35. amino acids in interstitial waters from sites 790 …€¦ · h. kawahata, t. ishizuka was <...

Taylor, B., Fujioka, K., et al., 1992Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 126

35. AMINO ACIDS IN INTERSTITIAL WATERS FROM SITES 790 AND 791IN THE IZU-BONIN ISLAND ARC1

Hodaka Kawahata2 and Toshio Ishizuka3

ABSTRACT

Sites 790 and 791 lie in the eastern half graben of the Sumisu Rift, a backarc graben west of the active Izu-Bonin arc volcanoesSumisu Jima and Tori Shima, at 30°54.96'N, 139°50.66Ti, in 2223 m water depth and 30°54.97'N, 139°52.20'E, in 2268 m waterdepth, respectively. A small decrease in the sulfate concentration in the interstitial waters from these sites suggests fairly lowmicrobial activity by sulfate-reducing bacteria.

The values of the dissolved free amino acids (DFAA) in the interstitial waters from both sites range from 1.26 to 6.82 µmol/L,with an average of 3.81 µmol/L. The acidic, basic, neutral, aromatic, and sulfur-containing amino acids have average values of0.32, 0.50, 2.71, 0.15, and 0.09 µmol/L, respectively. The relative abundances of the acidic, basic, neutral, aromatic, andsulfur-containing amino acids average 8, 13,72,4, and 1 mol%, respectively. Glycine, serine, alanine, ornithine, and aspartic acidare major constituent amino acids. The dissolved combined amino acids (DCAA) values range between 1.25 and 44.35 µmol/L,with an average of 10.36 µmol/L. The mean concentrations and relative abundances of the acidic, basic, neutral, aromatic, andsulfur-containing amino acids are 2.29 (22 mol%), 0.60 (6 mol%), 6.70 (65 mol%), 0.09 (1 mol%), and 0.00 µmol/L (0 mol%),respectively. Glycine is the most abundant amino acid residue, followed by glutamic acid, serine, and alanine. The predominanceof DCAA over DFAA present in the interstitial waters from Sites 790 and 791 is consistent with previous results frominterstitial-water and seawater analyses.

The most plausible source for the DCAA is biogenic calcareous debris. A much greater depletion of aspartic acid and the basicfraction, except for ornithine, is found in the DCAA. The decomposition of the basic amino acid fraction or its incorporation to clayminerals would result in a decrease in its relative abundance, whereas ornithine is produced during early diagenesis. The characteristicsof the amino acids in the interstitial waters are (1) a greater depletion of the acidic amino acid fraction in the DFAA than in the DCAAand (2) the enrichment of glycine and serine in both. The adsorption or reaction of the amino acids in interstitial waters with biogeniccarbonates would be responsible for the lower relative abundance of the acidic fraction of the DFAA. The production of glycine duringearly diagenesis and its stability in solution would raise its relative abundance in the interstitial waters.

INTRODUCTION

Amino acids are common to all organisms and major nitrogenouscompounds in sediments and interstitial waters (Degens, 1970; Hen-richs and Farrington, 1979). Total sediment hydrolyzable amino acidsusually decompose more rapidly than total sediment organic carbon(e.g., Whelan, 1977; Malta et al., 1982). However, the compositionof the total sediment hydrolyzable amino acids rarely changes signifi-cantly with depth (Rosenfeld, 1979; Henrichs et al., 1984). In contrast,both the concentration and composition of the dissolved free aminoacids (DFAA) change markedly with depth (Henrichs and Farrington,1979; J0rgensen et al, 1981; Henrichs et al., 1984). This differencereflects the differing time scale of supply and removal: tens of yearsor more for total sediment organic carbon and total sediment hydro-lyzable amino acid, but less than one day for DFAA (Christensen andBlackburn, 1980).

Because the amino acid concentrations in interstitial waters aremuch lower than those in sediments, even small changes of the latterwould lead to large changes of the former. Thus, the dissolvedcombined amino acids (DCAA) in interstitial waters as well as theDFAA seem to be sensitive and important indicators of early diagene-sis. However, little work on this subject, particularly on DCAA ininterstitial waters, has been done (Ishizuka et al., 1988; Kawahata andIshizuka, 1989; Kawahata et al., 1990; Ishizuka et al., 1990). There-fore, this paper presents the results of the DFAA, DCAA, and totalhydrolyzable amino acids (THAA) in interstitial waters collected

Taylor, B., Fujioka, K., et al., 1992. Proc. ODP, Sci. Results, 126: College Station,TX (Ocean Drilling Program).

2 Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki 305, Japan.3 Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo

164, Japan.

during Ocean Drilling Program (ODP) Leg 126 and discusses theircharacteristics and the relationship among them.

METHODS

Sampling and Storage

Interstitial waters from the sediments at Sites 790 and 791 werecollected aboard JO1DES Resolution by hydraulic squeezing. Allinterstitial-water samples were filtered through 0.22-µm Milleporecellulose acetate filters in the shipboard laboratory. For amino acidanalysis of the interstitial water, a 5-mL aliquot of the water samplewas placed in a precombusted glass ampule. After being flushed withhelium, the ampule was sealed and stored refrigerated (1°-2°C) untildelivery to the land-based laboratory.

Analytical Procedures: Amino Acids

The DFAA in the interstitial waters were analyzed after the addi-tion of 7 µL of ultrapure (amino-acid-free) 17% HC1 to 0.7 mL of aninterstitial-water sample. Amino acid concentrations were determinedby direct injection of the sample into an automated liquid chroma-tograph (Hitachi model 835). The reported concentrations have beencorrected for the reagent blank.

For total hydrolyzable amino acids (THAA), 1 mL of interstitialwater, together with 1 mL of ultrapure concentrated HC1 to adjust thesolution to 6N HC1, was placed in a precombusted glass ampule andhydrolyzed at 110°C for 22 hr under an argon atmosphere. Then, thesolution was evaporated gently using a rotary evaporator at a tem-perature lower than 42°C and the residue was redissolved in 1 mL of0.01 mol HC1. This aliquot was injected into the amino acid analyzer.The standard deviation for amino acid analysis based on replicatedmeasurements of a standard solution (about 1 µmol/L for amino acids)

531

H. KAWAHATA, T. ISHIZUKA

was < 10%, and the detection limit of our method was about 0.05 µmol/L.Low values of DFAA and THAA near the detection limit may not bedependable. Nevertheless, we retain these values because they confirmthat the amino acid concentration is low (Ishizuka et al., 1988).

SUMMARY OF THE GEOLOGICAL FRAMEWORK

Sites 790 and 791 lie in the eastern half graben of the Sumisu Rift,a backarc graben west of the active Izu-Bonin arc volcanoes SumisuJima and Tori Shima (Fig. 1). Site 791 was drilled on the western edgeof the flat basin floor of the graben, whereas Site 790 is situated on aslight rise and structural high to the west of the flat basin floor. Thesites are 2.4 km apart.

Site 790 is at 30°54.96'N, 139°50.66'E, at 2223 m below sea level(mbsl). The stratigraphic succession consists of three lithologic unitscomposed predominantly of volcanogenic materials; the upper two unitsare sedimentary, whereas the basal unit is igneous. The sedimentary unitsalso contain variable quantities of biogenic materials, mainly nannofos-sils (Table 1). Site 791 is at 30°54.97'N, 139°52.20'E, at 2268 mbsl. Thesuccession is divided into three lithologic units; the upper two units aresedimentary and the lower one is igneous (Table 1).

Sedimentation rates determined from calcareous nannofossil andradiolarian datums and from paleomagnetic events at each site exhibit anexponential increase over the recovered interval. At Site 791, sedimenta-tion rates increase from 344 m/m.y. at the base of Unit II (approximately1 Ma) to more than 2200 m/m.y. at the top of Unit I. At Site 790,sedimentation rates increase from 90 m/m.y. at about 1 Ma to about1000 m/m.y. at present. Before 0.275 Ma, sedimentation rates at Site 791are approximately 4 times those found at Site 790. Between 0.275 and0.10 Ma, linear sedimentation rates at Site 791 are greater by a factor of3 (Table 1) (Shipboard Scientific Party, 1990).

Average total organic carbon (TOC) and inorganic carbon (carbonate)are 0.40 and 1.85 wt% (15.4 wt%) at Site 790 and 0.45 and 2.24 wt%(18.6 wt%) at Site 791 (Shipboard Scientific Party, 1990).

INORGANIC CHEMISTRY OF THE INTERSTITIALWATERS

The chlorinity and pH are about 514 mmol/L and 7.57, respec-tively, and are fairly constant throughout the holes drilled at Site 790.The concentrations of sulfate decrease gradually from 27.9 to 15.1mmol/L in the upper 200 m and increase to 22.9 mmol/L at the bottom,which suggests low activity of sulfate-reducing bacteria. The profileof calcium is similar to that of sulfate. Average concentrations ofcalcium, magnesium, ammonium, and silica are 9.2 µmol/L, 52.4mmol/L, 754 µmol/L, and 699 µmol/L, respectively.

Chlorinity, pH, and sulfate concentration are fairly constantthroughout the holes of Site 791. Their mean values are 565 mmol/L,7.60, and 27.2 mmol/L, respectively. The calcium concentration is atabout 20 mmol/L in the upper 40 m, and it decreases abruptly to about10 mmol/L between 40 and 200 m below seafloor (mbsf) and gradu-ally increases below this depth. Magnesium concentration vs. sub-bottom depth shows a reversed profile of the calcium concentration.The Mg concentration is about 45 mmol/L in the upper 40 m, increasesabruptly to about 53 mmol/L between 40 and 200 mbsf, and decreasesgradually below this depth. The average concentrations of ammoniumand silica are 363 and 543 µmol/L, respectively (Shipboard ScientificParty, 1990).

RESULTS

Site 790

The concentrations of THAA in the interstitial waters are given inTable 2 and are plotted vs. sub-bottom depth in Figure 2. The THAAvalues range between 3.53 and 19.36 µmol/L and average 8.18µmol/L. Neutral amino acids are the most abundant fraction of the

35" N

30" N

• . ^ M i y a k e J i m a

•%^ * II a c h i j o J i • a

Aoga Sh i•a

7 9 0 / 7 9 1

U 0 " E

Figure 1. Location of Sites 790 and 791.

amino acids and account for 62% of the total THAA. The averageconcentration is 5.10 µmol/L. The second most abundant fraction isthe acidic amino acids. The mean concentration is 1.68 µmol/L, whichconstitutes 21 mol% of the total THAA. The basic amino acid fractionis 0.72 µmol/L on average, which accounts for 9% of the total THAA.The aromatic and sulfur-containing amino acids are minor fractions.Their mean values are 0.11 and 0.09 µmol/L, respectively. The relativeabundances of aromatic and sulfur-containing amino acids are eachonly 1 mol% of the total THAA. The THAA composition shows noconsistent trend with sub-bottom depth or with the total concentration.Glycine is the most abundant amino acid residue, with glutamic acid,serine, and ornithine next. The f and α-amino butyric acids andß-alanine of nonprotein amino acids constitute about 2,1, and 1 mol%of the total THAA, respectively.

The DFAA concentrations in the interstitial waters are given inTable 3 and Figure 3 and are plotted vs. sub-bottom depth in Figure2. Total DFAA values range from 1.26 to 6.82 µmol/L and average3.41 µmol/L. Average values of the acidic, basic, neutral, aromatic,and sulfur-containing amino acids are 0.32,0.40,2.50,0.07, and 0.09µmol/L, respectively. The relative abundances of acidic, basic, neu-tral, and aromatic amino acids average 9, 12, 73, 12, and 2 mol%,respectively. Glycine, serine, alanine, and ornithine are major aminoacids of DFAA. The DFAA shows that the profile is similar to that ofTHAA. Relatively high concentration values are found at the nearsurface (131 and 255 mbsf), which do not always correspond to highvalues of TOC and CaCO3 in the sediments.

532

AMINO ACIDS, SITES 790 AND 791

Table 1. Characteristics of lithologic units, Sites 790 and 791.

UnitDepth(mbsf) Lithology Age

Porosity Density(g/cm*)

Sedimentationrate

(m/m.y.)

Site 790I 0-165 Vitric silt, vitric sand, pum- Quaternary 67 2.6 717

iceous gravel, clayey silt,and silty clay. Gravels arefelsic; sands are mafic andfelsic. Triplet beds ofblack sand/silt, light grayvitric clayey silt, and bur-rowed clayey silt withpumice and basalticgrains.

165-266.6 Nannofossil clay, nannofossil- Quaternary 66 2.7 131rich clay, silty clay, andclayey silt. Thin ash beds.Scattered pumice and sco-ria clasts. Triplet bedsfrom 165 to 184 mbsf asin Unit I.

266.6-387 Scoriaceous basalt. Quaternary - - -

0-428.4 Pumiceous gravel, pumiceous Quaternary 66 2.5 1930pebbly sand and sand,vitric silt with minor clay,silty clay, and nannofossil-rich silty clay.

428.4-834 Nannofossil-rich claystone Quaternary 59 2.7 522and nannofossil claystonewith scattered volcanicgrains, particularly below680 mbsf; nannofossilsandy mudstone; andvitric silt. Pyrite occurs inburrows.

834-1145 Basalt, diabase, basaltic Quaternary - - -mousse, felsic ash tolapilli tuff, and rare darkvitric silt.

Note: Mean values from Shipboard Scientific Party (1990).

πi

Site 7911

πi

Hydrolyzable Free

Relative abundance Total (µM/L) Relative abundance Total (µM/L)

0 10 20 30 40 50 60 70 80 90 100 0 10 20 0 10 20 30 40 50 60 70 80 90 100 0 2 4 6 8 10

Figure 2. Concentrations of acidic, basic, neutral, and total amino acids of THAAand DFAAin interstitial waters vs. depth, Site 790.

Site 791

Concentrations of individual THAA are given in Table 2. Total

concentrations of THAA range from 6.02 to 49.94 µmol/L and

average 20.16 µmol/L. In a plot of THAA concentrations vs. sub-

bottom depth (Fig. 4), total THAA values generally decrease vs.

sub-bottom depth. In contrast, the contents of CaCO3 in the sedi-

ments generally increase vs. sub-bottom depth. Fairly high values

are found at depths of 38 and 137 mbsf. In spite of the high

fluctuation of the total THAA values, the relative abundance of the

individual amino acids is fairly uniform throughout the holes. The

mean values of the acidic, basic, neutral, aromatic, and sulfur-con-

taining amino acids are 3.55, 1.49, 13.74, 0.37, and 0.09 µmol/L,

respectively. Their mean relative abundances are 18, 7, 68, 2, and

0.4 mol%, respectively.

Concentrations of individual DFAA given in Table 3 are plotted

vs. sub-bottom depth in Figure 4. Total DFAA concentrations range

from 1.74 to 5.83 µmol/L and average 4.21 µmol/L. Fairly high values

are found in the upper 150 m and at 813 mbsf. The mean values of

acidic, basic, neutral, aromatic, and sulfur-containing amino acids are

533


Table 2. Concentrations in µmol/L of total hydrolyzable amino acids (THAA) in interstitial waters, Sites 790 and 791.

Hole, core, sectionInterval (cm)

Depth (mbsf)

AcidicAspartic acidGlutamic acid

BasicOmithineLysineHistidineArginine

INcutriilHydroxy

ThreonineSerine

StraightGlycineAlanine

BranchValineIso-leucineLeucine

OtherAspargine

AromaticTyrosinePhenylalanine

SulfurCysteinMethionine

OtherTaurineCitrullineα-aminoadipic acidα-aminobutyric acidß-aminobutyric acid7-aminobutyric acidß-alanine

Total

790B-2H-3140-150

13.25

0.390.84

0.34——0.07

0.490.78

1.560.96

0.360.270.19

_

0.08

0.02

———0.13—6.48

79OB-3H-5140-150

25.75

0.291.69

0.18—0.08—

0.130.10

0.620.25

0.300.190.17

_

0.080.02

0.220.08———

0.080.545.00

790B-6H-3140-150

46.95

0.190.76

0.38—

—

0.090.59

0.700.21

0.260.180.11

_

————

0.073.53

790B-8H-5140-150

69.05

0.531.01

0.440.03

-

0.611.23

2.381.22

0.440.280.25

0.15

0.03

_

—0.24

8.83

790B-9H-2140-150

74.25

0.290.80

0.480.03

—

0.100.73

1.690.38

0.250.190.14

0.11

—

0.240.095.51

790C-2H-50-5

100.45

0.541.37

0.770.08

0.02

0.282.01

3.370.87

0.230.230.21

0.05

0 1 1

_

—0.120.07

10.33

790C- 5H-5140-150

130.95

0.541.78

0.580.030.040.03

0.481.74

2.981.15

_0.290.26

_

0.21

0.02

—

—0.090.07

10.30

790C-I0H-1101—111

165.96

0.330.79

0.230.14

0.06

0.460.19

1.181.34

0.510.210.21

_

0.05

0.03

———0.250.106.08

790C-13H-3140-150

196.85

0.420.70

0.480.O4

0.08

0.330.53

1.670.82

0.190.18

0.06

0.02

—0.350.126.00

790C-16H-3140-150

227.25

0.511.07

0.800.05

0.13

0.411.11

2.360.99

0.240.21

0.18

0.03

———0.370.108.57

30 -

20 -\

10 -

7 9 0 1

7 9 0 II

7 9 1 1

7 9 1 π

CM

CO

< u

z06

O

to to-

a

u05

<

06

as05

w00

<

>

w•J

_

3

Figure 3. Composition of DFAA in interstitial waters, Sites 790 and 791. The mean mole percentage of each amino acidfrom all lithologic units at both sites is plotted. Asp = aspartic acid, Glu = glutamic acid, Orn = ornithine, Lys = lysine,His = histidine, Arg = arginine, Thr = threonine, Ser = serine, Gly = glycine, Ala = alanine, Val = valine, He = iso-leucine,Leu = leucine, Tyr = tyrosine, Phe = phenylalanine, Cys = cysteine, and Met = methionine.

0.33,0.61, 2.93, 0.23, 0.08 µmol/L, respectively. Their mean relativeabundances are 8, 14, 70, 6, and 2 mol%, respectively.

DISCUSSION

DCAA in Interstitial Waters

Amino acids are present in free and combined states in the inter-stitial waters. The concentration of DCAA can be calculated by

subtracting the DFAA concentration from the THAA concentration inthe interstitial waters from Sites 790 and 791 (Table 4 and Fig. 5). Therespective concentrations of DCAA and DFAA are, on average, 4.1and 3.0 µmol/L in lithologic Unit I and 5.9 and 4.1 µmol/L in Unit IIat Site 790 and 22.4 and 4.6 µmol/L in Unit I and 4.6 and 3.5 µmol/Lin Unit II at Site 791. The results show a predominance of DCAA overDFAA in the interstitial waters at Sites 790 and 791, which is consis-tent with previous results from interstitial-water and seawater studies

534


Table 2 (continued).

79OC-18H-2140-150

254.65

1.162.50

1.190.45

(1.24

1.071.41

4.222.07

0.7K0.320.56

0.21

0.95

79IA-2H-5140-150

11.95

0.571.50

0.820.300.240.12

0.423.60

1.930.66

0.200.000.23

0.120.03

0.92

79IA-5H-3140-150

37.45

2.088.13

3.460.751.010.31

1.788.67

14.903.79

1.330.801.07

0.45

79IA-9H-6140-150

80.25

1.002.84

0.960.380.190.25

0.613.25

10.121.51

0.4?0.240.54

0.29

79IA-12H-5140-150

107.85

0.841.87

-

1.386.33

8.172.87

0.930.360.41

0.26

79IA-I5H-625-35

137.30

1.755.38

2.030.470.660.00

1.025.00

12.022.56

0.950.570.80

0.39

791A-18H-690-100

166.95

0.821.93

0.260.240.200.18

0.352.10

10.450.81

0.140.070.40

0.29

791A-22H-6140-150

205.85

1.042.27

0.340.370.310.33

0.432.75

13.481.00

0.150.070.49

0.33

79IB-I0R-186-96

474.21

0.331.23

0.190.120.090.20

0.240.73

3.460.53

0.050.18

0.20

791B-13R-1140-150

503.55

0.541.37

0.240.170.16

0.421.08

3.820.68

0.08

1.060.21

791B-23R-3115-125

602.90

0.401.16

0.030.13

0.310.39

1.720.77

0.15

0.20

0.010.28

_

79IB-45R-2140-150

813.20

0.401.57

0.570.160.13

0.200.74

1.770.74

0.300.130.22

0.18

_

0.30

1.20

0.37 0.04

0.07

0.07

0.03

0.070.190.06

19.36

0.13

11.850.99

49.94

—3.40

26.24

—0.29

24.020.43

34.430.74

19.020.38

23.93

0.05

0.508.08

0.4110.24

0.286.02

0.808.04

Hydrolyzable Free

Relative abundance Total (µM/L) Relative abundance Total (µM/L)

0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 0 2 4 6 8

0 -

100-

200-i

jr 300-

ε= 400-*_>a.α>

° 500-

600-

700-

800-

i

;

i

r1

j

Å

i

Figure 4. Concentrations of acidic, basic, neutral, and total amino acids of THAA and DFAA in interstitial waters vs. depth, Site 791.

535


Table 3. Concentrations in µmol/L of dissolved free amino acids (DFAA) in interstitial waters, Sites 790 and 791.

Hole, core, sectionInterval (cm)

Depth (mbsf)


BasicOrnithineLysineHistidineArginine

NeutralHydroxy

ThreonineSerine

StraightGlycineAlaniπe


OtherAspargine


SulfurCy steinMethionine

OtherTaurineCitrullineα-aminoadipic acidα-aminobutyric acidß-aminobutyric acidv-aminobutyric acidp-alanine

Total

790A-2H-3140-150

13.25

0.160.06

0.22—

0.00

0.180.75

0.760.32

0.090.080.19

_

0.04—

0.02

0.00

—————2.88

790A-3H-5140-150

25.75

0.130.14

0.080.00

0.110.10

0.230.14

0.300.06—

0.02

0.200.08

——1.59

790B-6H-3140-150

46.95

0.16

0.36

0.090.59

0.640.21

_

0.080.11

—0.042.28

79OB-8H-5140-150

69.05

0.13

0.23

0.160.60

0.690.29

0.260.090.20

0.03

——2.70

790B-9H-2140-150

74.25

0.230.11

0.380.03

0.100.73

0.730.31

0.130.190.14

0.11

——3.19

790C-2H-50-5

100.45

0.180.03

0.220.08

0.02

0.180.66

0.520.27

0.230.210.04

0.02

——2.68

790C-5H-5140-150

130.95

0.340.11

0.35

0.04

0.341.49

1.640.70

_

0.290.26

0.13

——0.035.76

790C-10H-1101-111

165.96

0.090.11

0.13

0.03

0.080.19

0.250.13

0.11

—

0.05

——0.091.26

79OC-I3H-2140-150

196.85

0.200.11

0.320.04

0.150.49

0.460.29

_

0.070.18

———2.31

790C-16H-3140-150

227.25

0.500.19

0.80

0.411.11

1.490.85

_

0.240.21

0.15

———6.01

a.00

<

2Xo

00

>

J

00

__

se

oX<

X—H

X

a00 O

<

- j

<

<

>

a

-W

J

X

>

00

>

αEd

S

Figure 5. Composition of DCAA in interstitial waters, Sites 790 and 791. The mean mole percentage of each amino acidfrom all lithologic units in both sites is plotted. See Figure 3 for an explanation of abbreviations.

(Siegel and Degens, 1966; Kawahata and Ishizuka, 1989; Lee andBada, 1975). The mean values and relative abundances of acidic,basic, neutral, aromatic, and sulfur-containing amino acids are 2.29(22 mol%), 0.60 (6 mol%), 6.70 (65 mol%), 0.09 (1 mol%), and 0.00µmol/L (0 mol%), respectively.

Smear slide observations indicate that the major constituents ofthe sediments from Sites 790 and 791 are volcanic glass, feldspar,clays, and calcareous nannofossils. The high sedimentation rate atSites 790 and 791 is a result of the large input of volcanic glass to thesediments. Glass and feldspar lack organic material. The geographic

and geologic situation of both sites eliminates the possibility of amajor contribution of land-derived amino acids. Thus, the amino acidsin the interstitial waters originate from those of calcareous biogenicdebris, with lesser amounts of siliceous debris.

One of the important characteristics of the relationship between theamino acids of the source material and the DCAA is that aspartic acidand the basic fraction, except for ornithine, are much more depleted inDCAA (Figs. 5 and 6 and Table 5). On the other hand, the charac-teristics of the amino acids in the interstitial waters indicate a greaterdepletion of the acidic amino acid fraction in the DFAA than in the

536



79OC-I8H-2140-150

254.65

0.290.19

0.450.160.270.04

0.291.29

1.140.72

0.210.320 27

0.21

0.95

791A-2H-5140-150

11.95

0.290.11

0.620.18

0.301.38

1.040.54

0.11

0.19

0.100.03

0.92

791A-5H-3140-150

37.45

0.300.10

0.810.180.32

0.291.46

0.97

0.15

0.17

0.45

79IA-9H-6140-150

80.25

0.250.15

0.450 240.19

0.321.33

1.040.54

0.250.240.22

0.21

791A-I2H-5140-150

107.85

0.320.1 3

0.401.78

1.380.65

0.230.310.25

0.04

79IA-I5H-625-35

137.30

0.24

0.490.150.22

0.271.26

1.090.54

0.220.330.25

0.24

791A-I8H-690-1 (X)

166.95

0.090.04

0.260.000.160.00

0.090.24

0.230.15

0.010.17

0.29

791A-22H-6140-150

205.85

0.120.00

0.320.060.180.07

0.140.46

0.480.25

0.120.070.15

0.33

791B-I0R-I86-96

474.21

0.190.05

0.190.100.090.01

0.180.73

0.760.45

0.050.18

0.20

791B-13R-1140-150

503.55

0.170.04

0.240.000.13

0.130.49

0.620.36

0.08

0.21

791B-23R-3115-125

602.90

0.270.16

0.030.11

0.190.39

0.680.54

0.15

0.20

0.010.28

791B-45R-2140-150

813.20

0.370.24

0.570.160.13

0.200.74

1.340.74

0.300.130.22

0.18

•: 0.07

0 105.59 5.49 5.35

0.012.75 3.17 2.47 3.09

~ 30 -

c° 2 0 -J

to0aεou io -

F o r a • i n i f e r s

D i ato•s

Sponges

PM

<

J

U

zao

C/3 CO

> -

U

<

X

- W

or)

>-

U

<

<

- j

<

> — H S-

Figure 6. Amino acid composition of foraminifers, diatoms, and sponges plotted for comparison with DCAA and DFAA.See Figure 3 for an explanation of abbreviations.

DCAA and an enrichment of glycine and serine in both. The adsorptionor reaction of the amino acids in the interstitial waters with biogeniccarbonates would be responsible for the lower relative abundance of theacidic fraction of the DFAA than the DCAA (Kawahata and Ishizuka,1989). Glycine is possibly derived from serine, threonine, valine,tyrosine, and histidine by decomposition from heating (Terashima andInouchi, 1990). In addition, it has the simplest structure of the proteinamino acids and a greater advantage in its stability in solution than theother amino acids that have a more complicated structure, which wouldraise its relative abundance in interstitial waters.

Biogeochemical Characteristics of Minor ConstituentAmino Acids in Interstitial Waters

Information on the nature of the amino acids in the interstitialwaters can be obtained from the distribution of minor constituents.Especially significant in this regard is the presence of nonproteinamino acids, about 10 mol% of the total DCAA.

The mean relative abundances of ß-alanine and y•amino butyricamino acid are about 4 and 1 mol% of the total DCAA at Sites 790and 791, respectively, whereas neither is found in DFAA. Although

537


Table 4. Concentrations in µmol/L of dissolved combined amino acids (DCAA) in interstitial waters, Sites 790 and 791.

Hole, core.section

Interval (cm)

Depth (mbsf)



NeutralHydroxy

ThreonineSerine



OtherAspargine

AromaticTyrosinePhenyl alanine

SulfurCysteinMethionine

OtherTaurineCitrullineα-aminoadipic acidα-aminobutyric acidß-amino iso-butyric acidY-aminobutyric acidp-alanine

Total

790A-2H-3140-150

13.25

0.230.78

0.12

—

0.07

0.310.03

0.790.64

0.270.19

—

0.03—

———

0.130.003.6*1

790A-3H-5140-150

25.75

0.161.55

0.18

—

—

0.02

0.190.11

0.120.17

—

0.08—

0.020.01———o.ox0.543.42

790B-6H-3140-150

46.95

0.020.76

0.02

—

—

0.06

0.260.10

—

—

———

0.031.25

790B-8H-5140-150

69.05

0.401.01

0.21—

—

0.450.64

1.690.93

0.180.200.05

—

0.15—

———

0.24

6.13

790B-9H-2140-150

74.25

0.060.70

0.10—

—

0.960.07

0.12

—

—

—

———0.240.092.32

790C-2H-50-5

100.45

0.361.34

0.55—

—

0.101.35

2.840.60

——0.17

—

0.05—

—

0.09

———

0.120 077.65

79OC-5H-5140-150

130.95

0.201.66

0.24—

0.03

0.150.25

1.340.45

——

—

0.08—

—

0.02

———

0.090.044.54

79OC-I0H-I101-111

165.%

0.240.68

0.100.14

0.03

0.38—

0.931.21

0.390.210.21

—

O.(X)—

——

0.03————0.250.024.82

79OC-13H-2140-150

196.85

0.220.59

0.16—

0.08

0.180.04

1.210.53

—0.12—

—

0.06—

——

0.02————0.350.123.69

790C-I6H-3140-150

227.25

0.010.88

—

—

0.13

——

0.870.15

———

—

0.03—

——

0.03————0.370.102.56

ß-alanine and y•amino butyric amino acid are generally thought to bedecomposition products of aspartic and glutamic acids, respectively,there was no evidence for their production during studies on eitherultracleaned foraminifer tests or various proteins in buffered solution(Schroeder, 1975). Thus, it appears that their common presence insediments from the natural environment is related to the enzymaticdecomposition of aspartic and glutamic acids (Ittekkot et al., 1984b).Such decomposition can take place either on particles (Lee andCronin, 1982) or in the guts of organisms (Ittekot et al., 1984b).Jannasch et al. (1971) suggested that microbial degradation is slowin the deep-sea environment, and Wafer et al. (1982) showed that mostof the degradation of polypeptides takes place at depths above 1000 mand fha.t flux changes below this depth are much slower. However, ingeneral the relative abundance of nonprotein amino acids collected insediment traps is fairly low (



790C-18H-2

140-150

254.65

0.872.31

0.730.2')0.220.20

0,780.11

3. OX1.35

0.570.010.30

79IA-2H-5140-150

1 1.9.5

0.281.38

0.210.120.240.12

0.122 22

0.880.11

o.


Table 5. Amino acid composition of interstitial waters from Sites 790 and 791, particulate matter, and marine plankton.



NeutralHydroxy

ThreonineSerine



OtherAspargine


SulfurCysteineMethionine

OtherTaurineCitrullineCystathionineß-alanineα-amino butyric acidß-amino iso-butyric acidY-amino butyric acidα-amino adipic acid

Total

Site 790

(µM)

0.220.10

0.310.040.040.01

0.190.73

0.780.38

0.120.150.15

0.040.02

0.09

0.020.01

————

0.013.41

(molr/rl

9.36.52.8

1 1.69.21.11.00.2

73.3

5.621.4

22.811.3

3.64.44.3

1.91.30.62.62.6

1.30.70.2

—————

100

DFAA

S

(µM)

0.240.09

0.360.110.130.01

0.230.93

0,880.43

0.150.140.18

0.010.22

0.08

0.01

————

0.014.21

Interstitial

ite 791

(molr/r)

7.85.62 2

14.48.62.63.10.2

69.7

5.422.1

20.810.3

3.53 24 J

5 50.25.32.02.0

0.50.3

——

—0.2

100

waters

Site 790

(µM)

0.251.1 1

0.220.040.020.5

0.210.22

1.290.55

0.160.090.08

0.04

0.04

0.100.1 1

0.19—

4.78

(molr/f)

28.65.3

25 36.84.60.80.41.0

54.6

4.54.6

27.11 1,5

3,41,81,7

0.90.9

9.10.8

2.12.3

—4.0

—100

DCAA

Site 791

(µM)

0.652.57

0.450.170.140.12

0.422 22

6.561.01

0.280.080.23

0.100.04

0.1 1

0.74—0.050.01—

15.95

(molr/f)

20.24.1

16.15 52.81.10.90.7

67.8

2.613.9

41.26.4

1.70.51.4

0.9

0.3

5.70.7

4.6—

0.30.1

—100

Particulate matter

Marine41

25.316.78.6

14.50.18.61.93.9

51.6

5.07.2

17.99.6

5.02.54.4

5.22 52.7—

1.4

0.9——0.5—

98.0

River11

24.913.11 1.8

3.00.92.1

61.2

4.06.7

18.314.8

6.23.08.3

3.50.82.70.3

0.3—

——————

93.0

Forzirπiπifcrs1'

40.7

13.86.0

1.71.52.8

44.2

3.73.2

16.77.8

6.33.03.5

0.60.10.50.3

0.3—

——————

91.8

Diütoms''

24.113.210.92.3

0.51.60.2

61.2

8.2

11.6

1 1.510.5

6.04 39.1

—5.32.13.22.6

2.6—

——————

95.5

Sponges1

20.612.38.38.2

4.01.23.0

54.9

4.710.2

13.49.4

6.24.07.0

—4.82.42.40.8

0.8—

——————

89.3

R 3d i o lsπ iiπ s

28.315.612.78.30.93.9

3.358.1

4.46.3

22.79.0

7.12.75.9

—4.51 5

0.5—0.5——

——————

99.7

Note: — = not reported.

"I t tekkoteta l . (1984a. 1984b).b P e a k e e t a l . (1972).c Degeπs(1970) .d K i n g ( 1 9 7 4 ) .

540

35. amino acids in interstitial waters from sites 790 …€¦ · h. kawahata, t. ishizuka was <...

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