in the matter...the assessment. risk factors as determined by erica tool were in the range 0.008 –...

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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


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


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.


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.


Tier 1 - Assessment Context

Ecosystem Marine

Transport

model None

Isotopes

Pb-210

Po-210

Ra-226

U-234

U-238


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 -


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


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


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

25114649

Appendix C: Extract of a RESRAD report

in the matter...the assessment. risk factors as determined by erica tool were in the range 0.008 –...

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