UCSF Quiz Chap. 7

sulfur

-.07% earth's crust (most bound in rock minerals) -rock weathering and volcanic activity release sulfur used by organisms -flux of sulfur is high but res. time is short so pool is small

Terrestrial carbon

-560 pg. of carbon is stored in biomass on land--> of that, 90% of it is in plants -without human activity, Earth's total biomass pool is constant -soils of terrestrial ecosystems contain lots of organic carbon (plant waste,dead organisms add carbon to soil) -some of this carbon is in organic compounds consumed by decomposers -other compounds are resistant to decay and reside in soils for many years -NPP and biomass is high in warm/moist regions and low in cold/dry conditions

Nitrogen Cycle

-78% molecules in earth's atmosphere are N2 but only small amounts of N found in Earth's crust, of that 78% that makes up atmosphere, 99% forms N2 (and NH3 and N2O) -plants convert oiorganic forms on N into amino acids/nucleic acids---> animals eat plants/organisms to obtain these compounds---> when animals decay, N is regenerated -humans double rate of nitrogen exchange

phosphorus cycle has influence in NPP in oceans. how?

-NPP in most oceans limited by availability of phosphate -because light only reaches 50-100 m into ocean, photosynthesis occurs in surface waters -BUT phosphorus in surface waters constantly being lost as organic sediment sinks to bottom of ocean -rivers are only new phosphate source to oceans, so where they flow into oceans there's big concentration of phosphorus (NPP bigger along coasts)

human impact on nitrogen cycle

-agricultural ecosystems limited by availability of N in soil -as crops grow, they take ammonium/nitrate/nitrite from soil and covert it into compounds so only a little N left (as amount of N in field decreases, it causes increase in limits on primary production) -availability of nitrogen is limited by rate of fixation, so farmers increase rate by harvesting legumes (contain N-fixing bacteria)

Source of water contributing to rainfall depends on location (explain runoff)

-all rain that falls on oceans comes from water evaporated from ocean's surface, while on land, some of rain comes from water evaporated from terrestrial ecosystems -rainwater that falls on land may flow across surface as RUNOFF (eventually enter lakes)--> gravity pulls lake water to ocean

sequence of events in nitrogen cycle

-animals obtain nitrogen by eating plants/other animals -when decomposers break down wastes, NH3 released into soil -nitrate and nitrite = soluble in water so easily removed from soil and transported into streams

sulfur cycle

-can exist in atmosphere as a gas, but usually found as SO2(4-) (sulfate), SO3(2-) (sulfite), and H2S (involved in volcanic activity) in earth's crust -some bacteria use H2S for chemosynthesis (original version of photosynthesis) -SO2 can be found in the atmospheric portion of sulfur (comes from volcanoes and burning of fossil fuels), when we increase SO2 it contributes to acid rain -it can become SO3 and H2O, which combines to make H2SO4 (sulfuric acid)--> acid rain

Carbon Cycle

-carbon makes up only .032% total mass of lithosphere and atmosphere -majority of carbon found in sedimentary rock, remaining .0005% carbon cycles through biosphere quickly -humans modify carbon cycle by using high energy carbon from ecosystems, using land, and burning fossil fuels

rock cycle

-elements within earth's crust slowly converted from 1 type of rock to another -3 types of rock: igneous, sedimentary, and metamorphic -processes that change rocks include melting and solidification, weathering, and erosion and deposition of sediments -organisms play role in weathering of rocks and formation of sediments

seasons affect cycles

-ex: deciduous trees in forest lose leaves in autumn and are dominant in winter (fallen leaves bring 200 g carbon, 5 g nitrogen, 3 g phosphorus to forest floor) -in winter, leaves decompose, slowing releasing N and P they contain to pool of nutrients in soil -all plants dormant in winter, so unable to absorb these nutrients -by spring, pool of N and P in soil much larger than summer -in lakes, nutrients like N and P constantly being lost from surface water as sediment settles to bottom

human impact on phosphorus cycle

-fertilizers with phosphate increase production of crops -sources of these fertilizers are guano deposits and sedimentary rocks many yrs. old -use of fertilizers and phosphate-rich detergents increased amount of phosphate flowing in streams -when algae growth limited by availability of phosphate, produces eutrophication--> these additions increase algae growth and reduce diversity in ecosystems

human impact on sulfur cycle

-mining activities and burning of fossil fuels cause humans to release twice the amount (150 Tg) released by natural weathering of rock -this atmospheric sulfur contributes to acid rain

phosphorus cycle

-most phosphorous in form PO4(-3), or phosphate -it accounts for .13% of crust -phosphate is found in DNA, RNA, membrane lipids, ATP -follows along the rock cycle -don't need to "fix" in order to use because organisms can use PO4(-3) -phosphate is found in fertilizer, it is a limiting nutrient in systems

Aquatic/Marine carbon

-oceans/lakes contain pool of carbon, much is in form of CO2 (carbon dioxide) -biomass in ocean contributes more NPP than biomass in terrestrial ecosystems. Why? (2 reasons) 1. biomass of plants found in nonphotosynthetic structures like roots and wood 2. phytoplankton grow quickly but constantly eaten by marine herbivores so although NPP of phytoplankton is high, total biomass is low---> res. time for carbon in pool of phytoplankton shorter than time in terrestrial plants

Phosphorus

-phosphorus abundant in crust but not in atmosphere -organisms require phosphorus in form of PO4 (phosphate) to make organic molecules -supply of phosphorus available to organisms is limited by rate of weathering of sedimentary rocks -plants can obtain phosphate dissolved in soil or water, others obtain through food web -phosphorus important limiting factor on ocean NPP -humans mine phosphorus to use as fertilizer so they can increase availability in atmosphere -accounts for .13% crust

assimilation

-plants and animals incorporate the NO3- and ammonia formed through nitrogen fixation and nitrification -Plants take up these forms of nitrogen through their roots & incorporate them into plant proteins and nucleic acids. -Animals are then able to utilize nitrogen from the plant tissues.

factors that affect variation in rates of exchange of carbon between ocean and atmosphere

-temp and NPP -solubility of CO2 in water decreases as temp increases -all photosynthesis in ocean = near surface

human impact on carbon cycle

-we replace natural ecosystems with farmland/cities/suburbs, use of land has diminished carbon -burning of fossil fuels has large effect on carbon cycle -due to our activities, concentration of CO2 in air is rising 1% each year and causing climate change

disturbance and succession

-when ecosystems disturbed, pools and fluxes are altered and initiate processes of succession that restore cycles -did case study on herbicides applied to watersheds and found that once herbicides removed, growth increased rapidly because watershed allowed to undergo succession -within 2 years, rate on nitrate in stream water same as before disturbance

what is the rate of organic matter to replace itself per year?

.01 pg/yr (much slower than rate of conversion into organic matter)

5 steps of nitrogen cycle

1. Nitrogen fixation (N2 to NH3/ NH4+ or NO3-) 2. Nitrification (NH3 to NO3-) 3. Assimilation (Incorporation of NH3 and NO3- into biological tissues) 4. Ammonification (organic nitrogen compounds to NH3) 5. Denitrification (NO3- to N2)

sequence of events in phosphorus cycle

1. as organic matter (DNA, RNA, phospholipids in membranes) decomposes in soil, inorganic phosphate is released and dissolves in soil water 2. plants absorb this phosphate and use to make organic phosphate compounds (all other terrestrial organisms obtain organic phosphorus from things they eat) ---> waste/dead organisms replenish organic phosphate in soil, completing terrestrial portion on cycle

sulfur cycle

1. as rocks weather, sulfur in them dissolves in water and forms sulfate ions (SO4(2-))--> these ions easily taken up by organisms -some chemosynthetic organisms use energy released when H2S converted to S -avg. res time in atmosphere only a few days because forms of gaseous sulfur quickly converted to sulfate, which dissolves in water to form sulfuric acid (acid rain) -sulfate also important part of dust that falls back to earth's surface 2. seawater, decomposition, volcanic eruptions add sulfur to atmosphere (largest input comes from seawater droplets from ocean surface) -decay of organic matter releases H2S into air -volcanic eruptions release S into air as crystals of SO2 (sulfur dioxide) -crystals of S)2 given off by volcanoes reflect solar radiation --> have cooling effect on atmosphere

1. igneous rocks 2. sedimentary rocks 3. metamorphic rocks

1. form as magma solidifies 2. form when sediments, such as sand/silt/remains of dead organisms, become "glued together" under pressure 3. form when great heat and pressure transform physical and chemical properties of sedimentary and igneous rocks

the rock cycle process, sequence of events

1. when temp. and pressures in crust are sufficient, all types of rock melt and form magma--> as magma cools, it solidifies to form igneous rock ---> if magma solidifies beneath earth's surface, it forms intrusive igneous rock (like granite) because cools very slowly and causes it to have a rough texture ---> if magma is ejected onto earth's surface, forms extrusive igneous rock (ex: basalt), it cools quickly so it has small crystals 2. variety of factors cause rocks earth's surface to weather (break into smaller pieces) -the rock particles left by weathering make up major part of soil 3. in process of erosion, weathered rock particles/soil are carries away by gravity, wind, water, etc and deposited as sediment like mouth of river -shells, and undecomposed organic matter also make up sediment -minerals that percolate through sediment glue particles together and form rock, as layers of sediment are created their weight puts pressure on layers below and accelerates rock formation 4. high temps. and pressures associated with tectonic processes alter properties of sedimentary and igneous rocks, producing metamorphic rocks -conditions under which metamorphic rock forms determines its chem. structure---> this influences the soils that form when it weathers (ex: in presence of water and metal elements, igneous rocked transformed into metamorphic rock called serpentine)

Streams and rivers carry a lot of phosphorus to ocean but only ____% is available to aquatic animals as dissolved phosphate.

10% -remainder is bound to soil particles/sediments that sink to bottom ----> these particles become sedimentary rocks -algae able to take up dissolved inorganic phosphate and covert to organic, others obtain it through food web

elements that make up human body and their percentages

65% oxygen, 18.5% carbon, 9.5% hydrogen, 3.3% nitrogen and others

flux of carbon into ocean

92 pg a year, of that, 51 pg is turned into biomass -most carbon is in ocean, ocean is 38000 pg -areas near coast fix more carbon that areas in center of continent

ammonification

Assimilation produces large quantities of organic nitrogen, Ammonification is the conversion of organic nitrogen into ammonia -The ammonia produced by this process is excreted into the environment and is then available for either nitrification or assimilation

nitrogen fixation

ONLY bacteria convert N2 (nitrogen gas) to NH3 (ammonia) -basically convert gas to something substantial -organisms then take ammonia to make amino acids, RNA, and DNA -rate of nitrogen fixation is 10^11 kg/year or 100 tg -NH3 can react with water to make ammonium and hydroxide -ammonium (NH4+) can then be made into nitrate (NO3-) and nitrite (NO2-) in nitrification

nitrification

ammonium (NH4+) can then be made into nitrate (NO3-) and nitrite (NO2-)

net primary production (NPP)

amount of organic carbon available to all nonphotosynthetic organisms in ecosystem

net ecosystem production (NEP)

amount of organic carbon left each year after subtracting respiration of nonphotosynthetic organisms from NPP, it is the net flux of carbon into an ecosystem -if total carbon in biomass of organisms is constant, then NEP = 0 -if total carbon increases (ex: succession), NEP = positive -if total carbon decreases (ex: ecosyetem burned by humans), NEP = negative

residence time

avg. time an atom of an element/molecule of a compound spends in a pool -res. time of water molecule evaporating from ocean is 9.5 days, if water falls as rain and is captured as runoff = 14 days, and groundwater = thousands of years

cycling time

avg. time it takes an element or molecule to make its way through an entire biogeochemical cycle

nitrification

bacteria in soil covert NH4+ to nitrite (NO2-) and nitrate (NO3-) -plants then take up ammonium, nitrate and nitrite through roots and use it to make N-containing organic molecules

majority of phosphorus in crust occurs in rocks as...

calcium phosphate (a.k.a apatite) -apatite common in sedimentary rocks that form in marine environments---> as these rocks weather, calcium phosphate in them dissolves and releases phosphate ions (HPO4(2-)) into soil -this slow weathering process is source of all phosphorus that cycles through biosphere

much of CO2 dissolved in ocean reacts to form...

carbonate (CO3(2-)) and bicarbonate (HCO3-) ions -dissolves CO2, carbonate and bicarbonate make up 99% ocean carbon -carbonate and bicarbonate combine with calcium to form calcium carbonate (primary structural component in shells of marine animals) -when marine animals die, calcium carbonate in shells dissolve and it is converted back to CO2, remains sink to bottom of ocean and form sedimentary rock ---> over many years, may be transformed into oils and natural gasses -total pool of carbon in oceans must be increasing (there is 2 pg surplus returned to air as compared to what is absorbed)

nitrogen in soil and water is returned to atmosphere via..

denitrification -specialized bacteria convert NO3- to nitrogen gas -total nitrogen in Earth's organisms, soils, and waters is determined by balance between fixation and denitrification

Hydrologic cycle

describes distribution and flux of water through earth's biogeochemical system -most of earth's water is in oceans, of the remaining amount, 99% of it occurs in saturated rocks out of reach of plant roots -total annual precipitation = total annual evaporation 1. precipitation transfers water vapor in atmosphere to liquid water in hydrosphere 2. once on ground, liquid water has 3 options: evaporate, flow into streams and eventually to ocean, or percolate through soil to become ground water -water evaporates from soil, bodies of water, and leaves of plants

transpiration

evaporation form leaves -this is a major component of evaporation in terrestrial ecosystems because of large surface area of leaf

gravity causes some water to percolate through soil and into the rock below as...

groundwater

what happens when carbon "fixes" in water?

it reacts with H2O to create carbonic acid, which can be broken down and mixed with calcium to create calcium carbonate (shells)

aquifer

layer of soil or rock saturated with groundwater -about .1-5% total rainfall reaches aquifer -groundwater moves through rock slowly and eventually is delivered to ocean

humans use legumes to regenerate soil because...?

legumes have bacteria that don't take out as much nitrogen in soil -humans are pulling more nitrogen out of atmosphere than what is being put in due to use of fertilizer and fossil fuels

nitrogen is a _______ nutrient. why?

limiting! -reason is because plants cannot absorb nitrogen is atmospheric form (N2) -it must be broken down by lightning and microorganisms first into soluble forms for plants to be able to take it in

macronutrients. vs. micronutrients

macro: elements organisms require in large amounts (ex: carbon, nitrogen, oxygen, hydrogen)---> play role in energy transformation in photosynthesis and C.R micro: require in smaller amounts (ex: boron)---> play role in catalytic function of enzymes

biosphere

made of all organisms and nonliving components of environment with which they interact

because ammonium and nitrate dissolve in water, runoff carries them into lakes----> high rates of fixation lead to..

more ammonium and nitrate in lakes, higher nitrogen concentration creates a rapid growth of algae -this growth leads to eutrophication: organic matter from algae encourages high rates of respiration by decomposing organisms -N also added to biosphere when humans burn fossil fuels---> causes acid rain -increase in human activities means an increase in nitrogen fixation

denitrification

nitrate and nitrite are converted back to nitrogen gas (N2)

nitrogen enters biosphere via process called...

nitrogen fixation -in fixation, N2 converted to NH3 -most fixation carried out by nitrogen-fixing bacteria (which convert N2 to NH3 and then into N-containing organic molecules) -ammonia dissolves in water to form ammonium (NH4+)---> bacteria in soil covert NH4+ to nitrite (NO2-) and nitrate (NO3-) in process called NITRIFICATION

what is the majority of nitrogen on earth found as?

nitrogen gas (N2), some is present as NH3 and N2O -nitrogen makes up only .003% earth's crust

haber-bosch process

nonbiological process of nitrogen fixation -used for producing chemical fertilizers

what do we need nitrogen for?

organic molecules: nucleic acids and proteins

flux of carbon between atmosphere and terrestrial/aquatic ecosystems is tightly coupled to...

photosynthesis and cellular respiration -photosynthetic organisms use light to add H+ ions and electrons to CO2, producing carbs and other organic molecules -in cellular respiration, hydrogen is removed from organic compounds, oxygen is added, and organic carbon is converted back to CO2

pools vs. fluxes

pools: parts of ecosystem in which matter may reside, such as atmosphere or soil fluxes: rate at which matter moves from 1 pool to another

coastal areas are more ____ than center of continent.

productive -they receive more nutrients because of runoff from land (ex: Denmark waters become anoxic due to excess nitrogen)

elements with short cycling times vs. long

short: elements abundant in atmosphere (like nitrogen, oxygen, and carbon) long: phosphorous, calcium, iron, etc have chem. forms tied up in soils/rocks so flow through biosphere slowly

carbon fixation

taking carbon from the atmosphere and changing it to a solid

capital of a pool

total amount (mass) of element or molecule that it contains -pool sizes measured in tetragrams -fluxes into pool = positive -fluxes out of pool = negative -equilibrium: net flux = 0 and capital of pool is constant

gross primary production (GPP)

total amount CO2 that photosynthetic organisms covert to organic carbon each year -these producers use half GPP in cellular respiration to carry out their own life functions, remaining half is net primary production