denitza voutchkova phd fellow aarhus universitet 19. june 2012 iodine in groundwater in denmark...

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

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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

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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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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

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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)

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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

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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?

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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%

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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

1

Data preparation

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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)

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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

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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:

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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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denitza voutchkova phd fellow aarhus universitet 19. june 2012 iodine in groundwater in denmark...

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