19. TETRAPYRROLE PIGMENTS IN DSDP LEG 38 SEDIMENTS

Transcription

1 19. TETRAPYRROLE PGMENTS N DSDP LEG 38 SEDMENTS Earl W. Baker, Susan E. Palmer, and Katherine L. Parrish, Department of Chemistry, Northeast Louisiana University, Monroe, Louisiana NTRODUCTON Thirty-four ores from eight sites drilled in the Norwegian-Greenland Sea were examined for tetrapyrrole pigment ontent. (See Table 1 for sample desription.) The major thrust of this investigation was to disover the distribution of tetrapyrrole pigments with respet to geologi age and depth of burial. The bulk of the onlusions drawn here is based on the UV-visible absorption data obtained from the ore extrats. SAMPLES AND PROCEDURES All ores were stored frozen until the time of analysis. Where sample size permitted, 100 g (wet weight) were used for eah analysis. Sine only small ore wedges were provided from Sites 341 and 344, 50 g (wet weight) of sample were examined. The proedures followed for the extration and isolation of tetrapyrrole pigments from these ores have been desribed in previous nitial Reports (Baker and Smith, 1973; Smith and Baker, 1974; Baker and Smith, 1975a). An experimental flow sheet is presented in Figure 1. A Bekman ACTA CU ultraviolet-visible sanning spetrophotometer was used to obtain absorption spetra. Mass-spetral data were obtained using a DuPont BR mass spetrometer equipped with a solid sample probe inlet system and digital mass marker. The pigment sample was applied to the rounded end of a 2 X 15 mm sealed-glass apillary tube inserted into the probe rounded end out. This method of sample introdution brings the sample loser to the eletron beam, and a larger portion of nonvolatile tetrapyrrole is arried into the ion beam as ompared to the onventional method. RESULTS AND DSCUSSON UV-visible absorption spetral data are presented in Table 1. Of the 34 ores examined, 14 ontained a nondetetable level of pigment. These nonprodutive ore samples ranged from to Eoene in age. n general, pigments were more abundant in the Mioene to Eoene sediments than in sediments (Table 1). Site 338 Cores 11 and 17 from Site 338 ontained pigments with hlorin-type spetra. n addition, another pigment fration having the UV-visible spetrum shown in Figure 2 was isolated. A fration of this pigment from Core 17, eluted with THF from Grade Alumina, had a mass spetrum bearing some resemblane to those of hlorins reported by Baker (1970) and Baker and Smith (1973, 1975a). At this time, we will only report the m/e values, as a struture has yet to be assigned (see "hlorin," Table 2). Site 341 Small amounts of pigment having a hlorin-like visible spetrum were found in the upper 15 to 30 meters of sediment (Cores 2 and 4, respetively), with inreasing amounts at 64 to 67 meters (Cores 6 and 8, respetively). A marked derease in hlorin was noted at 70 meters (Core 10). was present in these sediments (Core 4 at 35 m). ( was again observed in Core 344-5, -, at about 30 m depth.) The ombination of free-base hlorin and vanadyl porphyrin is unusual and unexpeted. Only one ourrene of vanadyl porphyrin in DSDP sediments has been reported previously (Baker, 1971). t is generally believed that vanadyl porphyrins are thermodynamially more stable and therefore that they represent a later stage in diagensis of the hlorophyll moleule than freebase hlorins. Probably these deposits, olleted from the Lofoten Basin, were derived from a mixture of very old and very young sediments. A typial UV-visible spetrum was obtained for the vanadyl porphyrin in Core (Figure 3); in addition, there was a small peak at 590 nm; this may be due to small amounts of rhodo-type porphyrins (Baker, 1971). Only a trunated series, with the largest m/e peak at 541, was obtained mass spetrometrially (Table 2). A omplete series would be: 583, 569, 555, 541, 527, 513, and 499, eah 14 m/e units apart (Baker, 1971). The m/e peak appearing at 577 does not fit the normal expeted series, however, it is indiative of the rhodo series: n (Baker et al., 1967). Mioene sediments (384 to 451 m) olleted at Site 341 ontained pigments with hlorin-type spetra, nikel porphyrin helates, and pigments having spetra similar to pigments from Site 338 ("hlorin "). Freebase porphyrin was also indiated by UV-visible spetra. Free-base porphyrin (DPEP) has only been noted at 2 sites (Baker and Smith, 1975a) out of more than 40 DSDP sites examined. These ore samples (Cores , 30, 32, 34) were ombined in order to have workable amounts of pigments (Table 1). The nikel porphyrin fration isolated from Alumina Grade with 1% 1,2 dihloroethane in benzene displayed a 1:1 a\ß ratio (Figure 4). Suh a ratio is markedly different than the usual 3:1 ratio. Although mass spetral analyses were attempted on this fration, no interpretable spetra were obtained. 785

2 E. W. BAKER, S. E. PALMER, K. L. PARRSH TABLE 1 Tetrapyrrole Pigments in Core Samples From Leg 38 Setion Geologi Age Depth of Burial a Organi Carbon a (% by wt) ndividual Pigment Yield b (µg/g) UV-Visible Absorption Spetra (nm) Pigment Type (T) (T) (B) (B) (T) (B) d d d d (B) 343-l-2(B) (T) (T) (B) (T) (T) (B) (B) (T) or Eoene M. or L. Eoene E. Mioene (Mixed) (Mixed) or or or or E. Mioene E. E. Eoene E. Eoene - Mioene or E. L. Eoene (?) Eoene d ( () 395 () (405) (550) (530) (550) () () () () " " " " " " " " " " Nikel porphyrin " " Nikel porphyrin " " and free-base porphyrin " " Nikel porphyrin Nikel porphyrin a Data obtained from Leg 38 summary. "Pigment yield alulated by using the following molar extintion oeffiients: 550 nm; vanadyl porphyrin = at 570 nm. Not alulated. pheophytin "a" = at nm; nikel porphyrin = at d , -30, -32, and -34 ombined. Site 342 -type spetra were obtained for Core 6 (early Mioene) as well as pigments with, 584,, nm spetra. This is not an unommon ourrene, sine hlorins were found in to late Eoene sediments olleted during earlier legs (Baker and Smith, 1975b). The amount of hlorin found in (B) (0.034 µg/g) is similar to the amount of hlorin (0.024 to 0.09 µg/g) reported for Mioene 786

3 TETRAPYRROLE PGMENTS Sediment ores frozen at -20 C Ball mill extration with aetone: methanol, 9:1 U.V.-visible spetra of total extrats Sephadex LH20 hromatography with THF as solvent s i Diazomethane - Esterifiation U.V.-visible Porphyrins & metalloporphyrins Sugar hromatography with ylohexane, benzene, ethyl ether U.V.-visible of sugar frations Alumina grad hromatography 1,2 Dihloroethane 50* 1,2 Dihloroethane in benzene in benzene Nikel Porphyrins MSA demetallation U.V.-visible neutralization- Vanadyl Porphyrins -»-Mass Spetrometry-*- Figure 1. Experimental flow sheet. f Free base porphyrins and hlorins depth. The absene of vanadyl porphyrin in Core may reflet a differene in geologial setting: Site 346 was on the east slope of Jan Mayen Ridge, whereas Sites 341 and 344 were in the Lofoten Basin. Core 15 (at 130 m) ontained relatively large amounts of nikel porphyrin (0.036 µg/g). The nikel helate was onverted to the free base by treatment with MSA at 100 C for 1 hour, and the free-base porphyrin with the following UV-visible spetrum was obtained after neutralization with sodium arbonate and extration with ethyl ether: 395, 495, 520, 563, 618 nm. Based on the nature of this absorption spetrum and mass spetral data (Table 2), this pigment was interpreted to be a mixture of DPEP and etioporphyrin (Baker, 1969). The mass spetrum displays these two series: etio = w and DPEP = n (Baker, 1969), both series inorporating the natural abundane of Ni 58 (67.8%) and Ni 60 (26.2%). Thus, the m/e peaks appear in groups of three, for example, m/e 532, 534, 536. A preise interpretation of the mass spetrum would require lower bakground than was ahieved with the small amount of sample available for this study. We estimate the DPEP: etio ratio to be 2:1 based on relative mass spetral peak intensities and the free-base absorption spetrum. 350 WAVELENGTH (nanometers) Figure 2. UV-visible spetrum of "hlorin " from samples from Leg 31 sediments (Baker and Smith, 1975a). Site 346 Small amounts of hlorin were found at 30 and 87 meters (Cores 4 and 10, respetively). Core 4 was examined to a greater extent for omparison with Cores and 344-5, also from approximately 30 meters SUMMARY Tetraypyrrole pigments were found in sediments ranging from to Eoene in age. Although hlorins were abundant in Mioene sediments, their presene was generally harateristi of younger () sediments. No mass spetral analyses were made on hlorins isolated during this study. Nikel porphyrins were found in the older (-Eoene) sediments olleted during Leg 38. The distribution of these pigments is not unlike those reported in previous DSDP studies (Smith and Baker, 1974; Baker and Smith, 1975a, b). Nikel DPEP and nikel etioporphyrin were present in at least one Eoene sediment (Core ). We annot make any statements onerning the nature of the other nikel helates; higher onentrations would be needed in order to study their strutures in greater detail. n two samples vanadyl porphyrins and hlorins were found together. n Core 341-4, they were present in approximately qual onentrations, while in Core the hlorins were one-third as abundant as the vanadyl porphyrin. Previously, vanadyl porphyrins were noted in Tertiary sediments (Baker, 1971); we suggest that the ombination of hlorins and vanadyl porphyrins found here is not a normal distribution and may be due to mixing of older with younger sediments. The presene of free-base porphyrins was indiated (by UV-visible spetra) in middle Mioene sediments of Site 341. Their ourrene was oupled with hlorin (Core ), nikel porphyrin and "hlorin " (Cores , 30, 32, and 34). The ourrene of freebase porphyrin was noted earlier by Baker and Smith (1975a) in two -Mioene sites. No judgment an be made onerning this rather odd mixture of tetrapyrrole pigments present in these middle Mioene sediments without a more omplete study. " 787

4 E. W. BAKER, S. E. PALMER, K. L. PARRSH Core a TABLE 2 Mass Spetra of Leg 38 Tetrapyrrole Pigments Mass Spetrum (m/e) Peak intensities (normalized to 100 for the largest m/e peak) Pigment Type " " Nikel porphyrin 350 WAVELENGTH (nanometers Figure 3. UV-visible spetrum of nikel porphyrin from ore 341 (28-32). WAVELENGTH (nanometers)," present in three or and five Mioene-Eoene sediments, has not been reported in earlier DSDP sediments. ACKNOWLEDGMENTS This researh was supported by the Oeanography Setion of the National Siene Foundation, Grants GA-43359X and DES A01. REFERENCES Baker, E.W., Porphyrins. n Eglington, G. and Murphy, M.T.J. (Ed.s), Organi geohemistry: New York (Spinger-Verlag), p. 479., Tetrapyrrole pigments. n Bader, R.G., Gerard, R.D., et al., nitial Reports of the Deep Sea Drilling Projet, Volume 4: Washington (U.S. Government Printing Offie), p Figure 4. UV-visible spetrum of vanadyl porphyrin isolated from ore , Porphyrins in deep oean soures. Petroporphyrins from Challenger Knoll oil bearing ores: Chem. Geol., v. 7, p. 45. Baker, E.W. and Smith, G.D., Chlorophyll derivatives in sediments, Site 147. n Heezen, B.C., MaGregor,., et al., nitial Reports of the Deep Sea Drilling Projet, Volume 20: Washington (U.S. Government Printing Offie), p. 943., 1975a. Chlorophyll derivatives in DSDP Leg 31 Sediments. n ngle, J.C., Karig, D.E., et al., nitial Reports of the Deep Sea Drilling Projet, Volume 31: Washington (U.S. Government Printing Offie), p b. Chlorophyll derivatives in DSDP Leg 14, 20, 26, 27, and 29 Sediments. n ngle, J.C., Karig, D.E., et al., nitial Reports of the Deep Sea Drilling Projet, 788

5 TETRAPYRROLE PGMENTS Volume 31: Washington (U.S. Government Printing Of- Smith, G.D. and Baker, E.W., Chlorophyll derivatives fie), p in DSDP Leg 22 sediments. n von der Borh, C.C., Baker, E.W., Yen, T.F., Dikie, J.P., Rhodes, R.E., and Slater, J.G., et al., nitial Reports of the Deep Sea Drill- Clark, L.F., Mass spetrometry of Porphyrins : ing Projet, Volume 22: Washington (U.S. Government Charaterization of petroporphyrins: J. Am. Chem. So, Printing Offie), p v. 89, p