High-resolution climate simulation of the last glacial maximum

The climate of the last glacial maximum (LGM) is simulated with a high-resolution atmospheric general circulation model, the NCAR CCM3 at spectral truncation of T170, corresponding to a grid cell size of roughly 75 km. The purpose of the study is to assess whether there are significant benefits from the higher resolution simulation compared to the lower resolution simulation associated with the role of topography. The LGM simulations were forced with modified CLIMAP sea ice distribution and sea surface temperatures (SST) reduced by 1°C, ice sheet topography, reduced CO₂, and 21,000 BP orbital parameters. The high-resolution model captures modern climate reasonably well, in particular the distribution of heavy precipitation in the tropical Pacific. For the ice age case, surface temperature simulated by the high-resolution model agrees better with those of proxy estimates than does the low-resolution model. Despite the fact that tropical SSTs were only 2.1°C less than the control run, there are many lowland tropical land areas 4–6°C colder than present. Comparison of T170 model results with the best constrained proxy temperature estimates (noble gas concentrations in groundwater) now yield no significant differences between model and observations. There are also significant upland temperature changes in the best resolved tropical mountain belt (the Andes). We provisionally attribute this result in part as resulting from decreased lateral mixing between ocean and land in a model with more model grid cells. A longstanding model-data discrepancy therefore appears to be resolved without invoking any unusual model physics. The response of the Asian summer monsoon can also be more clearly linked to local geography in the high-resolution model than in the low-resolution model; this distinction should enable more confident validation of climate proxy data with the high-resolution model. Elsewhere, an inferred salinity increase in the subtropical North Atlantic may have significant implications for ocean circulation changes during the LGM. A large part of the Amazon and Congo Basins are simulated to be substantially drier in the ice age—consistent with many (but not all) paleo data. These results suggest that there are considerable benefits derived from high-resolution model regarding regional climate responses, and that observationalists can now compare their results with models that resolve geography at a resolution comparable to that which the proxy data represent.     

Lithostratigraphy, Sedimentology, and Provenance of the Balfour Formation (Beaufort Group) in the Fort Beaufort–Alice Area, Eastern Cape Province, South Africa

Abstract: The Balfour Formation has a pronounced lithological variation that is characterized by alternating sandstone- and mudstone-dominated members. The sandstone-dominated Oudeberg and Barberskrans Members are composed of lithofacies that range from intraformational conglomerates to fine-grained sediments, whereas the mudstone-dominated members (Daggaboersnek, Elandsberg, and Palingkloof) are dominated by the facies Fm and Fl. Petrography, geochemistry, and a paleocurrent analysis indicated that the source rock of the Balfour Formation was to south east and the rocks had a transitional/dissected magmatic arc signature. The sandstones-rich members were deposited by seasonal and ephemeral high-energy, low-sinuous streams, and the fine-grained-rich members were formed by ephemeral meandering streams. The paleoclimates have been equated to present temperate climates; they were semiarid becoming arid towards the top of the Balfour Formation. This has been determined by reconstructing the paleolatitude of the Karoo Basin, geochemistry, paleontology, sedimentary structures, and other rock properties, like color.     

Hydrogen photoproduction ofA. Variabilis incorporated in a photobioreactor

H₂ photoproduction and nitrogenase activities in two strains ofAnabaena variabilis marked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than the normal incubation temperature of 30°C) were studied. Cultures of both strains collected from any interval of logarithmic growth phase exhibited high H₂ photoproduction and nitrogenase activities when exposed to limited time heat shock during the assay process. In contrast, the algal H₂ photoproduction rate of both strains fluctuated with long term thermal stress caused by increasing the growth temperature from 30°C to 36°C.

The changes of nitrogenase (the key H₂ photobiosynthetic enzyme) activities in the mutant PK84 showed variation tendency similar to that of H₂ photoproduction during exposure to thermal stress, indicating that fluctuation of H₂ photoproduction in the mutant was mainly due to the variation of nitrogenase activities. A temporary maximal H₂ photoproduction in the mutant PK84 (wild type ATCC29413) was observed when cells grew at 36°C for 14 (6) days. However, the responses of nitrogenase activities in the wild type to thermal stress were not completely similar to those in the mutant in spite of similar variations of H₂ photoproduction in both strains. The data obtained in these studies suggested that the activities of other enzymes (in the wild strain) involved in H₂ photoproduction were affected by thermal stress since H₂ photoproduction maximized or dropped to 0 without variation tendency similar to that of nitrogenase activities.

Furthermore, an enhancement of H₂ photoproduction speed of the mutant strain cultured in a 4.4 L laboratory photobioreactor was also observed when it was subjected to short time continuous charge of argon, and temperature rise.

All these results indicated that high temperature plays an important role in the photo-autotrophic H₂ photoproduction, and that long term thermal stress is unfavourable for net H₂ photoproduction in both strains ofA. variabilis though short-time heat shock is conducive to H₂ photoproduction.

     

CSCO_3 CYCLES IN SALAWUSU RIVER BASINSINCE 150KA B.P.

About 70years ago，Frenc卜卜alaeohdoglst回LL sc卜dars al卜ome and a卜road卜ave successively con－HARD de Chardin P．et al．Initiated the Quaternary ducted large amount ofwork on the Later Quaternarygeologlcal research In the ＞alawusu River Basin of strata（TEILHARD，1924； YUAN，1978； LI，1987；desert region of Northern China and established th，ZHENG，1989； SUN et al，1996； LI et al，1993），Salawusu Formation门EILHARD，1924）．Sine，then，palaeobiology…     

Using unmanned underwater vehicles as research platforms in coastal ocean studies

The advantages of using unmanned underwater vehicles in coastal ocean studies are emphasized. Two types of representative vehicles, remotely operated vehicle (ROV) and autonomous underwater vehicle (AUV) from University of South Florida, are discussed. Two individual modular sensor packages designed and tested for these platforms and field measurement results are also presented. The bottom classification and albedo package, BCAP, provides fast and accurate estimates of bottom albedos, along with other parameters such as in-water remote sensing reflectance. The real-time ocean bottom optical topographer, ROBOT, reveals high-resolution 3-dimentional bottom topography for target identification. Field data and results from recent Coastal Benthic Optical Properties field campaign, 1999 and 2000, are presented. Advantages and limitations of these vehicles and applications of modular sensor packages are compared and discussed.     

Integrated and Participatory Research Approaches towards Sustainable Livelihoods and Ecosystems in Mountainous Regions

Mountainous regions cover about 27 per cent of the world’s land surface and are home to some 22 per cent of the global population (UNEP 2002). A much greater number of people depend on mountain environments for a wide range of services, including clean water, energy, timber, biodiversity, recreation, and protection from environmental hazards, such as landslides and floods. At the same time, mountain areas are extremely vulnerable ecosystems and under continuous threat of environmental degrad…     

Reach‐scale contributions of road‐surface sediment to the Honna River,Haida Gwaii,BC

Gravel road surfaces can be a major source of fine sediment to streams, yet their contribution to channel reach sediment balances remains poorly documented. To quantify the input of road surface material and to compare this input with natural sediment sources at the reach scale, suspended sediment dynamics was examined and a 16‐month sediment balance was developed for a ~35 channel‐width (approx. 425 m) reach of the Honna River, a medium‐size, road‐affected stream located in coastal British Columbia. Of the 105 ± 33 t of suspended material passing through the reach, 18 ± 6% was attributed to the road surface. The high availability of sediment on the road surface appears to limit hysteresis in road run‐off. During rainstorms that increase streamflow, road surface material composed 0.5–15% of sediment inputs during relatively dry conditions from April to the end of September and 5–70% through wetter conditions from October to the end of March, but our data do not show evidence of major sediment accumulation on the riverbed in the reach. A comparison of modelled sediment production on the road surface with observed yields from drainage channels suggests that (1) during low intensity rainfall, ditches and drainage channels may trap sediment from road run‐off, which is subsequently released during events of greater intensity, and/or (2) production models do not effectively describe processes, such as deposition or erosion of sediment in ditches, which control sediment transport and delivery. Our findings further emphasize the risk of unpaved roads in polluting river systems and highlight the continued need for careful road design and location away from sensitive aquatic environments. Copyright © 2016 John Wiley & Sons, Ltd.     

Coalification in Carboniferous sediments from the Lötschberg base tunnel

Vitrinite reflectance (Rr), proximate analysis and carbon isotope composition (δ¹³C) have been used to characterise coal samples from two zones of Late Carboniferous sediments (Gastern and Ferden) in the Aar massif where they are penetrated by the Lötschberg base tunnel (constructed between 1999 and 2005). Samples are characterised by variable ash yields (21.7–93.9%; dry basis); those with ash yields of less than ~50% and with volatile matter content (V;dry ash-free basis) within the limits 2 < V% ≤ 8 are anthracite. Values of Rr range from 3.89% to 5.17% and indicate coalification to the rank of anthracite and meta-anthracite in both Gastern and Ferden Carboniferous zones. Samples of anthracite and shale from the Gastern Carboniferous exhibit a relatively small range in δ¹³C values (–24.52‰ to –23.38‰; mean: –23.86‰) and are lighter than anthracite samples from the Ferden Carboniferous (mean: –22.20‰). The degree of coalification in the Gastern and Ferden Carboniferous zones primarily depends on the maximum rock temperature (T) attained as a result of burial heating. Vitrinite reflectance based estimates of T range from ~290° –360 °C. For a proposed palaeogeothemal gradient of 25 ° C/km at the time of maximum coalification the required overburden is attributable to relatively thin autochtonous Mesozoic/Cenozoic sedimentary cover of the Aar massif and Gastern granite and deep tectonic burial beneath advancing Helvetic, Ultrahelvetic and Prealpine (Penninic) nappes in Early Oligocene to Miocene.