25.8 shows the physical processes at work in Earth's long-term carbon cycle. The crust that descends into subduction zones carries with it sediments, including carbonate minerals and organic matter

carnivores are a part of ___ consumers

secondary consumers

The "excess" organic carbon produced by photosynthesis is deposited in ____ as they accumulate on land or the seafloor, sustaining a small but constant leak of carbon from the short-term biological components of the carbon cycle to long-term geologic reservoirs.

sediments

New crust forms at_____. Old crust is destroyed in_____

spreading centers, the places where molten rock rises upward from the underlying mantle; ; subduction zones, where one slab of crust slides beneath another, returning material to the mantle. q

Scientists continue to debate why atmospheric CO2 oscillates in parallel with glacial expansion and retreat, but, increasingly, proposed mechanisms suggest interactions involving＿＿＿ and ＿＿＿

the ocean and its large reservoir of inorganic carbon.