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4. CARBON CAPTURE AND STORAGE (CCS) Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
Over time it has become apparent that the increase in the CO2 concentration of the atmosphere, induced by anthropogenic activities, was and is continuing to provoke global warming, sea-level rise, ocean acidification and potentially global health issues (see Section 3). Concerns over these and other consequences of anthropogenic carbon emissions have led many to call for a global effort to attenuate
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5. THE FUTURE Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
We wrote this Geochemical Perspectives in the fall of 2022. This was a curious time. During the summer of 2022 the world experienced some of the most unusual weather in years. Pakistan has experienced catastrophic floods. Much of Southern Europe experienced droughts more severe than seen in over a century. A heat-wave in the western United States during the fall of 2022 broke all-time temperature records
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CARBON CAPTURE AND STORAGE: FROM GLOBAL CYCLES TO GLOBAL SOLUTIONS Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
Anthropogenic carbon emissions have overwhelmed the natural carbon cycle, leading to a dramatic increase in atmospheric CO2 concentration. The rate of this increase may be unprecedented in Earth’s history and is leading to a substantial increase in global temperatures, ocean acidification, sea level rise and potentially human health challenges. In this Geochemical Perspectives we review the natural
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1. INTRODUCTION Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
We have in the past thought that our writing should always focus on our science. In part because we always have so much science to share and because this is what we have in common with our readers − the desire to solve some of the great questions and challenges of our world. Our opinions began to change somewhat at the 2013 Goldschmidt meeting in Florence. At a bar across from the Medici Chapel, over
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2. THE GLOBAL CARBON CYCLE AND CLIMATE Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
The transfer of carbon among the various reservoirs of the Earth both influences the global climate and makes possible life itself. The relative size of the major carbon reservoirs is shown in Figure 2.1. The atmosphere is a relatively small carbon reservoir. In pre-industrial times it contained roughly 600 gigatons of carbon, C. This has increased to approximately 900 gigatons of carbon since that
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3. ANTHROPOGENIC INFLUENCES Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
The natural carbon cycle described in the last section has been greatly influenced by human activity. Human intervention in the global carbon cycle is so large that it is often referred to as a new geologic epoch, “The Anthropocene” (Kolbert, 2011; Crutzen 2002). This epoch, however, has not yet been officially approved as a subdivision of geologic time.The beginning of Anthropocene is debated widely
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INDEX Geochem. Perspect. (IF 3.8) Pub Date : 2023-10-01 Eric H. Oelkers, Sigurdur R. Gislason
Abstract not available
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A JOURNEY IN NOBLE GAS COSMOCHEMISTRY AND GEOCHEMISTRY Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
I started my journey in science by studying noble gases implanted by the solar wind in dust grains on the surface of the Moon, and with many colleagues I have studied solar wind implanted noble gases in natural and artificial samples throughout my career, the latter exposed primarily by the Genesis space mission. Major questions are what noble gases in the solar wind can tell us about the present and
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6. CONCLUDING REMARKS Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Looking at programmes of geo- and cosmochemistry meetings, I am always impressed by how much science can be illuminated by a single group of elements – the noble gases. I have covered a very small part of this in these pages, but especially at dedicated noble gas meetings like the DINGUE series, I am always amazed at what colleagues are working on that I had no idea about. This fascinating aspect is
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DEDICATION Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
For Catherinewith whom I share my life since my graduate student days and whose love, inspiration and support I could not be without.
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PREFACE Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
A few years ago, Janne Blichert-Toft asked me to review a manuscript by Bernard Marty that became a volume of Geochemical Perspectives, describing his career and the contributions of his group at the CRPG in Nancy to the geochemistry of the “atmophile” elements H, C, N, and the noble gases (Marty, 2020). I very much enjoyed this reviewing task. It allowed me to get even better insight into the career
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ACKNOWLEDGEMENTS Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
As is probably the case with almost every scientist, my path has been shaped by numerous colleagues, mentors and students. First I would like to highlight six persons who have been particularly important to me along the way.Peter Signer was by far the most important and influential person in my scientific life. His attitude as my supervisor during my graduate studies is aptly described with the German
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1. HOW – RATHER FORTUITOUSLY – I BECAME A NOBLE GAS COSMOCHEMIST Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
On January 3rd, 1976, I returned to Switzerland after a 15 month sojourn in South America, mostly spent in Guayaquil, Ecuador, but also by traveling around the continent, including an unforgettable trip to the Galapagos Islands. Two and a half years earlier, I had obtained my diploma in Physics (today we would call this a Master’s degree) at the Swiss Federal Institute of Technology in Zürich (known
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2. NOBLE GASES FROM THE SUN Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
The importance of noble gases in the Earth and Planetary sciences has been excellently explained in two previous volumes of the Geochemical Perspectives series by Manuel Moreira and Bernard Marty (Moreira, 2013; Marty, 2020). As Manuel explains, they are geochemical tracers par excellence because they are chemically (almost) inert and thus unaltered by chemical and biological reactions. They are also
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3. NOBLE GAS (AND OTHER) STUDIES ON METEORITES AND OTHER SAMPLES FROM FAR AWAY Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Let me come back one more time to my early days in science. As described in the previous section, my scientific focus during my doctoral studies was almost exclusively on lunar samples and their noble gases. Only in passing did I realise that nature also provides us with other interesting matter from beyond our Earth. My knowledge about meteorites and their noble gases in particular tended towards
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4. NOBLE GASES IN TERRESTRIAL ROCKS Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
As noted in the introduction to Section 3, in the early- to mid-1980s I not only took my first steps away from solely studying lunar samples to becoming a meteoriticist, but also developed, more or less in parallel, an interest in noble gases (and radionuclides) in terrestrial samples. For a physicist with a meagre (to say the least) background in geology, this naturally required extensive collaboration
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5. NOBLE GASES IN WATER – THE COLLABORATION WITH EAWAG Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Let me turn back the clock one last time, to the year 1986. Rolf Kipfer, better known to many as RoKi, with his fresh ETH Diploma in Geophysics, was about to start his doctoral thesis in Peter Signer’s group. We had some good ideas for Rolf, but no mature project yet. Coincidentally, around that time, Thomas (Tommy) Gold at Cornell University approached Peter with his theory of an abiogenic origin
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LIST OF ACRONYMS Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Abstract not available
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4. NOBLE GASES IN TERRESTRIAL ROCKS Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
As noted in the introduction to Section 3, in the early- to mid-1980s I not only took my first steps away from solely studying lunar samples to becoming a meteoriticist, but also developed, more or less in parallel, an interest in noble gases (and radionuclides) in terrestrial samples. For a physicist with a meagre (to say the least) background in geology, this naturally required extensive collaboration
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3. NOBLE GAS (AND OTHER) STUDIES ON METEORITES AND OTHER SAMPLES FROM FAR AWAY Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Let me come back one more time to my early days in science. As described in the previous section, my scientific focus during my doctoral studies was almost exclusively on lunar samples and their noble gases. Only in passing did I realise that nature also provides us with other interesting matter from beyond our Earth. My knowledge about meteorites and their noble gases in particular tended towards
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2. NOBLE GASES FROM THE SUN Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
The importance of noble gases in the Earth and Planetary sciences has been excellently explained in two previous volumes of the Geochemical Perspectives series by Manuel Moreira and Bernard Marty (Moreira, 2013; Marty, 2020). As Manuel explains, they are geochemical tracers par excellence because they are chemically (almost) inert and thus unaltered by chemical and biological reactions. They are also
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1. HOW – RATHER FORTUITOUSLY – I BECAME A NOBLE GAS COSMOCHEMIST Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
On January 3rd, 1976, I returned to Switzerland after a 15 month sojourn in South America, mostly spent in Guayaquil, Ecuador, but also by traveling around the continent, including an unforgettable trip to the Galapagos Islands. Two and a half years earlier, I had obtained my diploma in Physics (today we would call this a Master’s degree) at the Swiss Federal Institute of Technology in Zürich (known
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5. NOBLE GASES IN WATER – THE COLLABORATION WITH EAWAG Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Let me turn back the clock one last time, to the year 1986. Rolf Kipfer, better known to many as RoKi, with his fresh ETH Diploma in Geophysics, was about to start his doctoral thesis in Peter Signer’s group. We had some good ideas for Rolf, but no mature project yet. Coincidentally, around that time, Thomas (Tommy) Gold at Cornell University approached Peter with his theory of an abiogenic origin
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LIST OF ACRONYMS Geochem. Perspect. (IF 3.8) Pub Date : 2023-04-01 Rainer Wieler
Abstract not available
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1. INTRODUCTION Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
I was born on August 10, 1954, in Amroha, an ancient little town located some 130 km east of Delhi within the heart of the Indo-Gangetic Plain. The community my family is a part of is called Sadat-e-Amroha (Syeds of Amroha). Traditionally, this community has been quite conservative as it claims lineage to Prophet Muhammad through his daughter Fatima, a.k.a. Syeda (from which ‘Syed’, the first part
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5. SEASONAL ANOXIA OVER THE WESTERN CONTINENTAL SHELF OF INDIA Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
In addition to the perennial ODZ in the open ocean, anoxic conditions also develop seasonally over the western Indian continental shelf. This phenomenon was first discovered in the 1950s by Karl Banse who came to India in 1958 to pursue research on tropical plankton. He was then a young man, having obtained a Ph.D. in Oceanography/Zoology from University of Kiel in 1955 followed by a post-doc at Institut
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9. THE TERRESTRIAL CONNECTION Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
The National Academy of Sciences of the USA organised a Symposium on Nutrient Over-Enrichment in Coastal Waters in October 2000 in Washington, D.C. This was a fairly large meeting, which I also attended. Christine Todd Whitman, the then Governor of New Jersey, inaugurated the Symposium. I remember her because in her inaugural address she jokingly questioned why the area of the infamous dead zone in
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2. ANOXIA IN THE OPEN OCEAN AND ANOMALOUS LOCATION OF OXYGEN DEFICIENT ZONES IN THE INDIAN OCEAN Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
One of the main goals of the Challenger Expedition was “to investigate the distribution of organic life at different depths and on the deep seafloor”. This was because, well into the 19th century, many people – prominent among whom was the British naturalist Edward Forbes (1815–1854) – had believed that the deep sea was anoxic and, consequently, azoic (Anderson and Rice, 2006). The Challenger expedition
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3. NITROGEN CYCLING IN OPEN OCEAN ODZS Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
Heterotrophic organisms derive energy by oxidising organic matter produced by autotrophs. There are a number of chemical species dissolved in seawater that may serve as electron acceptors (oxidants) for this purpose. The most important of these are oxygen, nitrate (and other oxidised forms of nitrogen), manganese (IV), iron (III) and sulfate. The energy gained by the heterotrophs using these electron
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ACKNOWLEDGEMENTS Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
I wish to express my sincere gratitude to all my colleagues and co-workers, too many to name individually, who have contributed to the generation of information summarised here. I am grateful to the Directors of NIO and the Director-Generals of CSIR who I worked under, as well as the funding agencies (especially the Ministry of Earth Sciences) for their support and encouragement throughout my career
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ANOXIA-RELATED BIOGEOCHEMISTRY OF NORTH INDIAN OCEAN Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
This article provides a brief account of my early life and career, and a more detailed description of the contributions of the groups with which I have been associated to the biogeochemistry of the North Indian Ocean, especially nitrogen cycling in oxygen deficient waters.Some of the most intense oxygen depletion in the water column in the open ocean occurs at mid-depths in the two northern basins
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4. REDOX SENSITIVE ELEMENTS OTHER THAN NITROGEN Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
As stated earlier, in addition to nitrogen, several other polyvalent elements also undergo redox transformations in anoxic waters (Table 1). Studies in the Arabian Sea undertaken prior to JGOFS had focussed on manganese (Mn), iron (Fe) and cerium (Ce) (Saager et al., 1989; German and Elderfield, 1990). These authors observed concentration maxima in dissolved Mn, Fe and Ce (operationally defined as
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6. GLOBAL EFFORT TO ASSESS OCEAN DEOXYGENATION: TRENDS IN THE INDIAN OCEAN Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
Human activities are affecting oxygen distribution in the ocean in two major ways (Keeling et al., 2010; Breitburg et al., 2018; Naqvi, 2020). (1) Rising levels of greenhouse gases in the atmosphere are also causing ocean warming, with as much as 93 % of the extra energy being retained by the planet going into the oceans. Warming may affect the oxygen balance of subsurface waters through a decrease
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7. SOME OUTSTANDING ISSUES CONCERNING INDIAN OCEAN’S OXYGEN DEFICIENT ZONES Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
Despite huge advances over the past few decades in our understanding of the biogeochemistry of ODZs, there are still a couple of fundamental, inter-related questions that remain to be satisfactorily answered, with one of them more specific to the North Indian Ocean. (1) Can substantial combined nitrogen loss through heterotrophic denitrification and anammox occur in the presence of oxygen in traces
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8. OCEANOGRAPHY OF MARGINAL SEAS OF THE NORTHWEST INDIAN OCEAN Geochem. Perspect. (IF 3.8) Pub Date : 2022-10-01 S. Wajih A. Naqvi
The Northwestern Indian Ocean contains two marginal seas: the Red Sea and the Persian Gulf. Located in a highly arid region, these seas experience negative water balance (large excess of evaporation over precipitation and river runoff) resulting in very high salinities and Mediterranean-type (anti-estuarine) circulation i.e. net flow of fresher seawater into these basins close to the surface and outflow
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1. THE PROBLEM Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
Man lives on the earth, and although his Kingdom is not of this world, this seems insufficient reason to neglect our relation with our foster planet, which has been, and probably will remain, the sole abode of mankind. As Henderson (1913) pointed out in his masterly essay The Fitness of the Environment,1 current opinion, up to the birth of natural sciences was that the earth was created as our playground
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APPENDIX Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
Left page: [Quotations from the Bible (see transcription of the manuscript) and 2 D version of a 3 D tetrahedron or triangular pyramid, to depict the oxidation and reduction of carbon and nitrogen compounds.]Joshua speaks to the tribes of Joseph (Joshua 17:18) but the mountain shall be thine; for it is a wood and thou shalt cut it down: and the outgoings of it shall be thine.1Genesis 1:28 Be fruitful
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FOREWORD Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
Lourens Baas Becking is a pivotal figure in the history of microbial ecology and geobiology, having coined the term “Geobiologie” in the title of his 1934 opus (Geobiologie ofinleiding tot de milieukunde). This work has been translated into English (Baas Becking, 2016), so everyone now can read of Baas Becking’s contributions and see for themselves the context of his most famous proposition “Everything
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PREFACE Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
I wrote a book about the earth and man. He was always there as a hunting dog on the trail, restless, enthusiastic, with impromptu promptings, which helped me. For example, I wrote about a city with its energy production as an organism. He gave me to read Ezekiel 27, which describes the riches of Tyrus, and when I spoke of the devastation that man wreaks on earth, he showed me places from Isaiah, and
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GEOBIOLOGY Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
Lourens Baas Becking (1895-1963) was a Dutch plant physiologist, trained in the Botanical Laboratory of Utrecht University. After graduating in 1919, he worked in America at Stanford University, where he obtained his Doctor’s degree in 1921. From 1928, he was Herzstein Professor of Biology and Director of the Jacques Loeb Physiological Laboratory at the Hopkins Marine Station in Palo Alto. In 1931
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2. THE EARTH Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
Astronomists and geologists agree that this universe suffered a great conflagration about 2,000,000,000,0000 years (two thousand million years) ago. Umbgrove (1942) has dealt with these and called allied matter in his book The Pulse of Earth.1 Our planetary system seems to have originated in this epoch and, according to all probability, the earth, together with the other planets, was torn from the
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3. THE MILIEU Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
The limits of the milieu for a certain organism strictly pertain to a certain stage in its development. The milieu for a larva and for an imago may be different. Still, we might consider an integration of the boundaries for a certain stage, as long as that stage requires a constant milieu. Geobiologically this is an organism distinct from another developmental stage. Potential milieu is limited by
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4. THE ORGANISMS Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
If we consider the milieu as the stage of the life drama (Lotka), the living beings are the actors and the drama consists, like any proper ‘roman familial’, “of the relation between these actors with their environment and with another.”1 If we want to consider living things from this point of view, we are much more concerned with their activities and with their composition as with their form. Our problem
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5. INFLUENCE OF THE MILIEU UPON THE ORGANISMS Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
The living mass of one organism, or a population seems to increase according to a special law. The increase is often first fast, then slows down, until growth stops. There seems to be for the organism and for the population a limit which is slowly reached. Robertson compared the process to an autocatalytic reaction in which the reaction velocity dy/dt = y (a-y) in which y is the amount of substance
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6. INFLUENCE OF ORGANISMS Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
From Lavoisier (1790) we owe the rule of the indestructability of matter: “rien ne se perd, rien ne se crée”. Robert Mayer (1842) has created its analogue in energetics: the rule of the indestructibility of energy, “das Gesetz der Erhältung der Kraft”. Both rules have become to one since Einstein’s demonstration of the identity of matter and energy.Now Clausius formulated the second law of thermodynamics
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7. MUTUAL INFLUENCE Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
“Closed universes”, J. Beauverie and S. Monchal. Comptes Rendus, 195 (1932).1Coenobiosis Derx, symbiose, metabiose, pseudometabiosis.Antagonism, L. v. Luyck.M. Kiese, Klinische Wochenschrift 22, 505, 1943. Penicillin!Abraham, Cole and Porter, Raistrick.2Unicellular, all potencies (possibilities) together. Possibilities spread! Is it all redox? Is it all exchange of substances? (See Fig. 7.1).Maximal
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8. MAN AND THE TERRESTRIAL MILIEU Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
R.G. Stapledon. A Survey of the Agriculture and Waste Land of Wales, 1936, p. 9: “The toxic above all others which this nation with its large population of unemployed, its excessive wasting of energy in non-creative enterprises, and in morbid pursuits needs, is the stimulation of well organised and well planned land improvement carried into every parish of Great Britain.”W. Davies (in the above), Wales
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9. DESCRIPTION OF NATURAL MILIEU Geochem. Perspect. (IF 3.8) Pub Date : 2022-04-01 Lourens G.M. Baas Becking, Alexander J.P. Raat
Literature at Botanical Laboratory Leiden.1[Four concentric circles.]Literature at Botanical Laboratory Leiden.2Literature at Botanical Laboratory Leiden.3(Baas Becking, 1936a).[Baas Becking left this section blank.]Rhopalophylla salina, Kirby, 34.8 % salt, 1934.Gersik Puthih, island of Madura.6See literature!Freshwater floating brine.Literature L. Baas Becking. Royal Academy.7To outline the so called
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PREFACE Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
Every young scientist, who starts in a research field, builds her or his work on the experience of previous generations of scientists. We try to absorb the wisdom of those earlier generations, but with time we start to question the validity of their interpretations. Then we venture into new and unknown regions of the field, and over the years we may ourselves generate some valuable new understanding
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ACKNOWLEDGEMENTS Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
I am deeply grateful to the many master’s and PhD students, postdocs and colleagues with whom I have had the priviledge to work over many years. They have been a continuous inspiration and support and a source of new understanding and new scientific results. Together, we have shared the excitement of successful results during our work and, during the journey, we have also experienced disappointments
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SULFUR BIOGEOCHEMICAL CYCLE OF MARINE SEDIMENTS Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
Complex interactions between microbial communities and geochemical processes drive the major element cycles and control the function of marine sediments as a dynamic reservoir of organic matter. Sulfate reduction is globally the dominant pathway of anaerobic mineralisation and is the main source of sulfide. The effective re-oxidation of this sulfide at the direct or indirect expense of oxygen is a
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1. INTRODUCTION Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
My primary approach to the study of sulfur cycling has been experimental, based on the use of radiotracers and other methods to determine the rates and pathways of individual processes. The results were integrated with geochemical data and checked by simple transport reaction modelling. Often, the experimental and the modelled rates did not compare well. In an attempt to understand why, I learned to
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2. MY PERSONAL AND SCIENTIFIC HISTORY Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
This section is a personal account of my time in science and the science of my time over the past fifty years. In retrospect, I could try to describe my scientific career as well planned and structured. Yet, the truth is that major shifts in my life, both personal and professional, were directed by opportunities that showed up unexpectedly or developments that I had not foreseen. That was how I came
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3. SULFATE REDUCTION Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
The seabed is the largest anaerobic bioreactor on Earth. Ocean water contains 28 mM sulfate, which can penetrate metres down into the seabed. Dissimilatory sulfate reduction to sulfide is therefore globally the most important terminal pathway of organic matter mineralisation in the anoxic seabed. The sulfate reducing microorganisms feed on small organic molecules and H2 from which they transfer electrons
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4. SULFIDE OXIDATION Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
The oxidation of sulfide is equally important for the sulfur cycle as the reduction of sulfate. It is particularly important in coastal sediments because of the potential toxic effect of H2S to the benthic fauna or to fish. Sulfide inhibits cytochrome c oxidase in the mitochondrial respiratory chain and thereby blocks the production of ATP. Sulfide is therefore a serious environmental threat to the
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5. DYNAMICS OF INTERMEDIATE SULFUR SPECIES Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
The inorganic sulfur species, with an oxidation state intermediate between sulfide (-2) and sulfate (+6), play an important role in the sulfur cycle of marine sediments. They tend to be chemically reactive and can be utilised for the energy metabolism of a large diversity of microorganisms. They may be reduced back to sulfide in the presence of H2 or organic substrates that serve as electron donors
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6. SEDIMENT MINERALISATION PROCESSES Geochem. Perspect. (IF 3.8) Pub Date : 2021-10-01 Bo Barker Jørgensen
When viewed over a very broad time interval, from days to millions of years, the degradation rate of sediment organic matter is primarily a function of its age. This was shown clearly in an analysis by Middelburg (1989, 2019) in which the reactivity, i.e. the specific degradation rate constant, of marine organic matter was shown to be a log-log linear function (power law function) of its “initial age”