Final Exam

Question 1

Describe how pH could affect the behaviour of cationic contaminants in soils?

Answer 1

High pH more binding

Question 2

Describe how pH could affect the behaviour of anionic contaminants in soils?

Answer 2

High pH less binding/sorption

Question 3

How does OM in soils affect the binding of cationic/anionic contaminants?

Answer 3

OM incr. cationic binding

Question 4

How does OM in soils affect the binding of hydrophobic organic chemicals?

Answer 4

Because it has uncharged domains it affects hydrophobic chemicals.

Question 5

Explain how increasing pH affects soil surface charge..

Answer 5

pH affects soil surface charge through de-protonation of OM and edges of clay minerals. If surface becoming more negative, the anionic containments get bound even less strongly so they get repelled from surface more. If pH is low and the negative charge is low, anions will bind more strongly.

Question 6

What might control the bioavailability of a poly-aromatic hydrocarbon (PAH) in soil?

Answer 6

OM sorption of metals

Question 7

What might control the bioavailability of PCBs in soil?

Answer 7

PCBs sorbed by uncharged OM

High Kow/benzine rings

Question 8

Why do we analyse blank samples in the lab?

Answer 8

to determine any contamination or ambient concentrations in the laboratory that may affect/confound results.

Question 9

Why do we filter and acidify water samples before metal analysis in the lab?

Answer 9

to remove particulate matter and to ensure non-degradation and also to ensure non-adsorption of the metals to the container

Question 10

Replication gives us a good way to measure accuracy of chemical analyses? T/F

Answer 10

False

Question 11

Replication gives us a good way to measure precision of chemical analyses? T/F

Answer 11

True

Question 12

Using Cr as an example, explain how redox is important in affecting contaminant mobility in the soil.

Answer 12

Redox affects Cr
as Cr6 —> mobile & toxic
Cr3 - immobile and non-toxic

Question 13

Using As as an example, explain how redox is important in affecting contaminant mobility in the soil

Answer 13

answer

Question 14

Which of the following species of Cu is most toxic?

Answer 14

Cu-DOM
Cu0
Cu2+ —> free copper ion
CuCl3-

Question 15

Explain how you might measure the partitioning coefficient for a metal in soil?

Answer 15

Contaminant in solution
mix with soil at incr. concentrations
measure

Calculate Kd
Kd kg/L = solid phase [contaminant]/solution phase [contaminant]

also can do;
total phase [contaminant]/solution phase [contaminant]

Question 16

Explain how you might measure the pKa for a chemical?

Answer 16

Ka = products/reactants
pKa= -log(Ka)
or 1/2way dissociation point

perform titration to produce curve
equivalence point between two inflection points is pKa

Question 17

Explain how you might measure the partitioning coefficient for a chemical in soil?

Answer 17

Contaminant in solution
mix with soil at incr. concentrations
measure

Calculate Kd
Kd kg/L = solid phase [contaminant]/solution phase [contaminant]

also can do;
total phase [contaminant]/solution phase [contaminant]

Question 18

An organic acid has spilled at the Urrbrae Wetland. The chemical has a pKa of 9.2 and pH of water and sediments is 6.5. What form is contaminant likely to be in? Is it more likely to partition to water or to the sediment? Will it bioaccumulate easily?
What if pKa is 3.2 and pH is 7.0?

Answer 18

pKa>env= unionised/undissociated (uncharged)

pKa

Question 19

Lead has spilled into a small farm dam, and the [Pb] is 0.6 mg/L. The sediment has a Kd value of 200 for Pb - what concentration do you expect in the sediment?
What if [Pb] is 6 mg/L?

Answer 19

Kd = solid/solution
200 = solid/6
=

Question 20

Copper sulphate has been used in a small farm dam to control algae, and the [Cu2+] is 1 mg/L. The sediment has a Kd value of 500 for Cu2+ - what concentration do you expect in the sediment?
What measurements might you need to take on the water to determine the PEC to examine if a risk is potentially present?

Answer 20

Kd = solid/solution
500 = solid/1
= 500

Need to measure free Cu ion
Or can measure DOM in water, know total Free Cu. and use model to predict free Cu.

Question 21

Analysing [Cu] in river waters or dam waters by inductively coupled plasma mass spectrometry is a good way to determine how toxic the Cu might be. T/F?

Answer 21

False - complexed by organic (Fe?) so not as free Cu

Question 22

Using examples, discuss the differences between:

• Acute and chronic toxicity
• EC50 and NOEC
• Hazard quotient and PNEC
• Free metal cation and complexed metal cation
• Hydrophobic and hydrophilic
• Antagonistic and Synergistic
• Accuracy and precision

Answer 22

• Acute and chronic toxicity:
• EC50 and NOEC:
• Hazard quotient and PNEC:
• Free metal cation and complexed metal cation:
• Hydrophobic and hydrophilic: water-hating & water-loving
• Antagonistic and Synergistic: interaction between contaminant mixtures (incr.=synergistic, decr.=antagonistic)
• Accuracy and precision:

Question 23

You have received sediment and soil samples from a client to analyse for inorganic element concentrations. The client would like to know total
concentrations for the following elements present in the samples at mg/kg
concentrations - iron, calcium, sodium, potassium, sulfur, manganese; and
µg/kg concentrations - cadmium, arsenic, copper and zinc. What information
can you supply to the client on the digestion and instrumental analysis
techniques that will be used to determine all these elemental concentrations?

Answer 23

Acid digestion - use strong acids to digest samples to get into correct form for ICP-OES for [high] or ICP-MS for [lower].

Also, expecting to see measures of contamination through analysis of blanks.
Use replication in the lab & accuracy assessment through digestion of a certified reference material (CRM).

If pesticides in water body - use HPLC, GSMS, LCMS.
If pesticide is difficult to make volatile during analysis, must use liquid chromatography and either UV detection or mass spectrometry detection.
If it is easily made volatile can use GC or MS or absorption UV/Infra-red

1st days lectures - davina. Analysis methods.

Question 24

You have been asked to develop a risk assessment for contaminants in agricultural fertilisers. Describe the steps you would take to carry out this risk assessment.

Answer 24

First need to know:
1. what rates are fertiliser used
2. what are contaminants in the fertilisers being used
Need this to determine a Predicted Env. Concentration (PEC).

To do a risk assessment, need PEC and PNEC:
Go to literature and find ecotoxicity threshold values for those contaminants in those soil type/s. If rare/few toxicity data (e.g. Yttrium) might have to use assessment factor to come up with PNEC.
If get enough data can do species sensitivity distribution and use HC5 and do risk characterisation as a hazard quotient for all contaminants.
If HQ>1 = will have to look at reducing the primitive level in the fertiliser.

Do a risk pathway analysis also.

Question 25

You have been asked to review a report for the Minister. The report has
examined the concentrations of heavy metals and PAHs in soil at a
contaminated site, due to be redeveloped for housing and with possible
impacts on human health. Several contaminants exceed the (human) health
investigation levels (HILs) for that land use and the Minister is concerned
about the Advertiser conducting an investigation of the contamination and
printing an inflammatory article that “people will die!!”. Write dot point
briefing notes for the Minister to help him understand the issue and to assist
his response to any media enquiries (10 marks)

Answer 25

HIL/EIL is investigation level only, does not mean people or organisms will die.
HIL is first part of screening process
Exceedance of an HIL does not imply health affects on individuals
Speciation
Exposure pathways
QA of report was right - good QA
were samples taken correctly - QA of Lab analysis etc

Question 26

Sediments in the Torrens River are contaminated by an agricultural pesticide
used in the parklands. Design an ecotoxicological monitoring study to assess
the impact of a sediment-bound pesticide in the Torrens?

Answer 26

Most likely an organic chemical. Want to know:
half life
pKa (if ionisable)
Kow (is it bio-accumulative, or in sediment or water column/solubility) - If sediment bound - likely high Kow.

Might want to measure/predict concentration of pesticide in sediments
What is environmental dose we’re discussing?
Find out what is PNEC?
is there literature data on toxicity of this pesticide to sediment-dwelling orgs?
collate literature data
produce SSD
Produce HC5 –> becomes PNEC
Compare PNEC & PEC.

If no data, must do ecotoxicity experiments.
design experiment using uncontaminated sediment with increasing doses of pesticides & comparing effects of sediment-dwelling organisms to produce site-specific PNEC.

Question 27

You work for the South Australian Environmental Protection Agency and a
developer wants to develop an old leather tannery site (with chromium
contamination of soils) for residential housing. What information would you
want to see regarding the contamination at the site, what would advise the
developer, and what are the key issues to consider with this proposal?

Answer 27

Want to see data of speciation, as it is critical for Cr (i.e. Cr 3 vs Cr6)

If Cr3 (harmless and immobile) = no worries mate. Compare against HIL for Cr3, stay below limit —> OK.

If Cr6 (carcinogenic and mobile) = and good to go
>HIL—> need to consider remediation
e.g. turn Cr6 to Cr3—> reductive remediation strategy

Question 28

You are a consultant and have been given the choice of 3 remediation options
for an old smelter site with arsenic, lead and zinc contamination.
1) In situ fixation
2) Phytoremediation
3) Soil washing
What is your recommendation and what are the main issues with the other two types of remediation strategy?

Answer 28

1) In situ fixation
Cheap
Don’t take contaminant away, just reduce bioavailability
Need to make sure doesn’t become available again.

2) Phytoremediation
Can remove contaminant
Slow
Only removes to depth of roots
Restricted by climatic variables and access for agricultural machinery for seeding/planting etc
Contaminants can be accumulated in wood that can be used as fuel; the pollutants collected in leaves can be released again into the environment during litter fall.

3) Soil washing with acids
Removes contaminant (may have to use multiple extractants to remove multiple contaminants) (sequential washing)
Soil generally not fit for growth after washing with acids
Highly destructive - removes coarse soil from fine soil (where contaminants tend to sorb). This fraction must then be further treated using other technologies…
However, it can be difficult to remove organic contaminants sorbed onto clay particles!

Question 29

The recent floods in Adelaide washed significant quantities of storm water into
the River Torrens. A fish kill was noticed 2 days later. You work for the EPA
and have to investigate this issue. Describe your investigation plan.

Answer 29

1. Histology - take sample of dead fish to determine mode of uptake, or detect chemicals in major organs
   e. g. affect respiration, accumulated in kidney and liver, something induced metallothionine.
2. Take water samples - are there metals or organics in the samples?
3. Once ID, check published toxicity levels to determine PEC/PNEC (although not predicted, its measured)

Question 30

Record hot temperatures in Adelaide have caused a series of electrical
substations to overheat and many transformers have split and leaked
polychlorinated biphenyls (PCBs) onto soils. What is your sampling, analysis
and remediation plan for these areas?

Answer 30

PCB - lots of chlorine groups, and poly aromatic rings
high Kow
Sorbed strongly to soil
Not suitable for bioremediation
Best suited to removal by solvent extraction, or thermal decomposition (e.g.

Sampling plan -
targeted sampling plan with gradient away from transformers down slope to look for contaminated soil
anything above HIL take away for remediation

Question 31

A smelting company wants to set up a copper (Cu) smelter at Murrray Bridge
and discharge waste effluent (containing Cu) to the river. You are hired as a
consultant to develop an effluent discharge permit setting maximum permitted
concentrations of Cu in the effluent. How would you go about this?

Answer 31

Cu binds strongly to DOC in water/complexed
In effluent, likely to be free Cu, but must now speciation, and [Cu] in effluent
what is discharge volume vs flow rate of river to calculate a dilution factor (DF)
need to develop risk ass.
need PEC and PNEC
PEC=dilution + speciation (to determine free Cu)
PNEC=look at literature and find HC5 for a range of sp. that are relevant to Murray river; set site-specific PNEC for Cu

Then, knowing volume & speciation of effluent and also DOC of river, can calculate speciation of Cu, given that dilution
compare PEC based on free ion to PNEC based on free ion.

Question 32

The volcanic eruption from Mount Kelud in Indonesia has caused a thick layer
of ash high in arsenic (As) to be deposited on Mbalak Village. How would you
develop an ecological risk assessment for this situation and what are the likely
issues with As contamination. How would you remediate this and what
conditions do you need to ensure effective remediation?

Answer 32

As is redox-sensitive (speciation is important)
Need to consider dilution in the env. (is dust incorporated in the soils over time, whether thru microbes, earthworms etc, or agricultural activities) - can you calculate a dilution
Need to develop a PEC/PNEC
PEC=need to know how much dust; [As] & speciation; and assumed DF in soil –> to give PEC in soil
PNEC=in literature—> SSD —>

if no data —-> need to conduct ecotox experiments, use ag. crops to develop site-specific PNEC (as Ag. area).

Do risk-assessment
HQ

Question 33

You have been employed as a consultant by the Queensland Environmental Protection Agency to advise them on the fate of pesticide spilled into a
stream in an area surrounding a pesticide manufacturing site in Queensland. How would you approach this problem?

Answer 33

What is pesticide?
What is structure?
Organic contaminant —> key things are that involve their fate:
vapour pressure
pKa (is it ionisable?)
half-life
water solubility/Kow
if high, in sediments not H2O —> sediment-
dwelling orgs. most affected/susceptible,
probably a little way downstream of spill.
If low Kow, probably in water column, much
further downstream, and mostly only sampling
water. Therefore PNEC based more on
fish s.p that are surface dwelling rather than
soil/benthic dwellers as highly water soluble
due to low Kow.

Then need to do SSD, HC5, HQ

Question 34

You are a consultant and have been given the choice of 3 remediation materials to remediate Zn contamination in soil at an industrial site by in situ fixation. What characteristics are you looking for in the materials to be effective in binding Zn. How would you test in the laboratory the ability of the materials to bind Zn and render it less available? What quality assurance/quality control measures might be needed in those laboratory tests?

Answer 34

Zn is a cation
Characteristics of a material to bind Zn need to be negative charge as measure by CEC (high CEC)
Or can use a material to precipitate the metal.

Sorb=Kd Prac e.g. Measure Kd on binding material, and then measure Kd of binding material with various mixes of the soil to determine the correct amount to add.
What QA you need in those lab tests?
Precision, CRM, correct analysis of Zn.

Question 35

Oil has been discovered in northern South Australia. If an oil spill occurred in the desert in northern South Australia, how would you design a remediation
program to clean up the spill? Write technical advice briefing points for the SA EPA regarding a remediation plan.

Answer 35

Oil - amenable to bioremediation

Dry - going to need water to facilitate microbial processes

Question 36

HP Billiton wants to open up a new mine in the south-east of South Australia near Mount Gambier to mine chalcopyrite - copper iron sulfide (CuFeS2). What issues might be generated by wastes from this operation and how could they be managed?

Answer 36

Issues generated by wastes:

Acid Mine Drainage

Question 37

The River Torrens has suffered an outbreak of algal blooms again this summer. Orthophosphate ion (H2PO4-) has been identified as one of the pollutants leading to this situation. Describe a sampling and analysis plan to identify the source of the pollutant and write a possible remediation plan for the water – what remediation processes would need to be used to clean up the water?

Answer 37

where did bloom first occur?
Sampling quite a way upstream to determine if point source pollution e.g. sewage plant
If this is the case, will need to put in place some controls for discharge into river.

to remove OrthoP – negatively charged, so can use anion exchange on a positively charged surface e.g. sorption using remediation medium that has net positive charge to adsorb the P
can tip something in the river to either sorb or precipitate e.g. Phos-lock (lanthanum phosphate is extremely insoluble, and precipitates P{ out of sediment.)

Question 38

What is PEC? How do you find it & what do you use it for?

Answer 38

Predicted Environmental Concentration

Answer

Question 39

What is PNEC? How do you find it &; what do you use it for?

Answer 39

Predicted No Effect Concentration
The concentration at which the toxicant will have no environmental effect
Answer

Question 40

What’s biomagnification?

Answer 40

where contaminant concentration increases as you move up trophic levels
concentration in predator>prey

Question 41

What is bioaccumulation?

Answer 41

accumulation in organisms through membranes, or diet

Question 42

What is pathway analysis in environmental risk assessment?

Answer 42

All exposure pathways and the fate in the environment

Question 43

Describe what a species sensitivity distribution is.

Answer 43

species sensitivity distributions (SSDs) are models of the variation in sensitivity of species to a particular chemical or toxicant. Can use HC5 from SSD and do risk characterisation as a hazard quotient for all contaminants.

Question 44

What are the key features of a single species ecotoxicity test and what are the quality assurance and quality control issues that need to be considered in
performing ecotoxicity tests?

Answer 44

answer

Question 45

In dealing with ecotoxicity data in ecological risk assessment, what is an assessment or safety factor used for?

Answer 45

answer

Question 46

The risks to humans of measured concentrations of pharmaceuticals in water
are huge. TRUE or FALSE?

Answer 46

False

Question 47

What is histopathology?

Answer 47

Histopathology is looking at morphology and changes in organs

Question 48

What are the two methods for production of nanoparticles?

Answer 48

Top down synthesis:
implies that the nanostructures are synthesized by removing crystal planes which are already present on the substrate.
An approach where the building blocks are removed from the substrate to form the nanostructure.

Bottom up synthesis:
nanostructures are synthesized onto the substrate by stacking atoms onto each other, which gives rise to crystal planes, crystal planes further stack onto each other, resulting in the synthesis of the nanostructures.
An approach where the building blocks are added onto the substrate to form the nanostructures.

bottom-up approach is more advantageous than the top-down approach because there’s a better chance of producing nanostructures with less defects, and more homogenous chemical composition.

Question 49

What are the special features of nanoparticles that make them potentially
harmful contaminants?

Answer 49

Small size = likely to be more mobile in water, soil (can move through pores), and air
large surface area
highly reactive

Question 50

Do you think species sensitivity distributions are useful methods to summarise
ecotoxicity data? Discuss why/why not.

Answer 50

Yes: because you’re summarising lots of toxicity data for multiple sp.
Get a better representation of the ecosystem where same multiple sp. present
Can have sliding protection scale values for different land or water uses - good for policy makers to choose what level of protection
Incorporates uncertainty - less sp= greater confidence intervals & the more protective because you’ve taken the 95th percentile.

Question 51

What is the principle of bio-piles or composting for remediation? What
contaminants are suited for treatment by this technique?

Answer 51

Using thermal and microbial degradation to remove contaminant,
organic chemicals best suited to this technique, but some org. chem. are resistant to degradation by microbes - e.g. poly-chlorinated bi-phenols sticking so strongly to the solid phase
best for non-aromatic contaminants e.g. oils, greases, diesel, petrol (not poly-aromatic)

Question 52

Describe a typical toxicity test and the data that this provides

Answer 52

answer

Question 53

Do you think NOECs are useful ecotoxicity thresholds to use for risk assessments of chemicals? Discuss why/why not.

Answer 53

Disadvantage:
Defined by doses chosen by experimenter
May be unbounded if experimenter hasn’t done appropriate range-finding test.

Question 54

What is hormesis?

Answer 54

Draw graph and mark hormesis.

Question 55

Define the following terms:

a) Endocrine disruption;
b) Histopathology;
c) Biomarker; and
d) HBIL.

Answer 55

a) Endocrine disruption;
b) Histopathology;
c) Biomarker; and

d) HBIL/HIL
Health Investigation Levels

Question 56

Easyclean Pty Ltd, a phytoremediation company, has suggested they can clean up the Brukunga mine site of heavy metals using their phytoremediation technology using hyperaccumulator plants. What is your advice to DMITRE and how did you come to that reasoning?

Answer 56

Disadvantages: Slow, limited to surfaces, huge accumulation of waste rock.

Question 57

You have been hired as an expert in remediation by M&M Pty Ltd to clean up an old petrol station with an electricity substation contaminated by polychlorinated
biphenyls (PCBs) and fuel oils. There is shallow groundwater at the site and nearby residents use the aquifer for drinking water – is the groundwater at risk? How would you evaluate that? How would you remediate this site?

Answer 57

PCB sorb really strongly to soils and sediments (high Kow). very unlikely to find in water. Fuels oils as well - hydrophobic.

PCB - thermal
Fuel oils - bioremediation