contaminant behaviour, lectures 1 and 2

Question 1

ways in which contaminants reach groundwater

Answer 1

river infiltration
lak infiltration
vadose zone leaching
direct injection

Question 2

9 contaminants

Answer 2

organic material
fecal pollution
nutrients
radioactive material
trace metals
DOM
acid rain 
nitrate
salinisation

Question 3

3 contaminants that are different for ground water

Answer 3

DOM, already has naturally low O2
nutrients, only N is bad, P adsorbs
acid rain- rock buffer

Question 4

what is advection

Answer 4

transport by the bulk movement of the flowing groundwater, at an average rate= average v of groundwater

Question 5

what is the other transport process called

Answer 5

hydrodynamic dispersion

Question 6

definition of hydrodynamic dispersion

Answer 6

process by which the contaminant spreads away from the direct advection path

Question 7

three processes of hydrodynamic disperion

Answer 7

differential movement across channel area

difference in pore sizes, channeling solutes

molecular diffision

Question 8

draw each of those processes, plus the tracer column, and the 2d dispersion of a continuous and point source

Answer 8

ok

Question 9

what make good tracers

Answer 9

stable unreactive (conservative ) chemicals,

chloride
nitrate
boron
caffiene

Question 10

what is the simplest option for modelling

Answer 10

assume chemical behaves conservatively
goes with the flow
dilution and dispersion

Question 11

retardation can be due to

Answer 11

die off
radioacrtive decay
chemical break down
adsorption by host rock

Question 12

attributes of bacteria

Answer 12

large
adsorb to minerals
survive days to weeks

Question 13

attributes of viruses

Answer 13

weeks to months

very small

Question 14

protozoa

Answer 14

complex life-cycle
resistant in some stages of life-cycle
large
weeks to months

Question 15

what is the distribution coefficeint

Answer 15

K=S/c

=host rock contam conc/ contam conc

Question 16

what can rock interaction do with water (4)

Answer 16

buffering, PH and carbonate chemistry

host rock redox control

form new precipitates

adsorption of minerals to rock

Question 17

draw carbonate and carbonic acid reactions, and fractrion curve for them

Answer 17

ok

Question 18

draw oxidisation graph, with upper and lower limits of water

Answer 18

ok

Question 19

why and what controls redox reactions

Answer 19

fe and mn because 02 so low

Question 20

example reaction for precipitation

Answer 20

cu2+ +s-2= CuS K=aCu2+.aS-2

Question 21

example of adsorption of cu2+

Answer 21

Cu2+ +mineral—OH = mineral—)Cu+ +H+

Question 22

what can be a problem of adosrption/precipitation

Answer 22

creates reservoirs

Question 23

examples of chemicals that reduce states

Answer 23

metals
sulphate to H2S
Nitrate (denitrification)

Question 24

what isnt as important for gw

Answer 24

temp, PH BOD etc, ecology limited

Question 25

contaminant transport modelling software

Answer 25

SEEP2D

Question 26

how does arsenic come about

Answer 26

aluvial deposists formed from arsenic unit

reducing conditions release AS from fe oxides

Question 27

how does arsenic come about

Answer 27

aluvial deposists formed from arsenic unit

reducing conditions release AS from fe oxides

Question 28

where is the case study with the three options

Answer 28

cheviot

Question 29

options 1 to 3

Answer 29

treat turbidity and pathogens

dig bigger one 40 meters, treat less

160 m, dont treat at al

Question 30

why is nitrogen bad

Answer 30

drinking water quality
nutroient inrichment, eutrophication
indicator of other ag chemicals

Question 31

what happens with increased residence time

Answer 31

older aquifers, land use changes havnt reached it yet

although o2 tends to be less, so more amonia and less nitrates because its an anoxic environemnt so even if it does reach, it will be denitrified.