Acid Mine Drainage ACD

Question 1

Issues

Answer 1

acidic - ochreous - pollution, run-off - abandone mining spoil tips, 9% surface, impacts - classified and unclassified H2O

Question 2

COAL

Answer 2

high C % complex structure, % small H, O, N. significant - S, P, trace metals. Partial decay - vegetation , anaerobic

Question 3

Anaerobic decay

Answer 3

low Eh and pH, CH2O decay => low Eh, organic acids form -> low pH

Question 4

Cellulose, lignin

Answer 4

Coal complexes

Question 5

Fe (3)

Answer 5

Reduced to Fe(2)

Question 6

Sulphate SO4 2-

Answer 6

reduced to S2-

Question 7

10% pyrite forms of coal seam

Answer 7

FeS.nH2O -> FeS2 (pyrite)

Question 8

Mining techniques: Drift mining 17th & 18th century

Answer 8

Outcrops mined inwards, coal seam, spoil tip dug out - wastes fall to bottom of hill

Question 9

Mining techniques: Longwall (Deep) mining 19th & 20th century

Answer 9

Pit dugs deeper than H2O table. Water pumped away

Question 10

Mining Modern Techniques: Opencast mining

Answer 10

Use of machines

Question 11

Coal Mining UK, AMD area Affected

Answer 11

central scotland, durham, south yorkshire, south wales

Question 12

Coal Mining UK, AMD area NOT affected

Answer 12

midlands, tyneside, lancs/merseyside

Question 13

AMD Unpredictable - Acidity

Answer 13

variable, pyrite content, rock type, catchment

Question 14

AMD Unpredictable - Rebound

Answer 14

variable rate, recahrge rate - physical structure, groundwater rebound

Question 15

AMD Unpredictable - Water course

Answer 15

recieving, volumes, dilution, hydrology

Question 16

Abandoned mines

Answer 16

Water pumping stopped, working can refill

Question 17

Leaky Buckets

Answer 17

water moves between workings, deep working can fill - no problem with AMO at surface, unexpected outflows at old mines if connection alter

Question 18

AMD Chemical Reactions 1

Answer 18

Pyrite + coal + oxygenated water - acid produced (4H+)

Question 19

AMD Chemical Reaction 2

Answer 19

Fe2+ + H2O -> Fe(OH)3 ochre + 6H+ more acid

Question 20

AMD Chemical Reaction 3

Answer 20

FeS2 + Fe3+ -> 16H more, This enchances (2) : autocatalytic

Question 21

Pyrite+ oxygenated water -> ochre + acid

Answer 21

oxidation rate a function of coal/pyrite surface area: spoil tip rapid conversion

Question 22

Bacteria

Answer 22

increase rate by 10^6

Question 23

Fe Impacts

Answer 23

100 mgdm^-3 in mine water -> EQS 1mgdm-3 visible, 5 mgdm-3 discoluration

Question 24

Precipitate Fe(OH)3 ochre

Answer 24

pH 4, affects flora (photosynthesis), fauna (invertebrate spawning), blankets river bed

Question 25

ACID

Answer 25

initial pH 1, catchment dependent - acid rock pH 1-3, basic rock 6-8, dissolves minerals CuFeS2, affects speciation (toxicity) Al

Question 26

Salinity

Answer 26

Extra TDS impacts flora & fauna - stress (cellular osmotic pressure change)

Question 27

Treatments: Physical

Answer 27

cascade oxidation, sludge settlement

Question 28

Treatments: Biological

Answer 28

bacterial oxidation, bioremediation, wet land remediation - reed beds, metal sorption

Question 29

Treatments: Chemical

Answer 29

neutralisation, metal adsorption