DENITZA VOUTCHKOVA PHD FELLOW AARHUS UNIVERSITET 22. AUGUST 2012 Multivariate Analysis of Danish Historical Hydrogeochemical Data with Respect to Iodine in Groundwater AU SESEH 2012 Sino-European Symposium on Environment and Health (SESEH 2012) Galway, Ireland, August , 2012

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 WHO ARE WE? › Danish project, financed by Geological Survey of Denmark and Greenland (GEUS) and Aarhus University ( ): “Iodine in the hydrological cycle in Denmark: implications for human health“ 2 Søren Munch Kristiansen Birgitte Hansen Kim Esbensen Vibeke Ernstsen Brian Sørensen summary results datapurpose iodine in dk

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 IODINE IN DENMARK 3 Europe Denmark › Mild iodine deficiency based on median UI = 50-99ug/l (WHO, 2007) subnational survey data: 2 cohorts › Mandatory › Mandatory fortification since 2000 (13mg/kg) › ~25% drinking water › ~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 0,7ug/l to 140ug/l › Iodine in drinking water in Denmark varies from 0,7ug/l to 140ug/l (Pedersen et al., 1999, Andersen et al., 2002) groundwater origin › Danish drinking water is ~100% with groundwater origin summary results datapurpose iodine in dk

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 PURPOSE OF THE STUDY is not studied Iodine in Denmark is not studied from geochemical point of view We want to: map and explain the spatial variations; understand the involved processes; find the source(s) of iodine in the groundwater in Denmark; HOW? By MVD exploration of the different data we have and hydrogeochemical interpretation of the results summary results datapurpose iodine in dk limestone gwt dry and wet I deposition volatilisation uptake topsoil iodine cycle in the ocean leaching org. I inorg. I reduction Sea water intrusion Upward transport of old saline water diffusion bioaccumulation decomposition aquitard sorption desorption aquifer Marine deposits Conceptual model of iodine cycle in Denmark

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST chemical variables 26 chemical variables: I, Li, H 2 S, CH 4, O 2, Agg. CO 2, NVOC, PO 4, SO 4, NO 3, K, Fe, Mn, HCO 3, Ca, Mg, Na, Cl, Fl, B, Ba, Br, Sr, conductivity, redox, pH; Geology Geology at the well screen; Lab methods Calculated in ArcMap: Distance to the coastline Distance to the coastline Distance to major geological faults Distance to major geological faults AVAILABLE GROUNDWATER DATA JUPITER JUPITER is the Danish nationwide database of groundwater and drinking water ( summary results datapurpose iodine in dk

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 IODINE DATA 6 Number of Iodine samples Status December 2011: 2562 samples summary results datapurpose iodine in dk Iodine in groundwater (n=2562) for the period

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 DATA PREPARATION FOR MVDA cleaning › Dataset cleaning (excluded all additional information coming from Jupiter) quality › Data quality assessment › Iodine data inhomogeneity due to analytical method › Values below detection limit › Errors reduction › Dataset reduction › Reduction of variables › Reduction of samples 7 28 variables 2562 samples Lots of missing values 28 variables 2562 samples Lots of missing values 20 variables 505 samples Few missing values 20 variables 505 samples Few missing values summary results datapurpose iodine in dk

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 MVDA STRATEGY 8 1 st group 2 nd group 3 rd group a b c 7PC 7PC needed to explain 75% 75% variance structure noise summary results datapurpose iodine in dk Principal Component Analysis We found 3 groups of samples showing multivariate structure on the first 3 PCs and analysed them further

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 PLS-R MODEL 9 P artial L east S quares R egression Model R²=0,76 (3 PCs, 75% of the variance) Slope 0,77 3PC 3PC needed To explain 75% 75% of the variance validation calibration 1:1 noise data summary results datapurpose iodine in dk

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST RESULTS AND INTERPRETATION Iodine Ba HCO 3 Br Na Fe SO 4 Ca K Cl cond. B Sr Li NO 3 Mn pH faults coast Mg Sønderborg Jammerbugt Ishøj Gladsaxe København Lejre Frederiksberg Loading Weights plot Score plot Interpretation based on the Loading Weights plot and Score plot (PC1-PC2) summary results datapurpose iodine in dk Other factors (location and water quality): geology, screen depth, municipality, Na/Cl ratio, Cl/Br ratio, Redox, SI

AARHUS UNIVERSITET SESEH 2012 DENITZA VOUTCHKOVA 22. AUGUST 2012 SUMMARY › It is possible to study › It is possible to study the groundwater origin and the processes governing the water composition by MVDA; › Important factors › Important factors for the Iodine variation, based on the PLS-R model : › Future: › Future: smaller scale studies focus on the geochemistry; groundwater/drinking water; connection to the human health; 11 summary results datapurpose iodine in dk