Without power? Landslide inventories in the face of climate change

Projected scenarios of climate change involve general predictions about the likely changes to the magnitude and frequency of landslides, particularly as a consequence of altered precipitation and temperature regimes. Whether such landslide response to contemporary or past climate change may be captured in differing scaling statistics of landslide size distributions and the erosion rates derived thereof remains debated. We test this notion with simple Monte Carlo and bootstrap simulations of statistical models commonly used to characterize empirical landslide size distributions. Our results show that significant changes to total volumes contained in such inventories may be masked by statistically indistinguishable scaling parameters, critically depending on, among others, the size of the largest of landslides recorded. Conversely, comparable model parameter values may obscure significant, i.e. more than twofold, changes to landslide occurrence, and thus inferred rates of hillslope denudation and sediment delivery to drainage networks. A time series of some of Earth's largest mass movements reveals clustering near and partly before the last glacial‐interglacial transition and a distinct step‐over from white noise to temporal clustering around this period. However, elucidating whether this is a distinct signal of first‐order climate‐change impact on slope stability or simply coincides with a transition from short‐term statistical noise to long‐term steady‐state conditions remains an important research challenge. Copyright © 2011 John Wiley & Sons, Ltd.     

High potential activity of extracellular alkaline phosphatase in deep waters of the central Pacific

We found high potential activities of alkaline phosphatase associated with particles (0.2 μm or greater size fraction) in deep waters (1000–4000 m) of the central Pacific Ocean. The potential enzyme activity at depth (0.03 – 0.3 nM h⁻¹) was up to 50% of that at the surface (0–125 m). In contrast, activities of α- and β-d-glucosidase in the deep layer were low (generally less than 1 % of those in the upper layer), yielding up to two orders of magnitude difference in the ratio of alkaline phosphatase and α- and β-d-glucosidase activities with depth. It is unlikely that the phosphatase is actively produced by microorganisms inhabiting the deep-sea environment, where labile organic carbon supply is limited and phosphate concentration is high (2.4 – 3.0 AM). Instead, deep-water phosphatase is probably supplied by rapidly sinking particles and their subsequent fragmentation and dissolution. Different distributions of phosphatase and glucosidase indicate that sinking particles of phytoplankton origin are an important source of alkaline phosphatase enzymes in the deep sea.     

Characterizing the flush of stream chemical runoff from forested watersheds

A flush can be defined as stream chemical exhibiting higher concentrations during the prophase of a storm event at an event scale, or exhibiting progressively lower concentrations during several successive storms at a seasonal scale. Investigating the flush characteristics of chemical runoff from forested watersheds is important and helpful to understand the chemical dynamics as well as to design a sampling schedule strategy during storm events. Here, three parameters describing the flush characteristic are quantified and the flush characteristics of chemicals from four Japanese forested watersheds (Mie, Kochi, Nagano and Tokyo) were investigated at both event and seasonal levels. We found that the characteristics of the flush were complicated, and depended on the constituents of the hydrochemistry, climate and runoff quality. Generally, the flush occurs more readily for particulate components than for those in solution; the flush on nitrate‐nitrogen is weaker in regions of nitrogen saturation, such as Nagano and Tokyo, than in Mie and Kochi. Rainfall feature was the main factor controlling the flush of particulate components. However, the source available in a watershed plays a main role on the flushes of dissolve chemicals. Copyright © 2010 John Wiley & Sons, Ltd.     

Evaluation of spatial correlation between nutrient exchange rates and benthic biota in a reef-flat ecosystem by GIS-assisted flow-tracking

A Geographic Information System (GIS)-aided flow-tracking technique was adopted to investigate nutrient exchange rates between specific benthic communities and overlying seawater in a fringing reef of Ishigaki Island, subtropical Northwestern Pacific. Net exchange rates of NO₃ ⁻, NO₂ ⁻, NH₄ ⁺, PO₄ ³⁻, Total-N and Total-P were estimated from concentration changes along the drogue trajectories, each of which was tracked by the Global Positioning System and plotted on a benthic map to determine the types of benthic habitat over which the drogue had passed. The observed nutrient exchange rates were compared between 5 typical benthic zones (branched-coral (B) and Heliopora communities (H), seaweed-reefrock zone (W), bare sand area (S), and seagrass meadow (G)). The dependence of nutrient exchange rates on nutrient concentrations, physical conditions and benthic characteristics was analyzed by multiple regression analysis with the aid of GIS. The spatial correlation between nutrient exchange rates and benthic characteristics was confirmed, especially for NO₃ ⁻ and PO₄ ³⁻, which were usually absorbed in hydrographically upstream zones B and W and regenerated in downstream zones H and G. NO₃ ⁻ uptake in zones B and W was concentration-dependent, and the uptake rate coefficient was estimated to be 0.58 and 0.67 m h⁻¹, respectively. Both nutrient uptake in zone W and regeneration in zone H were enhanced in summer. The net regeneration ratio of NO₃ ⁻/PO₄ ³⁻ in zone H in summer ranged 5.2 to 34 (mean, 17.4), which was somewhat higher than previously measured NO₃ ⁻/PO₄ ³⁻ for sediment pore waters around this zone (1.1–8.5). Nutrient exchanges in zone S were relatively small, indicating semi-closed nutrient cycling at the sediment-water interface of this zone. NH₄ ⁺ efflux from sediments was suggested in zone G. The data suggest that the spatial pattern of nutrient dynamics over the reef flat community was constrained by zonation of benthic biota, and that abiotic factors such as nutrient concentrations and flow rates, influenced nutrient exchange rates only in absorption-dominated communities such as zones B and W.     

Discovery Of Mg-Rich Pyroxenes In Comet C/1995 O1 (Hale-Bopp): Pristine Grains Revealed At Perihelion

The NASA Ames HIFOGS spectrometer observed comet C/1995 O1 (Hale-Bopp) at epochs including 96 Oct 7–14 UT (2.8 AU), 97 Feb 14–15 UT (1.2 AU), 97 Apr 11 UT (0.93 AU), and 97 Jun 22, 25 UT (1.7 AU). The HIFOGS 7.5–13.5 μm spectrophotometry (R = 360 - 180) of the silicate feature at 2.8 AU is identical in shape to the ISO SWS spectra of comet Hale-Bopp (Crovisier et al., 1997); the strong 11.2 μm peak in the structured silicate feature is identified as olivine. Upon close passage to the sun, the HIFOGS spectra at 1.2 AU and 0.93 AU reveals strong peaks at 9.3 μm and 10.0 μm. The post-perihelion 10 μm silicate feature at 1.7 AU is weaker but has nearly the same shape as the pre-perihelion spectra at 1.2 AU, reverting to its pre-perihelion shape: there is no change in the dust chemistry by close passage to the sun. The appearance of the strong peaks at 9.3 μm and 10.0 μm at r_h ≲ 1.7 AU is attributed to the rise in the contribution of pryoxenes (clino-pyroxene and orthopyroxene crystals) to the shape of the feature, and leads to the hypothesis that the pyroxenes are significantly cooler than the olivines. The pyroxenes are radiating on the Wien side of the blackbody at 2.8 AU and transition to the Rayleigh-Jeans tail of the blackbody upon closer approach to the Sun. Composite fits to the observed 10 μm silicate features using IDPs and laboratory minerals shows that a good empirical fit to the spectra is obtained when the pryoxenes are about 150 K cooler than the olivines. The pyroxenes, because they are cooler and contribute signficantly at perihelion, are more abundant than the olivines. The perihelion temperature of the pyroxenes implies that the pyroxenes are more Mg-rich than the other minerals including the olivines, amorphous olivines, and amorphous pyroxenes. The PUMA-1 flyby measurements of comet P/Halley also indicated an overabundance of Mg-rich pryoxenes compared to olivines. Comet Hale-Bopp's pyroxenes are similar to pyroxere IDPs from the ’Spray‘ class, known for their D-richness and their unaltered morphologies: Hale-Bopp's Mg-rich pyroxenes may be pristine relic ISM grains. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of regional net radiation and soil heat flux over a heterogeneous landscape of the Tibetan Plateau

This paper explores the potential for documenting regional fields of surface energy fluxes over the Tibetan plateau using published algorithms and previously calibrated empirical formulae with data from NOAA‐14 AVHRR and atmospheric data collected during the GAME‐Tibet field experiment. Comparison with observations at three field sites suggests errors in the resulting estimates are less than 10% in the clear sky conditions necessary for application of this approach. Because of the need for clear skies, it was only possible to calculate the desired regional fields for one satellite scene during the 5 month study period. Maps of surface energy fluxes, and frequency analyses of these maps, are presented for this scene. The need for an alternative, more consistently applicable, satellite‐based method to map surface energy fields is highlighted. Copyright © 2002 John Wiley & Sons, Ltd.     

Sedimentary Features of Tsunami Deposits in Carbonate-Dominated Beach Environments: A Case Study from the 25 October 2010 Mentawai Tsunami

This study provides a case history of tsunami deposition in a carbonate-dominated environmental setting. We present the results of a sedimentological investigation conducted on deposits formed by the 25 October 2010 Mentawai Island Tsunami and report on deposits analyzed at three sites on North Pagai Island: Sabeu Gunggung, Macaroni Resort, and Tumalei. The deposits are mainly composed of medium to coarse sand-sized fragments of corals, shells and foraminifera, with thickness ranging from 3 to 26 cm. The deposits consist of two to five layers, with fining-upward trends dominating. Local topography noticeably affects the thickness, number of layers, and distribution of tsunami deposits. The foraminiferal assemblage and diversity vary at each sample point, along transect and between different transects. Based on the foraminiferal content, most of the deposit material likely came from shallower depths. In addition, density distribution of the tsunami deposit material exhibits some degree of variability in terms of the range of densities in each sample and the trend of the overall density along each transect. In contrast to heavy mineral-dominated deposits, the density of carbonate grains as a function of size may be an important consideration when carbonate-dominated deposits are used to interpret hydraulic conditions that created a particular tsunami deposit. Since there are relatively few studies of tsunami deposits in carbonate-dominated environmental settings such as the Mentawai Islands, our study provides a useful case history of tsunami deposition in such an environmental setting.     

Field measurements of absolute gravity in East Antarctica

Abstract This paper reports the results of field-based absolute gravity measurements aimed at detecting gravity change and crustal displacement caused by glacial isostatic adjustment. The project was initiated within the framework of the 53rd Japanese Antarctic Research Expedition （JARE53）. Absolute gravity measurements, together with GPS measurements, were planned at several outcrops along the Prince Olav Coast and S6ya Coast of East Antarctica, including at Syowa Station. Since the icebreaker Shirase （AGB 5003） was unable to moor alongside Syowa Station, operations were somewhat restricted during JARE53. However, despite this setback, we were able to complete measurements at two sites： Syowa Station and Langhovde. The absolute gravity value at the Syowa Station IAGBN （A） site, observed using an FG-5 absolute gravimeter （serial number 210; FG-5 #210）, was 982 524 322.7＋0.1 ktGal, and the gravity change rate at the beginning of 2012 was -0.26 gGal.a-1. An absolute gravity value of 982 535 584.2~0.7 ktGal was obtained using a portable A-10 absolute gravimeter （serial number 017; A-10 #017） at the newly located site AGS01 in Langhovde.     

The countermeasures against coastal hazards in Japan

The total length of Japanese coastline is about 34,500 km. Most of the coastal lowlands are now so intensively used that a large proportion of the Japanese coast has been artificially modified. Therefore, coastal countermeasures against several kinds of natural and man-induced hazards are the serious problems for Japanese. When we go down to the beaches, there are many kinds of armor blocks, breakwaters and dykes for the shore protection. Among the Japanese coastline, 15,900 km needs some protection of which 9,400 km was protected with some kinds of artificial structures in 1992. It is probable that no nation has used armor blocks so extensively as Japan.