1. METREAU part II
Analysis Division
March 10, 2003 1

2. METREAU
Objectives
To estimate the uncertainty related to the sampling of groundwater
To evaluate the variability in space-time of groundwater chemical composition at the scale of an industrial site
To assess the true quality of groundwaters
To understand the behaviour of pollutants in groundwater
To elaborate appropriate protocols for groundwater sampling
> 2 3

3. METREAU Site Characteristics In the « BIC 2 » borehole
Potash production
site in France
Site Characteristics
Groundwater subjected to a specific pollution of heavy metals
3 boreholes located close together
In the « BIC 2 » borehole
1996 data:
[ Pb ] = 206 µg/l; [ Cd ] = 28,9 µg/l
2002 data:
[ Pb ] = 1 µg/l; [ Cd ] = µg/l
BIC 2
BIC 3
300 m
Aval hydraulique
BIC 1 3

4. METREAU Uncertainty estimate related to the sampling stage
Estimate by field testings of groundwater sampling repeatability and reproducibility
Definition of a specific protocol
1/ On site measurements of chemical and physical parameters versus depth in BIC 2
2/ Sampling at 3 different levels, with 10 samples per level
3/ Specific sampler using gas pressure system
4/ Chemical analysis of major and trace elements by ICP/MS: 26 chemical elements
5/ Statistical data processing 3

5. METREAU
Logs of chemical parameters C T O2 Eh pH
Example for BIC 1 3

6. Uncertainty related to the sampling stage
METREAU
Uncertainty related to
the sampling stage
Analyse et Caractérisation Minérale 3

7. Uncertainty related to the sampling stage
In the BIC 2 borehole :
No particular layering /stratification of water
3 levels selected, 10 samples collected per level
3 analysis of lead contents in each sample
Calculation of the uncertainty related to the sampling step A B C O2 pH Eh T C
BIC 2 3

8. Uncertainty related to the sampling stage
lead contents and statistical processing (ANOVA method)
[ Pb]A = 0,94 ± 0,16 (18%); n=10 samples
[ Pb]B = 1,20 ± 0,33 (28%); n=10 samples
[ Pb]C = 0,51 ± 0,12 (24%); n=10 samples
Uncertainty related to the sampling stage
about 20% for a content of 1 µg/l
results in total agreement with analytical uncertainties (close to 3% ; Icp-ms method) 3

9. Uncertainty related to the sampling stage
If we suppose a random sampling in this borehole and then one analysis in lab
Estimate of uncertainty based on 30 samples:
good estimate of the true value and small uncertainty
if not: statistical calculation allows estimation of an unknown value
[Pb] content shoul be close to the mean value: 0,88 µg/l
Uncertainty will be close to 0,82 µg/l (  100%) 3

10. Space-time variability of groundwaters
METREAU
Space-time variability of groundwaters 3

11. Space-time variability of groundwaters
Definition of a specific protocol
measurements of chemical parameters logs in each borehole
sampling in each layer of each borehole
Renewal of field tests repeated over 2 days
analysis of major and trace elements: 26 chemical elements
About 1400 values available:
principal component analysis (PCA)
Results PCA:
only 4 parameters needed to explain 90% of the variability of data variation 3

12. Space-time variability of groundwaters
BIC 1
BIC 3
BIC 2
Spatial variability of
chemical parameters
between boreholes 3

13. Space-time variability of groundwaters
BIC 1
level A
BIC 1
level. B,C
BIC 2
BIC 3
Spatial variability : two factors
chemical composition between borehole and depth 3

14. Space-time variability of groundwaters
Results of data processing by PCA
Identification of the 4 main effects responsible for spread in data:
Analytical effect: sampling + analysis
space effect identified between each borehole
depth effect identified into two boreholes
time effect between D and (D+1) and between July and October samplings
Origin of time variation? 3

15. Time variation Field observation into BIC 2 sample:
orange suspended matter containing
living micro-organisms 3

16. Time variation
SEM
10000 X
SEM
3300 X
FeS: pyrite nodules
Bacteria 3

17. Time varition is related to bacterial activity
Time variation
Results of chemical analysis:
organic and suspended matter water sample: BIC 2
[Al]  ppb  1 ppb
[Fe]  ppb  200 ppb
[Pb]  140 ppb  0,4 ppb
[As]  1200 ppb  13 ppb
[Zn]  37 ppb  8 ppb
Time varition is related to bacterial activity 3

18. METREAU Conclusions Uncertainty related to the sampling step:
Lead content: about 20% for a concentration level close to regulatory limits
Uncertainty related to the analytical step:
Lead content : about 3% in the case of METREAU
Uncertainty of a random sampling on one borehole:
Lead content : about 100%
Space-time variability on this site
strong variability between 3 boreholes located close together 3

19. Proposal (1)
The understanding of natural variations needs specific field protocols for accurate data acquisition
Proper assessment of the uncertainty of measurement requires procedures taking into account uncertainty on analysis and on sampling
Harmonized validated protocols must be defined at the European level for the sampling of groundwaters to ensure data quality and consistency 3

20. Proposal (2)
Monitoring programmes for implementation of Water Framework Directive need:
measurement techniques of demonstrated quality for assessement of water status and to control pollution pressures endangering water status
to compare existing rapid techniques and to check their validity
to develop innovative « low cost » screening methods 3