The hydrogeochemistry of Norwegian bedrock ground- water - selected parameters (pH, F-, Rn, U, Th, B, Na, Ca) in samples from Vestfold and Hordaland, Norway

GEIRMO RLA N D ET ALIA NG U-B U LL43 2 , 19 9 7 - PAGE 103

The hydrogeochemistry of Norwegian bedrock ground- water - selected parameters (pH, F-, Rn, U, Th, B, Na, Ca) in samples from Vestfold and Hordaland, Norway

GEIR MORLAND,CLEMENSREIMANN, TERJE STRAND,HELGE SKARPHAGEN,DAVID BANKS,KJELL BJORVATN,GW ENDY E.M.HALL&ULRICH SIEWERS

Morland,G.,Reimann,C,St rand,1.,Skarphagen,H.,Banks,D.,Bjor vatn, K.,Hall,G.E.M. & Siewers,U.1997:Thehydro- geo chem istry ofNorweg ian bed rock groun dwa te r- selected param eters (pH,F-,Rn, U,Th,B,Na,Ca)insam plesfrom VestfoldandHordaland,Norway.Norges geologiskeunderssekelse Bulletin432,103-117.

Over300samplesof bedrock gro undwaterfromHordalandcountyandtheOslo rift lithologiesofVestfold county havebeencollecte dandanalysedforradonandfluoride.A selectio nof150 samples havebeen analysedforalarg e rang eofmajorand trace parametersbyICP-AES andICP-MS techn iq ues at tw odiffe rentlaborat ories.53%of allwa- ters cont ravenerecogniseddrinki ngwate r limit s foratleastoneof thefoll owin g param eters:pH,U,Rn,F-and Na.The majority ofthesecont ravent ions are identifiedin theHordaland area (64%cont ravention),wit ha rate ofonly28%

contravention in Vestf old.Maximumlevels of 2mg/L,6840 Bq/Land 9.2mg/Lwere record edforU,RnandF-,respec- tively.Thesefindin g shave implicationsforwater resourcepolicy ina countrywheregroundw aterisactive lybein g promot ed as analternative to vulnerablesurfacewate rsources.Bedrockgroundw ater may stillbe conside reda via- bleresourceprovid ed thateffo rtisinvestedincompilinghydrochem icalhazardmapsforbedr ock groundwaterand providedthatconsumersandwatersuppliers arewillingto accepttheneed foradegree ofwatertreatmentinsome cases.

GeirMorland,HelgeSkarphagen,Norgesgeologiskeundersokelse (GeologicalSurveyofNorway),P.o.Box534BMajorstua, N-0304 Oslo,Norway.

ClemensReimann,David Banks,Norgesgeologiskeundersekelse,P.O.Box 3006Lode,N-7002Trondheim,Norway.

TerjeStrand,StatensStralevern (Norwegian Radiati onProtection Authority),P.O.Box55,N-7345 0steras,Norway.

Kj ellBjorvatn,Institutt for odontologiskforskning (Institute for DentalResearch),University of Bergen,Arstadveien77,N- 5009Bergen,Norway.

GwendyE.M.Hall,Geological Surveyof Canada,607BoothStreet,Ottawa, Ontario,CanadaKl A OBE.

Ulrich Siewers, Bundesanstalt fur Geowissenschaft enund Rohstoffe (Federal Institutefor Geosciencesand Natural Resources),P.O.Box510753,D-30637Hannover,Germany.

Introduction

In Norw aymo rethan80%of the populationreceivesdrink- ing wate r from surface wate rsour ces (Ellingsen& Ban ks 1992).In the 1980s the Geolog ical Su rvey of No rw ay (NGU)undertook an exten siveinvest ig ation of the che m i- cal co m posi t ion of sur fa ce and groundwater samp les from almos t all Nor w egi an wate rworks sup plying mo re than 1000 peopl e wit h drin king wate r.Thisundertakin g resulted in dat a on the chemical compo sition ofwat er drunkby70%of theNo rwegi an populati o n formajor and so m etrace parame ters(Flate n 1991).Since thattim e, in- creasingl ysensit ive meth o d shavebecome available(e.g.

ind uc tive lycoup ledplasma massspe ct rometry-ICP-MS) fordet erm ini ngverylow levels oftrace elemen ts. Interest hasalsoincrea sedin thesignificanceofsome,previously seldomanalysed, param et ers in the contextof human he- althand also intheuse of surface andgroundw atersasa geochemical mapping med ium (e.g.the No rwe gian sur- veyof 473lakes; Skj el kvale etal.1996).

NGUand theNorweg ian Radi at ionProt ection Author- ity(NRPA)have invested sig nificanteffort in recent years in investigating concentra tio ns of radionuclides in

grou ndwaterabstracted from No rw ay'scrystalli ne bed - rock (St rand&Lind 1992,Banks etal.1995a,b).Thesest u- dieshaveconfi rme d thatasig nificant prop ort ion of bed- rock gro undwatersinso melit hol og ies (particu larly grani- tes and gneisses)exhibitradonconcentra tionsofseveral hundre d or even thousan d Bq/L . Such co ncentratio ns may have adirect health im pac t viainges t io noran indi- rectoneviadeg assin ginside ahou se andsubse q ue nt in- halatio n (Swedje m ark 1993).The inves tiga ti o ns resulted intheNRPA(1995) reco m me ndi ngan action level of500 Bq/L forRn indrinking water.

The work of Banks et al. (1995b) and Sceth er et al.

(1995) revealed that conce ntratio ns of other trace ele- ments suc hasF,Be,Th,U in bed ro ckmaybesig nificant in ahealth context.In fact,Bjorvatn etal.(1992,1994) have docume nte d cases of den t al fluorosis in sout hern and western Norway ascriba b le tothe consu m ptionof fluori- de-richbedrock groundw at er.

This paper presents selected resu lts from a recent, mor eextensivesurvey(Mo rlandetal.1995, Reimann etal.

1996)ofover 300 bed roc kbor eh ol esin theVestfold and Ho rdal an d areas,dom in at ed by grani t ic and gneissic lit -

NGU-BULL 432,1997 - PAGE 104

holo g ies.The studyuncovered significa nt levels of Rn(up to 6840 Bq/L)and U(up to 2 mg/L)in bedrock gro un d- waters.Reportsconcernin gpoor water qualit y have histori- cally always result edin acertain amountof media hysteria (Ibsen 1882)andthe situa tion issimilartoday.Unfortunately, some of the media reports have been misleading and may havedamaged publicconfidencein ground wate ras a drink- ing wat erresource. This paperattempts to discuss the re- sults objec t ively and to address the issue of whether ground wat er can continu e to be promot ed as the universal, problem-free panaceafor municipalities withexistingsurfa- ce water resources of unsatisfactoryquality.

Materia ls and meth ods

In 1994,groundwatersamplingof all known boreholesin bed rock in Hordalandcounty(ca.1,000boreholes)and in three munici palit iesinVestfo ld county(Vale,Svelvik and Holm estrand-314borehol es)was undertaken as a colla- boration betw eenthe health and envi ro nment authorit i- es of northern Vestfold and the Department of Dental Research,University of Bergen.The full result sof the fluo- ride analyses of thesewat ers have recently beenreported by Bardsenet al.(1996). By requestfrom NGU additional samples were taken from a selection (all 314 fro m the Vestf old area,58 fro m the Hordaland area)of the drilled wells for more detailed chemical analyses.These were subject to radon analysisat the NRPA and fluoride analy- sis at the Institutefor Dental Researchin Bergen.A selecti- on of 150of the samples was submittedfor ICP-MS ana- lysis of trace elements at the laboratories of the Geological Survey of Canada (GSC) and the Fed eral Instit ut e for Geosciences and Natura lResources (BGR) in Germ any.The full results of the study are reported in Morlandet al.(1995) and Reimannet al.(1996).

All samples were taken by staff of the local health aut- horit iesin the Vestfold area and bytheInsti tu te forDent al Research in the Hordaland area.Samples were collected fro m bo reholes whichwere in regular use(to ensure the collect ion of «fresh»groundwater).Immediately before samp ling,the tap (w hich may have been atthe well-head or indoors) was run for at least five minutes priorto the acquisit ion of 120 mL aliquots of sample.Temperature was monito red during sampling to ensure fresh ground- wat erwas being sampled .The samples were not filtered (o r acidified) in the field.This decision was consciou sly chosento meet the objectives of the project as awho le, i.e.to assess the total intake of the analysed elem ent s by people using the groundwateras drinkingwater. The fact that samples were not filteredmay,howe ve r,lead to pro b- lems in the hydrochemical inter pr etat ion of resul t s,as so me elements (e.g.Th and therare earths)are known to be strongly bound to particulate or colloidal matterin the water.Nodet ailed studiesof the effects of filtration were carried outduring thisinvestigation altho ugh such studi-

GEI R MO RLAN D ET ALIA

es are currently underway in a similarnational mapping of groundwater quality. Previous studies (Banks et al.

1995b) have indicate d that filt rat io n has lit tle effect on determined U and Th concentrationsand,by implicat ion , that most groundwaters sampled fromlong-established , regularlypumped boreholes arerelat ive lyfreeof part icu- lat es.

Analytica l methods

For sampling of radon,a plasticfunnelwasinserted below the runningwater tap,suchthat the tap mouth was under wat er and therewere no airbubblesin thefunnel. Using an adju stable autom at ic pipette, with disposab letips,a quant um of 10mLwat erwas taken fromthe funne land injected slow ly int o a 20 mLvial containing 10mL of pre- filledscintillatio n liq uid(Lum agel).The ampouleof scint il- lation liquidandwater was thensealed and shaken.The li- qui d gelsin contact with water,immobilisingthe radon.

Sampleswere deliveredto NRPAwithi n 3 days and analy- sed using an LKBWallac1215 scint illat ion co unt er,calibra- ted using a standard radi um solutio n.Results were correc - ted for rad ioact ivedecaytogive a rad o n concentrat ion in Bq/Lat the tim e of samp ling.

The pH of the 58 groundwaters from the Hordaland area and 123 ofthe gro undwa ters fromtheVestf old area was determined in thefield using a portablepH meter.

Afterw ards,a 30 mL sample was taken inapolyethyle- ne(PE)bottlefor fluoride determ ination at the local he- alth authorities and at the Institu t e of Denta l Research, Unive rsity of Bergen, using an ion- sensitive elect rode (Orio n 960900 combinedFelectrode).

Fin ally,twonew PE bott les(120 mL) werethoro ug hly rinsed three times with running tapwat erand then filled to the top.At NGU the fin al select io n of 150 samples for ICP-MS analysiswas made.The samp les were sent by cou- rier tothe Geo lo g icalSurv ey of Canad a's(GSC)labor at ory

Element

D .L.

Element

D .L.

Element

D. L.

Ag 0.05 AI 2 Ba 0.2

Be 0.005 Cd 0.05 Ce 0.01

Co 0.02 Cr 0.1 Cs 0.01

Cu 0.1 Dy 0.005 Er 0.005

Eu 0.005 Fe 5 Gd 0.005

Ho 0.005 In 0.01 La 0.01

Li 0.005 Lu 0.005 Mn 0.1

Mo 0.05 Nd 0.005 Ni 0.1

Pb 0.1 Pr 0.005 Rb 0.05

Sb 0.01 Sm 0.005 Sr 0.5

Tb 0.005 TI 0.005 Tm 0.005

U 0.005 V 0.1 Y 0.01

Yb 0.005 Zn 0.5

Tabl e 1.Elements analysedby ICP-MSat GSCwith detection limits in

~g/L(D.L.).

GEIRMORLAND ET ALIA NGU-BULL 432,19 9 7- PAGE 105

yp Litholo- Num- Number Rocks

gical ber ofICP-

class of MS

wells analyses

Basa_O 18 4 Permian basalts

Gran

°

^{44 10} Drammen Granite

Laba_O 10 1 Permianlatit esand basalts

LacO 227 67 Permian

latites/rhomb porphyry lavas Other_O 15 10 Basic igneous rocks,

trachyte, syenite, metasandstone

Lithological Number Rocks class of wells

Gran_B 7 Graniteand/or

granodiorite

Metse_B 4 Metasedim ents including phyllite andrneta-arkose Miam_B 7 Migmatiticgneisses with

amphibolitesand metagabbros

Migm_B 7 Migmatites

Mign_B 23 Migmatiticgranitic or granodior iticgneisses Other_B 10 Miscellaneous rock t es AI,Fe,Cr and Ni (see Reimannet al.1996for further de- tails).Rare earth element hyd rochemist ry isdiscussed by Bankset al.(in prep.).

Data analysis

All graphics are produced using the DAS program (Dut te r et al. 1992),based on exploratory data analysis (EDA) methods (Tukey 1977 and Velleman and Hoaglin 1981).

KOrzl (1988), Reimann et al. (198 8), Rock (1988) and O'Conno rand Reimann (1993)give an introduction to the advantages of using exploratory data analysis methods when dealing with geochemicaldata.

Analyt ical results were classified on the basis of the aquifer geologyat the boreho le locat io n into oneof11 maincategories (Tables3and 4).During stat ist ical treat- ment,anydata below the detec tion lim it s ofthe tech ni- que wereset to half the detectio n limit .

Table3.ThefivemainIithol ogi calclassescontain ing sampled bedr ock wells in the Vestfoldarea.

where the sample bott les were opened for the first time since sampling, acidified withult rapure nitricacid(at the rate of1mL per 100mL sample)and shakenfor 24hours.

They were then analysedby ICP-MS (VG PlasmaQuad 2+ ) for the elementslisted in Table 1.

Details of the analytical methodology, wit h associated figure of merit (t ypical accuracy and precision ),can be found in Hall etal.(1996).In addition (det ect io n limits in brackets)Ca(0.2 mg/L),K(0.1 rnq/L),Mg (0.2mg/L)and Na(1mg/L )were analysed by ICP-AES.lnternationalstan- dard s as well as GSC-in-house standards and sample blankswere run for quality controlpurposes. Aliquots of 20 samples (17 samp les and 3 standards) were then shi pped to BGR'sICP-MS lab orato ryfor analysis.Samples wereshippe dbacktoNGUandstoredina refrigerator.

Several months lat er, when theresults of the init ialin- terlabo ratory compa rison and the fir st results from the whole data-set were available,BGR became interes te d in analysingthewho leset of1SOsamp les.Theoriginalsam- plesthat had been in Canada and then stored refrigera- ted atNGUfor abou t 6months were the nshipped to BGR and analysed by ICP-MS (SCIEX ELAN 5000) wit hi n tw o weeks after arrival for the elements listed inTable2.

Results ofint erlaborat o ry comparison and storage ef- fects on water chemistry are reported in Morland et al.

(1995) and will be published separately (Hall et al. in prep).Generally,the results obtained from the two labora- toriesare in excellent agreement, with the exception of

Element

D .L.

Element

D .L.

Element

D .L.

Ag 0.001 AI 0.05 As 0.025

B 0.01 Ba 0.002 Be 0.002

Bi 0.001 Br 0.1 Ca 10

Cd 0.002 Ce 0.001 Co 0.005

Cr 0.01 Cs 0.001 Cu 0.005

Dy 0.001 Er 0.001 Eu 0.001

Fe 2 Ga 0.001 Gd 0.001

Hf 0.002 Hg 0.005 Ho 0.001

In 0.001 K 10 La 0.001

Li 0.002 Lu 0.001 Mg 10

Mn 0.1 Mo 0.001 Na 10

Nb 0.002 Nd 0.001 Ni 0.002

Tot al P

asPo/- 1 Pb 0.002 Pr 0.001

Rb 0.002 Sb 0.002 Sc 0.005

Se 0.01 Sm 0.001 Sn 0.005

Sr 0.01 Ta 0.001 Tb 0.001

Te 0.001 Th 0.001 Ti 0.1

TI 0.002 Tm 0.00 1 U 0.001

V 0.01 W 0.002 Y 0.001

Yb 0.001 Zn 0.01 Zr 0.002

Tab le 2.Elementsanalysedby lep-MSat BGRwith detection limitsin IJg/L (D.L.).

Table4.The sixmain lith ol ogicalclasses conta in ing sampled bedro ck wells inthe Hord aland area.

NGU -BULL 43 2,19 9 7- PA G E106 GEIRMO RLA N D ET ALIA

Fig.1.Map of southernNorway, showi nglocat io nofthe st udyareas.

The study areas

Figu re 1 showsthe generallocation and sizeof thestudy areas,in the sout hernhalfofNorway.

Hydrochemistry

Hordaland region

The samplesweretaken dominantly fromtheBergen area of Hordaland.The hard rocklitholog ies in the surroundings of Bergen are very variable. In the west and north-west, Proterozoic rocksof the Western Gneiss Region (WGR) are present. Migmatiticgneisses andbandedgneisses of supra- crustalorigin arethe predominant rocks-types;some gab- bros,amphib olite s and granitesarealso present.The rocksof the WGRare overlain by a varietyof allochthonousrocks as- signed to the Lower,Middle and UpperAllochthons of the Caledon iannapp e succession.These rocksarepresentin the so-calledBergen Arcs,amajorconvex-towards-t he-east,arc- likest ruct ureexten din gnotheastwardsfrom Bergen.Within theCaledo nian nappesimportantrock typesinclude diverse Prot erozoic granitoid gneisses, a complex of Proterozoic monzon ite s(mangerit es).anorthositesand gabbros,andlo- cally abundant Cambro-Ordovician phyllite s.NearBergen, phyllites,greenstones,amphi boli tes and metagabbros of EarlyPalaeozoic ageare presentwithin the nappe sequence.

In the southeastern part of the area, southeast of Hardangerfj ord, variousProt erozoic gneissesand metavol- canic rocks, which are part of the Svecono rwegian base- ment ofsouthern Norw ay,are present subjacent to scatte- red outliersof Caledoniannappe rocks consisting mainlyof Camb ro-Ordovician phyllitesandrelated rocks.

Groundwater boreholesdrilled in these different lith olo- giestendtodisplay considerably lesser yields than boreho- lesintheVestfoldarea.Boreholes drilled inthefollow ing lit- hologieswere sampled in theHordaland area:granites,mig- mati ticgneisses,migmati tic amphibolites,migmatitesand metasediments(Table4).

pH

Figure 2 indicates that the distribution of pH is approxi- mately no rmal(i.e. log-normaldistribution of hydrogenion activity).ThemedianpHof theVestfold wate rswas foundto be7.3,allmeasured samplesfallin gin the range6.0to8.4.

Themedian pH inthe Hordalandareais somewhat higherat 7.7,alt hough the rangeis greater,stretchingfrom 5.8to 9.1.

Compared with hard rock lithologiesfrom other areas,e.g.

the Carnmenellisgranite(Smedley1991)or Scilly graniteof Cornwall,U.K. (range5.2 -6.4;Banks et al.1997).these pH valuesare rather high,prob ably due to longer aquifer resi- dencetimes and the fact that maficminera ls inNorw ay's re- cent lyglacially scoured bedrockoutcropshavenot beenre- movedbyprolonge d subaerial weat hering.

Thecorrelation ofpHwithaqu iferlitholo gyis notimme- diatelyclear, althou ghitwill benot edthattwo acidic lit holo- gies(Vestfoldgraniteand Hordaland migmatites)havethe lowest pHvalues.Themigmatit icgneisses,amphibo litesand metagabbros ofthe Hordalandarea are the groups wit h the high estpH.Themajority ofgroundwa te rsfall well wit hin the

z w

o w

NORWAY ~

... Oslo r rv

Veslfold

151;

area L~J

?''' "

. . S '"

Kilometres

JS!jstfansand> .

0 50 100 150

~/ ~-~

s

Vestfold region

TheVestfoldarea is domi nated bythePermo-Carbon iferous Oslo Rift, which comprises Precambrian crystallin e base- ment and Camb ro-Silur ian sedi mentary rocks,including U- rich alum shalesnearthe bottomofthe sequence.Thissedi- ment arysuccession is unconformab ly overlainbyvolcanics (basalts, latites and trachyte s) and sedimentary rocks of Carboni ferous-Permian age. The Precambrian basement complex,as well as the sedi mentary and volcanic cover rocks,are intru ded by young er pluton ic rocks(monzonites, syenitesand granites)of mainly Permian age,such as the DrammenGranite.The volcanic rocks intheOsloRiftare very favourablelit ho log iesforhard rock groundwaterboreho les wit hexceptionally high yields.To the eastand west of the Oslo Rift , auto cht honous Precam brian basement consists mainly of gneisses,granitesand amphibolitesdating from thetim e of theSveconorweg ian orogeny.Borehol esfrom the follow ing lit hologies were investigated in this st udy:

Carboniferou s-Permian latites, basalts. trachytes, granit es andPrecambrian gneisses(Table3).

GEIR MORLAND ET ALIA NG U-B U L L 43 2 , 19 9 7 - PAGE 10 7

p H

~^re

"

^ol"

99.9 n=181

98

~ 90

i

i!! ⁷⁵⁵⁰

25

W-

E 10 13

2

Fig.2.Diagram showing:left,boxp lotsfor distr ib ut io nofpH inbed rockgro u ndwaters, acco rd ing to lithologicalclass (see textfor exp lanation):topright,boxplot sfordistribu- tio nofpHin theVestfold and Hord aland areas:bottomright,cum ulativeprobability distrib utionplot of pHfor the entire dat a set (n=181).#=totalnumber ofsamplesin boxp lo tgrou p.

9.5

pH

OCOOOOCOCOCOCOCOO

I I I I 1 I I I 1 I I

==t-<c<c=:::2: :::2:u.Jecec

<C<C<CCOCf)<:.9<c<:.9Cf)u.Ju.J ffiffi---':5;'i§ :::2::::2: :::2:

tu 2=2=

. :::2: 0 0

c:> -e- ^C") c:>

C") r-- r-- LO r-- ^C'\J r-- r-- "<:t" ^~ r--

=1:1:: =1:1:: =1:1:: =1:1:: =1:1:: =1:1:: =1:1:: =1:1:: =1:1:: =1:1:: =1:1::

9.5 9.0

8.5

c

g

8.0 ^{7.5 7.0} ~~

6.5 6.0 5.5

pH

Parameter Norm Source Hordaland Vestfold Tot al failures/ failures/ failures/

tot al tot al tot al

pH <8.5 1 14/58 0/123 1411 81

>6.5 1 4/58 5/123 9/181

U_BGR <20IJg/L 3 11/58 9/92 2011 50

U_GSC <20 IJg/L 3 10/58 9/92 19/150

Rn <100Bq/L 4 41/56 211/265 252/321

<500 Bq/L 6 15/56 40/265 55/ 321

<1000Bq/L 5 4/56 24/265 28/321

F- <1.5mg/L 1 20/58 40/313 60/37 1

Na <20mg/L 2 34/58 36/92 70/150

<150mg/L 1 4/58 2/92 6/150

Combined Compliance 20/56 18/25 38/81

normsfor Failure 36/56 7/25 43/81

pH,U,Rn (500 Bq/L), FandNa (150mg/L)

Ca <25mg/L 2 16/58 61/92 771150

>15 m g/L 2 29/58 16/92 4511 50 K <12mg/L 1 0/58 3/92 3/150

Mg <20mg/L 1 0/58 7/92 7/150

Ba <100IJg/L 2 2/58 15/92 1711 50

1:Norwegian maximum(orminim um)permitted concentration, Norway(Sosial-09 helsedepartemen tet1995)

2:Norwegianguidelinevalue,Norway(Sosial-09helsedepartementet 1995)

3:Canadiandrinkingwater limit(Barnes 1986) 4:Swedish'concern'level(SIFF1987) 5:Swedi sh maximum level(SIFF1987)

6:Nor wegianrecommended maximum(NRPA 1995)

Tab le 5. Sum mary tab le showing prop orti on of analysed bedrock

groundwatersam p les failingwit hrespecttocited drinkingwaternorms.

limits allowed by the Norwegian drinking water standards (Sosial-og helsedepart ement et 1995),namely 6.5< pH <

8.5, althoug ha minority of samples(13%)fall bot h above and below these limits(Table 5).

Fluoride

Water may be a significant source of fluoride in the diet.It is knownthat fluorideisrequired in certain quantities for nor- mal toothand bone development.Deficiency canresult in malforma tio nof bones anddecreased resistance to dental caries.Severalstudies (e.g.Rock et al.1981) seem to demon- strate that artificial fluoridation of naturally fluoride-poor drinking water can decrease incidence of caries.

Many children areindeed recommended to take fluoride supplementtablets in Norway today.Nevertheless, excessive fluoride may cause negativehealth effects,referredto as fluo- rosis.Dent al fluorosis results in chalki nessand mottling of the teet h,whileosteofluorosi sresults in rough,thickened and chalky bones,particularly in thejaws,fingers and ribs.

Fluorosis may alsocauselamenessand limbstiffnessin catt- le and sheep (it was first observed in volcanic terrain in Icelandin

c.

1000 AD;Shupe etal. 1979).Cases of dentalfluo- rosis havebeenidentifiedby Bjorvatn et al.(1992,1994) in someparts ofwestern Norway, which appearto belinkedto consump tion offluorid e-rich bedrock groundwa te r,ina re- gion where levels may exceed9 mg/L(Bjorvatn 1996, Figure 3).

Previou sstudiesof the regional distribution of fluoride in bedrock groundwater in cool temperate areas include that of Corbett&Manner(1984) in Ohio,U.s.A.,where levels of up to 5.9 mg/L were recorded.In the current st udy, the highestconcentrations wererecorded from theHordaland area (Fig.3),wherearoundonethird(20 of 58)of allsamples

NGU-BU LL 432,1997 - PAGE108 GEIR MO RLA N D ET ALIA

Fig.3.Diagram showing(notethe logscales):

left, boxpl ot s for distribut ion of fluoride (mg/L) in bedrockground waters,accordin g to Iithologicalclass(seetext forexplanation):

top right,boxplotsfordistr ibu tion of fluoride in theVestfoldand Hordalandareas:bottom righ t, cumu lative prob abilit y distribution plot of fluoridefor theentire data set (n = 371).#=tota l num berof samplesinboxplot group.

0.1

0.01

F

99 9

98

~ 90

~

⁷⁵

5- ⁵⁰

J: 25

E 10

il 2

0.1

F

^;;c:i

mgIL

<.0

;a

"<T C\J

=

^{CO C')}

=

^{LD 10}

"<T r-- C\J ^~ ~ C\J r-- r-- ^{"<T ~ ~}

=I:l= =I:l= =I:l= =I:l= =I:l= =I:l= =I:l= =I:l= =I:l= =I:l= =I:l=

10

+

0

T

0

~

c

8~

...J 0

C>

E

0.1

⁺

F

0.01 -'-- - - - - - - - - -

exceeded the Norw egian drink ing wat er lim it of 1.5 mg/L (Sosial- og helsed epart ementet1995)and a maximum con- centration of 9.2mg/Lwas recorded(Table 5).Thesehighle- velsare typicallyderived from the gneissiclithologiesand especiallyfrom the lithologicalgroup MIAM_B,consisting of migmatitic gneisses,metagabbros and amphibolit es. lnthe Vestfoldarea,levels were generallylower,although a sig nif i- cant number of samples (40 out of 313 samples),mostly from the Dram menGranite and some from the lat it es,exce- ededthe 1.5 mg/Llimit(Table 5).

Figu re 4creveals thatin the Hordaland sam ple s ofeleva- ted pH (>8.5)there are conside rab ly elevated conce ntra- tion sof fluoride.ThesehighpH valuesare typ icallyrelatedto themigmatiticgneisses wit hintercala ted bodies of meta- gabbro andamp hi bolite and it is likely that the fluoride is beingderivedby anion exchangefor hydroxide ion s onsites on amphibolesorsheet sil icates.Posit ivecorrelat ion sof flu- oride wit h pHhavebeen observed severaltimes previous ly in Norw egianbedro ck groun dwaters,wit h a similar explana - tion(Banks etal. 1993,Englund& Myhrstad1980).

1 0

10 0.01 0.1

Ca (mmol/L)

0.001

+--.--r-rr---r----r-ro--..--,....,----,,---.. ,

0.001 0.01 ::J - _E ^o _0.1

.§.

LL

600

c Vestfold

500

^{0 ~ Hordaland}

::J 400

-

_...^Ol

E 300

Z

tU ⁰

200

~ 0

1 00

CIJ\:n '!'lOll! ^Ill! 0

0 0 10 20 30 40 50 60 70 80 90

Ca (mg/L)

Fig. 5.

x -v

graphsshowing(notethe log scales)(left)the relationshipbetweencalciumandsodiumconcentration s(mg/L)inthegroundwatersfrom the Vestfo ldand Hordalandareas and(right)the relationshipbetweenmolarconcentrations ofcalciumand fluoride inthesame areas.Theupper line showssaturationwithrespect to f1uoriteaccording to Krauskopf(1979)'s valueofpK,

=

^{10.4while thelow}er line usesNordstrom&Jenne(1977)'s va- lue of 10.96,both at 25°C.Bothlinesareadj usted to T=6°Cusing the Van't Hoff isot herm.Correctionsfor activityhavenot been made.

GEIR MORLA NDET ALIA

10000 10000

0 [ 0V,"oij

j]

⁰

to 8 ...Hodaklind 1000 D

D

.

aB D 0

· ^•

D ElDo"a • 100

.. .

1000 _aDe"'" ^~a a

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^a•

_•

•

.. a olt..D. . . .

. ^.. •

^{·t 10 ..}61fJ~

. J,MJ ... . • •

::J

a-

~~ag~a~ ^a

•

::J

. • ^{... et}

^~~a·.

• l"':

~^{c: 100 oDBD}

a

^a

.

^{<iiI... D g~ ~• DD0}

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^••

. ^•

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.

^{a ••....}_fa~^{a • • •}

·

ex: _{... liD"} 0& :::>

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0.01

.

•

⁰

•

10 0.001

Lt) 0 Lt) 0 Lt) 0 Lt) 0 Lt) Lt) 0 Lt) 0 ^Lt) 0 ^Lt) 0 ^Lt)

Lri cD cD ,...: ,...: _{cO cO cO cO Lri cD cD} ,...: ,...: _{cO cO cO cO}

pH pH

NGU-BU L L432 ,1997 - PAG E109

10 a

. •

^t

•

a ~

.t..

a_{DOg e}aaa"BaDM~_~D 1 • ~.... 1 ^0Oa'" _~

o a 'lPat~

a oB ~El8D o D

~_Cl

.

^{a D.&0Da~lJJDB~~~~D8D0 a}

.s

0.1

·

^{a.eoBa .11aDo0 0..}

LL a _o 1 Cl D...a

U

.

· .

0.01

Lt) 0 Lt) 0 Lt) 0 Lt) 0 Lt)

Lri cD cD ,...: ,...: _{cO cO cO cO}

pH 10000

.

g

1000

D

.

^1'".....

• a~ ~.",:.

· . "

~

.

Cl • L'

~"'aD t. ~ • •

^a

E

·

C,

•

^a. ~

. ^".

E 100

• . .

CO

D

z

tu 10

Lt) 0 ^Lt) 0 eo 0 Lt) 0 eo

Lri cD cD ,...: -; cO cO cO cO

pH

1000

... .

100

0.1

+--.---.---,-,..-..,.----.----.---,

~ 0 ~ 0 ~ 0 ~ 0 ~

~

w w

~ ~ 00 ~

m m

pH

100

10

.

^a _XDD~""0

0 .to ..^0..

.~ ₁

. _•

^a.

Cl

•

... ... t:&.'"

r

.§ ... ... 'l4 ...

: "'t

Cl 0.1 ^~.

E ^a

.

^l _{t •}

ell

•

^{0 • a}

~

^{0.01 .A,.}

o •

0.001

Lt) 0 Lt) 0 _~ 0 Lt) 0 eo

Lti cD cD ,...:

...

cO cO cO cO

pH

Fig.4. XYgraphs (notethelogscales) sho- wingthe relationsof(a) Rn,(b)U(Canadian values),(c)F-,(d)B, (e) Na/Br ratio and (f) Ca/NaversuspH for thedata setsfrom the VestfoldandHordaland areas.

Figure 5revealsno clear corr elat ion of F- wit h Ca,alt- houghitwill benot edthatthemost fluor ide-and calcium- richwatersimpinge uponthe line defining fluoritesatura- tion.A plausible model forfluorideevolutionin thesewaters thus involves the derivation of fluoride by anion exchan ge on amphiboles,sheet silicates and,possibly,apatite,at eleva- tedpH,wit hanupper limitbeingdefined by the locusof flu- orit e satu rati on.Anotherpossib lesource offluorid e maybe influorit ewit hin the rockmatrixoras a fracture mineralisa- tion.

Radon

Apparent correlationshave emerged betweentheincidence of lung cancerandthe concentrat ionof radon inhousehold air.Hit hert o,some 20 epidemio logical studieshave been carried outinmines(includinguranium mines)andsome30

studies inresidential environment s.Themost important of thesearedescrib ed byICRP(1993),UNSCEAR (1994), Lubin et al.(1994),WHO(1996) andLubin &Boice(1997).Although radon- containingwaterwas once thoughttohave posit ive health-effects(Albuet al. 1997),there now exist epidem iolo- gical studies which appear to linkradon concentration in waterwith incide nce of gastric cancer (Mose et al. 1990).

Waterwit helevated radonconcentrationscan,accordingto recentresearch,result in significantradiationdoses,particu- larly for youngchil d ren(UNSCEAR1993, Swedj emark 1993).

Hit herto ,the highest radon activi ty(8,500 Bq/L)docu- mented from Norwegian groundwaters was from the Precambrian Iddefjo rd Granite of sout h-eastern Norway (Banksetal. 1995b). In recent month s,theNRPA havealso analysed a ground water sample from the same lit hology, nearthetown ofFredrikstad,wit hanactivityof 19,900Bq/L

NGU-BU LL 432,1997 - PAGE110 GEIRMO RLAN D ET ALI A

Bq/L

Fig.6.Diagram showing(note thelog scales):

left,boxplotsfor distributionof Rn(Bq/L) in bedrock groundwaters,according tolitholo- gical class (see text for explanation): top right,boxplots for distribution of Rnin the Vestfold and Hordalandareas:bottomright.

cumulative probability distribution plot of radon for the entiredataset(n

=

^321).#

=

^to-

tal number of samples in boxplotgroup.

i

i

+

n=321

100 10ClJ llXXXl

0.1+-..,,--rr---'-"'TTr--"'r-rn

0:>

10-'-- -'-- - - - - -

R n

98 99.9

R n

~ 90

g 75

~ 50

.t

²⁵

~ ¹⁰

o

+

O COOOOCOCO CO COCO O

I I I I I I I I I I I

= = I - < c < c = : : 2 : : : 2 : U J a : a :

<C<C<CCOCf)(9<C(9Cf)UJUJ a : a : - l < c < c - - - I - = = (9(9 -lco::2:::2:::2:UJI- I- ::2: 0 0

10 -'--- - - -1-1- - - - - - 1 00

1 000 1 0000

R n

10000 10000 HordaJand

~ cgCb c Vestfold

'"

B CC~ec

ccC 1000

1000 _c~ c ~~~ ^{cf o ic} ~

::J' _{c .. .}

'MU

~ ~.I-

:2'

0-

~ c"

^{cf i 0-}

~_c .A." _iOl

~-'B

[],; ....[] ..CC ^~C

a: ^{.. .4} ~^{B lIIl} q~ [] .. a:

100

100 800I] 8 re.&. 0 ...

o ~o ... ..

cc ~

c ccc

cc cc cac. ~

~

10 10

0.01 0.1 10 0.001 0.01 0.1 1 10 100 1000 10000

F(mg/L) U(ug/L)

1000 100

~I#> ~ ~

~ c

~ ~ 10

100

~

:2'

^{~ u d'}

::J' 0>

... ""c .",': .

C> 10 ^2- 0.1 ^'\ .q. "'.

::J

F

^c

^{l ·}

^{1~ e}

en ^c_c ~ ^e .c';,...~c ^{. :}

0.01 ^{c Pnc ..A .. 0 ...}

C C oca._~De c 0

~ D cr:rJ p qJ8Ic 0 ...

HordaJand ^{~ ~c e c c}

0.001 ^~

~OD •

•

0.1 0.0001

0.01 0.1 10 0.001 0.01 0.1 1 10 100 1000 10000

F(mg/L) U(ug/L)

Fig.7.X-Vgraphs(notethe log scales)showi ngcovariation(a) ofF- and Rn,(b) of U and Rn, (c) of F and B and(d) of U and Thin thewaters from the Vestfo ldandHordaland areas.

GEIRMORLAND ETALIA NGU-BUL L432, 19 9 7- PAGE111

(Lind 1997).Almost 80%ofsam ples takenfrom thislithology exceeded 1,000 Bq/L according to thedataof Bank s et al.

(1995b).Thesevalue s are modest, how ever,compared wit h the maxima recorded indrin king wate rin Sw eden (57,000 Bq/L -Akerblom&Lindg ren 1996)and Finland(77,500Bq/L - Salo nen 1994).

Swedenoperates wit ha«concern» levelof100Bq/Lfor municipal drinking water,abovewhic h it is recom mended thatthe possibleeffects of theradon on water users should be considered.For groundwater ext ract ed from a private boreholeto useina single household,the sim ilar limit is 500 Bq/L.Sweden has a maximum lim it of 1,000 Bq/L, above which act ion to lim it thedose fromrad onis recom men ded (Statensstra lskydd sinstl t ut 1996).Norwayhasrecentlyintro- duced a recommended maximum level of 500 Bq/L(NRPA 1995).Theselevels are basedon radi ation dosesto children and adultsdue to ingestionand inhalation of degassedra- don (St rand&Lind 1992).Forchild ren,ingestion results in themost sign ifican t dose;for adults,inhalatio nis thecrit ical pat hw ay.

On the basis of56 boreholes in the Hordalandareaand 265 borehol es in theVestfo ld area(Fig.6),arou nd 80% of boreholes(252out of321) had a radonact ivit y of morethan 100 Bq/L,whi lesome 17%(55 out of 321)had a concentrati- on above 500 Bq/L.The high est recorded levelwas 6840 Bq/L. The most problem atic litholog ical group from the point of view ofrad on are the Vestfoldgranites,dom inated by thePerm ianDramm en granite,where almost90%of all borehol es exceeded 500 Bq/L and over50%of all boreholes exceeded 1,000 Bq/L.The low estradon act ivit iesare related to thebasalts of theVestfoldarea.Thelatitesandrhomb per- phyrieswhich, with their relatively high permeability,form the dominant bedrock groundwat er supp ly around

Oslofjord, exhibit radon concent rat ions typically in the range 100-500Bq/L.

Figure7a suggests thatthere are a sig nificant number of cases,especially in theVestfo ld area wherehig h Rn isaccom- panied by high F- concentra ti ons.Posit ivecorrelat io n bet- ween Rn andF-has been noted byBanks et al.(1995a,b).A possiblecoexistenceoffluo ride and uranium in variousmi- neralassemblages (e.g.apatite,sheet silicatessuch asbiot i- te)is wellknown. No radiumanalyseshave, as yet,been per- formed on thewaters,but Strand & Lind (1992) note that there isgenerallynoclearcorrelat io nbetwe en radonand ra- dium in Norw egiangrou nd wat er.

Uranium and Thorium

Previously,thehigh est reported uranium concentration in Norwegian bedrock groundwater was from the Iddefjord granite(170~g/L-Banks et al. 1995b ),whilelevels of over 14 mg/L have been reporte d from granites near Helsinki in Fin land(Asikainen&Kahlos 1979).Forthorium ,Banks etal.

(1995b) repor ted a maxim um of 2 uq/L No Norwegia n drinking waterlimitexistsfor uraniumor thori umwhereas Canada uses a maximum of 20 ~g/L for uraniu m (Barnes 1986).

In this survey, uranium wasdet ermined by ICP-MS both in Canada and Germ any.Below 100~g/L,the inter-laborato- rycalibrat ion is good. Above thislevel, theCanadian results exceed the BGR results to a deg ree which increases with concentration.The high est concentra ti on was found in a sam p le ret urn ing avalueof some 2,020 uq/l, fro m Canada and890~g/Lfrom Germany.In thediagrams and in the sub- sequent discussion,theCanadianvalues for uranium areci- ted as these are thevaluesmeasuredshortly afte rsam pling.

The distribution of uranium seem sto follow thatofra-

0.001 -'-- - - - - - - - - -

Fig.8.Diagramshowing(notethelogscales):

left,boxplotsfor distributi onof U(uq/L)in bedroc kgroundwater s,accordingtolith olo- gical class (see text for explanation):top right,boxplots for dist ribut ion of Uin the Vestfo ldand Hordaland areas:bottomright , cumulative prob ability distribution plot of uranium forthe ent ire data set(n

=

150).#

=

totalnumb er ofsamplesin boxplotgroup.In allcases,the figuresreferto uraniumanaly- sescarriedout byG5Cin Canada.

ugIL ~ ~

10000

1000 ⁺

.

~ ^.

100

~

10

0.1 0.01 0.001

U i

^~

I

99.9 n=150

98

e:

⁹⁰

[

⁷⁵

El- ⁵⁰

i!! 25

u,

E 10 B

2

0.1

8

^;:;

-

^:= § §

~

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es ^{d d} uglL

0 r-- ^e') 0 0

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10000 1000

0

100

⁰

1 0 -

~

...J

: ~ =

0>

:::J -

0.0 1 0.1

u

NGU-B UL L 432,1997 -PAGE 112 GEIRMO RLA N D ET ALIA

100

Fig. 9.XV-diagramshowing(note thelogscale)thecorrelationbetweenU andpHin thePermianlatites/rhomb porphyry lavasfromVestfold.

dance with Banks et al.(1995 a.b,1997),andindicates that, although U content in aquifermaterialmay act as a coarse control on both dissolved Rn and U contents in ground- water,ot herfactorssuch as residencetime,fracture aperture, redoxconditions or weathering history controlthe distributi- on of these parameters with ina given aquifer type. There may be a weak positive correlation of Uwit h pH(Fig.4b).The correlatio n is considerably stronger in the Permian lat ites and rhomb porphyrylavas from the Vestfoldarea(Fig.9).

Thorium in groundwater seemsto exhibit a veryweak positivecorrelation with uranium (Fig. 7d),probably reflec- ting a coarseeo-variat ionin Th and U conte ntinhost rocks.

Thoriumis generallyrather insoluble,particularlyso in redu- cingcondit ions, hence redox potent ial islikelyto be amajor factorin controllingthoriumdistribution in groun dwater.ln thissurveyalmostallsamplescontainthoriumatless than 1

~g/L,alt hough a single sample from the Hordalandgranites returned a value of some 20~g/L(Fig.10).Againthehighest concentrations are derived from the acidic lit hologi es (gneisses and granites).Thelow solub ilityofThprobablyim- pliesthat it posesless of a concern in thecontextof human healththan U or Rn,butgiven that Th is significantly more toxic than either U or Rn,the health impact of~g/L-Ieve lsof Thcannot necessarilybe disregardedasinsignificant.

Boron

Boron is an essentialelement for plantsbut becomes phyto- toxic in high concentrations.Concentrationsof boron may thus be of concern regardingthe use of groundwaterforirri- gation.ltsessentiality for human healthhas not been clearly demonstrated,butit s utilityas a tracerof sewag e leakage or of leachate from waste disposalsitesrenders knowledgeof background concentrationsin ground wat erof considerable

8.5 7.0 7.5 8.0

pH 6.5

0.01

--+---,--,---,--,---,--,---,--,---,---,

6.0

10

^{o 0}

- . ....J

^{o 0 0}

-- ^0>

^:::J

...

:::>

0.1

donquit eclosely(Fig. 7b).Figu re 8 shows thatthehighest concent rations(withamedianof some 100~g/Land amaxi- mum of 2 mg/L)are from theVestfo ld granit es.The next

highest levels are from the Hordaland granites.Some 13%

(19 out of 150 samples) of all ground waters exceed the Canadian limitof 20uq/L and these aredominant ly from the granite litholo gies.Although there exists a clearcorrelation betweenRnand U for the totaldataset (Fig.7b),this ismain- lyduetothe large differences inRnand U grou ndw atercon- tents between the differen t lithologies(Figs 6 and 8),rather than to correlation withina given lithology.This is in accor-

0.0001 ...L.-- - - - - - - - - -

Fig.10.Diagram showing(note thelog sca- les):left.boxplot s fordistributionofTh(\Jg/L) in bedrockgroundwa ters,according to litho- logicalclass(see text for explanation):top right.boxplots for distribution of Thin the Vestfold and Hordalandareas:bottom right, cumulative probability distribution plot of thoriumforthe entiredata set(n

=

^150).#

=

total numb er of samplesinboxplot grou p.In all cases,the figures refer to thoriumanalyses carriedout by BGR in Germany.

10

o.: ~ _ +_ !

0.01 0.001

ugIL

00

0.0001

-g

I

Th

~_:£ :>

99.9 n=150

98

~ ⁹⁰

~ 75

'"

⁵⁰

~

s

²⁵

~ ¹⁰

0.1

§ 8

o "'"":

-

^~ §

Th

₀ ^{0 ouglL}

+

c:::> r- ^(") c:::> c:::>

..- r- ^{<0 ..-} "<:T ^('\J r- r- "<:T ..- ..-

'*'*= '*'*= '*'*= '*'*= '*'*= '*'*= '*'*= '*'*= '*'*= '*'*= '*'*=

100 10

+

0.001 0.01

T h

- l

g, 0.1

GEIRMORLAND ETALIA NG U-BUL L 432,1997 -PAGE 113

10 100

0.1 -g

j

B ~

~

99.9 n=15O

98 Fig.11.Diagram show ing (notethe log sca-

~ 90 les):left,boxplotsfordistributionofB(f.lg/L)

g

75 inbedrock grou ndwa te rs,accordingto litho-

§. 50 logicalclass(seetext forexplanation): top

J: 25

E 10 right,boxplotsfor distribution of B in the

e _Vestfoldand Hord aland areas:bottomright,

2 cumulative probab ility distribut ion plot of 0.1 boronfor the entiredata set(n=150).#=to-

o §

§

^{tal number ofsamples}in boxplot group.Inall

B ^d ugIL

cases,the figures refer to boron analysescar- riedout byBGR in Germany.

C> t - ^Cl) C> C>

..- t - <0 -.::r ^C'-I t - t - -.::r ^{..- ..-}

'**= '**= '**= '**= '**= '**= '**= '**= '**= '**= '**=

1000 ¹⁰⁰

⁰

- ~

~

- l

~ ~

0>^:::J

10

0.1 -'-- - - - - -- - - - -

interest.Studies ofasingle lithology,the IddefjordGranit e, by Banksetal.(1993) indicatethatboronin ground waterin coastal regio ns ispartlyderivedfrom marin e salts inrechar- ge water andpartly fromwater-rock interaction.Boroncon- cent rat ions recorded inthis survey vary between approxi- mately1 IJg/Land 850 IJg/L(Fig.11).Boron shows a positive eo-variation withpH(Fig.4 d)andalsowit hfluoride (Fig. 7c).

As wit hfluori de,thehighestboronconcentr at ions areclear- ly derivedfrom thelit hological groupcont ainingmigmatitic gneisses, amphibolit es and metagabb ros from the Hordalan darea.

Sod ium and Calcium

Both sodiumand calcium have been regarded as problema- tic parametersin the contex tof Norwegia ngroundwater re- sources for some tim e.TheformerNorw egian guidelinele- velfor sodium(SIFF1987) was setatalevelof only 20 mg/L, whichwas freq uent ly exceeded inthebedrock groundwater ofa countrywith a high degree of marine influence(airbor- ne and relict marine-derivedsalts in recharge water)and an abundance of rocks containingsodicplagioclase.The maxi- mumconcent rat ion forsodium has been recently definedat the more realisticlevel of 150mg/L,althoughthe guideline valueof20 mg/Lisretained (Hellesnes 1995,Sosial- oghel- sedepart ement et 1995).

Calcium has also long been regarded as undesirable from an aestheticpoint of view in Norway,due toscaling of kettles, and problems wit h foaming of soap.Former guide- lines(SIFF 1987)stipulatedmaximum limi ts for calcium in, despitethe fact that calcium is not regarded astoxic in drin- kingwater.This despite the fact thatseveralotherEuro pean nationshave set minimum levels for hardn ess in drinkin g water,aconcept now accepted in Norway (see below).These

minimumlevelshave been ostensiblyprom oted bytheob- servation thatthe incidenceofheartdiseaseinseveral coun- tries,suchas the UK (Crawford et al. 1971,Lacey1981)and Norway(Glattre et al. 1977).is inverselycorrelated wit h wa- ter hardness.Thereasons for this remain unclear,although severalpossible explanatorymodelshave beenproposed:

•Calcium-richwaters are often poor in sodium,a high di- etary conten t of whichis knowntoexacerbatehyper- tensive disorders.

•A high water hardnesshinders the solubility of many toxic metals,such aslead,which otherw isemay be so- lubilisedfrom geological materialsorfromthe distrib u- tion network(Crawford & Clayton 1973).

•Heavy industry,particularlyinthe UK,has grown upin areas wit hsoftwater suppliessuita blefortext iles ma- nufact ure and boilerfeed water (Le.itisthe industria l environmentrather than thewaterper sewhich leads to the disease).

Currently, Norway advises a guidelinerange of 15-25mg/L for calcium,yet(slight ly perversely)setsa minimum level of 60mg/Lcalcium-equivalents(Ca or Mg)for artificially softe- nedwater(Sosia l- oghelsedepart ementet1995).

Figure 12displaysthe sodium concent rationsrecorded durin gthis st udy.It will benot ed thataround50%ofwaters (70 out of 150)exceedthe Norwegianguidelineof 20 mg/L and 4%(6 out of150)exceed the limit of 150 mg/L,while the maximumobserved concent rat ion is 508 mg/L.Banks et al.

(1993) demonstrated thatsodiumingroundwa terin a coas- talgranite litholog y waspartly derived from marine salts (from precipitationor direct intrusio n) butwas in many ca- seslargely derived from silicate weat hering or possiblyion