Final Exam Flashcards

Question

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 1

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

Answer 2

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.

Answer 3

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

Answer 4

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!

Answer 5

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)

Answer 6

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

Answer 7

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.

Answer 8

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

Answer 9

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

Answer 10

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.

Answer 11

Oil - amenable to bioremediation | Dry - going to need water to facilitate microbial processes

Answer 12

Issues generated by wastes: | Acid Mine Drainage

Answer 13

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.)

Answer 14

Predicted Environmental Concentration | Answer

Answer 15

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

Answer 16

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

Answer 17

accumulation in organisms through membranes, or diet

Answer 18

All exposure pathways and the fate in the environment

Answer 19

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.

Answer 20

Histopathology is looking at morphology and changes in organs

Answer 21

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.

Answer 22

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

Answer 23

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.

Answer 24

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)

Answer 25

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

Answer 26

Draw graph and mark hormesis.

Answer 27

a) Endocrine disruption; b) Histopathology; c) Biomarker; and d) HBIL/HIL Health Investigation Levels

Answer 28

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

Answer 29

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

Final Exam Flashcards

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