Land cover classification of Samoylov Island and Landsat subpixel water cover of Lena River Delta, Siberia, with links to ESRI grid files

Ignoring small-scale heterogeneities in Arctic land cover may bias estimates of water, heat and carbon fluxes in large-scale climate and ecosystem models. We investigated subpixel-scale heterogeneity in CHRIS/PROBA and Landsat-7 ETM+ satellite imagery over ice-wedge polygonal tundra in the Lena Delta of Siberia, and the associated implications for evapotranspiration (ET) estimation. Field measurements were combined with aerial and satellite data to link fine-scale (0.3 m resolution) with coarse-scale (upto 30 m resolution) land cover data. A large portion of the total wet tundra (80%) and water body area (30%) appeared in the form of patches less than 0.1 ha in size, which could not be resolved with satellite data. Wet tundra and small water bodies represented about half of the total ET in summer. Their contribution was reduced to 20% in fall, during which ET rates from dry tundra were highest instead. Inclusion of subpixel-scale water bodies increased the total water surface area of the Lena Delta from 13% to 20%. The actual land/water proportions within each composite satellite pixel was best captured with Landsat data using a statistical downscaling approach, which is recommended for reliable large-scale modelling of water, heat and carbon exchange from permafrost landscapes.

(Table S1) Radiocarbon dates of organic matter from Lena Delta ice wedges

Relative to the past 2,000 years, the Arctic region has warmed significantly over the past few decades. However, the evolution of Arctic temperatures during the rest of the Holocene is less clear. Proxy reconstructions, suggest a long-term cooling trend throughout the mid- to late Holocene, whereas climate model simulations show only minor changes or even warming. Here we present a record of the oxygen isotope composition of permafrost ice wedges from the Lena River Delta in the Siberian Arctic. The isotope values, which reflect winter season temperatures, became progressively more enriched over the past 7,000 years, reaching unprecedented levels in the past five decades. This warming trend during the mid- to late Holocene is in opposition to the cooling seen in other proxy records. However, most of these existing proxy records are biased towards summer temperatures. We argue that the opposing trends are related to the seasonally different orbital forcing over this interval. Furthermore, our reconstructed trend as well as the recent maximum are consistent with the greenhouse gas forcing and climate model simulations, thus reconciling differing estimates of Arctic and northern high-latitude temperature evolution during the Holocene.

Meteorological observations and eddy covariance raw data from polygonal tundra in the Lena River Delta, Siberia

We present the first ecosystem-scale methane flux data from a northern Siberian tundra ecosystem covering the entire snow-free period from spring thaw until initial freeze-back. Eddy covariance measurements of methane emission were carried out from the beginning of June until the end of September in the southern central part of the Lena River Delta (72°22' N, 126°30' E). The study site is located in the zone of continuous permafrost and is characterized by Arctic continental climate with very low precipitation and a mean annual temperature of -14.7°C. We found relatively low fluxes of on average 18.7 mg/m**2/d, which we consider to be because of (1) extremely cold permafrost, (2) substrate limitation of the methanogenic archaea, and (3) a relatively high surface coverage of noninundated, moderately moist areas. Near-surface turbulence as measured by the eddy covariance system in 4 m above the ground surface was identified as the most important control on ecosystem-scale methane emission and explained about 60% of the variance in emissions, while soil temperature explained only 8%. In addition, atmospheric pressure was found to significantly improve an exponential model based on turbulence and soil temperature. Ebullition from waterlogged areas triggered by decreasing atmospheric pressure and near-surface turbulence is thought to be an important pathway that warrants more attention in future studies. The close coupling of methane fluxes and atmospheric parameters demonstrated here raises questions regarding the reliability of enclosure-based measurements, which inherently exclude these parameters.

(Table 1) Gas molecules, isotopic composition and delta Deuterium in DSDP Holes 95-603D and 95-613

Methane is the major hydrocarbon gas measured in Vacutainer samples from Holes 603D and 613 ( C1/sumCn > 0.999). In Hole 613 the concentration of this dry hydrocarbon gas is highest (7.4 x 10 **5 ppm max.) in the upper 60 to 120 m, then decreases erratically to low trace levels by 261 m sub-bottom (lower Pliocene). No gas accumulations were observed in older sediments. Methane from both holes is strongly depleted in both 13C (d13C, - 75 to -85 per mil) and deuterium (D/H, - 175 to -262 per mil), indicating the biogenic origin of the methane. The C and H isotopic compositions support methanogenesis via the CO2-reduction pathway; this is also corroborated by the dissolved-sulfate and alkalinity minima at these depths. The relationship between D/H of the methane and coexisting interstitial water from Site 613 further show the methanogenesis to be primarily by CO2 reduction.

Age model and palaeoclimate records over the past 22,000 years of sediment core GeoB10053-7

The Australian-Indonesian monsoon is an important component of the climate system in the tropical Indo-Pacific region. However, its past variability, relation with northern and southern high-latitude climate and connection to the other Asian monsoon systems are poorly understood. Here we present high-resolution records of monsoon-controlled austral winter upwelling during the past 22,000 years, based on planktic foraminiferal oxygen isotopes and faunal composition in a sedimentary archive collected offshore southern Java. We show that glacial-interglacial variations in the Australian-Indonesian winter monsoon were in phase with the Indian summer monsoon system, consistent with their modern linkage through cross-equatorial surface winds. Likewise, millennial-scale variability of upwelling shares similar sign and timing with upwelling variability in the Arabian Sea. On the basis of element composition and grain-size distribution as precipitation-sensitive proxies in the same archive, we infer that (austral) summer monsoon rainfall was highest during the Bølling-Allerød period and the past 2,500 years. Our results indicate drier conditions during Heinrich Stadial 1 due to a southward shift of summer rainfall and a relatively weak Hadley cell south of the Equator. We suggest that the Australian-Indonesian summer and winter monsoon variability were closely linked to summer insolation and abrupt climate changes in the northern hemisphere.

Iron Transformation Pathways and Redox Micro-Environments in Seafloor Sulfide-Mineral Deposits: Spatially Resolved Fe XAS and delta Fe-57/54 Observations

Hydrothermal sulfide chimneys located along the global system of oceanic spreading centers are habitats for microbial life during active venting. Hydrothermally extinct, or inactive, sulfide deposits also host microbial communities at globally distributed sites. The main goal of this study is to describe Fe transformation pathways, through precipitation and oxidation-reduction (redox) reactions, and examine transformation products for signatures of biological activity using Fe mineralogy and stable isotope approaches. The study includes active and inactive sulfides from the East Pacific Rise 9 degrees 50'N vent field. First, the mineralogy of Fe(III)-bearing precipitates is investigated using microprobe X-ray absorption spectroscopy (RXAS) and X-ray diffraction (mu XRD). Second, laser-ablation (LA) and micro-drilling (MD) are used to obtain spatially-resolved Fe stable isotope analysis by multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS). Eight Fe -bearing minerals representing three mineralogical classes are present in the samples: oxyhydroxides, secondary phyllosilicates, and sulfides. For Fe oxyhydroxides within chimney walls and layers of Si-rich material, enrichments in both heavy and light Fe isotopes relative to pyrite are observed, yielding a range of delta Fe-57 values up to 6 parts per thousand. Overall, several pathways for Fe transformation are observed. Pathway 1 is characterized by precipitation of primary sulfide minerals from Fe(II)aq-rich fluids in zones of mixing between vent fluids and seawater. Pathway 2 is also consistent with zones of mixing but involves precipitation of sulfide minerals from Fe(II)aq generated by Fe(III) reduction. Pathway 3 is direct oxidation of Fe(II) aq from hydrothermal fluids to form Fe(III) precipitates. Finally, Pathway 4 involves oxidative alteration of pre-existing sulfide minerals to form Fe(III). The Fe mineralogy and isotope data do not support or refute a unique biological role in sulfide alteration. The findings reveal a dynamic range of Fe transformation pathways consistent with a continuum of micro-environments having variable redox conditions. These micro-environments likely support redox cycling of Fe and S and are consistent with culture-dependent and -independent assessments of microbial physiology and genetic diversity of hydrothermal sulfide deposits.

Effect Of Atorvastatin On Wound Healing In Rats.

Skin-wound healing is a complex and dynamic biological process involving inflammation, proliferation, and remodeling. Recent studies have shown that statins are new therapeutical options because of their actions, such as anti-inflammatory and antioxidant activity, on vasodilation, endothelial dysfunction and neoangiogenesis, which are independent of their lipid-lowering action. Our aim was to investigate the effect of atorvastatin on tissue repair after acute injury in healthy animals. Rats were divided into four groups: placebo-treated (P), topical atorvastatin-treated (AT), oral atorvastatin-treated (AO), topical and oral atorvastatin-treated (ATO). Under anesthesia, rats were wounded with an 8-mm punch in the dorsal region. Lesions were photographed on Days 0, 1, 3, 7, 10, 12, and 14 post-injury and samples taken on Days 1, 3, 7, and 14 for protein-expression analysis of insulin receptor substrate (IRS)-1, phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), glycogen synthase kinase (GSK)-3, endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), extracellular signal-regulated kinase (ERK), interleukin (IL)-10, IL-1β, IL-6, and tumor necrosis factor (TNF)-α. Upon macroscopic examination, we observed significant reductions of lesion areas in groups AT, AO, and ATO compared to the P group. Additionally, AT and AO groups showed increased expression of IRS-1, PI3K, Akt, GSK-3, and IL-10 on Days 1 and 3 when compared with the P group. All atorvastatin-treated groups showed higher expression of IRS-1, PI3K, Akt, GSK-3, IL-10, eNOS, VEGF, and ERK on Day 7. On Days 1, 3, and 7, all atorvastatin-treated groups showed lower expression of IL-6 and TNF-α when compared with the P group. We conclude that atorvastatin accelerated tissue repair of acute lesions in rats and modulated expressions of proteins and cytokines associated with cell-growth pathways.