Global biogeochemical cycles: progress and problems

Microorganisms in soils and waters convert many synthetic organic chemicals to inorganic products. Other compounds are transformed only by cometabolism. These microbial processes may lead to environmental detoxication, the formation of new toxicants, or the biosynthesis of persistent products. Type reactions are proposed for major categories of enzymatic transformation of synthetic chemicals in soils, natural waters, and sewage. Some organic molecules are resistant to microbial attack, and explanations for the persistence of such compounds are suggested.

https://science.sciencemag.org/content/sci/211/4478/132.full.pdf

Biodegradation of Chemicals of Environmental Concern

Processes controlling the organic carbon content of open ocean sediments

A fossil Lagerstatte from the 700–750 Ma old Svanbergfjellet Formation of northeastern Spitsbergen offers a substantially enhanced view of late Proterozoic paleobiology. Fossils occur primarily as Organic-walled compressions in shales and permineralizations in chert: secondary modes of preservation include bedding-plane imprints and mineral replacements in apatite and goethite (?). The depositional setting of all fossiliferous horizons is broadly peritidal with highest taxonomic diversity occurring in shallow subtidal settings; the details of included fossil assemblages contribute to improved paleoecological resolution. The often distinct constituents of shale-and chert-hosted fossil assemblages appear to be a product of both paleoenvironment and fundamentally dissimilar taphonomic pathways, such that only forms with inferred wide ecological tolerance appear in both. Consideration of taphonomic processes also provides a variety of useful taxonomic insights, on the one hand permitting some resolution of so-called wastebasket taxa. such as Chuaria, and on the other acknowledging the taxonomic disparity that can occur in simple forms like Siphonophycus and Oscillatoriopsis. True multicellular (including coenocytic) eukaryotes are a conspicuous Component of the Svanbergfjellet assemblage: of eight distinct taxa, one can be identified as a coenobial/colonial chlorococcalean and three as filamentous siphonocladaleans (Chlorophyta). Other forms are problematic, but several show significant cell, or possibly tissue, differentiation. A review of Proterozoic multicellular organisms reveals that a coenocytic grade of organization was common among early metaphytes and supports the view (that a cellularity is a derived condition in many ‘multicellular’ lineages. Nineteen acritarch taxa are preserved in the Svanbergfjellet sediments. Ten of these show a readily identifiable ornamentation and contribute significantly to Neoproterozoic biostratigraphy; a world-wide and exclusively Late Riphean distribution of the acanthomorph Trachyhystrichosphaera aimika identifies it as a particularly valuable index fossil. The Svanbergfjellel fossil assemblage preserves a total of 63 distinct forms, of which 56 are treated taxonomically. As much as possible, principles of ‘natural’ taxonomy are applied, such that taphonomic and ontogenetic variants are declined separate taxonomy status. Major taxonomic revisions are offered for the acritarchs Trachyhystrichosphaera and Chuaria as well as for the prokaryotic-grade filaments: Cephalonyx, Cyanonema, Oscillatoriopsis, Palaeolyngbya, Rugossopsis, Siphonophycus, Tortunema, and Veteronostocale. Newly erected taxa include 7 new genera: Palaeastrum. Proterocladus, Pseudotawuia, Valkyria, Cerebrosphaera, Osculosphera and Pseudodendron; 14 new species in 12 genera: Palaestrum ***dyptocranum, Proterocladus major, Proterocladus minor, Proterocladus ***hermannae. Pseudodendron birenifera, Valkyria borealis, Cerebrosphaera buickii, Osculosphaera hyaline, Pseudodendron anteridium fullerne, Germinosphaera jankauskasii, Trachyhystrichosphaera polaris, Siphonophycus thulenema and thulenema and Digitus adumbrates 7 new combinations: Leiosphaeridia wimanii, Eoentophysalis croxfordii Cephlonyx geminatus. Oscillatoriopsis amadeus. Siphonophycus typicum, Siphonophycus solidum and Tortunema Wernadskii.

Paleobiology of the Neoproterozoic Svanbergfjellet Formation, Spitsbergen

1,4-Dioxane is classified as a probable human carcinogen. It is used as a stabilizer for chlorinated solvents, particularly, 1,1,1-trichloroethane (TCA), and it is formed as a by-product during the manufacture of polyester and various polyethoxylated compounds. Improper disposal of industrial waste and accidental solvent spills have resulted in the contamination of groundwater with 1,4-dioxane. Volatilization and sorption are not significant attenuation mechanisms due to 1,4-dioxane's complete miscibility with water. At present, advanced oxidation processes (AOPs) are the only proven technology for 1,4-dioxane treatment. 1,4-Dioxane was believed to be very resistant to both abiotic and biologically mediated degradation due to its heterocyclic structure with two ether linkages. However, recent studies have shown that 1,4-dioxane can be biodegraded as a sole carbon and energy source, and that cost-effective biological treatment processes can be developed. Future work should be oriented towards the developme...

M. Alexander

Papers

Nonbiodegradable and other racalcitrant molecules