New Zealand coastal planning: an issue-based approach     

Johanna Rosier  Wayne Hastie 《Ocean & Coastal Management》1996,33(1-3)

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Vulnerability and adaptation in a dryland community of the Elqui Valley, Chile   总被引：1，自引：0，他引：1  

Gwendolynne Young  Humberto Zavala  Johanna Wandel  Barry Smit  Sonia Salas  Elizabeth Jimenez  Melitta Fiebig  Roxana Espinoza  Harry Diaz  Jorge Cepeda 《Climatic change》2010,98(1-2):245-276

Livelihoods in drylands are already challenged by the demands of climate variability, and climate change is expected to have further implications for water resource availability in these regions. This paper characterizes the vulnerability of an irrigation-dependent agricultural community located in the Elqui River Basin of Northern Chile to water and climate-related conditions in light of climate change. The paper documents the exposures and sensitivities faced by the community in light of current water shortages, and identifies their ability to manage these exposures under a changing climate. The IPCC identifies potentially increased aridity in this region with climate change; furthermore, the Elqui River is fed by snowmelt and glaciers, and its flows will be affected by a warming climate. Community vulnerability occurs within a broader physical, economic, political and social context, and vulnerability in the community varies amongst occupations, resource uses and accessibility to water resources, making some more susceptible to changing conditions in the future. This case study highlights the need for adaptation to current land and water management practices to maintain livelihoods in the face of changes many people are not expecting.  相似文献   

Direct and indirect luminescence dating of tephra: A review     

Janina Johanna Bösken  Christoph Schmidt 《第四纪科学杂志》2020,35(1-2):39-53

In Quaternary studies, tephras are widely used as marker horizons to correlate geological deposits. Therefore, accurate and precise dating is crucial. Among radiometric dating techniques, luminescence dating has the potential to date tephra directly using glass shards, volcanic minerals that formed during the eruption or mineral fragments that originate from the shattered country rock. Moreover, sediments that frame the tephra can be dated to attain an indirect age bracket. A review of numerous luminescence dating studies highlights the method's potential and challenges. While reliable direct dating of volcanic quartz and feldspar as a component in tephra is still methodically difficult mainly due to thermal and athermal signal instability, red thermoluminescence of volcanic quartz and the far-red emission of volcanic feldspar have been used successfully. Furthermore, the dating of xenolithic quartz within tephra shows great potential. Numerous studies date tephra successfully indirectly. Dating surrounding sediments is generally straightforward as long as samples are not taken too close to the tephra horizons. Here, issues arise from the occurrence of glass shards within the sediments or unreliable determination of dose rates. This includes relocation of radioelements, mixing of tephra into the sediment and disregarding different dose rates of adjacent material.  相似文献   

Determination of Boron Concentration in Geochemical Reference Materials Extracted by Pyrohydrolysis and Measured by ICP‐MS          下载免费PDF全文

Agnès Michel  Johanna Noireaux  Mickaël Tharaud 《Geostandards and Geoanalytical Research》2015,39(4):489-495

This article presents new boron concentrations for nine geochemical reference materials (GS‐N, FK‐N, GL‐O, BX‐N, DT‐N, AN‐G, GH, Mica‐Fe, Mica‐Mg). After extraction by a modified pyrohydrolysis technique, boron concentrations were measured by ICP‐MS. The blank levels for the whole procedure were 0.091 ± 0.020 ng ml^?1 or 14 ± 5 ng of boron in total. The method was first validated by measuring nine reference materials with known boron concentrations. The determined boron concentrations are all within the range of recommended or published values, which means that the yields were 100%, and show precisions below 10% for samples containing over 2 μg g^?1 of boron.  相似文献   

The Effects of Plateau Pika (Ochotona curzoniae) Presence and Population Control on the Structure of an Alpine Grassland Bird Community     

Joseph P. LAMBERT  Johanna V. HARTMANN  SHI Kun  Philip RIORDAN 《资源与生态学报(英文版)》2023,14(1):46-56

China’s Qinghai-Tibetan Plateau (QTP) is an important area for bird conservation, with many endemic and Threatened species. Colonial burrowing mammals play an important role in structuring bird communities in arid grasslands around the world. On the QTP, the plateau pika Ocho tona curzoniae builds colonies which provide a dense source of resources for many bird species. However, pikas are regarded as a pest by local pastoralists, and they are the target of a population reduction campaign which could have a significant impact on the bird communities. We surveyed bird communities at Gansu Yanchiwan National Nature Reserve to investigate the differences in community structure between sites with pika colonies (on colony) and sites without them (off colony), and between pika colonies which had been poisoned and those which had not. Using non-metric multidimensional scaling (NMDS) combined with permutational multivariate analysis of variance (PERMANOVA) and Wilcoxon rank-sum tests, we found that there was no significant difference in bird community composition or abundance between the poisoned and untreated colonies. However, there was a very large and statistically significant difference in bird community structures between on- and off-colony sites. Only horned lark Eremophila alpestris was consistently observed at sites without pika colonies, while ten bird species were observed on colonies. Six species were significantly more abundant on colony than off. While we could not claim that the poisoning campaign at Yanchiwan is altering bird communities, the presence of pika colonies seems to be an indispensable resource for the resident birds.  相似文献   

Geogas transport in fractured hard rock – Correlations with mining seismicity at 3.54 km depth, TauTona gold mine, South Africa     

Johanna Lippmann-Pipke  Jörg Erzinger  Martin Zimmer  Christian Kujawa  Margaret Boettcher  Esta Van Heerden  Armand Bester  Hannes Moller  Nicole A. Stroncik  Zeev Reches 《Applied Geochemistry》2011,26(12):2134-2146

An on-site gas monitoring study has been conducted in the framework of an earthquake laboratory (The International NELSAM–DAFGAS projects) at the TauTona gold mine, South Africa. Five boreholes up to 60 m long were drilled at 3.54 km depth into the highly fractured Pretorius Fault Zone and instruments for chemical and seismic monitoring installed therein. Over the span of 4 years sensitive gas monitoring devices were continuously improved to enable the direct observation of geogas concentration variations in the DAFGAS borehole. The major gas concentrations are constant and air-like with about 78% N₂, 21% O₂, 1% Ar. The geogas components CO₂, CH₄, He and H₂ show the most interesting trends and variations on the minute-by-minute basis and significantly correlate with seismic data, while the ²²²Rn activity remains constant. Time series and cross correlation analysis allow the identification of different gas components (geogas and tunnel air) and the identification of two processes influencing the borehole gas composition: (1) pumping-induced tunnel air breakthrough through networks of initially water-saturated fault fractures; and (2) seismicity induced permeability enhancement of fault fractures to above ∼5 × 10^-10 m². The current set-up of the gas monitoring system is sensitive enough to quantify the resulting geogas transport during periods of intense blasting activities (including recorded blasts with seismic moment ?1 × 10⁹ Nm, located within 1000 m of the cubby) and, it is suggested, also during induced earthquakes, a final goal of the project.  相似文献   

The occurrence and depth penetration of macroalgae along environmental gradients in the northern Baltic Sea     

Henna Rinne  Sonja Salovius-Laurén Johanna Mattila 《Estuarine, Coastal and Shelf Science》2011,94(2):182-191

Eutrophication is known to affect the community structure of macroalgae by e.g. decreasing the depth penetration of species and by shifting dominance from perennial to annual species. However, there is substantial lack of knowledge in the Baltic Sea regarding the distribution of many of the macroalgal species, how natural environmental factors affect their occurrence and how they respond to eutrophication. As macroalgae are used as indicators of the quality of the sea areas in the EU legislation (Water Framework Directive, Marine Strategy Framework Directive), this kind of knowledge is essential. The aim of this study was to determine which variables were related to variation in species occurrence and their lower limit of occurrence in the Finnish marine area. The study was carried out on data from five study areas along the Finnish coastline and included about 30 taxa. Our results showed that both the macroalgal communities and the occurrence (presence/absence) of most of the species differed between the study areas and that the differences were mainly related to salinity and exposure, although also eutrophication related factors played a role. Of the perennial species, eutrophied conditions seemed to favour only the occurrence of Sphacelaria arctica and Polysiphonia fucoides. Secchi depth was important in determining the lower limit of occurrence of brown and red algal species. However, Secchi depth was rarely the only factor causing variation in the lower limit of occurrence as also exposure, salinity and slope of the shore affected it. We conclude that in the northern Baltic Sea, the taxonomic composition of the macroalgal communities is not a very useful indicator of eutrophication as perennial species seem to tolerate rather eutrophied conditions, when suitable substrate is available. The lower limit of occurrence of many of the brown and red algal species is a good indicator of eutrophication but due to lack of suitable substrate in more eutrophied areas, especially in the depths where light becomes limiting, it is only applicable in the middle and outer archipelago areas. Furthermore, when planning monitoring programmes or setting thresholds for evaluating the ecological status of the sea, the natural variation in the lower limit of occurrence of macroalgae across sea areas is problematic and should carefully be taken into account.  相似文献   

A Field Guide to Community Based Adaptation by Tim Magee. Routledge,London, 2013, pp. x + 232 (ISBN 978‐0‐415‐51929‐8) (hbk) (ISBN 978‐0‐415‐51930‐4) (pbk).          下载免费PDF全文

Johanna Wandel 《Singapore journal of tropical geography》2015,36(2):272-274

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OSL Age Determination of Archaeological Stone Structures Using Trapped Aeolian Sediments: A Case Study from the Negev Highlands,Israel     

Andrea Junge  Johanna Lomax  Ruth Shahack‐Gross  Zachary C. Dunseth  Israel Finkelstein  Markus Fuchs 《Geoarchaeology》2016,31(6):550-563

Optically stimulated luminescence (OSL) dating is widely applied to sediments in paleoenvironmental sciences. However, there are only limited examples determining the age of archaeological stone structures by OSL using dust deposits. The age of dust deposits associated with ancient buildings may be used to date the onset of settlement (sediment below structures), settlement activity (occupation layer), or the time after a settlement had been abandoned or destroyed (sediment between collapsed roofs and walls). In this study, OSL dating is applied to establish numerical dates for settlement structures situated in the Negev Highlands, Israel. Two archaeological sites are investigated to identify their occupation history, by dating nine samples of aeolian dust trapped within the remains of ancient buildings. The OSL dating technique is applied using coarse grain quartz and a standard single‐aliquot regenerative‐dose (SAR) protocol. It was possible to date the onset of sedimentation in a later phase of the human occupation or shortly after the sites were abandoned, to 3.7 ± 0.3 ka (Intermediate Bronze Age) at the central site and to 2.7 ± 0.2 ka (Iron Age) at the ephemeral site. These results are supported by archaeological evidence gained from pottery finds and the architecture of the ancient buildings.  相似文献   

Integrated Onshore‐Offshore Investigation of a Mediterranean Layered Coastal Aquifer     

Johanna Lofi  Philippe Pezard  Frédéric Bouchette  Olivier Raynal  Pierre Sabatier  Nataliya Denchik  Arnaud Levannier  Laurent Dezileau  Raphaël Certain 《Ground water》2013,51(4):550-561

Most of the Mediterranean coastal porous aquifers are intensively exploited. Because of climatic and anthropogenic effects, understanding the physical and geological controls on groundwater distribution and flow dynamics in such aquifers is crucial. This study presents the results of a structural investigation of a system located along the coastline of the Gulf of Lions (NW Mediterranean). A key aspect of this study relies on an onshore‐offshore integrated approach combining outcrops, seismic profiles, and borehole data analysis. This multidisciplinary approach provides constraints on pore‐fluid salinity distribution and stratigraphic organization, which are crucial in assessing the modes of groundwater/seawater exchanges. Onshore, Lower Pliocene deposits dip gently seaward. They are unconformably overlain by Holocene clays in the lagoons. Offshore the Pliocene deposits either outcrop at the seabed or are buried below nonconsolidated sands infilling paleo‐valleys. Beneath the lido, the groundwater salinity distribution consists of salty pore water, overlying fresher pore water. Active circulation of groundwater masses is inferred from the geophysical results. In particular, offshore outcrops and paleo‐valleys may play an important role in salt water intrusion.  相似文献