DENITZA VOUTCHKOVAPHD FELLOW
AARHUSUNIVERSITET
19. JUNE 2012
IODINE IN GROUNDWATER IN
DENMARKIMPLICATIONS FOR HUMAN HEALTH
AUATV Jord ogGrundvand
Naturligt forekommende stoffer i jord eller grundvand og deres sundhedseffekter
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
PROJECT PRESENTATION› Geo-Center project, financed by GEUS and AU (2011- 2014)
› Project title: “Iodine in the hydrological cycle in Denmark: implications for human health“
› Objective: to combine both the medical and the geochemical aspect by studying the variations in iodine bioavailability in groundwater and to evaluate the human health effects.
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Søren Munch Kristiansen Birgitte HansenKim Esbensen
Vibeke ErnstsenBrian Sørensen
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
PRESENTATION OUTLINE
› Iodine – essential trace element
› Iodine in Denmark
› Geochemical aspect
› Present work›Data ›Method description›Workflow overview ›Some results›Conclusions
›Future plans and perspectives
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AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
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IODINE – ESSENTIAL TRACE ELEMENT
toxicity
defi
ciency
intake
funct
ion
Dose-response of essential trace
elementsSafe and adequate
intake
RNI UL
group RNI ug/day(WHO)
UL ug/day(European
commision)
UL ug/day(IOM, US)
0-5yeras 90 200-250 200-300
6-12years 120 250-450 300
12-17 years
150 450-500 300-900
adults 150 600 (500)* 1100
pregnant 200 600 1100
* Expert committee on Human Nutrition, France
regulates the metabolic processes in cells; plays role in the early development of most organs
Recommended daily nutrient intake
The highest average daily nutrient intake level unlikelyto pose risk of adverse health effects
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
IODINE IN DENMARK
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Mild iodine deficiency based on median UI = 50-99ug/l (WHO, 2007)
Subnational survey data (2 cohorts - Aalborg and Copenhagen; west Denmark – moderate; east – mild)
1998 2000
Voluntary fortification of table salt aiming increase with 50ug/day
Pro
gra
m fa
iled
Mandatory fortification (13mg/kg) of household salt and the salt used for commercial bread production
DanThyr
~25% of iodine intake in the Danish diet is derived from drinking water, coffee, tea and other beverages (Rasmussen et al., 2000)
Iodine in drinking water in Denmark varies from 0,7ug/l to 140ug/l (Pedersen et al., 1999, Andersen et al., 2002)
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
GEOCHEMICAL ASPECT
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Iodine in groundwater – not studies from geochemical point of view• Mapping Regional (and/or temporal) variations• Understanding the involved processes• Finding the source/sources of iodine in the groundwater in
Denmark
Available historical data:• From groundwater monitoring programs (mainly GRUMO wells);• Iodine is not part of the waterworks monitoring;
Iodine speciation – important for the geochemical understanding of the Iodine cycle
𝐼𝑂3❑−
Organo-iodine Inorganic iodine Total iodine
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
PRESENT WORKMultivariate data analysis of historical Danish groundwater data
› Purpose: to elucidate the iodine source(s) in the sediments, the governing processes of its distribution and variations
› Method: exploring correlations between the different data by using PCA and PLS-R
› Hypotheses testing: Iodine enrichment:
› is originating from marine deposits and infiltrating seawater nearby the present coastline;
› is due to desorption of iodine from old Cretaceous marine deposits;
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Other constituents
GeologyDistance to coastline
Distance to major faults
I
Is there a correlation?What kind (+/-)?
Why?
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
IODINE IN GROUNDWATER
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Number of Iodine* samples0 200 400 600 800 1000
1933
19401941
19581959
1975
19861988 1990
1991
1995
2001
20052006
2011Status December 2011: 2562 samples
Iodine in groundwater (n=2562) for the period 1933-2011
Iodine concentrations:ug/l
ug/l
ug/lug/l
ug/l
ICP-MS42%
SM20%
FIA7%
IC3%
ICP3%
S1%
Unknown24%
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
WORKFLOW OVERVIEW
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SRJODCLBRBA
BORFL
NAMGCABIKMNFEK
REDLEDPH
NO3SO4PO4
NVOCAGGCO2
O2CH4H2S
LI
1269
2562
1628
1247
1406
2131
875
987
1048
1026
1059
1617
1623
1614
822
1686
1693
1627
1621
237
901
667
65
417
430
1200
RM
S
20 variables505 objects(some missing values)
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Data
preparation:
1. Variables
exclusion
2. Detection limit
handling
3. Gross outliers
check
4. Objects
exclusion
Reduced Master Set, prepared for MVDA
Background population453 objects
PCA4b
Multivariate
analysis
RM
S
3 clusters +Background population
4a PCA
PLS3 clusters52 objects
4c
5Interpretation of the MVDA
Mast
er
set
28 variables:IodineLi, H2S, CH4, O2,Agg. CO2, NVOC, PO4, SO4, NO3, pH, K, Fe, Mn, HCO3
, Ca, 2562 objects(many missing values)
2Mg, Na, Cl, Fl, B, Ba, Br, Srconduct. redox,distance to coastline,distance to major faults
Jupit
er
raw
data
Extraction ofdata from the JUPITER----
DGU numberSample numberScreen numberScreen depthX, Ylab methodsdateGeology26 chemical variables
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Data preparation
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
PLS-R MODEL
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Background population453 objects
PCA4b
RM
S
3 clusters +Background population
4a PCA
PLS
3 clusters52 objects
4c
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Interpretation of the MVDA
Calibration Validation
Factors
Factor-0 Factor-1 Factor-2 Factor-3 Factor-4 Factor-5 Factor-6 Factor-7 Factor-8 Factor-9
Y-v
aria
nce
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1Residual Variance
Partial Least Squares Regression ModelR²=0,76 (3 PCs, >70% of the variance)
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
RESULTS AND INTERPRETATION
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Loading
weights plot
SP: Aquifer type
SP: Screen depth
Sp: Municip
ality
Sp: Na/Cl ratio
SP: Cl/Br ratio
Sp: Redox type
Location
Water type
Interpretation based on the Loading Weights plot and Score plot (PC1-PC2)
Factor-1 (34%, 48%)
-0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5
Fac
tor-
2 (1
1%,
31%
)
-0,4
-0,3
-0,2
-0,1
0
0,1
0,2
0,3
0,4
0,5
X-loading Weights and Y-loadings
DIST_FAULT
DIST_COAST
SR2126
CL1591
BR1542
BA1516
BOR1536 NA2096
MG2081
CA1551
BIK305
MN2086
FE204X
K2056
LED0011
PHX
NO3X
SO4_2142
LI2076
JOD2051Iodine Ba
HCO3
Br Na
Fe
SO4Ca
K Cl
cond.
B Sr
Li
NO3
Mn
pHfaults
coast
Mg
Sønderborg
Jammerbugt
Ishøj
Gladsaxe
København
Lejre
Frederiksberg
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
CONCLUSIONS
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• It is possible to study the groundwater origin and the processes governing its composition by combining MVDA and traditional hydrogeochemical tools,
• Data quality - important issue affecting the outcome of the analysis;
• It was not possible to build satisfactory model explaining iodine concentrations based on all samples and the 20 variables
• Variables important for explaining the variation in iodine concentration were found (and will be used in next studies)
• A new factor, not included in the working hypothesis was found: distance to major faults
Based on the PLS model (46 samples) it was not possible to reject the two hypotheses. • desorption from the sediment and • saline water are possible
contributors; • breakdown of organic might
contribute too.
Geochemical processes releasing Iodine to groundwater:
AARHUSUNIVERSITET
IODINE IN GROUNDWATER IN DENMARK
DENITZA VOUTCHKOVA19. JUNE 2012
FUTURE PLANS AND PERSPECTIVES3 small scale detailed studies
› Ishøj, Randers, Skagen
› designing a sampling and experimental campaign
› Hydrogeochemical aspect: sources and processes on a smaller scale
› Improved control over data quality
› Relation to existing epidemiological studies
National study on Iodine in drinking water› sampling from drinking water wells
› reflecting different geological regions, the waterworks size, and the administrative division of Denmark;
› speciation, water composition mapping and MVDA
› combined study with data from medical registers (spatial correlations with IDD occurrence, specific drug use, or other iodine related health issue)
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