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| Dr. John Delano | Dr. Sherwood Chang | Dr. Carleton Moore | Dr. Michael Gaffey | Dr. John Bradley | Dr. David Ward | Dr. Jim Napolitano | Dr. John Jones | Dr. Graham Ryder | Dr. Leslie Orgel | Dr. Paul Butler | Dr. Lynn Margulis | Dr. Jim Kasting | Dr. Deane Peterson | Dr. George Flynn | Dr. Wayne Roberge | Dr. J. W. Schopf | Dr. William Irvine | Dr. David Koerner | Dr. Alan W. Schwartz | Dr. Laura Landweber | Dr. Everett K. Gibson | Dr. Martin A. A. Schoonen | Dr. Alan Boss | Dr. Paul Butler | Dr. Niles Lehman | Dr. Eric Herbst | Dr. Chris Chyba |
We hope that these interviews and lectures will provide useful supplementary material for courses and discussions on the origins of life as well resources for those who are not near to a site where they can hear about the latest developments in this field of research. If you have questions or comments on the interviews or lectures contact me at the email address below.
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| Janet Siefert, Ph.D. | Phone:713-348-3891 | Rice University | FAX: 713-348-5476 | Dept. of Statistics MS 138 | URL: www.stat.rice.edu/~mathbio/siefert.html | P.O. Box 1892 | Houston, Texas 77251-1892 |
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COSPAR F3.5 - Planetary Protection Panel #1 Meeting report
The F3.5 meeting on Planetary Protection (PP), also sponsorized by the Planetary Protection Panel (PPP), was held on the morning of July 18, and collected a good attendance (average number of participants about 30). Ten presentations of the eleven previously planned were given and were focused on three major topics : planetary protection policy, and Europa and Mars exploration. Mars and Europa are presently the main solar system targets for exobiological exploration and experimentation. The search for life and for organic compounds related to life, as well as missions designed to bring back samples to Earth (from Mars, particularly) have increased greatly the importance of sound planetary protection activities.
In the first presentations dedicated to planetary protection policy aspects, three main points were discussed. The first was the need for the COSPAR international planetary protection policy, the consolidation and promulgation of which was defined as the main task of the new COSPAR Planetary Protection Panel (PPP), which depends on the expertise of Commissions B and F, and is intended to involve the participation of representatives of all spacefaring nations, and liaison with other scientific bodies. In the past, COSPAR planetary protection resolutions have been issued and updated without the provision of a consolidated document. The goal is now to write and submit to COSPAR, for the next Scientific Assembly in 2002, a complete and updated policy. This will enable all concerned space agencies to have clear access to the approved COSPAR planetary protection guidelines. The second point dealt with ethical problems concerning other celestial bodies, with the prospect of exploration by uncontrolled entities which may involve in-situ activities (tourism, mineral extraction, etc.) without taking into account planetary environmental preservation. It was advocated that the overall COSPAR policy framework for space environments not be limited to the prevention of biological contamination. The third point concerned the ethical considerations linked to eventual discovery of an extraterrestrial form of life on another body, or in returned samples. The focus was on the discovery of microbial, unintelligent life, and was analyzed in parallel with the guidelines concerning to the discovery of eventual extraterrestrial intelligence through radioastronomy antennas (SETI). Compared to SETI activities, which would necessarily involve the immense distances and delays of interstellar space, the discovery of life in returned samples added immediate planetary protection constraints and considerations. The management and development of appropriate requirements and guidelines for the discovery of living entities in this solar system is an important and timely activity.
The second topic addressed concerned the exploration of Jupiter's moon, from the planetary protection point of view. The need for specific COSPAR policy guidelines is now evident, given the likely discovery of a huge, ice-covered water ocean by the ongoing Gallileo mission-giving this moon a high exobiological interest. A first work has been performed by the Space Studies Board (SSB) of the US National Research Council, which, in a report released in June 2000, addressed the probability of Europa biocontamination by terrestrial microorganisms. Also, in 1998, the SSB addressed the potential biohazard linked to sample return. At first approach, an Europa planetary protection policy should be very similar to the previous guidelines for Mars, but will include the possibility of global contamination in a full Europan ocean. Additional precautions, over those for Mars, will be required for all future Europan exploration missions.
The last topic of the meeting dealt with Mars exploration. Mars today is the main target for exobiological exploration and experimentation and a number of missions are ongoing (Mars Global Surveyor), in integration phase (Mars Express and Mars 2001 Orbiter) and planned, including orbiters, landers and sample return systems. After a discussion about the risk of Earth contamination by martian meteorites, the ESA Mars Express planetary protection implementation was presented. This mission is planned for a launch in 2003 and includes a Category III orbiter and a Category IVa+ lander, named Beagle 2, that is designed to conduct in-situ indirect exobiological experimentation (a search for organic compounds related to life) requiring a high level of organic contamination cleanliness. The Mars Express presentation was followed by the presentation of the specifications written for the Mars Sample Return (MSR) mission, presented by JPL for the NASA components, and by CNES for the French vehicles. The basis of these requirements was the present MSR mission scenario, which is planned to be updated at the end of 2000. The CNES presentations included also some sample quarantine aspects, and a description of the French availability to participate in such a program phase. The quarantine topic did not go into details of biohazard testing and life detection protocols, as was previously done at the 1998 scientific assembly. The last scheduled presentation by NASA on a Mars sample curation facility was unfortunately cancelled.
The session ended in the evening with the PPP (Planetary Protection Panel) business meeting. The schedule for the COSPAR 2002 PPP was discussed and approved by all present. The WSC session will be organized jointly with IAF, IISL and the IAA. A one day session is proposed, including four major topics : PP linked to Solar system exploration, PP linked to Earth protection, PP concerns in human exploration and activities on other bodies, and lastly PP policy, ethical and legal issues and public communication.
Andr Debus
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COSPAR F3.4-2 / B0.8
Extra-terrestrial organic chemistry: From the Interstellar Medium to the Origins of Life
Part II : Complex organic chemistry in the environment of planets and satellites
F3.4.2 meeting on extra-terrestrial organic chemistry in the environment of planets and satellites was held on July 20. This COSPAR event was also sponsored by Centre National d'Etudes Spatiales (CNES), European Space Agency (ESA), International Society for the Study of the Origin of Life (ISSOL) and University of Paris 12 - Val de Marne. It was organized by F. Raulin and K. Kobayashi. The aim of this event was to cover and review the many new data which have been recently obtained and to give new insights on those which are expected in a near future in our knowledge of the complex organic chemistry occurring in the several planets and satellites of the Solar system, outside the Earth, and their implication for exobiology and life in the universe.
This meeting was very well attended (with an average number of participants around 60). 19 papers were presented, including 9 solicited, 4 oral contributed and 6 poster (for which a short oral summary was presented). The event was composed of two main parts. The first one was mainly devoted to the inner planets and Europa, and the search for signature of life or organics in those environments. The second part was related to the case of the outer solar system.
A. Brack (France) started the morning session with a general presentation on planetary liquid water and its essential role in the origins of Life, together with CHONS organic matter. He emphasized the unique properties of this universal solvent, its occurrence on the early Earth, but also its likely presence on Mars, at least in the past, and on Europa, where organic chemistry could also be present and life could have thus emerged too
T. Saito (Japan) then described the importance of fluorescence microscopy for searching for traces of life in extraterrestrial samples, in particular for identifying micro-organisms in Martian soil samples. He also described the characteristics and performances of a space instrument prototype, already available.
P. Rannou (France), presented the concept of a new simulation chamber which is under development for exobiological studies of Mars environment. This low pressure, low temperature chamber will be first oriented to study the past evolution of Martian regolith, in particular the behavior of hydrogen peroxide, from exobiological, chemical and mineralogical points of view.
C. Rodier (France), described the development of techniques of chemical derivatization for analyzing refractory organics by GC and GC-MS in extraterrestrial environments. Such techniques should be ready soon for in situ analysis of Mars soil.
R. Navarro-Gonzalez (Mexico) presented the results of a new experimental study simulating the potential organic syntheses on early Mars by volcanic lightning. Many products could have been formed through this process, including hydrocarbons and HCN.
Similar and complementary results have been obtained in a wide range of laboratory experiments simulating the evolution of planetary atmospheres under high energy particles or photon bombardment, as reviewed by K. Kobayashi (Japan). The results suggest that N-containing organics, such as amino-acids precursors, are formed chiefly with high energy particles, but not with UV photons.
Atmospheric nitrogen fixation is a key step in the chemical evolution of planetary environments. D. Nna Mvondo (Mexico & France) presented preliminary results of a general study on this topic, carried out through simulation experiments. It was shown the importance of the formation of NO and NO2 in a CO2-N2 rich atmosphere by lightning discharges.
V.A. Basiuk (Mexico) has study the formation of peptides from amino acids and a variety of oxides. His results shows that abiotic peptides formation can occur in a large variety of planetary environments, under mild temperature conditions, given the presence of amino acids and alumina containing minerals. Delivery from space may have been an important source of amino acids on the primitive Earth, and may still be a source on many planets of the solar system today. V.A. Basiuk has also study the survivability of those molecules during the atmospheric entry, by experimentally studying their behavior to pyrolysis. The results suggest that a noticeable fraction of these compounds may, indeed, survive.
Many of these organics, in particular N-organics are present in interstellar grains, where they are formed by ion irradiation of ices. G. Strazulla (Italy) gave a review on the production of organics by ion irradiation of ices and emphasized the importance of CN-bearing species.
The afternoon session was devoted to the outer solar system. First J.-C. Guillemin (France) reviewed the many results which have been obtained in the laboratory on the photochemical production of a variety of organics from irradiation of hydrocarbons in the presence of PH3 or H2S. He discussed some of the chemical rules which can been derived, and the applicability of these results to the case of Jupiter and Saturn.
The search for those organics in the atmosphere of the outer planets by remote sensing technique requires the availability of their spectral data, in particular in the IR range. V.A. Basiuk has used semi empirical method to determine IR spectra of various complex N-organics. His results shows the importance of such a tool for exobiological applications.
T. Owen (USA) discussed the question of the origin and evolution of Titans atmosphere, approached through the new isotopic data and presented some very new observational data related to the observation of icy satellites and Titan. The isotopic enrichments in 15N and 18O indicates that the present atmosphere is still only a small fraction of total amount of volatiles outgassed. On the contrary the normal 13C/12C value supports the existence of an hydrocarbon reservoir . The new IR spectra of the surface of Ganymede and other icy satellites of Jupiter strongly suggest the presence of complex organics, tholins with a high concentration of CN groups. The observation of Titan in the near IR provides good windows to observe its surface. The recent data suggest the presence of silicate and organics.
The presence of organics on Titans surface is also supported by other series of near IR observation of Titan, as presented by A. Coustenis (France). However, she also reported the potential detection of water ice, not reported by T. Owen.
The formation of organics on Titan may involve many processes. A comparative study performed by S. Ramirez (Mexico & France) on possible organic syntheses in Titans troposphere by corona and lightning discharges, compared to high-energy atmospheric processes was presented by R. Navarro-Gonzalez (Mexico). The results show that some organics, specifically produced by high pressure processes could be used as tracers for corona and lightning activity on Titan. The possibility of electrical activity in the low atmosphere was also reviewed in detail by R. Navarro-Gonzalez (Mexico). In that aspect, the presence of condensed HCN on Titans aerosols could play a key role in generating electrification in the aerosols layers by thermoelectric effects in the cold troposphere of Titan.
Search for organics by remote sensing techniques in Titans atmosphere requires the availability of fully calibrated spectra. V. Vuitton (France) presented the last results obtained on the IR and UV spectra of organics of interest for Titan polyynes with 4, 6 and 8 C atoms. Those are now available, upon request, on the LISA data base.
Organics are also present on Titan in the aerosol phase. Titans tholins obtained in the laboratory are supposed to be good analogues of these aerosols. P. Coll (France) in his presentation entitled everything you always wanted to know about Titans tholins, (but were afraid to ask) reviewed our current knowledge on Titans tholins and presented the very recent results, including optical properties, obtained from tholins which can be considered as the best analogues of Titans aerosols available today.
Finally, B.N. Khare (USA) reviewed on a comparative way the properties of the different solid organic matter which are present in the outer solar system, through the properties of their laboratory analogues, showing the very large variety of complex organics which can be expected in the outer solar system, due to the large variety of different environments.
All presentation were the source of many discussions, inside as well as outside the conference room. This event was very successful and the covered topics appears to be always of very great interest. It is obvious that many new data should be available in this field within 2 years from now. Thus, a 2002 COSPAR event covering this field has been proposed by R. Navarro-Gonzalez, and accepted by Scientific Commission F during its open business meeting.
Franois Raulin and Kensei Kobayashi
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Trieste Meeting : Impression of Trieste 2000
As a first time attendee at a Trieste Conference, I arrived in a mild state of excitement with my exuberant Greek-American colleague Aristotel Pappelis and his charming wife Katherine, for the Sixth Trieste Conference on Chemical Evolution entitled FIRST STEPS IN THE ORIGIN OF LIFE IN THE UNIVERSE.
Already a bustling seaport in ancient Roman times, Trieste is a unique city with an international flavor on the northern tip of the Adriatic Sea.
It was here that the Irishman James Joyce and other artists helped to usher in modern culture at the beginning of the 20th Century, and it was also here that the Pakistani physicist Abdus-Salam helped to bring to fruition the Standard Model of Particle Physics by co-inventing (along with Steven Weinberg) the Electroweak Theory uniting electromagnetism and the weak nuclear force in the latter part of the same century.
At the Adriatico Hotel, the conference site, I ran into some old friends including Bill Collins, Romeu Guimaraes, Antonio Lazcano, Koichiro Matsuno, and Bill Schopf, and I met a bevy of new friends including Herrick Baltscheffsky, Graham Cairns-Smith, Mohindra Chadha, Julian Chela-Flores, John Corliss, Jamal Islam, Mikhail Kritsky, Abel Mendez-Torres, Rafael Navarro-Gonzalez, Martino Rizzoti, Jane Schopf, Joseph Seckbach, Tahir Shah, Everett Shock, Wang Wenqing, and Edward Whitehead. It is a great experience to meet scientists from all over the world during these scientific conferences. I find the informal friendly exchanges during the coffee breaks and meals to be just as important as hearing the speakers at the formal scientific presentations.
I have not the space here to give impressions of all the formal scientific presentations made at the conference as there were approximately 100 of them. In any case, the papers will be published later on in the conference book by Kluwer Academic Publishers.
Everyone seemed happy to see and shake hands with Stanley Miller, who gave a fascinating lecture on the possibility that peptide nucleic acids (PNAs) were a precursor to the RNA World.
There were some sharp verbal exchanges at the ends of some of the oral presentations, but this is to be expected. The origin-of-life field is, after all, an area of science where no one has really yet managed to PROVE how life arose, and everyone has his or her own theory, potentially equally valid and contentiously argued, somewhat like politics.
Schopf presented a deeply thought-provoking public lecture on Ancient Life on Mars and Earth. The conclusions: We are sure that there was ancient life on Earth. We are not at all sure that there was ancient life on Mars.
Perhaps we should send some brave souls there in a rocket ship to find out once and for all the answer to this very important question. Alas, we are not going to find irrigation canals, little green men, or succulent vegetables on Mars, which is too bad because it would have been fun and it would have eased our Earthly loneliness in this outreach of the galaxy.
Mohindra Chadha showed some wonderful photographs from his albums of memorable scenes from meetings past
I really enjoyed the moving picture slides that many of the speakers projected from their laptop computers. Letters would come dancing onto the screen from different directions. Images would dissolve into a thousand little squares. Can three dimensional holographic projections be far behind?
All in all, the now triannual Trieste Conference is an excellent, smaller, more intimate counterpoint to the larger, more sprawling triannual ISSOL Conference.
I had such a good time at Trieste 2000 that I definitely plan, if invited, to come back to Trieste in 2003.
Peter Bahn
Bahn Biotechnology Co.
RR2 Box 239A
Mt. Vernon, Illinois 62864
USA
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Message to all ISSOLians
Dear ISSOLians,
As you may
all know from this new Millenium on every new member of our Society will get a
T-shirt as a little welcome. We would like to inform you that you will also
have the opportunity to get such a T-shirt for only 10 US$ (plus mailing cost)
or equivalent European currency. Please contact me if you are interested in
such a T-shirt. It is available in S,M,L or XL.
By wearing
the T-shirt you will help to make our Society known and disseminate the ideas
of what ISSOL means.
It would be great if you will all weare such a T-shirt on our next Triennal meetng in Mexico.
Best wishes,
Gerda Horneck, Secretary
Message to European ISSOLians
Dear ISSOL'ians,
It is appropriate for the new Millenium that you will have the opportunity to pay your dues in Euros. In the past it could be very complicated for European members to pay their dues, and international banking costs were sometimes very high. Because the new Secretary of our Society is also a European member we decided to open a new account in Europe. To avoid bank charges it would be the best if you will make a direct money transfer to this account, so that most of your fees will be available to support young scientists participating in ISSOL's triennial meetings. I would also take the opportunity to remind you to pay dues punctually because only our dues guarantee the growth and the vitality of the Society and the field. This year, dues responsibility was transferred to the Treasurer's office and required setting up new accounting procedures. We are running three months behind in sending out dues notices, but they are now in the mail with a November 1 deadline, and next year we will be back on schedule with a summer mailing.
Thank you very much,
| account holder: | Gerda Horneck | bank: | Kreissparkasse Koeln | bank code: | 370 501 98 | account number: | 107 868 38 26 |
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Starting with this issue, the list of the new members of ISSOL will be systematically published in the ISSOL newsletter. several colleagues have joined our Society recently. Welcome to these new ISSOLians :
|
New member |
Country |
Sponsor |
Sponsor |
|
Dr. James D. Hodge, Lodestone Technologies, Ltd. |
USA |
Dr. David Deamer |
Dr. Gerda Horneck |
|
Dr. Natalia B. Gontareva, University of St. Petersburg |
RUSSIA |
Dr. Jrgen Schmidt |
Prof. G. von Kiedrowski |
|
Dr. David L. Abel, |
USA |
Dr. Hyman Hartman |
Dr. Doron Lancet |
|
Dr. Paul Klee Strother, |
USA |
Dr. Stephen Mojzsis |
Dr. Roger Buick |
|
Prof. Robert E. Blankenship, Arizona State University |
USA |
Dr. John Cronin |
Dr. Sandra Pizzarello |
|
Dr. Joan M. Bernhard, University of Carolina |
USA |
Dr. Sam Bowser |
Dr. James Ferris |
|
Dr. James E. Dickens, |
USA |
Dr. Susan Leschine |
Dr. William Irvine |
|
Dr. Sofija I. Vujosevic, |
Serbia |
Prof. Ivan G. Draganic |
Prof. Vesna Niketic |
|
Dr. Dir Schulze-Makuch, University of Texas at El Paso |
USA |
Dr. Vladimir Kompanichenko |
Prof. William Schopf |
|
Dr. Marco Franci, |
ITALY |
Prof. Enzo Gallori |
Prof. Martino Rizzotti |
|
Prof. Satoru Nakashima, |
JAPAN |
Dr. Kensei Kobayashi |
Dr. Akira Shimoyama |
|
Dr. Dai Shiota, |
JAPAN |
Dr. Kensei Kobayashi |
Dr. Akira Shimoyama |
|
Dr. Laurent Boiteau, |
FRANCE |
Prof. Francois Raulin |
Prof. Auguste Commeyras |
|
Dr. Hiroshi Naraoka, |
JAPAN |
Dr. Kaoru Harada |
Dr. Akihiko Shimada |
|
Prof. Yi-Jehng Kuan, |
TAIWAN |
Prof. William Schopf |
Prof. Stanley Miller |
|
Mr. Jan Toporski, |
UK |
Dr. Gerda Horneck |
Prof. Pascale Ehrenfreund |
|
Mrs. Verena Starke, |
GERMANY |
Prof. William Schopf |
Dr. Gerda Horneck |
|
Dr. Alvaro Moreno, |
SPAIN |
Dr. Juli Pereto |
Prof. Antonio Laczano |
|
Prof.
Peter A. Nielsen, |
USA |
Prof. Antonio Laczano |
Dr. James Ferris |
|
|
|
|
|
|
Dr. James
H. Scott, |
USA |
Dr. Peter J. Gogarten |
Prof. Antonio Laczano |
|
Prof.
Nicolas Glansdorff, |
BELGIUM |
Prof. Antonio Laczano |
Dr. Christan de Duve |
|
Dr. David Ross, |
USA |
Dr. Bernd Simoneit |
Dr. Keith Kvenvolden |
|
Dr. Rajeshwar P. Sinha, University of Erlangen |
GERMANY |
Prof. Wolfram Thiemann |
Dr. Alan Schwartz |
|
Dr. Jane Shen-Schopf, University California LA |
USA |
Prof. Stanley Miller |
Prof. Antonio Laczano |
|
Prof. Aristoteles J. Pappelis, Southern Illinois University of Carbondale |
USA |
Dr. Peter R. Bahn |
Prof. Antonio Laczano |
|
Dr.
Pamela Gales Conrad, |
USA |
Dr. Ken Nealson |
Dr. Gene McDonald |
|
Prof. Pascale Ehrenfreund, Leiden Observatory |
THE NETHERLANDS |
Dr. Jeff Bada |
Dr. Alan Schwartz |
|
Dr. Maya Fishkis, |
USA |
|
|
|
Dr. David W. Koerner, University of Pennsylvania |
USA |
|
|
|
Dr. Uwe Meierhenrich, University of Bremen |
GERMANY |
Prof. Wolfram Thiemann |
Prof. Clifford Matthews |
|
Dr. Radu
Popa, |
USA |
|
|
|
Dr.
Michael C. Storrie-lombardi, |
USA |
|
|
|
Dr.
Frances Westall, |
USA |
Prof. Heinrich Holland
|
Dr. Antonio Lazcano |
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Reexamination on the Analytical Method of Phosphate:
Reply to Problems with Phosphate Method by Wang Kong-Jiang
In ISSOL Newsletter, Vol 25(2) Summer 1998, p.21, Wang Kong-Jiang criticized the method for the analysis of phosphate and polyphosphates in the paper Volcanic Production of Polyphosphate ........ [Nature 351, 516-519 (1991)]. His claim is that phospho-molybdate method not only detect pyrophosphate and tripolyphosphate but the color development of pyrophosphate is also similar to that of orthophosphate.
Our group had checked several times about the phospho-molybdate method before starting the analysis of volcanic polyphosphate. The results showed that pyrophosphate did not show the development of color with the phospho-molybdate method and that the color only developed by the phospho-molybdate reaction after hydrolysis of pyrophosphate. The color strength increased with the hydrolysis time and the final strength of color corresponded to twice as high as the initial molar concentration of pyrophosphate. Therefore, I believe he must have mistaken something in his experiments.
I happened to meet him in the ISSOL99 meeting at San Diego. I discussed with him about this problem, and explained to him about the our old experimental results. But, he had never agreed. Then, we made a promise to check again this problem in each laboratory.
My new experiments were carried out as follows:
#1. A 1 mM aqueous solution of penta-sodium tripolyphosphate anhydrous, Na5P3O10 (from SIGMA, practical grade: 90-95%) was prepared with cold water and it was immediately neutralized (pH 6.62) with 5N hydrochloric acid.
#2. A 3/2 mM aqueous solution of potassium pyrophosphate, K4P2O5 (from Wako Chem. Co., Japan) was prepared with cold water and it was immediately neutralized (pH 6.53) with 5N hydrochloric acid.
#3. An 3 mM aqueous solution of KH2PO4 (from Wako Chem. Co., Japan) was prepared.
Hydrolysis procedure of polyphosphate before the reaction for the analysis:
P-P-P ; 1ml of #1 + 2ml of water + 3ml of 2N H2SO4 : 0.5 mM of P
P-P ; 1ml of #2 + 2ml of water + 3ml of 2N H2SO4 : 0.5 mM of P
P ; 1ml of #3 + 2ml of water + 3ml of 2N H2SO4 : 0.5 mM of P
Mix ; Mix of each 1ml of #1, #2 and #3 + 3ml of 2N H2SO4 : 1.5 mM of P
These solutions were heated at 80C.
The reactions were performed by the method of Chen et al..
The experimental values (absorption at 820 nm) are given in the Table.
|
Hydrolysis Time |
0 |
15 |
30 |
1h |
2h |
3.5h |
6h |
|
P-P-P |
0.041 |
0.261 |
0.451 |
0.543 |
0.582 |
0.562 |
0.639 |
|
P-P |
0.069 |
0.351 |
0.481 |
0.630 |
0.650 |
0.660 |
0.690 |
|
P |
0.651 |
0.658 |
0.660 |
0.690 |
0.693 |
0.671 |
0.710 |
|
Sum |
0.761 |
1.297 |
1.592 |
1.863 |
1.925 |
1.893 |
2.039 |
|
Mix |
0.799 |
1.355 |
1.604 |
1.901 |
1.892 |
1.960 |
2.090 |
The absorption values in the table shows that
(1)P-P-P and P-P do not develop color before hydrolysis and the color gradually increase with the hydrolysis time, and finally the both colors come to the same values as that of P within the experimental errors.
(2)Sum of P-P-P, P-P and P are almost the same as Mix within the experimental errors. This means that there do not exist the mutual interferences between orthophosphate and oligo-phosphates which Wang Kong-Jiang claim.
Conclusions and Remarks:
(1) It is clear that Wang Kong-Jiang made a mistake.
(2) His mistake probably would have originated to the hydrolysis of tri-phosphate and pyrophosphate before the analysis, which he was not concerned about. Polyphosphates easily hydrolyze even in a weakly alkaline solution at a room temperature.
(3) Volcanic gas is very difficult work to collect. So, the analysis is required to perform with a very limited quantity. I think that the method by Chen et al., which was developed for Microdetermination of Phosphorus is the most excellent method for the present problems.
Yukio Yamagata
Laboratory of Chemical Evolution
1408, 15-60 Showeimachi
Kanazawa, Ishikawa 920-0846
JAPAN
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RIBS : The Research Initiative on Bahamian Stromatolites
The goal of our research is to investigate the role of microbes in early lithification of stromatolites forming in open marine environments equivalent to those of many Precambrian platforms. Our studies have shown that growth of Bahamian stromatolites represents a dynamic balance between sediment accretion and lithification of microbial mats. Lithification depends on two fundamentally important microbial processes: photosynthetic production by cyanobacteria and heterotrophic respiration by bacteria. A laminated microstructure is formed by precipitating laterally continuous sheets of microcrystalline carbonate in surface biofilms at frequent episodic intervals. In some cases, thicker layers of fused grains form below the biofilms in response to the microboring activities of coccoid cyanobacteria and precipitation, likely resulting from heterotrophic degradation of polymer in bore holes. Preservation of lithified layers at depth creates a laminated fabric.
Our results contrast with reports that eukaryotic algae are essential for the binding and trapping of coarse grained sediment and that early lithification in modern marine stromatolites is primarily an abiotic process of submarine cementation. In addition, although previous work has documented bacterial precipitation of micrite on the sheaths of dead cyanobacteria in the aphotic zone of laminated microbial mats in tidal flats, these mats do not form fully lithified laminae and stromatolitic buildups. Our evidence argues that growth of laminated microbial structures with topographic relief, such as those that dominated the fossil record for three billion years, depends on early lithification of surface mats. This lithification process occurs, at least in part, by decomposition of an amorphous matrix of bacterial exopolymer (not sheath material) in the photic zone across the stromatolite surface. Similar processes (i.e. precipitation occurs within the amorphous exopolymer matrix of biofilms, rather than on cyanobacterial sheaths), offer an additional mechanism to account for the paucity of preserved microfossils in Precambrian stromatolites, which is typically ascribed to recrystallization and/or rapid degradation of sheaths. The potential role that climax microbial communities, functionally equivalent to the endolithic coccoid cyanobacteria in modern marine stromatolites, may have played in the lithification of ancient stromatolites remains to be evaluated.
Reid, R.P., Visscher, P.T., Decho, A.W., Stolz, J.F., Bebout, B.M., Dupraz, C., Macintyre, I.G., Pinckney, J., Paerl, H.W. Prufert-Bebout, L., Steppe, T.F., DesMarais, D.J., 2000, The role of microbes in accretion, lamination and lithification in modern marine stromatolites. Nature 406:989-992.
Reid R.P. and Macintyre, I.G., 2000, Microboring versus recrystallization: further insight into the micritization process. J. Sedimentary Research, 70: 24-28.
Reid, R.P., Macintyre, I.G., Steneck,R., 1999, A microbialite/algal ridge fringing reef complex, Highborne Cay, Bahamas. Atoll Research Bulletin 466: 1-18.
Decho, A.W. 1999. Microbial Biofilms in Intertidal Systems: An Overview. Continental Shelf Res. (in press)
Macintyre, I.G., Prufert-Bebout, L. and Reid, R.P., 2000, The role of endolithic cyanobacteria in the formation of lithified laminae in Bahamian stromatolites. Sedimentology (in press).
Visscher, P.T., Gritzer, R.F., Leadbetter, E.R.. 1999. Low-molecular weight sulfonates: a major substrate for sulfate reducers in marine microbial mats. Applied and Environmental Microbiology, 65: 3272-3278.
Visscher, P.T., Reid, R.P. and Bebout, B.M., 2000, Microscale observations of sulfate reduction: correlation of microbial activity with lithified micritic laminae in modern marine stromatolites. Geology (in press).
Visscher, P.T., Reid, R.P., Bebout, B.M., Hoeft, S.E., Macintyre, I.G., and Thompson, J. Jr. 1998. Formation of lithified micritic laminae in modern marine stromatolites (Bahamas): the role of sulfur cycling. American
Mineralogist 83:1482-1491.
RIBS Public Web site: http://mgg.rsmas.miami.edu/groups/geomic/RIBS/index.html
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