Soil

Question 1

Fulvic acids

Answer 1

organic acids found in soils derived from organic matter decomposition
- smaller than humic acids, soluble in water, more OH and COO- groups
- strong chelating agents, determine soil acidity

Question 2

4 functions of soil

Answer 2

plant growth medium
water storage, supply, and purification
modifier of the atmosphere
habitat for organisms (decomposers)

Question 3

Soil water

Answer 3

mediates organic and inorganic components with microbes
- site of redox, acid-base reactions

Question 4

Clay

Answer 4

<2um
- site of chemical reactions in soil

Question 5

Sand

Answer 5

20-200um

Question 6

Silt

Answer 6

2-20 um

Question 7

Loam

Answer 7

mixture of silt, sand, and clay
- high nutrients, moisture, and humus

Question 8

Formation of soil

Answer 8

CLORPT
Climate
Topography (Relief)
Organisms
Parent Material
Time

Question 9

Colloids

Answer 9

clay particles, mixture that has particles between 1-1000um, evenly distributed

Question 10

Koalinite

Answer 10

hexagonal sheets, clay mineral

Question 11

cation exchange capacity

Answer 11

capacity for soil to exchange nutrients with plants
- important for farming
- determined by amount of clay and/or humus present
(meq/100g dry soil)

Question 12

humic acids

Answer 12

larger, fewer COOHs, soluble in bases (not water) because they become deprotonated

Question 13

liming

Answer 13

adding CaCO3 to soils to partially neutralize soil acids

Question 14

Kow

Answer 14

octanol-water partition coefficient
- high Kow = deposit in sediments rather than water and bioaccumulate
- hydrophobic (and/or very large) organic substances

Question 15

chelation

Answer 15

“binding” of heavy metals onto folic acids

Question 16

mineralization

Answer 16

cell metabolism wastes are deposited into the soil by microbes

Question 17

immobilization

Answer 17

microbes complex molecules from the soil and use them for cell metabolism

Question 18

nitrification

Answer 18

ammonia/nitrite is oxidized into nitrate by nitrifying bacteria (NO3- -> NO4-)

Question 19

Denitrification

Answer 19

nitrate is converted into nitrogen gas by denitrifying bacteria

Question 20

Paddy soil

Answer 20

used for rice farming
- anthrosoil: flooded and drained repeatedly
- this cycle produces hydromorphic soil which causes iron toxicity to fish and aquatic life
- flooded: low O2, reduces iron species into toxic molecules
- drained: high O2, iron species precipitate and suffocate fish

Question 21

Rhizosphere

Answer 21

where microbes and plants work to fix nitrogen in the soil
“root microbiome”

Question 22

Benthic

Answer 22

bottom of a body of water

Question 23

Pelagic

Answer 23

relating to open ocean

Question 24

nitrogen-fixing bacteria

Answer 24

take N2 and make ammonia
ammonification

Question 25

nitrifying bacteria

Answer 25

nitrification = ammonia -> nitrites (-> nitrates)

Question 26

byproducts of nitrification/denitrification:

Answer 26

NO and N2O gases
- N2O: insoluble in water and unreactive, very strong CFC/GG

Question 27

saline soil

Answer 27

high salt content (high ion content)

Question 28

sodic soil

Answer 28

high NaCl content

Question 29

calcareous soil

Answer 29

high CaCO3 content, fairly highly oxidized species and high pE

Question 30

hydromorphic soil

Answer 30

excess water, low Eh, lack O2