Ch. 3.2: Biogeochemical Cycles

describe nutrient availability compared to energy availability

energy keeps coming from the sun, but nutrients are limited

what is the first step of nutrient recycling?

get absorbed by plants which get eaten by consumers

what is the second step of nutrient recycling?

consumers excrete nutrients back into the air or soil

what is the third step of nutrient cycling?

decomposers break down dead organisms, returning nutrients into the soil

Biogeochemical cycle

nutrients cycling between biotic and abiotic components of an ecosystem

Reservoir

where the nutrient spends most of the time in the Biogeochemical cycle

What do specific biogeochemical cycles depend on?

type of nutrient and trophic structure of the ecosystem

Global Scale reservoir

easily spread worldwide

Global scale reservoir examples

atmospheric or oceanic

what nutrients do global scale reservoirs include

carbon, oxygen, sulfur, calcium, and nitrogen

Local scale reservoir

don’t spread as easily

Local scale reservoir examples

soil or rock

what nutrients do local scale reservoirs include

phosphorous, potassium, trace elements

characteristics of reservoir 1 (living organisms/detritus)

organic and available

characteristics of reservoir 2 (Fossils- coal, oil, peat)

organic and unavailable

characteristics of reservoir 3 (Atmosphere/ soil/ water)

inorganic and available

characteristics of reservoir 4 (minerals in rock)

inorganic and unavailable

Which element is one of the four elements that make up 96% of the body

carbon

where can carbon be found?

living organisms, oceans, air, soil, mostly in rock

what is the estimated number of total carbon in the biosphere

50,000 Gigatons

how much of carbon is actively circulating

less than 1%

what percent of carbon is in Oceans

80%

what percent of carbon is in fossil fuels

10.6%

what percent of carbon is in soil

3.3%

what percent of carbon is in phytoplankton

2%

what percent of carbon is in plants and animal matter

2.5%

what percent of carbon is in the atmosphere

1.6%

list the four processes involved in the cycling of carbon

biological, geological, biogeochemical, human activity

Biological processes examples

photosynthesis, cellular respiration, consumption, decomposition

simple equation of photosynthesis

CO2→ C6H12O6

simple equation of cellular respiration

C6H12O6→ CO2

Geological processes examples

volcanoes releasing CO2, weathering, erosion, and sedimentation

Biogeochemical processes example

fossilization of organisms

Human activity examples

burning fossil fuels, cutting down and burning trees

where is most of earth’s nitrogen located

the atmosphere

how much of the atmosphere is nitrogen, and in what form is it found?

78% N2

Why is N2 unusable by most organisms?

triple covalent bond is too strong

what are the two ways that nitrogen can enter the atmosphere

atmospheric deposition by lightning, nitrogen fixation

Atmospheric deposition by lightning

ammonium and nitrate are added to the soil by being dissolved in rain or settling as dust

how much of usable nitrogen enters the atmosphere through atmospheric deposition by lightning

5-10%

Nitrogen fixing bacteria

use nitrogenase enzyme, which activates in the absence of oxygen

explain the steps of nitrogen fixation according to the diagram drawn in class. select/type “next card” if you got this question right

next card

bacteria can be ____ or ____

free living; symbiotic

what can nitrifying bacteria use as an energy source?

ammonium

Nitrification

NH4+→NO2→NO3-

what can plants make using nitrate (NO3-)

amino acids, nucleotides

what is the only way for animals to get nitrogen?

consuming other plants or animals

Denitrifying bacteria

use NO3- as an oxygen source during anaerobic conditions, producing nitrogen gas and nitrous oxide, which go back into the atmosphere

how does burning fuel disturb the nitrogen cycle? What is formed as a result?

add Nitric Oxide into the atmosphere by combining N2 and O2, converted into NO2 and nitric acid vapor, forming acid rain

how do humans cause nitrous oxide (N2O) to be added to the atmosphere

anaerobic bacteria feeds on livestock waste and fertilizer

how does N2O affect the atmosphere

warms it and depletes ozone

how do humans excess nitrates added to aquatic ecosystems

agricultural runoff and discharge from sewage

how do humans remove nitrogen from the environment

harvest nitrogen-rich crops, irrigation runoff, burning forests and grasslands for farming

from 1950 to 2000, the annual release of nitrogen from the land into the rest of the environment has ____. This was mostly caused by ______.

quadrupled; fertilizer

is the phosphorous cycle local or global?

local

plants can be as high as ___% phosphorous 

2

where do plants get phosphorous from

soil or water

why is Phosphate the limiting factor in an ecosystem?

organisms are sensitive to levels

where can phosphorous be found in an organism

DNA, RNA, ATP, bone, shells, and teeth

where is phosphorous mostly found

rock, soil, sediment

what forms can phosphorous be found in

orthophosphate and inorganic phosphate

how is phosphorous released from rock

erosion wears away at rock and washes it into streams where it is dissolved

what happens when humans add phosphorous to waterways as fertilizers

cause algal blooms and possibly dead zones

how do plants and plankton use phosphate

put it into organic molecules

how do plants use phosphorous

they pick it up with help from fungi associated with plant roots

how do phytoplankton use phosphorous

can use dissolved marine phosphate

where can sulfur be found in

proteins, vitamins, and hormones

how is most of sulfur found as? where is it stored?

sulfate; rock

what are sulfates converted by? what are they converted into?

plants, fungi, prokaryotes; organic sulfhydryl groups

how is hydrogen sulfide added to the atmosphere in swamps and mudflats

anaerobic prokaryotes

how is hydrogen sulfide and sulfur dioxide added to the atmosphere

volcanoes

what do some marine algae produce? what does it help with?

dimethyl sulfide; forms cloud condensation

what can dimethyl sulfide be converted into in the atmosphere?

sulfur trioxide and sulfuric acid

what human activities impact affect SO2 production and the sulfur cycle

during coal and fossil fuels, produce gasoline and heating oil, convert sulfur containing ore tino copper, lead, and zinc

how does sulfur dioxide affect the environment

toxic to plants, when oxidized in the atmosphere to sulfuric acid becomes the main component of acid rain