Plasm a Winter Conference 2003 Poster No.: P- LA- 014

(1)

SN-I CP-MS

Elem ent LA¹ HNO32 tri-acid³ I C⁴ Literature⁵ Na 49.3 ±24.5 77.649 175.005 88.280 84.030 Mg 63.5 ±41.6 102.855 121.427 50.020 37.920 Al 253.8 ±172.5 163.689 441.318 - 270.000 K 89.8 ±60.4 16.746 122.272 10.560 17.050 Fe 196.0 ±128.8 137.271 253.550 - -

Zn 2.2 ±1.7 16.282 20.196 - 0.563

Cd 0.054 ±0.036 0.126 0.137 - 0.003 Pb 0.317 ±0.217 0.946 1.170 - 0.151

Hamtser samples

P1 P2P3 P4P5 P6P7P8 P9P10 P11P12 P13P14 P15P16 P17P18 P19P20 P21 10⁵

10⁶ 10⁷

intensity [cps]

scan no.

13C 48Ti 13C glass blank 48Ti glass blank

T1impl ^{1 2} 3 4 5 6 7 89 10 11 21 20 19 18 17 16 15 1413 12

7

8

9 1415

16

glass pale tissue darker, thicker tissue darkest tissue area of hamster tissue sample

object slide

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35 mm

increase depth and age of ice sample

area scan (20 mm²)

average:

area scan literature

min max

max min min max core axis

object slide ice sample

K1K

0 200 400 600 800 1000

1 10 100 1000 10000 100000 1000000

time [s]

intensity [counts s-1] LMNOMPQNRSNMTPU

RNLTVSTUW WUXPQNRSNMTPU YOPQQ

RNLTVSTUW

17OH ¹⁰³Rh ²⁰⁸Pb ²⁴Mg

Z [\(]^(_

Signal of 10 µgkg^{- 1}"daily perform ance" ice st andard at different m asses. ¹⁷OH is used as int ernal st andard.

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Alfred-Wegener- I nstitut e for Polar and Marine Research,

Am Handelshafen 12, D-27570 Brem erhaven, Em ail: hreinhardt@awi-brem erhaven.de

* I nstitute of Spectrochem istry and Applied Spectroscopy, Albert-Einstein-Str. 9, D-12489 Berlin-Adlershof

Plasm a Winter Conference 2003 Poster No.: P- LA- 014

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The experim ental setup is shown in ^x. To enable direct analysis of solid ice sam ples at a tem perature of -45°C a cryogenic laserablat ion cham ber (CRYOLAC^TM, Germ an patent application) was constructed. The cham ber has a large volum e (^5¡5¢^£) to enable the m easurem ent of ice core sam ples cut as discs or segm ents with one or m ore annual layers depending on the depth of the ice origin. The inner part of the cham ber consists of high purity copper and cont ains a cooling canal for the cooling liquid (silicon oil). The outer shell consists of teflon and enables a good insulation against the copper block. A com put er controls the sam ple stage of the laserablat ion cham ber in xyz- orientation as well as the laser system .

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The direct determ ination of elem ent signat ures in polar ice core sam ples from Greenland by laser ablation I CP-MS has been investigated. I ce core studies enable a highly resolved reconstruction of Earth clim at e back to about 500,000 years. The analysis of trace elem ent signatures and dust horizons along annual layers yields inform ation about the strength of sources and transport m echanism s for aerosols in the paleoatm osphere as well as about the paleovolcanism . Annual layers and transitions from cold to warm periods are det ectable due to changes in concentrat ion of m ineral dust and seasalt.

Up to now elem ent analyses in ice cores are only possible with m olten ice sam ples. Drawbacks are:

• High sam ple consum ption

• Low spatial and tem poral resolution

• Lost of valuable sam ple m aterial

The aim of this work was to achieve a m ultielem ent determ ination of elem ent signatures in ice cores with a higher spatial resolut ion especially in thin annual layers (< 0.5 cm ) of old deep-ice.

Laser ablation I CP-MS is the first analytical technique which fulfils the detect ion of elem ents at ultra trace level in thuch thin layers with the required resolution. Advantages are:

• Spatial resolution + detection lim its

• Low sam ple uptake

• Analysis directly from solid sam ple

¯ Minim um sam ple preparation

¯ Low risk of cont am inat ion

I n this study the elem ent det erm ination in real ice sam ple m aterial is focused to following com ponents:

°

7±"²lb³«´5£* rµ 5¢ ¶ *·£5¶

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½7 Ã5¶Ä1Å*Ä35£5½5·l¶ *·(£5¶

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• For calibrat ion, ice standards were perform ed in a stepwise procedure from com ercially available standard solutions.

• The signal of ^É^Ê^ËÍÌ com ing from the ice was found to be m ost suit able to use as an ^½7^£5¶^½* 5¢*µ^5½*¾1 5¶^¾.

• A study of ¹⁷OH, ²⁴Mg, ¹⁰³Rh and ²⁰⁸Pb signal progressions (laser ablation line scan m ode) is dem onstrated in ^¹*^x5Î.

• Norm alizing the analytic signal to ¹⁷OH int ensities, standard deviat ions could be reduced by a factor of 2.

º1´xÏ µbÄ*fÐ3ÑÒÓ could be achieved for all m easured

m asses.

•^Á1 5¢^¡5¶⁷^Äx½Ôx¶^5Å5Ã*µ for Na (sea salt tracer), Al

(m ineral dust tracer) Zn and Pb (anthropogenic or contam ination tracer) are exem plarily shown in ^¹*^x

Ð. Linearity could be found for m any elem ents over the whole calibration range.

• ^{Ï £7}^£*·^Äx½¼¢^Õ^µ: Pb ⇒0.001 µg kg^-1 Na, Mg, Al, Zn ⇒0.1 – 1 µg kg^-1 Fe, Ca ⇒1 – 10 µg kg^{- 1}

•^{Ö 5¢}^¾5 7Ä1½rÄ*GÕr£7Ã*Ä3¾ by cert ified standard

reference m aterials which were prepared as norm al ice standards. Na, Mg, Al, Ca, Fe, Zn, Cd, Pb ⇒

¶£*·Ä*×3£5¶Ør 5Å5Å5¶Ä*Ù1(Úf7ÛÓ

• Optim ized ^Ä1Å*£5¶⁷½*w·Äx½*¾xÄ1½*µ are sum m arized in ^5¡5¢^£Î.

•^¹*^x¿5¶^£ÝÜ1 shows a cryogenic scanning electron m icroscopy picture of an ice surface (diam eter 300 µm ) with an ^Þº¨¢^{*µ£5¶Í·7¶}⁷^£5¶ (50 shots, 300 m J, ∅= 300 µm ).

• Along an area scan the laser beam vaporizes sm all inclusions of particles together with the surrounding ice. Such particles are exem plarily shown in ^¹3^x*Üx¡.

By m eans of a laser beam at a wavelength of 1064 nm , which was found to be m ost suitable according to the absorption coefficient of ice, m aterial from the surface is ablated. Argon is used as carrier gas.

The gas is precooled to avoid droplets at the optical window of the cell. The ablated sam ple aerosol is introduced to an I CP-MS (ELAN 6000, PerkinElm er) for subsequent ion analysis.

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Cell param et er.

Tube length to I CP 50 cm

Cell volum e 730 m L

∅optical window 10 cm Wash out tim e 7 m in

Sam ple dim ension 1 cm , 5 cm , 10 cm (h,w,d)

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Experim ent al set up.

-100°

-90°

-80°

-70°

-60°

-50°

-40°

-30°

-20°

-10°

0°

10°

20°

30°

60°

65°

70°

75°

80°

85°

NGRIP GRIP

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Opt im ized operat ing condit ions for t he I CP- MS syst em in com binat ion wit h t he I R- laser for trace elem ent analyses in frozen ice samples.

I CP- MS PerkinElem er/ Sciex ELAN 6000

RF power 1300 W

carrier gas 0.92 L m in^{- 1}

aut o lens on

isot opes m easured ¹⁷OH, ²³Na, ²⁴Mg, ²⁷Al for opt im isat ion ⁶⁴Zn, ¹⁰³Rh, ¹¹⁴Cd, ²⁰⁸Pb

laser Nd: YAG, 1064 nm

pulse m ode Q- swit ched

frequency 10 Hz

laser energy 300 mJ

spot size 300 µm

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Calibrat ion st udies wit h frozen st andard solut ions were perform ed wit h 6 t o 11 st andards ranging from 10 ngkg^{- 1}t o 100 µgkg^{- 1}.

0 1 2 3 4 5 6 7 8 9 1011

0.00 0.05 0.10 0.15

,-./

R = 0.99753 n = 11

rel. intensity*

concentration [µg kg^-1]

020406080100

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

0 20 40 60 80 100

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

0123

R = 0.99858 n = 6

rel. intensity*

0 1 2 3 4 5 6 7 8 9 1011

0.0 0.1 0.2 0.3 0.4 0.5

4567

R = 0.99909 n = 11

rel. intensity*

020406080100

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0 0.2 0.4 0.6 0.8 1.0 1.2

0.000 0.005 0.010 0.015 0.020 0.025 0.030

208Pb R = 0,99897 n = 11

rel. intensity*

020406080100

0.0 0.5 1.0 1.5 2.0 2.5

*signal intensity divided by 17OH

89:!; <= >?8:@

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Cryo- SEM pict ures of ice sam ples. 4a: I R- laser crat er, 4b: Part icles in deep- ice (1102 m ; 6209 years old) from Greenland are orient at ed at grain boundaries.

Diam et er of part icles: 3-20 µm .

H I

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Locat ions of ice coring in Greenland ( NGRI P-Nort h Greenland I ce Core Proj ect ) .

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Visible dust horizons in an ice core sam ple.

dust horizons

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Sam pling patt ern ( left ) for elem ent analyses (area scans) in ice cores by laser ablat ion. The elem ent signat ure of Al (right ) is exem plarily shown by plot t ing concent rat ion vs. sam ple lengt h. The signat ure cont ains an undulat ed progression ( m in/ m ax) which point s t o a seasonal variat ion ( wint er- - > high Al conc., sum m er- - > low Al conc.) . The annual layer t hickness ( dist ance bet ween t wo m axim a/ m inim a) is about 21.8 m m .

Pre Boreal Younger Dryas Alleröd Last Glac. Max. Post IS3 0.01

0.1 1 10 100 1000

10000 Na Al Fe Pb

10.5 12.2 13.2 24.2 26.0 element concentration in ice [µg kg-1]

sample name with estimated age [kyr before 1950]

0.01 0.1 1 10 100 1000 10000

particle concentration [µg kg-1]

Dr. Heiko Reinhardt:

Winner of A.M.S.El award 2002

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Com parison of average values obt ained by LA wit h t he m easured part icular m att er in t he respect ive geological int erval.

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Comparison of m easurem ent values for sam ple NGRI P Last Glacial Maxim um obt ained by different analyse t echniques ( values in µgkg^{- 1}) .

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• Greenland ice core sam ples (position of NGRI P, ^kml^npo

q) from different depths were analysed by LA-I CP-MS.

• ^kml^npo[rtsu^v!w^x^y shows the used sam ple pattern, a com bination of area scans (20 m m ² , no. of replicates

= 6) arranged vert ically to the core axis.

• ^kml^npo]rzs{^l^np|!x^y shows exem plarily the ^v}u^v+~v+!x

lnpm!x+{vw}{uderived of sam ple m at erial from the

u

xnpum!l+u~!}l~h+~ (depth: 1,826 m ; age:

24,200 yr before present. Al-concentration (on x-axis) is plot ted versus sam ple length. Horizontal red bars give the concentrations originating from area scans.

• An undulat ed progression (m in/ m ax) is seen within the sam ple length which points to a seasonal variation with different deposition of particulate m att er during sum m er and wint er tim e. Maxim a in elem ent concentration could also originated from dust horizons due to volcanic eruptions (^kml^npo).

• The dist ance between two m ax/ m in - the annual layer thickness - is about 21.8 m m of sam ple length.

This is in a good agreem ent with the value from the literature (21.2 m m yr^{- 1}) m easured by γ-spect roscopy.

• The vertical red line gives the average of area scans (253,8 ± 172.5 µgkg^{- 1}). The value is in a good agreem ent with the black dot ted line, the available Al- concentration (270.0 µgkg^-1; GRI P dat a) from the literature obtained by graphit e furnace atom ic absorption spectroscopy (GFAAS).

• Generally, a K}~hm+{l

}[mwu+u}~hl!{[lx|)++u++u l

is very difficult. However, to enable a com parison with conventional solut ion (bulk) analysis, average values for all m easured sam ples were calculated. These average values were com pared with dat a obtained by SN-I CP-MS, I C or literature dat a (^+++u^v).

• LA of ice sam ples enabled only a ^m+^~+++l^mn~hl^!{^+m+u ^l. Nothing is known about particles and elem ent concentration in the third dim ension. However, it could be found that the elem ent concentration obt ained by LA were in the sam e order of m agnitude as the values obt ained from the solution after tri-acid digestion.

• ^kml^npoF Sea salt and m ineral dust tracer as well as REE in Greenland ice core sam ples have shown good correlation to particle content. I t is assum ed, that these elem ents are bonded t o part iculat e m atter. No correlation was obt ained for Zn, Cd, Pb and Nd m ost probably due to contam ination or other transport processes.

• Fractionation effects could not been observed during laser ablation. This could be related to the fact, that calibration was perform ed in the sam e m atrix, however further studies will be carried out.

1axial averaged concentrations obtained by laser ablation area scans

2fraction dissolved in HNO3 3total content after tri-acid digestion HNO₃/ HF/ HClO₄ 4obtained by ion chrom atography 5com parable values from the GRIP ice core obtained by IC or GFAAS

. Analysis of ^¦^§^£«^SK¤¬¥^£¦^¢m¢^B^¥^¥^S¬¥^Pª KR^S¥ by LA- I CP- MS. Here:

2- d m apping of Ti- im plant abrasion in frozen ham st er tissues.

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• Developm ent of a new m ethod for ^x^{^mviv+uv}~v+!x+m+uv

directly from ^w^{^°Kv+hl^KviK}{^v ^+~h+u^v by ^±F^²^³F´^µ·¶

• Successfull preparation of ice st andards and quantitative determ ination of trace elem ents in real ice sam ples

• Low sam ple consum ption, quasi non-destruct ive, sam ples are available for other analytical techniques

• Reduced contam ination risk, low detection lim its

• ^m)~+++lmn[mwF¸{vmv++u}m[+vmv+mlKvi}{v (depth: < 1000 m ) sam ples with high spatial and hence

tem poral resolution has shown strong variat ions in sea salt and m ineral dust concentration owing to changes in atm ospheric transport processes in sum m er and winter t im e in the Arctic basin. Annual layers were detected also in deep-ice, which are im possible to resolve with conventional solution analysis.

• This application will be deployed for analysis of elem ent signatures in ^w^!x^+{^vg!x^+{^x^l^gl^viK}{^v

xmplv

.

• ^¹Fv!ºw^l^v}u^)l^[+l^++m+u^mx^lK+um!|mv+~hl

x{pThe new developed cryogenic ablat ion cham ber "CRYOLAC^TM"

enables the ^}m+u^l ^mww^{^°Kv} ^mw^xFx^l^K^mv ^+~h+u^v ^!h±F^²^³´^µ·¶. ^kml^npom» shows an exam ple for 2d- m apping of Titan (com ing from im plants abrasion) in frozen ham ster t issues (-45°C).

-

´}++ulK!xlp}

Reinhardt H, Kriews M, Miller H, Schrem s O, Lüdke C, Hoffm ann E, Skole J (2001) Fresen J Anal Chem , 370: 629-636.

21.8mmyr-1