Definitions: Module 16-20

Question 1

soil

Answer 1

• a natural body consisting of layers, horizons and/or organic material of variable thickness
• differs from parent material by its morphology, chemical and physical properties, its mineralogy, and its biology

Question 2

soil profile

Answer 2

• a vertical arrangement of all the soil horizons down to the parent material
• known as bedrock

Question 3

soil horizon

Answer 3

a layer of mineral, organic soil or soil material approximately parallel to the land surface and has characteristics representing alteration by soil formation processes

Question 4

topsoil

Answer 4

• outermost layer of an organic soil and is made up of organic matter, mineral particles, and an interactive food web
• area of intense biological activity
• crucial for the cycling of nutrients

Question 5

soil texture

Answer 5

size of grains

Question 6

grains

Answer 6

small fragments produced by the weathering of rocks

Question 7

soil porosity

Answer 7

determines how air and water can travel between soil particles

Question 8

nutrient

Answer 8

any chemical required for the proper functioning of living organisms

Question 9

nutrient holding capacity

Answer 9

soil’s capacity to bind and hold nutrients

Question 10

water holding capacity

Answer 10

soil’s capacity to bind and hold water

Question 11

leaching

Answer 11

process by which materials are removed from the soil by water

Question 12

groundwater

Answer 12

this is the water contained within the saturated zone of soil

Question 13

water table

Answer 13

boundary between saturated and unsaturated zone of soil

Question 14

infiltration rate

Answer 14

speed at which water can percolate into the ground

Question 15

evaporative water loss

Answer 15

depth of water lost from the soil through evaporation

Question 16

aquifer

Answer 16

layer of porous rock/sediment that can hold and transmit water

Question 17

aquiclude

Answer 17

layer of non-porous rock/sediment that can hinder water movement

Question 18

salinization

Answer 18

accumulation of salts in and out on soil to the point where plant growth is suppressed

Question 19

desertification

Answer 19

• the deterioration of land in arid, semi-arid, and dry subsumed areas
• largely due to changes in Earth’s climate and human activities
• made worse by salinization

Question 20

splash erosion

Answer 20

soil gets compacted as drops of rainfall his the bare soil

Question 21

fluxes

Answer 21

• transfers of material between compartments
• occur at specific rates
• vary over time

Question 22

nutrient budget

Answer 22

quantitative estimate of rates of nutrient input and output to and from an ecosystem and within the system

Question 23

sources

Answer 23

compartments that release their nutrients faster than they get replenished

Question 24

sinks

Answer 24

accumulate nutrients at a faster rate than they release them

Question 25

eplimnion

Answer 25

shallow, wind stirred portion of the lake, depth determined by strength of wind

Question 26

metalimnion

Answer 26

below epilimnion, thermocline is located here, depth at which temperature decreases rapidly

Question 27

hypolimnion

Answer 27

deep, cold portion of the lake

Question 28

eutrophication

Answer 28

• a natural process taking place in water bodies
• characterized by a development towards an environment rich in nutrients and increasing primary productivity
• this process may take years to develop

Question 29

ecosystems

Answer 29

a community of different species interacting with one another an with their environment in order to sustain their grouping

Question 30

ecotones

Answer 30

• a transitional region between different ecosystems
• shares many of the species and characteristics of both ecosystems
• may also contain unique conditions
• greater biodiversity

Question 31

biomass pyramid

Answer 31

• this pyramid considers the total mass of all members of an ecosystem
• as we move up the pyramid to higher levels, the efficiency to energy conversion decreases

Question 32

trophic level

Answer 32

• each level of a pyramid
• each one has all the organisms in the food web that are the same number of feeding levels away from the original source of energy

Question 33

food chain

Answer 33

• represents a single feeding relationship
• starting from original source of energy to highest trophic level
• energy flows linearly in one way direction
• heat is lost at every conversion

Question 34

first law of thermodynamics

Answer 34

energy is neither created nor destroyed

Question 35

second law of thermodynamics

Answer 35

any energy conversion leads to less usable energy than initially

Question 36

biodiversity

Answer 36

the sum of all organisms in the area

Question 37

point source

Answer 37

specific spot where large quantities of pollutants are discharged

Question 38

none-point source

Answer 38

diffuse source of pollutants

Question 39

non-persistent pollutants

Answer 39

these pollutants can be broken down by chemical reactions or by bacteria into simple substances

Question 40

persistent pollutants

Answer 40

these are substances that degrade very slowly or cannot be broken down at all

Question 41

biochemical oxygen demand (BOD)

Answer 41

• measure the amount of oxygen consumed by microbes as they break down organic mater within water samples
• part of water quality testing

Question 42

assimilative capacity

Answer 42

• capability of streams to degrade organic waste

- varies from stream to stream

Question 43

sediments

Answer 43

rock and mineral fragments from gravel particles less than 2 millimetres in diameter, to finer sand, silt, and clay particles