SEAWATER
Saturated
§ill
Monounsaturated 20 -- - - - -- - -- --- - -- - - --- - --- - -- -II Branched -
- - --10
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Chain Length
Fig. 15 Fatty acid compositions of Samples D916 and D921.
l'abk-+ I at!\ :Jc1d compositions 111 the sediment samples of the 1\onh Knnll Ihc\'a R1d � 'L'
D8S7R D857B 01030
Fatt� acH.b }A gig \\'l. '* ]A gig wt.Sf }A gig \\l. rx
9:0 0.13 0.�
I 0:0 0.07 0.44
11:0 0.05 0.32
1::2:0 ::2.75 O.Tl 5.43 0.46 0.48 3.()()
i13:0 0.15 0.04 0.47 0.04 0.07 0.45
ail3:0 0.17 0.05 0.50 0.04 0.03 0.19
13:0 0.41 0.11 0.97 0.08 0.13 0.86
brl4:0 3.18 0.89 8.52 0.72 0.55 3.54
14:0 11.3::2 3.17 41.97 3.55 1.03 6.56
i15:0 1.71 0.48 3.79 0.32 0.20 1.31
ail5:0 ::2.80 0.78 7.5R, 0.64 0.33 2.07
15:0 6.48 1.81 19.47 1.65 0.41 2.61
brl6:0 0.2.5 1.60
16:1 1.88 0.52 4.31 0.36
16:1�7 15.35 4.29 175.01 14.82 0.13 0.81
16:1�9 0.00 0.00 55.14 4.67 0.29 1.84
16:0 114.97 32.16 430.02 36.42 3.19 20.37
br17:0 5.47 1.53 7.33 0.62 0.10 0.66
il7:0 1.24 0.35 0.62 0.05 0.08 0.50
ai17:0 2.90 0.81 4.36 0.37 0.16 1.05
17:1 0.00 0.00 2.60 0.22 0.07 0.44
17:0 6.97 1.95 12.88 1.09 0.35 2.25
18:3 8.63 0.73 0.06 0.38
18:2 5.14 1.44
18:1.m 26.26 734 46.23 3.92 0.40 2.54
18:1�11 5.25 1. 47 55.18 4.67 0.14 0.92
18:0 48.85 13.66 178.63 15.13 1.78 11.38
19:1 0.04 0.26
19:0 5.67 1.59 7.62 0.65 0.33 2.12
20:1 0.11 0.71
20:0 7.35 2.06 16.18 1.37 0.63 4.01
21:0 10.26 2Jr7 4.94 0.42 0.27 1.75
br22:0 8.41 2.35 11.97 1.01
22:0 16.23 4.54 38.95 330 0.83 5.30
23:0 13.54 3.79 5.99 0.51 0.23 1.50
24:0 10.90 3.05 13.07 1.11 1.01 6.43
25:0 5.45 1.52 1.99 0.17 0.25 1.57
26:0 9.30 2.60 3.88 0.33 1.01 6.45
27:0 2.72 0.76 1.85 0.16 0.12 0.75
28:0 4.45 1.25 4.65 0.39 0.31 1.96
29:0 0.03 0.20
Total 357.53 1180.73 15.67
0857R
30 08578
30 01030
30
40 50 60 70 80 90
40 50 60 'lO 80 90
40 50 60 'lO 80 90
Retention Time (min)
Fig. 16 TIC chromatograms of the fatty acid methyl-esters in Samples D857R, D857B and D 1030 obtained from the North Knoll of Iheya Ridge, Okinawa Trough.
42
1
100
100
100
wt.% D857R (Ambient sediment)
40.---�
• Me-branched
30 0 Monounsaturated
20 D Normal
10
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Chain length
wt.% 08578 (CaJyptogena colony)
40,---�
30 20 10
wt.%
• Me-branched
· · · · - ··· · · · - - - · · · · · ·- · · · · ·· · · -· · · [ill
Monounsaturated
0 Normal
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Chain length
01 030 (Calyptogena colony)
25 ---�
• Me-branched
20 [ill Monounsaturated
15 ·---·- --··---·· -- --- ·--- - · --- --- 0 Nonnaf 10
5
o ������������������+L������
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Chain length
Fig. 17 Fatty acid compositions of Samples D857B, D857R and Dl030.
43
Table� l·atty acto compt':-ottH.'Il 111 the :-.c..'dtnh.'tll sample on the top of the knoll, nonhern Kagoshtma Bay
Fatty acids 8:0
9:0 10:0
11:0 12:0
i13:0 ail3:0
13:0 14:0
il5:0 ai15:0 15:0 brl6:0 16:1�7 16:1�9 16:0 br17:0 isol7:0
ai17:0 17:0 18:2 18:1�9 18:1�11
18:0 br19:0 19:1 19:1 19:0 20:5 20:4 20:1 20:1 20:0 21:0 22:0 23:0 24:0 25:0 26:0 total
44
0345
0.11 0.07
0.21 0.12
0.27 0.16
0.14 0.09 1.39 0.82
0.48 0.28
0.19 0.11
0.46 0.27
11.37 6.73
3.90 2.31
5.34 3.16
4.81 2.84
1.93 1.14
43.07 25.49 12.04 7.13 25.84 15.30
1.29 0.76
1.16 0.69
0.79 0.47
2.38 1.41
4.14 2.45
11.61 6.87 11.77 6.96 7.95 4.71 0.59 0.35
0.54 0.32
0.41 0.25
1.10 0.65
1.65 0.98
3.20 1.90 1.71 1.01
0.53 032
1.05 0.62
0.43 0.26
0.70 0.41
0.16 0.09
0.68 0.40
0.02 0.01
0.09 0.05 168.96
20
0341
0345
30 40 50 60 70
Retention Time (min)
80 90
80 90
Fig. 18 TIC chromatograms of the fatty acid methyl-esters in Sample D341 and D345 of the Wakamiko Caldera.
100
100
wt.%
0345 Kagoshima Bay 90m depth
(Foot of
a Vestimentifersncluster)
40 �---�
•
Me-branched30 ···--·-··--·---·-··· - ····-·· · ··· ····---·-· ····-
It]
monounsaturated 20 -·-··-··-··-·--·· -··-···-- - ----··-··· . : - ···--·--·-··-··-·· -···-···--- --- - -
0
normal10
··--·-·--···---···-···-12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Chain length
Fig. 19 Fatty acid composition of Sample D345 from the Kagoshima Bay.
I :tl•k (• I ;til\ .ll.:td Ullllj)l''-lll\111, Ill iltl· 'L'dllllL'IIi ,,llllJ'k·, ,,, ilk
\I�OJlll CaldL'Ia. l;u-O�;l,:t\\,11.1 !\Jl'
01008 DIOII
)·all) and ... Jl}_:. � ', ,,�;;. \\l ',
10 () ()()I () 0.\
IJ·O () 02 () (\4
12:0 074 I 75
i 13:0 0.03 () '21 ou 0..10
ail3:0 (U14 0 28 0.05 0.13
13:0 0.05 0 .\() 0 09 0 20
isopn:no•dali-+:U UOI U U7
br 1-+:0 0.29 2.1X 0.67 1.5<)
1-U 0.11 O.R6 0.2() 0.62
1-l-:0 I. II 8.-+1 2.21 5.2-+
cyc150 0.09 0.65 0.50 !.1R
isoprcnoidall 5:0 () 1.1 0%
i 15:0 0 22 1.69 I 20
2.X-I-ail5:0 039 2.92 1 5-+ 3.66
15:1 () 07 0.56 0.03 0.07
15:0 0.62 4.67 1.04 2.47
16:? 0.14 1.02 0.18 0.42
isoprenoida116:0 0.05 0.35
16:1 0.04 0.28
brl6:0 0.17 1.29 0.58 1.38
16: 1�7 1.48 11.19 2.80 6.65
16: 1�9 0.19 1.45 0.57 1.34
16:0 2.62 19.75 9.17 21.76
br17:0 0.32 2.39 2.04 4.85
isoprenoida117:0 0.19 1.41
i17:0 0.06 0.49 0.38 0.89
ai17:0 0.22 1.70 0.69 l.o:\
17:1 0.15 1.16 0.49 1.16
17:0 0.35 2.66 0.85 2.02
18:3 0.04 0.31 0.18 0.43
18:2 0.10 0.74 0.15 0.35
18: 1f19 1.03 7.79 2.14 5.07
18: 1�11 0.35 2.64 1.90 4.50
18:0 1.74 13.16 3.55 8.42
br19:0 0.06 0.48 0.45 1.06
19:1 0.17 1.29 0.89 2.11
19:0 0.15 1.15 0.61 1.45
20:2 0.02 0.1�
20:1 0.02 0.16 1.15 2.73
20:0 0.16 1.17 1.00 2.37
21:0 0.05 0.34 0.51 1.20
22:0 0.11 O.ft\ 0.% 2.27
23:0 0.04 0.28 0.48 1.13
24:0 0.06 0.46 1.08 2.57
25:0 0.01 0.05 0.17 0.39
26:0 0.56 1.34
27:0 0.05 0.13
28:0 0.12 0.29
total 13.24 42.15
01008
01011
30 40 50 60 70
Retention Time (min)
80
90
90'
Fig. 20 TIC chromatograms of the fatty acid methyl-esters in Samples Dl008 and DlOll obtained from the Myojin Caldera, Izu-Ogasawara Arc.
100
100
wt.%
01008 Myojin Caldera
25�---�
20 15 10 5
•
Me-branched[ill
Monounsaturated0
normalo ��-P�������������-r--���--��
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Chain length
wt.% 01011 Myojin Caldera
25�---�
20 ·· ····· ··· ·· ·· ··· ··· ···· ······ · · · ····
15 10 5
II
Me-branchedtill
MonounsaturatedD
normalo ������-¥��������+--+�������
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Chain length
Fig. 21 Fatty acid compositions of Samples D 1008 and D 1011.
4-2. Characterization of the fatty acid compositions at the hydrothermal areas
62 kinds of fatty acids identified in the sediments sampled from around hydrothermal areas. Most of them are likely to originaly composed by bacterial metabolism. The fatty acids between C 12 and C 19 are one example (Lechevalier, 1977). The 16:0 fatty acids which ubiquitously exists in the most organisms, were predetermined in all of the samples ranging from 10.87 to 36.42% of the total acids. Other saturated straight-chain fatty acids found in both prokaryotes and eukaryotes were also significantly identified, although the odd
numbered fatty acids show relatively low content.
The significant amount of monounsaturated fatty acids in sediment samples suggests that prokaryotic organisms are predominant in the sediment samples (e.g. Parkes and Taylor, 1983; Perry eta/., 1979). In the three hydrothermal areas, the DESMOS Caldera of Manus Basin, the knoll at the east rim of the Wakamiko Caldera in Kagoshima Bay, and the Myojin Caldera of Izu-Ogasawara Arc, monounsaturated fatty acids were enriched, ranging from 21.52 to 48.35% of total fatty acids, whereas sediment samples from the Iheya Ridge show lower content of these fatty acids, ranging from 7. 51 to 28.67% of total fatty acids. In addition, the presence of unsaturated fatty acids between C 12 and C 19 are indicative of gram
negative bacteria (Lechevalier, 1977; Parkes and Taylor, 1983) and monounsaturated fatty acids of 16:1L\9 and 18:1L\9 are metabolized by microalgae (Findlay et al., 1986; Gillan and Hogg, 1984). Low contents ofPUFAs, ranging from 0.38 to 5.36% of the total acids, suggest that microeukaryotes dose not play an important role because the PUF As are a good proxy for microeukaryotes (Bobbie and White, 1980; Findlay et al., 1986; White, 1983). Taking into account such results by bacterial metabolism, deduced from the presence of unsaturated fatty acids and low content of PUF As, it is most likely that bacteria is the most predominant contributor of fatty acids in the sediment samples.
Relatively small amount of methyl-branched fatty acids ranging from 3.82 to 19.5% of total acids were detected in sediment samples. Sedeiment samples from the Iheya Ridge show lower contents of these acids (less than 1 0% ), although other samples show higher contents.
Significant amounts of these fatty acids are contained in anaerobic bacteria (Volkman et al.,
50
1980) and SRB (e.g. Taylor and Parkes, 1983 � 198 5), then the relative proportions of these fatty acids in the sediments reveal the contribution of anaerobic bacteria and SRB to sediments. Almost anaerobic bacteria are sorts of heterotrophs. Presence of these bacteria indicates alteration of organic matter by anaerobic metabolisms. Contents of methyl-branched fatty acids in this study are higher than that of the continental slope sediments (almost samples less than 10%) reported by Harvey (1994). Alteration of organic matters via anaerobic metabolisms must be an important process occurred at hydrothermal systems. On the other hand, higher contribution of anaerobic bacteria are reported from an eutrophic bay, the sediment containe much higher contents of methyl-branched fatty acids ( approx 3 0%;
Rajendran et al., 1992). It indicate that anaerobic metabolism is less important process than aerobic matabolissm around the hydrothermal areas. Four isoprenoidal fatty acids were detected in Sample D 1008, although the origin of them is unknown.
In this study, the low concentrations and/or absence of PUF As, such as linoleic acid
(18:3�9,12, 15),
and only small amount of the diunsaturated fatty acids are shown. These fatty acids are biomarkers for eukaryotic organisms. Around hydrothermal systeme large biomass of animals exist, although contribution of their biomarker are insignificant. The fatty acid profiles of this study areas are notably different with that of the reported results of other studies, which reported significant amount of PUF As in the sediments. Similar low PUF As profile patterns of fatty acids with this study are obsereved in sediments of the North Carolina continental slope (water depth 600�2000m; cf Harvey, 1994). The slope sediments are abundant in bacterial fatty acids. The less abundance of PUF As in the samples are concluded vigorous degradation by bacterial activity. Sample D1008 and D1011 were contained 18:3 acid, indicating contribution of diatom and/ or animals in the sediment of Myojin Caldera (Findlay and Dobbs, 1993). The remarkable amounts of 20:2�4 acids were recognized in Samples D916 and D921 indicate eukaryotes contribution in the sediment of DESMOS Caldera. In this case, tube-worms and other animals are the most possible source of the PUFAs. The presence of 20:4 and 20:5 in Sample D345 suggested the contribution of51
diatom (Perry et al., 1979) in the sediment of Kagoshima Bay. The water depth of sampling site of Sample D345 was within the euphotic zone, therefore, organic matters derived from photosynthetic planktons are expected to reach directly to the sediment surface, that is, large amount of unsaturated acids suggest relatively large input of organic matter from water column and sediment surface.
Characteristic compositions of the biomarker fatty acids are summarized in Table 7. The ratio between monounsaturated fatty acids and methyl-branched fatty acids interpreted to be a proxy suggesting which bacteria is predominant, that is, the ratio less than 1 indicate the predominance of anaerobic bacteria (Rajendran et al., 1992). The obsereved ratios in this study range from 0. 66 to 5. 21, and indicate obviously predominance of aerobic bacteria around hydrothermal systems except Sample D 1030 of Iheya Rdge. In addition, the sum of iso and anteiso form methyl-branched C 1s acids to normal C16 is likely indication for the proportions of the bacteria in the whole of sedimentary fatty acids (Mancuso et al., 1990;
Bobbie and White, 1980). The ratios obsereved in this study range from 0.03 to 0.53. The ratios of the sediments obtained from the Iheya Ridge, however, were relatively lower than that of other sediments, indicating lower contribuiton of bacterial fatty acids. The branched fatty acids are derived mainly anaerobic bactera, therefore, the ratios were lower than that of eutrophic bay sediment [(i15:0+ai15:0)/16:0 = 0.44� 1.13], in where anaerobic bacteria are co
dominant members (Rajendran eta!., 1992).
The concentrations of total fatty acids in Sample D916 and D921 of the DESMOS Caldera (131�184J.tg/g sediment) and Sample D345 of the Kagoshima Bay (169J.tg/g sediment) were at least two times higher than that of organic rich sediments from a continental slope in the region of the Cape Hatteras, U.S.A. (10� 70J.tg/g dry sediment; Harvey, 1994). In the slope region benthic biomass report about six times higher than at comparable slope areas in other region. The fatty acid concentration of the other sediments in this study ( 13.2 4�42.l5J.tg/g sediment) are comparable with the slope sediments. Therefore, fatty acid concentrations in the sediments of the hydrotharemal areas must be remarkably high, and the concentrations refrect the large biomass of chemosynthetic community. The sediment of the
52
hydrothermal areas in the Juan de Fuca Ridge shows much higher concentration of total fatty acids (24 7 �g/ g dry sediment� Hedrick eta!., 1992 ), related with large bacterial biomass of vent community. Sediments in submarine calderas are accumulated shorter period after caldera formations than usual marine environment. Hence, accumulated organic materials in the caldera floor are less than surroundings. Total fatty acid concentrations in sediment samples must be sufficiently higher than that of usual marine sediment.
The calculated biomass based on fatty acid concentrations in this study were widely distributed ranging from 29.2 to 405.8 X 10 8 cells/g (dry weight) sediment (Table 7). These values are 2� 3 order higher than that of an eutrophic bay sediments ranging from 0.1 to 1. 7 X 108 cells/g sediment (equivalent to 0.26�3.79�g fatty acid/g sediment� Rajendran etal., 1992).
The fatty acids in the eutrophic bay sediments are mainly bacterial origin. The magnitude of bacterial biomass of the hydrothermal areas are comparable with copious animal amount obsereved around hydrothermal vents, where animals appear 4 orders higher in amount than ambient seafloor. These results lead us the conclusion that the biomass of this study areas are much higher than that of the eutrophic bay sediments. Even for hydrothermal areas, contribution of terrigenous input would be a strong factor to control fatty acid composition of sediment. Fig. 22 shows fatty acid composition classified by configurations of alkyl chains, saturated, monounsaturated, methyl-branched and poly-unsaturated acids for all the samples of the hydrothermal areas. Sample D921 from the DESMOS Caldera and Samples D 1008 and D 1011 from the Myojin Caldera show similar pattern. For these sites, contribution of terrigenous material is considered as relatively low, because they are covered with only thin sediments. Samples D916 from the DESMOS Caldera and D345 from the northern Kagoshima Bay show similar pattern. The Kagoshima Bay is accumulated thick present deposits, although contribution of terrigenous material is significantly low. Both samples are recognized high concentration of fatty acids originated bacterial metabolisms because of high contents of monounsaturated fatty acids. On the other hand, Samples D857R, D857B and D 103 0 from Iheya Ridge showed enrichment in normal saturated fatty acids. The L/H ratios,
53
sum of short chain fatty acids (<C2o) to sum of long chain fatty acids (2::C2o), indicate the degree of contribution of terrigenous input (Fukushima and Ishiwatari, 1984 ). The ratios of D857R and D 1030 sediment were significantly low, indicating large contribution of terrigenous material. In fact, Okinawa Trough was covered with thick sediments (sedimentary rate were estimated as 1�2 mm/year; Tsugaru et al., 1991) provided from Asia continental shelf by turbidity currents. It is most likely that bacterial fatty acids in the sediments from Iheya Ridge are diluted by terrigenous material which is eventually derived by turbidity currents. Hydrothermal area of the Iheya Ridge is below euphotic zone, sufficient water depth prevents accumulation of organic material. At sampling site of Sample D345 in the Kagoshima Bay, where are covered mainly by volcanic ash and glass, sedimentation rate must be lower than that of the Okinawa Trough.
The 18: 1� 11 fatty acid, which is reported as a biomarker for Thiobacilli (Katayama
Fujikura eta!., 1982; Kerger eta!., 1986), is detected ranging from 0.92 to 9.6 6 of total fatty acids in this study. Thiobacilli, sulfur-oxidizing bacteria, is one of possible chemosynthetic bacteria found in the hydrothermal system (e.g. Durand eta!., 1993). Other fatty acid biomarker for chemosynthetic bacteria has not been reported, therefore estimetion of contribution of chemosynthetic bacteria to total fatty acids is difficult. Almost chemosynthetic bacteria is a sort of aerobic bacteria. Significant amount of monounsaturated acids in sediment samples of this study is most likely to reflect large production of chemosynthetic bacteria.
Vl Vl
Table 7 The relationship of the fatty acid compositions in the sediment samples obtained from the hydrothermal areas
Desmos Caldera Iheya Ridge Myojin Caldera Relative amount or ratio D916 D921 D857R D857B D1030 D1008
saturated(%) 35.49 51.65 77.65 66.78 78.92 53.29
monounsaturated(%) 43.84 34.10 13.60 28.67 7.51 26.94
branched(%) 16.83 13.25 7.28 3.82 11.38 17.07
PUFA (%) 5.36 4.42 1.44 0.73 0.38 1.23
br+odd( <C2o) (% )** 29.47 21.87 12.74 7.51 21.08 26.30
UH [2:( <C2o)/2:(�C2o)]* 3.12 3.74 2.46 7.62 1.71 16.01
(iso15:0+ai 15:0)/ 16:0** 0.53 0.21 0.04 0.03 0.17 0.23
monounsat./branched * * * 2.60 2.57 1.87 7.50 0.66 1.58
Total concentration(pg/g dry) 131.15 183.51 15.67 13.24
Biomass (lOS cells/g) 290.0 405.8 34.6 29.2
*an indication of the proportions of the autochthonous input (Fukushima and Ishiwatari) 1984).
**indices of the proportions of the bacteria (Bobbie and White, 1980; Mancuso et al ., 1990).
***an indication of the preference of aerobic to anaerobic bacteria (Rajendran et al., 1992).
DlOll 55.05 21.52 19.50 0.78 29.01 3.71 0.30 1.10 42.15 93.2
Kagoshima Bay D345
35.02 48.35 9.28 5.32 15.24 17.92 0.36 5.21 168.%
373.6
�
wt.%
80
60
---·-·· ···-···-··· -·······•·---- ---·-----·-···-··· · · ···- -
----DESMOS Caldera
1 I I I I I I I I I I
North knoll
Iheya Ridge : Myojin
: Caldera
I I I I I I I
1--· · · · · -·· · · ·- . ........... . . .. . . .. . . . I
I I
: Kagoshima :Bay
I I I I I I I
40---····-·� ... �---····· ··· ······ ..........
.
..
... .......... •···-···· ···-· ···· ··-· 1· · · - -·-·- - · - - - ··· -· .................
........ I• • • • • • · · • · •2oJI
0 ..
lli!ill 1 lliiiil il l
..................l l:m:l I I. I j!:!l!l J
bm... 'I
I I:;:;: ---··· ::::: ........... !' �HH --- --- - -· - nn� --- ...... :
.. ,.,.�...._ .... ...._ .. .. ,.,._,_ .... ..., , . "'"'"''- .... ,.,.- ro·
o·
•- ...-.-.--- ····- ..
0916 0921 0857R 08578 01030 01008 01011
Site
Fig. 22 Comparison of the fatty acid compositions by classification using alkyl chain types such as normal-saturated, monounsaturated, methyl-branched and PUFAs.
l!i!i!il ....
······--- -�
0345
D Saturated 0 Monounsaturated
• Me-branched
� Polyunsaturated
4-3. Distributions of sedimentary lipids in Sag ami Bay 4-3-1. Fatty acids
Concentration of total fatty acids in Sagami Bay of this study (0.06-0.371lg/g dry sediment) were 3-4 orders low relative to the sediments obtained the hydrothermal areas (13-169!lg/g dry sediment). The reported concentrations (0.7-7.8ng/g dry sediment from the southwestern Sagami Bay by Naganuma eta!., 1996) were less than the values of this study, although small higher concentration was reported (0.87!lg/g dry sediment from 1410m depth by Fukushima and Ishiwatari, 1984).
Compositions of fatty acids are shown in Table 8 and Fig. 23. The collected samples were divided into two types clearly based on compositions of the fatty acids. The Samples 2AC, 3AC and SAC represent relative low content of monounsaturated and branched fatty acids and the high content of saturated fatty acids listed in Table 9. As clear in this table, two grpoups show distinct L/H ratios. The lower L/H ratios ( <3) are considered to relate with higher contribution of terrigenous material (Fukushima and Ishiwatari, 1984). These results indicate relatively lower contribution of bacteria and higher contribution of terrigenous organic matter at these three samples. Sample SAC also can be distinguished from Samples 2AC and 3AC, by relatively higher content of monounsaturated fatty acids. At only sample SAC, the ratio of monounsaturated to methyl-branched fatty acids was lower than 1, indicating a preference for anaerobes to aerobes (Rajendran eta/., 1994). Samples lAC, 6AC, 7AC and 8AC are characterized by relative low content of long chain fatty acids and saturated fatty acids.
4-3-2. Hydrocarbons
Normal alkanes were identified ranging from C 16 to C34 by GC/MS. Their concentrations ranged from 7.9ng/g dry sediment of Sample 6AC to 24ng/g of Sample 7AC (Table 10 and Fig.
24). Samples 2AC and 7 AC are enriched in n-alkane. The values of CPI range from 1.14 of Sample lAC to 2.68 of Sample 3AC. Samples 3AC and SAC are located off Sakawa River and the CPI values are larger than 2, therefore, these sediments can be divided from the other
57
sediment samples.
4-3-3. Fatty alcohols, phytol and cholesterol
Concentrations of saturated normal alcohols were determined ranging from 6ng/g dry sediment of lAC to 64ng/g of2AC in Table 11 and Fig. 25. Even carbon number preferences in distributions of individual fatty alcohols was observed. In Table 11, the cholesterol, only cholest-5-en-313-ol, was identified from all the sediment samples, and the phytol was also detected from the six sediments except SAC (under identification limit). Cholesterols are useful biomarker in the sediments ( cf. Volkman, 1986). Presence of cholest-5-en-313-ol reflects activity of zooplankton grazing (Prahl et al., 1984: Harvey et al., 1987). This cholesterol was most abundant in Sample 6AC. Samples 2AC, 3AC and 8AC, located near the coastal line, were also abundant in this cholesterol.
The long chain fatty alcohols (2:C2o) were also most abundant in the sediments of 2AC and 3 AC, which located close to coastal line. Generally the short chain fatty alcohols ( <C 20) are derived from microbes and algae and the long chains are derived from higher plants (e.g.
Robinson et al., 1984). Fig. 26 shows the concentrations of higher plants origin fatty acids and alcohols. Sample 7 AC locates far from the coastal line, however, the concentration of terrigenous organic matter at this site is relatively high. In sediment sample 8AC the concentration of those organic compounds is the lowest among all the sediment samples, whereas, the phytol concentration is the highest.
Table 8 Fatty acid compositions in the sediment samples obtained from the Sagami Bay (ng/g dry sediment).
Fatty acids lAC 2AC 3AC SAC 6AC 7AC 8AC
9:0 0.12 0.08 0.17 0.05
10:0 0.28 0.01 0.03 0.12 0.20 0.24 0.44
11:0 0.12 0.04 0.24 0.43 0.24
12:0 0.73 0.17 0.38 0.89 1.% 4.34 0.76
i13:0 0.43 0.04 0.07 0.10 0.37 0.30 0.17
ai13:0 0.36 0.04 0.05 0.11 0.39 0.41 0.13
13:0 0.21 0.05 0.02 0.16 0.39 0.19 0.21
br14:0 0.69 0.28 0.43 0.63 2.17 2.66 0.41
14:0 3.68 1.51 2.77 4.47 9.82 12.21 3.43
i 15:0 1.68 0.53 0.67 1.45 3.42 3.23 1.16
ai 15:0 4.41 1.31 1.03 2.36 7.02 7.58 2.43
15:0 1.32 0.82 1.12 2.12 4.27 4.75 1.24
br16:0 0.83 1.84 1.76 2.41 1.82 0.62
16:1�7 9.49 5.30 3.13 1.06 16.92 20.01 6.07
16:1�9 2.34 1.15 0.72 1.90 4.37 4.18 1.31
16:0 28.41 88.26 69.45 42.88 62.21 78.24 19.85
br17:0 3.47 1.73 1.13 0.67 3.89 6.35 1.18
i 17:0 0.79 0.83 1.46 0.54 1.18 3.14 0.65
ai 17:0 1.79 1.59 1.46 0.64 1.27 7.39 0.69
17:1 1.75 0.76 2.82 6.82 0.59
17:0 2.15 4.90 3.43 3.18 4.20 10.38 1.16
18:2 1.09 0.89 1.95 0.62 2.43 15.82 1.21
18:1L\9 7.93 5.19 3.52 1.42 9.50 23.80 5.59
18: 1L\11 7.34 4.31 1.73 1.02 6.81 14.16 3.69
18:0 8.55 24.99 20.68 9.19 11.13 21.19 5.10
19:0 1.39 5.83 3.28 4.94 7.55 11.47 0.63
20polyen 7.71 11.51
20:1 12.74
20:0 2.22 9.21 8.88 2.73 3.93 10.73 1.65
21:0 1.80 7.44 7.25 2.08 3.17 7.78 0.37
br22:0 2.56 9.52 5.12 1.87 6.71 6.89 0.66
22:0 3.99 24.98 18.79 4.82 7.31 14.48 0.96
23:0 2.54 8.48 8.96 1.09 6.09 14.48 0.55
24:0 9.11 34.09 22.12 9.65 8.70 10.51 0.93
25:0 2.30 5.02 6.39 1.27 1.88 17.97
26:0 4.46 11.71 13.62 3.66 3.59 4.22
Others 1.99 7.26 0.83 0.50 1.20 1.57 2.19
Total(<20) 91.24 152.30 128.09 80.50 167.03 285.52 59.02
Total(�O) 28.98 110.45 91.13 27.17 41.37 87.04 5.13
Total 122.21 270.00 220.04 108.16 209.59 374.14 66.34
wt.0/o
30
Site1 20
10
30
Site2 20
10
30
sne3 20
10
Snes 20
10
30
S�e6 20
10
S�e7 20
so
srrea 20
10
Chain length
9 1 0 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
9 10 11 12 13 14 915
I() � ...
.0
16 17 18 19 20 21 922 23 24 25 26
� .0
Chain length
Fig. 23 Fatty acid compositions of the Sagami Bay sediments. Open columns;
saturated, hatched columns; monounsaturated, filled columns; methyl
branched fatty acids.
60
·Table 9 The relationship of the fatty acid compositions in the sediment samples of the Sagami Bay
Relative amount or ratio lAC 2AC 3AC SAC 6AC 7AC 8AC
saturated(%) 59.96 84.24 85.11 86.24 65.23 59.81 56.67
monounsaturated(%) 23.60 6.18 4.14 4.99 19.29 18.43 25.99
branched(%) 11.82 3.03 3.66 6.02 10.56 8.79 11.21
PUFA(%) 0.89 0.33 4.39 0.57 1.16 7.30 1.83
br+odd(% )** 17.51 7.61 7.29 15.66 19.88 17.93 17.42
UH [L( <Czo)IL(�Czo)]* 3.15 1.38 1.41 2.96 4.04 3.28 11.51
0\ (iso15:0+ai 15:0)/15:0** 4.59 2.25 1.52 1.80 2.45 2.28 2.89
-(iso15:0+ai15:0)/16:0** 0.21 0.02 0.02 0.09 0.17 0.14 0.18
monounsat./branched * * * 2.00 2.04 1.13 0.83 1.83 2.10 2.32
18: 1�11118: 1�9*** 0.93 0.83 0.49 0.72 0.72 0.59 0.66
*an indication of the proportions of the autochthonous input (Fukushima and Ishiwatari, 1984).
**indices of the proportions of the bacteria (Bobbie and White, 1980; Mancuso et al ., 1990).
***indices of the preference of aerobic to anaerobic bacteria (Bobbie and White, 1980; Rajendran et al., 1992).
Table I 0 :\lkanL' (IJlllpo:-;Jtlons 111 the sediment samples obtained from the Sat!-allli 13ay (ng/g dl)' sediment).
Carbon number 1A 2AC 3AC SAC 6AC 7AC 8AC
16 0.245 0.361 0.264 0.265 0.552 0.512
17 0.354 1.421 1.393 0.769 0.374 1.524 1.015 18 0.266 1.884 1.775 1.057 0.357 1.359 0.547 19 0.606 2.651 2.628 1.125 0.964 2.735 0.964
20 0.365 2.371 0.642 2.578
21 0.204 0.978 0.826 0.614 0.494 1.352 0.465 22 0.299 1.069 0.860 0.651 0.996 1.573 0.065 23
24 0.658 0.674 0.057 0.418 0.812 0.894
25 0.399 1.486 0.159 0.753 0.573 1.137 0.755 26 0.356 1.088 0.091 0.076 0.403 1.034 0.518 27 0.830 1.139 0.285 0.349 1.011 1.340 1.145 28 0.637 1.361 0.169 0.715 0.413 0.938 0.624 29 0.714 1.693 0.5% 1.039 0.606 1.892 1.310 30 0.566 0.885 0.132 0.355 0.188 0.625 0.381 31 0.673 1.245 0.515 0.705 0.327 1.596 1.169 32 0.624 0.628 0.587 0.460 0.305 0.903 0.741 33 0.275 1.338 1.229 0.287 0.274 1.899 0.911 Total 8.072 22.272 11.569 9.637 7.927 23.848 12.017 CPI* 1.14 1.37 2.68 1.48 1.70 1.92 2.00
*Carbon preference index as simple ratio of (C27+C29+C31 +C33)/(C26+C28+C30+C32)
ng/g dry sediment
1 Slte1 0.5
3 ---
---Site2 1
3 --- ---- - --- ------ ----- ----- - - -- - - ---- -- -
----2
Site3 1
1.5 ---1
SiteS 0.5
Slte6
3 --------------
---Slte7 2 1
Slte8
18 17 18 18 20 21 22 23 24 25 28 27 28 29 30 31 32 33
Chain Length
Fig. 24 n-Alkane compositions of the Sagami Bay sediments.
63
T:thk II I he Cl'llccntt;ltll.'th �_,j tndt\ tdll.li n-.lk�_)h,,]-,_ ph� tnl and st�rol p1c�cnt 111 the sediment ·amplcs obt<11n�d frnm the Sat!�lllll B�1� (11):!. t! dr� sediment).
Carbon number lAC 2A( 3AC 5AC 6A 7AC 8AC
12 0.227 0 . .347 0.-W{) 0.608 0.292 0.870 0.510 13 0.262 0.772 0.675 0 . .5-+7 0.327 0.598 14 0.310 2.378 1.946 1.665 0.925 2.797 1.187
15 2.808 0.726 0.598 1.657 0.641
16 0.657 1.514 4.010 1.447 0.794 3.543 1.365
17 0.492 0.300 0.366
18 0.369 1.550 1.4� 1.314 0.981 2.375 1.021
19 0.281 1.550 1.667
20 0.791 3.433
21 0.283 2.648 0.170 0.873 1.641 0.990
22 1.144 30.099 34.566 15.766 6.825 7.180 4.605
23 0.592 1.862 0.362 0.262 0.599 0.716
24 0.743 4.733 1.100 1.465 1.231 1.755
25 0.917 0.116 0.399 0.451
26 3.060 0.923 1.173 0.717 1.211
27 0.155 0.365 0.446
28 0.671 10.259 5.074 2.861 1.556 4.857 1.983
29 0.595 0.102 0.507
30 2.707 1.786 1.396
Total(<20) 2.107 10.920 10.142 6.799 4.218 11.243 5.691
Total(;?:20)* 3.259 23.480 11.201 9.710 4.103 10.804 8.949 Total* 5.366 34.400 21.343 16.509 8.321 22.047 14.639
Phytol 0.446 3.991 2.752 1.068 1.036 5.514
Charest- 0.612 3.008 2.849 1.003 11.582 2.630 2.773 Sen-38-ol
*The concentration of C22 alcohol excluded from total contamination because of laboratory contamination.
n9"g dry sediment
Site1
Site2
Site3
SiteS
Site6
Srte7
Site a 0.75
0.5 0.25 0 12.5 10 7.5
5 · - - - - - -- - - ·
2.5
o ������L-���-.�������������
6 ---5 ·
-4 ---3 2
1
o����--�L-��
3 ------ - ---
--2
---0
���������.-��L,����������---2 ---1.5 ---- - -- --------------------------------
---0.5
0 ..._.,...,._ ... __..L
6 ---4
--- o������---6
5 ---4
---3 ---2
Fig. 25 n-Alkanol compositions of the Sagami Bay sediments.
65
nglg dry sediment
150�---100
50
0
1 2 3 5
Site