Assuntos
Minerais/análise , Origem da Vida , Aminoácidos/metabolismo , Animais , Evolução Biológica , Catálise , Células , Cristalografia , Caulim , Modelos Químicos , Moldes GenéticosRESUMO
The Chernobyl nuclear power station accident released large quantities of vaporized radionuclides, and, to a lesser extent, mechanically released small (less than 1-10 micron) aerosol particles. The total release of radioactivity is estimated to be out of the order of 1-2 x 10(18) Bq (3-5 x 10(7) Ci) not allowing for releases of the xenon and krypton gases. The 137Cs releases of 3.8 x 10(16) Bq from Chernobyl can be compared to 1.3 x 10(18) Bq 137Cs released due to atmospheric nuclear weapons testing. Chernobyl-derived radionuclides can be used as transient tracers to study physical and biogeochemical processes. Initial measurements of fallout Chernobyl radionuclides from a time-series sediment trap at 1,071 m during June-September 1986 in the southern Black Sea are presented. The specific activities of 137Cs, 144Ce and 106Ru in the trap samples (0.5-2, 4-12 and 6-13 Bq g-1) are independent of the particle flux while their relative activities reflect their rates of scavenging in the order Ce greater than Ru greater than Cs.
Assuntos
Acidentes , Reatores Nucleares , Poluentes Radioativos da Água/análise , Poluentes da Água/análise , Europa (Continente) , Água do Mar , UcrâniaAssuntos
Carbonatos/metabolismo , Fosfatos/metabolismo , Dióxido de Silício/metabolismo , Fosfatase Alcalina/metabolismo , Aminoácidos/metabolismo , Animais , Osso e Ossos/metabolismo , Anidrases Carbônicas/metabolismo , Cartilagem/metabolismo , Fenômenos Químicos , Química , DNA , Ácido Edético , Humanos , Ligação de Hidrogênio , Matemática , Microscopia Eletrônica , Modelos Biológicos , Modelos Moleculares , Conformação Molecular , Ligação Proteica , Biossíntese de Proteínas , Especificidade da Espécie , Termodinâmica , Transcrição GênicaRESUMO
Lake Kivu, an African rift lake, contains about 50 cubic kilometers of methane (at standard temperature and pressure) in its deep water. Data resulting from two recent expeditions to the lake and a reevaluation of earlier data suggest that most of the methane was formed by bacteria from abiogenetic carbon dioxide and hydrogen, rather than being of volcanic origin or having formed from decomposing organic matter.
Assuntos
Aminoácidos , Enzimas , Relação Estrutura-Atividade , Fosfatase Alcalina , Sequência de Aminoácidos , Aminoácidos/metabolismo , Animais , Arginina , Bactérias/enzimologia , Sítios de Ligação , Bovinos , Fenômenos Químicos , Química , Cristalografia , Sistema Digestório/enzimologia , Ativação Enzimática , Enzimas/metabolismo , Ácido Graxo Sintases , Glucose , Glucosiltransferases , Lisina , Músculos/enzimologia , Pâncreas/enzimologia , Peptídeo Hidrolases , Fosfoglucomutase , Prolina , Ligação Proteica , Conformação Proteica , Coelhos , Serina , Tripsina , TripsinogênioRESUMO
Three distinct sedimentary units, which can be correlated throughout the basin, occur in cores collected from the Black Sea. Carbon-14 ages help to define the recent sedimentary history of the Black Sea.
RESUMO
Lamellar and tubular membranes and orgacnic fragments resemnbling bacterial cell walls were abundant in Black Sea sediments deposited between 3000 and 7000 years ago. This time period was marked by a gradual transition from a freshwater to a seawater environment. The resulting salinity gradient in the interstitial solutions probably promoted natural chromatography and dissolution, redeposition, and preservation of organic molecules. The preservation of organic structures may have resulted from the lack of dissolved oxygen, high concentrations of metal ions, and structural reorganization during compaction.
Assuntos
Bactérias , Parede Celular , Paleontologia , Microscopia EletrônicaRESUMO
In some calcium carbonate-bearing sandstones from the edge of the continental shelf off the northeast United States, the deltaC(13) range is from -30 and -60 per mil for both aragonite and high-magnesium calcite. The deltaC(13) of co-existing shells of Modiolus sp. is normal (+ 1.7 to -2.7 per mil). The deltaO(18) values of around + 3.5 per mil in all samples suggest deposition at temperatures around 0 degrees C. Quaternary methane oxidized either chemically or microbiologically to carbon dioxide is the probable source of carbon in these carbonates.
RESUMO
A bathymetric and geophysical survey of the Red Sea rift valley between 21 degrees 10' and 21 degrees 30'N has defined three separate pools of hot brines. The brines and their associated heavy metals are believed to be periodically discharged from the eastern side of the largest deep, Atlantis II. Cores taken from the flanks of the deeps show repetitive cycles of sedimentation of hydrous amorphous iron oxides which fill most of Atlantis II Deep.
Assuntos
Calcificação Fisiológica , Minerais , Moluscos , Aminoácidos/análise , Animais , Bicarbonatos/metabolismo , Evolução Biológica , Soluções Tampão , Cálcio/metabolismo , Carbonatos/metabolismo , Formiatos , Concentração de Íons de Hidrogênio , Hidroxilaminas , Paleontologia , Peptídeos/análise , Fosfatos/metabolismo , Proteínas/análise , Proteínas/metabolismo , UreiaAssuntos
Adenina/análise , Cromatografia por Troca Iônica , Citosina/análise , Guanina/análise , Timina/análise , Uracila/análise , Celulose , DNA/análise , Formiatos , Temperatura Alta , Pressão , RNA/análiseRESUMO
Amino acids dissolved in salt solutions may be concentrated and removed from the solution by ligand exchange on copper-Chelex 100 resin. Competing inorganic ligands do not interfere, and ion exchange with cations does not occur; thus loss of metal ion from this column is avoided. To test the potentiality of ligand exchange for chromatography, the type and nature of the dissolved amino compounds in sea water were investigated. The data revealed that the bulk of the dissolved amino compounds is present in a combined rather than a free state.
