MÖSSBAUER AND CHEMICAL ANALYSES OF SOME SEDIMENTS FROM THE ROMANIAN SHORE OF THE BLACK SEA

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MÖSSBAUER AND CHEMICAL ANALYSES OF SOME SEDIMENTS FROM THE ROMANIAN

SHORE OF THE BLACK SEA

D. Barb, L. Diamandescu, M. Morariu, I. Georgescu

To cite this version:

D. Barb, L. Diamandescu, M. Morariu, I. Georgescu. MÖSSBAUER AND CHEMICAL ANALYSES

OF SOME SEDIMENTS FROM THE ROMANIAN SHORE OF THE BLACK SEA. Journal de

Physique Colloques, 1979, 40 (C2), pp.C2-445-C2-448. �10.1051/jphyscol:19792155�. �jpa-00218529�

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JOURNAL DE PHYSIQUE

Cofloque C2, supplPment au n o 3 , Tome

40,

mars 1979, page C2-445

MOSSBAUER AND CHEMICAL ANALYSES OF SOME SEDIMENTS FROM THE ROMANIAN SHORE OF THE BLACK SEA

D. Barb, L. Diamandescu, M. Morariu and 1.1. ~ e o r ~ e s c u ' NatiomZ Centre for Physics, P. 0. B. 5207, Bucharest, Romania

' P O Zytechica l I n s t i t u t e , Bucharest, Romania

X6sumd.- On a b t u d i d l l ' a i d e de l a s p e c t r o s c o p i e Mgssbauer e t p a r a n a l y s e chimique, d e s sddiments e x t r a i t s 1 d i f f L r e n t e s profondeurs ( j u s q u ' 1 1262111.) provenant du bord de l a Mer Noire a i n s i que des nodules ferromanganeux e x t r a i t s j u s q u ' l 200 m. de profondeur du fond de l a 14er Noire, c a t e roumaine.

On a m i s en Lvidence l a pr6sence de l?e3+ dans l e s nodules p r 6 l e v b s j u s q u ' l 100 m. de profondeur e t l a c o e x i s t e n c e de Fe3+ e t de Fe2+ dans l e s d c h a n t i l l o n s 1 200 m. de profondeur de l a plateforme c o n t i - n e n t a l e de l a Mer Noire. Dans l e s roches e x t r a i t e s du bord de l a mer, on a i d e n t i f i d de l ' h b m a t i t e , de l a magndtite, d e s phases amphiboles a i n s i que d ' a u t r e s oxydes e t microd16ments.

A b s t r a c t . - By means of Mgssbauer spectroscopy and chemical a n a l y s e s , sediments c o l l e c t e d a t d i f f e - r e n t d e p t h s ( t o 1262 m.) on s h o r e a s w e l l a s ferromanganese nodules t o 200 m. depth on t h e bottom of t h e Black Sea, romanian c o a s t , have been i n v e s t i g a t e d . The presence of Fe3+ i n t h e nodules t o 100 m.

depth and t h e c o e x i s t e n c e of I?e3' and Fe2+ i n t h e samples a t 200 m. depth on t h e c o n t i n e n t a l p l a t - form of t h e Black Sea were evidenced. Hematite, m a g n e t i t e , some amphiboles phases a s w e l l a s o t h e r s non-iron o x i d e s and microelements were i d e n t i f i e d i n t h e rock samples on shore a t d i f f e r e n t d e p t h s .

1 . I n t r o d u c t i o n . - One of t h e most important problems i n our days i s t o know t h e energy and raw r e s o u r c e s which a r e a v a i l a b l e a t t h e moment and i n t h e n e x t

f u t u r e . This r e q u i r e s g r e a t e f f o r t s f o r many bran- c h e s of s c i e n c e . Because of t h e abundance of i r o n

-

a s one of t h e most s i g n i f i c a n t t e r r e s t r i a l element i n many m i n e r a l phases, 5 7 ~ e fi6ssbauer spectroscopy provides u s e f u l 1 i n f o r m a t i o n i n t h i s f i e l d .

I n t h e l a s t time t h e r e was an i n c r e a s i n g in- t e r e s t i n t h e s t u d y and p o s s i b l e p r a c t i c a l a p p l i c a - t i o n s of deep-sea sediments ( e s p e c i a l l y i r o n

-

manganese nodules)/l-61. Nodules o b t a i n e d from d i f - f e r e n t l o c a t i o n s on t h e s e a f l o o r c o n t a i n widely varying p e r c e n t a g e s o f i r o n , manganese, heavy metals, some r a r e e a r t h s and r a d i o a c t i v e elements.

I n t h i s work we i n v e s t i g a t e d t h e ferrornanga- n e s e nodules from t h e bottom of t h e Black Sea t o 200 m. depth a s w e l l a s some rock samples o b t a i n e d on shore a t Constantza s i t e t o 1262 m. depth.

2. Experimental.- The analysed Black Sea sediments were taken a t t h e f o l l o w i n g depths : 60 m. ( 3 0 ~ 1 0 ' e a s t and 44O10' n o r t h ) , 90 m. (30' 22' e a s t and 44"10f n o r t h ) and 200 m.(30° e a s t and 43' n o r t h ) . Black

-

brown ferromanganese nodules of 1 - 3 cm s i z e have been c o l l e c t e d . A f t e r d r y i n g a t 105*C, t h e y were grounded i n an a g a t e mortar. The rock samples (on shore a t Constantza s i t e

-

P a l a z u Mare) were c o l l e c t e d a t t h e f o l l o w i n g depths : 585-587, 604-606, 710-720, 1262 m. For t h e Mijssbauer measu- rements t h e c o l l e c t e d samples, i n a powder form,

were uniformely d e p o s i t e d on some p l a s t i c s h e e t s . An ELRON type bgssbauer s p e c t r o m e t e r i n t h e c o n s t a n t a c c e l e r a t i o n mode was used t o g e t h e r w i t h a

10 m C i 5 7 ~ o source i n Cu m a t r i x , NaI(T1) d e t e c t o r and t h e conventional ELRON l i q u i d n i t r o g e n c r y o s t a t . The a c q u i s i t i o n of t h e d a t a was done i n a DIDAC

-

4000 I n t e r t e c h n i q u e multichannel a n a l y s e r . A l l t h e s p e c t r a were f i t t e d by means of a l e a s t square f i t - t i n g program i n t h e h y p o t h e s i s of l o r e n t z i a n shape o f Miissbauer l i n e s .

The samples were a l s o i n v e s t i g a t e d by chemi- c a l methods, n e u t r o n a c t i v a t i o n , thermogravimetric and s p e c t r a l a n a l y s e s , i n o r d e r to. e s t a b l i s h t h e chemical composition and t h e micro-elements c o n t e n t of t h e analysed sediments. The i r o n was determined by t i t r a t i o n w i t h KMnOb a f t e r r e d u c t i o n i n a Jones

t u b e w i t h metal cadmium 171.

3 . R e s u l t s . - The room temperature G s s b a u e r s p e c t r a of Fe-Mn nodules and rock samples a r e p r e s e n t e d i n f i g u r e s 1 t o 4; f i t t e d d a t a a r e c o l l e c t e d i n t a b l e s I and 111, w h i l e t h e chemical a n a l y s e s d a t a a r e in- cluded i n t a b l e s I1 and I V .

The Mgssbauer s p e c t r a of t h e nodules t o 90m.

d e p t h show a c h a r a c t e r i s t i c quadrupolar d o u b l e t of t r i v a l e n t i r o n . The l a r g e l i n e w i d t h of % 0.70 mm/s o f t h e s e d o u b l e t s can be due t o the f l u c t u a t i o n i n t h e d i s t r i b u t i o n of t h e e l e c t r i c f i e l d g r a d i e n t s .

T h i s d i s t r i b u t i o n could e x p l a i n t h e observed asymmetry of t h e d o u b l e t s . These s p e c t r a a r e charac- t e r i s t i c f o r t h e o x i d a t i o n zone of t h e Black Sea,

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792155

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JOURNAL DE PHYSIQUE

Velocity [mmls

1

F i g . 1 : Mijssbauer spectrum of Fe-& nodules from 60 m. d e p t h .

Velocity ( m m l s

1

Fig. 2 : Mijssbauer spectrum o f Fe-bln n o d u l e s from 90 m. d e p t h .

... .-

L3

. -

Velocity (mrnfsl

- -3 - 2 -1 ' .O *l + 2 * 3 ' 4 40 8 0 120 160 200 240 280 320 360 400

Chonnals Fig. 3 : M h s b a u e r spectrum of t h e sediment from

200 m. d e p t h .

The s m a l l v a l u e s of t h e isomer s h i f t s and o f t h e q u a d r u p o l a r s p l i t t i n g s prove t h a t t h e Fe v a l e n c y i s 3+ i n t h e s e combination h a v i n g t h e s t r u c t u r e o f t h e g o e t h i t e Fe203.HzO o r (Fe0OH)z. The samples a t 200 m. b e l o n g t o t h e hydrogen s u l p h i d e anoxe zone of t h e Black Sea. As i t can b e observed (Fig.3) t h i s spectrum c o n s i s t s of two q u a d r u p o l a r d o u b l e t s c h a r a c t e r i s t i c f o r ~ e ' + and F e 3 + (Table I ) .

- -

Y)

.-

S

t.

e

=

ⁿ

-

b

.- 6

.-

D

E

E S

F i g .

Channels

4 : Mijssbauer s p e c t r a of some r o c k samples from P a l a z u

-

Mare s i t e on t h e Romanian s h o r e of t h e Black Sea.

The r a t i o of F e 3 + / ~ e 2 + g 6 s s b a u e r peak a r e a s i s about 2, i n good agreement w i t h t h e q u a n t i t a t i v e d e t e n n i - n a t i o n by chemical a n a l y s e s .

T a b l e I . Room t e m p e r a t u r e MEssbauer d a t a of t h e Black Sea Fe-Mn n o d u l e s .

1 l

I

:

^{1 r o n}

Sample

:

d e p t h

:

^C.S.^(mmls) ^AEq^(mm/s) : v a l e n c y

l

I I : s t a t e s

1 l I

60 m

i

^0.30

+

0.01

i

^0.71²^0.01

i

^Fe3+

l l l

90 m

i

^0.61

+

^0.03

i

^0.77⁵^0.02

i

^Fe3+

1 I l

l l

i

^0.85²^0.01 ^2.5 ⁵^0.01

:

Fe2+

200 m

:

^I ^l

:

0 . 7

+

^{0 . 0 3} ^{0 . 8}

+

0.02

i

^Fe3'

l I 1

The Mijssbauer s p e c t r a of rock samples a t 1262 m. ( F i g . 4) a r e more complicated showing ma- g n e t i c h y p e r f i n e s p l i t t i n g s some o f them c o n s i s t i n g i n a s u p e r p o s i t i o n of s p e c t r a g i v e n by d i f f e r e n t i r o n phases. The m i n e r a l s i d e n t i f i e d by G s s b a u e r s p e c t r o s c o p y and chemical a n a l y s e s a r e p r e s e n t e d i n t a b l e s 111 and I V . One can o b s e r v e t h e h i g h amount o f FepOs i n t h e r o c k s a r 585-587 and 710-720 m.

d e p t h . By ~ Z s s b a u e r s p e c t r o s c o p y some amphibole phases were i d e n t i f i e d i n t h e r o c k samples a t 604-606 and 1262 m. The Miissbauer p a r a m e t e r s (Table 111)

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i n d i c a t e t h a t cummingtonite-grunerite and antophyl- l i t e a r e more probable phases i n our samples. By s p e c t r a l a n a l y s i s t h e following micro-elements have been i d e n t i f i e d : Pb, Sn, C r , MO, V , As, Cu, N i , CO, Zn, Ag, Ba, B. The c o n t e n t of Pb was 125 ppm a t 604-606 m. depth and 22 ppm a t 1262 m. The sample a t 605 m. depth have t h e h i g h e s t c o n t e n t of 160 ppm Cu and 50 ppm Sn. The following micro-elements were l a c k : Cd, B i , Z r , W, Ge, Nb, Be.

4. Discussions.- Concerning t h e ferromanganese no- d u l e s one has t o u n d e r l i n e t h a t i n t h e Black Sea two k i n d s of nodules with d i f f e r e n t degree of mine- r a l i z a t i o n can b e found :

a ) Phase I

-

nodules w i t h a very low degree of m i - n e r a l i z a t i o n (%3.6 P/C Fe203 and %5.5 P/C &On).

b ) Phase I1

-

nodules i n a more advanced sedimen- t a t i o n process having a high degree of m i n e r a l i - z a t i o n (%26 P/C Fez03 and 1.80 P/C MnO2).

The G s s b a u e r s p e c t r a r e p r e s e n t e d i n f i g u r e s (1-3) belong t o Phase 11; t h e s p e c t r a corresponding t o Phase I having s i m i l a r f e a t u r e s .

By comparing t h e r e s u l t s o b t a i n e d by chemical a n a l y s i s and G s s b a u e r spectroscopy on Fe-Mn nodu- l e s (Phase 1 1 ) , from t h e Black Sea w i t h those of P a c i f i c Ocean nodules (Callao

-

Peru) / l / we may conclude t h a t they a r e s i m i l a r l y r e g a r d i n g t h e i r o n and manganese c o n t e n t .

Table I1 : Chemical a n a l y s e s of t h e nodules a t 60 m depth from t h e Black Sea, Romanian shore.

Oxydes and elements Percent ( P l c )

~ 0 2 21.80

Fe203 26.00

Si02 7.60

A1203 1.21

CaO 14.35

MgO 1.50

c0 2 11.20

p205 1.92

so3

^0.03

Xa 0.19

K 0.41

T i 0.10

Cu 0.001

Ni

0.010

CO 0.003

C r 0.010

v

^0.001

M0 0.003

W 0.02

Ca3 (P0412 4.20

CaC03 21.51

MgCOs 3.14

H20 12-00

I n s o l u b l e i n HC1 9.46

Table I11 : Mijssbauer d a t a and phase d i s t r i b u t i o n of i r o n i n some rocks sampled a t Palazu-Mare on the Romanian shore of t h e Black Sea.

-8 d.-

(rtrrs)

5%-m

60s

-

⁶⁰⁶

C

&Q )

0.241

+

^0.004

0 . m O.CQ6 0.010

+

^0.014

0.19 0.016 2.74

t

0.016 1.60

+

^0.017

*n (k-) 5V.3 f 0.3

&2 ? 0.3 464

+

^0.1

p 0

+-

⁰^.¹

-

7rO

-

⁷²⁰

1262

I

1.9.

( 4 s 0.l28

+

^0.009

0.014

2

0.033 0.430

t

0.019 0.1 to.017 0.918 0.018 0 . M

2

^0.017

Identified imn phase6

-4

^{( 1 w )}^hematits

m304 (55.1%) aametite

h24

^(23.7%)^hemtib

fuwMbole (22.2%)

0.120

2

0.oob 0.028

+-

0.01) 0.475

f

0 . a 0.147 f 0.23 0.837

?:

0.02 0,861 t 0.122 0.791 f 0.W

fie% (100%) h a n n r t i ~ B 3 O 4 (49.5%)

msaetita

~ e , 4

( 4 . ~ 1 h t i t e

Amphibole (31.M)

not i d a n t i f i d 518 0.3

W ?

0.3 466

2

0.4 520 2.7

- - -

0.19

2

0.OOlr 0.0%'

+

^0.059

0.064

t

0.0%

0.189

+

0.22 2.861

+

^0.m

1 . w f o.ae 3.156

Z

0.M

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C2-448

JOURNAL DE PHYSIQUE

T a b l e I V : Chemical a n a l y s i s o f some r o c k s a t Palazu-Mare s i t e on t h e Romanian s h o r e o f t h e Black Sea.

S e e ~ P W Elementn as oxides In

(meters)

2.10,

-2%

%4 ^cao

^W ^{M O} ^%O

585-587 46.26 ^47.80 ^2.24 0.40 0.76 0.95 0.46

604

-

⁶⁰⁶ ^41.70 ^44.00 ^5.10 ^0.20 ^5.20 ^0.80 ^0.31

615

-

⁶¹⁶ ^60.26 ^28.60 ^1.98 ^1.47 ^9-70 ^1.16 ^0.14

no -

⁷²⁰ ^30.10 ^63.70 ^3.74 ^0.25 ^0.b ^0.S ^0.50

1262 42.98 41.60 5.60 0.70 5.20 1-69 0.14

They d i f f e r , however, e s s e n t i a l l y i n c o m p o s i t i o n o f t h e i r "nucleus", i . e . o f t h e i r c o r e a r r o u n d which d e p o s i t s o f F e - h a r e developed; t h e s e a r e c a l c a r e - o u s i n t h e Black Sea n o d u l e s b u t s i l i c i o u s i n t h e P a c i f i c Ocean.

Using Msssbauer s p e c t r o s c o p y i t h a s been shown t h a t up t o t h e hydrogen s u l p h i d e zone o n l y Fe3+

i s t o b e o b s e r v e d w h i l e a t t h e mixing zone o f o x i - d o - r e d u c t i o n o f t h e Black Sea Fe2+ and Fe3+ c a n b e found a s a r e s u l t o f t h e H2S r e d u c t i o n a g e n t on t h e

~ e i o n . ~ +

R e f e r e n c e s

/ l / Mero,J.L., The m i n e r a l r e s o u r c e s o f t h e s e a ( E l s e v i e r P u b l i s h i n g Comp. Amsterdam

-

London

-

New York) 1965, p.176.

/ 2 / G e o r g e s c u , I . I . , N i s t o r , C . , Rev. Roum. Phys.

11

(1970) 819.

/ 3 / Hrynkiewicz,A.Z., Putbwka,A.J., Sawicka, B.D., Sawicki,J.A., Phys. S t a t u s S o l i d i ( a )

10

(1972) 281.

/ 4 / G e o r g e s c u , I . I . , Morariu, M., Diamandescu,E., Rev. Roum. Phys.

18

(1973) 401.

/5/ Georgescu, I . I . , Barb,D., Diamandescu,L., Rapp.

Comm. I n t , Mer M6dit.

2

(1976) 37.

/ 6 / G e o r g e s c u , I . I . , Barb,D., Diamandescu, L., Mo- r a r i u , M., Demetrescu, M., Rapp. Comm. I n t . Mer M6dit.

3

(1977) 95.

/ 7 / T r e a d w e l l , F.P., H a l l , W., A n a l y t i c a l Chemistry, London (1948) 543.