Organic Contaminants

Question 1

Advantages of Pesticides

Answer 1

Only small amount needed to be effective
Low toxicity to non-target species
degrades to benign products
does not accumulate
does not run off with water
pests are slow to develop resistance

Question 2

Disadvantages of Pesticides

Answer 2

inorganic based

Very toxic to humans

Not biodegradable

Question 3

DDT

Answer 3

affects neurons and wildlife
DDT -> DDE and DDD
DDE - affects eggshell => birth rate
DDE & DDD persistent and Lipophilic

Question 4

Organo Phosphates

Answer 4

Parathion & Malathion
Parathion
- toxic to non-target species
- absorbed through skin and membranes
- -> paraoxon which causes headaches, convulsions =, vomit, diahorrea …

Question 5

Pyrethroids

Answer 5

Natural
attack nervous system
harmless to humans
Non selective
pollutes aquatic environments

Question 6

Triclosan

Answer 6

Antimicrobial
blocks fatty acid production
non toxic to humans (but resembles estrogen)
lipophilic
stable
toxic to algae
in water and cannot be easily removed

Question 7

PFCs: PFOs

Answer 7

fabric and fire protector
persistent and bioaccumulating
toxic to mammals

Question 8

Endocrine system and disruption

Answer 8

Hormone producer
transfer information around the body
hormones only affect the parts of the body they are genetically programmed to affect

chemicals can mimic hormones
stimulates body at the wrong times
blocks the actual hormones and their effects
cause over or under production of hormones

Question 9

solubility thresholds

Answer 9

High > 100 mg/L
Low < 10 mg/L

Question 10

Kow thresholds (octanol-water ratio)

Answer 10

< 3 - in water
>3 - in soil

Question 11

Bio concentration factor

Answer 11

low tendency < 100
High tendency > 5000

Question 12

Vapour pressure - KH

Answer 12

kH > 100
kH < 100

Volatile > 0.01 kPa
Not volatile < 0.01 kPa

Question 13

Persistence

Answer 13

DT50 > 2 month - water

DT50 > 6 month - soil/sediment

Question 14

Ionisation

Answer 14

pH > pKa - major ionisation
pH < pKa - minor ionisation

Question 15

Discolour tap water and Mn & Fe

Answer 15

Fe forms oxides and rust
Mn (II) is soluble in water and difficult to remove

Question 16

Mn Pathways into water

Answer 16

Runoff - particulate matter
Local geology weathering into water
Soils can release Mn with help of organic matter

Question 17

health impacts of Mn

Answer 17

chronic exposure in adult - manganism like parkinsons
Chronic exposure in children - decrease intellect and hyperactivity

Question 18

Mn, reservoirs & the season

Answer 18

thermoclien created in summer which prevtns circularion of deep water
O2 depletes - Mn from soil can then enter water ways
in autumn the thermocline breaks and the Mn in mix through the entire water body

Question 19

Climate change and Mn

Answer 19

reduces amount of water -> less dilution
decreases DO => algal blooms

Question 20

Solutions to reduce Mn and Fe

Answer 20

Resmix - mixes water
HOx system - reduces Fe
Water lifting aerators - prevents hypoxia

Question 21

Future impacts of Mn on Water

Answer 21

Scottish pipes still have lead traps in H3PO4
Mn will displace and mobilise the lead

Question 22

What are nanoparticles

Answer 22

one dimension is 1-100 nm
metallic elements
their concentration is increasing everywhere in the environment

Question 23

characteristics of nanoparticles

Answer 23

Diameter - affects binding energy & MP
Shape - sphere, rod, sheet = changes SA and solubility
Coatings - dictate environmental fate

Question 24

Type of nanoparticles (7)

Answer 24

inorganic
organic
carbon
composite
natural
incidental
engineered

Question 25

nano silver

Answer 25

USE: kill bacteria & prevent staining
enters environment via washing of clothes
looks like a protein so can get inside cells
indirectly impacts ecosystem function