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At least 19 recordsLinked to original sources
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Prebiotic nucleotide synthesis-demonstration of a geologically plausible pathway.

Mineral phosphate (apatite) is activated for the synthesis of nucleotides when dilute solutions containing nucleoside and ammonium oxalate are evaporated in its presence. A natural, igneous fluorapatite was found to be even more effective in nucleotide synthesis than the more soluble hydroxylapatite. The phosphorylation is considerably more efficient if urea of cyanamide is also present. Hydrolysis of solutions of cyanogen to form oxalate and urea among other products is a spontaneous process that provides a geologically plausible model for necleotide synthesis on the primitive earth.

Apatites↗
PubMed1978

Geologic implications in the distribution of endemic goiter in Colombia, South America.

A survey of 37 communities supplied by stream water and receiving iodised salt for the last 10-20 years indicates that the presence of sedimentary rocks in the watersheds of streams more closely correlates with goiter prevalence than 12 other possible causative variables. These results support the hypothesis that sedimentary rocks rich in organic matter are the main source of water-borne goitrogens.

Child↗
PubMed1979

Regional geochemical mapping and interpretation in Britain.

Regional geochemical atlases of Britain and the British North Sea prepared by the Institute of Geological Sciences are discussed with special reference to their environmental significance. Factors affecting the selection of sample types are considered, and sample preparation, analytical procedure and monitoring error discussed. Stream sediment is shown to be the optimum sample type for regional geochemistry in areas of upland Britain underlain by crystalline bedrock, although soils may provide the optimum sample medium in areas of intensive agriculture. Geochemical mapping of the continental shelf is based on superficial seabed material obtained by grab or cone dredge. Examples of geochemical maps of northern Scotland for several elements of environmental significance including Cu, Mo, Pb, and U are considered in relation to geology, topography, vegetation, land use and the chemistry of surface waters. Geochemical maps are shown to provide the best available source of information on chemical variations in bedrock, although there are many difficulties in relating geochemical or biological activity to the total trace element values. In any attempt to correlate trace element levels with disease, careful consideration must be given to factors affecting the availability and flux of the trace elements if meaningful associations are to be obtained. Geochemical maps of the North Sea indicate that the contents of Cu, Pb, Zn, Cd and Hg are uniformly low over most of the offshore area although higher concentrations occur in coastal samples. The highest concentrations of Cu, Pb and Zn occur off the Tyne estuary while the highest values for Cd and Hg occur further south.

Geography↗
PubMed2024

Illuminating the coevolution of photosynthesis and Bacteria.

Life harnessing light energy transformed the relationship between biology and Earth-bringing a massive flux of organic carbon and oxidants to Earth's surface that gave way to today's organotrophy- and respiration-dominated biosphere. However, our understanding of how life drove this transition has largely relied on the geological record; much remains unresolved due to the complexity and paucity of the genetic record tied to photosynthesis. Here, through holistic phylogenetic comparison of the bacterial domain and all photosynthetic machinery (totally spanning >10,000 genomes), we identify evolutionary congruence between three independent biological systems-bacteria, (bacterio)chlorophyll-mediated light metabolism (chlorophototrophy), and carbon fixation-and uncover their intertwined history. Our analyses uniformly mapped progenitors of extant light-metabolizing machinery (reaction centers, [bacterio]chlorophyll synthases, and magnesium-chelatases) and enzymes facilitating the Calvin-Benson-Bassham cycle (form I RuBisCO and phosphoribulokinase) to the same ancient Terrabacteria organism near the base of the bacterial domain. These phylogenies consistently showed that extant phototrophs ultimately derived light metabolism from this bacterium, the last phototroph common ancestor (LPCA). LPCA was a non-oxygen-generating (anoxygenic) phototroph that already possessed carbon fixation and two reaction centers, a type I analogous to extant forms and a primitive type II. Analyses also indicate chlorophototrophy originated before LPCA. We further reconstructed evolution of chlorophototrophs/chlorophototrophy post-LPCA, including vertical inheritance in Terrabacteria, the rise of oxygen-generating chlorophototrophy in one descendant branch near the Great Oxidation Event, and subsequent emergence of Cyanobacteria. These collectively unveil a detailed view of the coevolution of light metabolism and Bacteria having clear congruence with the geological record.

Photosynthesis↗
PubMed1978

Peptide formation in the prebiotic era: thermal condensation of glycine in fluctuating clay environments.

As geologically relevant models of prebiotic environments, systems consisting of clay, water, and amino acids were subjected to cyclic variations in temperature and water content. Fluctuations of both variables produced longer oligopeptides in higher yields than were produced by temperature fluctuations alone. The results suggest that fluctuating environments provided a favorable geological setting in which the rate and extent of chemical evolution would have been determined by the number and frequency of cycles.

Bentonite↗
PubMed1977

Chemical evolution and the evolution of the earth's crust.

It is hypothesized that there is a close relationship between the geologic evolution of the global plates of the Earth's crust and the chemical evolution of life on the Earth. Characteristics of the axes of plate spreading are discussed in relation to postulated environments conductive to the synthesis of chemical compounds thought to be important biological precursors. Likely locations for in situ measurements to test the hypothesis are identified.

Biological Evolution↗
PubMed1979

Smectite clays in Mars soil: evidence for their presence and role in Viking biology experimental results.

Various chemical, physical and geological observations indicate that smectite clays are probably the major components of the Martian soil. Satisfactory ground-based chemical simulation of the Viking biology experimental results was obtained with the smectite clays nontronite and montmorillonite when they contained iron and hydrogen as adsorbed ions. Radioactive gas was released from the medium solution used in the Viking Labeled Release (LR) experiment when interacted with the clays, at rates and quantities similar to those measured by Viking on Mars. Heating of the active clay (mixed with soluble salts) to 160 degrees C in CO2 atmosphere reduced the decomposition activity considerably, again, as was observed on Mars. The decomposition reaction in LR experiment is postulated to be iron-catalyzed formate decomposition on the clay surface. The main features of the Viking Pyrolytic Release (PR) experiment were also simulated recently (Hubbard, 1979) which the iron clays, including a relatively low '1st peak' and significant '2nd peak'. The accumulated observations on various Martian soil properties and the results of simulation experiments, thus indicate that smectite clays are major and active components of the Martian soil. It now appears that many of the results of the Viking biology experiments can be explained on the basis of their surface activity in catalysis and adsorption.

Chemical Phenomena↗
PubMed1978

Environmental considerations for the disposal of PBB-contaminated animals and wastes.

Accidental contamination of livestock feed in 1973 by polybrominated biphenyls (PBB) led to the destruction of over 30,000 animals in Michigan. Animal carcasses of mostly dairy cattle along with some beef cattle, hogs, sheep and rabbits destroyed under the Federal Food and Drug Administration guidelines were disposed on the land at an environmentally safe site in Kalkaska County, Michigan. The geology and hydrology of the disposal site on state-owned land is considered favorable for the disposal of contaminated carcasses and to prevent any migration of PBBs into ground and surface waters of the area. Materials underneath the site are predominantly sand with layers of silts and clays of glacial origin. The vertical isolation from the surface to the water table is over 90 ft, and the horizontal isolation to the privately owned properties and surface water bodies is well over 1.5 mile in all directions. The site design provides necessary safeguards for minimizing surface water infiltration into disposal trenches and maximizing the protection to the environment. A series of water wells in the direction of flow are established for monitoring groundwater quality for years to come. A 40-acre Gratiot County landfill located near St. Louis, Michigan, has received 269,000 lb of wastes containing 60 to 70% PBBs between 1971 and 1973. PBB wastes are intermixed with general refuse at various depths predominantly in the eastern half of the landfill. Phase I of the hydrogeological investigation shows that the landfill is situated immediately above the groundwater aquifer and a divide. Recently drilled test wells show traces of PBBs in the aquifer in all directions. Additional studies are planned in the near future for corrective measures and monitoring.

Animals↗
PubMed1978

Solid wastes from nuclear power production.

Radioactivity in nuclear power effluents is negligible compared to that in retained wastes to be disposed of as solids. Two basic waste categories are those for which shallow disposal is accepted and those for which more extreme isolation is desired. The latter includes "high level" wastes and others contaminated with radionuclides with the unusual combined properties of long radioactive half-life and high specific radiotoxicity. The favored method for extreme isolation is emplacement in a deep stable geologic formation. Necessary technologies for waste treatment and disposal are considered available. The present program to implement these technologies is discussed, including the waste management significance of current policy on spent nuclear fuel reprocessing. Recent difficulties with shallow disposal of waste are summarized.

Geological Phenomena↗