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- 저자 : Sinninghe Damsté (검색결과 2 건)
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Dessandier, Pierre-Antoine,Bonnin, Jé,rô,me,Malaizé,, Bruno,Lambert, Clé,ment,Tjallingii, Rik,Warden, Lisa,Sinninghe Damsté,, Jaap S.,Kim, Jung-Hyun Elsevier 2018 Palaeogeography, palaeoclimatology, palaeoecology Vol.496 No.-
<P><B>Abstract</B></P> <P>We analyzed a 10-m sediment core retrieved at 82 m water depth off the coast of the Tagus River (Western Iberian Margin, Portugal) to investigate a linkage between variations in benthic foraminiferal assemblages and Tagus River discharge over the last 5700 years. Benthic foraminiferal assemblages were studied at high resolution in combination with the stable carbon and oxygen isotopic composition of fossil shells of <I>Nonion scaphum</I>, bulk and molecular organic matter properties (TOC, TN, C/N ratio, δ<SUP>13</SUP>C<SUB>TOC</SUB>, δ<SUP>15</SUP>N<SUB>bulk</SUB>, and BIT index), magnetic susceptibility, and XRF analyses. Three periods of environmental changes were identified: 1) high Tagus River discharge in 5750–2200 calendar year before present (cal yr BP), 2) lower discharge characterized by intense upwelling conditions (2250–1250 cal yr BP), and 3) both intense upwelling and Tagus River discharge (1250 cal yr BP-present). The data reveal alternating intense upwelling periods, as shown by the dominance of <I>Cassidulina carinata</I>, <I>Valvulineria bradyana</I>, or <I>Bulimina marginata</I>, whereas periods of increased river discharge are indicated by increase of <I>N. scaphum</I>, <I>Ammonia beccarii</I>, and <I>Planorbulina mediterranensis</I>. The Tagus River discharge was the strongest during the first period, transporting riverine material further offshore and preventing the establishment of a mud belt on the mid-shelf (around 100 m depth). During the second period, a decrease in Tagus River discharge favored the formation of the Tagus mud belt and strongly influenced the benthic environment by creating an organic matter stock. During the third period, intense upwelling and increased Tagus River discharge were recorded by benthic foraminiferal distribution, with an increase of terrestrial elements present in the mud belt. Furthermore, our results showed that variations in benthic foraminiferal assemblages corresponded to the well-known climatic periods in the study area, such as the Roman Period, the Dark Ages, the Medieval Warm Period, and the Little Ice Age. Our study strongly suggests that benthic foraminiferal assemblages can be used as a bio-indicator to trace the influence of past river discharge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Benthic foraminifera allow the reconstruction of past Tagus River discharges. </LI> <LI> Three different periods of environmental changes have been identified. </LI> <LI> Major change is due to the Tagus mud belt onset at around 2000 yr BP. </LI> <LI> Upwelling active periods are linked with positive phases of NAO. </LI> <LI> Tagus River discharges are associated with negative phases of NAO. </LI> </UL> </P>
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Jung, Man-Young,Park, Soo-Je,Kim, So-Jeong,Kim, Jong-Geol,Sinninghe Damsté,, Jaap S.,Jeon, Che Ok,Rhee, Sung-Keun American Society for Microbiology 2014 Applied and environmental microbiology Vol.80 No.12
<P>Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e., <I>Nitrosopumilus maritimus</I> and “<I>Candidatus</I> Nitrosoarchaeum koreensis,” is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5 mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of <I>N. maritimus</I> and “<I>Ca</I>. Nitrosoarchaeum koreensis,” and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name “<I>Candidatus</I> Nitrosotenuis chungbukensis” for the ammonia-oxidizing archaeal strain MY2.</P>
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