Mezen Bay—a key area for understanding Weichselian glaciations in northern Russia

Sediment successions in coastal cliffs around Mezen Bay, southeastern White Sea, record an unusually detailed history of former glaciations, interstadial marine and fluvial events from the Weichselian. A regional glaciation model for the Weichselian is based on new data from the Mezen Bay area and previously published data from adjacent areas. Following the Mikulinian (Eemian) interglacial a shelf‐centred glaciation in the Kara Sea is reflected in proglacial conditions at 100–90 ka. A local ice‐cap over the Timan ridge existed between 75 and 65 ka. Renewed glaciation in the Kara Sea spread southwestwards around 60 ka only, interrupted by a marine inundation, before it advanced to its maximum position at about 55–50 ka. After a prolonged ice‐free period, the Scandinavian ice‐sheet invaded the area from the west and terminated east of Mezen Bay about 17 ka. The previously published evidence of a large ice‐dammed lake in the central Arkhangelsk region, Lake Komi, finds no support in this study. Copyright © 2003 John Wiley & Sons, Ltd.     

Alpine medicinal plant trade and Himalayan mountain livelihood strategies

Commercial alpine medicinal plants are collected from the wild by local rural households throughout the Himalaya and sold in order to increase household incomes. Recent studies indicate that this annual trade amounts to thousands of tonnes of roots, rhizomes, tubers, leaves, etc., worth millions of US dollars. The main market is in India. Based on a national survey, including the most commonly traded species, and a village study this paper investigates the importance of the alpine medicinal plant trade at national and local levels in Nepal. The national survey included standardized open-ended interviews with 232 harvesters, 64 local traders, 66 central wholesalers, 47 regional wholesalers, and 16 production companies. The village survey is based on the daily records of household activities in 15 households in a one-year period. The annual Nepalese alpine and sub-alpine medicinal plant trade is conservatively estimated to vary from 480 to 2500 t with a total harvester value of US$0.8–3.3 million; the average harvester value is estimated at US$66.0 ± 99.0. The trade in 1997/98 amounted to 1600 t with a harvester value of US$2.3 million and an export value equivalent to 2.5% of total export from Nepal. Medicinal plant harvesting was found to constitute an integrated part of local livelihood strategies, contributing from 3 to 44% (average of 12%) of the annual household income. Importance at household level depended on land and animal holdings, and the availability of adult male labour. The validity and reliability of methods and analyses is evaluated, and issues of conservation and management of alpine medicinal plant species under the community forestry scheme are discussed.     

Site Response in Las Vegas Valley, Nevada from NTS Explosions and Earthquake Data

We report site response in Las Vegas Valley (LVV) from historical recordings of Nevada Test Site (NTS) nuclear explosions and earthquake recordings from permanent and temporary seismic stations. Our data set significantly improves the spatial coverage of LVV over previous studies, especially in the northern, deeper parts of the basin. Site response at stations in LVV was measured for frequencies in the range 0.2–5.0 Hz using Standard Spectral Ratios (SSR) and Horizontal-Vertical Spectral Ratios (HVR). For the SSR measurements we used a reference site (approximately NEHRP B ``rock' classification) located on Frenchman Mountain outside the basin. Site response at sedimentary sites is variable in LVV with average amplifications approaching a factor of 10 at some frequencies. We observed peaks in the site response curves at frequencies clustered near 0.6, 1.2 and 2.0 Hz, with some sites showing additional lower amplitude peaks at higher frequencies. The spatial pattern of site response is strongly correlated with the reported depth to basement for frequencies between 0.2 and 3.0 Hz, although the frequency of peak amplification does not show a similar correlation. For a few sites where we have geotechnical shear velocities, the amplification shows a correlation with the average upper 30-meter shear velocities, V₃₀. We performed two-dimensional finite difference simulations and reproduced the observed peak site amplifications at 0.6 and 1.2 Hz with a low velocity near-surface layer with shear velocities 600–750 m/s and a thickness of 100–200 m. These modeling results indicate that the amplitude and frequencies of site response peaks in LVV are strongly controlled by shallow velocity structure.     

Local ice caps in Finderup Land,North Greenland,survived the Holocene Thermal Maximum

Local glaciers and ice caps (GICs) comprise only ~5.4% of the total ice volume, but account for ~14–20% of the current ice loss in Greenland. The glacial history of GICs is not well constrained, however, and little is known about how they reacted to Holocene climate changes. Specifically, in North Greenland, there is limited knowledge about past GIC fluctuations and whether they survived the Holocene Thermal Maximum (HTM, ~8 to 5 ka). In this study, we use proglacial lake records to constrain the ice‐marginal fluctuations of three local ice caps in North Greenland including Flade Isblink, the largest ice cap in Greenland. Additionally, we have radiocarbon dated reworked marine molluscs in Little Ice Age (LIA) moraines adjacent to the Flade Isblink, which reveal when the ice cap was smaller than present. We found that outlet glaciers from Flade Isblink retreated inland of their present extent from ~9.4 to 0.2 cal. ka BP. The proglacial lake records, however, demonstrate that the lakes continued to receive glacial meltwater throughout the entire Holocene. This implies that GICs in Finderup Land survived the HTM. Our results are consistent with other observations from North Greenland but differ from locations in southern Greenland where all records show that the local ice caps at low and intermediate elevations disappeared completely during the HTM. We explain the north–south gradient in glacier response as a result of sensitivity to increased temperature and precipitation. While the increased temperatures during the HTM led to a complete melting of GICs in southern Greenland, GICs remained in North Greenland probably because the melting was counterbalanced by increased precipitation due to a reduction in Arctic sea‐ice extent and/or increased poleward moisture transport.     

电离层水平不均匀性对无线电掩星资料反演的影响

电离层水平不均匀结构是引起掩星资料反演的主要误差源.本文模拟不均匀结构对无线电掩星资料反演的影响.首先利用3-D全球射线追踪技术进行了模拟.结果指出:电离层电子密度20%的变化可能引起GPS的时延增加约12m.其次,将90%的掩星时延对应的路径长度,定义为电离层掩星测量的水平分辨率,其值为1200-2000 km.最后,计算了不同纬度电离层当地正午、子夜和日出时的电离层水平不对称指数.它表明:低纬夏季日出时,不对称指数达-78%,反演结果可能有较大误差.     

Governing resilience building in Thailand's tourism-dependent coastal communities: Conceptualising stakeholder agency in social-ecological systems

In current scientific efforts to harness complementarity between resilience and vulnerability theory, one response is an ‘epistemological shift’ towards an evolutionary, learning based conception of the ‘systems-actor’ relation in social-ecological systems. In this paper, we contribute to this movement regarding the conception of stakeholder agency within social-ecological systems. We examine primary evidence from the governance of post-disaster recovery and disaster risk reduction efforts in Thailand's coastal tourism-dependent communities following the 2004 Indian Ocean Tsunami. Through an emerging storyline from stakeholders, we construct a new framework for conceptualising stakeholder agency in social-ecological systems, which positions the notion of resilience within a conception of governance as a negotiated normative process. We conclude that if resilience theory is proposed as the preferred approach by which disaster risk reduction is framed and implemented, it needs to acknowledge much more explicitly the role of stakeholder agency and the processes through which legitimate visions of resilience are generated.     

Mobilization of arsenic and iron from Red River floodplain sediments, Vietnam

Sediments from the Red River and from an adjacent floodplain aquifer were investigated with respect to the speciation of Fe and As in the solid phase, to trace the diagenetic changes in the river sediment upon burial into young aquifers, and the related mechanisms of arsenic release to the groundwater. Goethite with subordinate amounts of hematite were, using Mössbauer spectroscopy, identified as the iron oxide minerals present in both types of sediment. The release kinetics of Fe, As, Mn and PO₄ from the sediment were investigated in leaching experiments with HCl and 10 mM ascorbic acid, both at pH 3. From the river sediments, most of the Fe and As was mobilized by reductive dissolution with ascorbic acid while HCl released very little Fe and As. This suggests As to be associated with an Fe-oxide phase. For oxidized aquifer sediment most Fe was mobilized by ascorbic acid but here not much As was released. However, the reduced aquifer sediments contained a large pool of Fe(II) and As that is readily leached by HCl, probably derived from an unidentified authigenic Fe(II)-containing mineral which incorporates As as well. Extraction with ascorbic acid indicates that the river sediments contain both As(V) and As(III), while the reduced aquifer sediment almost exclusively releases As(III). The difference in the amount of Fe(II) leached from river and oxidized aquifer sediments by ascorbic acid and HCl, was attributed to reductive dissolution of Fe(III). The reactivity of this pool of Fe(III) was quantified by a rate law and compared to that of synthetic iron oxides. In the river mud, Fe(III) had a reactivity close to that of ferrihydrite, while the river sand and oxidized aquifer sediment exhibited a reactivity ranging from lepidocrocite or poorly crystalline goethite to hematite. Mineralogy by itself appears to be a poor predictor of the iron oxide reactivity in natural samples using the reactivity of synthetic Fe-oxides as a reference. Sediments were incubated, both unamended and with acetate added, and monitored for up to 2 months. The river mud showed the fastest release of both Fe and As, while the effect of acetate addition was minor. This suggests that the presence of reactive organic carbon is not rate limiting. In the case of the river and aquifer sediments, the release of Fe and As was always stimulated by acetate addition and here reactive organic carbon was clearly the rate limiting factor. The reduced aquifer sediment apparently can sustain slower but prolonged microbially-driven release of As. The highly reactive pools of Fe(III) and As in the river mud could be due to reoxidation of As and Fe contained in the reducing groundwater from the floodplain aquifers that are discharging into the river. Deposition of the suspended mud on the floodplain during high river stages is proposed to be a major flux of As onto the floodplain and into the underlying aquifers.     

Simplification and Validation of a Spectral-Tensor Model for Turbulence Including Atmospheric Stability

A spectral-tensor model of non-neutral, atmospheric-boundary-layer turbulence is evaluated using Eulerian statistics from single-point measurements of the wind speed and temperature at heights up to 100 m, assuming constant vertical gradients of mean wind speed and temperature. The model has been previously described in terms of the dissipation rate \(\epsilon \), the length scale of energy-containing eddies \(\mathcal {L}\), a turbulence anisotropy parameter \(\varGamma \), the Richardson number Ri, and the normalized rate of destruction of temperature variance \(\eta _\theta \equiv \epsilon _\theta /\epsilon \). Here, the latter two parameters are collapsed into a single atmospheric stability parameter z / L using Monin–Obukhov similarity theory, where z is the height above the Earth’s surface, and L is the Obukhov length corresponding to \(\{Ri,\eta _\theta \}\). Model outputs of the one-dimensional velocity spectra, as well as cospectra of the streamwise and/or vertical velocity components, and/or temperature, and cross-spectra for the spatial separation of all three velocity components and temperature, are compared with measurements. As a function of the four model parameters, spectra and cospectra are reproduced quite well, but horizontal temperature fluxes are slightly underestimated in stable conditions. In moderately unstable stratification, our model reproduces spectra only up to a scale \(\sim \) 1 km. The model also overestimates coherences for vertical separations, but is less severe in unstable than in stable cases.     

Swedish coastal fisheries—From conflict mitigation to participatory management

Several research projects have studied Swedish coastal fishery to investigate the conflict between seals and fishery. In recent years, a strategy of participation by means of co-management has been unfolding. Realising that maintaining the coastal fishery requires societal support and knowledge integration, attempts have been made to introduce the principle of participatory management into the centralised Swedish fisheries management system. However, this co-management approach, presently implemented in six pilot projects, will take a long time to develop through a sustained process of experimentation and improvement.