MOONMILK IN POSTOJNA CAVE PRECIPITATES UNDER ISOTOPIC MOONMILK IN POSTOJNA CAVE PRECIPITATES UNDER ISOTOPIC JEQUILIBRIUM CONDITIONSEQUILIBRIUM CONDITIONSQ

1 2 3 4 5Magda Mandić1, Andrej Mihevc2, Albrecht Leis3, Tea Zubin Ferri4 , Ines Krajcar Bronić5Magda Mandić , Andrej Mihevc , Albrecht Leis , Tea Zubin Ferri , Ines Krajcar Bronić

1 D f Ph i U i i f Rij k Rij k C i 3J R h I i G A i1 Department of Physics, University of Rijeka, Rijeka, Croatia; 3Joanneum Research Institute, Graz, Austria;p f y y f j jmmandic@phy.uniri.hr 4Research Centre METRIS, Istrian Development Agency (IDA) Ltd.;mmandic@phy.uniri.hr Research Centre METRIS, Istrian Development Agency (IDA) Ltd.;

2Karst Research Institute Postojna Slovenia; 5Ruđer Bošković Institute Zagreb CroatiaKarst Research Institute, Postojna, Slovenia; Ruđer Bošković Institute, Zagreb, Croatia.

Summary First description of moonmilk in Postojna CaveSummary First description of moonmilk in Postojna CaveA part of a comprehensive multidisciplinary study of Postojna Cave, Slovenia,

Because this is the first time that moonmilk isA part of a comprehensive multidisciplinary study of Postojna Cave, Slovenia,(Figure 1) related to modern speleothem formation conditions (Mandić 2013) is

described in Postojna Cave, the investigation of(Figure 1) related to modern speleothem formation conditions (Mandić, 2013) is

t d O it i d t d t i l ti ithi described in Postojna Cave, the investigation ofits origin has started

presented. One year monitoring was conducted at nine locations withinits origin has started.Postojna Cave in order to determine environmental conditions of carbonatePetrographicaly, the moonmilk is composed of

jdeposition g p y, p

calcite needles approximately 100 µm long anddeposition.

calcite needles approximately 100 µm long, and10 id (Fi 2)10 µm wide (Figure 2).SEM micrographs of moonmilk show evidence ofSEM micrographs of moonmilk show evidence ofmicrobial biomediation or bioprecipitationmicrobial biomediation or bioprecipitation(Fi 3)(Figure 3).

Figure 2 Calcite needlesFigure 2. Calcite needles

Figure 1 Monitored locations within Postojna Cave Slovenia with a detailed plot of Figure 1. Monitored locations within Postojna Cave, Slovenia with a detailed plot of i l ti Z ji T tmicro location Zgornji Tartar

Modern carbonates mostly soda straw samples were collected and their stableModern carbonates, mostly soda-straw samples, were collected and their stablei t iti (13C d 18O ) d t i d Th t f Fi 3 A di t h d i (1 ) th i id f b t i l i tisotope composition (13Cc and 18Oc) was determined. The assessment of Figure 3. According to shape and size (1 µm) there is evidence of bacterial existence

ATR FTIR* l i (Fi 4)process (equilibrium or kinetic) of precipitation for modern carbonates was done

ATR-FTIR* analysis (Figure 4)p ( q ) p pby comparing these values with isotopic composition of water (18O ) and of y

pertains to presence of organicby comparing these values with isotopic composition of water ( Ow) and ofdi l d i i b (DIC 13C ) d diff b t 13C pe ta s to p ese ce o o ga c

compounds (Bullen et al 2008dissolved inorganic carbon (DIC, 13CDIC): measured difference between 13CDIC

13 compounds (Bullen et al., 2008,A l d E Mi bi l

and 13Cc was compared with the theoretical fractionation ε value; fractionationAppl. and Env. Microbiology,c p

factor () calculated from the measured 18O and 18O values was compared74, 4553-4559 ). It has to be

factor () calculated from the measured Ow and Oc values was comparedwith the equilibrium fractionation factor for the measured temperature; , )

distinguished whether thewith the equilibrium fractionation factor eq for the measured temperature;

f b i i i l l d f h i i 18O distinguished whether theorganic compounds found in a

temperature of carbonate precipitation was calculated from the isotopic 18Oorganic compounds found in a

lk l l fcomposition of carbonate and water and compared with the measured

moonmilk sample are a result ofco pos t o o ca bo ate a d ate a d co pa ed t t e easu edtemperature Even thou the temperatures of calcite precipitation calculated by p

cave micro-organisms (native)temperature. Even thou the temperatures of calcite precipitation calculated by

i diff t ti ll d t ith th d cave micro organisms (native)or of allochthonous species To

using different equations generally do not agree with the measuredor of allochthonous species. To

l t f th ttemperatures at given locations, research has resulted in finding locations and

rule out one of the twop g , g

samples which are promising candidates for paleoclimate investigationspossibilities, a sample is given

samples which are promising candidates for paleoclimate investigations.Figure 4 Wavenumbers 2876 and 2985 cm-1p , p g

for RNA sequencingFigure 4. Wavenumbers 2876 and 2985 cm

i di t th f i tt i lfor RNA sequencing. indicate the presence of organic matter in a sample

Monitoring results at location Zgornji Tartar *ATR-FTIR: Attenuated total reflectance Fourier transform infraredMonitoring results at location Zgornji Tartar

Location 09 Zgornji Tartar (“Upper l l iLocation 09 – Zgornji Tartar ( Upper” ) d h

Temperature calculationTartar” or Tartarus) is situated in the

pT bl 1 Th l l l t d f d δ18O l f d i t

)part of the Postojna Cave which is Table 1. The values calculated from measured δ18O values of drip waterpart of the Postojna Cave which isisolated from tourist visit The and recent carbonates in Postrojna Cave and comparison with theisolated from tourist visit. The

li l ti (Fi 1) i i

j pequilibrium values sampling location (Figure 1) is in a

E ilib i l equilibrium eq values.

vicinity of Stara apnenca collapse Equilibrium values, eq values for recent y p pdoline Location was in previous

values for recent carbonatesdoline. Location was in previous

ti d li ti i fl fcarbonates

times under climatic influence of anO'Neil et al Friedman Kim et Coplen, Chacko and Tremaine

opening which is nowadays closed O Neil et al., 1969;

Friedman and O'Neil,

Kim et al., 2007

Coplen, 2007 Deines, 2008

Tremaineet al., 2011p g y

by sediment (Gospodarič 1976 Acta n

,1977

, ,

by sediment (Gospodarič, 1976, ActaCarsologica 7 5 135) Distance from at

ion

(ºC

)

“Soda straw”Peculiar growth Carsologica 7, 5-135). Distance from

hi i 110 d f h Loc

a

t air

( Soda strawg

typesthis entrance is 110 m and from the L t

main entrance to Postojna Cave ismain entrance to Postojna Cave is1970 m1970 m. 01 9.8 1.0318 1.0323 1.0331 1.0334 1.0318 1.0328 1.0345 1.0360

02 9 9 1 0318 1 0323 1 0331 1 0334 1 0317 1 0328 1 0341

M i t t (Fi 5) t02 9.9 1.0318 1.0323 1.0331 1.0334 1.0317 1.0328 1.0341 -03 9.7 1.0318 1.0324 1.0331 1.0335 1.0318 1.0328 1.0347 -Mean air temperature (Figure 5) at 03 9.7 1.0318 1.0324 1.0331 1.0335 1.0318 1.0328 1.034706 11.3 1.0314 1.0320 1.0327 1.0331 1.0314 1.0325 1.0326 -

location 09 – Zgornji Tartar is 10.7 ± 07 10.7 1.0316 1.0321 1.0329 1.0332 1.0316 1.0326 1.0337 -g j0 9 ºC The mean water temperature

08 11.6 1.0314 1.0319 1.0327 1.0330 1.0313 1.0325 1.0337 -09 10 7 1 0316 1 0321 1 0329 1 0332 1 0316 1 0326 1 0341 1 03320.9 C. The mean water temperature

is 10 9 ± 1 0 ºC The drip rate 80 ± 10309 10.7 1.0316 1.0321 1.0329 1.0332 1.0316 1.0326 1.0341 1.0332

is 10.9 ± 1.0 ºC. The drip rate 80 ± 1031 f 1 The values (Table 1) are higher than the equilibrium fractionation factors eqmin-1 varies from 19 to 300 min-1. The values (Table 1) are higher than the equilibrium fractionation factors eq

i b i h O l t l ti 06 St b išč d 09 Z ji T tMean pCO2 is 937 ± 325 ppmv. Mean given by various approaches. Only at locations 06 – Stebrišče and 09 – Zgornji TartarMean pCO2 is 937 ± 325 ppmv. Meanvalues of conductivity pH and pCO the two values are comparable.values of conductivity, pH, and pCO2

313 123 S/ 7 8 0 3 d

p

are 313 ± 123 µS/cm, 7.8 ± 0.3, and Table 2. Comparison of measured temperatures and temperatures determined937 ± 325 ppmv, respectively. Mean

p p pfrom 18O of water and carbonates under assumption of precipitation under pp , p y

values of magnesium calcium andfrom O of water and carbonates under assumption of precipitation under

i t i ilib i ditivalues of magnesium, calcium andbi b t t ti 0 8 ±

isotopic equilibrium conditions

on Measured Calculated temp. Range, (°C )bicarbonate concentrations are 0.8 ±Type Reference Equation Source

cati

o Measured temperature

p g , ( )0.2 mg/L, 76 ± 4 mg/L, and 215 ± 24

Type Reference Equation Source

Loc

p( °C ) Soda

t „Peculiar” types

g/ , g/ ,mg/L respectively The mean 13C Epstein and Mayeda, 1953 t(ºC) = 16.5 – 4.3 D + 0.14 D2 OrganicL straw „ yp

1 0 3 5

mg/L, respectively. The mean Cvalue in DIC is 13 01 ± 0 75 ‰ The C i 1965 t(ºC) 16 9 4 2 D+ 0 13 D2 O i01 9.8 -1.0 - 3.5 -2.1 -1.0value in DIC is -13.01 ± 0.75 ‰. The

13C ( 16 1 3 2 ‰)Craig, 1965 t(ºC) = 16.9 – 4.2 D+ 0.13 D2 Organic

02 9.9 0.7 - 5.0mean 13C in air is (-16.1 ± 3.2 ‰).t(ºC) = a bD + cD2 Shackleton, 1974 t(ºC) = 16.9 – 4.38 D+ 0.10 D2 Organic

03 9.7 -1.8 - 2.8

( )t( C) = a – bD + cD2

D 18O 18O

06 11 3 5 7 - 10 3D 18Ocarb - 18Owater

18O in VPDBGrossman, 1982 t(ºC) = 16.4 – 4.2 D+ 0.13 D2 Inorganic-5.0 06 11.3 5.7 10.3

07 10 7 2 0 6 0

18Ocarb in VPDB,

18O in VSMOW07 10.7 2.0 - 6.0

Figure 5 Monitoring results on Owater in VSMOW Mulitza et al., 2003 t(ºC) = 14.32 – 4.28 D+ 0.07 D2 Organic-5.5

08 11.6 0.5 - 4.7Figure 5. Monitoring results on l i Z ji T Leng and Marshall 2004 t(ºC) = 13 8 – 4 58 D+ 0 08 D2 Inorganic6 0)

09 10 7 1 0 - 5 1 Moonmilklocation Zgornji Tartar Leng and Marshall, 2004 t( C) 13.8 4.58 D+ 0.08 D Inorganic-6.0

DB

)

09 10.7 1.0 - 5.1 7.4 - 7.8 Andrews, 1994, 1997 t(ºC) = 15.7 – 4.36 D+ 0.12 D2 Inorganic-6 5V

PD

-6.5

(‰,

-7.0carb (

Figure 6 13C and 18O composition 13C

c

Figure 7. Observed mean annualFigure 6. 13C and 18O composition f ilk f l i 09

-7.5

gair temperature in caves (Lacelleof moonmilk from location 09 air temperature in caves (Lacellet l 2004 C J E th S i 41

-7 5 -7 0 -6 5 -6 0-8.0 et al., 2004; Can. J. Earth Sci. 41:

7.5 7.0 6.5 6.0

18O (‰ VPDB)1411-1423) versus calculated

Ocarb

(‰, VPDB))

mean annual air temperaturemean annual air temperaturederived from the 18O values of

Mandić M 2013 Determination of equilibrium conditions of carbonate precipitation in Postojna Cave derived from the 18O values of

ilkMandić M., 2013. Determination of equilibrium conditions of carbonate precipitation in Postojna Cave with possible application to paleoclimatology Ph D Thesis Zagreb University of Zagreb 205 p

moonmilkwith possible application to paleoclimatology. Ph.D. Thesis, Zagreb, University of Zagreb, 205 p.

SINA, 12th Austrian Stable Isotope Network Meeting, 15th & 16th November, 2013, Graz .