25114649
BEFORE THE EPA CHATHAM ROCK PHOSPHATE MARINE CONSENT APPLICATION IN THE MATTER of the Exclusive Economic Zone and Continental Shelf
(Environmental Effects) Act 2012 AND IN THE MATTER of a decision-making committee appointed to consider a
marine consent application made by Chatham Rock Phosphate Limited to undertake rock phosphate extraction on the Chatham Rise
__________________________________________________________
STATEMENT OF EVIDENCE OF DR NIKOLAUS HERMANSPAHN FOR
CHATHAM ROCK PHOSPHATE LIMITED
Dated: 29 August 2014
__________________________________________________________
__________________________________________________________
Barristers & Solicitors
J G A Winchester / H P Harwood Telephone: +64-4-499 4599
Facsimile: +64-4-472 6986
Email: [email protected]
DX SX11174 P O Box 2402 Wellington
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CONTENTS
EXECUTIVE SUMMARY ........................................................................................... 3
INTRODUCTION ........................................................................................................ 3
Qualifications and experience ........................................................................... 3
Code of conduct .................................................................................................. 4
Role in marine consent application ................................................................... 5
Scope of Evidence............................................................................................... 5
IMPACT OF RELEASE OF URANIUM INTO THE MARINE ENVIRONMENT DURING MINING OPERATIONS .................................................. 5
IMPACT OF NATURALLY OCCURRING RADIOACTIVE MATERIAL IN CHATHAM RISE PHOSPHATE RELEASED INTO SOIL BY APPLICATION OF PHOSPHATE ROCK FERTILISERS ........................................ 7
Radiological Protection in New Zealand ........................................................... 7
Radioactivity in New Zealand soils ................................................................... 7
Radioactivity in Chatham Rise phosphate rock .............................................. 8
Rate of application of uranium to agriculture soils ......................................... 8
Accumulation rate in soil .................................................................................... 9
Dose modelling .................................................................................................... 9
Results .................................................................................................................. 11
Assessment ......................................................................................................... 13
CONCLUSIONS ......................................................................................................... 14
SCHEDULE OF APPENDICES ................................................................................. 15
REFERENCES ........................................................................................................... 15
FIGURES .................................................................................................................... 16
APPENDIX A: ERICA ASSESSMENT REPORT ...................................................... 21
APPENDIX B: INFORMATION ON RESRAD ........................................................... 22
APPENDIX C: EXTRACT OF A RESRAD REPORT ................................................ 23
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EXECUTIVE SUMMARY
1. The focus of my evidence is on the radiological impact from mining and
use of Chatham Rise phosphorites as fertiliser. In particular I address:
(a) the radiological impact of mining on marine biota; and
(b) the radiological impact on the human population from application
of the fertiliser on agricultural soils.
2. Radiological impact on marine biota has been assessed with the use of
the ERICA tool. Risk to marine biota was found to be low in particular
because of short exposure times.
3. Uranium is expected to accumulate in agricultural soils from application of
uranium containing fertilisers.
4. Radiological impact on human population from accumulated radioactivity
was assessed with the use of RESRAD modelling software.
5. The most impacted population would be resident subsistence farmers who
live in a dwelling built on farmland receiving intensive application of
Chatham Rise phosphorite fertiliser. Modelling suggest that the
radiological dose to these individuals would remain below the international
guideline level of 1 mSv per year for greater than 250 years of intensive
fertiliser application. This period extends to 675 years at the lower
application rates in the second scenario described.
6. The general population would be affected to a lesser extent.
INTRODUCTION
Qualifications and experience 7. My full name is Nikolaus Helmut Hermanspahn.
8. I was awarded a Doktor der Naturwissenschaften (PhD in physics) by
Johannes Gutenberg Universität, Mainz, Germany.
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9. I am Senior Scientist with the National Centre for Radiation Science of the
Institute of Environmental Science and Research.
10. My principal role is that of team leader environmental radioactivity.
11. I have 13 years of professional experience in the field of environmental
radioactivity measurements, in the modeling of dispersion of radioactive
substances in the environment and in assessing impact of radioactive
contamination on the human population and the environment.
12. In particular, I have been responsible for the environmental radioactivity
monitoring programme for New Zealand which involves the determination
of low level radioactivity levels in environmental samples such as air,
rainwater and milk. I have been involved in studies on soil erosion and
sedimentation and have developed expertise the assessment of low level
airborne radioactivity for the purpose of detecting clandestine nuclear tests
as part of our international involvement in the monitoring network of the
Comprehensive Test Ban Treaty Organisation.
13. I have been involved in international projects on laboratory methods for
use in emergency situations (International Atomic Energy Agency) and in
the assessment of marine radioactive contamination (an international
project that was started in response to the Fukushima nuclear accident).
14. I hold two patents, have published 18 papers and am currently Receiving
Editor for Applied Radiation and Isotopes, an Elsevier publication.
Code of Conduct
15. I confirm that I have read the Code of Conduct for expert witnesses
contained in the Environment Court of New Zealand Practice Note 2011
and that I have complied with it when preparing my evidence. Other than
when I state that I am relying on the advice of another person, this
evidence is entirely within my area of expertise. I have not omitted to
consider material facts known to me that might alter or detract from the
opinions that I express.
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Role in marine consent application
16. I have prepared a report (FW14021) for the Ministry for Primary Industries
(MPI) entitled “Uranium in Chatham Rise Phosphate Rock”. This report is
Appendix A of the Crown's submission.
17. I also prepared a statement for Chatham Rock Phosphate Ltd (CRP) to
address the issues of whether the Chatham Rise phosphate rock is
radioactive material and what potential impact the release of radioisotopes
deposited during the era of atmospheric nuclear testing could have on the
marine environment. This statement was attached as appendix D to the
report by Golder Associates entitled “Review of Sediment Chemistry and
Effects of Mining”, which is appendix 11 to the EIA.
18. I also prepared CRP's response to address the DMC's 25 July 2014
request for further information about cumulative effects of potentially
increased radioactivity levels in soil from the application of Chatham Rock
phosphate as fertiliser.
Scope of evidence
19. In this statement, I describe:
(a) the potential impact of release of uranium into the marine
environment during mining; and
(b) modelling I have undertaken of the radioactivity of naturally
occurring radionuclides released in soils from fertiliser.
IMPACT OF RELEASE OF URANIUM INTO THE MARINE ENVIRONMENT
DURING MINING OPERATIONS
20. Uranium is a naturally occurring component of seawater and is found at
relatively constant levels in all oceans and at all depths. Uranium content
of seawater from the Chatham Rise was determined to be 3.5 µg/L,
consistent with uranium levels found elsewhere (Gascoyne 1992, and Mr
Kennedy's statement of evidence).
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21. During mining operations seawater is used to “vacuum” sediment and
phosphorites and is used as the medium to discharge waste. The mining
process therefore has the potential to result in a discharge with increased
level of dissolved uranium from the seabed sediments.
22. As per CRP's responses to request for further information: request no 8-11
and 16 and 19, the increase in uranium concentration in the near field
plume would be 0.21 mg/L.
23. We have assessed the impact of dissolved naturally occurring
radionuclides with the ERICA tool. The ERICA tool is a software system
that has a structure based upon the tiered ERICA integrated approach to
assessing the radiological risk to terrestrial, freshwater and marine biota.
24. For the purpose of this assessment the activity concentrations of uranium
daughter nuclides uranium-234, radium-226, lead-210 and polonium-210
were defined to be equal to uranium, giving an activity concentration of c
= 0.21 mBq/L for each isotope.
25. Based on the ERICA tool, we determined that the effect of a permanent
increase in concentration of uranium by 0.21 mg/L would have a small
effect on marine biota (see figure 1, ERICA report is attached as Appendix
A). For a conservative estimate, we included uranium decay products in
the assessment. Risk factors as determined by ERICA tool were in the
range 0.008 – 1.4. This implies very low risks to marine biota as risk
factors are normalised so that a risk factor of one would indicate dose at
the guideline value (10 µGy/hr1).The highest risk factor of 1.4,
corresponding to a dose rate of 14 µGy/hr was determined to be for intake
of polonium-210 by zooplankton. The concentration of polonium-210 is
estimated to remain within the range of the naturally occurring
concentration of 0.3-2.5 mBq/L (IAEA 1988) and the increase is
furthermore only of temporary nature. Concentration levels further away
from the mining site will be even further diluted and pose negligible risk.
11
Micro Grays per hour
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IMPACT OF NATURALLY OCCURING RADIACTIVE MATERIAL IN CHATHAM
RISE PHOSPHORITE RELEASED INTO SOIL BY APPLICATION OF
PHOSPHATE ROCK FERTILISERS
Radiological Protection in New Zealand
26. The deleterious impact of radiation on living beings is measured as dose
in units of Sievert (Sv). For radiation protection, the most relevant
quantities are effective dose for external radiation and committed dose for
ingested radionuclides, as these are directly related to health risk. In the
following the term dose refers to one of these terms or a combination of
these two dose terms.
27. The use of ionising radiation and radioactive material is regulated in New
Zealand by the Radiation Protection Act 1965 and the Radiation Protection
Regulations 1982. These do not apply to the mining or use of Chatham
Rise phosphorites as fertiliser, as Chatham Rise phosphate rock is not
radioactive material (Hermanspahn 2014). However, radiation protection
measures used to comply with these regulations can still provide a
criterion for what would constitute appropriate protection of the public in
terms of radiological impact including those dwelling on affected land.
28. Under New Zealand Radiation Protection Regulations 1982 activities are
deemed acceptable if the dose to any member of the public does not
exceed 5 mSv (milli-Sievert) in any given year. In practice a lower dose
limit of 1 mSv is now employed as recommended by the International
Commission on Radiological Protection (ICRP) (ICRP publication 103).
This dose limit of 1 mSv/year is used for the purpose of this evidence to
assess impact of the use Chatham Rise phosphorites as fertiliser.
Radioactivity in New Zealand soils
29. Dobbs & Matthews (1976) analysed 320 soil samples provided by the
DSIR Soil Bureau. In their paper they did not specify whether the soil
samples came from agricultural or undisturbed land. They determined the
radium-226 concentration in New Zealand soils to range from 4 – 56
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Bq/kg2 with an average of 23 Bq/kg. Assuming equilibrium between
uranium-238 and radium-226 this would imply uranium concentrations in
the range 0.3 – 4.5 mg/kg with an average of 1.9 mg/kg at the time the soil
sampling was undertaken. The uranium concentrations reported in the
more recent New Zealand studies on uranium accumulation in soils are
within the above range (R. MCDowell 2012, L. Schipper et al. 2011, M
Taylor 2007) and consistent with evidence by Dr Bull.
Radioactivity in Chatham Rise phosphate rock
30. Uranium content of Chatham Rise phosphorite has been discussed in
detail in Dr Bull’s evidence. Based on his analysis, a uranium content of
155 mg/kg for Chatham Rise phosphorite has been used in this
evaluation.
31. In addition to uranium, the phosphorite and fertilisers based on this
material will contain uranium decay products which are also radioactive
and form a decay chain (Hermanspahn, 2014). Rocks formed more than
one million years ago tend to have these decay products in “secular
equilibrium” with uranium, e.g., their activity values are the same as for
uranium. However, these decay products are different elements and have
therefore different chemical and physical properties to uranium.
Depending on environmental conditions, the uranium decay chain may
therefore not be in equilibrium. For the purpose of this evaluation uranium
decay products are taken to be in secular equilibrium, which would be a
conservative assumption, as it represents the scenario with the highest
activity concentration and therefore greatest dose to humans and biota.
Rate of application of uranium to agricultural soils
32. In this assessment two different fertiliser application rates have been used.
An application rate of 40 kg P/ha/yr, which corresponds to an intensive
pastoral farming scenario and an application rate of 10 kgP/ha/yr which
corresponds to an extensive farming scenario (see evidence by
Dr Mackay). Using a fertiliser with uranium content of 141 mg/kg and
phosphorus content of 15 % would give a uranium application rate of 41 g
2 The unit for radioactivity is the Becquerel (Bq). One Becquerel corresponds to one nuclear
transformation per second. Concentration of radioactive isotopes is often given in Bq/kg instead of mg/kg. As an example, for uranium-238 1 mg/kg equals 12.4 Bq/kg.
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U/ha/yr for the intensive farming scenario and 17g U/ha/yr for the
extensive farming scenario with use of pure Chatham Rise fertiliser (see
evidence by Dr Bull).
Accumulation rate in soil
33. For soils with a pH of 5 - 6 uranium is expected to essentially remain
bound to soil particles (partition coefficient KD in the range 100 –
1,000,000) and past studies have observed accumulation of uranium in
agricultural soils within New Zealand (see evidence by Dr Bull).
34. Biological processes induce mixing within the top soil resulting in
redistribution of fertilisers throughout the top 7.5 cm (see evidence by
DrMackay). Dose modelling uses homogeneous distribution of fertiliser
within the top 7.5 cm of soil as the starting point. This is a reasonable
assumption in view of the model running time of 5000 years.
35. Assuming a soil density of 0.8 g/cm3, and application rates as discussed
above and 100% uranium retention would then correspond to an
accumulation rate for uranium of 0.13 mg/kg/yr for the high application
scenario and of 0.03 mg/kg/y for the low application scenario.
36. These application rates are within the range of application rates given in
my report annexed to the Crown's submission but would exclude the
higher limit given therein. Differences are due to improved values for
uranium content in fertiliser.
Dose modelling
37. Doses3 to human population were calculated with United States’ Argonne
National Laboratory’s RESRAD 7.0 modelling software - see the document
annexed as Appendix B. RESRAD models the fate of radioactive
contamination based on environmental parameters and the resulting dose
to population from external radiation, inhalation, ingestion of drinking water
and transfer to food and subsequent ingestion by humans. For assessing
dose, the most conservative scenario of a subsistence farmer living on site
was used. This assumes that the population spends 100% of their time on
3 Dose in this instance is meant to mean total effective dose equivalent.
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the land and sources 100% of their water and food locally. Farm animals
only consume locally grown fodder. Doses to different age groups (1 year,
10 years and adult) were evaluated.
38. Dose conversion factors are based on the US EPA’s Dose Coefficient
Data File Package4.
39. Dose and risk are based on radiological impact only and do not include
chemical toxicity.
40. Some of the parameters used in the model are listed below:
Fertiliser application area of 100,000 m2.
Contamination of topsoil to a depth of 1cm or 7.5 cm.
Uranium and all decay products5 are included in model.
Erosion rate is set to 0, this is a conservative assumption indicating no
soil removal due to erosion.
Precipitation rate of 1400 mm/year and an irrigation rate of 600
mm/year were used.
The model includes movement of elements through soil, uptake by
plants and transfer into farm animals and humans.
The model does not include dose from handling fertilisers by workers
or farmers.
Dose is calculated for a resident population spending 100% of their
time on the contaminated land with a 50:50 indoor/outdoor split.
41. Partition coefficients6: based on a pH range for New Zealand soils of 5.5 –
6 a partition coefficient of KD = 10,000 was chosen for uranium. The strong
binding is consistent with the findings from uranium accumulation studies
(R. MCDowell 2012, L. Schipper et al. 2011, M Taylor 2007). For radium a
value of KD=2000 was chosen which would be expected for soils with
organic and clay content (IAEA 2014).
4 The data set is based on US EPA’s national guidance reports. For comparison one model run
was based on conversion factors published by the International Committee on Radilogical Protection (ICRP publication 72) and was found to be in good agreement. 5 Uranium-238 decay products are: thorium-234, protactinium-234, uranium-234, thorium-230,
radium-226, radon-222, polonium-218, lead-214, bismuth-214, polonium-214, lead-210, bismuth-210, polonium-210 and the stable isotope lead-206. 6 The partition coefficient describes how strongly the element is attached to the soil. Higher values
indicate stronger binding and therefore slower movement through the soil column.
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42. RESRAD cannot model continuous deposition of fertiliser. The starting
point (time zero) is defined by having a homogenous distribution of
uranium (all decay products in equilibrium) through the top 7.5 cm of soil
(or top 1 cm). Different periods of fertiliser application are assumed to
result only in different concentrations for uranium and its decay products
within this top layer. The model run was performed from time zero to a
time of 5000 years after deposition of the fertiliser.
43. Thickness of the unsaturated zone was set to 4 m. In the RESAD model
the thickness of this zone, rate of precipitation/irrigation and value of
partition coefficient define the time scale for radionuclides to reach
groundwater.
44. Default RESRAD food consumption parameters were used.
45. For determination of dose from radon, it was assumed that the building’s
concrete base sits level with ground surface. This is a more typical building
style in New Zealand as opposed to building practices overseas which
may include a cellar in the building design.
Results
46. Dose calculations were performed for age groups of 1 year olds, 10 year
olds and adults. Under identical conditions the age group of 1 year olds
would receive the highest dose. The difference is due to a higher dose
rate from ingestion.
47. The dominating pathways are radon inhalation, external gamma radiation
and ingestion of plants (see figure 6).
48. Radium-226 is the radionuclide with the highest contribution to dose with
dose pathways as described above (see figure 2).
49. Maximum dose rate occurs at T=0, eg at the start point for the model when
all radioactivity is defined to be in the top 7.5 cm of soil. Dose rates
decrease with time as the radioactive isotopes move down the soil column
which increases the shielding factor for external radiation and reduces the
radon emission rates. As radium-226 provides the largest contribution to
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dose its movement through the soil column has the largest influence on
how the dose changes with time (see figures 2, 3).
50. Maximum dose rate was not influenced significantly by varying the initial
depth from 1 cm to 7.5 cm while keeping total amount of uranium
constant. This shows that the model is robust against the starting
conditions. In reality fertilisers will be applied over a period of decades and
the radionuclides contained within the fertiliser will not assume a
completely homogeneous distribution within the soil layer. For calculation
of radiation dose, however, the model of a homogeneous distribution at
T=0 is adequate.
51. The following dose rates are based on the assumption that the total
amount of uranium and all its decay products for a given time period is
deposited homogenously within the top 7.5 cm of soil. Dose rates are
additional to existing natural background. In New Zealand this average
background dose to an adult is 2.2 mSv/yr.
Extensive Farming Scenario
Max Dose rates in mSv/yr
Fertiliser application
at 10 kgP/ha/yr
1 year old 10 year old Adult
1 year 0.0014 0.0011 0.0009
50 years 0.071 0.054 0.045
100 years 0.14 0.11 0.09
Intensive Farming Scenario
Max Dose rates in mSv/yr
Fertiliser application
at 40 kgP/ha/yr
1 year old 10 year old Adult
1 year 0.0034 0.0026 0.0022
50 years 0.17 0.13 0.11
100 years 0.34 0.26 0.22
52. Dose rates for application periods of 50 and 100 years do not take into
account redistribution of radium. For a radium partition factor of KD = 2000
the radium concentration of the top 7.5 cm will decrease over this time
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frame sufficiently to influence dose (Figure 3). As the modelling shows, the
highest doses are due to radium contained within the top layer, the
approach followed in this study will therefore result in a conservative
estimation of dose.
53. Dose to general public would be restricted to dose from ingestion. These
are about 50 % of the total dose rate for the 1 year old age group, 25 % of
total dose for 10 year old age group and 10 % for adults.
Assessment
54. Use of fertiliser wholly based on Chatham Rise phosphorites would result
in an additional radiation dose to members of the public. The group with
the largest risk factor is one year olds living permanently on the converted
farmland on a diet sourced completely from the site.
55. To assess acceptability of these additional doses they need to be
compared to regulatory dose constraints. The New Zealand Radiation
Protection Regulations do not apply to use of Chatham Rise phosphorites
as fertiliser as the material is not classified as radioactive material.
Therefore the ICRP guideline value for protection of public of 1 mSv/yr has
been used to calculate a derived soil guideline level. The soil guideline
level gives the uranium concentration at which there is the potential that a
person may receive a dose of 1 mSv/yr.
Derived Soil Guideline Level
Dose constraint 1mSv/yr
Uranium Soil GV 20 mg/kg
56. If a guideline level for uranium in soil of 20 mg/kg would be adopted it
would take 275 years in the high application scenario and 675 years in the
low application scenario to reach this limit.
57. Important environmental parameters, in particular partition coefficients and
soil to plant transfer factors are not well known for New Zealand
conditions. Improved values for these parameters would result in improved
accuracy of the dose calculations.
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58. Further refinement of the dose calculations could be achieved by adjusting
more parameters such as soil parameters, partition factors, rainfall,
irrigation, food intake etc. to New Zealand conditions. In addition,
probability functions instead of fixed parameters could be used for the
most critical input parameters to better estimate risk associated with the
use of marine phosphorites as fertiliser.
CONCLUSIONS
59. Marine mining of Chatham rise phosphorites will pose negligible
radiological risk to marine biota.
60. Uranium is expected to accumulate in agricultural soils, but radiological
impact will be within acceptable dose limit of 1 mSv/yr for all members of
public for more than 250 years of intensive fertiliser application.
61. The time frame will offer opportunities to improve understanding of
environmental fate of naturally occurring radioactive material and re-
evaluation of guideline levels.
Nikolaus Hermanspahn
29 August 2014
SCHEDULE OF APPENDICES
Appendix A: ERICA assessment report
Appendix B: Information on RESRAD
Appendix C: Extract of a RESRAD report
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REFERENCES (cited in this evidence)
Dobbs J., & Matthews K.. (1976). A survey of naturally occuring radionuclide
concentrations in New Zealand soils. New Zealand Journal of Sciences, 243-247.
McDowell, R. (2012). The rate of accumulation of cadmium and uranium in a long-term
grazed pasture: implications for soil quality. New Zealand Journal of Agricultural
Research, 133-146
Gascoyne M., (1992). Geochemistry of the actinides and their daughters, In R. H.
M.Ivanovich, Uranium-Series Disequilibrium
Hermanspahn N (2014). Uranium in Chatham Rise Phosphate Rock, ESR report
FW14021
ICRP (2007), The 2007 Recommendations of the International Commission on
Radiological Protection, ICRP publication 103
International Atomic Energy Agency (IAEA) (1988), Inventories of selected
radionuclides in the oceans.
International Atomic Energy Agency (IAEA) (2014), The Environmental Behaviour of
Radium: Revised Edition.
Schipper L., e. a. (2011). rates of accumulation of cadmium and uranium in a New
Zealand hill farm soil as a result of long-term use of phosphate fertiliser. Agriculture,
Ecosystems and Environment, 95-101.
Taylor, M. (2007). Accumulation of uranium in soils from impurities in phosphate
fertilisers. Landbauforschung Volkerode 2, 133-139.
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FIGURES
Figure 1: Risk factors for marine biota calculated by Erica Tool.
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Figure 2: Dose to resident adult with components from different radionucldes. Concentration for uranium-238, radium-226 etc. was 0.25 Bq/g. Radium-226 can be identified as the largest contributor to dose.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 1.0 10.0 100.0 1000.0 10000.0
Years
Pb -2 1 0 Ra -2 2 6 Th -2 3 0 U-2 3 4 U-2 3 8 To ta l
C:\RESRAD_FAMILY\RESRAD\7.0\USERFILES\UFERT25.RAD 08/18/2014 13:55 GRAPHICS.ASC Inc ludes Al l Pathway s
DOSE: All Nuclides Summed, All Pathways Summed
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Figure 3: radium-226 concentration in topsoil (7.5cm). Rate of movement of radium through soil is determined by the partition factor.
0.00
0.05
0.10
0.15
0.20
0.25
0.1 1.0 10.0 100.0 1000.0 10000.0
Years
C:\RESRAD_FAMILY\RESRAD\7.0\USERFILES\UFERT25.RAD 08/18/2014 13:55 GRAPHICS.ASC
CONCENTRATION: Ra-226, Contaminated Zone Soil
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Figure 4: Concentration of radium-226 in leafy vegetable. The concentration is given by the transfer factor soil - vegetable and the concentration of radium-226 in soil. The decrease in time is correlated with the decrease of concentration in topsoil.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.1 1.0 10.0 100.0 1000.0 10000.0
Years
C:\RESRAD_FAMILY\RESRAD\7.0\USERFILES\UFERT25.RAD 08/18/2014 13:55 GRAPHICS.ASC
CONCENTRATION: Ra-226, Leafy Vegetables
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Figure 5: Concentration of radium-226 in milk. Transfer is achieved through direct ingestion of soil and through fodder. Annual ingestion of 200L of milk at a concentration of 0.11 Bq/L of radium-226 would result in a committed dose of 0.006 mSv/year.
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.11
0.1 1.0 10.0 100.0 1000.0 10000.0
Years
C:\RESRAD_FAMILY\RESRAD\7.0\USERFILES\UFERT25.RAD 08/18/2014 13:55 GRAPHICS.ASC
CONCENTRATION: Ra-226, Milk
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Appendix A: ERICA assessment report
ERICA Assessment Report
26/08/2014
Project: u seawater
Assessment name: uranium in seawater
Author: N Hermanspahn
Purpose of the assessment
Assess impact of dissolved uranium during mining of marine phosphate rock.
Performed tiers
Tier 1
Tier 1
Stakeholder Involvement
Problem Formulation
Assessment Context
Inputs
Parameters
Outputs
Decision
Back to beginning of report
Tier 1 - Stakeholder Involvement
This is an intial assessment for the purpose of a resource consent application to the EPA.
Back to beginning of report
Tier 1 - Problem Formulation
Description
Mining of Chatham Riase phosphorite will results in disturbance of seafloor. The
process will result in dissolution of a fraction of the uranium. According to report by
Golder Associates the uranium concentration in near field plume will be 0.17 mg / m3.
Pathways and endpoints
Assessment of increased uranium decay chain nuclide concentration in seawater only.
The increased concentration within the plume is sufficiently low that the concentration
will quickly be diluted to be indistinguishable from natural uranium concentration.
Initial Tier1 assessment with standard ERICA reference biota.
Back to beginning of report
Tier 1 - Assessment Context
Ecosystem Marine
Transport
model None
Isotopes
Pb-210
Po-210
Ra-226
U-234
U-238
Back to beginning of report
Tier 1 - Inputs
Activity Concentration in water [ Bq L-1 ]
Isotope Value
Pb-210 2.10E-3
Po-210 2.10E-3
Ra-226 2.10E-3
U-234 2.10E-3
U-238 2.10E-3
Activity Concentration in sediment [ Bq kg-1 d.w. ]
Isotope Value
Pb-210 -
Po-210 -
Ra-226 -
U-234 -
U-238 -
Back to beginning of report
Tier 1 - Parameters
Marine Environmental Media Concentration Limit for Water (ERICA) [ Bq L-1
f.w. ]
Isotope Value
Pb-210 5.85E-2
Po-210 1.45E-3
Ra-226 2.43E-2
U-234 2.15E-1
U-238 2.51E-1
Marine Environmental Media Concentration Limit for Sediment (ERICA) [ Bq
kg-1 d.w. ]
Isotope Value
Pb-210 1.24E3
Po-210 4.46E3
Ra-226 7.19E0
U-234 1.90E1
U-238 2.22E1
Back to beginning of report
Tier 1 - Outputs
Risk Quotient [ unitless ]
Isotope Value Limiting Reference Organism
Pb-210 3.59E-2 Phytoplankton
Po-210 1.44E0 Zooplankton
Ra-226 8.63E-2 Sea anemones or true corals - colony
U-234 9.76E-3 Sea anemones or true corals - polyp
U-238 8.36E-3 Sea anemones or true corals - polyp
Sum of Risk Quotients [ unitless ]
Value
1.59E0
Back to beginning of report
Tier 1 - Decision
Justification for the decision
Risk quotient for uranium is less than 0.02, eg risk from dissolved uranium is
insignificant.
Largest risk quotient was found for Po-210. It exceeded 1 at 1.4 for zooplankton, eg a
dose of 14 uGy/hour for zooplankton.
This is deemed to be not significant for introduction of remedial measures.
Elevated concentration of naturally occurring radioisotopes will be diluted rapidly with
distance from the active mining activity and will only be temporary of nature as the
mining site will continually shift.
END OF REPORT
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Appendix B: Information on RESRAD
RESRAD
RESRAD is a computer model that was developed by the US Argonne National Laboratory. It is
designed to estimate radiation doses and risks from RESidual RADioactive material. It is used as a
tool to determine risk minimisation measures for contaminated sites by determining how
radionuclide concentrations in soil, water, air and biota change with time and how this affects dose
to a resident human population. The model was developed for contaminated sites but the scenario
of naturally occurring radioactivity in fertiliser is well within the bounds of the model.
RESRAD takes into account all significant exposure pathways
Direct exposure to external radiation from the radioactivity in the soil.
Internal dose from airborne radionuclides including radon.
Internal dose from ingestion of plants which may take up radioactivity through their roots
from soil or from irrigation water
Internal dose from meat and milk from animals which have been fed contaminated fodder
and water
Internal dose from drinking water
Internal dose from ingestion of freshwater fish
Internal dose from direct ingestion of soil
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Appendix C: Extract of a RESRAD report