biodeep wp 2 chemical characterization of seawater/brine/ sediments and related fluxes. a....

BIODEEP WP 2 Chemical characterization of seawater/brine/ sediments and related fluxes.

A. A. watercolumn/brinewatercolumn/brine analyses (UU) analyses (UU) B. B. susp.mat.susp.mat. major/minor elements; C,N (UU) major/minor elements; C,N (UU) key trace elements (Pb,Co,Zn,Cu,Cd) (UP)key trace elements (Pb,Co,Zn,Cu,Cd) (UP) C. C. sed.trapssed.traps major/minor elements; C,N (UU) major/minor elements; C,N (UU) microfossils / biogenic components (UM)microfossils / biogenic components (UM) radiotracers (radiotracers (210210Pb, Pb, 230230Th) (SOC)Th) (SOC) D. D. sedimentssediments (major/minor elements; C,N) (SOC/UU) (major/minor elements; C,N) (SOC/UU) key trace elements (Pb,Co,Cu,Zn,Cd) (UP)key trace elements (Pb,Co,Cu,Zn,Cd) (UP) E. E. pore waterpore water extraction/analysis (UU) extraction/analysis (UU)

WP2.1 CRETE-

yr2

Aspects related to brine redox chemistry

o N-speciesN-specieso S-speciesS-specieso MnMn2+2+ - MnO - MnO22 cycling cycling

o FeFe2+2+ - Fe - Fe22OO33 - Fe,S cycling - Fe,S cycling

o SOSO4 4 22 -- - HS - HS-- cycling cycling

N-species

0 1000 2000 3000 4000NH 4

+ (uM)

3600

3400

3200

3000

Dep

th (d

bar

)

- 2 0 2 4 6

NO 3- (uM)

Bannock Brine

I

II

At interface seawater/brine: nitrate jumps from 5 to 0 uM, whereas ammonia goes from ~ 0.2 to 3600 uM

In oxic seawater: org.mat. + O2 106 HCO3- + 16 NO3

- HPO42-

In anoxic brine: org.mat. + SO42- 106 HCO3- + 16 NH4+ HPO4

2- + 53 HS-

S-species: examplified by the most extreme case: URANIA Brine

0 4 8 12 16HS- (m M )

3650

3600

3550

3500

3450

3400

De

pth

(d

bar)

2 0 4 0 6 0 8 0 1 0 0 1 2 0

SO 42- (m M)

Urania Brine East

I

II

CHCH44 + SO + SO442-2- - - HCO HCO33

-- + HS + HS-- + H + H22OO

Likely dominant reaction in Urania :

BD 10C T

0 1000 2000 3000 4000

D IC (uM )

0 4 8 12 16phosphate (uM )

Atalante Basin phosphate and DIC data (BD10CT); seawater/brine interface oyxgen en sulphide data (UM08CT)

ATALANTE Basin

0 500 1000 1500 2000 2500

HS (M )

-100

0

100

200

relative Dep

th (cm

)

0 40 80 120 160 200

O 2 (M )

WP2-CTD1

1 4 1 4 . 4 1 4 . 8

Tem perature (oC)

4000

3000

2000

1000

0

De

pth

(d

ba

r)

1 2 1 6 2 0 2 4 2 8Temperature

3700

3600

3500

3400

I

II

Bannock Brine

13.6 14 14.4 14.8 15.2Tem perature (oC)

3800

3600

3400

3200

Dep

th (dba

r) I

II

Bannock.B.

Density vs depth

3400

3450

3500

3550

3600

3650

3700

3750

1.204 1.206 1.208 1.210

dens ity [g/cm3]

Bannock brines I/II (BD34CT): density and alkalinity

Alkalinity vs depth

3400

3450

3500

3550

3600

3650

3700

3750

3.8 4.0 4.2 4.4

Alk mM

Note rapid increase in alkalinity at seawater/brine I interface, and the rapid decrease at the brine I/II transition

4 0 8 0 1 2 0 1 6 0 2 0 0

Conductivity

3560

3520

3480

Dep

th (

db

ar)

I

IIAtalante B .

Orca/AB interface comparison

ATALANTE Basin

0 500 1000 1500 2000 2500

HS (M )

-100

0

100

200

relative Dep

th (cm

)

0 40 80 120 160 200

O2 (M )

2060

2120

2180

2240

2300

2360

2420

Orca/AB-2

Orca/Med.brines

Major difference in interface thickness Major difference in interface thickness

(~ 100 m vs ~ 100 cm)(~ 100 m vs ~ 100 cm)

Major difference in redox-chemistry Major difference in redox-chemistry

(Fe, S a.o.; see below)(Fe, S a.o.; see below)

Orca relative to Mediterranean brine basins:

Manganese cycling:

observations in other redox-dominated environment :

o Tyro Basin

TB

Tyro basin, eastern Mediterranean

Manganese cycling at seawater/brine Interface : (replotting data De Lange et al.)

6000

4000

2000

0

Cl (

mM

)

0 2 4 6

Mn2+ (uM)

Bannock Brineseawater interface

VV

solid 'MnO2'

dissolved 'M n2+'

Ox/Anox boundary

0 1 2 3

HS- (mmole/kg)

4000

3600

3200

2800

De

pth

(d

bar)

0 2 4 6 8 10

Mn2+ (umole/kg)

Bannock Brine

I

II

At interface seawater/brine, Mn2+ concentration jumps from ~ 0.005 to 5 umole/kg,

whereas HS- goes from 0.03 to 1800 umole/l

BB-Mn/HS

Bannock and Orca brines dissolved Fe2+, HS- (UU, Saager et al.; after Trefry et al.; Wiesenburg et al.)

0 1 2 3HS- (um ole/kg)

2400

2300

2200

2100

2000

Dep

th (

dba

r)

0 10 20 30 40

Fe2+ (um ole/kg)

Orca Brine

0 1 2 3HS- (mm ole/kg)

4000

3600

3200

2800

De

pth

(d

bar)

0 40 80 120

Fe 2+ (nm ole/kg)

Bannock Brine

I

II

(note different scales !

20020044MnMn2+2+ (uM) (uM)

0.30.33.0003.000HSHS-- (uM) (uM)

30.00030.0002020FeFe2+2+ (nM) (nM)

Bannock Orca

BBvsOB Fe,S

Major importance of: S > Mn > Fe

Brine Density Cl Na K Mg Ca SO4 B Sr Li BrAvg. m m m m m m m u u mTB 1,21 4425 4410 16 59 30 44 0,8 275 75 1BB 1,21 4430 3500 105 537 14 113 3,8 141 280 8AB 1,23 4300 3800 300 333 5,9 323 4 34 76 4DB 1,35 7030 50 15 3700 1,9 71 19 2 320 75Ube 1,13 3300 3100 108 280 28 95 9,5 410 420 8Ubw 1,13 3000 2800 90 220 34 90 9 470 440 9NB 1,2 4458 4469 4 6 15 32 4 0,3

Red S 1,2 4350 4040 56 34 120 8 0,8 550 38 2Orca 1,19 4219 3983 16 43 27 40 1Med 1,03 590 500 10 58 10 28 0,4 80 25 1

Brines average major elements

2 5

2 0

1 5

1 0

5

0

rel.

dep

th

1 000 2000 3000C l (m m ole /kg )

2 5

2 0

1 5

1 0

5

0

rel.

de

pth

1 000 2000 3000C l (m m ole /kg )

BB U B

Interface

Brine basin interfaces

450 500 550 600 650 700

Ca (ppm)

0

20000

40000

60000

80000

Na

(pp

m)

0 1000 2000 3000 4000

K (ppm )

Interface

• Conservative behaviour of Ca, Sr, K

• Diss. Mn and HS- may only be done if sampled and stored properly

Bannock basin interface

Suspended matter

• How much material in suspension

• Composition of material: major and trace elements as well as C and N concentrations

Major analytical problems because of very little sample material, and also because of extremely high salt contents of samples, …. Salt corretions are only very rough, so the results are high in error. Samples should be washed just after filtreation to remove the salt, this is vital for a reliable analysis

0.0

5.0

10.0

15.0

20.0

25.0

30.0

Atalante Uraniaeast

Discovery Bannock

susp

end

ed m

atte

r (m

g/l

)

Suspended matter

Average suspended material in different basins

Suspended matter

1062049143611506210B B

774472 33628D B

502650542556112858U B

192976444108170211A B

ppmppmppmppm mg/l 

SrSKCa  susp. matter 

Average total mass and composition

Mass and concentrations are corrected for salt influence

Suspended matter

0

10000

20000

30000

40000

50000

A B U B D B B BK

(p

pm

)

0

2000

4000

6000

8000

10000

12000

A B U B D B B B

Ca

(p

pm

)

bdl

Sediment traps

3500ST3

2500ST2

1500ST1

 Depth (m)Station BD03

 Bannock basin

Sediment traps

3500ST3

2500ST2

1500ST1

 Depth (m)Station BD03

 Bannock basin

Sediment traps

3500ST3

2500ST2

1500ST1

 Depth (m)Station BD03

 Bannock basin

3500ST4

2800ST3

1500ST2

460ST1

 Depth (m)Station PS 027

 Urania basin

Sediment traps

3500ST3

2500ST2

1500ST1

 Depth (m)Station BD03

 Bannock basin

3500ST4

2800ST3

1500ST2

460ST1

 Depth (m)Station PS 027

 Urania basin

Methodology:

• Total destruction of samples for ICP-OES and ICP-MS analysis

• Subsampling during total destruction for Si analysis with photospectrometer

• C-total, C-organic and N contents with CNS- analyser

0

1000

2000

BB oxic BB anoxic UB oxic UB anoxic

mg

/m2

/d

Total mass flux

(average september-may)

0

40

80

120

ma

teri

al f

lux

(mg

/m2 /

d)

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D

1999 2000 2001 2002

U ran ia basin ox ic 2500 m

B annock basinox ic 2500 m

0

20

40

60

80

ext

ra S

i in

sam

ple

(%

)

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D

1999 2000 2001 2002

U ran ia basin ox ic 2500 m

Bannock basinoxic 2500 m

Additional Si input in sediment: evidence for dust input

Urania Urania basin oxicbasin oxic

Bannock Bannock basin oxicbasin oxic

14,714,73,93,9average mass average mass flux (mg/m2/d)flux (mg/m2/d)

154.4353.71000.936.6134.8 anoxic

1.2 23.90.53.1 oxic

      Urania basin

24.71.073.03.218.9 anoxic

0.8 3.80.31.0 oxic

(mg/m2/d)(mg/m2/d)(µg/m2/d)(mg/m2/d)(mg/m2/d) Bannock basin

SiSMnFeCa   

Average elemental fluxes

Average chemical characterization of sediment

56,1Terr.

2,2OM

8,7SiO2 extra

33,0CaCO3

Wt%Comp.

WP2.1

Bannock anoxic

Bannock anoxic 2001/2002

2000

22002400

2600

28003000

3200

3400

36003800

4000

0 5 10 15 20

NH4+ in sediment trap bottles

Average Si-flux

autumn14%

winter11%

spring22%

summer53%

Bannock anoxic

autumn16%

winter12%

spring20%

summer52%

Average S-fluxBannock anoxic

autumn19%

winter14%

spring17%

summer50%

Average Mn-fluxBannock anoxic

Average CaCO3-fluxBannock anoxic

summer49%winter

13%

spring20%

autumn18%

Average Corg-fluxBannock anoxic

autumn15%

winter14%

spring17% summer

54%

Average N-fluxBannock anoxic

autumn13%

summer56%

winter12%

spring19%

WP2-2

Chemical characterization of Chemical characterization of sediments & pore waterssediments & pore waters

WP2.1d

Boxcore Sampling site

BW sample Winckler bottles

PW extr.

Glove-box

  water% samples

BD19MC DB x   X YES   #1

BD21MC UB.e x   X YES   #1

BD26BC AB x   X YES   #1

BD27BC normal x x        

BD31BC normal x x        

BD42BC BB x   x YES   #1

BIODEEP 2002 pore/water sampling

Chemical characterization of sediments

Sediment preparation methods Sediment preparation methods (+/- salt removal, prior to analysis; intercalibration,..)(+/- salt removal, prior to analysis; intercalibration,..)

Intercalibration Intercalibration (methods, Labs,…) (methods, Labs,…) (see Thomson)(see Thomson)

Sediment composition Sediment composition

0

5

10

15

20

25

30

0 5000 10000

DIC [umol/l]

de

pth

[cm

]

0

5

10

15

20

25

30

0 5 10

Alk [umol/l]de

pth

[cm

]

BD26BC(AB)

0

2

4

6

8

10

12

0 2 4

Dep

th (

cm)

BD26BC(AB)

Mg/Al Na/Al

0

2

4

6

8

10

12

0 20 40

Dep

th (

cm)

BD26BC(AB)

0

2

4

6

8

10

12

0 2 4

Dep

th (

cm)

Ca/Al Mn/Al

0

2

4

6

8

10

12

0 0,01 0,02

Dep

th (

cm)

0

5

10

15

20

25

30

35

0 1000 2000

HS- umol/l]

BD41BC(BB)

0

5

10

15

20

25

30

35

0 5

Alk meq/l]

0

2

4

6

8

10

12

0 2 4

Dep

th (

cm)

BD41BC(BB)

Ca/Al Mn/Al

0

2

4

6

8

10

12

0 0,02 0,04

Dep

th (

cm)

UBcores

W

E

BD07BC

BD21MC

Major differences occur between the core in E and W

basin

0

10

20

30

40

50

60

0 500

Si [umol/l]de

pth

[dba

r]

0

10

20

30

40

50

60

0 20 40

PO4 [umol/l]

dept

h [d

bar]

BD21MC(UB east)

BD21MC (UB-east)

porewater results

0 20 40 60 80 100SO 4= (m m ole/kg)

6 0

4 0

2 0

0

Dep

th (

cm)

1 2 1 6 2 0 2 4

C a (mm ole/kg)

400 440 480 520 560 600M g (mm ole/kg)

6 0

4 0

2 0

0

Dep

th (

cm)

2000 2400 2800 3200

Sr (um ole/kg)

Brine ?!

Precip. ?!

BD21MC (UB-east)

solid phase results

0 4 8 12 16 20 24

CaCO3 (wt.%)

5 0

4 0

3 0

2 0

1 0

0

Dep

ht (

cm)

0 20 40 60 80

S (wt.%)

BD07BC (UB-west) sediment results

0 2 4 6% C.tot

1 0

8

6

4

2

0

Dep

th (

cm)

0.02 0.04 0.06 0.08 0.1 0.12 0.14

% N .tot

0 4000 8000 12000 16000 20000S .tot (ppm )

1 0

8

6

4

2

0

De

pth

(cm

)

40000 80000 120000 160000 200000

N a (ppm )

3 0 4 0 5 0 6 0 7 0 8 0

Water %

Clearly for some elements the total sediment is salt-Clearly for some elements the total sediment is salt-dominateddominated

Corrections can be done from intercalibration resultsCorrections can be done from intercalibration results

UR2001 sed.

0.1 0.2 0.3 0 .4 0 .5 0.6

% C.org

6 0

5 0

4 0

3 0

2 0

1 0

0

Dep

th (

cm)

0 10 20 30% CaC O 3

0.02 0.04 0.06 0.08Ntot

0 1 2 3 4Sto t%

Sediment composition(DB)

0.1 0.2 0.3 0 .4 0 .5 0.6

% C.org

6 0

5 0

4 0

3 0

2 0

1 0

0

Dep

th (

cm)

0 10 20 30% CaC O 3

0.28 0.3 0.32 0.34K/Al

0.1 0.2 0.3Na/Al

Sediment composition(DB)

BD19MC-Cl

0

10

20

30

40

50

60

0 5000 10000

Cl [mmol/l]

0

10

20

30

40

50

60

9000 9500 10000

Cl [mmol/l]

BD19MC(DB)

WP2.1e

BD19MC

0

10

20

30

40

50

60

0 20 40

Si [umol/l]

0

10

20

30

40

50

60

0 100 200

PO4 [umol/l]

BWBW

DB-sediment

0 1000 2000 3000 4000 5000M g (m m ole /kg)

6 0

4 0

2 0

0

Dep

th (

cm)

0 0.4 0 .8 1 .2 1 .6

C a (m m ole /kg)

0 20 40 60 80S O 4= (m m ole /kg)

0 2000 4000 6000

Sr/C a (m m ole/kg)

BD19MC porewater results

4 0 6 0 8 0 1 0 0 1 2 0 1 4 0P O 4= (um ole/l)

6 0

4 0

2 0

0

Dep

th (

cm)

2 0 2 2 2 4 2 6

A lk (m eq/l)

BD19MC

DBalls

DBalls

Prelim. Composition: Ca6Mg20(SO4)6Cl13(CO32-)x. y H2O

Future Perspectives

Suspended matter (esp. at interfaces)Suspended matter (esp. at interfaces) Gas content of brines (pressure sampling!)Gas content of brines (pressure sampling!) Sediment trapsSediment traps Sediment work (Discovery basin)Sediment work (Discovery basin)