scholarly journals 10Be and 14C data provide insight on soil mass redistribution along gentle slopes and reveal ancient human impact

Author(s):  
Francesca Calitri ◽  
Michael Sommer ◽  
W. Marijn van der Meij ◽  
Dmitry Tikhomirov ◽  
Marcus Christl ◽  
...  

Abstract Purpose Spatial and temporal patterns of past erosional events are a useful and needed information to explain observed soil patterns in different landscapes. Soil thickness reflects the overall expression of pedogenesis and erosion. Forested soils of Northern Germany exhibit varying soil thicknesses with thin soils on crest positions and buried soils at the footslope. The aim of this study is to reconstruct the complex soil mass redistribution and soil patterns of this forested area due to different periods of erosion and stability. Methods We explored the explanatory power of both 10Be (in situ and meteoric) on a hillslope and we 14C-dated buried horizons at different depths. Results The 10Be depth profiles did not show an exponential decrease with depth. They had a ‘bulge’ shape indicating clay translocation and interaction with oxyhydroxydes (meteoric 10Be), bioturbation and soil mass redistribution (in situ 10Be). The combined application of both 10Be and 14C dating revealed progressive and regressive phases of soil evolution. Although Melzower Forest is protected (same vegetation) since the past 250 years, both 10Be clearly indicated major soil mass redistribution along the investigated catena. Conclusion A strong erosion impulse must have occurred between 4.5 and 6.8 kyr BP indicating an earlier human impact on soil erosion than previously postulated (~ 3 kyr earlier). Our findings correlate in fact with the first settlements reported for this region (~ 6.8 kyr BP) and show their immediate effect on soils. The overall soil redistribution rates in this forest are surprisingly similar to those obtained from a nearby agricultural area.

2020 ◽  
Author(s):  
Francesca Calitri ◽  
Markus Egli ◽  
Michael Sommer ◽  
Dmitry Tikhomirov ◽  
Marcus Christl

<p><span>In hilly and mountainous landscapes, the bedrock is actively converted to a continuous soil mantle. The bedrock-soil interface lowers spatially at the soil production rate, and the soil acts as a layer removing sediment produced locally and transported from upslope. Forested soils of a hummocky ground moraine landscape in Northern Germany exhibit strongly varying soil thicknesses with very shallow soils on crest positions and buried soils at the footslope. We explored the explanatory power of both <sup>10</sup>Be forms (in situ and meteoric) for forest soils on a hillslope to shed light into the </span><span>complex mass redistribution. </span><span>Our main research questions were: how do meteoric and in-situ <sup>10</sup>Be compare to each other? What do they really indicate in terms of soil processes (erosion, sedimentation, reworking)? </span><span>By using both types of <sup>10</sup>Be, the dynamics of soils and related mass transports should be better traceable</span><span>. Both <sup>10</sup>Be forms were measured along three profiles at different slope positions: Hydro1 (summit), Hydro3 (shoulder), Hydro4 (backslope). Furthermore, a buried horizon was found in the profile Hydro4 at 160 cm depth and <sup>14</sup>C-dated. The distribution pattern of meteoric <sup>10</sup>Be of Hydro4 shows an inverse exponential depth profile, and an almost uniform content of in-situ <sup>10</sup>Be along the profile. Meteoric <sup>10</sup>Be indicates on the one hand that a new soil was put on top of an older, now buried soil. On the other hand, meteoric <sup>10</sup>Be is involved in pedogenetic processes and clearly exhibits clay eluviation in the topsoil and clay illuviation in the subsoil. The uniform content of the in situ <sup>10</sup>Be shows soil mixing that must have occurred during erosion and sedimentation. The<sup>14</sup>C dated buried soil horizon indicates a deposition of eroded soil material about 7 ka BP. Consequently, an increase in the in-situ <sup>10</sup>Be content towards the surface should be expect which however was not the case. The reason for this is so far unknown. Radiocarbon dating and <sup>10</sup>Be data demonstrate that strong events of soil mass redistribution in Melzower Forest are mainly a result of ancient natural events. Further measurements of fallout radionuclides (<sup>239+240</sup>Pu) showed no erosion for the last few decades in the same catchment.</span></p>


2010 ◽  
Vol 22 (4) ◽  
pp. 409-417 ◽  
Author(s):  
James G. Bockheim

AbstractSoil preservation from three glacial thermal regimes was examined in the Transantarctic Mountains (TAM) using the University of Wisconsin Antarctic Soils Database (http://nsidc.org/data/ggd221). Glacial thermal regimes included temperate (wet-based) glaciers from overriding of the TAM prior to c. 15Ma bp and subsequent polar (dry-based) glaciers. The glacial thermal regimes were distinguished from landform, sediment and erosional features. Buried soils were most common from deposition by dry-based glaciers (44 of 51 pedons). Several of these buried soils had a desert pavement intact with in situ ventifacts. Fifteen percent of the pedons contained recycled ventifacts in relict and buried soils that ranged from late Quaternary to Miocene in age, particularly in drift from dry-based glaciers (56 of 77 pedons). Overall 84% of the buried soils and 78% of the pedons with recycled ventifacts originated from dry-based glaciers. The proportion of soils with recycled clasts on a particular drift was greatest where the ratio of drift thickness to soil thickness (“recycling ratio”) was the least. These data illustrate the effectiveness of Antarctic dry-based glaciers in preserving underlying landforms and deposits, including soils. Moreover, the data imply that Antarctic glaciers have been recycling clasts for the past c. 15Ma. These findings have important implications in selecting surface boulders for cosmogenic dating.


2017 ◽  
Vol 26 (3) ◽  
pp. 179-190
Author(s):  
Igor Boyko ◽  
Liudmyla Skochko ◽  
Veronica Zhuk

Abstract The interaction features of multi-level retaining walls with soil base were researched by changing their geometric parameters and locality at the plan. During excavation of deep foundation pits it is important to choose the type of constructions which influences on the horizontal displacements. The distance between the levels of retaining walls should be based on the results of numerical modelling. The objective of this paper is to present a comparison between the data of numerical simulations and the results of the in-situ lateral tests of couple piles. The problems have been solved by using the following soil models: Coulomb-Mohr model; model, which is based on the dilatation theory; elastic-plastic model with variable stiffness parameters.


2011 ◽  
Vol 90-93 ◽  
pp. 217-221
Author(s):  
Jin Long Zhou ◽  
Qiao Li ◽  
Wei Zhong Cai

Through the investigation into composition of major shallow foundation soil mass and the correlation of mechanical indicators in this study, the regression equation of mechanical indicators of the features of local foundation soil mass and the data of in situ testing was obtained. Based on massive quantities of exploration materials, this study analyzed engineering features, distribution status, and the feasibility of silty clay to be used as the bearing layer of the pile in Layer ④2 . The analytical results showed that the silty clay with the uniform depth of over 3.5m and the cone tip resistance in static sounding of over 400MPa could be used as bearing layer of the pile. This study could provide the reference for the accurate understanding of the engineering features of soil mass, and the design and evaluation of foundation in Jiaxing City.


1998 ◽  
Vol 11 (2) ◽  
pp. 1057-1064
Author(s):  
P.R. Mahaffy ◽  
S.K. Atreya ◽  
H.B. Niemann ◽  
T.C. Owen

AbstractInsights into both the detailed composition of Jupiter’s atmosphere and unexpected local meteorological phenomena were revealed by in-situ measurements from the Galileo Probe Neutral Mass Spectrometer taken on December 7, 1995. Measurements of the neutral atmospheric composition from a pressure of 0.5 bar to approximately 21 bar revealed the mixing ratios of the major species helium and hydrogen as well as numerous minor constituents including methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. This instrument measured the isotope ratios3He/4He, D/H, and13C/12C as well as the isotopes of neon, argon, krypton, and xenon. A summary is given of progress that has been made in refining preliminary estimates of the abundances of condensable volatiles and noble gases as a result of an ongoing laboratory study using a nearly identical engineering unit. The depletion of simple condensable species to depths well below their expected condensation levels is explained by a local downdraft in the region of the probe entry. The mass spectrometer data suggests that different species may recover at different depths and this may be due to lateral mixing of Jovian air.


2021 ◽  
Author(s):  
Mark Wenig ◽  
Sheng Ye ◽  
Ying Zhu ◽  
Hanlin Zhang

<p>The problem of elevated NO<sub>2</sub> levels in cities has gained some attention in the public in recent years and has given rise to questions about the plausibility of banning diesel engines in cities, the meaning of exceedances of air quality limits and the effects of corona lock-downs on air quality to name a few. Urban air quality is typically monitored using a relatively small number of monitoring stations. Those in-situ measurements follow certain guidelines in terms of inlet height and location relative to streets, but the question remains how a limited number of point measurements can capture the spatial variability in cities. In this talk we present two measurement campaigns in Hong Kong and Munich where we utilized a combination of mobile in-situ and stationary remote sensing differential optical absorption spectroscopy (DOAS) instruments. We developed an algorithm to separate spatial and temporal patterns in order to generate pollution maps that represent average NO<sub>2</sub> exposure. </p> <p>We use those maps to identify pollution hot spots and capture the weekly cycles of on-road NO2 levels and spatial dependency of long-term changes and we analyze how on-road measurements compare to monitoring station data and how the measurement height and distance to traffic emissions have to be considered when interpreting observed concentration patterns.</p>


2013 ◽  
Vol 17 (12) ◽  
pp. 4925-4939 ◽  
Author(s):  
L. Seoane ◽  
G. Ramillien ◽  
F. Frappart ◽  
M. Leblanc

Abstract. Time series of regional 2° × 2° Gravity Recovery and Climate Experiment (GRACE) solutions have been computed from 2003 to 2011 with a 10-day resolution by using an energy integral method over Australia (112° E–156° E; 44° S–10° S). This approach uses the dynamical orbit analysis of GRACE Level 1 measurements, and specially accurate along-track K-band range rate (KBRR) residuals with a 1 μm s−1 level of errors, to estimate the total water mass over continental regions. The advantages of regional solutions are a significant reduction of GRACE aliasing errors (i.e. north–south stripes) providing a more accurate estimation of water mass balance for hydrological applications. In this paper, the validation of these regional solutions over Australia is presented, as well as their ability to describe water mass change as a response of climate forcings such as El Niño. Principal component analysis of GRACE-derived total water storage (TWS) maps shows spatial and temporal patterns that are consistent with independent data sets (e.g. rainfall, climate index and in situ observations). Regional TWS maps show higher spatial correlations with in situ water table measurements over Murray–Darling drainage basin (80–90%), and they offer a better localization of hydrological structures than classical GRACE global solutions (i.e. Level 2 Groupe de Recherche en Géodésie Spatiale (GRGS)) products and 400 km independent component analysis solutions as a linear combination of GRACE solutions provided by different centers.


1977 ◽  
Vol 14 (12) ◽  
pp. 2824-2857 ◽  
Author(s):  
G. H. Miller ◽  
J. T. Andrews ◽  
S. K. Short

A study of the stratigraphic sequence (14C and amino acid age control), marine bivalve faunal changes, and palynology of buried soils and organic-rich sediment collected from the Clyde Foreland Formation in the extensive cliff sections of the Clyde foreland, eastern Baffin Island, N.W.T., suggests the following last interglacial – Foxe (last glaciation) glacial – present interglacial sequence.(1) Cape Christian Member (ca. 130 000 years BP?)Consists of the Sledgepointer till overlain by the Cape Christian marine sediments. In situ molluscan fauna, collected from the marine sediments, contain a moderately warm bivalve assemblage. A well-developed soil that formed on the marine sediments (Cape Christian soil) contains an interglacial pollen assemblage dominated by dwarf birch. U-series dates of > 115 000 and ca. 130 000 years BP on molluscs from the Cape Christian marine sediments suggest that they were deposited during the last interglaciation, here termed the Cape Christian Interglaciation. The development of a subarctic pollen assemblage in the Cape Christian soil has not been duplicated during the present interglaciation, suggesting higher summer temperatures and perhaps a duration well in excess of 10 000 years for the last interglaciation.(2) Kuvinilk MemberConsists of fossiliferous marine sediments, locally divided by the Clyde till into upper and lower units. The Clyde till was deposited by the earliest and most extensive advance of the Foxe (last) Glaciation. Kuvinilk marine sediments both under- and overlying the Clyde till contain the pecten Chlamys islandicus, indicating that the outlet glacier advanced into a subarctic marine environment. Amino acid ratios from in situ pelecypod shells abovę and below the Clyde till are not statistically different, but contrast markedly with ratios obtained from the same species in the Cape Christian Member. Organic horizons within the Kuvinilk marine sediments contain a relatively rich pollen assemblage, although 'absolute' counts are low.(3) Kogalu Member (> 35 00014C years BP)Sediments of the Kogalu Member unconformably overlie those of the Kuvinilk Member, but are of a similar character. The dominant sediments are marine in origin, but in places are divided into upper and lower units by the Ayr Lake till. Amino acid ratios from in situ shells above and below the Ayr Lake till are indistinguishable, but substantially less than those in the Kuvinilk Member, suggesting the two members are separated by a considerable time interval. Radiocarbon dates on shells in the Kogalu marine sediments range from 33 000 to 47 700 years BP, but these may be only minimum estimates. The sea transgressed to a maximum level 70–80 m asl, coincident with the glacial maximum. Subarctic marine fauna of interstadial–interglacial character occur within the Kogalu marine sediments.(4) Eglinton Member (10 000 years BP to present)A major unconformity exists between the Kogalu and Eglinton Members. Ravenscraig marine sediments were deposited during an early Holocene marine transgression–regression cycle; the oldest dates on these sediments are ca. 10 000 years BP. Locally a vegetation mat occurs at the base or within the Ravenscraig unit. Pollen from these beds is sparse, but indicates a terrestrial vegetation assemblage as diverse as that of today. There is no evidence that Laurentide Ice reached the foreland during the last 30 000 years. Eolian sands that overlie a soil developed on the marine sediments record a late Holocene climatic deterioration. Pollen in organic-rich sediments at the base of, and within, the eolian sands record a vegetation shift in response to climatic change.


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