Warming enhances old organic carbon decomposition through altering functional microbial communities

DOE PAGES

Cheng, Lei; Zhang, Naifang; Yuan, Mengting; ...

2017-04-21

Soil organic matter (SOM) stocks contain nearly three times as much carbon (C) as the atmosphere and changes in soil C stocks may have a major impact on future atmospheric carbon dioxide concentrations and climate. Over the past two decades, much research has been devoted to examining the influence of warming on SOM decomposition in topsoil. Most SOM, however, is old and stored in subsoil. The fate of subsoil SOM under future warming remains highly uncertain. Here, by combining a long-term field warming experiment and a meta-analysis study, we showed that warming significantly increased SOM decomposition in subsoil. We alsomore » showed that a decade of warming promoted decomposition of subsoil SOM with turnover times of decades to millennia in a tall grass prairie and this effect was largely associated with shifts in the functional gene structure of microbial communities. By coupling stable isotope probing with metagenomics, we found that microbial communities in warmed soils possessed a higher relative abundance of key functional genes involved in the degradation of organic materials with varying recalcitrance than those in control soils. These findings suggest warming may considerably alter the stability of the vast pool of old SOM in subsoil, contributing to the long-term positive feedback between the C cycle and climate.« less

The attenuation of microorganisms in on-site wastewater effluent discharged into highly permeable subsoils

NASA Astrophysics Data System (ADS)

O'Luanaigh, N. D.; Gill, L. W.; Misstear, B. D. R.; Johnston, P. M.

2012-11-01

An extensive field study on percolation areas receiving both septic tank and secondary treated on-site effluents from single houses in Ireland was carried out to investigate the attenuation capacity of highly permeable subsoils with respect to E. coli bacteria and spiked bacteriophages (MS2, ΦX174 and PR772). The development of biomats across the percolation areas receiving the secondary effluent was restricted compared to the percolation area receiving septic tank effluent, promoting a much higher areal hydraulic loading which created significant differences in the potential microbiological loading to groundwater. Greatest E. coli removal in the subsoil occurred within the first 0.35 m of unsaturated subsoil for all effluent types. Analysis showed, however, that more evidence of faecal contamination occurred at depth in the subsoils receiving secondary treated effluents than that receiving septic tank effluent, despite the lower bacterial influent load. All three bacteriophages were reduced to their minimum detection limit (< 10 PFU/mL) at a depth of 0.95 m below the percolation trenches receiving septic tank effluent, although isolated incidences of ΦX174 and PR772 were measured below one trench. However again, slightly higher breakthroughs of MS2 and PR772 contamination were detected at the same depth under the trenches receiving secondary treated effluent.

The forgotten part of carbon cycling: Organic matter storage and turnover in subsoils [SUBSOM

NASA Astrophysics Data System (ADS)

Marschner, B.

2013-12-01

In the past, carbon flux measurements and modelling have mostly considered the topsoil where C-concentrations, root densities and microbial activities are generally highest. However, depending on climate zone and land use, this soil compartment contains only 30-50% of the C-stocks of the first meter. If the deeper subsoil down to 3 m is also considered, the contribution of topsoil carbon stocks to total soil C-pools is only 20-40%. Another distinct property of subsoil organic matter is its high apparent 14C age. The 14C age of bulk soil organic matter below 30 cm depth generally increases continuously indicating mean residence times of several 103 to 104 years. Large pool size and high radiocarbon age suggest that subsoil OM has accumulated at very low rates over very long time periods and therefore appears to be very stable. In a review, several hypotheses for explaining why subsoil SOM is so seemingly old and inert are presented. Then a recently granted German research unit consisting of 9 subprojects from all soil science disciplines is introduced, which addresses these questions using field measurements of C-fluxes, 14C analyses and conducting field and lab experiments. 40-60% of soil C-pools are found below 40 cm depth (Data from Jobbagy & Jackson 2000).

Warming enhances old organic carbon decomposition through altering functional microbial communities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Lei; Zhang, Naifang; Yuan, Mengting

Soil organic matter (SOM) stocks contain nearly three times as much carbon (C) as the atmosphere and changes in soil C stocks may have a major impact on future atmospheric carbon dioxide concentrations and climate. Over the past two decades, much research has been devoted to examining the influence of warming on SOM decomposition in topsoil. Most SOM, however, is old and stored in subsoil. The fate of subsoil SOM under future warming remains highly uncertain. Here, by combining a long-term field warming experiment and a meta-analysis study, we showed that warming significantly increased SOM decomposition in subsoil. We alsomore » showed that a decade of warming promoted decomposition of subsoil SOM with turnover times of decades to millennia in a tall grass prairie and this effect was largely associated with shifts in the functional gene structure of microbial communities. By coupling stable isotope probing with metagenomics, we found that microbial communities in warmed soils possessed a higher relative abundance of key functional genes involved in the degradation of organic materials with varying recalcitrance than those in control soils. These findings suggest warming may considerably alter the stability of the vast pool of old SOM in subsoil, contributing to the long-term positive feedback between the C cycle and climate.« less

Warming enhances old organic carbon decomposition through altering functional microbial communities

PubMed Central

Cheng, Lei; Zhang, Naifang; Yuan, Mengting; Xiao, Jing; Qin, Yujia; Deng, Ye; Tu, Qichao; Xue, Kai; Van Nostrand, Joy D; Wu, Liyou; He, Zhili; Zhou, Xuhui; Leigh, Mary Beth; Konstantinidis, Konstantinos T; Schuur, Edward AG; Luo, Yiqi; Tiedje, James M; Zhou, Jizhong

2017-01-01

Soil organic matter (SOM) stocks contain nearly three times as much carbon (C) as the atmosphere and changes in soil C stocks may have a major impact on future atmospheric carbon dioxide concentrations and climate. Over the past two decades, much research has been devoted to examining the influence of warming on SOM decomposition in topsoil. Most SOM, however, is old and stored in subsoil. The fate of subsoil SOM under future warming remains highly uncertain. Here, by combining a long-term field warming experiment and a meta-analysis study, we showed that warming significantly increased SOM decomposition in subsoil. We also showed that a decade of warming promoted decomposition of subsoil SOM with turnover times of decades to millennia in a tall grass prairie and this effect was largely associated with shifts in the functional gene structure of microbial communities. By coupling stable isotope probing with metagenomics, we found that microbial communities in warmed soils possessed a higher relative abundance of key functional genes involved in the degradation of organic materials with varying recalcitrance than those in control soils. These findings suggest warming may considerably alter the stability of the vast pool of old SOM in subsoil, contributing to the long-term positive feedback between the C cycle and climate. PMID:28430189

Warming enhances old organic carbon decomposition through altering functional microbial communities.

PubMed

Cheng, Lei; Zhang, Naifang; Yuan, Mengting; Xiao, Jing; Qin, Yujia; Deng, Ye; Tu, Qichao; Xue, Kai; Van Nostrand, Joy D; Wu, Liyou; He, Zhili; Zhou, Xuhui; Leigh, Mary Beth; Konstantinidis, Konstantinos T; Schuur, Edward Ag; Luo, Yiqi; Tiedje, James M; Zhou, Jizhong

2017-08-01

Soil organic matter (SOM) stocks contain nearly three times as much carbon (C) as the atmosphere and changes in soil C stocks may have a major impact on future atmospheric carbon dioxide concentrations and climate. Over the past two decades, much research has been devoted to examining the influence of warming on SOM decomposition in topsoil. Most SOM, however, is old and stored in subsoil. The fate of subsoil SOM under future warming remains highly uncertain. Here, by combining a long-term field warming experiment and a meta-analysis study, we showed that warming significantly increased SOM decomposition in subsoil. We also showed that a decade of warming promoted decomposition of subsoil SOM with turnover times of decades to millennia in a tall grass prairie and this effect was largely associated with shifts in the functional gene structure of microbial communities. By coupling stable isotope probing with metagenomics, we found that microbial communities in warmed soils possessed a higher relative abundance of key functional genes involved in the degradation of organic materials with varying recalcitrance than those in control soils. These findings suggest warming may considerably alter the stability of the vast pool of old SOM in subsoil, contributing to the long-term positive feedback between the C cycle and climate.

Engineering geological mapping in Wallonia (Belgium) : present state and recent computerized approach

NASA Astrophysics Data System (ADS)

Delvoie, S.; Radu, J.-P.; Ruthy, I.; Charlier, R.

2012-04-01

An engineering geological map can be defined as a geological map with a generalized representation of all the components of a geological environment which are strongly required for spatial planning, design, construction and maintenance of civil engineering buildings. In Wallonia (Belgium) 24 engineering geological maps have been developed between the 70s and the 90s at 1/5,000 or 1/10,000 scale covering some areas of the most industrialized and urbanized cities (Liège, Charleroi and Mons). They were based on soil and subsoil data point (boring, drilling, penetration test, geophysical test, outcrop…). Some displayed data present the depth (with isoheights) or the thickness (with isopachs) of the different subsoil layers up to about 50 m depth. Information about geomechanical properties of each subsoil layer, useful for engineers and urban planners, is also synthesized. However, these maps were built up only on paper and progressively needed to be updated with new soil and subsoil data. The Public Service of Wallonia and the University of Liège have recently initiated a study to evaluate the feasibility to develop engineering geological mapping with a computerized approach. Numerous and various data (about soil and subsoil) are stored into a georelational database (the geotechnical database - using Access, Microsoft®). All the data are geographically referenced. The database is linked to a GIS project (using ArcGIS, ESRI®). Both the database and GIS project consist of a powerful tool for spatial data management and analysis. This approach involves a methodology using interpolation methods to update the previous maps and to extent the coverage to new areas. The location (x, y, z) of each subsoil layer is then computed from data point. The geomechanical data of these layers are synthesized in an explanatory booklet joined to maps.

The treatment performance of different subsoils in Ireland receiving on-site wastewater effluent.

PubMed

Gill, L W; O'Súlleabháin, C; Misstear, B D R; Johnston, P J

2007-01-01

Current Irish guidelines require a comprehensive site assessment of a percolation area for wastewater disposal before planning permission is granted for dwellings in rural areas. For a site to be deemed suitable, the subsoil must have a percolation value equivalent to a field saturated hydraulic conductivity in the range 0.08 to 4.2 m d(-1) using a falling head percolation test. A minimum of 1.2 m of unsaturated subsoil must also exist below the invert of the percolation area receiving effluent from a septic tank (or 0.6 m for secondary treated effluent). During a 2-yr period, the three-dimensional performance of four percolation areas treating domestic wastewater was monitored. At each site samples were taken at 0, 10, and 20 m along each of the four percolation trenches at depths of 0.3, 0.6, and 1.0 m below each trench to ascertain the attenuation effects of the unsaturated subsoil. The two sites with septic tanks installed performed at least as well as the other two sites with secondary treatment systems installed and appeared to discharge a better quality effluent in terms of nutrient load. An average of 2.1 and 6.8 g total N d(-1) remained after passing through 1-m depth of subsoil beneath the trenches receiving septic tank effluent compared with 12.7 and 16.7 g total N d(-1) on the sites receiving secondary effluent. The research also indicates that the septic tank effluent was of an equivalent quality to the secondary treated effluent in terms of indicator bacteria (E. coli) after percolating through 0.6-m depth of unsaturated subsoil.

A tracer experiment to study flow paths of water in a forest soil

NASA Astrophysics Data System (ADS)

Feyen, H.; Wunderli, H.; Wydler, H.; Papritz, A.

1999-12-01

This contribution discusses a tracer experiment, which was performed to study the flow paths of water in a macroporous forest soil. The experiment was performed in the framework of a study on the cycling of nitrogen in forested Prealpine catchments, in which losses of nitrate from virtually pristine areas were observed. Two soil plots with distinct micro-topography and top-soil were investigated: a well drained mor humus on a mound and a wet muck humus in a small depression. To reveal the effect of the soil horizons on the flow regime, tracers were applied both onto the soil surface and injected into the sub-soil. Tracers injected directly into the gleyic sub-soil reached the outlet (at a distance of 3.3 m) about 1000 times faster than could be expected from the saturated hydraulic conductivity of the soil matrix. Peak concentrations were observed after 18 (muck humus, tracer recovery 31%) to 70 min (mor humus, tracer recovery 40%). The peak concentration was 10 times smaller on the drier mor humus plot as compared to the muck humus. The mobile water content of the sub-soil varied between 0.5 (muck humus) and 1.3% (mor humus) of the total available soil water. The discrepancy in residence time, peak concentration and volume of mobile water between both sub-soils can be attributed to the differently structured sub-soil (longer travel distance and mixing volume in the drier mor humus). Tracers applied onto the soil surface resulted in a much slower breakthrough (tracer peaks after 400-700 min). Thus, in contrast to the sub-soil, flow through the matrix was the predominating transport process in the upper humus layers of both plots.

Distribution of enzyme activity hotspots induced by earthworms in top- and subsoil

NASA Astrophysics Data System (ADS)

Hoang, D. T. T.

2016-12-01

Earthworms (Lumbricus terrestris L.) not only affect soil physics, but they also boost microbial activities and consequently create important hotspots of microbial mediated carbon and nutrient turnover through their burrowing activity. However, it is still unknown to which extend earthworms change the enzyme distribution and activity inside their burrows in top- and subsoil horizons. We hypothesized that earthworm burrows, which are enriched in available substrates, have higher percentage of enzyme activity hotspots than soil without earthworms, and that enzyme activities decreased with increasing depth because of the increasing recalcitrance of organic matter in subsoil. We visualized enzyme distribution inside and outside of worm burrows (biopores) by in situ soil zymography and measured enzyme kinetics of 6 enzymes - β-glucosidase (GLU), cellobiohydrolase (CBH), xylanase (XYL), chitinase (NAG), leucine aminopeptidase (LAP) and acid phosphatase (APT) - in pore and bulk soil material up to 105 cm. Zymography showed a heterogeneous distribution of hotspots in worm burrows. The hotspot areas was 2.4 to 14 times larger in the burrows than in soil without earthworms. However, the dispersion index of hotspot distribution showed more aggregated hotspots in soil without earthworms than in soil with earthworms and burrow wall. Enzyme activities decreased with depth, by a factor of 2 to 8 due to fresh C input from the soil surface. Compared to bulk soil, enzyme activities in topsoil biopores were up to 11 times higher for all enzymes, but in the subsoil activities of XYL, NAG and APT were lower in earthworm biopores than bulk soil. In conclusion, hotspots were twice as concentrated close to earthworm burrows as in surrounding soil. Earthworms exerted stronger effects on enzyme activities in biopores in the topsoil than in subsoil. Keywords: Earthworms, hotspots, enzyme activities, enzyme distribution, subsoil

Assessment of the impact of traditional septic tank soakaway systems on water quality in Ireland.

PubMed

Keegan, Mary; Kilroy, Kate; Nolan, Daniel; Dubber, Donata; Johnston, Paul M; Misstear, Bruce D R; O'Flaherty, Vincent; Barrett, Maria; Gill, Laurence W

2014-01-01

One of the key threats to groundwater and surface water quality in Ireland is the impact of poorly designed, constructed or maintained on-site wastewater treatment systems. An extensive study was carried out to quantify the impact of existing sites on water quality. Six existing sites, consisting of a traditional septic tank and soakaway system, located in various ranges of subsoil permeabilities were identified and monitored to determine how well they function under varying subsoil and weather conditions. The preliminary results of the chemical and microbiological pollutant attenuation in the subsoil of the systems have been assessed and treatment performance evaluated, as well as impact on local surface water and groundwater quality. The source of any faecal contamination detected in groundwater, nearby surface water and effluent samples was confirmed by microbial source tracking. From this, it can be seen that the transport and treatment of percolate vary greatly depending on the permeability and composition of the subsoil.

Nutrient loading on subsoils from on-site wastewater effluent, comparing septic tank and secondary treatment systems.

PubMed

Gill, L W; O'Luanaigh, N; Johnston, P M; Misstear, B D R; O'Suilleabhain, C

2009-06-01

The performance of six separate percolation areas was intensively monitored to ascertain the attenuation effects of unsaturated subsoils with respect to on-site wastewater effluent: three sites receiving septic tank effluent, the other three sites receiving secondary treated effluent. The development of a biomat across the percolation areas receiving secondary treated effluent was restricted on these sites compared to those sites receiving septic tank effluent and this created significant differences in terms of the potential nitrogen loading to groundwater. The average nitrogen loading per capita at 1.0m depth of unsaturated subsoil equated to 3.9 g total-N/d for the sites receiving secondary treated effluent, compared to 2.1 g total-N/d for the sites receiving septic tank effluent. Relatively high nitrogen loading was, however, found on the septic tank sites discharging effluent into highly permeable subsoil that counteracted any significant denitrification. Phosphorus removal was generally very good on all of the sites although a clear relationship to the soil mineralogy was determined.

Current state and problems of integrated development of mineral resources base in Russia

NASA Astrophysics Data System (ADS)

Filimonova, I. V.; Eder, L. V.; Mishenin, M. V.; Mamakhatov, T. M.

2017-09-01

The article deals with the issues of integrated development of subsoil resources taking into account the actual problems facing the Russian oil and gas complex. The key factors determining the need for integrated development of subsoil resources have been systematized and investigated. These factors are the change of the hydrocarbon resource base quality, the improvement of the depletion degree of basic (unique and major) oil fields, the increase in the number of small and smallest oil fields discovered and introduced into development, the increased capital intensity and the riskiness of geological exploration, and the territorial location of new subsoil use facilities.

Biochars impact on water infiltration and water quality through a compacted subsoil layer

USDA-ARS?s Scientific Manuscript database

Soils in the Southeastern United States Coastal Plain region frequently have a compacted subsoil layer, which is a barrier for water movement. Four different biochars were evaluated to increase water movement through a compacted horizon from a Norfolk soil (fine-loamy, kaolinitic, thermic, Typic Ka...

Biochar impact on water infiltration and water quality through a compacted subsoil layer

EPA Science Inventory

Soils in the SE USA Coastal Plain region frequently have a compacted subsoil layer (E horizon), which is a barrier for water infiltration. Four different biochars were evaluated to increase water infiltration through a compacted horizon from a Norfolk soil (fine-loamy, kaolinitic...

MA_MISS and terrestrial analogues for Mars

NASA Astrophysics Data System (ADS)

De Sanctis, M. C.; De Angelis, S.; Ammannito, E.; Di Iorio, T.; Carli, C.; Frigeri, A.; Boccaccini, A.; Battistelli, E.; Mugnolo, R.; MA MISS Team

2012-09-01

The MA_MISS instrument (Mars Multispectral Imager for Subsurface Studies) is a VIS-NIR spectrometer devoted to study the Martian subsoil within the ExoMars mission. This miniaturized spectrometer is integrated in drilling system of the ExoMars Pasteur Rover, and will investigate the Martian subsoil down to 2 m, in the spectral range 0.4 - 2.2 μm [1,2]. It will provide important information regarding the composition and mineralogy of the Martian subsoil, whose materials are expected to be less altered by erosion and other exogenous processes than surface rocks. With a view to doing laboratory spectroscopic measurements with the instrument breadboard, we performed preliminary laboratory measurements on Mars analogues using a spectrophotometer coupled with a goniometer.

Effects of disking, bedding, and subsoiling on survival and growth of three oak species in central Mississippi

Treesearch

J. Paul Jeffreys; Emily B. Schultz; Thomas G. Matney; W. Cade Booth; Jason M. Morris

2010-01-01

A replicated split-plot design experiment to evaluate the effects of three site preparation methods (disking, bedding, and subsoiling plus bedding) on survival and growth of three oak species (cherrybark, Quercus pagoda Raf.; Shumard, Quercus shumardii Buckl.; and Nuttall, Quercus texana Buckl.) was established...

Biochar impact on improving root growth and water retention capacity in Norfolk hard setting subsoil layer

USDA-ARS?s Scientific Manuscript database

The Norfolk soil series is a well-drained soil used commonly for agricultural production in the Eastern Carolinas. Certain profile features such as a hard setting subsoil layer with high bulk density, low water holding capacity and meager soil fertility characteristics makes this soil less producti...

Ameliorating effects of designer biochars in a hard-setting subsoil layer: soil fertility and plant biomass

USDA-ARS?s Scientific Manuscript database

Soils in the southeastern U.S. Coastal Plain region have meager soil fertility and frequently have compacted subsoil layers (E horizon). Designer biochar has gained global interest as an amendment to improve the fertility, chemical, and physical properties of degraded agricultural soils. We hypothes...

30 CFR 816.22 - Topsoil and subsoil.

Code of Federal Regulations, 2014 CFR

2014-07-01

... § 816.22 Topsoil and subsoil. (a) Removal. (1)(i) All topsoil shall be removed as a separate layer from... paragraph (b) of this section shall be removed as a separate layer from the area to be disturbed, and... soil medium is equal to, or more suitable for sustaining vegetation than, the existing topsoil, and the...

30 CFR 816.22 - Topsoil and subsoil.

Code of Federal Regulations, 2012 CFR

2012-07-01

... § 816.22 Topsoil and subsoil. (a) Removal. (1)(i) All topsoil shall be removed as a separate layer from... paragraph (b) of this section shall be removed as a separate layer from the area to be disturbed, and... soil medium is equal to, or more suitable for sustaining vegetation than, the existing topsoil, and the...

30 CFR 816.22 - Topsoil and subsoil.

Code of Federal Regulations, 2013 CFR

2013-07-01

... § 816.22 Topsoil and subsoil. (a) Removal. (1)(i) All topsoil shall be removed as a separate layer from... paragraph (b) of this section shall be removed as a separate layer from the area to be disturbed, and... soil medium is equal to, or more suitable for sustaining vegetation than, the existing topsoil, and the...

30 CFR 817.22 - Topsoil and subsoil.

Code of Federal Regulations, 2014 CFR

2014-07-01

... ACTIVITIES § 817.22 Topsoil and subsoil. (a) Removal. (1)(i) All topsoil shall be removed as a separate layer... accordance with paragraph (b) of this section shall be removed as a separate layer from the area to be... that the resulting soil medium is equal to, or more suitable for sustaining vegetation than, the...

30 CFR 817.22 - Topsoil and subsoil.

Code of Federal Regulations, 2012 CFR

2012-07-01

... ACTIVITIES § 817.22 Topsoil and subsoil. (a) Removal. (1)(i) All topsoil shall be removed as a separate layer... accordance with paragraph (b) of this section shall be removed as a separate layer from the area to be... that the resulting soil medium is equal to, or more suitable for sustaining vegetation than, the...

30 CFR 817.22 - Topsoil and subsoil.

Code of Federal Regulations, 2013 CFR

2013-07-01

... ACTIVITIES § 817.22 Topsoil and subsoil. (a) Removal. (1)(i) All topsoil shall be removed as a separate layer... accordance with paragraph (b) of this section shall be removed as a separate layer from the area to be... that the resulting soil medium is equal to, or more suitable for sustaining vegetation than, the...

Extraction of soil solution by drainage centrifugation-effects of centrifugal force and time of centrifugation on soil moisture recovery and solute concentration in soil moisture of loess subsoils.

PubMed

Fraters, Dico; Boom, Gerard J F L; Boumans, Leo J M; de Weerd, Henk; Wolters, Monique

2017-02-01

The solute concentration in the subsoil beneath the root zone is an important parameter for leaching assessment. Drainage centrifugation is considered a simple and straightforward method of determining soil solution chemistry. Although several studies have been carried out to determine whether this method is robust, hardly any results are available for loess subsoils. To study the effect of centrifugation conditions on soil moisture recovery and solute concentration, we sampled the subsoil (1.5-3.0 m depth) at commercial farms in the loess region of the Netherlands. The effect of time (20, 35, 60, 120 and 240 min) on recovery was studied at two levels of the relative centrifugal force (733 and 6597g). The effect of force on recovery was studied by centrifugation for 35 min at 117, 264, 733, 2932, 6597 and 14,191g. All soil moisture samples were chemically analysed. This study shows that drainage centrifugation offers a robust, reproducible and standardised way for determining solute concentrations in mobile soil moisture in silt loam subsoils. The centrifugal force, rather than centrifugation time, has a major effect on recovery. The maximum recovery for silt loams at field capacity is about 40%. Concentrations of most solutes are fairly constant with an increasing recovery, as most solutes, including nitrate, did not show a change in concentration with an increasing recovery.

Fine resolution map of top- and subsoil carbon sequestration potential in France.

PubMed

Chen, Songchao; Martin, Manuel P; Saby, Nicolas P A; Walter, Christian; Angers, Denis A; Arrouays, Dominique

2018-07-15

Although soils have a high potential to offset CO 2 emissions through its conversion into soil organic carbon (SOC) with long turnover time, it is widely accepted that there is an upper limit of soil stable C storage, which is referred to SOC saturation. In this study we estimate SOC saturation in French topsoil (0-30cm) and subsoil (30-50cm), using the Hassink equation and calculate the additional SOC sequestration potential (SOC sp ) by the difference between SOC saturation and fine fraction C on an unbiased sampling set of sites covering whole mainland France. We then map with fine resolution the geographical distribution of SOC sp over the French territory using a regression Kriging approach with environmental covariates. Results show that the controlling factors of SOC sp differ from topsoil and subsoil. The main controlling factor of SOCsp in topsoils is land use. Nearly half of forest topsoils are over-saturated with a SOC sp close to 0 (mean and standard error at 0.19±0.12) whereas cropland, vineyard and orchard soils are largely unsaturated with degrees of C saturation deficit at 36.45±0.68% and 57.10±1.64%, respectively. The determinant of C sequestration potential in subsoils is related to parent material. There is a large additional SOC sp in subsoil for all land uses with degrees of C saturation deficit between 48.52±4.83% and 68.68±0.42%. Overall the SOCsp for French soils appears to be very large (1008Mt C for topsoil and 1360Mt C for subsoil) when compared to previous total SOC stocks estimates of about 3.5Gt in French topsoil. Our results also show that overall, 176Mt C exceed C saturation in French topsoil and might thus be very sensitive to land use change. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Reflecting on the structure of soil classification systems: insights from a proposal for integrating subsoil data into soil information systems

NASA Astrophysics Data System (ADS)

Dondeyne, Stefaan; Juilleret, Jérôme; Vancampenhout, Karen; Deckers, Jozef; Hissler, Christophe

2017-04-01

Classification of soils in both World Reference Base for soil resources (WRB) and Soil Taxonomy hinges on the identification of diagnostic horizons and characteristics. However as these features often occur within the first 100 cm, these classification systems convey little information on subsoil characteristics. An integrated knowledge of the soil, soil-to-substratum and deeper substratum continuum is required when dealing with environmental issues such as vegetation ecology, water quality or the Critical Zone in general. Therefore, we recently proposed a classification system of the subsolum complementing current soil classification systems. By reflecting on the structure of the subsoil classification system which is inspired by WRB, we aim at fostering a discussion on some potential future developments of WRB. For classifying the subsolum we define Regolite, Saprolite, Saprock and Bedrock as four Subsolum Reference Groups each corresponding to different weathering stages of the subsoil. Principal qualifiers can be used to categorize intergrades of these Subsoil Reference Groups while morphologic and lithologic characteristics can be presented with supplementary qualifiers. We argue that adopting a low hierarchical structure - akin to WRB and in contrast to a strong hierarchical structure as in Soil Taxonomy - offers the advantage of having an open classification system avoiding the need for a priori knowledge of all possible combinations which may be encountered in the field. Just as in WRB we also propose to use principal and supplementary qualifiers as a second level of classification. However, in contrast to WRB we propose to reserve the principal qualifiers for intergrades and to regroup the supplementary qualifiers into thematic categories (morphologic or lithologic). Structuring the qualifiers in this manner should facilitate the integration and handling of both soil and subsoil classification units into soil information systems and calls for paying attention to these structural issues in future developments of WRB.

Meta-analysis of pesticide sorption in subsoils

NASA Astrophysics Data System (ADS)

Jarvis, Nicholas

2017-04-01

It has been known for several decades that sorption koc values tend to be larger in soils that are low in organic carbon (i.e. subsoils). Nevertheless, in a regulatory context, the models used to assess leaching of pesticides to groundwater still rely on a constant koc value, which is usually measured on topsoil samples. This is mainly because the general applicability of any improved model approach that is also simple enough to use for regulatory purposes has not been demonstrated. The objective of this study was therefore first to summarize and generalize available literature data in order to assess the magnitude of any systematic increase of koc values in subsoil and to test an alternative model of subsoil sorption that could be useful in pesticide risk assessment and management. To this end, a database containing the results of batch sorption experiments for pesticides was compiled from published studies in the literature, which placed at least as much emphasis on measurements in subsoil horizons as in topsoil. The database includes 967 data entries from 46 studies and for 34 different active substances (15 non-ionic compounds, 13 weak acids, 6 weak bases). In order to minimize pH effects on sorption, data for weak acids and bases were only included if the soil pH was more than two units larger than the compound pKa. A simple empirical model, whereby the sorption constant is given as a power law function of the soil organic carbon content, gave good fits to most data sets. Overall, the apparent koc value, koc(app), for non-ionic compounds and weak bases roughly doubled as the soil organic carbon content decreased by a factor of ten. The typical increase in koc(app) was even larger for weak acids: on average koc(app) increased by a factor of six as soil organic carbon content decreased by a factor of ten. These results suggest the koc concept currently used in leaching models should be replaced by an alternative approach that gives a more realistic representation of pesticide sorption in subsoil. The model tested in this study appears to be widely applicable and simple enough to parameterize for risk assessment purposes. However, more data on subsoil sorption should first be included in the analysis to enable reliable estimation of worst-case percentile values of the power law exponent in the model.

Time course of soil carbon storage, 15N and radiocarbon signature in top- and subsoil of a 60-years agricultural field trial - indications for compensating effects of carbon input and turnover

NASA Astrophysics Data System (ADS)

Leifeld, Jens; Conen, Franz; Oberholzer, Hans Rudolf; Jochen, Mayer

2014-05-01

Soil carbon dynamics are controlled by the delicate balance between carbon inputs and outputs which both are co-regulated by land use and management (LUM) as important anthropogenic drivers. Upon land use change to cropland carbon stocks generally tend to decline but often the contribution of two opposing factors, namely changes in input and decomposition rates, to soil carbon stock changes is indistinguishable. Here we report on an ongoing cropland experiment in Zurich, Switzerland, named ZOFE (Zurich Organic Fertilization Experiment), established on former grassland in 1949. ZOFE encompasses a range of mineral and organic fertilization practices and a zero fertilizer treatment as control. The experiment has a block design with five replicates per treatment. We make use of productivity and fertilization gradients in selected treatments of the ZOFE trial to evaluate how low or high inputs (induced by differential yields and organic fertilization) may affect soil organic carbon storage and transformation. For the most recent sampling that also included subsoil down to 0.9 m, all properties were measured for every single replicate. Topsoil carbon storage declined after grassland conversion at rates of c. 0.2 t C ha-1 a-1, particularly in treatments with mineral fertilizer and high yields, and without fertilization and low yields. Organic matter amendments such as manure or compost could partially offset but not fully compensate some of the topsoil carbon loss. Over time the soil's delta 15N signature declined as well, probably due to increased atmospheric nitrogen deposition. It increased from the top- to the subsoil, indicating increasing microbial transformation, particularly with manure added. The soil's radiocarbon signature revealed distinct bomb peak patterns in all treatments but only in the topsoil. The 14C data confirmed that with higher productivity more recent organic matter was incorporated, both in top and subsoil. Because, in contrast to topsoil, subsoil carbon storage was similar among treatments, the results tentatively indicate that in the ZOFE trial higher subsoil carbon inputs, owing to high productivity and additional organic amendments, do not enhance subsoil carbon storage but higher inputs are counterbalanced by faster soil organic matter decomposition.

Comparing REE distribution in GEMAS agricultural soils and FOREGS topsoils-subsoils in Italy and Sweden

NASA Astrophysics Data System (ADS)

Petrosino, Paola; Sadeghi, Martiya; Andersson, Madelen; Albanese, Stefano; Dinelli, Enrico; Valera, Paolo; Ladenberger, Anna; Morris, George; Uhlbäck, Jo; Lima, Annamaria; De Vivo, Benedetto

2014-05-01

Scientific interest on Rare Earth Elements (REEs)-bearing media is increasing as a consequence of the rapidly growing demand of these important chemical resources, which are currently used in a large number of technical applications. In this study, Italian and Swedish REE data from the FOREGS database on topsoil and subsoils samples have been compared to the distribution of REEs in the GEMAS samples of agricultural soil (Ap), pertaining to regularly ploughed land to a depth of 20 cm. Principal Component Analysis (PCA) was carried out to identify patterns within both data sets. Investigation of the spatial distribution of REEs in FOREGS topsoil-subsoil and GEMAS Ap media for both countries revealed the prominent role of the geogenic component in the general REE geochemical pattern of the three solid media. Despite a similar REE content in the underlying parent material or bedrocks (alkaline igneous rocks, both intrusive and effusive in Italy, alkaline granites and pegmatites in Sweden), several distinct differences emerged between the two countries driven by climate, topography, age of the rock units and sediments, presence of mineralisations, type of soils and presence of glacial deposits. GEMAS agricultural soils form both countries show higher REEs contents than the corresponding subsoils and topsoils, which could be ascribed to the analytical method specifically set for REEs and the last generation ICP-MS instrument used by SGS Lab to analyze REEs in Ap soils. The REE content in Italian topsoil and subsoil is similar and there is a good agreement between the topsoils and Ap soils, which were collected from similar depth. Swedish subsoil is on the contrary more enriched in REEs with respect to topsoil, and Ap soils even display REE contents higher than subsoils. This anomalous REE concentrations in agricultural soil may originate from the fact that most of the arable land in Sweden has been located on glacial and postglacial deposits, rich in clay which has tendency to accumulate secondary REEs. We concluded that the fingerprints of anthropic activity due to agricultural activities does not influence the geogenic signal. Both in Italy and Sweden, in fact, REE trends in GEMAS agricultural soils are well comparable with those obtained for FOREGS soils sampled from unoccupied and undisturbed regions.

Carbon turnover in topsoil and subsoil: The microbial response to root litter additions and different environmental conditions in a reciprocal soil translocation experiment

NASA Astrophysics Data System (ADS)

Preusser, Sebastian; Poll, Christian; Marhan, Sven; Kandeler, Ellen

2017-04-01

At the global scale, soil organic carbon (SOC) represents the largest active terrestrial organic carbon (OC) pool. Carbon dynamics in subsoil, however, vary from those in topsoil with much lower C concentrations in subsoil than in topsoil horizons, although more than 50 % of SOC is stored in subsoils below 30 cm soil depth. In addition, microorganisms in subsoil are less abundant, more heterogeneously distributed and the microbial communities have a lower diversity than those in topsoil. Especially in deeper soil, the impact of changes in habitat conditions on microorganisms involved in carbon cycling are largely unexplored and consequently the understanding of microbial functioning is limited. A reciprocal translocation experiment allowed us to investigate the complex interaction effects of altered environmental and substrate conditions on microbial decomposer communities in both topsoil and subsoil habitats under in situ conditions. We conducted this experiment with topsoil (5 cm soil depth) and subsoil (110 cm) samples of an acid and sandy Dystric Cambisol from a European beech (Fagus sylvatica L.) forest in Lower Saxony, Germany. In total 144 samples were buried into three depths (5 cm, 45 cm and 110 cm) and 13C-labelled root litter was added to expose the samples to different environmental conditions and to increase the substrate availability, respectively. Samples were taken in three month intervals up to a maximum exposure time of one year to follow the temporal development over the experimental period. Analyses included 13Cmic and 13C PLFA measurements to investigate the response of microbial abundance, community structure and 13C-root decomposition activity under the different treatments. Environmental conditions in the respective soil depths such as soil temperature and water content were recorded throughout the experimental period. All microbial groups (gram+ and gram- bacteria, fungi) showed highest relative 13C incorporation in 110 cm depth and samples with root addition had generally higher microbial abundances than those with no root addition. Here, especially fungi benefited from the additional carbon source with highly increased abundances in all incorporation depths. Also the altered environmental conditions in the different incorporation depths significantly influenced the different microbial groups. The steepest decrease with depth was detected in fungal abundance, while bacteria were less affected and increased in relative abundance in soil samples incorporated into subsoil layers. The highest seasonal variability in microbial abundance, however, was determined in 5 cm incorporation depth demonstrating the higher amplitude in micro-climatic and micro-environmental conditions in this near-surface soil habitat. In summary, this experiment demonstrated that carbon quality and quantity are the main factors restricting fungal abundance in deeper soil layers, while bacterial decomposer communities are adapted to a wider range of habitat conditions.

Progress report: effects of subsoiling study, Milford Ranger District, Plumas National Forest

Treesearch

John T. Kliejunas; William J. Otrosina

1997-01-01

Subsoiling is becoming a standard practice to alleviate detrimental soil compaction following biomass harvesting in eastside pine and mixed conifer forests in California. Compaction of soil following the harvesting can be detrimental to growth of residuals, to establishment of natural regeneration, and may change long-term soil productivity. The short and long-term...

System for plotting subsoil structure and method therefor

NASA Technical Reports Server (NTRS)

Narasimhan, K. Y.; Nathan, R.; Parthasarathy, S. P. (Inventor)

1980-01-01

Data for use in producing a tomograph of subsoil structure between boreholes is derived by pacing spaced geophones in one borehole, on the Earth surface if desired, and by producing a sequence of shots at spaced apart locations in the other borehole. The signals, detected by each of the geophones from the various shots, are processed either on a time of arrival basis, or on the basis of signal amplitude, to provide information of the characteristics of a large number of incremental areas between the boreholes. Such information is useable to produce a tomograph of the subsoil structure between the boreholes. By processing signals of relatively high frequencies, e.g., up to 100 Hz, and by closely spacing the geophones, a high resolution tomograph can be produced.

The development of a code of practice for single house on-site wastewater treatment in Ireland.

PubMed

Gill, L W

2011-01-01

The performance of six separate percolation areas was intensively monitored to ascertain the attenuation effects of unsaturated subsoils with respect to on-site wastewater effluent: three sites receiving septic tank effluent, the other three sites receiving secondary treated effluent. The development of a biomat across the percolation areas receiving secondary treated effluent was restricted on these sites compared to those sites receiving septic tank effluent. This created significant differences in terms of the hydraulic loading on the percolation areas with implications for the transport and attenuation of indicator microorganisms and nitrogen down through the subsoils and into the groundwater. The results of this work have formed a large input into the production of a new Code of Practice Wastewater Treatment and Disposal Systems Serving Single Houses. This has led to changes in the design of on-site hydraulic loading from 180 L per capita per day (L/c.d) down to 150 L/c.d. The range of acceptable subsoils receiving septic tank effluent has narrowed for more highly permeable subsoils following a series of tracer studies using bacteriophages. However, the range has been extended for lower permeability subsoils (range 0.08 down to 0.06 m/d) receiving secondary treated effluent in order to encourage the effluent to spread further along the trenches. The maximum individual length of percolation trenches receiving secondary effluent has also been reduced to 10 m to encourage dispersion on a wider area. This paper thus highlights how research can directly feed into a Code of Practice.

[Effects of tillage pattern on the flag leaf senescence and grain yield of winter wheat under dry farming].

PubMed

Huang, Ming; Wu, Jin-Zhi; Li, You-Jun; Yao, Yu-Qing; Zhang, Can-Jun; Cai, Dian-Xiong; Jin, Ke

2009-06-01

A field experiment was conducted to study the effects of different tillage patterns, i.e., deep plowing once, no-tillage, subsoiling, and conventional tillage, on the flag leaf senescence and grain yield of winter wheat, as well as the soil moisture and nutrient status under dry farming. No-tillage and subsoiling increased the SOD and POD activities and the chlorophyll and soluble protein contents, decreased the MDA and O2(-.) contents, and postponed the senescence of flag leaf. Under non-tillage and subsoiling, the moisture content in 0-40 cm soil layer at anthesis and grain-filling stages was decreased by 4.13% and 6.23% and by 5.50% and 9.27%, respectively, and the contents of alkali-hydrolysable N, available P, and available K in this soil layer also increased significantly, compared with those under conventional tillage. Deep plowing once decreased the moisture content and increased the nutrients contents in 0-40 cm soil layer, but the decrement and increment were not significant. The post-anthesis biomass, post-anthesis dry matter translocation rate, and grain yield under no-tillage and subsoiling were 4.34% and 4.76%, 15.56% and 13.51%, and 10.22% and 9.26% higher than those under conventional tillage, respectively. It could be concluded that no-tillage and subsoiling provided better soil conditions for the post-anthesis growth of winter wheat, under which, the flag leaf senescence postponed, post-anthesis dry matter accumulation and translocation accelerated, and grain yield increased significantly, being the feasible tillage practices in dry farming winter wheat areas.

Effects of subsoiling on woody roots of Jeffrey pines on two different soil types

Treesearch

W.J. Otrosina; Shi-Jean S. Sung

1995-01-01

This study was initiated to determine the long term effects of subsoiling to alleviate soil compaction due to use of mechanized harvesting equipment in forest stands. Two stands having a predominance of 90 to 110 year old Jeffrey pines (Pinus jeffreyi Grev. & Balf.) were selected for this investigation. Each stand was located on the Milford...

Evaluating subsoiling and herbaceous weed control on shortleaf pine planted in retired farm land

Treesearch

John D. Kushla

2010-01-01

In March 2005, shortleaf pine was planted on retired fields of the Mississippi Agriculture and Forestry Experiment Station in Holly Springs. The objectives were to evaluate subsoiling and herbaceous weed control on first year seedling stocking, survival, and size. First year seedling measurements were made on stocking, survival, and size. Only results for first year...

Fertilizer and Mulch Improves Yellow-Poplar Growth on Exposed harsells Subsoils

Treesearch

John K. Francis

1977-01-01

Fertilizing and mulching of eroded Hartsells soil increased height and diameter of yellow-poplars. To see if chemical infertility of exposed Hartsells subsoils limits yellow-poplar growth and to test fertilizer and mulch as remedial agents, seedlings were planted on undisturbed soil, soil with the topsoil removed, and soil with the topsoil removed but mulched with leaf...

Attenuation of contaminants of coal pile leachate by interaction with subsoil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghuman, G.S.; Denham, M.E.

1996-09-01

Increased use of coal as energy source has resulted in its greater outdoor storage at electrical generation sites. Coal pile runoff (CPR) with its high concentrations of Fe, Al and sulfate leaches into subsoil and may adversely affect the quality of groundwater. During the summer, 1995, this study was conducted to determine the removal of CPR contaminants by subsoil around D-area electric plant at Savannah River Site (SRS). Groundwater samples from five monitoring wells were analyzed for physical and chemical parameters. Hydrolab Surveyor, TOC Analyzer, Dionex Ion Chromatograph and ICP-ES instruments were used for analysis. Results showed appreciable removal ofmore » CPR contaminants, sulfate, Fe, Al, Cr, Mn and Ni by the upper subsoil near the pile. The reductions in the concentrations of major contaminants in the distant wells relative to the near wells were from 12,947 to 1293 mg/L for sulfate, from 3.138 to 42 mg/L for Fe, and from 593 to 119 mg/L for Al. The study revealed the capacity of soil system to retain toxic elements of CPR leachate, which may lead to remedial actions.« less

The potential of carbon and nitrogen isotopes to conservatively discriminate between subsoil sediment sources

NASA Astrophysics Data System (ADS)

Laceby, J. Patrick; Olley, Jon

2013-04-01

Moreton Bay, in South East Queensland, Australia, is a Ramsar wetland of international significance. A decline of the bay's ecosystem health has been primarily attributed to sediments and nutrients from catchment sources. Sediment budgets for three catchments indicated gully erosion dominates the supply of sediment in Knapp Creek and the Upper Bremer River whereas erosion from cultivated soils is the primary sediment source in Blackfellow Creek. Sediment tracing with fallout-radionuclides confirmed subsoil erosion processes dominate the supply of sediment in Knapp Creek and the Upper Bremer River whereas in Blackfellow Creek cultivated and subsoil sources contribute >90% of sediments. Other sediment properties are required to determine the relative sediment contributions of channel bank, gully and cultivated sources in these catchments. The potential of total organic carbon (TOC), total nitrogen (TN), and carbon and nitrogen stable isotopes (δ13C, δ15N) to conservatively discriminate between subsoil sediment sources is presented. The conservativeness of these sediment properties was examined through evaluating particle size variations in depth core soil samples and investigating whether they remain constant in source soils over two sampling occasions. Varying conservative behavior and source discrimination was observed. TN in the

Dike Strength Analysis on a Regional Scale Based On a Stochastic Subsoil Model

NASA Astrophysics Data System (ADS)

Koelewijn, A. R.; Vastenburg, E. W.

2013-12-01

About two-third of the Netherlands is protected against flooding by dikes and levees. The subsoil can be characterized by fluvial and marine sediments. Maintaining the safety of these dikes and levees is of vital importance. Insufficient safety is not permissible, but excessive safety would imply a waste of money and other resources. Therefore safety assessments are carried out on a regular basis. Over the past decades, a practice has grown to calculate a limited number of cross-sections, roughly one every 500 to 1000 meters. For this purpose, a representative cross-section is selected as an estimate of the most vulnerable surface geometry and the subsoil conditions determined from boreholes and cone penetration tests, for which slope stability and piping analyses are carried out. This is a time-consuming procedure which is not only expensive, but also neglects geological knowledge. A method to incorporate geological knowledge of an area, including updating on the basis of additional investigations, has been described in Koelewijn et al. [2011]. In addition, various groups have worked to incorporate geotechnical stability models and detailed Lidar-measurements of the surface into a more efficient and rational calculation process [Knoeff et al. 2011, Lam et al. 2013, van den Ham & Mastbergen, 2013]. Combining this experience with the 3D subsoil model opens possibilities for cost-effective additional soil investigations for those locations where ruling out unfavorable conditions really influences the decisions to be made regarding rejection and improvement, see the figure for examples of different subsoil profiles along a dike. The resulting system has been applied for semi-automated calculations of dikes in various parts of the Netherlands, totalling over 4000 km by now, and a part of the Mississippi levee system. [van den Ham & Mastbergen, 2013] G.A. van den Ham & D.R. Mastbergen, A semi-probabilistic assessment method for flow slides. AGU Fall meeting, 2013 [Knoeff et al. 2011] J.G. Knoeff, E.W. Vastenburg, G.A. van den Ham & J. Lopez de la Cruz, Automated levee flood risk management, 5th Int. Conf. on Flood Management, Tokyo, 2011 [Koelewijn et al. 2011] A.R. Koelewijn, G.A.M. Kruse & J. Pruiksma, Stochastic subsoil modelling - first set-up of the model and reliability analyses, report 12042000-002-HYE-0001, Deltares, Delft, 2011 [In Dutch] [Lam et al. 2013] K.S. Lam, P.W. Gill & L.W.A. Zwang, Implementation of new levee strength modules for continuous safety assessments, Comprehensive Flood Risk Managment, Taylor & Francis, London, 2013, 317-326. Dike sections with stochastic subsoil profiles.

Effect of subsoiling in fallow period on soil water storage and grain protein accumulation of dryland wheat and its regulatory effect by nitrogen application.

PubMed

Sun, Min; Gao, ZhiQiang; Zhao, WeiFeng; Deng, LianFeng; Deng, Yan; Zhao, HongMei; Ren, AiXia; Li, Gang; Yang, ZhenPing

2013-01-01

To provide a new way to increase water storage and retention of dryland wheat, a field study was conducted at Wenxi experimental site of Shanxi Agricultural University. The effect of subsoiling in fallow period on soil water storage, accumulation of proline, and formation of grain protein after anthesis were determined. Our results showed that subsoiling in fallow period could increase water storage in the 0-300 cm soil at pre-sowing stage and at anthesis stage with low or medium N application, especially for the 60-160 cm soil. However, the proline content, glutamine synthetase (GS) activity, glutamate dehydrogenase (GDH) activity in flag leaves and grains were all decreased by subsoiling in fallow period. In addition, the content of albumin, gliadin, and total protein in grains were also decreased while globulin content, Glu/Gli, protein yield, and glutelin content were increased. With N application increasing, water storage of soil layers from 20 to 200 cm was decreased at anthesis stage. High N application resulted in the increment of proline content and GS activity in grains. Besides, correlation analysis showed that soil storage in 40-160 cm soil was negatively correlated with proline content in grains; proline content in grains was positively correlated with GS and GDH activity in flag leaves. Contents of albumin, globulin and total protein in grains were positively correlated with proline content in grains and GDH activity in flag leaves. In conclusion, subsoiling in fallow period, together with N application at 150 kg·hm(-2), was beneficial to increase the protein yield and Glu/Gli in grains which improve the quality of wheat.

The potential application of red mud and soil mixture as additive to the surface layer of a landfill cover system.

PubMed

Ujaczki, Éva; Feigl, Viktória; Molnár, Mónika; Vaszita, Emese; Uzinger, Nikolett; Erdélyi, Attila; Gruiz, Katalin

2016-06-01

Red mud, the by-product of aluminum production, has been regarded as a problematic residue all over the world. Its storage involves risks as evidenced by the Ajka red mud spill, an accident in Hungary where the slurry broke free, flooding the surrounding areas. As an immediate remediation measure more than 5cm thick red mud layer was removed from the flooded soil surface. The removed red mud and soil mixture (RMSM) was transferred into the reservoirs for storage. In this paper the application of RMSM is evaluated in a field study aiming at re-utilizing waste, decreasing cost of waste disposal and providing a value-added product. The purpose was to investigate the applicability of RMSM as surface layer component of landfill cover systems. The field study was carried out in two steps: in lysimeters and in field plots. The RMSM was mixed at ratios ranging between 0 and 50% w/w with low quality subsoil (LQS) originally used as surface layer of an interim landfill cover. The characteristics of the LQS+RMSM mixtures compared to the subsoil (LQS) and the RMSM were determined by physical-chemical, biological and ecotoxicological methods. The addition of RMSM to the subsoil (LQS) at up to 20% did not result any ecotoxic effect, but it increased the water holding capacity. In addition, the microbial substrate utilization became about triple of subsoil (LQS) after 10months. According to our results the RMSM mixed into subsoil (LQS) at 20% w/w dose may be applied as surface layer of landfill cover systems. Copyright © 2016. Published by Elsevier B.V.

Crop response to deep tillage - a meta-analysis

NASA Astrophysics Data System (ADS)

Schneider, Florian; Don, Axel; Hennings, Inga; Schmittmann, Oliver; Seidel, Sabine J.

2017-04-01

Subsoil, i.e. the soil layer below the topsoil, stores tremendous stocks of nutrients and can keep water even under drought conditions. Deep tillage may be a method to enhance the plant-availability of subsoil resources. However, in field trials, deep tillage effects on crop yields were inconsistent. Therefore, we conducted a meta-analysis of crop yield response to subsoiling, deep ploughing and deep mixing of soil profiles. Our search resulted in 1530 yield comparisons following deep and conventional control tillage on 67 experimental cropping sites. The vast majority of the data derived from temperate latitudes, from trials conducted in the USA (679 observations) and Germany (630 observations). On average, crop yield response to deep tillage was slightly positive (6% increase). However, individual deep tillage effects were highly scattered including about 40% yield depressions after deep tillage. Deep tillage on soils with root restrictive layers increased crop yields about 20%, while soils containing >70% silt increased the risk of yield depressions following deep tillage. Generally, deep tillage effects increased with drought intensity indicating deep tillage as climate adaptation measure at certain sites. Our results suggest that deep tillage can facilitate the plant-availability of subsoil nutrients, which increases crop yields if (i) nutrients in the topsoil are growth limiting, and (ii) deep tillage does not come at the cost of impairing topsoil fertility. On sites with root restrictive soil layers, deep tillage can be an effective measure to mitigate drought stress and improve the resilience of crops. However, deep tillage should only be performed on soils with a stable structure, i.e. <70% silt content. We will discuss the contribution of deep tillage options to enhance the sustainability of agricultural production by facilitating the uptake of nutrients and water from the subsoil.

Effect of Subsoiling in Fallow Period on Soil Water Storage and Grain Protein Accumulation of Dryland Wheat and Its Regulatory Effect by Nitrogen Application

PubMed Central

Sun, Min; Gao, ZhiQiang; Zhao, WeiFeng; Deng, LianFeng; Deng, Yan; Zhao, HongMei; Ren, AiXia; Li, Gang; Yang, ZhenPing

2013-01-01

To provide a new way to increase water storage and retention of dryland wheat, a field study was conducted at Wenxi experimental site of Shanxi Agricultural University. The effect of subsoiling in fallow period on soil water storage, accumulation of proline, and formation of grain protein after anthesis were determined. Our results showed that subsoiling in fallow period could increase water storage in the 0–300 cm soil at pre-sowing stage and at anthesis stage with low or medium N application, especially for the 60–160 cm soil. However, the proline content, glutamine synthetase (GS) activity, glutamate dehydrogenase (GDH) activity in flag leaves and grains were all decreased by subsoiling in fallow period. In addition, the content of albumin, gliadin, and total protein in grains were also decreased while globulin content, Glu/Gli, protein yield, and glutelin content were increased. With N application increasing, water storage of soil layers from 20 to 200 cm was decreased at anthesis stage. High N application resulted in the increment of proline content and GS activity in grains. Besides, correlation analysis showed that soil storage in 40–160 cm soil was negatively correlated with proline content in grains; proline content in grains was positively correlated with GS and GDH activity in flag leaves. Contents of albumin, globulin and total protein in grains were positively correlated with proline content in grains and GDH activity in flag leaves. In conclusion, subsoiling in fallow period, together with N application at 150 kg·hm−2, was beneficial to increase the protein yield and Glu/Gli in grains which improve the quality of wheat. PMID:24098371

Black walnut response to subsoiling, irrigation, and vegetation management on a site with a shallow fragipan

Treesearch

F. D. McBride; J. W. Van Sambeek

1995-01-01

Vegetation management with glyphosate and simazine proved to be more effective than preplant subsoiling or irrigation for achieving acceptable walnut biomass growth on an upland old field site (SI = 70 for white oak). In 1980, we direct seeded germinating black walnut seed on an upland, slightly eroded, old field ridge with a 45 to 60 cm deep fragipan. We tested all...

Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

PubMed

Sarabadani, Hamid; Rayhani, Mohammad T

2014-06-01

Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

Identifying the role of historical anthropogenic activities on urban soils: geochemical impact and city scale mapping

NASA Astrophysics Data System (ADS)

Le Guern, Cecile; Baudouin, Vivien; Conil, Pierre

2017-04-01

Recently, European cities have faced several changes including deindustrialization and population increase. To limit urban sprawl, urban densification is preferred. It conducts to (re)develop available areas such as brownfields. Although these areas can be attractive for housing due to their location (in proximity to the city centre or to a riverside), their soils and subsoils are often contaminated. They are therefore potentially harmful for human health and the environment, and potentially costly to remediate. Currently, in case of contamination suspicion, depth geochemical characterization of urban soil and subsoil are carried out at site scale. Nevertheless, large redevelopment project occur at quarter to city scale. It appears therefore useful to acquire the preliminary knowledge on the structure and quality of soil and subsoils, as well as on the potential sources of contamination at quarter to city scale. In the frame of the Ile de Nantes (France) redevelopment project, we considered more particularly anthropogenic deposits and former industrial activities as main sources of contamination linked to human activities. To face the low traceability of the use of anthropogenic deposits and the lack of synthesis of former industrial activities, we carried out a historical study, synthetizing the information spread in numerous archive documents to spatialize the extent of the deposits and of the former activities. In addition we developed a typology of made grounds according to their contamination potential to build a 3D geological model with a geochemical coherence. In this frame, we valorized existing borehole descriptions coming mainly from pollution diagnosis and geotechnical studies. We also developed a methodology to define urban baseline compatibility levels using the existing analytical data at depth from pollution diagnosis. These data were previously gathered in a local geodatabase towards with borehole descriptions (more than 2000 borehole descriptions, more than 1800 analyzed samples, almost 100 000 analyzed parameters). The potential quality of soil and subsoil was spatialized in 2D and 3D on the basis of anthropogenic deposits structure and typology as well as of the potential sources of contamination linked to former industrial activities. Volumes were also calculated to help the developer anticipating the management of excavated materials. Comparison with effective soil and subsoil quality (existing chemical data) shows fairly good anticipation of contamination problems, confirming the interest of spatializing the historical anthropogenic activities to anticipate the quality of urban soil and subsoil and guide city scale mapping. Urban geochemical compatibility levels will be used operationally to enhance the reuse of excavated materials. A better knowledge of soils and subsoils at depth is very useful to optimize urban redevelopment projects, anticipating contamination problems, and managing excavated materials (e.g. local reuse possibilities, disposal costs etc.). The potential economic, environmental and social consequences render it essential for urban sustainable development. 3D geochemical characterization of soil and subsoil for urban (re)development is an ambitious task. Rarely carried out until now, it needs improved development of acquisition, management, visualisation and use of data.

Reformulation of the CBR Procedure. Report 1: Basic Report

DTIC Science & Technology

2012-04-01

originate a superior method of compaction control, the modified density test associated with the name of Ralph R. Proctor . In time, Porter was able to...enough for the subsoil moisture to equalize. Colonel Bragdon in the South Atlantic Division was to choose an airstrip built on sandy clay , a fairly good...subsoil; Colonel Scott in the Southwestern Division, one of lean black clay , a rather poor foundation; Colonel Elliott in the Upper Mississippi

Pasture degradation modifies soil organic matter properties and biochemical functioning in Tibetan grasslands

NASA Astrophysics Data System (ADS)

Spielvogel, Sandra; Steingräber, Laura; Schleuß, Per; Kuzyakov, Yakov; Guggenberger, Georg

2015-04-01

Kobresia pastures of the Tibetan Plateau represent the world's largest alpine ecosystem. Moderate husbandry on Kobresia pastures is beneficial for the storage of soil organic carbon (OC), nitrogen (N) and other nutrients and prevents erosion by establishment of sedge-turf root mats with high OC allocation rates below ground. However, undisturbed root mats are affected by freezing and thawing processes, which cause initial ice cracks. As a consequence decomposition of root mat layers will be accelerated and current sedentarization programs with concomitant increased grazing intensity may additionally enhance root mat degradation. Finally, cracks are enlarged by water and wind erosion as well as pika activities until bare soil surface areas without root mat horizons occur. The aim of this study was to understand the impact of the root mat layer on soil organic carbon stabilization and microbial functioning depending on soil depths and to predict future changes (OC, N and nutrient losses, soil microbial functioning in SOM transformation) by overgrazing and climate change. We investigated the mineral soil below Kobresia root mats along a false time degradation sequence ranging from stage 1 (intact root mat) to stage 4 (mats with large cracks and bare soil patches). Vertical gradients of δ13C values, neutral sugar, cutin and suberin contents as well as microbial biomass estimated by total phospholipid fatty acid (PLFA), microbial community composition (PLFA profiles) and activities of six extracellular enzymes involved in the C, N, and P cycle were assessed. Soil OC and N contents as well as C/N ratios indicate an increasing illuviation of topsoil material into the subsoil with advancing root mat degradation. This was confirmed by more negative δ13C values as well as significantly (p ≤ 0.05) increasing contributions of cutin derived hydroxy fatty acids to OC in the subsoils from degradation stages 1 to 4. PLFA profiles were surprisingly similar in the subsoils of degradation stages 1, 2 and 3 although OC contents and composition in the subsoil changed progressively from stage 1 to 4. Only the PLFA profiles of stage 4 differed from those of the other subsoils, suggesting that microbial communities were mainly controlled by other factors than C and N contents and SOM composition. These findings were also confirmed by the activities of β-glucosidase, xylanase, amino-peptidases and proteases. Those enzyme activities were highest in the subsoil of degradation stage 4, whereas degradation stages 2 and 3 showed low enzyme activities in the subsoil if related to soil OC amount and composition. We conclude that pasture degradation decreases not only mechanical protection of soil surface by Kobresia root mats, but also changes their biochemical and microbial functions.

Constraining the subsoil carbon source to cave-air CO2 and speleothem calcite in central Texas

NASA Astrophysics Data System (ADS)

Bergel, Shelly J.; Carlson, Peter E.; Larson, Toti E.; Wood, Chris T.; Johnson, Kathleen R.; Banner, Jay L.; Breecker, Daniel O.

2017-11-01

Canonical models for speleothem formation and the subsurface carbon cycle invoke soil respiration as the dominant carbon source. However, evidence from some karst regions suggests that belowground CO2 originates from a deeper, older source. We therefore investigated the carbon sources to central Texas caves. Drip-water chemistry of two caves in central Texas implies equilibration with calcite at CO2 concentrations (PCO2_sat) higher than the maximum CO2 concentrations observed in overlying soils. This observation suggests that CO2 is added to waters after they percolate through the soils, which requires a subsoil carbon source. We directly evaluate the carbon isotope composition of the subsoil carbon source using δ13C measurements on cave-air CO2, which we independently demonstrate has little to no contribution from host rock carbon. We do so using the oxidative ratio, OR, defined as the number of moles of O2 consumed per mole of CO2 produced during respiration. However, additional belowground processes that affect O2 and CO2 concentrations, such as gas-water exchange and/or diffusion, may also influence the measured oxidative ratio, yielding an apparent OR (ORapparent). Cave air in Natural Bridge South Cavern has ORapparent values (1.09 ± 0.06) indistinguishable from those expected for respiration alone (1.08 ± 0.06). Pore space gases from soils above the cave have lower values (ORapparent = 0.67 ± 0.05) consistent with respiration and gas transport by diffusion. The simplest explanation for these observations is that cave air in NB South is influenced by respiration in open-system bedrock fractures such that neither diffusion nor exchange with water influence the composition of the cave air. The radiocarbon activities of NB South cave-air CO2 suggest the subsoil carbon source is hundreds of years old. The calculated δ13C values of the subsoil carbon source are consistent with tree-sourced carbon (perhaps decomposing root matter), the δ13C values of which have shifted during industrialization due to changes in the δ13C values and concentrations of atmospheric CO2. Seasonal variations in PCO2_sat in most of the drip waters suggest that these waters exchange with ventilated bedrock fractures in the epikarst, implying that the subsoil CO2 source contributes carbon to speleothems.

Yield Response of Spring Maize to Inter-Row Subsoiling and Soil Water Deficit in Northern China.

PubMed

Liu, Zhandong; Qin, Anzhen; Zhao, Ben; Ata-Ul-Karim, Syed Tahir; Xiao, Junfu; Sun, Jingsheng; Ning, Dongfeng; Liu, Zugui; Nan, Jiqin; Duan, Aiwang

2016-01-01

Long-term tillage has been shown to induce water stress episode during crop growth period due to low water retention capacity. It is unclear whether integrated water conservation tillage systems, such asspringdeepinter-row subsoiling with annual or biennial repetitions, can be developed to alleviate this issue while improve crop productivity. Experimentswere carried out in a spring maize cropping system on Calcaric-fluvicCambisolsatJiaozuoexperimentstation, northern China, in 2009 to 2014. Effects of threesubsoiling depths (i.e., 30 cm, 40 cm, and 50 cm) in combination with annual and biennial repetitionswasdetermined in two single-years (i.e., 2012 and 2014)againstthe conventional tillage. The objectives were to investigateyield response to subsoiling depths and soil water deficit(SWD), and to identify the most effective subsoiling treatment using a systematic assessment. Annualsubsoiling to 50 cm (AS-50) increased soil water storage (SWS, mm) by an average of8% in 0-20 cm soil depth, 19% in 20-80 cm depth, and 10% in 80-120 cm depth, followed by AS-40 and BS-50, whereas AS-30 and BS-30 showed much less effects in increasing SWS across the 0-120 cm soil profile, compared to the CK. AS-50 significantly reduced soil water deficit (SWD, mm) by an average of123% during sowing to jointing, 318% during jointing to filling, and 221% during filling to maturity, compared to the CK, followed by AS-40 and BS-50. An integrated effect on increasing SWS and reducing SWD helped AS-50 boost grain yield by an average of 31% and biomass yield by 30%, compared to the CK. A power function for subsoiling depth and a negative linear function for SWD were used to fit the measured yields, showing the deepest subsoiling depth (50 cm) with the lowest SWD contributed to the highest yield. Systematic assessment showed that AS-50 received the highest evaluation index (0.69 out of 1.0) among all treatments. Deepinter-row subsoilingwith annual repetition significantly boosts yield by alleviating SWD in critical growth period and increasing SWS in 20-80 cm soil depth. The results allow us to conclude that AS-50 can be adopted as an effective approach to increase crop productivity, alleviate water stress, and improve soil water availability for spring maize in northern China.

Soil Respiration Controls Ionic Nutrient Concentration In Percolating Water In Rice Fields

NASA Astrophysics Data System (ADS)

Kimura, M.

2004-12-01

Soil water in the plow layer in rice fields contains various kinds of cations and anions, and they are lost from the plow layer by water percolation. Some portions of CO2 produced by respirations of rice roots and soil microorganisms are also leached by water percolation to the subsoil layer as HCO3-. As the electrical neutrality of inorganic substances in percolating water is maintained when they are assumed to be in the form of simple cations and anions, soil respiration accelerates the leaching of ionic nutrients from the plow layer by water percolation. The proportion of inorganic carbon (Σ CO2) originated from photosynthates in the total Σ CO2 in soil solution in the plow layer was from 28 to 36 % in the rice straw amended soil and from 16 to 31 % in the soil without rice straw amendment in a soil pot experiment with rice plant after the maximum tillering stage. Most of Σ CO2 in percolating water from the plow layer accumulates in the subsoil layer. Periodical measurement of Σ CO2 in percolating water at 13 and 40 cm soil depths indicated that 10 % of total soil organic C in the plow layer was leached down from the plow layer (13 cm), and that about 90 % of it was retained in the subsoil layer to the depth of 40 cm. Water soluble organic materials are also leached from the plow layer by water percolation, and the leaching is accelerated by soil reduction. Soil reduction decreased the content of organic materials that were bound with ferric iron in soil (extractable by 0.1M Na4P2O7 + NaBH4) and increased the content of organic materials that were extractable by the neutral chelating solution (0.1M Na4P2O7). In addition, water percolation transformed the latter organic materials to those that were extractable by water and a neutral salt. Considerable portions of organic materials in percolating water are adsorbed in the subsoil layer, and then partially decomposed and polymerized to specific soil organic materials in the subsoil. Organic materials that were leached from the plow layer by percolating water amounted to 170 kgC ha-1 in a Japanese rice field, among which 120 kgC of organic materials were adsorbed in the subsoil layer between 13 and 40 cm depth.

Change in Stiffness of Pavement Layers in the Linear Discontinuous Deformation Area

NASA Astrophysics Data System (ADS)

Grygierek, Marcin

2017-10-01

The underground mining exploitation causes deformations on the surface of the area which are classified as continuous or discontinuous. Mining deformations cause loosening or compression of the subsoil. Loosening has an impact on the reduction of the subsoil stiffness. As a result the reduction of subsoil stiffness causes loosening of construction layers built in that subsoil. Pavement is a specific case. If there happens to be loosening then the fatigue life of pavement is reduced and premature damages can be observed such as fatigue cracks or/and structural deformation. Discontinuous deformations are an especially interesting case. They not only cause the reduction of the stiffness of the subsoil and pavement layers but also cause rapid deterioration in roughness. Change of roughness is very dangerous especially on fast roads such as a highway. Lately there can be observed the so called linear discontinuous surface deformations in the lanes in the mining area. Unfortunately, the ‘in situ’ research, presenting experiments on the effect of linear discontinuous deformations on the pavement, is in short supply. It is especially crucial with regard to the design of pavement reinforcement and the specification of optimal length of the reinforced part of the road. The article presents the results of ‘in situ’ tests carried out on the chosen pavements where the so called linear discontinuous surface deformation has appeared. The genesis of the damage is connected with the underground mining exploitation. Falling Weight Deflectometer (FWD) has been used in researches. Measuring points were carried out with high frequency which helped to acquire a very interesting distribution of deflections. The distribution of deflections well shows the impact of linear discontinuous deformation on the changes in stiffness pavement layers. In the analysis of data from FWD there has been used back calculation which worked modulus of layers out. The results of researches and analysis have allowed to specify the scale of stiffness reduction of subsoil and pavement layers and, above all, to specify a minimal area of reinforcement. Therefore, the results of the analysis can be very helpful in determining the range of reinforcement as well as designing reinforcement. Of course, researches should be continued for better knowledge about the impact of discontinuous deformations on pavement.

The carbon count of 2000 years of rice cultivation.

PubMed

Kalbitz, Karsten; Kaiser, Klaus; Fiedler, Sabine; Kölbl, Angelika; Amelung, Wulf; Bräuer, Tino; Cao, Zhihong; Don, Axel; Grootes, Piet; Jahn, Reinhold; Schwark, Lorenz; Vogelsang, Vanessa; Wissing, Livia; Kögel-Knabner, Ingrid

2013-04-01

More than 50% of the world's population feeds on rice. Soils used for rice production are mostly managed under submerged conditions (paddy soils). This management, which favors carbon sequestration, potentially decouples surface from subsurface carbon cycling. The objective of this study was to elucidate the long-term rates of carbon accrual in surface and subsurface soil horizons relative to those of soils under nonpaddy management. We assessed changes in total soil organic as well as of inorganic carbon stocks along a 2000-year chronosequence of soils under paddy and adjacent nonpaddy management in the Yangtze delta, China. The initial organic carbon accumulation phase lasts much longer and is more intensive than previously assumed, e.g., by the Intergovernmental Panel on Climate Change (IPCC). Paddy topsoils accumulated 170-178 kg organic carbon ha(-1) a(-1) in the first 300 years; subsoils lost 29-84 kg organic carbon ha(-1) a(-1) during this period of time. Subsoil carbon losses were largest during the first 50 years after land embankment and again large beyond 700 years of cultivation, due to inorganic carbonate weathering and the lack of organic carbon replenishment. Carbon losses in subsoils may therefore offset soil carbon gains or losses in the surface soils. We strongly recommend including subsoils into global carbon accounting schemes, particularly for paddy fields. © 2012 Blackwell Publishing Ltd.

Post-mining deterioration of bauxite overburdens in Jamaica: storage methods or subsoil dilution?

NASA Astrophysics Data System (ADS)

Harris, Mark A.; Omoregie, Samson N.

2008-03-01

Rapid degradation of disturbed soil from a karst bauxite mine in Jamaica was recorded. Substantial macronutrient losses were incurred during a short (1 month) or a long (12 months) storage of the replaced topsoils during frequent wet/dry changes. The results suggested very high rates (>70% in the first year) of soil degradation from storage, alongside moderate rates (30%) within the same storage dump. However, higher levels of soil organic matter (SOM) were indicated just below the surface, compared with the surface horizons. It was unlikely that under a high leaching humid tropical rainfall regime, natural degradation processes could have re-emplaced such material firmly intact in the 15-30 cm zone. It was therefore concluded that these SOM anomalies were due to mechanical dilution of surface soil with subsoil material during overburden removal and emplacement rather than from long storage. Increasing the soil organic content during storage could be one corrective approach. However, it is far less costly to exercise greater care to apply more precise overburden removal and emplacement techniques initially, than it is to correct the results of topsoil contamination with subsoil. Although this study was limited to one mine, in the context of imminent large-scale mining expansion and current practices, further investigations are needed to accurately ascertain the proportion of similar subsoil contamination in other bauxite-mined sites.

Analysis of Causes of Uplift Anomalies in the Čierny Váh Subsoil

NASA Astrophysics Data System (ADS)

Bednárová, Emília; Grambličková, Danka; Škvarka, Juraj; Majerčák, Vlastimil; Slávik, Ivan

2017-12-01

The pumped storage hydropower plant of Čierny Váh was created by means of damming up the valley of the Čierny Váh River. The dam is 18.5 m high above terrain and 375 m long in the dam’s crest. Total capacity of the reservoir is 5.1 million m3. Complicated geological conditions in the subsoil of dam’s body - fractured dolomite with local occurrence of tectonic breccia and clays, with the occurrence of intense disturbances - called for the construction of the grouting curtain in the dam’s subsoil. Its depth is about 20 in the area of the riverine plain, and about 60 m in the areas of abutments. During foregoing operations of the structure, more than 30 years, local anomalies in the uplift development in the right abutment’s subsoil of the lower reservoir dam were recorded. Their abnormally high values on the downstream side of grouting curtain have become the subject of extensive discussion and a stimulus for its remediation. To ensure reliable operation of the hydraulic structure a comprehensive analysis of the impact of the long-term operation of the reservoir on the dam safety was carried out. This included an examination of the causes of anomalous development of uplifts using FEM numerical modelling. The paper presents obtained results from this analysis.

Input of easily available organic C and N stimulates microbial decomposition of soil organic matter in arctic permafrost soil

PubMed Central

Wild, Birgit; Schnecker, Jörg; Alves, Ricardo J. Eloy; Barsukov, Pavel; Bárta, Jiří; Čapek, Petr; Gentsch, Norman; Gittel, Antje; Guggenberger, Georg; Lashchinskiy, Nikolay; Mikutta, Robert; Rusalimova, Olga; Šantrůčková, Hana; Shibistova, Olga; Urich, Tim; Watzka, Margarete; Zrazhevskaya, Galina; Richter, Andreas

2014-01-01

Rising temperatures in the Arctic can affect soil organic matter (SOM) decomposition directly and indirectly, by increasing plant primary production and thus the allocation of plant-derived organic compounds into the soil. Such compounds, for example root exudates or decaying fine roots, are easily available for microorganisms, and can alter the decomposition of older SOM (“priming effect”). We here report on a SOM priming experiment in the active layer of a permafrost soil from the central Siberian Arctic, comparing responses of organic topsoil, mineral subsoil, and cryoturbated subsoil material (i.e., poorly decomposed topsoil material subducted into the subsoil by freeze–thaw processes) to additions of 13C-labeled glucose, cellulose, a mixture of amino acids, and protein (added at levels corresponding to approximately 1% of soil organic carbon). SOM decomposition in the topsoil was barely affected by higher availability of organic compounds, whereas SOM decomposition in both subsoil horizons responded strongly. In the mineral subsoil, SOM decomposition increased by a factor of two to three after any substrate addition (glucose, cellulose, amino acids, protein), suggesting that the microbial decomposer community was limited in energy to break down more complex components of SOM. In the cryoturbated horizon, SOM decomposition increased by a factor of two after addition of amino acids or protein, but was not significantly affected by glucose or cellulose, indicating nitrogen rather than energy limitation. Since the stimulation of SOM decomposition in cryoturbated material was not connected to microbial growth or to a change in microbial community composition, the additional nitrogen was likely invested in the production of extracellular enzymes required for SOM decomposition. Our findings provide a first mechanistic understanding of priming in permafrost soils and suggest that an increase in the availability of organic carbon or nitrogen, e.g., by increased plant productivity, can change the decomposition of SOM stored in deeper layers of permafrost soils, with possible repercussions on the global climate. PMID:25089062

Efficacies of designer biochars in improving biomass and nutrient uptake of winter wheat grown in a hard setting subsoil layer.

PubMed

Sigua, G C; Novak, J M; Watts, D W; Johnson, M G; Spokas, K

2016-01-01

In the Coastal Plains region of the United States, the hard setting subsoil layer of Norfolk soils results in low water holding capacity and nutrient retention, which often limits root development. In this region, the Norfolk soils are under intensive crop production that further depletes nutrients and reduces organic carbon (C). Incorporation of pyrolyzed organic residues or "biochars" can provide an alternative recalcitrant C source. However, biochar quality and effect can be inconsistent and different biochars react differently in soils. We hypothesized that addition of different designer biochars will have variable effects on biomass and nutrient uptake of winter wheat. The objective of this study was to investigate the effects of designer biochars on biomass productivity and nutrient uptake of winter wheat (Triticum aestivum L.) in a Norfolk's hard setting subsoil layer. Biochars were added to Norfolk's hard setting subsoil layer at the rate of 40 Mg ha(-1). The different sources of biochars were: plant-based (pine chips, PC); animal-based (poultry litter, PL); 50:50 blend (50% PC:50% PL); 80:20 blend (80% PC:20% PL); and hardwood (HW). Aboveground and belowground biomass and nutrient uptake of winter wheat varied significantly (p⩽0.0001) with the different designer biochar applications. The greatest increase in the belowground biomass of winter wheat over the control was from 80:20 blend of PC:PL (81%) followed by HW (76%), PC (59%) and 50:50 blend of PC:PL (9%). However, application of PL resulted in significant reduction of belowground biomass by about 82% when compared to the control plants. The average uptake of P, K, Ca, Mg, Na, Al, Fe, Cu and Zn in both the aboveground and belowground biomass of winter wheat varied remarkably with biochar treatments. Overall, our results showed promising significance for the treatment of a Norfolk's hard setting subsoil layer since designer biochars did improve both aboveground/belowground biomass and nutrient uptake of winter wheat. Published by Elsevier Ltd.

Extended sorption partitioning models for pesticide leaching risk assessments: Can we improve upon the koc concept?

PubMed

Jarvis, Nicholas

2016-01-01

Models used to assess leaching of pesticides to groundwater still rely on the sorption koc value, even though its limitations have been known for several decades, especially for soils of low organic carbon content (i.e. subsoils). This is mainly because the general applicability of any improved model approach that is also simple enough to use for regulatory purposes has not been demonstrated. The objective of this study was to test and compare alternative models of sorption that could be useful in pesticide risk assessment and management. To this end, a database containing the results of batch sorption experiments for pesticides was compiled from published studies in the literature, which placed at least as much emphasis on measurements in subsoil horizons as in topsoil. The database includes 785 data entries from 34 different published studies and for 21 different active substances. Overall, the apparent koc value, koc(app), roughly doubled as the soil organic carbon content decreased by a factor of ten. Nevertheless, in nearly half of the individual datasets, a constant koc value proved to be an adequate model. Further analysis showed that significant increases in koc(app) in subsoil were found primarily for the more weakly adsorbing compounds (koc values

Surficial gains and subsoil losses of soil carbon and nitrogen during secondary forest development.

PubMed

Mobley, Megan L; Lajtha, Kate; Kramer, Marc G; Bacon, Allan R; Heine, Paul R; Richter, Daniel Deb

2015-02-01

Reforestation of formerly cultivated land is widely understood to accumulate above- and belowground detrital organic matter pools, including soil organic matter. However, during 40 years of study of reforestation in the subtropical southeastern USA, repeated observations of above- and belowground carbon documented that significant gains in soil organic matter (SOM) in surface soils (0-7.5 cm) were offset by significant SOM losses in subsoils (35-60 cm). Here, we extended the observation period in this long-term experiment by an additional decade, and used soil fractionation and stable isotopes and radioisotopes to explore changes in soil organic carbon and soil nitrogen that accompanied nearly 50 years of loblolly pine secondary forest development. We observed that accumulations of mineral soil C and N from 0 to 7.5 cm were almost entirely due to accumulations of light-fraction SOM. Meanwhile, losses of soil C and N from mineral soils at 35 to 60 cm were from SOM associated with silt and clay-sized particles. Isotopic signatures showed relatively large accumulations of forest-derived carbon in surface soils, and little to no accumulation of forest-derived carbon in subsoils. We argue that the land use change from old field to secondary forest drove biogeochemical and hydrological changes throughout the soil profile that enhanced microbial activity and SOM decomposition in subsoils. However, when the pine stands aged and began to transition to mixed pines and hardwoods, demands on soil organic matter for nutrients to support aboveground growth eased due to pine mortality, and subsoil organic matter levels stabilized. This study emphasizes the importance of long-term experiments and deep measurements when characterizing soil C and N responses to land use change and the remarkable paucity of such long-term soil data deeper than 30 cm. © 2014 John Wiley & Sons Ltd.

Retention and loss of water extractable carbon in soils: effect of clay properties.

PubMed

Nguyen, Trung-Ta; Marschner, Petra

2014-02-01

Clay sorption is important for organic carbon (C) sequestration in soils, but little is known about the effect of different clay properties on organic C sorption and release. To investigate the effect of clay content and properties on sorption, desorption and loss of water extractable organic C (WEOC), two experiments were conducted. In experiment 1, a loamy sand alone (native) or mixed with clay isolated from a surface or subsoil (78 and 96% clay) resulting in 90, 158 and 175 g clay kg(-1) soil. These soil treatments were leached with different WEOC concentrations, and then CO2 release was measured for 28 days followed by leaching with reverse osmosis water at the end of experiment. The second experiment was conducted to determine WEOC sorption and desorption of clays isolated from the loamy sand (native), surface soil and subsoil. Addition of clays isolated from surface and subsoil to sandy loam increased WEOC sorption and reduced C leaching and cumulative respiration in percentage of total organic C and WEOC added when expressed per g soil and per g clay. Compared to clays isolated from the surface and subsoil, the native clay had higher concentrations of illite and exchangeable Ca(2+), total organic C and a higher CEC but a lower extractable Fe/Al concentration. This indicates that compared to the clay isolated from the surface and the subsoil, the native clay had fewer potential WEOC binding sites because it had lower Fe/Al content thus lower number of binding sites and the existing binding sites are already occupied native organic matter. The results of this study suggest that in the soils used here, the impact of clay on WEOC sorption and loss is dependent on its indigenous organic carbon and Fe and/or Al concentrations whereas clay mineralogy, CEC, exchangeable Ca(2+) and surface area are less important. © 2013.

Steering mechanism for a subsoil boring apparatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinnan, F.R.

This paper describes a subsoil boring apparatus. It comprises: a rotatable, steerable boring assembly; motor means for producing rotary motion; pipe string means coupled to the motor means and the boring assembly to import rotation thereto; and impacting means coupled to the motor means to apply impact forces to the pipe string means to improve the steerability of the boring assembly wherein only on of the motor means and the impact means can be applied to the k pipe string means at one time.

Electron beam injected into ground generates subsoil x-rays that may deactivate concealed electronics used to trigger explosive devices

NASA Astrophysics Data System (ADS)

Retsky, Michael

2008-04-01

Explosively formed projectiles (EFP) are a major problem in terrorism and asymmetrical warfare. EFPs are often triggered by ordinary infrared motion detectors. A potential weak link is that such electronics are not hardened to ionizing radiation and can latch-up or enter other inoperative states after exposure to a single short event of ionizing radiation. While these can often be repaired with a power restart, they also can produce shorts and permanent damage. A problem of course is that we do not want to add radiation exposure to the long list of war related hazards. Biological systems are highly sensitive to integrated dosage but show no particular sensitivity to short pulses. There may be a way to generate short pulsed subsoil radiation to deactivate concealed electronics without introducing radiation hazards to military personnel and civilian bystanders. Electron beams of 30 MeV that can be produced by portable linear accelerators (linacs) propagate >20 m in air and 10-12 cm in soil. X-radiation is produced by bremsstrahlung and occurs subsoil beneath the point of impact and is mostly forward directed. Linacs 1.5 m long can produce 66 MWatt pulses of subsoil x-radiation 1 microsecond or less in duration. Untested as yet, such a device could be mounted on a robotic vehicle that precedes a military convoy and deactivates any concealed electronics within 10-20 meters on either side of the road.

Elevated [CO2] mitigates the effect of surface drought by stimulating root growth to access sub-soil water.

PubMed

Uddin, Shihab; Löw, Markus; Parvin, Shahnaj; Fitzgerald, Glenn J; Tausz-Posch, Sabine; Armstrong, Roger; O'Leary, Garry; Tausz, Michael

2018-01-01

Through stimulation of root growth, increasing atmospheric CO2 concentration ([CO2]) may facilitate access of crops to sub-soil water, which could potentially prolong physiological activity in dryland environments, particularly because crops are more water use efficient under elevated [CO2] (e[CO2]). This study investigated the effect of drought in shallow soil versus sub-soil on agronomic and physiological responses of wheat to e[CO2] in a glasshouse experiment. Wheat (Triticum aestivum L. cv. Yitpi) was grown in split-columns with the top (0-30 cm) and bottom (31-60 cm; 'sub-soil') soil layer hydraulically separated by a wax-coated, root-penetrable layer under ambient [CO2] (a[CO2], ∼400 μmol mol-1) or e[CO2] (∼700 μmol mol-1) [CO2]. Drought was imposed from stem-elongation in either the top or bottom soil layer or both by withholding 33% of the irrigation, resulting in four water treatments (WW, WD, DW, DD; D = drought, W = well-watered, letters denote water treatment in top and bottom soil layer, respectively). Leaf gas exchange was measured weekly from stem-elongation until anthesis. Above-and belowground biomass, grain yield and yield components were evaluated at three developmental stages (stem-elongation, anthesis and maturity). Compared with a[CO2], net assimilation rate was higher and stomatal conductance was lower under e[CO2], resulting in greater intrinsic water use efficiency. Elevated [CO2] stimulated both above- and belowground biomass as well as grain yield, however, this stimulation was greater under well-watered (WW) than drought (DD) throughout the whole soil profile. Imposition of drought in either or both soil layers decreased aboveground biomass and grain yield under both [CO2] compared to the well-watered treatment. However, the greatest 'CO2 fertilisation effect' was observed when drought was imposed in the top soil layer only (DW), and this was associated with e[CO2]-stimulation of root growth especially in the well-watered bottom layer. We suggest that stimulation of belowground biomass under e[CO2] will allow better access to sub-soil water during grain filling period, when additional water is converted into additional yield with high efficiency in Mediterranean-type dryland agro-ecosystems. If sufficient water is available in the sub-soil, e[CO2] may help mitigating the effect of drying surface soil.

Hydrothermal activity and subsoil complexity: implication for degassing processes at Solfatara crater, Campi Flegrei caldera

NASA Astrophysics Data System (ADS)

Montanaro, Cristian; Mayer, Klaus; Isaia, Roberto; Gresse, Marceau; Scheu, Bettina; Yilmaz, Tim I.; Vandemeulebrouck, Jean; Ricci, Tullio; Dingwell, Donald B.

2017-12-01

The Solfatara area and its fumaroles are the main surface expression of the vigorous hydrothermal activity within the active Campi Flegrei caldera system. At depth, a range of volcanic and structural processes dictate the actual state of the hydrothermal system below the crater. The presence of a large variety of volcanic products at shallow depth (including pyroclastic fallout ash beds, pyroclastic density current deposits, breccias, and lavas), and the existence of a maar-related fault system appears to exert major controls on the degassing and alteration behavior. Adding further to the complexity of this environment, variations in permeability and porosity, due to subsoil lithology and alteration effects, may further influence fluid flow towards the surface. Here, we report results from a field campaign conducted in July 2015 that was designed to characterize the in situ physical (temperature, humidity) and mechanical (permeability, strength, stiffness) properties of the Solfatara crater subsoil. The survey also included a mapping of the surficial hydrothermal features and their distributions. Finally, laboratory measurements (porosity, granulometry) of selected samples were performed. Our results enable the discrimination of four main subsoils around the crater: (1) the Fangaia domain located in a topographic low in the southwestern sector, (2) the silica flat domain on the western altered side, (3) the new crust domain in the central area, and (4) the crusted hummocks domain that dominates the north, east, and south parts. These domains are surrounded by encrusted areas, reworked material, and vegetated soil. The distribution of these heterogeneous subsoils suggests that their formation is mostly related to (i) the presence of the Fangaia domain within the crater and (ii) a system of ring faults bordering it. The subsoils show an alternation between very high and very low permeabilities, a fact which seems to affect both the temperature distribution and surficial degassing. A large range of surface temperatures (from 25 up to 95 °C) has been measured across these surfaces, with the hottest spot corresponding to the mud pools, the area of new crust formation, and the crusted hummocks. In the subsoil, the distribution of temperature is more complex and controlled by the presence of coarser, and more permeable, sandy/pebbly levels. These act as preferential pathways for hot hydrothermal fluid circulation. In contrast, low permeability, fine-grained levels act as thermal insulators that remain relatively cold and hinder fluid escape to the surface. Hot gases reach the surface predominantly along (vertical) fractures. When this occurs, mound-like structures can be formed by a cracking and healing process associated with significant degassing. It is anticipated that the results presented here may contribute to an improved understanding of the hazard potential associated with the ongoing hydrothermal activity within the Solfatara crater. At this site the permeability of the near-surface environment and its changes in space and time can affect the spatial and temporal distribution of gas and heat emission. Particularly, in areas where reduction in permeability occurs, it can produce pore pressure augmentation that may result in explosive events.

Microbial community changes as a possible factor controlling carbon sequestration in subsoil

NASA Astrophysics Data System (ADS)

Strücker, Juliane; Jörgensen, Rainer Georg

2015-04-01

In order to gain more knowledge regarding the microbial community and their influence on carbon sequestration in subsoil two depth profiles with different soil organic carbon (SOC) concentrations were sampled. The SOC concentrations developed naturally due to deposition and erosion. This experiment offers the opportunity to investigate to which extend natural SOC availability or other subsoil specific conditions influence the composition and the functional diversity of the microbial community and in return if there is any evidence how the microbial community composition affects carbon sequestration under these conditions. Soil samples were taken at four different depths on two neighbouring arable sites; one Kolluvisol with high SOC concentrations (8-12 g/kg) throughout the profile and one Luvisol with low SOC concentrations (3-4 g/kg) below 30 cm depth. The multi substrate induced respiration (MSIR) method was used to identify shifts in the functional diversity of the microbial community along the depth profiles. Amino sugars Muramic Acid and Glucosamine were measured as indicators for bacterial and fungal residues and ergosterol was determined as marker for saprotrophic fungi. The results of the discriminant analysis of the respiration values obtained from the 17 substrates used in the MSIR show that the substrate use in subsoil is different from the substrate use in topsoil. The amino sugar analysis and the ratio of ergosterol to microbial biomass C indicate that the fungal dominance of the microbial community decreases with depth. The results from this study support previous findings, which also observed decreasing fungal dominance with depth. Furthermore the MSIR approach shows clearly that not only the composition of the microbial community but also their substrate use changes with depth. Thus, a different microbial community with altered substrate requirements could be an important reason for enhanced carbon sequestration in subsoil. The fact that the MSIR was also able to differentiate between the two sites proves the assumption that resources are an important factor controlling the functional diversity of the microbial community, as abiotic factors are very similar for the two profiles, but the sites show a different depth gradient for SOC.

Lysimeter Study of Plant Water Uptake in a Model Forest Ecosystem on Heavy Metal Contaminated Soil

NASA Astrophysics Data System (ADS)

Menon, M.; Abbaspour, K.; Schulin, R.; Oswald, S.

2003-04-01

We have been investigating the impact of heavy metal stress on the water regime of young forest ecosystems grown in 32 open top lysimeters (3 m in diameter and 1 m deep). The factorial treatments of the lysimeters include variations of rainwater acidity (acidic, ambient rain), subsoil type (acidic, calcareous), and soil contamination (with and without copper, zinc and cadmium in the top 20 cm). Each lysimeter was planted in spring of 2000 with the same selection of trees and herbaceous plants. All lysimeters are equipped with tensiometers for monitoring of pressure head and time domain reflectometry for measuring of water content. Irrigation was applied equally to all lysimeters through sprinkler devices. Drainage water was collected by means of canisters installed at the bottom of the lysimeters, and thus evapotranspiration could be calculated through water balancing. We monitored the water regime for two years including an imposed drought period. Significantly more water was extracted from the calcareous than the acidic subsoil. The water potential measurements show that also the heavy metal polluted topsoil had a significant influence on the water regime. Metal stress was particularly evident under reduced irrigation. We suspect that the roots were damaged in the contaminated topsoil. In contrast to the subsoil type, heavy metal pollution did not produce a significant effect on evapotranspiration (ET) though, and neither did acidic rain. Pot experiments confirmed that in presence of clean subsoil plants compensated for metal stress in contaminated topsoil by shifting their root activity from contaminated to uncontaminated zones.

Biochars impact on water infiltration and water quality through a compacted subsoil layer.

PubMed

Novak, Jeff; Sigua, Gilbert; Watts, Don; Cantrell, Keri; Shumaker, Paul; Szogi, Ariel; Johnson, Mark G; Spokas, Kurt

2016-01-01

Soils in the SE USA Coastal Plain region frequently have a compacted subsoil layer (E horizon), which is a barrier for water infiltration. Four different biochars were evaluated to increase water infiltration through a compacted horizon from a Norfolk soil (fine-loamy, kaolinitic, thermic, Typic Kandiudult). In addition, we also evaluated biochars effect on water quality. Biochars were produced by pyrolysis at 500 °C from pine chips (Pinus taeda), poultry litter (Gallus domesticus) feedstocks, and as blends (50:50 and 80:20) of pine chip:poultry litter. Prior to pyrolysis, the feedstocks were pelletized and sieved to >2-mm pellets. Each biochar was mixed with the subsoil at 20 g/kg (w/w) and the mixture was placed in columns. The columns were leached four times with Milli-Q water over 128 d of incubation. Except for the biochar produced from poultry litter, all other applied biochars resulted in significant water infiltration increases (0.157-0.219 mL min(-1); p<0.05) compared to the control (0.095 mL min(-1)). However, water infiltration in each treatment were influenced by additional water leaching. Leachates were enriched in PO4, SO4, Cl, Na, and K after addition of poultry litter biochar, however, their concentrations declined in pine chip blended biochar treatments and after multiple leaching. Adding biochars (except 100% poultry litter biochar) to a compacted subsoil layer can initially improve water infiltration, but, additional leaching revealed that the effect remained only for the 50:50 pine chip:poultry litter blended biochar while it declined in other biochar treatments. Published by Elsevier Ltd.

Sorption-desorption behavior of PCP on soil organic matter and clay minerals.

PubMed

Pu, Xunchi; Cutright, Teresa J

2006-08-01

Pentachlorophenol (PCP) contamination is a severe environmental problem due to its widespread occurrence, toxicity and recalcitrance. In order to gain a better understanding of the fate of PCP in soils, the role of the soil organic matter (SOM) and clay minerals in the PCP sorption-desorption was studied on two bulk field soils, two subsoils (i.e., SOM or clay-removed soil) and two artificial soils. The two field soils used were a silty loam from New Mexico (NM) containing 10% clay and a sandy-clay-loam from Colombia (CO) South America comprised of 18% clay minerals. The bulk CO soil containing kaolinite sorbed significantly less PCP than the NM soil. All soils depicted an apparent hysteresis during sorption. The CO bulk and subsoils desorbed 14-20% and 15-26% of the sorbed PCP respectively whereas the NM bulk and subsoils desorbed only 4-12% and 5-16%, respectively. Experiments conducted with pure clay and artificial soils indicated that the expandable clay minerals were key sorbent material. Additional studies to investigate the interaction between SOM and clay minerals are needed to fully understand sorptive phenomena.

A Comparative Study on Safe Pile Capacity as Shown in Table 1 of IS 2911 (Part III): 1980

NASA Astrophysics Data System (ADS)

Pakrashi, Somdev

2017-06-01

Code of practice for design and construction of under reamed pile foundations: IS 2911 (Part-III)—1980 presents one table in respect of safe load for bored cast in situ under reamed piles in sandy and clayey soils including black cotton soils, stem dia. of pile ranging from 20 to 50 cm and its effective length being 3.50 m. A comparative study, was taken up by working out safe pile capacity for one 400 dia., 3.5 m long bored cast in situ under reamed pile based on subsoil properties obtained from soil investigation work as well as subsoil properties of different magnitudes of clayey, sandy soils and comparing the same with the safe pile capacity shown in Table 1 of that IS Code. The study reveals that safe pile capacity computed from subsoil properties, barring a very few cases, considerably differs from that shown in the aforesaid code and looks forward for more research work and study to find out a conclusive explanation of this probable anomaly.

Biological subsoil management: new insights into processes of structure building and implications for crop growth

NASA Astrophysics Data System (ADS)

Athmann, Miriam; Kautz, Timo; Köpke, Ulrich

2017-04-01

Large sized continuous biopores (diameter > 2 mm) in arable subsoils can contribute to enhance soil aeration, increase water infiltration, reduce water runoff and serve as preferential pathways for root growth. Biopores can be generated by taproots, but these pores probably have limited physical stability unless they are colonized by anecic earthworms and coated with worm cast. Long-term field experiments have shown that populations of anecic earthworms and numbers of biopores are promoted by perennial fodder cropping, no-till cropping and reduced tillage systems, i.e. extended soil rest. Potential effects of biopores on root growth of annual crops include accelerating access to deep soil layers, facilitating exploitation of water while simultaneously allowing nutrient acquisition from the pore wall and the bulk soil. Biopores can be considered as hot spots for nutrient acquisition of crops, especially when the pore wall is enriched in nutrients as a consequence of deposition of decaying plant material and feces of earthworms. However, the extent of such effects largely depends on physical properties of the bulk soil. Preferential root growth through biopores has been observed in many types of subsoil. The role of biopores is expected to be relevant especially when rooting in the bulk soil is impeded by high penetration resistance. Nevertheless, in hard-setting clay soils clumping of roots has been reported, when roots were unable to re-enter the bulk soil from biopores' lumen. Recent field experiments on a deep loamy Haplic Luvisol indicated increased biopore density in the subsoil promoting root growth of winter cereals and winter oilseed rape not necessarily resulting in significant effects on shoot parameters. Nevertheless, in a dry year increased biopore density had beneficial effects on N uptake, root and shoot growth and grain yield of spring crops.

Citrus stand ages regulate the fraction alteration of soil organic carbon under a citrus/Stropharua rugodo-annulata intercropping system in the Three Gorges Reservoir area, China.

PubMed

Zhang, Yang; Ni, Jiupai; Yang, John; Zhang, Tong; Xie, Deti

2017-08-01

Soil carbon fractionation is a valuable indicator in assessing stabilization of soil organic matter and soil quality. However, limited studies have addressed how different vegetation stand ages under intercropping agroforestry systems, could affect organic carbon (OC) accumulation in bulk soil and its physical fractions. A field study thus investigated the impact of citrus plantation age (15-, 25-, and 45-year citrus) on the bulk soil organic carbon (SOC) and SOC fractions and yields of Stropharia rugoso-annulata (SRA) in the Three Gorges Reservoir area, Chongqing, China. Results indicated that the intercropping practice of SRA with citrus significantly increased the SOC by 57.4-61.6% in topsoil (0-10 cm) and by 24.8-39.9% in subsoil (10-30 cm). With a significantly higher enhancement under the 25-year citrus stand than the other two stands, all these citrus stands of three ages also resulted in a significant increase of free particulate OC (fPOC, 60.1-62.4% in topsoil and 34.8-46.7% in subsoil), intra-micro aggregate particulate OC (iPOC, 167.6-206.0% in topsoil and 2.77-61.09% in subsoil), and mineral-associated OC (MOC, 43.6-46.5% in topsoil and 26.0-51.5% in subsoil). However, there were no significant differences in yields of SRA under three citrus stands. Our results demonstrated that citrus stand ages did play an important role in soil carbon sequestration and fractionation under a citrus/SRA intercropping system, which could therefore provide a sustainable agroforestry system to enhance concurrently the SOC accumulation while mitigating farmland CO 2 emission.

Sorption and degradation of chlorophenols, nitrophenols and organophosphorus pesticides in the subsoil under landfills — laboratory studies

NASA Astrophysics Data System (ADS)

Kjeldsen, Peter; Kjølholt, Jesper; Schultz, Birgit; Christensen, Thomas H.; Tjell, Jens Christian

1990-09-01

Landfills and old industrial plant sites have been identified in an increasing number of cases as point sources of groundwater pollution, dissipating a wide range of industrial chemicals and pesticides. To study the fate of co-disposed chemicals in the subsoil of landfills, anaerobic soil columns loaded with anaerobic leachate from a municipal landfill were set up. The leachate was spiked with eleven compounds representing three groups of chemicals: chlorophenols, nitrophenols and organophosphates. Two subsoils were used in the study. The columns were maintained at Danish groundwater temperature (8-10°C), and were run for a period of 10 months. Analysis of the influent leachate concentrations of the spiked compounds showed that the concentrations were constant during the entire experimental period. Many of the compounds showed delayed breakthrough (compared to chloride breakthrough) in both soils, followed by a constant effluent concentration ratio of less than unity indicating that degradation was occuring. The velocities for the chloro- and nitrophenols were in the range of 10-100% of the water velocity in the two subsoils. The distribution coefficient for the specific phenol, the acidity and the pH of the soil apparently governed the retardation of the phenolic compounds. Degradation of most of the phenols was observed with half-like values of 30-150 days. The four organophosphorus pesticides, Dimethoate ®, Malathion ®, Sulfotep ® and Fenitrothion ®, showed relative velocities from < 10% to ≈ 100%. Malathion ® and Sulfotep ® were degraded with half-life values of 10-20 days, while Dimethoate ® was not significantly degraded in the two soil columns. Fenitrothion ® did not appear in the effluent from the columns within the experimental period of time, probably due to high retardation.

Spatial analysis of subsoil compaction on cultivated land by means of penetrometry, electrical resistence tomography and X-ray computed tomography

NASA Astrophysics Data System (ADS)

Zumr, David; Vláčilová, Markéta; Dostál, Tomáš; Jeřábek, Jakub; Sobotková, Martina; Sněhota, Michal

2015-04-01

Soil compaction is a well recognized phenomena in the agricultural land. Various effects can alter the degree of the compaction in the field. The topsoil is regularly loosened due to agrotechnical operations, but the subsoil remains usually compacted. Various studies show increasing bulk density and decreasing saturated hydraulic conductivity in the plough pan, even though some authors argue that it does not have to be always the case due to presence of bio-macropores. Hence the structural properties of the subsoil and the spatial distribution of the compacted layer depth within the cultivated fields are important factors influencing soil water regime, nutrients regime and runoff generation. The aim of the contribution is to present the results of the monitoring of the plough pan depth spatial distribution at the experimental catchment Nucice (Central Bohemia, Czech Republic). The soils are classified as Luvisols and Cambisols with a loamy Ap horizon (0.1 - 0.2 m deep) underlined by a silty and silty-clay B horizon. The content of clay particles in the topsoil is around 8%. The soil has low inner aggregate (soil matrix) hydraulic conductivity, with measured values of approximately 0.1 - 2 cm d-1. The bulk topsoil saturated hydraulic conductivity (Ks) is significantly higher and varies depending on the season. To observe the divide between topsoil and subsoil layers in detail and to be able to compare the soil structure and pore networks of both layers we inspected undisturbed soil samples with X-ray computed tomography. The divide between the conservatively tilled topsoil and the subsoil is clearly observable also on terrain. To identify its exact position we implemented a combination of penetrometry, soil sampling and electrical resistance tomography (ERT). The penetration tests accompanied by soil probing were done in an irregular network across the whole catchment based on the slopes and distance to the stream. Several 2D ERT measurements were done locally on a plot of approximately 10 x 50 m. Dipole-dipole scheme with electrode span of 10 cm was used. The results obtained by different techniques are in a good agreement with observed plough pan position. The contribution was prepared within the project of Czech Science Foundation No. 13-20388P. We thank Johannes Koestel from SLU Uppsala for his great help during CT imaging of the soil samples.

Management of source and drinking-water quality in Pakistan.

PubMed

Aziz, J A

2005-01-01

Drinking-water quality in both urban and rural areas of Pakistan is not being managed properly. Results of various investigations provide evidence that most of the drinking-water supplies are faecally contaminated. At places groundwater quality is deteriorating due to the naturally occurring subsoil contaminants or to anthropogenic activities. The poor bacteriological quality of drinking-water has frequently resulted in high incidence of waterborne diseases while subsoil contaminants have caused other ailments to consumers. This paper presents a detailed review of drinking-water quality in the country and the consequent health impacts. It identifies various factors contributing to poor water quality and proposes key actions required to ensure safe drinking-water supplies to consumers.

Experimental sensitivity analysis of subsoil-slab behaviour regarding degree of fibre-concrete slab reinforcement

NASA Astrophysics Data System (ADS)

Hrubesova, E.; Lahuta, H.; Mohyla, M.; Quang, T. B.; Phi, N. D.

2018-04-01

The paper is focused on the sensitivity analysis of behaviour of the subsoil – foundation system as regards the variant properties of fibre-concrete slab resulting into different relative stiffness of the whole cooperating system. The character of slab and its properties are very important for the character of external load transfer, but the character of subsoil cannot be neglected either because it determines the stress-strain behaviour of the all system and consequently the bearing capacity of structure. The sensitivity analysis was carried out based on experimental results, which include both the stress values in soil below the foundation structure and settlements of structure, characterized by different quantity of fibres in it. Flat dynamometers GEOKON were used for the stress measurements below the observed slab, the strains inside slab were registered by tensometers, the settlements were monitored geodetically. The paper is focused on the comparison of soil stresses below the slab for different quantity of fibres in structure. The results obtained from the experimental stand can contribute to more objective knowledge of soil – slab interaction, to the evaluation of real carrying capacity of the slab, to the calibration of corresponding numerical models, to the optimization of quantity of fibres in the slab, and finally, to higher safety and more economical design of slab.

Clay illuviation provides a long-term sink for C sequestration in subsoils

NASA Astrophysics Data System (ADS)

Torres-Sallan, Gemma; Schulte, Rogier P. O.; Lanigan, Gary J.; Byrne, Kenneth A.; Reidy, Brian; Simó, Iolanda; Six, Johan; Creamer, Rachel E.

2017-04-01

Soil plays a key role in the global carbon (C) cycle. Most current assessments of SOC stocks and the guidelines given by Intergovernmental Panel on Climate Change (IPCC) focus on the top 30 cm of soil. Our research shows that, when considering only total quantities, most of the SOC stocks are found in this top layer. However, not all forms of SOC are equally valuable as long-term stable stores of carbon: the majority of SOC is available for mineralisation and can potentially be re-emitted to the atmosphere. SOC associated with micro-aggregates and silt plus clay fractions is more stable and therefore represents a long-term carbon store. Our research shows that most of this stable carbon is located at depths below 30 cm (42% of subsoil SOC is located in microaggregates and silt and clay, compared to 16% in the topsoil), specifically in soils that are subject to clay illuviation. This has implications for land management decisions in temperate grassland regions, defining the trade-offs between primary productivity and C emissions in clay-illuviated soils, as a result of drainage. Therefore, climate smart land management should consider the balance between SOC stabilisation in topsoils for productivity versus sequestration in subsoils for climate mitigation.

Small scale variability of transport and composition of dissolved organic matter in the subsoil

NASA Astrophysics Data System (ADS)

Leinemann, T.; Mikutta, R.; Kalbitz, K.; Guggenberger, G.

2016-12-01

Dissolved organic matter (DOM) is the most mobile fraction of carbon in the soil and connects the carbon-rich topsoil with the subsoil where translocated OM may get stabilized. The water flux in soil is highly heterogeneous, both temporarily and spatially. We, therefore, hypothesize that at high flow velocities, DOM can bypass possible mineral binding sites and microorganisms, thus leading to less degraded DOM under high flow velocities. To address this question, we investigated water and DOM fluxes in situ using segmented suction plates (4 x 4 segments on 24 x 24 cm) installed into three soil observatories at three depths (10 cm, 50 cm, and 150 cm) in a Dystric Cambisol under Beech (Fagus sylvatica) near Hannover, Germany. To follow the transport of carbon from the litter layer through the soil, an in situ 13C-labelling experiment has been conducted in January 2015. Concentration of dissolved organic carbon (DOC) and DOM composition was analyzed using high temperature combustion and photometric methods. The amount of transported DOC decreased by ca. 80 % from 10 to 50 cm depth and by 40 % from 50 to 150 cm depth. Different flow patterns existed at the centimeter scale, which were stable over time for individual suction plate segments. The specific UV280 nm absorbance of DOM decreased with increasing soil depth. This indicates a selective loss of aromatic compounds. The influence of different flow regimes on the DOM quality became apparent in the subsoil samples (>50 cm depth) showing a correlation of increasing UV280 nm absorbance with increasing water flux. The 13C-labelling experiment showed that after 10 month just 0.3 % of the DOC in 150 cm depth was derived from fresh litter. The transport of leaf litter carbon seemed to be controlled by the flow regime as the DO13C ratio and the water flux correlated positively. This can be an indication for the importance of preferential flow on carbon transport to the subsoil.

Rapid Turnover and Minimal Accretion of Mineral Soil Carbon During 60-Years of Pine Forest Growth on Previously Cultivated Land

NASA Astrophysics Data System (ADS)

Richter, D., Jr.; Mobley, M. L.; Billings, S. A.; Markewitz, D.

2016-12-01

At the Calhoun Long-Term Soil-Ecosystem field experiment (1957-present), reforestation of previously cultivated land over fifty years nearly doubled soil organic carbon (SOC) in surface soils (0 to 7.5-cm) but these gains were offset by significant SOC losses in subsoils (35 to 60-cm). Nearly all of the accretions in surface soils amounted to gains in light fraction SOC, whereas losses at depth were associated with silt and clay-sized particles. These changes are documented in the Calhoun Long-Term Soil-Ecosystem (LTSE) study that resampled soil from 16 plots about every five years and archived all soil samples from four soil layers within the upper 60-cm of mineral soil. We combined soil bulk density, density fractionation, stable isotopes, and radioisotopes to explore changes in SOC and soil organic nitrogen (SON) associated with five decades of the growth of a loblolly pine secondary forest. Isotopic signatures showed relatively large accumulations of contemporary forest-derived carbon in surface soils, and no accumulation of forest-derived carbon in subsoils. We interpret results to indicate that land-use change from cotton fields to secondary pine forests drove soil biogeochemical and hydrological changes that enhanced root and microbial activity and SOM decomposition in subsoils. As pine stands matured and are now transitioning to mixed pines and hardwoods, demands on soil organic matter for nutrients to support aboveground growth has eased due to pine mortality, and bulk SOM and SON and their isotopes in subsoils have stabilized. We anticipate major changes in the next fifty years as 1957 pine trees transition to hardwoods. This study emphasizes the importance of long-term experiments and deep soil measurements when characterizing SOC and SON responses to land use change. There is a remarkable paucity of E long-term soil data deeper than 30 cm.

Molecular multiproxy analysis of ancient root systems suggests strong alteration of deep subsoil organic matter by rhizomicrobial activity

NASA Astrophysics Data System (ADS)

Gocke, Martina; Huguet, Arnaud; Derenne, Sylvie; Kolb, Steffen; Wiesenberg, Guido L. B.

2013-04-01

Roots have a high potential capacity to store large amounts of CO2 in the subsoil. However, associated with rooting, microorganisms enter the subsoil and might contribute to priming effects of carbon mineralisation in the microbial hotspot rhizosphere. Although these processes are well known for recent surface soils, it remains questionable, if and how microorganisms contribute to priming effects in the subsoil and if these effects can be traced after the roots' lifetime. The current study implies several state-of-the-art techniques like DNA and lipid molecular proxies to trace remains of microbial biomass in ancient root systems. These can provide valuable information if parts of the root and rhizomicrobial biomass are preserved, e.g. by encrustation with secondary carbonate during the root's lifespan or shortly thereafter. At the Late Pleistocene loess-paleosol sequence near Nussloch (SW Germany), rhizoliths (calcified roots) occur highly abundant in the deep subsoil from 1 to 9 m depth and below. They were formed by Holocene woody vegetation. Their size can account for up to several cm in diameter and up to > 1 m length. Rhizoliths and surrounding sediment with increasing distances of up to 10 cm, as well as reference loess without visible root remains were collected at several depth intervals. Samples were analysed for n-fatty acids (FAs) and glycerol dialkyl glycerol tetraethers (GDGTs; membrane lipids from Archaea and some Bacteria), as well as structural diversity based on the RNA gene of the prokaryotic ribosome subunit 16S (16S rRNA). GDGT represent organic remains from microbial biomass, whereas FA comprise both microbial remains and degradation products. 16S rRNA indicates the presence of both living cells and/or cell fragments. Despite the general low RNA contents in the sample set, results pointed to a much higher abundance of bacterial compared to archaeal RNA. The latter occured in notable amounts only in some rhizoliths. This was in part enforced by decreasing contents of archeal GDGTs from rhizolith via rhizosphere towards root-free loess. Furthermore, the bacterial fingerprint revealed - similar to modern root systems - higher taxonomic diversity in rhizosphere compared to rhizoliths and reference loess. This argues for microorganisms benefiting from root deposits and exudates. Highest concentrations of branched GDGTs in rhizoliths suggest that their source organisms feed on root remains. Incorporation of rhizomicrobial remains as represented by RNA and GDGTs usually affected the sediment at maximum to a distance of 2-3 cm from the former root. FA contents in rhizosphere showed strong scatter and were in part depleted compared to reference loess or, especially in deeper transects, enriched. This indicates the presence of degradation products originating from former rhizosphere processes. Especially at larger depth not affected by modern pedogenic processes, portions of mainly microbial derived C16 homologues were higher in rhizosphere loess up to distances of 10 cm, revealing that the possible extension of the rhizosphere was underestimated so far. In Corg poor subsoil, the occurence of diverse rhizosphere microorganisms and degradation processes even in several centimeters distant from roots point to a strong alteration of OM, possibly contributing to carbon mineralisation.

The Impact of Traditional Septic Tank Soakaway Systems and the Effects of Remediation on Water Quality in Ireland

NASA Astrophysics Data System (ADS)

Kilroy, Kate; Keggan, Mary; Barrett, Maria; Dubber, Donata; Gill, Laurence W.; O'Flaherty, Vincent

2014-05-01

In Ireland the domestic wastewater of over 1/3 of the population is treated by on-site systems. These systems are based on a traditional design for disposal of domestic wastewater and rely on the surrounding subsoil for further treatment. Inefficient treatment is often associated with these systems and can cause pollution of local aquifers and waterways. The effluent nutrient load can contribute to eutrophication, depletion of dissolved oxygen and excessive algae growth in surface water bodies. Human enteric pathogens associated with faecal pollution of water sources may promote the outbreak of disease through contamination of drinking water supplies. The subsoil attenuation plays an important role in the protection of groundwater from effluent pollution. Therefore, as over 25% of the countries domestic water supplies are provided by groundwater, the protection of groundwater resources is crucial. This project involves both the assessment of traditional septic tank soakaway systems and the effects of remediation in low permeability subsoil settings on water quality in Ireland. The study aims to confirm by microbial source tracking (MST), the source (human and/or animal) of faecal microorganisms detected in groundwater, surface water and effluent samples, and to monitor the transport of pathogens specific to on-site wastewater outflows. In combination with MST, the evaluation of nitrification and denitrification in surrounding soil and effluent samples aims to assess nitrogen removal at specific intervals; pre-remediation and post-remediation. Two experimental sites have been routinely sampled for effluent, soil and groundwater samples as well as soil moisture samples using suction lysimeters located at various depths. A robust and reproducible DNA extraction method was developed, applicable to both sites. MST markers based on host-specific Bacteriodales bacteria for universal, human and cow-derived faecal matter are being employed to determine quantitative target occurrence using real-time Polymerase Chain Reaction (qPCR) assays (Kildare et al., 2007). The abundance of both archaeal and bacterial 16S rRNA and of several functional nitrification and denitrification genes (i.e., amoA, nirS, nirK, and nosZ) is also being determined and compared in both sites. Ultimately, this novel project aims to assess the effectiveness of remediation at reducing the risk of pathogen transport and nitrate loading to local ground and surface waters. Results from both sites suggest low permeability subsoil prevents the even distribution of effluent through the receiving subsoil, forcing it instead to flow laterally via distinct pathways such as sand lenses and nearby drainage routes. This affects the ability of the subsoil to sufficiently treat the percolating effluent. Initial results from the remediation of the existing systems to alternative low pressure systems indicate a positive impact towards the groundwater quality of both sites. This step towards a better understanding of the factors influencing microbial denitrification and the behaviour of pathogens in sensitive environments aids in identifying management options for reducing nitrous oxide (N2O) emissions and nitrate (NO3-) leaching; and for enhanced protection of public health.

Characteristics of organic matter fractions separated by wet-sieving and differences in density from five soils of different pedogenesis under mature beech forest.

NASA Astrophysics Data System (ADS)

Vormstein, Svendja; Kaiser, Michael; Ludwig, Bernard

2017-04-01

Forest top- and subsoil account for approximately 70 % of the organic C (OC) globally stored in soil reasoning their large importance for terrestrial ecosystem services such as the mitigation of climate change. In contrast to forest topsoil, there is much less information about the decomposition and stabilization of organic matter (OM) in subsoil. Therefore, we sampled the pedogenetic horizons of five soils under mature beech forest developed on different parent material (i.e. Tertiary Sand, Loess, Basalt, Lime Stone, Red Sandstone) down to the bedrock. The bulk soil samples were characterized for texture, oxalate and dithionite soluble Fe and Al, pH, OC, microbial biomass C and basal respiration (cumulative CO2 emission after 7 and 14 days). Furthermore, we analyzed aggregate size fractions separated by wet-sieving (i.e. >1000 µm, 1000-250 µm, 250-53 µm, <53 µm) and density fractions separated using NaPT (i.e. light, occluded light, and heavy fraction) from the soil horizon specific samples. The OC of the topsoil (Ah horizon) on Lime Stone and Red Sandstone was predominately stored in the larger macro-aggregates (>1000 µm). In contrast, the major part of the topsoil OC on Basalt and Tertiary Sand was found in the smaller macro-aggregates (1000-250 µm). For the topsoil samples, we found that the basal respiration as well as the microbial biomass C were positively correlated (p ≤0.05) with the OC amounts associated with the free and occluded light fraction and with the macro-aggregates (1000-250 µm) and micro-aggregates (250-53 µm) suggesting these fractions to store the major part of the easily decomposable OM. The OC amount associated with the heavy fraction and the fraction <53 µm was correlated with the contents of oxalate and dithionite soluble Fe and Al suggesting interactions between organic compounds and Fe- and Al-oxides to be highly important for the OM stabilization in forest topsoil. In the subsoil (horizons below the Ah), the contribution of the OC associated with the aggregate size fractions <250 µm to the OC stored in the subsoil increased with depth. The OC contents associated with the free and occluded light as well as the heavy fraction and with the aggregate size fractions >53 µm were positively correlated with basal respiration and the microbial biomass C. This suggests, in contrast to the topsoil, the easily decomposable OM to be distributed more homogeneously among fractions. Only the OC content of the <53 µm fraction showed positive correlations to soil mineral characteristics such as the contents of clay oxalate and dithionite soluble Fe or Al and no relationship to the basal respiration and microbial biomass C. This indicates the OM associated with this fraction to be most diagnostic for the amount of OC stabilized against microbial decay in the subsoil and interactions between OM and oxides as well as layer silicates to be relevant stabilization mechanisms. The results point toward similar OM stabilization mechanisms in the analysed forest top- and subsoils but revealed differences in the distribution of easily decomposable OM within the soil matrix.

Micro-scale heterogeneity of soil phosphorus depends on soil substrate and depth

DOE PAGES

Werner, Florian; Mueller, Carsten W.; Thieme, Jurgen; ...

2017-06-09

Soils comprise various heterogeneously distributed pools of lithogenic, free organic, occluded, adsorbed, and precipitated phosphorus (P) forms, which differ depending on soil forming factors. Small-scale heterogeneity of element distributions recently has received increased attention in soil science due to its influence on soil functions and soil fertility. We investigated the micro-scale distribution of total P and different specific P binding forms in aggregates taken from a high-P clay-rich soil and a low-P sandy soil by combining advanced spectrometric and spectroscopic techniques to introduce new insights on P accessibility and availability in soils. Here we show that soil substrate and soilmore » depth determine micro-scale P heterogeneity in soil aggregates. In P-rich areas of all investigated soil aggregates, P was predominantly co-located with aluminium and iron oxides and hydroxides, which are known to strongly adsorb P. Clay minerals were co-located with P only to a lesser extent. In the low-P topsoil aggregate, the majority of the P was bound organically. Aluminium and iron phosphate predominated in the quartz-rich low-P subsoil aggregate. Sorbed and mineral P phases determined P speciation in the high-P top- and subsoil, and apatite was only detected in the high-P subsoil aggregate. Lastly, our results indicate that micro-scale spatial and chemical heterogeneity of P influences P accessibility and bioavailability.« less

Micro-scale heterogeneity of soil phosphorus depends on soil substrate and depth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Werner, Florian; Mueller, Carsten W.; Thieme, Jurgen

Soils comprise various heterogeneously distributed pools of lithogenic, free organic, occluded, adsorbed, and precipitated phosphorus (P) forms, which differ depending on soil forming factors. Small-scale heterogeneity of element distributions recently has received increased attention in soil science due to its influence on soil functions and soil fertility. We investigated the micro-scale distribution of total P and different specific P binding forms in aggregates taken from a high-P clay-rich soil and a low-P sandy soil by combining advanced spectrometric and spectroscopic techniques to introduce new insights on P accessibility and availability in soils. Here we show that soil substrate and soilmore » depth determine micro-scale P heterogeneity in soil aggregates. In P-rich areas of all investigated soil aggregates, P was predominantly co-located with aluminium and iron oxides and hydroxides, which are known to strongly adsorb P. Clay minerals were co-located with P only to a lesser extent. In the low-P topsoil aggregate, the majority of the P was bound organically. Aluminium and iron phosphate predominated in the quartz-rich low-P subsoil aggregate. Sorbed and mineral P phases determined P speciation in the high-P top- and subsoil, and apatite was only detected in the high-P subsoil aggregate. Lastly, our results indicate that micro-scale spatial and chemical heterogeneity of P influences P accessibility and bioavailability.« less

Erodibility of waste (Loess) soils from construction sites under water and wind erosional forces.

PubMed

Tanner, Smadar; Katra, Itzhak; Argaman, Eli; Ben-Hur, Meni

2018-03-01

Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0-0.3m) and subsoil layers (0.3-0.9 and >1m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility (K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. Copyright © 2017 Elsevier B.V. All rights reserved.

Biomat development in soil treatment units for on-site wastewater treatment.

PubMed

Winstanley, H F; Fowler, A C

2013-10-01

We provide a simple mathematical model of the bioremediation of contaminated wastewater leaching into the subsoil below a septic tank percolation system. The model comprises a description of the percolation system's flows, together with equations describing the growth of biomass and the uptake of an organic contaminant concentration. By first rendering the model dimensionless, it can be partially solved, to provide simple insights into the processes which control the efficacy of the system. In particular, we provide quantitative insight into the effect of a near surface biomat on subsoil permeability; this can lead to trench ponding, and thus propagation of effluent further down the trench. Using the computed vadose zone flow field, the model can be simply extended to include reactive transport of other contaminants of interest.

The methodology of choice Cam-Clay model parameters for loess subsoil

NASA Astrophysics Data System (ADS)

Nepelski, Krzysztof; Błazik-Borowa, Ewa

2018-01-01

The paper deals with the calibration method of FEM subsoil model described by the constitutive Cam-Clay model. The four-storey residential building and solid substrate are modelled. Identification of the substrate is made using research drilling, CPT static tests, DMT Marchetti dilatometer, and laboratory tests. Latter are performed on the intact soil specimens which are taken from the wide planning trench at the depth of foundation. The real building settlements was measured as the vertical displacement of benchmarks. These measurements were carried out periodically during the erection of the building and its operation. Initially, the Cam Clay model parameters were determined on the basis of the laboratory tests, and later, they were corrected by taking into consideration numerical analyses results (whole building and its parts) and real building settlements.

Long-term impact of land management in soil biological processes can be assessed by fingerprint of dissolved organic carbon and peroxidase activity in topsoil and subsoil

NASA Astrophysics Data System (ADS)

Hernandez-Soriano, Maria C.; Maclean, Jamie L.; Dalal, Ram C.; Menzies, Neal W.; Kopittke, Peter M.

2015-04-01

The dissolved organic carbon (DOC) is a highly dynamic pool, directly related to biological functions and to the stabilization of organic carbon (OC) through interaction with the mineral phase. Therefore, the characterization of the main components of DOC can be linked to the metabolic status of soil and the turnover of OC and provides a sensitive approach to evaluate the impact of land use on OC turnover in soils. Accordingly, the objective of this study was to derive relationships between DOC characteristics and biochemical activity in soils under contrasting land management. The soil solution was isolated from topsoil and subsoil for three soils (Vertisol, Ferralsol, Acrisol, World Reference Base 2014) collected from undisturbed areas and from a location(s) immediately adjacent which has a long history of agricultural, pasture or afforestation use (>20 years) by centrifugation at 4000 rpm (20 min, 25 °C. The fingerprint of DOC was obtained to identify OC functionalities by spectrofluorometric analyses and Excitation-Emission matrices (EEM) were obtained for all samples. The excitation wavelengths were increased from 250 to 400 nm in 5-nm steps for each excitation wavelength, and emission was detected from 250 to 500 nm in 0.5-nm steps and. Humification index (HIX), freshness index (FrI), fluorescence index (FI) and redox index (RI) were derived from the EEMs. Extracellular laccase activity was examined by monitoring the oxidation of 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) at 420 nm. The EEMs revealed a depletion of the humic-like component (250Acrisol>Ferralsol and was always higher for the topsoils compared to the corresponding subsoils. Overall, results indicate that land management has a strong impact on soil biological activity. Importantly, such impact is directly linked to changes in the composition of soil OC, particularly the transformation of OC inputs into oxidized products that can contribute to OC build up in soil. For the first time, we have utilized DOC fingerprinting and extracellular laccase activity as complementary techniques to examine changes in OC speciation in soil solutions. This approach provides a suitable link between variations in biological functions and OC dynamics.

Pasture management controls soil organic matter stocks, properties, and biochemical functioning in Tibetan grasslands

NASA Astrophysics Data System (ADS)

Spielvogel, Sandra; Breidenbach, Andreas; de la Haye, Tilman; Schleuß, Per; Kuzyakov, Yakov; Guggenberger, Georg

2016-04-01

The Tibetan Plateau hosts the highest and largest pasture ecosystem worldwide, and provides tremendous sinks for carbon. Due to the sheer size of the of the Tibetan Plateau, feedback effects of soil organic carbon (OC) losses from inadequate grassland management are of undisputed relevance for ecosystem stability and future global change scenarios. Given the vital importance of the Tibetan steppes as global OC sinks, we combined data on OC stocks from own studies with an extensive literature review on soils developed under montane and alpine Kobresia pygmaea and Stipa grandis pastures. We calculated soil OC stocks at the Tibetan Plateau within the first 30 cm of the soil profile depending on pasture management and climate. Vertical gradients of δ13C values, neutral sugar, cutin and suberin contents, lignin phenol contents as well as microbial community composition (t-RFLP analysis, 16S rDNA und IST sequencing) and activities of six extracellular enzymes involved in the C, N, and P cycle were assessed. The depth gradients of these parameters reflected degradation processes from intact Kobresia pastures (stage 0) to pronounced degradation (bare soil; stage 5). Moderate husbandry is beneficial for the storage of OC, nitrogen (N) and other nutrients (e.g. phosphorus) for the majority of the montane grasslands of the Tibetan Plateau (i.e., Kobresia pygmaea pastures). However, Kobresia root mats originated from grazing are affected by desiccations and frost, which cause polygonal cracking and initiates soil erosion. This process is accelerated under high grazing pressure (overgrazing) that enhances root mat degradation. Increasing degradation caused by large herbivore densities resulted in an increased OC decomposition demonstrated by decreasing δ13C values. The δ13C shift towards more negative values reflects the relative enrichment of 13C depleted lignin components during OC decomposition in the strongly disturbed soil. Translocation of topsoil material into the subsoil with advancing degradation (from stages 1 to 5) was indicated by increasing contributions of cutin to OC in the subsoils. Microbial community composition in the subsoil changed progressively from stage 1 to 5 with most pronounced changes of the fungal community. These findings were confirmed by the enzyme activities involved in the degradation of more complex OC compounds (e.g. fungal phenoloxidases) that were highest in the subsoil of degradation stage 4. In contrast, degradation stages 2 and 3 showed low enzyme activities in the subsoil if related to soil OC amount. We conclude that pasture degradation decreases not only the mechanical protection of soil surface by Kobresia root mats, but also changes their biochemical and microbial functions. Moderate grazing improves the pastures, increases OC sequestration and may stop the degradation of soils on Tibetan plateau.

Source and compositional changes of soil organic matter in an acidic forest soil - from top- to subsoil

NASA Astrophysics Data System (ADS)

Angst, Gerrit; John, Stephan; Rethemeyer, Janet; Kögel-Knabner, Ingrid; Mueller, Carsten W.

2014-05-01

Subsoils can significantly contribute to the terrestrial C pool. While processes of C turnover and storage in topsoils are generally well understood, little is known about subsoils. Our project, embedded within the DFG research group FOR 1806, aims to contribute to the knowledge about subsoil C by differentiating soil organic matter (SOM) in terms of its origin and its composition. In order to obtain a meaningful sample set we studied three soil ditches, 3.15 m in length and 2.15 m in depth, in a podzolic Cambisol under European beech (Fagus sylvatica L.) north of Hannover, Germany. In a to date unique sampling approach we took 64 soil samples in a regular vertical grid in each of the soil profiles, thus identifying possible gradients between top- and subsoil. The samples were subjected to a combined density and particle size fractionation to separate particulate organic matter (POM) from mineral compartments. We especially aimed at obtaining the combined fine silt and clay fraction which is thought to be most important in the long term stabilization of SOM. The chemical composition of the so obtained fractions and the bulk soil was revealed by C, N and 13C CPMAS NMR measurements. The source of OM in the soil was investigated by tracing the biopolymers cutin and suberin across the soil profile. Cutin occurs mainly in the cuticula of leaves while suberin mainly constitutes the endodermal cell walls of plant roots. In soils the two polymers can thus be used as proxies for above and belowground OM input respectively. To release the constituting monomers of the two biopolymers from the soil samples the latter were pretreated with organic solvents to extract free lipids. The soil residues were subsequently subjected to a base hydrolysis and the so obtained extracts were measured with GC/MS. The organic C contents of the bulk soil decrease significantly with depth in all transects from around 15 mg g-1 to 2 mg g-1. This is likely associated with the very high sand and low clay concentrations and the decreasing POM content at greater depths in the soil profiles. The highest C contents were found in the POM fractions with 400 mg g-1 and the combined fine silt and clay fractions with 6 mg g-1. Interestingly the NMR spectra display an already highly processed POM in the uppermost soil horizon as indicated by high alkyl/O-alkyl C ratios. This, together with the absence of POM in greater depths, points towards a decomposition of aboveground OM predominantly in the upper zones of the soil and a confined root input to deeper soil regions.

Testing radon mitigation techniques in a pilot house from Băiţa-Ştei radon prone area (Romania).

PubMed

Cosma, Constantin; Papp, Botond; Cucoş Dinu, Alexandra; Sainz, Carlos

2015-02-01

This work presents the implementation and testing of several radon mitigation techniques in a pilot house in the radon prone area of Băiţa-Ştei in NW part of Romania. Radon diagnostic investigations in the pilot house showed that the main source of radon was the building sub-soil and the soil near the house. The applied techniques were based on the depressurization and pressurization of the building sub-soil, on the combination of the soil depressurization system by an electric and an eolian fans. Also, there was made an application of a radon barrier membrane and a testing by the combination of the radon membrane by the soil depressurization system. Finally, the better obtained remedial efficiency was about 85%. Copyright © 2014 Elsevier Ltd. All rights reserved.

MAHA: A comprehensive system for the storage and visualization of subsoil data for seismic microzonation

NASA Astrophysics Data System (ADS)

Di Felice, P.; Spadoni, M.

2013-04-01

MAHA is a database-centred software system for the storage and visualization of subsoil data used for the production of seismic microzonation maps in Italy. The application was implemented using open source software in order to grant its maximum diffusion and customization. A conceptual model of the subsoil, jointly developed by the Italian National Research Council and the National Department of Civil Protection, inspired the structure of the underlying database, consisting of 15 tables, 3 of which of spatial nature to accommodate geo-referenced data associated to points, lines and polygons. A web-GIS interface acts as a bridge between the user and the database, drives the input of geo-referenced data and enables the users to formulate different types of spatial queries. A series of forms designed "ad hoc" and enriched with combo boxes provide guided procedures to maximize the fluency of data entry and to reduce the possibility of erroneous typing. One of these procedures helps to transform the descriptions of the geological units (granular materials), given in technical paper documents by using a conversational style, into standardized numeric codes. Summary reports, produced in the pdf format, can be generated through decoding and graphic display of the parameters previously entered in the database. MAHA was approved by the national commission for seismic microzonation established by the Italian Prime Minister and, in the next years, it is expected to significantly support the entire process of map production in the urban areas more exposed to seismic hazard.

[Effect of long-term fertilizing regime on soil microbial diversity and soil property].

PubMed

Li, Chenhua; Zhang, Caixia; Tang, Lisong; Xiong, Zhengqin; Wang, Baozhan; Jia, Zhongjun; Li, Yan

2014-03-04

To evaluate the effect of long-term fertilization on soil microbial community and soil chemical and physical properties. Using a high-throughput pyrosequencing technique, we studied microbial community in the 0-300 cm soil samples covering a 20-year field-experiment with different fertilization applications including inorganic fertilizer alone (N 300 kg/hm2, P2O5 150 kg/hm2 and K2O 60 kg/hm2) and inorganic fertilizer combined with straw (same application rate of N and P fertilizer combined with 5.4 t straw). Actinobacteria and alpha-proteobacteria were the predominant groups in the topsoil (0-20 cm). As the soil depth increased, the relative abundance of actinobacteria decreased whereas that of proteobacteria, especially gamma-proteobacteria and beta-proteobacteria increased and gradually became the dominant groups in the subsoil (20-300 cm). Long-term fertilizing applications significantly affected soil microbial communities throughout the soil profile, and increased the relative abundance of ammonia-oxidizing archaea at 0-40 cm depth. In addition, agriculture management, e. g. irrigation may be an important driving factor for the distribution of ammonia-oxidizing bacteria in soil profile. Total nitrogen and organic carbon contents were the most influential factors on microbial community in the topsoil and in the subsoil, respectively. Long-term fertilizer applications altered soil nutrient availability within the soil profile, which was likely to result in the different microbial community structure between the fertilizer treatments, especially for the subsoil.

Yellow-Poplar Rooting Habits

Treesearch

John K. Francis

1979-01-01

Although the configuration of pole-sized yellow-poplar root systems in Tennessee is quite variable, a branched taproot with several widely spreading laterals is typical. Rooting depth is particularly limited by clayey texture, wetness, and firmness of subsoils.

Contrasting effects of deep ploughing of croplands and forests on SOC stocks and SOC bioavailability

NASA Astrophysics Data System (ADS)

Alcántara, Viridiana; Don, Axel; Vesterdal, Lars; Well, Reinhard; Nieder, Rolf

2016-04-01

Subsoils are essential within the global C cycle since they have a high soil organic carbon (SOC) storage capacity due to a high SOC saturation deficit. However, measures for enhancing SOC stocks commonly focus on topsoils. We assessed the long-term stability of topsoil SOC buried in cropland and forest subsoils by deep ploughing. Deep ploughing was promoted until the 1970s for breaking up hardpan and improving soil structure to optimize crop growth conditions. In forests deep ploughing is performed as a site preparation measure for afforestation of sandy soil aiming at increasing water availability in deeper layers and decreasing weed competition by burial of seeds. An effect of deep ploughing was the translocation of topsoil SOC into subsoils, with a concomitant mixing of SOC-poor subsoil material into the "new" topsoil horizon. Deep ploughed croplands and forests represent unique long-term "in-situ incubations" of SOC-rich material in subsoils in order to assess the effect of soil depth on SOC turnover. In this study, we sampled soil from five loamy and five sandy cropland sites as well as from five sandy forest sites, which were ploughed to 55-127 cm depth 25 to 53 years ago. Adjacent, equally managed but conventionally ploughed or not ploughed (forests) subplots were sampled as reference. On average 45 years after the deep ploughing operation, at the cropland sites, the deep ploughed soils contained 42±13 Mg ha-1 more SOC than the reference subplots down to 100 cm depth. On the contrary, at the forest sites, the SOC stocks of the deep ploughed soils contained 18±9 Mg ha-1 less SOC compared to the reference soils on average 38 years deep ploughing. These contrasting results can be explained, on the one hand, by the slower SOC accumulation in the newly formed topsoils of the deep ploughed forest soil (on average 48% lower SOC stocks in topsoil) compared to the croplands (on average 15% lower SOC stocks in topsoil). On the other hand, the buried topsoils at the forest sites exhibited similar bioavailability of SOC (measured as net C mineralization rates from short-term in-vitro incubations) as compared to the reference topsoils. In contrast, at the sandy cropland sites, net C mineralization rates were significantly lower (67%) in the buried topsoil material compared to the reference topsoil. Buried SOC in the sandy soils is thus highly stable. Together with these results, we will present data on SOC fractions and discuss their implications for our view on stability of buried SOC in croplands and forests. Our results show that deep ploughing contributes to SOC sequestration by enlarging the storage space for SOC-rich material but only under the preconditions that i) burial is accompanied by decrease in SOC bioavailability and ii) SOC accumulates considerably in the newly formed topsoil.

Model development for prediction of soil water dynamics in plant production.

PubMed

Hu, Zhengfeng; Jin, Huixia; Zhang, Kefeng

2015-09-01

Optimizing water use in agriculture and medicinal plants is crucially important worldwide. Soil sensor-controlled irrigation systems are increasingly becoming available. However it is questionable whether irrigation scheduling based on soil measurements in the top soil could make best use of water for deep-rooted crops. In this study a mechanistic model was employed to investigate water extraction by a deep-rooted cabbage crop from the soil profile throughout crop growth. The model accounts all key processes governing water dynamics in the soil-plant-atmosphere system. Results show that the subsoil provides a significant proportion of the seasonal transpiration, about a third of water transpired over the whole growing season. This suggests that soil water in the entire root zone should be taken into consideration in irrigation scheduling, and for sensor-controlled irrigation systems sensors in the subsoil are essential for detecting soil water status for deep-rooted crops.

Analysis of the Vibration Propagation in the Subsoil

NASA Astrophysics Data System (ADS)

Jastrzębska, Małgorzata; Łupieżowiec, Marian; Uliniarz, Rafał; Jaroń, Artur

2015-02-01

The paper presents in a comprehensive way issues related to propagation in a soil environment of vibrations originating during sheet piling vibratory driving. Considerations carried out comprised the FEM analysis of initial-boundary behaviour of the subsoil during impacts accompanying the works performed. The analysis has used the authors' RU+MCC constitutive model, which can realistically describe complex deformation characteristics in soils in the field of small strains, which accompany the phenomenon of shock propagation. The basis for model creation and for specification of material parameters of the presented model consisted of first-class tests performed in a triaxial apparatus using proximity detectors guaranteeing a proper measurement of strains ranging from 10-1 to 10-3% and bender elements. Results obtained from numerical analyses were confronted with results of field tests consisting in measurements of acceleration amplitudes generated on the ground surface due to technological impacts versus the distance from vibration source.

Rate of hydrolysis and degradation of the cyanogenic glycoside - dhurrin - in soil.

PubMed

Johansen, Henrik; Rasmussen, Lars Holm; Olsen, Carl Erik; Bruun Hansen, Hans Christian

2007-02-01

Cyanogenic glycosides are common plant toxins. Toxic hydrogen cyanide originating from cyanogenic glycosides may affect soil processes and water quality. In this study, hydrolysis, degradation and sorption of dhurrin (4-hydroxymandelonitrile-beta-d-glucoside) produced by sorghum has been studied in order to assess its fate in soil. The log K(ow) of dhurrin was -1.18+/-0.08 (22 degrees C). Hydrolysis was a first-order reaction with respect to dhurrin and hydroxyl ion concentrations. Half lives ranged from 1.2h (pH 8.6; 25 degrees C) to 530d (pH 4; 25 degrees C). The activation energy of hydrolysis was 112+9kJ. At pH 5.8 and room temperature, addition of humic acids (50gl(-1)) increased the rate of hydrolysis tenfold, while addition of kaolinite or goethite (100-250gl(-1)) both decreased the rate considerably. No significant sorption to soil components could be observed. The degradation rates of dhurrin in top and subsoils of Oxisols, Ultisols, Alfisols and Mollisols were studied at 22 degrees C (25mgl(-1), soil:liquid 1:1 (w:V), pH 3.8-8.1). Half-lives were 0.25-2h for topsoils, and 5-288h in subsoils. Hydrolysis in solution explained up to 45% of the degradation in subsoils whereas the contribution in topsoils was less than 14%, indicating the importance of enzymatic degradation processes. The highest risk of dhurrin leaching will take place when the soil is a low activity acid shallow soil with low content of clay minerals, iron oxides and humic acids.

Determining and representing width of soil boundaries using electrical conductivity and MultiGrid

NASA Astrophysics Data System (ADS)

Greve, Mogens Humlekrog; Greve, Mette Balslev

2004-07-01

In classical soil mapping, map unit boundaries are considered crisp even though all experienced survey personnel are aware of the fact, that soil boundaries really are transition zones of varying width. However, classification of transition zone width on site is difficult in a practical survey. The objective of this study is to present a method for determining soil boundary width and a way of representing continuous soil boundaries in GIS. A survey was performed using the non-contact conductivity meter EM38 from Geonics Inc., which measures the bulk Soil Electromagnetic Conductivity (SEC). The EM38 provides an opportunity to classify the width of transition zones in an unbiased manner. By calculating the spatial rate of change in the interpolated EM38 map across the crisp map unit delineations from a classical soil mapping, a measure of transition zone width can be extracted. The map unit delineations are represented as transition zones in a GIS through a concept of multiple grid layers, a MultiGrid. Each layer corresponds to a soil type and the values in a layer represent the percentage of that soil type in each cell. As a test, the subsoil texture was mapped at the Vindum field in Denmark using both the classical mapping method with crisp representation of the boundaries and the new map with MultiGrid and continuous boundaries. These maps were then compared to an independent reference map of subsoil texture. The improvement of the prediction of subsoil texture, using continuous boundaries instead of crisp, was in the case of the Vindum field, 15%.

Heavy metal leaching from mine tailings as affected by plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, D.; Schwab, A.P.; Banks, M.K.

A column experiment was conducted to determine the impact of soil cover and plants on heavy metal leaching from mine tailings and heavy metal contaminated soil. Columns made of PVC were constructed with 30 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm of clean topsoil. Two grasses, tall fescue (Festuca arundinacea Schreb.) and big bluestem (Andropogon gerardii), were grown in the columns. The columns were leached at a slow rate for 1 yr with a 0.001 Mmore » CaCl{sub 2} solution under unsaturated conditions. The presence of both tall fescue and big bluestem increased Zn and Cd concentrations in the leachate. Lead concentrations in leachates were not affected by the presence of plants. Although plants generally reduced the total amount of water leached, total mass of Zn and Cd leached generally was not impacted by plants. Total mass of Pb leached was positively correlated with total leachate collected from each column. Covering the mine tailings with 60 cm of topsoil increased the mass of Zn and Cd leached relative to no topsoil. When the subsoil was absent, Zn and Cd leaching increased by as much as 20-fold, verifying the ability of soil to act as a sink for metals. Mine tailing remediation by establishing vegetation can reduce Pb movement but may enhance short-term Cd and Zn leaching. However, the changes were relatively small and do not outweigh the benefits of using vegetation in mine tailings reclamation.« less

[Effects of different straw recycling and tillage methods on soil respiration and microbial activity].

PubMed

Li, Xiao-sha; Wu, Ning; Liu, Ling; Feng, Yu-peng; Xu, Xu; Han, Hui-fang; Ning, Tang-yuan; Li, Zeng-jia

2015-06-01

To explore the effects of different tillage methods and straw recycling on soil respiration and microbial activity in summer maize field during the winter wheat and summer maize double cropping system, substrate induced respiration method and CO2 release method were used to determine soil microbial biomass carbon, microbial activity, soil respiration, and microbial respiratory quotient. The experiment included 3 tillage methods during the winter wheat growing season, i.e., no-tillage, subsoiling and conventional tillage. Each tillage method was companied with 2 straw management patterns, i.e., straw recycling and no straw. The results indicated that the conservation tillage methods and straw recycling mainly affected 0-10 cm soil layer. Straw recycling could significantly improve the microbial biomass carbon and microbial activity, while decrease microbial respiratory quotient. Straw recycling could improve the soil respiration at both seedling stage and anthesis, however, it could reduce the soil respiration at filling stage, wax ripeness, and harvest stage. Under the same straw application, compared with conventional tillage, the soil respiration and microbial respiratory quotient in both subsoiling and no-tillage were reduced, while the microbial biomass carbon and microbial activity were increased. During the summer maize growing season, soil microbial biomass carbon and microbial activity were increased in straw returning with conservation tillage, while the respiratory quotient was reduced. In 0-10 cm soil layer, compared with conventional tillage, straw recycling with subsoiling and no-tillage significantly increased soil microbial biomass carbon by 95.8% and 74.3%, and increased soil microbial activity by 97.1% and 74.2%, respectively.

Soil Profile Observations Relating to Drouth Damage in Black Willow Stands

Treesearch

WIlliam R. Beaufait

1955-01-01

During drouth, black willow (Salix nigra Karsh.) is quite sensitive to subsoil differences. Surface inspection alone rarely gives an adequate clue to the quality of the variously stratified alluvial soils on which willow may occur.

Tomography 3D models of S wave from cross-correlation of seismic noise to explore irregularities of subsoil under the artificial lake of Chapultepec Park

NASA Astrophysics Data System (ADS)

Cárdenas-Soto, M.; Valdes, J. E.; Escobedo-Zenil, D.

2013-05-01

In June 2006, the base of the artificial lake in Chapultepec Park collapsed. 20 thousand liters of water were filtered to the ground through a crack increasing the dimensions of initial gap. Studies indicated that the collapse was due to saturated material associated with a sudden and massive water filtration process. Geological studies indicates that all the area of this section the subsoil is composed of vulcano-sedimentary materials that were economically exploited in the mid-20th century, leaving a series of underground mines that were rehabilitated for the construction of the Park. Currently, the Lake is rehabilitated and running for recreational activities. In this study we have applied two methods of seismic noise correlation; seismic interferometry (SI) in time domain and the Spatial Power Auto Correlation (SPAC) in frequency domain, in order to explore the 3D subsoil velocity structure. The aim is to highlight major variations in velocity that can be associated with irregularities in the subsoil that may pose a risk to the stability of the Lake. For this purpose we use 96 vertical geophones of 4.5 Hz with 5-m spacing that conform a semi-circular array that provide a length of 480 m around the lake zone. For both correlation methods, we extract the phase velocity associated with the dispersion characteristics between each pair of stations in the frequency range from 4 to 12 Hz. In the SPAC method the process was through the dispersion curve, and in SI method we use the time delay of the maximum amplitude in the correlation pulse, which was previously filtered in multiple frequency bands. The results of both processes were captured in 3D velocity volumes (in the case SI a process of traveltime tomography was applied). We observed that in the frequency range from 6 to 8 Hz, appear irregular structures, with high velocity contrast in relation with the shear wave velocity of surface layer (ten thick m of saturated sediments). One of these anomalies is related to areas where the lake was rehabilitated, but other ones are not reported in previous geophysical or geotechnical studies.

[Impact of tillage and nutrient management practices on the spring weed community in a winter wheat-summer maize rotation farmland].

PubMed

Wang, Neng Wei; Ge, Xiu Li; Li, Sheng Dong

2017-03-18

Conservation tillage and the weed diversity are two hot issues in the modern ecological agriculture. Although it is known that the diversity of weed would increase slightly in the farmland under conservation tillage, the interaction effects between the tillage and the nutrient management on the weed community are not clear. In this study, one wheat-maize rotation field located in Ji'nan, Shandong Province, was selected as the studying site. Different tillage methods (no-tillage, deep subsoiling, rotary tillage, deep tillage) and different nutrient managements (farmers routine, 480 kg N hm -2 per year; high production and efficiency, 360 kg N hm -2 per year; optimal management, 300 kg N hm -2 per year) were carried out for 3 years. The characteristics of the spring weed communities under different managements were investigated and compared. The results showed that there were 15 species in the spring weed communities in the test filed and Digitaria sanguinalis and Echinochloa crusgalli were the dominant species. The plots under no-tillage or deep subsoiling had higher weed densities compared with those under the deep tillage or rotary tillage. In terms of the effect of tillage on the weed community diversity, both species richness index and species evenness index were lowest but the community dominance index was highest in the plots under deep tillage. In terms of the effect of the nutrient management, with the increase of fertilizer application, both species richness and evenness index increased under the different tillage methods. The community dominance increased with the increasing fertilizer application under deep tillage or rotary tillage and vice versa under no-tillage, deep subsoiling. In terms of weed biomass, the plots under no-tillage or deep subsoiling had significantly higher weed biomass than those under the other two tillage methods. The plots under routine nutrient management had higher weed biomass than those under the other two nutrient managements. Among all these treatments, the plots under the combination treatment of no-tillage and routine nutrient management had the highest weed biomass. According to these results, it was implied that no-tillage and fertilization would improve species richness index, species evenness index, and the productivity of spring weed community in the wheat-maize farmland.

Assessment of mitigating embankment settlement with pile-supported approach slabs : final report.

DOT National Transportation Integrated Search

1999-12-01

Problems involving highway bridge approach settlement have been observed at many sites in Louisiana. In southeastern Louisiana, where subsoil settlement potential is the greatest, the bridge structures are usually lengthened in order to reduce the he...

Assessment of mitigating embankment settlement with pile-supported approach slabs : summary report.

DOT National Transportation Integrated Search

1999-12-01

Problems involving highway bridge approach settlement have been observed at many sites in Louisiana. In southeastern Louisiana, where subsoil settlement potential is the greatest, the bridge structures are usually lengthened in order to reduce the he...

19 CFR 10.762 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... subsoil and their natural resources; (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.762 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... subsoil and their natural resources; (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.762 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... subsoil and their natural resources; (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.762 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... subsoil and their natural resources; (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.762 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... subsoil and their natural resources; (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

Flood effects on efflux and net production of nitrous oxide in river floodplain soils

NASA Astrophysics Data System (ADS)

Riaz, Muhammad; Bruderer, Christian; Niklaus, Pascal A.; Luster, Jörg

2016-04-01

Floodplain soils are often rich in nutrients and exhibit high spatial heterogeneity in terms of geomorphology, soil environmental conditions and substrate availability for processes involved in carbon and nutrient cycling. In addition, fluctuating water tables lead to temporally changing redox conditions. In such systems, there are ideal conditions for the occurrence of hot spots and moments of nitrous oxide emissions, a potent greenhouse gas. The factors that govern the spatial heterogeneity and dynamics of N2O formation in floodplain soils and the surface efflux of this gas are not fully understood. A particular issue is the contribution of N2O formation in the subsoil to surface efflux. We studied this question in the floodplain of a restored section of the Thur river (NE Switzerland) which is characterized by a flashy flow regime. As a consequence, the floodplain soils are unsaturated most of the time. We showed earlier that saturation during flood pulses leads to short phases of generally anoxic conditions followed by a drying phase with anoxic conditions within aggregates and oxic conditions in larger soil pores. The latter conditions are conducive for spatially closely-coupled nitrification-denitrification and related hot moments of nitrous oxide formation. In a floodplain zone characterized by about one meter of young, sandy sediments, that are mostly covered by the tall grass Phalaris arundinacea, we measured at several time points before and after a small flood event N2O surface efflux with the closed-chamber method, and assessed N2O concentrations in the soil air at four different depths using gas-permeable tubings. In addition, we calculated the N2O diffusivity in the soil from Radon diffusivity. The latter was estimated in-situ from the recovery of Radon concentration in the gas-permeable tubings after purging with ambient air. All these data were then used to calculate net N2O production rates at different soil depths with the gradient method. In addition, temperature, volumetric water content, as well as ammonium, nitrate and dissolved organic carbon in the soil solution were monitored at different depths in the observation plots. During not flood-affected conditions we observed weak diffusive gradients between subsoil and top soil, and net N2O production was maximum in the top soil. During the drying phase after a flood, diffusive gradients between subsoil and topsoil were more pronounced, and net N2O production in the subsoil increased. At all conditions, N2O efflux was more strongly correlated with N2O concentrations in the subsoil than those in the top soil. The complex interactions between soil moisture on one hand, and C and N substrate limitation on the other hand in determining N2O production at different soil depths will be discussed. Finally, the results will be put into the context of our earlier and ongoing studies that aim at elucidating the governing factors of spatial heterogeneity and dynamics of N2O emissions in floodplain soils.

50 CFR 300.151 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... regulations that concern fishing for fishery resources over which Russia exercises sovereign rights or fishery... entity of its government. Russian continental shelf or continental shelf of Russia means the seabed and subsoil of the submarine areas over which, consistent with international law, Russia exercises sovereign...

19 CFR 10.802 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.862 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

.... “Person” means a natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (r) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.862 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

.... “Person” means a natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (r) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.802 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.802 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.862 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

.... “Person” means a natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (r) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.802 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.862 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... “Person” means a natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (r) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

19 CFR 10.802 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

.... “Person” means a natural person or an enterprise; (p) Preferential tariff treatment. “Preferential tariff... seabed and subsoil and their natural resources; and (t) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. Import Requirements ...

Amelioration of an Ultisol profile acidity using crop straws combined with alkaline slag.

PubMed

Li, Jiu-yu; Masud, M M; Li, Zhong-yi; Xu, Ren-kou

2015-07-01

The acidity of Ultisols (pH <5) is detrimental to crop production. Technologies should be explored to promote base saturation and liming effect for amelioration of Ultisol pH. Column leaching experiments were conducted to investigate the amelioration effects of canola straw (CS) and peanut straw (PS) in single treatment and in combination whether with alkaline slag (AS) or with lime on Ultisol profile acidity. The treatment without liming materials was set as control, and the AS and lime in single treatment are set for comparison. Results indicated that all the liming materials increase soil profile pH and soil exchangeable base cations at the 0-40-cm depth, except that the lime had amelioration effect just on 0 to 15-cm profile. The amelioration effect of the liming materials on surface soil acidity was mainly dependent on the ash alkalinity in organic materials or acid neutralization capacity of inorganic materials. Specific adsorption of sulfate (SO4(2-)) or organic anions, decarboxylation of organic acids/anions, and the association of H(+) with organic anions induced a "liming effect" of crop residues and AS on subsoil acidity. Moreover, SO4(2-) and chloride (Cl(-)) in PS, CS, and AS primarily induced base cations to move downward to subsoil and exchange with exchangeable aluminum (Al(3+)) and protons (H(+)). These anions also promoted the exchangeable Al to leach out of the soil profile. The CS was more effective than PS in decreasing soil acidity in the subsoil, which mainly resulted from higher sulfur (S) and Cl content in CS compared to PS. The CS combined with AS was the better amendment choice in practical agricultural systems.

Identification of residues of sulfosulfuron and its metabolites in subsoil-dissipation kinetics and factors influencing the stability and degradation of residues from topsoil to subsoil under predominant cropping conditions.

PubMed

Atmakuru, Ramesh; Perumal Elumalai, Thirugnanam; Sivanandam, Sathiyanarayanan

2007-07-01

Long term stability of sulfosulfuron was investigated in subsoil under the natural wheat cropping conditions. Experiments were conducted by applying a commercial formulation of sulfosulfuron on soil at 50 g/ha and 100 g/ha. To understand the factors influencing the persistence of residues two different experiments were conducted. In one experiment wheat crop was cultivated once at the beginning of the two years study period and subsequently the plots were kept undisturbed for the remaining period. In another experiment cultivation of subsequent crops were continued during the study period. In both the cases sulfosulfuron was applied only once at the beginning of the study. Representative soil samples were collected from the depths viz., 0-5, 15, 30, 45, 60 and 90 cm on different pre determined sampling occasions 50, 100, 200, 300, 400, 500 and 600 days after the application of the herbicide. The collected soil samples were analyzed for the residues of sulfosulfuron. Under the influence of continuous cropping conditions residues of sulfosulfuron were found to be relatively low when compared with the soil samples collected from the agriculture plots maintained without any cultivation. The residues detected are in the range 0.001 to 0.017 microg/g. Samples collected from the depth, at 30 to 45 cm showed higher residual concentrations. Soil samples were also showed the presence of break down products. The data has been confirmed by LC-MS/MS. The relation between residue content of sulfosulfuron and the factors contributing the stability of herbicide concentration were also studied.

Chemical characterization of iron-mediated soil organic matter stabilization in tropical subsoils

NASA Astrophysics Data System (ADS)

Coward, E.; Plante, A. F.; Thompson, A.

2015-12-01

Tropical forest soils contribute disproportionately to the poorly-characterized and persistent deep soil carbon (C) pool. Highly-weathered and often extending one to two meters deep, these soils also contain an abundance of semicrystalline, Fe- and Al-containing short-range-order (SRO) minerals, metastable derivatives of framework silicate and ferromagnesian parent materials. SRO minerals are capable of soil organic matter (SOM) stabilization through sorption or co-precipitation, a faculty enhanced by their high specific surface area (SSA). As such, SRO-mediated organomineral associations may prove a critical, yet matrix-selective, driver of SOM stabilization capacity in tropical soils, particularly at depth. Surface (0-20 cm) and subsoil (50-80 cm) samples were taken from 20 quantitative soil pits dug in the Luquillo Critical Zone Observatory, located in northeast Puerto Rico. Soils were stratified across granodiorite and volcaniclastic parent materials, spanning primary mineral contents of 5 to 40%. Selective dissolution procedures were used to isolate distinct forms of Fe-C interactions: (1) sodium pyrophosphate to isolate organo-mineral complexes, (2) hydroxylamine and (3) oxalate to isolate SRO phases, and (4) inorganic dithionite to isolate crystalline Fe oxides. Extracts were analysed for dissolved organic C (DOC) and Fe and Al concentrations to estimate SOM associated with each mineral phase. Soils were also subjected to SSA analysis, 57Fe-Mössbauer spectroscopy and X-ray diffraction before and after extraction to determine the contribution of extracted mineral phases to SOM stabilization capacity. Preliminary results indicate a dominance of secondary (hydr)oxides and kaolin minerals in surface soils, strongly driven by parent material. With depth, however, we observe a marked shift towards SRO mineral phases across both parent materials, suggesting that SRO-mediated organomineral associations are significant contributors to observed C storage in tropical subsoils.

Comparison of soil organic carbon speciation using C NEXAFS and CPMAS 13C NMR spectroscopy.

PubMed

Prietzel, Jörg; Müller, Svenja; Kögel-Knabner, Ingrid; Thieme, Jürgen; Jaye, Cherno; Fischer, Daniel

2018-07-01

We compared synchrotron-based C near-edge X-ray absorption fine structure (NEXAFS) and CPMAS 13 C nuclear magnetic resonance (NMR) spectroscopy with respect to their precision and accuracy to quantify different organic carbon (OC) species in defined mixtures of soil organic matter source compounds. We also used both methods to quantify different OC species in organic surface horizons of a Histic Leptosol as well as in mineral topsoil and subsoil horizons of two soils with different parent material, stage of pedogenesis, and OC content (Cambisol: 15-30 OC mgg -1 , Podzol: 0.9-7 OC mgg -1 ). CPMAS 13 C NMR spectroscopy was more accurate and precise (mean recovery of different C functional groups 96-103%) than C NEXAFS spectroscopy (mean recovery 92-113%). For organic surface and topsoil samples, NMR spectroscopy consistently yielded larger O-alkyl C percentages and smaller alkyl C percentages than C NEXAFS spectroscopy. For the Cambisol subsoil samples both methods performed well and showed similar C speciation results. NEXAFS spectroscopy yielded excellent spectra with a high signal-to-noise ratio also for OC-poor Podzol subsoil samples, whereas this was not the case for CPMAS 13 C NMR spectroscopy even after sample treatment with HF. Our results confirm the analytical power of CPMAS 13 C NMR spectroscopy for a reliable quantitative OC speciation in soils with >10mgOCg -1 . Moreover, they highlight the potential of synchrotron-based C NEXAFS spectroscopy as fast, non-invasive method to semi-quantify different C functional groups in soils with low C content (0.9-10mgg -1 ). Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Nitrogen Fertilization and Thinning Treatments on Subsurface Soil Carbon and Nitrogen

NASA Astrophysics Data System (ADS)

Gross, C. D.; James, J. N.; Harrison, R. B.

2016-12-01

Increases in intensively managed forest plantations have caused concern for the long-term productivity and sustainability of these stands, as decreased organic matter retention and shorter rotations can substantially impact soil nutrition both in the short- and long-term. This study aims to provide data for regional responses of soil carbon (C) and nitrogen (N) by depth to fertilization and thinning treatments. Soil was sampled at an intensively managed Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation in northwestern Oregon, USA. Nine 0.2-ha plots were sampled with at least three pits per plot. Management regimes included no treatment (control), fertilization (F+), minimal thinning (mT), repeated thinning (rT), and combination treatments (mTF+ and rTF+). Fertilized plots received a total of 1120 kg N ha-1 as urea over 16 years. Bulk density and chemical analysis samples were taken in the middle of succeeding soil layers at depths of 0.1, 0.2, 0.5, 1.0, and 1.5 m. Forest floor samples were collected from a randomly placed quadrat. Preliminary results show an increase in total soil C and N of 113 and 106%, respectively, on the mTF+ plot compared to a control plot. The subsoil, defined here as below 0.2 m, contained over 50% of both soil C and N on the mTF+ plot and experienced greater C and N increases than the surface soil following treatment. This study demonstrates that forest management practices over a relatively short time span (<30 years) can significantly alter subsoil, which comprises a substantial portion of biologically available C and N in terrestrial ecosystems. Subsoil processes are critical to our understanding of changes in soil quality and our ability to accurately assess changes in soil C and N reservoirs.

[Effect of tillage patterns on the structure of weed communities in oat fields in the cold and arid region of North China].

PubMed

Zhang, Li; Zhang, Li; Wu, Dong-Xia; Zhang, Jun-Jun

2014-06-01

In order to clarify the effects of tillage patterns on farmland weed community structure and crop production characteristics, based on 10 years location experiment with no-tillage, subsoiling and conventional tillage in the cold and arid region of North China, and supplementary experiment of plowing after 10 years no-tillage and subsoiling, oat was planted in 2 soils under different tillage patterns, and field weed total density, dominant weed types, weed diversity index, field weed biomass and oats yield were measured. The results showed that the regional weed community was dominated by foxtail weed (Setaira viridis); the weed density under long-term no-tillage was 2.20-5.14 times of tillage at different growing stages of oat, but there were no significant differences between conditional tillage and plowing after long-term no-tillage and subsoiling. Field weed Shannon diversity indices were 0.429 and 0.531, respectively, for sandy chestnut soil and loamy meadow soil under no-tillage conditions, and field weed biomass values were 1.35 and 2.26 times of plowing treatment, while the oat biomass values were only 2807.4 kg x hm(-2) and 4053.9 kg x hm(-2), decreased by 22.3% and 46.2%, respectively. The results showed that the weed community characteristics were affected by both tillage patterns and soil types. Long-term no-tillage farmland in the cold and arid region of North China could promote the natural evolution of plant communities by keeping more perennial weeds, and the plowing pattern lowered the annual weed density, eliminated perennial weeds with shallow roots, and stimulated perennial weeds with deep roots.

50 CFR 300.151 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... laws and regulations that concern fishing for fishery resources over which Russia exercises sovereign... Russia means the seabed and subsoil of the submarine areas over which, consistent with international law, Russia exercises sovereign rights. Russian Economic Zone or Russian EZ means a zone of waters off the...

50 CFR 300.151 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... laws and regulations that concern fishing for fishery resources over which Russia exercises sovereign... Russia means the seabed and subsoil of the submarine areas over which, consistent with international law, Russia exercises sovereign rights. Russian Economic Zone or Russian EZ means a zone of waters off the...

50 CFR 300.151 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... laws and regulations that concern fishing for fishery resources over which Russia exercises sovereign... Russia means the seabed and subsoil of the submarine areas over which, consistent with international law, Russia exercises sovereign rights. Russian Economic Zone or Russian EZ means a zone of waters off the...

50 CFR 300.151 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... laws and regulations that concern fishing for fishery resources over which Russia exercises sovereign... Russia means the seabed and subsoil of the submarine areas over which, consistent with international law, Russia exercises sovereign rights. Russian Economic Zone or Russian EZ means a zone of waters off the...

19 CFR 10.502 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff treatment” means... its national laws and international law for the purpose of exploration and exploitation of the natural... States may exercise rights with respect to the seabed and subsoil and their natural resources; and (s...

19 CFR 10.502 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff treatment” means... its national laws and international law for the purpose of exploration and exploitation of the natural... States may exercise rights with respect to the seabed and subsoil and their natural resources; and (s...

19 CFR 10.502 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff treatment” means... its national laws and international law for the purpose of exploration and exploitation of the natural... States may exercise rights with respect to the seabed and subsoil and their natural resources; and (s...

19 CFR 10.502 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff treatment” means... its national laws and international law for the purpose of exploration and exploitation of the natural... States may exercise rights with respect to the seabed and subsoil and their natural resources; and (s...

19 CFR 10.502 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... natural person or an enterprise; (n) Preferential tariff treatment. “Preferential tariff treatment” means... its national laws and international law for the purpose of exploration and exploitation of the natural... States may exercise rights with respect to the seabed and subsoil and their natural resources; and (s...

The magnetic susceptibility of soils in Krakow, southern Poland

NASA Astrophysics Data System (ADS)

Wojas, Anna

2017-06-01

Studies into the magnetic susceptibility have been used to assess the soils contamination in the Krakow area. The results of topsoil (over a 2 × 2 km grid), subsoil (37 shallow holes) and soil samples (112) measurements were presented as maps of soil magnetic susceptibility (both volume and mass) illustrating the distribution of parameters in topsoil horizon (0-10 cm) and differential magnetic susceptibility maps between topsoil horizon and subsoil (40-60 cm). All evidence leads to the finding that the highest values of magnetic susceptibility of soil are found exclusively in industrial areas. Taking into consideration the type of land use, the high median value (89.8 × 10-8 m3kg-1) was obtained for samples of cultivated soils and is likely to be connected with occurrence of fertile soil (chernozem). Moreover, enrichment of soils with Pb and Zn accompanies magnetic susceptibility anomalies in the vicinity of the high roads and in the steelworks area, respectively.

Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes

NASA Astrophysics Data System (ADS)

Ekici, A.; Chadburn, S.; Chaudhary, N.; Hajdu, L. H.; Marmy, A.; Peng, S.; Boike, J.; Burke, E.; Friend, A. D.; Hauck, C.; Krinner, G.; Langer, M.; Miller, P. A.; Beer, C.

2015-07-01

Modeling soil thermal dynamics at high latitudes and altitudes requires representations of physical processes such as snow insulation, soil freezing and thawing and subsurface conditions like soil water/ice content and soil texture. We have compared six different land models: JSBACH, ORCHIDEE, JULES, COUP, HYBRID8 and LPJ-GUESS, at four different sites with distinct cold region landscape types, to identify the importance of physical processes in capturing observed temperature dynamics in soils. The sites include alpine, high Arctic, wet polygonal tundra and non-permafrost Arctic, thus showing how a range of models can represent distinct soil temperature regimes. For all sites, snow insulation is of major importance for estimating topsoil conditions. However, soil physics is essential for the subsoil temperature dynamics and thus the active layer thicknesses. This analysis shows that land models need more realistic surface processes, such as detailed snow dynamics and moss cover with changing thickness and wetness, along with better representations of subsoil thermal dynamics.

Uneven nutrient load and potential offsite loss

USDA-ARS?s Scientific Manuscript database

Landscape and management often results in uneven nutrient loads within a field. The hypotheses of this study are that: 1) phosphorus accumulates at low areas in the landscape adjacent to waterways; and 2) nitrate at lower landscape positions will be decreased in the subsoil due to denitrification an...

30 CFR 817.22 - Topsoil and subsoil.

Code of Federal Regulations, 2011 CFR

2011-07-01

...— (i) Occur at the site of small structures, such as power poles, signs, or fence lines; or (ii) Will... contaminants and unnecessary compaction that would interfere with revegetation; (iii) Be protected from wind... disturbances will result from facilities such as support facilities and preparation plants and where...

30 CFR 816.22 - Topsoil and subsoil.

Code of Federal Regulations, 2011 CFR

2011-07-01

... site of small structures, such as power poles, signs, or fence lines; or (ii) Will not destroy the... unnecessary compaction that would interfere with revegetation; (iii) Be protected from wind and water erosion... from facilities such as support facilities and preparation plants and where stockpiling of materials...

30 CFR 817.22 - Topsoil and subsoil.

Code of Federal Regulations, 2010 CFR

2010-07-01

...— (i) Occur at the site of small structures, such as power poles, signs, or fence lines; or (ii) Will... contaminants and unnecessary compaction that would interfere with revegetation; (iii) Be protected from wind... disturbances will result from facilities such as support facilities and preparation plants and where...

30 CFR 816.22 - Topsoil and subsoil.

Code of Federal Regulations, 2010 CFR

2010-07-01

... site of small structures, such as power poles, signs, or fence lines; or (ii) Will not destroy the... unnecessary compaction that would interfere with revegetation; (iii) Be protected from wind and water erosion... from facilities such as support facilities and preparation plants and where stockpiling of materials...

Effects of Nitrogen Fixing Pre-Crops and Fertilizers on Physical and Chemical Properties Down the Soil Profile

NASA Astrophysics Data System (ADS)

Hobley, E.; Honermeier, B.; Don, A.; Gocke, M. I.; Amelung, W.; Kogel-Knabner, I.

2016-12-01

We investigated the effects of pre-crops with and without biological nitrogen fixation capacity (fava beans, clover mulch, fodder maize) and fertilization (no fertilizer, NPK fertilizer, PK fertilizer) on soil physico-chemical properties (bulk density, electrical conductivity, soil organic carbon (SOC) concentration and stocks, N concentration and stocks) and their depth distribution (down to 1 m) at a long-term field experiment set up in 1982 in Gießen, Germany. Fertilization had significant but small impacts on the soil chemical environment, most particularly the salt content of the soil, with PK fertilization increasing electrical conductivity throughout the soil profile. Similarly, fertilization resulted in a small reduction of soil pH throughout the entire soil profile. The soil was physically and chemically affected by the type of pre-crop. Plots with fava beans and maize had lower bulk densities in the subsoil than those with clover. Pre-crop type also significantly affected the depth distribution of both N and SOC. Specifically, clover pre-cropping led to an enrichment of N at the surface compared with fava beans and maize. SOC enrichment at the surface was also observed under clover, with the effect most pronounced under PK fertilization. Combined with the bulk density effects, this shift in N distribution resulted in significantly higher N stocks under clover than under fava beans. However, the total stocks of SOC were not affected by pre-crop or fertilizer regime. Our results indicate that humans influence C and N cycling and distribution in soils through the selection of pre-crops and that the influence of crop type is greater than that of fertilization regimes. Pre-cropping with clover, which is used as a mulch, leads to N enrichment in the topsoil, reducing the need for N fertilizer for the subsequent cereal crop. In contrast, the use of fava beans as a pre-crop does not lead to N enrichment. We believe this is due to the greater rooting depth of fava beans compared with clover, resulting in lower bulk density in the subsoil and associated lower stocks. Additionally, the harvest of fava beans removes N-rich biomass from the soil, lowering N-input. Lastly, the uptake of water at depth may facilitate subsoil N uptake, so that fava bean N is utilized by the cereal crop but does not lead to its enrichment in the subsoil.

A 3D Resistivity Model of the Pyramid of La Luna (Teotihuacan, Mexico) Subsoil by Employing Non-Conventional ERT Arrays

NASA Astrophysics Data System (ADS)

Chavez, R. E.; Tejero, A.; Cifuentes, G.; Garcia-Serrano, A.; Argote-Espino, D. L.; HernaNdez-Quintero, J. E.; Ortega, V.

2017-12-01

The Pyramid of La Luna is found within the archaeological site of Teotihuacan, located to the NE of Mexico City. This pre-Hispanic city was developed between 250 AD and 450 AD, with a population of 100,000 people. The most important edifices are the pyramids of El Sol and La Luna. The pyramid of El Sol is one of the largest pre-Hispanic structures found nowadays in Mexico (a square basement of approximately 200m X 225 m). The pyramid of La Luna (with a base of 140m X 150m), smaller in size is located towards the northern portion of this ancient city. At its front, a big plaza is found surrounded by pyramids of different ages. Previous archaeological studies carried out within the plaza, discovered small shallow pipes for water discharge. Then, it is possible to find deeper structures within the Square. A geophysical work was carried out in the Plaza of La Luna employing the ERT-3D to build a 3D resistivity model. Four ERT profiles were deployed in the area in the E-W direction, with a length of 80 m each; electrodes were inserted 3 m apart. A roll-along technique was employed to obtain a 3D view of the plaza subsoil. Gradient (G), Equatorial (Eq), and Minimum Coupling (MC) arrays were applied. A total of 2,600 apparent resistivity observations were acquired. Also, the pyramid was surrounded with 105 electrodes to illuminate this structure subsoil, employing the 'L' and 'Corner' arrays and the already mentioned settings. Electrodes were separated 5 m for the E and N sides, and 6 m for the W and S sides, topographic correction was added to the interpretation. 7,200 apparent resistivity values were obtained. Processing of the data included noise filtering, real electrode position and removing of spikes. Finally, the data were inverted to compute a 3D resistivity distribution of the subsoil. Preliminary results obtained indicate the presence of high resistivity anomalies probably associated to infill or archaeological features. However, an interesting resistivity signature was determined at 8m deep, which possesses a SW-NE direction and apparently ends beneath the NE portion of the Pyramid of La Luna. Beneath the pyramid's center, the resistivity model interpreted depicts an important resistivity anomaly (about 350 Ohm-m and 10 m in diameter), which may indicate the presence of a cavity(?).

Effects of tractor loads and tyre pressures on soil compaction in Tunisia under different moisture conditions

NASA Astrophysics Data System (ADS)

Khemis, Chiheb; Abrougui, Khaoula; Ren, Lidong; Mutuku, Eunice Ann; Chehaibi, Sayed; Cornelis, Wim

2017-04-01

Vegetables in Tunisia demand frequent tractor traffic for soil tillage, cultural operations and phytosanitary treatment, resulting in soil compaction. This study evaluates the effects of four levels of compaction by using different loads and tyre pressures of tractors, i.e., load 1 (C1) = 1460 kg, load 2 (C2) = 3100 kg, tyre pressure 1 (C3) = 800 kg cm-2, tyre pressure 2 (C4) = 1500 kg cm-2 on the hydraulic and physical properties of a sandy loam (10% clay, 20% silt, 68% sand) under three natural moisture conditions H0, H1 (15 days later), H2 (30 days later). At H0 average water content between 0 and 30 cm depth varied from 0.04 to 0.06 kg kg-1, at H1 between 0.13 and 0.07 kg kg-1, and at H2 between 0.10 and 0.09 kg kg-1. Each test run was limited to one pass. Undisturbed soil cores were collected in the topsoil (0-10 cm), at 10-20 cm and in the subsoil (20-30 cm) below the trace of the wheel at sites in the Higher Institute of Agronomy of Chott Mariam, Sousse, Tunisia. Soil compaction level was determined by penetration resistance using a penetrologger. Porosity, bulk density and permeability were then determined to evaluate the impact of the four load/tyre pressure combinations at the three moisture conditions on soil compaction. Prior to the experiment (C0), bulk density was 1.4 Mg m-3. After the tractor pass, the highest degree of compaction was observed with tractor load C2 and tyre pressure C4 which significantly changed soil bulk density resulting in values of up to 1.71 Mg m-3 in the topsoil and compacted subsoil under H2, which is significantly above the critical value of 1.6 Mg m-3 for soils with clay content below 17.5%. The high degree of compaction significantly affected penetration resistance and porosity of both topsoil and subsoil layers accordingly. Permeability was significantly reduced as a result of the induced compaction. The results demonstrate that different degrees of soil compaction under different moisture levels could greatly influence hydraulic and physical properties in different ways. Even under relatively low water contents, i.e., below or near field capacity, substantial top and subsoil compaction was induced after one tractor pass.

Carbon and 14C distribution in tropical and subtropical agricultural soils

NASA Astrophysics Data System (ADS)

Prastowo, Erwin; Grootes, Pieter; Nadeau, Marie

2016-04-01

Paddy soil management affects, through the alternating anoxic and oxic conditions it creates, the transport and stabilisation of soil organic matter (SOM). Irrigation water may percolate more organic materials - dissolved (DOM) and colloidal - into the subsoil during anoxic conditions. Yet a developed ploughpan tends to prevent C from going deeper in the subsoil and partly decouple C distribution in top and sub soil. We investigate the influence of different soil type and environment. We observed the C and 14C distribution in paddy and non-paddy soil profiles in three different soil types from four different climatic regions of tropical Indonesia, and subtropical China. Locations were Sukabumi (Andosol, ca. 850 m a.s.l), Bogor (clayey Alisol, ca. 240 m a.s.l), and Ngawi (Vertisol, ca. 70 m a.s.l) in Jawa, Indonesia, and Cixi (Alisol(sandy), ca. 4 - 6 m a.s.l) in Zhejiang Province, China. We compared rice paddies with selected neighbouring non-paddy fields and employed AMS 14C as a tool to study C dynamics from bulk, alkali soluble-humic, and insoluble humin samples, and macrofossils (plant remains, charcoal). Our data suggest that vegetation type determines the quantity and quality of biomass introduced as litter and root material in top and subsoil, and thus contributes to the soil C content and profile, which fits the 14C signal distribution, as well as 13C in Ngawi with C4 sugar cane as upland crop. 14C concentrations for the mobile humic acid fraction were generally higher than for bulk samples from the same depth, except when recent plant and root debris led to high 14C levels in near-surface samples. The difference in sampling, - averaged layer for bulk sample and 1-cm layer thickness for point sample - shows gradients in C and 14C across the layers, which could be a reason for discrepancies between the two. High 14C concentrations - in Andosol Sukabumi up to 111 pMC - exceed the atmospheric 14CO2concentration in the sampling year in 2012 (˜ 103 pMC) and reflect stored organic material from earlier years with a higher atmospheric bomb 14C content. Direct inputs of plant material into the subsoil is indicated by young organic remains with more than 103 pMC below 0.8 m depth. In combination with 13C observation, it is quite obvious that introduction of young C took place in both paddy and non-paddy.

Long term soil pH change in rainfed cropping systems: is acidification systemic?

USDA-ARS?s Scientific Manuscript database

Many soils throughout the northern Great Plains developed from deep, moderately-weathered glacial and loess deposits under prairie vegetation. Soils of this type are typically neutral to slightly acidic in near-surface depths, and slightly to strongly alkaline in subsoil depths, with high buffer cap...

7 CFR 330.100 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., DEPARTMENT OF AGRICULTURE FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY... composing part of the surface of the globe, in distinction from the firm rock, and including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Garbage...

7 CFR 330.100 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., DEPARTMENT OF AGRICULTURE FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY... composing part of the surface of the globe, in distinction from the firm rock, and including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Garbage...

7 CFR 330.100 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., DEPARTMENT OF AGRICULTURE FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY... composing part of the surface of the globe, in distinction from the firm rock, and including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Garbage...

7 CFR 330.100 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., DEPARTMENT OF AGRICULTURE FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY... composing part of the surface of the globe, in distinction from the firm rock, and including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Garbage...

7 CFR 330.100 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., DEPARTMENT OF AGRICULTURE FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY... composing part of the surface of the globe, in distinction from the firm rock, and including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Garbage...

THE AFFORDABLE BIOSHELTERS PROJECT: TESTING INNOVATIVE TECHNOLOGIES, WORKING TO MAKE HIGH PERFORMANCE SOLAR GREENHOUSES COST COMPETITIVE

EPA Science Inventory

The economic feasibility and limitations of technologies investigated will be evaluated, including for liquid foam insulation, subsoil heat storages, and compost exhaust heating. These systems will save most of the energy and money spent to heat greenhouses in exchange for a h...

Topsoil thickness effects on phosphorus and potassium dynamics on claypan soils

USDA-ARS?s Scientific Manuscript database

Due to variable depth to claypan (DTC) across landscapes, nutrient supply from subsoils, and crop removal, precise P and K fertilizer management on claypan soil fields can be difficult. Therefore, a study was performed to determine if DTC derived from soil apparent electrical conductivity (ECa) coul...

Soil nutrient variability and groundwater nitrate-N in agricultural fields

USDA-ARS?s Scientific Manuscript database

Landscape and management often result in uneven nutrient loads within a field. The hypotheses of this study are that 1) phosphorus accumulates at low areas in the landscape adjacent to waterways, and 2) nitrate at lower landscape positions will be decreased in the subsoil due to denitrification and ...

Standard Penetration Test and Relative Density

DTIC Science & Technology

1971-02-01

Se OPSeS Debido a que el agua subterranea granclemente influve la resistencia a suelo, se establecio una relacion empirica entre el nurmero de golpes...de laboratorio ejecutados con un penetr6metro est’tico pequeno. INTRODUCTION One of the main problems encountered in subsoil e’xploration is in situ

Long term stability of microbial diversity and activity potential in severely disturbed arid lands of the southwest

USDA-ARS?s Scientific Manuscript database

Arid land cryptobiotic soil crusts govern water infiltration, soil aggregate stability and nutrient cycling between soil microbial communities and vascular plants. Surface mining involves removal of topsoil and associated crust and storage in mixed mounds for extended periods. The exposed subsoil an...

Radar Cuts Subsoil Survey Costs

NASA Technical Reports Server (NTRS)

Johnson, R.; Glaccum, R.

1984-01-01

Soil features located with minimum time and labor. Ground-penetrating radar (GPR) system supplements manual and mechanical methods in performing subsurface soil survey. Mobile system obtains graphic profile of soil discontinuities and interfaces as function of depth. One or two test borings necessary to substantiate soil profile. GPR proves useful as reconnaissance tool.

7 CFR 319.37-1 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Europe. The continent of Europe, the British Isles, Iceland, the Azores, and the... authority to act in his/her stead has been or may hereafter be delegated. Soil. The loose surface material...

7 CFR 319.37-1 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the globe, in distinction from the firm rock, and including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Europe. The continent of Europe... stead has been or may hereafter be delegated. Soil. The loose surface material of the earth in which...

7 CFR 319.37-1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... including the soil and subsoil, as well as finely divided rock and other soil formation materials down to the rock layer. Europe. The continent of Europe, the British Isles, Iceland, the Azores, and the... authority to act in his/her stead has been or may hereafter be delegated. Soil. The loose surface material...

19 CFR 10.402 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Republic of Chile; (r) Person. “Person” means a natural person or an enterprise; (s) Preferential tariff... subsoil and their natural resources; (x) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. [CBP Dec. 05-07, 70 FR 10873, Mar. 7, 2005, as...

19 CFR 10.582 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization... the United States and that country; (p) Person. “Person” means a natural person or an enterprise; (q...

19 CFR 10.582 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization... the United States and that country; (p) Person. “Person” means a natural person or an enterprise; (q...

19 CFR 10.402 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Republic of Chile; (r) Person. “Person” means a natural person or an enterprise; (s) Preferential tariff... subsoil and their natural resources; (x) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. [CBP Dec. 05-07, 70 FR 10873, Mar. 7, 2005, as...

19 CFR 10.402 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Republic of Chile; (r) Person. “Person” means a natural person or an enterprise; (s) Preferential tariff... subsoil and their natural resources; (x) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. [CBP Dec. 05-07, 70 FR 10873, Mar. 7, 2005, as...

19 CFR 10.582 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization... the United States and that country; (p) Person. “Person” means a natural person or an enterprise; (q...

19 CFR 10.1002 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... respect to the seabed and subsoil and their natural resources; (x) WTO. “WTO” means the World Trade Organization; and (y) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade... Republic of Korea; (r) Person. “Person” means a natural person or an enterprise; (s) Person of a Party...

19 CFR 10.582 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization... the United States and that country; (p) Person. “Person” means a natural person or an enterprise; (q...

19 CFR 10.3002 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

.... “Party” means the United States or Colombia; (q) Person. “Person” means a natural person or an enterprise..., the United States may exercise rights with respect to the seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means...

19 CFR 10.1002 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... respect to the seabed and subsoil and their natural resources; (x) WTO. “WTO” means the World Trade Organization; and (y) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade... Republic of Korea; (r) Person. “Person” means a natural person or an enterprise; (s) Person of a Party...

19 CFR 10.402 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Republic of Chile; (r) Person. “Person” means a natural person or an enterprise; (s) Preferential tariff... subsoil and their natural resources; (x) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. [CBP Dec. 05-07, 70 FR 10873, Mar. 7, 2005, as...

19 CFR 10.1002 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... respect to the seabed and subsoil and their natural resources; (x) WTO. “WTO” means the World Trade Organization; and (y) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade... Republic of Korea; (r) Person. “Person” means a natural person or an enterprise; (s) Person of a Party...

19 CFR 10.402 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Republic of Chile; (r) Person. “Person” means a natural person or an enterprise; (s) Preferential tariff... subsoil and their natural resources; (x) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization of April 15, 1994. [CBP Dec. 05-07, 70 FR 10873, Mar. 7, 2005, as...

19 CFR 10.3002 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

.... “Party” means the United States or Colombia; (q) Person. “Person” means a natural person or an enterprise..., the United States may exercise rights with respect to the seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means...

19 CFR 10.582 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... seabed and subsoil and their natural resources; (v) WTO. “WTO” means the World Trade Organization; and (w) WTO Agreement. “WTO Agreement” means the Marrakesh Agreement Establishing the World Trade Organization... the United States and that country; (p) Person. “Person” means a natural person or an enterprise; (q...

78 FR 69118 - Information Collection Activities: General; Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-18

... human, marine, and coastal environments; to ensure the public a fair and equitable return on the... ``operations in the [O]uter Continental Shelf should be conducted in a safe manner by well trained personnel... subsoil and seabed, or other occurrences which may cause damage to the environment or to property or...

40 CFR 265.310 - Closure and post-closure care.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Closure and post-closure care. 265.310... DISPOSAL FACILITIES Landfills § 265.310 Closure and post-closure care. (a) At final closure of the landfill... subsoils present. (b) After final closure, the owner or operator must comply with all post-closure...

40 CFR 265.310 - Closure and post-closure care.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Closure and post-closure care. 265.310... DISPOSAL FACILITIES Landfills § 265.310 Closure and post-closure care. (a) At final closure of the landfill... subsoils present. (b) After final closure, the owner or operator must comply with all post-closure...

40 CFR 265.310 - Closure and post-closure care.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Closure and post-closure care. 265.310... DISPOSAL FACILITIES Landfills § 265.310 Closure and post-closure care. (a) At final closure of the landfill... subsoils present. (b) After final closure, the owner or operator must comply with all post-closure...

Runoff processes in catchments with a small scale topography

NASA Astrophysics Data System (ADS)

Feyen, H.; Leuenberger, J.; Papritz, A.; Gysi, M.; Flühler, H.; Schleppi, P.

1996-05-01

How do runoff processes influence nitrogen export from forested catchments? To support nitrogen balance studies for three experimental catchments (1500m 2) in the Northern Swiss prealps water flow processes in the two dominating soil types are monitored. Here we present the results for an experimental wetland catchment (1500m 2) and for a delineated sloped soil plot (10m 2), both with a muck humus topsoil. Runoff measurements on both the catchment and the soil plot showed fast reactions of surface and subsurface runoff to rainfall inputs, indicating the dominance of fast-flow paths such as cracks and fissures. Three quarters of the runoff from the soil plot can be attributed to water flow in the gleyic, clayey subsoil, 20% to flow in the humic A horizon and only 5% to surface runoff. The water balance for the wetland catchment was closed. The water balance of the soil plot did not close. Due to vertical upward flow from the saturated subsoil into the upper layers, the surface runoff plus subsurface runoff exceeded the input (precipitation) to the plot.

The role of local heterogeneity in transport through steep hillslopes.

NASA Astrophysics Data System (ADS)

Fiori, A.; Russo, D.

2009-04-01

A stochastic model is developed for the analysis of the travel time distribution in a hillslope. The latter is represented as a system made up from a highly permeable soil underlain by a less permeable subsoil or bedrock. The heterogeneous hydraulic conductivity K is described as a stationary random space function. The travel time distribution is obtained through a stochastic Lagrangian model of transport, after adopting a first order approximation in the logconductivity variance. The results show that the travel time pdf pertaining to the soil is power-law, with exponent variable between -1 and -0.5; the behavior is mainly determined by unsaturated transport. The subsoil is mainly responsible for the tail of the travel time distribution. Analysis of the first and second moments of travel time show that the spreading of solute is controlled by the variations in the flow-paths (geomorphological dispersion), which depend on the hillslope geometry. Conversely, the contribution of the K heterogeneity to spreading appears as less relevant. The model is tested against a detailed three-dimensional numerical simulation with reasonably good agreement.

Time-lapse 3D electrical resistivity tomography to monitor soil-plant interactions

NASA Astrophysics Data System (ADS)

Boaga, Jacopo; Rossi, Matteo; Cassiani, Giorgio; Putti, Mario

2013-04-01

In this work we present the application of time-lapse non-invasive 3D micro- electrical tomography (ERT) to monitor soil-plant interactions in the root zone in the framework of the FP7 Project CLIMB (Climate Induced Changes on the Hydrology of Mediterranean Basins). The goal of the study is to gain a better understanding of the soil-vegetation interactions by the use of non-invasive techniques. We designed, built and installed a 3D electrical tomography apparatus for the monitoring of the root zone of a single apple tree in an orchard located in the Trentino region, Northern Italy. The micro-ERT apparatus consists of 48 buried electrodes on 4 instrumented micro boreholes plus 24 mini-electrodes on the surface spaced 0.1 m on a square grid. We collected repeated ERT and TDR soil moisture measurements for one year and performed two different controlled irrigation tests: one during a very dry Summer and one during a very wet and highly dynamic plant growing Spring period. We also ran laboratory analyses on soil specimens, in order to evaluate the electrical response at different saturation steps. The results demonstrate that 3D micro-ERT is capable of characterizing subsoil conditions and monitoring root zone activities, especially in terms of root zone suction regions. In particular, we note that in very dry conditions, 3D micro ERT can image water plumes in the shallow subsoil produced by a drip irrigation system. In the very dynamic growing season, under abundant irrigation, micro 3D ERT can detect the main suction zones caused by the tree root activity. Even though the quantitative use of this technique for moisture content balance suffers from well-known inversion difficulties, even the pure imaging of the active root zone is a valuable contribution. However the integration of the measurements in a fully coupled hydrogeophysical inversion is the way forward for a better understanding of subsoil interactions between biomass, hydrosphere and atmosphere.

Changes in microbial structure and functional communities at different soil depths during 13C labelled root litter degradation

NASA Astrophysics Data System (ADS)

Sanaullah, Muhammad; Baumann, Karen; Chabbi, Abad; Dignac, Marie-France; Maron, Pierre-Alain; Kuzyakov, Yakov; Rumpel, Cornelia

2014-05-01

Soil organic matter turnover depends on substrate quality and microbial activity in soil but little is known about how addition of freshly added organic material modifies the diversity of soil microbial communities with in a soil profile. We took advantage of a decomposition experiment, which was carried out at different soil depths under field conditions and sampled litterbags with 13C-labelled wheat roots, incubated in subsoil horizons at 30, 60 and 90 cm depth for up to 36 months. The effect of root litter addition on microbial community structure, diversity and activity was studied by determining total microbial biomass, PLFA signatures, molecular tools (DNA genotyping and pyrosequencing of 16S and 18S rDNAs) and extracellular enzyme activities. Automated ribosomal intergenic spacer analysis (ARISA) was also carried out to determine the differences in microbial community structure. We found that with the addition of root litter, total microbial biomass as well as microbial community composition and structure changed at different soil depths and change was significantly higher at top 30cm soil layer. Moreover, in the topsoil, population of both gram-positive and gram-negative bacteria increased with root litter addition over time, while subsoil horizons were relatively dominated by fungal community. Extra-cellular enzyme activities confirmed relatively higher fungal community at subsoil horizons compared with surface soil layer with bacteria dominant microbial population. Bacterial-ARISA profiling illustrated that the addition of root litter enhanced the abundance of Actinobacteria and Proteobacteria, at all three soil depths. These bacteria correspond to copiotrophic attributes, which can preferentially consume of labile soil organic C pools. While disappearance of oligotrophic Acidobacteria confirmed the shifting of microbial communities due to the addition of readily available substrate. We concluded that root litter mixing altered microbial community development which was soil horizon specific and its effects on soil microbial activity may impact on nutrient cycling.

Effects of Management on Soil Carbon Pools in California Rangeland Ecosystems

NASA Astrophysics Data System (ADS)

Silver, W. L.; Ryals, R.; Lewis, D. J.; Creque, J.; Wacker, M.; Larson, S.

2008-12-01

Rangeland ecosystems managed for livestock production represent the largest land-use footprint globally, covering more than one-quarter of the world's land surface (Asner et al. 2004). In California, rangelands cover an estimated 17 million hectares or approximately 40% of the land area (FRAP 2003). These ecosystems have considerable potential to sequester carbon (C) in soil and offset greenhouse gas emissions through changes in land management practices. Climate policies and C markets may provide incentives for rangeland managers to pursue strategies that optimize soil C storage, yet we lack a thorough understanding of the effects of management on soil C pools in rangelands over time and space. We sampled soil C pools on rangelands in a 260 km2 region of Marin and Sonoma counties to determine if patterns in soil C storage exist with management. Replicate soil samples were collected from 35 fields that spanned the dominant soil orders, plant communities, and management practices in the region while controlling for slope and bioclimatic zone (n = 1050). Management practices included organic amendments, intensive (dairy) and extensive (other) grazing practices, and subsoiling. Soil C pools ranged from approximately 50 to 140 Mg C ha-1 to 1 m depth, with a mean of 99 ± 22 (sd) Mg C ha-1. Differences among sites were due primarily to C concentrations, which exhibited a much larger coefficient of variation than bulk density at all depths. There were no statistically significant differences among the dominant soil orders. Subsoiling appeared to significantly increase soil C content in the top 50 cm, even though subsoiling had only occurred for the first time the previous Nov. Organic amendments also appeared to greatly increase soil C pools, and was the dominant factor that distinguished soil C pools in intensive and extensive land uses. Our results indicate that management has the potential to significantly increase soil C pools. Future research will determine the location of sequestered C within the soil matrix and its turnover time.

A comparison between the example reference biosphere model ERB 2B and a process-based model: simulation of a natural release scenario.

PubMed

Almahayni, T

2014-12-01

The BIOMASS methodology was developed with the objective of constructing defensible assessment biospheres for assessing potential radiological impacts of radioactive waste repositories. To this end, a set of Example Reference Biospheres were developed to demonstrate the use of the methodology and to provide an international point of reference. In this paper, the performance of the Example Reference Biosphere model ERB 2B associated with the natural release scenario, discharge of contaminated groundwater to the surface environment, was evaluated by comparing its long-term projections of radionuclide dynamics and distribution in a soil-plant system to those of a process-based, transient advection-dispersion model (AD). The models were parametrised with data characteristic of a typical rainfed winter wheat crop grown on a sandy loam soil under temperate climate conditions. Three safety-relevant radionuclides, (99)Tc, (129)I and (237)Np with different degree of sorption were selected for the study. Although the models were driven by the same hydraulic (soil moisture content and water fluxes) and radiological (Kds) input data, their projections were remarkably different. On one hand, both models were able to capture short and long-term variation in activity concentration in the subsoil compartment. On the other hand, the Reference Biosphere model did not project any radionuclide accumulation in the topsoil and crop compartments. This behaviour would underestimate the radiological exposure under natural release scenarios. The results highlight the potential role deep roots play in soil-to-plant transfer under a natural release scenario where radionuclides are released into the subsoil. When considering the relative activity and root depth profiles within the soil column, much of the radioactivity was taken up into the crop from the subsoil compartment. Further improvements were suggested to address the limitations of the Reference Biosphere model presented in this paper. Copyright © 2014 Elsevier Ltd. All rights reserved.

Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?

PubMed

Laceby, J Patrick; Huon, Sylvain; Onda, Yuichi; Vaury, Veronique; Evrard, Olivier

2016-12-01

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted in radiocesium fallout contaminating coastal catchments of the Fukushima Prefecture. As the decontamination effort progresses, the potential downstream migration of radiocesium contaminated particulate matter from forests, which cover over 65% of the most contaminated region, requires investigation. Carbon and nitrogen elemental concentrations and stable isotope ratios are thus used to model the relative contributions of forest, cultivated and subsoil sources to deposited particulate matter in three contaminated coastal catchments. Samples were taken from the main identified sources: cultivated (n = 28), forest (n = 46), and subsoils (n = 25). Deposited particulate matter (n = 82) was sampled during four fieldwork campaigns from November 2012 to November 2014. A distribution modelling approach quantified relative source contributions with multiple combinations of element parameters (carbon only, nitrogen only, and four parameters) for two particle size fractions (<63 μm and <2 mm). Although there was significant particle size enrichment for the particulate matter parameters, these differences only resulted in a 6% (SD 3%) mean difference in relative source contributions. Further, the three different modelling approaches only resulted in a 4% (SD 3%) difference between relative source contributions. For each particulate matter sample, six models (i.e. <63 μm and <2 mm from the three modelling approaches) were used to incorporate a broader definition of potential uncertainty into model results. Forest sources were modelled to contribute 17% (SD 10%) of particulate matter indicating they present a long term potential source of radiocesium contaminated material in fallout impacted catchments. Subsoils contributed 45% (SD 26%) of particulate matter and cultivated sources contributed 38% (SD 19%). The reservoir of radiocesium in forested landscapes in the Fukushima region represents a potential long-term source of particulate contaminated matter that will require diligent management for the foreseeable future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Farming system context drives the value of deep wheat roots in semi-arid environments

PubMed Central

Lilley, Julianne M.; Kirkegaard, John A.

2016-01-01

The capture of subsoil water by wheat roots can make a valuable contribution to grain yield on deep soils. More extensive root systems can capture more water, but leave the soil in a drier state, potentially limiting water availability to subsequent crops. To evaluate the importance of these legacy effects, a long-term simulation analysis at eight sites in the semi-arid environment of Australia compared the yield of standard wheat cultivars with cultivars that were (i) modified to have root systems which extract more water at depth and/or (ii) sown earlier to increase the duration of the vegetative period and hence rooting depth. We compared simulations with and without annual resetting of soil water to investigate the legacy effects of drier subsoils related to modified root systems. Simulated mean yield benefits from modified root systems declined from 0.1–0.6 t ha−1 when annually reset, to 0–0.2 t ha−1 in the continuous simulation due to a legacy of drier soils (mean 0–32mm) at subsequent crop sowing. For continuous simulations, predicted yield benefits of >0.2 t ha−1 from more extensive root systems were rare (3–10% of years) at sites with shallow soils (<1.0 m), but occurred in 14–44% of years at sites with deeper soils (1.6–2.5 m). Earlier sowing had a larger impact than modified root systems on water uptake (14–31 vs 2–17mm) and mean yield increase (up to 0.7 vs 0–0.2 t ha−1) and the benefits occurred on deep and shallow soils and in more years (9–79 vs 3–44%). Increasing the proportion of crops in the sequence which dry the subsoil extensively has implications for the farming system productivity, and the crop sequence must be managed tactically to optimize overall system benefits. PMID:26976814

Farming system context drives the value of deep wheat roots in semi-arid environments.

PubMed

Lilley, Julianne M; Kirkegaard, John A

2016-06-01

The capture of subsoil water by wheat roots can make a valuable contribution to grain yield on deep soils. More extensive root systems can capture more water, but leave the soil in a drier state, potentially limiting water availability to subsequent crops. To evaluate the importance of these legacy effects, a long-term simulation analysis at eight sites in the semi-arid environment of Australia compared the yield of standard wheat cultivars with cultivars that were (i) modified to have root systems which extract more water at depth and/or (ii) sown earlier to increase the duration of the vegetative period and hence rooting depth. We compared simulations with and without annual resetting of soil water to investigate the legacy effects of drier subsoils related to modified root systems. Simulated mean yield benefits from modified root systems declined from 0.1-0.6 t ha(-1) when annually reset, to 0-0.2 t ha(-1) in the continuous simulation due to a legacy of drier soils (mean 0-32mm) at subsequent crop sowing. For continuous simulations, predicted yield benefits of >0.2 t ha(-1) from more extensive root systems were rare (3-10% of years) at sites with shallow soils (<1.0 m), but occurred in 14-44% of years at sites with deeper soils (1.6-2.5 m). Earlier sowing had a larger impact than modified root systems on water uptake (14-31 vs 2-17mm) and mean yield increase (up to 0.7 vs 0-0.2 t ha(-1)) and the benefits occurred on deep and shallow soils and in more years (9-79 vs 3-44%). Increasing the proportion of crops in the sequence which dry the subsoil extensively has implications for the farming system productivity, and the crop sequence must be managed tactically to optimize overall system benefits. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Phosphorus and other soil components in a dairy effluent sprayfield within the central Florida Ridge.

PubMed

Woodard, Kenneth R; Sollenberger, Lynn E; Sweat, Lewin A; Graetz, Donald A; Nair, Vimala D; Rymph, Stuart J; Walker, Leighton; Joo, Yongsung

2007-01-01

There is concern that P from dairy effluent sprayfields will leach into groundwater beneath Suwannee River basins in northern Florida. Our purpose was to describe the effects of dairy effluent irrigation on the movement of soil P and other nutrients within the upper soil profile of a sprayfield over three 12-mo cycles (April 1998-March 2001). Effluent P rates of 70, 110, and 165 kg ha(-1) cycle(-1) were applied to forages that were grown year-round. The soil is a deep, excessively drained sand (thermic, uncoated Typic Quartzipsamment). Mean P concentration in soil water below the rooting zone (152-cm depth) was < or = 0.1 mg L(-1) during 11 3-mo periods. Mehlich-1-extractable (M1) P, Al, and Ca in the topsoil increased over time but did not change in subsoil depths of 25 to 51, 51 to 71, 71 to 97, and 97 to 122 cm. Topsoil Ca increased as effluent rate increased. High Ca levels were found in dairy effluent (avg.: 305 mg L(-1)) and supplemental irrigation water (avg.: 145 mg L(-1)) which likely played a role in retaining P in the topsoil. An effect of effluent rate on P and Al concentrations in the topsoil was not detected, probably due to large and variable quantities present at project initiation. The P retention capacity (i.e., Al plus Fe) increased in the topsoil because Al increased. Dairy effluent contained Al (avg.: 31 mg L(-1)). Phosphorus saturation ratio (PSR) increased over time in the topsoil but not in subsoil layers. Regardless of effluent rate, the P retention capacity and PSR of subsoil, which contained 119 to 229 mg kg(-1) of Al, should be taken into account when assessing the risk of P moving below the rooting zone of most forage crops.

Differentiating the sources of fine sediment, organic matter and nitrogen in a subtropical Australian catchment.

PubMed

Garzon-Garcia, Alexandra; Laceby, J Patrick; Olley, Jon M; Bunn, Stuart E

2017-01-01

Understanding the sources of sediment, organic matter and nitrogen (N) transferred from terrestrial to aquatic environments is important for managing the deleterious off-site impacts of soil erosion. In particular, investigating the sources of organic matter associated with fine sediment may also provide insight into carbon (C) and N budgets. Accordingly, the main sources of fine sediment, organic matter (indicated by total organic carbon), and N are determined for three nested catchments (2.5km 2 , 75km 2 , and 3076km 2 ) in subtropical Australia. Source samples included subsoil and surface soil, along with C 3 and C 4 vegetation. All samples were analysed for stable isotopes (δ 13 C, δ 15 N) and elemental composition (TOC, TN). A stable isotope mixing model (SIAR) was used to determine relative source contributions for different spatial scales (nested catchments), climatic conditions and flow stages. Subsoil was the main source of fine sediment for all catchments (82%, SD=1.15) and the main N source at smaller scales (55-76%, SD=4.6-10.5), with an exception for the wet year and at the larger catchment, where surface soil was the dominant N source (55-61%, SD=3.6-9.9), though contributions were dependent on flow (59-680m 3 /s). C 3 litter was the main source of organic C export for the two larger catchments (53%, SD=3.8) even though C 4 grasses dominate the vegetation cover in these catchments. The sources of fine sediment, organic matter and N differ in subtropical catchments impacted by erosion, with the majority of C derived from C 3 leaf litter and the majority of N derived from either subsoil or surface soil. Understanding these differences will assist management in reducing sediment, organic matter and N transfers in similar subtropical catchments while providing a quantitative foundation for testing C and N budgets. Copyright © 2016 Elsevier B.V. All rights reserved.

Topographically-determined soil thickening explained spatial variability of soil carbon and nitrogen in Southern California grasslands

NASA Astrophysics Data System (ADS)

Lin, Y.; Prentice, S., III; Tran, T.; Bingham, N.; King, J. Y.; Chadwick, O.

2015-12-01

At the scale of hillslopes, topography strongly regulates soil formation, affecting hillslope hydrology and biological activities. Topographic control of soil formation is particularly strong for semi-arid landscapes where soil thickening is induced by pedoturbation and soil creep. Thus, terrain attributes hold great potential for modeling full profile soil C and N stocks at the hillslope scale in these landscapes. In this study, we developed predictions of grassland soil C and N stocks using digital terrain attributes scaled to the signal of site-specific hillslope geomorphic processes. We found that soil thickness was the major control of soil organic C and N stocks and was best predicted by mean curvature. This curvature dependency of soil thickness affected prediction of organic C and N stocks because of the C and N added by taking subsoil into account. We also found that curvature was positively correlated with depth to carbonate reflecting drier soil conditions in convex hillslope positions and wetter soil conditions in concave areas. Slope aspect also had a marginal effect on soil C and N stocks; soil organic C and N stocks on the north-facing slope tended to be higher than those on the south-facing slope. We found that terrain attributes at medium resolutions (8 to 16 m) were most effective in modeling soil C and N stocks. Overall, terrain attributes explained 61% of the variation in soil thickness and 49% of the variation in soil organic C stock. Our results suggest that curvature-induced soil thickening, coupled with aspect, likely exerts a first-order control on soil organic C and N accumulation rates, and these changes occur predominantly in subsoil. Thus our data highlight the importance of subsoil in mapping soil C and N stocks and other soil properties. Our model also demonstrates how scale-driven analysis may guide soil C and N prediction in other hillslope dominated regions.

Seismic Site Classification and Empirical Correlation Between Standard Penetration Test N Value and Shear Wave Velocity for Guwahati Based on Thorough Subsoil Investigation Data

NASA Astrophysics Data System (ADS)

Kumar, Abhishek; Harinarayan, N. H.; Verma, Vishal; Anand, Saurabh; Borah, Uddipana; Bania, Mousumi

2018-04-01

Guwahati, the Gateway of India in the northeast, is a large business and development center. Past seismic scenarios suggest moderate to significant effects of regional earthquakes (EQs) in Guwahati in terms of liquefaction as well as building damages. Considering the role of local soil in amplifying EQ-generated ground motions and controlling surface damages, present study attempts seismic site classification of subsoil of Guwahati. Subsoil is explored based on 43 geophysical tests and 244 borelogs gathered from different resources. Based on the borehole data, 4 numbers of 2D cross-sections are developed from different parts of Guwahati, clearly indicating that a majority of the locations are composed of clay of intermediate to high plasticity while at specific locations only, layers of sand are found at selective depths. Further, seismic site classification based on 30 m average SPT-N suggests that a major part of Guwahati falls under seismic site class (SSC) D such as Balaji Temple and Airport. However, Assam Zoo, Pan Bazaar, IIT campus, Dhol Gobinda and Maligaon show SSC E clearly indicating the presence of soft soil deposits at these locations. Similar site classification is also attempted from MASW test-based 30 m average shear wave velocity (V S30). V S30-based site classification also categorizes most of Guwahati under SSC D. However, there are locations in the southern part of Guwahati which belong to SSC C as well. Mismatch in SSC based on two different test findings for Indian soil found here are consistent with previous studies. Further, three empirical correlations based on both SPT-N and V S profiles at 22 test locations are developed for: (1) clayey; (2) sandy and (3) all soil types. Proposed correlation for all soil types is validated graphically and is found closely matching with similar correlations for Turkey and Lucknow.

Molybdate adsorption from steel slag eluates by subsoils.

PubMed

Matern, K; Rennert, T; Mansfeldt, T

2013-11-01

Steel slags are industrial by-products which are generated in large amounts worldwide, e.g. 150-230×10(6) Mg in 2012, and which are partly used for construction. Molybdenum (Mo) can be added during steel processing in order to harden the steel. The objective of this study was to evaluate the adsorption behaviour of molybdate (MoO4(2-)) from slag eluates in subsoils. Molybdate batch adsorption experiments were carried out with eluates obtained from two different kinds of steel slags (i) LD slag (Linz-Donawitz operation, LDS) and (ii) electric arc furnace slag (EAF) to assess the risk that may arise from the contamination of groundwater by the leaching of molybdate. Six different subsoils were chosen in order to provide a wide range of chemical properties (pH 4.0-7.6; dithionite-extractable Fe 0.73-14.7 g kg(-1)). Molybdate adsorption experiments were carried out at the pH of the steel slag eluates (pH 11-12) as well as at pH values adjusted to the soil pH. The data were evaluated with the Freundlich equation. Molybdate adsorption exhibited a maximum near pH 4 for steel slag eluates adjusted to the soil pH, and decreased rapidly with increasing pH until adsorption was virtually zero at pH>11. Adsorption was greater for soils with high amounts of dithionite-extractable Fe oxides. The extent and behaviour of molybdate adsorption from both eluates was similar. After a reaction time of 24h, the pH of the EAF slag eluate was lower than that of the LD steel slag eluate, which was caused by different acid buffer capacities. Some soils were able to decrease the pH of the EAF slag eluates by about 4 pH units, enhancing the adsorption of molybdate. Transport simulations indicated that molybdate discharge is low in acidic soils. Copyright © 2013 Elsevier Ltd. All rights reserved.

Spatial distribution of heterocyclic organic matter compounds at macropore surfaces in Bt-horizons

NASA Astrophysics Data System (ADS)

Leue, Martin; Eckhardt, Kai-Uwe; Gerke, Horst H.; Ellerbrock, Ruth H.; Leinweber, Peter

2017-04-01

The illuvial Bt-horizon of Luvisols is characterized by coatings of clay and organic matter (OM) at the surfaces of cracks, biopores and inter-aggregate spaces. The OM composition of the coatings that originate from preferential transport of suspended matter in macropores determines the physico-chemical properties of the macropore surfaces. The analysis of the spatial distribution of specific OM components such as heterocyclic N-compounds (NCOMP) and benzonitrile and naphthalene (BN+NA) could enlighten the effect of macropore coatings on the transport of colloids and reactive solutes during preferential flow and on OM turnover processes in subsoils. The objective was to characterize the mm-to-cm scale spatial distribution of NCOMP and BN+NA at intact macropore surfaces from the Bt-horizons of two Luvisols developed on loess and glacial till. In material manually separated from macropore surfaces the proportions of NCOMP and BN+NA were determined by pyrolysis-field ionization mass spectrometry (Py-FIMS). These OM compounds, likely originating from combustion residues, were found increased in crack coatings and pinhole fillings but decreased in biopore walls (worm burrows and root channels). The Py-FIMS data were correlated with signals from C=O and C=C groups and with signals from O-H groups of clay minerals as determined by Fourier transform infrared spectroscopy in diffuse reflectance mode (DRIFT). Intensive signals of C15 to C17 alkanes from long-chain alkenes as main components of diesel and diesel exhaust particulates substantiated the assumption that burning residues were prominent in the subsoil OM. The spatial distribution of NCOMP and BN+NA along the macropores was predicted by partial least squares regression (PLSR) using DRIFT mapping spectra from intact surfaces and was found closely related to the distribution of crack coatings and pinholes. The results emphasize the importance of clay coatings in the subsoil to OM sorption and stabilization. Differences between biopores and cracks suggest differences in the mass transport and OM turnover between these macropore types in Luvisols.

SEM and TEM Analyses of Minerals Xifengite, Gupeiite, Fe2Si (Hapkeite?), Titanium Carbide (TiC) and Cubic Moissanite (SiC) from the Subsoil in the Alpine Foreland: Are they Cosmochemical?

NASA Astrophysics Data System (ADS)

Hiltl, M.; Bauer, F.; Ernstson, K.; Mayer, W.; Neumair, A.; Rappenglück, M. A.

2011-03-01

SEM and TEM analyses of millimeter- to centimeter-sized particles from Holocene soils reveal a multi-stoichiometric iron silicide matrix containing purest crystals of titanium carbide and cubic moissanite. A cosmochemical origin is suggested.

Response of Competing Vegetation to Site Preparation on West Gulf Coastal Plain Commercial Forest Land

Treesearch

Gale L. Wolters; Henry A. Pearson; Ronald E. Thill; V. Clark Baldwin; Alton Martin

1995-01-01

The response of woody and herbaceous vegetation to site preparation, subsoil texture, and fertilization was measured on the West Gulf Coastal Plain. The influences of these treatments on competing vegetation were short-term. Drastic soil disturbance and fertilization briefly increased herbage production. Shear-windrow and shear-disk were generally the most effective...

Addition of phosphorus to subsoil promotes root development of yellow birch

Treesearch

Merrill C. Hoyle

1965-01-01

Pot-culture studies have indicated that roots of yellow birch (Betula alleghaniensis Britton) develop more prolifically in humus than in sandy mineral soil (Hoyle 1965; Winget et al. 1963; Redmond 1954; and Tubbs 1963). This situation has also been observed during root-excavation studies (Redmond 1957; Spaulding and MacAloney 1931). Results of these...

Middle Level Preservice Teachers Experience a Natural History Arts-Integrated Interdisciplinary Thematic Unit

ERIC Educational Resources Information Center

Weber, Carolyn A.; Rule, Audrey C.

2017-01-01

Curricular demands and best practices for middle school require interdisciplinary units. Arts integration can provide motivation and a new pathway to learning. This unit focused on inquiry into the natural history of artifacts and rocks recovered from the exposed subsoil of an area near Cedar Falls, Iowa that had been bulldozed as part of…

76 FR 38410 - BOEMRE Information Collection Activity: 1010-0057, Pollution Prevention and Control, Extension of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-30

..., and pipeline right-of-way. Operations on the OCS must preserve, protect, and develop oil and natural... protection of human, marine, and coastal environments; to ensure the public a fair and equitable return on... waters or subsoil and seabed, or other occurrences which may cause damage to the environment or to...

Challenges and limitations in studying the shrink-swell and crack dynamics of vertisol soils

USDA-ARS?s Scientific Manuscript database

The need to study the shrink-swell and crack properties of vertic soils has long been recognized given their dynamics in time and space, which modifies the physical properties that impact water and air movement in the soil, flow of water into the subsoil and ground water, and generally alter the hyd...

Using topsoil thickness to improve site-specific phosphorus and potassium management on claypan soil

USDA-ARS?s Scientific Manuscript database

Precise P and K fertilizer management on claypan soils can be difficult due to variable topsoil thickness, or depth to claypan (DTC), across landscapes, nutrient supply from subsoils, and crop removal. Therefore, a study was performed to determine if DTC could be used to improve P and K management f...

Evaluating topsoil depth effects on phosphorus and potassium nutrient dynamics of grain and switchgrass production systems

USDA-ARS?s Scientific Manuscript database

Understanding the effects of fertilizer addition and crop removal on long-term change in soil test phosphorus (STP) and soil test potassium (STK) is crucial for maximizing the use of grower inputs on claypan soils. Due to variable nutrient supply from subsoils and variable crop removal across fields...

Understory plant response to site preparation and fertilization of loblolly and shortleaf pine forests

Treesearch

Dale G. Brockway; Gale L. Wolters; H.A. Pearson; Ronald E. Thill; V. Clark Baldwin; A. Martin

1998-01-01

In developing an improved understanding of the dynamics of understory plant composition and productivity in Coastal Plaii forest ecosystems, we examined theiniluenceof site preparation and phosphorus fertilization on the successional trends of shrubs and herbaceous plants growing on lands of widely ranging subsoil texture in Arkansas, Louisiana, and Texas which are...

HIGH RISE OR LOW RISE. A STUDY OF DECISION FACTORS IN RESIDENCE HALLS PLANNING.

ERIC Educational Resources Information Center

Educational Facilities Labs., Inc., New York, NY.

THE PURPOSE OF THIS REPORT IS TO SERVE COLLEGE OFFICIALS, HOUSING ADMINISTRATORS, PLANNING GROUPS AND ARCHITECTS BY FOCUSING ON THE DECISION FACTORS WHICH RELATE TO HIGH-RISE AND LOW-RISE STUDENT HOUSING. DECISION FACTORS INCLUDE--(1) LAND USE IMPLICATIONS, (2) SITE REQUIREMENTS--BUILDING CODES, SUB-SOIL CONSIDERATIONS, NATURAL TERRAIN,…

Enhancing the soil organic matter pool through biomass incorporation

Treesearch

Felipe G. Sanchez; Emily A. Carter; John F. Klepac

2003-01-01

A study was installed in the Upper Coastal Plain of South Carolina, USA that sought to examine the impact of incorporating downed slash materials into subsoil layers on soil chemical and physical properties as compared with the effect of slash materials left on the soil surface. Baseline levels of slash were estimated by establishing transects within harvested stands...

Comparison of tillage equipment for improving soil conditions and root health in bareroot nurseries

Treesearch

Jennifer Juzwik; Kathryn Kromroy; Raymond Allmaras

2002-01-01

Two series of trials were conducted in northern bareroot forest nurseries to determine: 1) the effects of different incorporation implements and two chemical application rates on the efficacy of dazomet fumigation; and 2) soil penetration resistance in the vertical soil profile following sub-soiling by two different implements. When target pests were located > 18 cm...

Comparison of Tillage for Improving Soil Conditions and Root Health in Barefoot Nurseries

Treesearch

Jennifer Juzwik; Kathryn Kromroy; Raymond Allmaras

2002-01-01

Two series of trials were conducted in northern bareroot forest nurseries to determine: 1) the effects of different incorporation implements and two chemical application rates on the efficacy of dazomet fumigation; and 2) soil penetration resistance in the vertical soil profile following sub-soiling by two different implements. When target pests were located > 18 cm...

Use of Municipal Sewage Sludge for Improvement of Forest Sites in the Southeast

Treesearch

Charles R. Berry

1987-01-01

In eight field experiments dried municipal sewage sludge was applied to forest sites before planting of seedlings. In all cases, tree growth was faster on sludge-amended plots than on plots that received fertilizer and lime or no amendment. Deep subsoiling was beneficial regardless of Soil amendment. Where weeds were plentiful at the outset, they became serious...

Effects of forest road amelioration techniques on soil bulk density, surface runoff, sediment transport, soil moisture and seedling growth

Treesearch

Randy K. Kolka; Mathew F. Smidt

2004-01-01

Although numerous methods have been used to retire roads, new technologies have evolved that can potentially ameliorate soil damage, lessen ,the generation of nonpoint source pollution and increase tree productivity on forest roads. In this study we investigated the effects of three forest road amelioration techniques, subsoiling, recontouring and traditional...

Red Maple (Acer rubrum L.) Growth and Foliar Nutrient Responses to Soil Fertility Level and Water Regime

Treesearch

C. H. Pham; Howard G. Halverson; Gordon M. Heisler

1978-01-01

Red maple (Acer rubrum L.) seedlings were grown in a greenhouse using three treatments: two soil horizons, two soil moisture regimes, and three nutrient levels. Fertilization increased growth under moist conditions on the more fertile topsoil. Under dry conditions, fertilization had no effect on growth in subsoil, and slightly increased growth in...

3D geophysical imaging for site-specific characterization plan of an old landfill.

PubMed

Di Maio, R; Fais, S; Ligas, P; Piegari, E; Raga, R; Cossu, R

2018-06-01

As it is well-known, the characterization plan of an old landfill site is the first stage of the project for the treatment and reclamation of contaminated lands. It is a preliminary in-situ study, with collection of data related to pollution phenomena, and is aimed at defining the physical properties and the geometry of fill materials as well as the possible migration paths of pollutants to the surrounding environmental targets (subsoil and groundwater). To properly evaluate the extent and potential for subsoil contamination, waste volume and possible leachate emissions from the landfill have to be assessed. In such perspective, the integrated use of geophysical methods is an important tool as it allows a detailed 3D representation of the whole system, i.e. waste body and hosting environment (surrounding rocks). This paper presents a very accurate physical and structural characterization of an old landfill and encasing rocks obtained by an integrated analysis of data coming from a multi-methodological geophysical exploration. Moreover, drillings were carried out for waste sampling and characterization of the landfill body, as well as for calibration of the geophysical modeling. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impact of Preservation of Subsoil Water Act on Groundwater Depletion: The Case of Punjab, India.

PubMed

Tripathi, Amarnath; Mishra, Ashok K; Verma, Geetanjali

2016-07-01

Indian states like Punjab and Haryana, epicenters of the Green Revolution, are facing severe groundwater shortages and falling water tables. Recognizing it as a serious concern, the Government of Punjab enacted the Punjab Preservation of Subsoil Water Act in 2009 (or the 2009 act) to slow groundwater depletion. The objective of this study is to assess the impact of this policy on groundwater depletion, using panel data from 1985 to 2011. Results from this study find a robust effect of the 2009 act on reducing groundwater depletion. Our models for pre-monsoon, post-monsoon, and overall periods of analysis find that since implementation of the 2009 act, groundwater tables have improved significantly. Second, our study reveals that higher shares of tube wells per total cropped area and increased population density have led to a significant decline in the groundwater tables. On the other hand, rainfall and the share of area irrigated by surface water have had an augmenting effect on groundwater resources. In the two models, pre-monsoon and post-monsoon, this study shows that seasonality plays a key role in determining the groundwater table in Punjab. Specifically, monsoon rainfall has a very prominent impact on groundwater.

Health assessment for Louisiana Army Ammunition Plant, Shreveport, Webster County, Louisiana, Region 6. CERCLIS No. LA0213820533. Preliminary report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1989-04-10

The Louisiana Army Ammunition Plant (LAAP) is listed on the National Priorities List. The site is a 15,000-acre Federal facility located in Shreveport (Webster Parish), Louisiana. On-site ground water beneath 16 unlined surface impoundments near the southern boundary is contaminated. Access to LAAP is restricted and under 24-hour security. Contaminants include 2,4,6-trinitrotoluene (TNT), cyclonite (RDX), trinitrobenzene (TNB), and homocyclonite (HMX). Preliminary on-site sampling results have identified TNT (493,133 ppm in sediment/subsoil, 483,556 ppm in sludge, 1,033 ppm in surface soil, 7 ppm in surface water, and 18 ppm in ground water), RDX (60,224 ppm in sediment/subsoil, 602 ppm in surfacemore » soil, 60,224 ppm in sludge, and 14 ppm in ground water), TNB (2 ppm in surface water and 8 ppm in ground water), and HMX (4 ppm in ground water). Based on available information, the site is considered to be of potential public health concern because of the risk to human health caused by the possibility of human exposure to hazardous substances.« less

Semi-Quantitative Evaluation of Secondary Carbonates via Portable X-ray Fluorescence Spectrometry

NASA Astrophysics Data System (ADS)

Chakraborty, Somsubhra; Weindorf, David; Weindorf, Camille; Duda, Bogdan; Pennington, Sarah; Ortiz, Rebekah

2017-04-01

Secondary calcium carbonate commonly occurs in subsoils of semi-arid soils worldwide. In US Soil Taxonomy, such horizons are frequently described as Bk, Bkk, Bkm, Bkkm, or Ck horizons at variable stages of development. Specifically, the Soil Survey Staff uses a qualitative scale of one through six to indicate differential developmental stages. However, considerable disagreement exists even among experienced soil scientists. Evaluating 75 soil samples from across four US states, a portable X-ray fluorescence (PXRF) spectrometer was used to quantify the total soil Ca content and compare it to average developmental stage scores as determined by a panel of Soil Survey Staff personnel. Samples were evaluated both as intact aggregates as well as ground (<2 mm), homogenized powders. PXRF readings of total soil Ca concentration steadily increased under both conditions as developmental stage progressed. However, minimal difference was observed between stage five and six carbonate accumulation. Stage three showed the widest variability in total soil Ca. Given than PXRF cannot distinguish between primary and secondary CaCO3 in soils, interpretation by the analyst remains essential. Nonetheless, PXRF provides an important tool for assessing carbonate laden subsoils providing elemental differentiation beyond that perceived by the human eye.

Wave equation datuming applied to S-wave reflection seismic data

NASA Astrophysics Data System (ADS)

Tinivella, U.; Giustiniani, M.; Nicolich, R.

2018-05-01

S-wave high-resolution reflection seismic data was processed using Wave Equation Datuming technique in order to improve signal/noise ratio, attenuating coherent noise, and seismic resolution and to solve static corrections problems. The application of this algorithm allowed obtaining a good image of the shallow subsurface geological features. Wave Equation Datuming moves shots and receivers from a surface to another datum (the datum plane), removing time shifts originated by elevation variation and/or velocity changes in the shallow subsoil. This algorithm has been developed and currently applied to P wave, but it reveals the capacity to highlight S-waves images when used to resolve thin layers in high-resolution prospecting. A good S-wave image facilitates correlation with well stratigraphies, optimizing cost/benefit ratio of any drilling. The application of Wave Equation Datuming requires a reliable velocity field, so refraction tomography was adopted. The new seismic image highlights the details of the subsoil reflectors and allows an easier integration with borehole information and geological surveys than the seismic section obtained by conventional CMP reflection processing. In conclusion, the analysis of S-wave let to characterize the shallow subsurface recognizing levels with limited thickness once we have clearly attenuated ground roll, wind and environmental noise.

Characterisation of soils under long-term crop cultivation without fertilisers: a case study in Japan.

PubMed

Nakatsuka, Hiroko; Tamura, Kenji

2016-01-01

Certain farms in Japan, namely unfertilised farms (UFs), have been able to maintain high productivity for over 40 years without applying fertilisers or composts. This study aimed to characterise the physicochemical, biological and micromorphological properties of soil in UFs compared with control farms in Eniwa and Nariita and to identify characteristics that are associated with crop productivity. In UFs, no plough pan was observed. The thickness of the effective soil depth (ESD) of UFs was greater than that of CFs. The concentrations of soil organic carbon, total nitrogen and nitrate-nitrogen in ESD of UFs were higher than those in ESD of CFs. Soil microstructure observations indicated the strong development of a granular microstructure with large amounts of void space and a high fractal dimension in both surface and subsoil horizons of UFs. Dry yield had a strong correlation with ESD thickness and fractal dimension of voids. Thus, the management of unfertilised cultivation promoted the development of soil aggregation in both A and B horizons. The increase in ESD, soil pore spaces and complexity with the development of subsoil structure improved the productivity of unfertilised cultivation.

Present and future challenges of urban systems affected by seawater and its intrusion: the case of Venice, Italy

NASA Astrophysics Data System (ADS)

di Sipio, Eloisa; Zezza, Fulvio

2011-11-01

In lagoonal and marine environments, both historic monuments and recent buildings suffer from severe salt damage caused by sea flooding, sea-level rise and frequent storm events. Salt-water contamination of groundwater systems, a widespread phenomenon typical of coastal areas, can lead to a deterioration not only of the quality of fresh groundwater resources, but also of building materials in urban settlements. A general overview is given of the hydrogeological configuration of the subsoil of Venice (Italy), with particular reference to the shallow groundwater circulation. The relationship between the seawater in the subsoil and salt decay processes, due to salt crystallization, is highlighted. These processes affect civil constructions in Venice's historic center. Perched aquifers, influenced by tide variations and characterized by salt-water intrusion, favor the transport of salts within masonry walls through the action of rising damp. In fact, foundations, in direct contact with the aquifers, may become a preferential vehicle for the transportation of salt within buildings. Decay patterns of different building materials can be detected through non-destructive techniques, which can identify sea-salt damage and therefore assist in the preservation of cultural heritage in coastal areas.

MX Siting Investigation. Geotechnical Evaluation. Volume I. Arizona Verification Studies, FY 79, and Geotechnical Data, La Posa CDP, Arizona.

DTIC Science & Technology

1979-11-15

COMPACTION 7-12 [2] 9 SUITABILITY AS ROAD SUBGRADE (’) poor to fair lair to go SUITABILITY AS ROAD SUBBASE OR BASE (1) poor poor to fai aJ 2.1-10.9 1.1...wave velocity of 9350 fps (2850 mps). These variable seismic wave velocities indicate nonuniformity in subsoil density and cementation. Electrical

Effects of Subsoiling and Competition Control on First Year Survival and Growth of Four Hardwood Species

Treesearch

Andrew W. Ezell; Mark W. Shankle

2004-01-01

Afforestation of abandoned agricultural land with hardwood seedlings is being conducted on thousands of acres in the South annually. More than 300,000 acres have been planted under the auspices of the Wetland Reserve Program, and other cost-share programs also promote the planting of hardwood species. Unfortunately, survival in many of these planting efforts has been...

Compositional changes of soil organic matter with cropping time were more profound in subsoils and distinct between Phaeozem and Chernozem in Northeast China

USDA-ARS?s Scientific Manuscript database

Soil organic matter (SOM) contributes to soil processes and is found both in shallow and deep soil layers. Its activity can be affected by its chemical composition, yet knowledge is incomplete of how land use alters the structural composition of SOM throughout the profiles of different soil types. T...

Evaluation of morphometric parameters derived from Cartosat-1 DEM using remote sensing and GIS techniques for Budigere Amanikere watershed, Dakshina Pinakini Basin, Karnataka, India

NASA Astrophysics Data System (ADS)

Dikpal, Ramesh L.; Renuka Prasad, T. J.; Satish, K.

2017-12-01

The quantitative analysis of drainage system is an important aspect of characterization of watersheds. Using watershed as a basin unit in morphometric analysis is the most logical choice because all hydrological and geomorphic processes occur within the watershed. The Budigere Amanikere watershed a tributary of Dakshina Pinakini River has been selected for case illustration. Geoinformatics module consisting of ArcGIS 10.3v and Cartosat-1 Digital Elevation Model (DEM) version 1 of resolution 1 arc Sec ( 32 m) data obtained from Bhuvan is effectively used. Sheet and gully erosion are identified in parts of the study area. Slope in the watershed indicating moderate to least runoff and negligible soil loss condition. Third and fourth-order sub-watershed analysis is carried out. Mean bifurcation ratio ( R b) 3.6 specify there is no dominant influence of geology and structures, low drainage density ( D d) 1.12 and low stream frequency ( F s) 1.17 implies highly infiltration subsoil material and low runoff, infiltration number ( I f)1.3 implies higher infiltration capacity, coarse drainage texture ( T) 3.40 shows high permeable subsoil, length of overland flow ( L g) 0.45 indicates under very less structural disturbances, less runoff conditions, constant of channel maintenance ( C) 0.9 indicates higher permeability of subsoil, elongation ratio ( R e) 0.58, circularity ratio ( R c) 0.75 and form factor ( R f) 0.26 signifies sub-circular to more elongated basin with high infiltration with low runoff. It was observed from the hypsometric curves and hypsometric integral values of the watershed along with their sub basins that the drainage system is attaining a mature stage of geomorphic development. Additionally, Hypsometric curve and hypsometric integral value proves that the infiltration capacity is high as well as runoff is low in the watershed. Thus, these mormometric analyses can be used as an estimator of erosion status of watersheds leading to prioritization for taking up soil and water conservation measures.

Wet-dry cycles impact DOM retention in subsurface soils

NASA Astrophysics Data System (ADS)

Olshansky, Yaniv; Root, Robert A.; Chorover, Jon

2018-02-01

Transport and reactivity of carbon in the critical zone are highly controlled by reactions of dissolved organic matter (DOM) with subsurface soils, including adsorption, transformation and exchange. These reactions are dependent on frequent wet-dry cycles common to the unsaturated zone, particularly in semi-arid regions. To test for an effect of wet-dry cycles on DOM interaction and stabilization in subsoils, samples were collected from subsurface (Bw) horizons of an Entisol and an Alfisol from the Catalina-Jemez Critical Zone Observatory and sequentially reacted (four batch steps) with DOM extracted from the corresponding soil litter layers. Between each reaction step, soils either were allowed to air dry (wet-dry treatment) before introduction of the following DOM solution or were maintained under constant wetness (continually wet treatment). Microbial degradation was the dominant mechanism of DOM loss from solution for the Entisol subsoil, which had higher initial organic C content, whereas sorptive retention predominated in the lower C Alfisol subsoil. For a given soil, bulk dissolved organic C losses from solution were similar across treatments. However, a combination of Fourier transform infrared (FTIR) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopic analyses revealed that wet-dry treatments enhanced the interactions between carboxyl functional groups and soil particle surfaces. Scanning transmission X-ray microscopy (STXM) data suggested that cation bridging by Ca2+ was the primary mechanism for carboxyl association with soil surfaces. STXM data also showed that spatial fractionation of adsorbed OM on soil organo-mineral surfaces was diminished relative to what might be inferred from previously published observations pertaining to DOM fractionation on reaction with specimen mineral phases. This study provides direct evidence of the role of wet-dry cycles in affecting sorption reactions of DOM to a complex soil matrix. In the soil environment, where wet-dry cycles occur at different frequencies from site to site and along the soil profile, different interactions between DOM and soil surfaces are expected and need to be considered for the overall assessment of carbon dynamics.

Recovery Act. Sub-Soil Gas and Fluid Inclusion Exploration and Slim Well Drilling, Pumpernickel Valley, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fairbank, Brian D.

2015-03-27

Nevada Geothermal Power Company (NGP) was awarded DOE Award DE-EE0002834 in January 2010 to conduct sub-soil gas and fluid inclusion studies and slim well drilling at its Black Warrior Project (now known as North Valley) in Washoe and Churchill Counties, Nevada. The project was designed to apply highly detailed, precise, low-cost subsoil and down-hole gas geochemistry methods from the oil and gas industry to identify upflow zone drilling targets in an undeveloped geothermal prospect. NGP ran into multiple institutional barriers with the Black Warrior project relating to property access and extensive cultural survey requirement. NGP requested that the award bemore » transferred to NGP’s Pumpernickel Valley project, due to the timing delay in obtaining permits, along with additional over-budget costs required. Project planning and permit applications were developed for both the original Black Warrior location and at Pumpernickel. This included obtaining proposals from contractors able to conduct required environmental and cultural surveying, designing the two-meter probe survey methodology and locations, and submitting Notices of Intent and liaising with the Bureau of Land Management to have the two-meter probe work approved. The award had an expiry date of April 30, 2013; however, due to the initial project delays at Black Warrior, and the move of the project from Black Warrior to Pumpernickel, NGP requested that the award deadline be extended. DOE was amenable to this, and worked with NGP to extend the deadline. However, following the loss of the Blue Mountain geothermal power plant in Nevada, NGP’s board of directors changed the company’s mandate to one of cash preservation. NGP was unable to move forward with field work on the Pumpernickel property, or any of its other properties, until additional funding was secured. NGP worked to bring in a project partner to form a joint venture on the property, or to buy the property. This was unsuccessful, and NGP notified the DOE on February 13, 2014 that it would not be able to complete the project objectives before the recovery act awards deadline and submitted a mutual termination request to the DOE which was accepted.« less

Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species

NASA Astrophysics Data System (ADS)

Fritsch, E.; Allard, Th.; Benedetti, M. F.; Bardy, M.; do Nascimento, N. R.; Li, Y.; Calas, G.

2009-04-01

The development of podzols in lateritic landscapes of the upper Amazon basin contributes to the exportation of organic carbon and associated metals in the black waters of the Negro River watershed. We have investigated the distribution of Fe III in the clay-size fraction of eight organic-rich horizons of waterlogged plateau podzols, to unravel the weathering conditions and mechanisms that control its transfer to the rivers. The speciation and amount of Fe III stored in residual mineral phases of laterites, or bound to organic compounds of weakly and well-expressed podzols, were determined by electron paramagnetic resonance spectroscopy combined with chemical analyses. Reducing conditions restrict the production of organo-Fe complexes in the subsoil B-horizons of waterlogged podzols and most of the Fe 2+ released from the dissolution of Fe-oxides is exported to the rivers via the perched groundwater. However, significant amounts of diluted Fe III bound to organic ligands (Fe IIIOM) and nano Fe-oxides are produced at the margin of the depression in the topsoil A horizons of weakly expressed podzols due to shorter periods of anoxia. The downward translocation of organically bound metals from topsoil A to subsoil B-horizons of podzols occurs in shorter distances for Fe than it does for Al. This separation of secondary Fe species from Al species is attributed to the physical fractionation of their organic carriers in texture contrasted B-horizons of podzols, as well as to the effect of pH on metal speciation in soil solutions and metal binding onto soil organic ligands (mostly for Al). This leads us to consider the topsoil A horizons of weakly expressed podzols, as well as the subsoil Bh horizon of better-expressed ones, as the main sources for the transfer of Fe IIIOM to the rivers. The concentration of Fe IIIOM rises from soil sources to river colloids, suggesting drastic biogeochemical changes in more oxygenated black waters of the Negro River watershed. The contribution of soil organic matter to the transfer of Fe to rivers is likely at the origin of the peculiar Fe isotope pattern recently recognized in podzolic environments.

Greenhouse gas flux and crop productivity after 10 years of reduced and no tillage in a wheat-maize cropping system.

PubMed

Tian, Shenzhong; Wang, Yu; Ning, Tangyuan; Zhao, Hongxiang; Wang, Bingwen; Li, Na; Li, Zengjia; Chi, Shuyun

2013-01-01

Appropriate tillage plays an important role in mitigating the emissions of greenhouse gases (GHG) in regions with higher crop yields, but the emission situations of some reduced tillage systems such as subsoiling, harrow tillage and rotary tillage are not comprehensively studied. The objective of this study was to evaluate the emission characteristics of GHG (CH4 and N2O) under four reduced tillage systems from October 2007 to August 2009 based on a 10-yr tillage experiment in the North China Plain, which included no-tillage (NT) and three reduced tillage systems of subsoil tillage (ST), harrow tillage (HT) and rotary tillage (RT), with the conventional tillage (CT) as the control. The soil under the five tillage systems was an absorption sink for CH4 and an emission source for N2O. The soil temperature positive impacted on the CH4 absorption by the soils of different tillage systems, while a significant negative correlation was observed between the absorption and soil moisture. The main driving factor for increased N2O emission was not the soil temperature but the soil moisture and the content of nitrate. In the two rotation cycle of wheat-maize system (10/2007-10/2008 and 10/2008-10/2009), averaged cumulative uptake fluxes of CH4 under CT, ST, HT, RT and NT systems were approximately 1.67, 1.72, 1.63, 1.77 and 1.17 t ha(-1) year(-1), respectively, and meanwhile, approximately 4.43, 4.38, 4.47, 4.30 and 4.61 t ha(-1) year(-1) of N2O were emitted from soil of these systems, respectively. Moreover, they also gained 33.73, 34.63, 32.62, 34.56 and 27.54 t ha(-1) yields during two crop-rotation periods, respectively. Based on these comparisons, the rotary tillage and subsoiling mitigated the emissions of CH4 and N2O as well as improving crop productivity of a wheat-maize cropping system.

Greenhouse Gas Flux and Crop Productivity after 10 Years of Reduced and No Tillage in a Wheat-Maize Cropping System

PubMed Central

Tian, Shenzhong; Wang, Yu; Ning, Tangyuan; Zhao, Hongxiang; Wang, Bingwen; Li, Na; Li, Zengjia; Chi, Shuyun

2013-01-01

Appropriate tillage plays an important role in mitigating the emissions of greenhouse gases (GHG) in regions with higher crop yields, but the emission situations of some reduced tillage systems such as subsoiling, harrow tillage and rotary tillage are not comprehensively studied. The objective of this study was to evaluate the emission characteristics of GHG (CH4 and N2O) under four reduced tillage systems from October 2007 to August 2009 based on a 10-yr tillage experiment in the North China Plain, which included no-tillage (NT) and three reduced tillage systems of subsoil tillage (ST), harrow tillage (HT) and rotary tillage (RT), with the conventional tillage (CT) as the control. The soil under the five tillage systems was an absorption sink for CH4 and an emission source for N2O. The soil temperature positive impacted on the CH4 absorption by the soils of different tillage systems, while a significant negative correlation was observed between the absorption and soil moisture. The main driving factor for increased N2O emission was not the soil temperature but the soil moisture and the content of nitrate. In the two rotation cycle of wheat-maize system (10/2007–10/2008 and 10/2008–10/2009), averaged cumulative uptake fluxes of CH4 under CT, ST, HT, RT and NT systems were approximately 1.67, 1.72, 1.63, 1.77 and 1.17 t ha−1 year−1, respectively, and meanwhile, approximately 4.43, 4.38, 4.47, 4.30 and 4.61 t ha−1 year−1 of N2O were emitted from soil of these systems, respectively. Moreover, they also gained 33.73, 34.63, 32.62, 34.56 and 27.54 t ha−1 yields during two crop-rotation periods, respectively. Based on these comparisons, the rotary tillage and subsoiling mitigated the emissions of CH4 and N2O as well as improving crop productivity of a wheat-maize cropping system. PMID:24019923

A Physics Based Vehicle Terrain Interaction Model for Soft Soil off-Road Vehicle Simulations

DTIC Science & Technology

2012-01-01

assumed terrain deformation, use of empirical relationships for the deformation, or finite/discrete element approaches for the terrain. A real-time...vertical columns of soil, and the deformation of each is modeled using visco-elasto-plastic compressibility relationships that relate subsoil pressures to...produced by tractive and turning forces will also be incorporated into the model. Both the vertical and horizontal force/displacement relationships

The problems and prospects of the public-private partnership in the Russian fuel and energy sector

NASA Astrophysics Data System (ADS)

Nikitenko, SM; Goosen, EV

2017-02-01

This article highlights some opportunities for shifting the paradigm for the development of natural resources in the Russian fuel and energy sector using public-private partnership instruments. It shows three main directions for developing public-private partnerships in the area of subsoil use and emphasizes the role of innovations in implementing the most promising projects in the fuel and energy sector of Russia.

Water Relations and Gas Exchange of Loblolly Pine Seedlings Under Different Cultural Practices on Poorly Drained Sites in Arkansas

Treesearch

Mohd S. Rahman; Michael G. Messina; Richard F. Fisher

2002-01-01

Substantial forest acreage in the south-central U.S. is seasonally water-logged due to an underlying fragipan. Severely restricted drainage in the non-growing season leads to a reduced subsoil zone, which restricts root respiration. The same sites may also be subjected to summer drought. These climatic and edaphic problems may result in low seedling survival and...

In situ phytoremediation of arsenic- and metal-polluted pyrite waste with field crops: effects of soil management.

PubMed

Vamerali, Teofilo; Bandiera, Marianna; Mosca, Giuliano

2011-05-01

Sunflower, alfalfa, fodder radish and Italian ryegrass were cultivated in severely As-Cd-Co-Cu-Pb-Zn-contaminated pyrite waste discharged in the past and capped with 0.15m of unpolluted soil at Torviscosa (Italy). Plant growth and trace element uptake were compared under ploughing and subsoiling tillages (0.3m depth), the former yielding higher contamination (∼30%) in top soil. Tillage choice was not critical for phytoextraction, but subsoiling enhanced above-ground productivity, whereas ploughing increased trace element concentrations in plants. Fodder radish and sunflower had the greatest aerial biomass, and fodder radish the best trace element uptake, perhaps due to its lower root sensitivity to pollution. Above-ground removals were generally poor (maximum of 33mgm(-2) of various trace elements), with Zn (62%) and Cu (18%) as main harvested contaminants. The most significant finding was of fine roots proliferation in shallow layers that represented a huge sink for trace element phytostabilisation. It is concluded that phytoextraction is generally far from being an efficient management option in pyrite waste. Sustainable remediation requires significant improvements of the vegetation cover to stabilise the site mechanically and chemically, and provide precise quantification of root turnover. Copyright © 2011 Elsevier Ltd. All rights reserved.

Intrinsic vulnerability assessment of shallow aquifers of the sedimentary basin of southwestern Nigeria

PubMed Central

2018-01-01

The shallow groundwater of the multi-layered sedimentary basin aquifer of southwestern Nigeria was assessed based on its intrinsic vulnerability property. The vulnerability evaluation involves determining the protective cover and infiltration condition of the unsaturated zone in the basin. This was achieved using the PI (P stands for protective cover effectiveness of the overlying lithology and I indicates the degree of infiltration bypass) vulnerability method of the European vulnerability approach. The PI method specifically measures the protection cover and the degree to which the protective cover is bypassed. Intrinsic parameters assessed were the subsoil, lithology, topsoil, recharge and fracturing for the protective cover. The saturated hydraulic conductivity of topsoil, infiltration processes and the lateral surface and subsurface flow were evaluated for the infiltration bypassed. The results show moderate to very low vulnerability areas. Low vulnerability areas were characterised by lithology with massive sandstone and limestone, subsoils of sandy loam texture, high slopes and high depth to water table. The moderate vulnerability areas were characterised by high rainfall and high recharge, low water table, unconsolidated sandstones and alluvium lithology. The intrinsic vulnerability properties shown in vulnerability maps will be a useful tool in planning and monitoring land use activities that can be of impact in groundwater pollution.

Vadose zone microbiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kieft, Thomas L.; Brockman, Fred J.

2001-01-17

The vadose zone is defined as the portion of the terrestrial subsurface that extends from the land surface downward to the water table. As such, it comprises the surface soil (the rooting zone), the underlying subsoil, and the capillary fringe that directly overlies the water table. The unsaturated zone between the rooting zone and the capillary fringe is termed the "intermediate zone" (Chapelle, 1993). The vadose zone has also been defined as the unsaturated zone, since the sediment pores and/or rock fractures are generally not completely water filled, but instead contain both water and air. The latter characteristic results inmore » the term "zone of aeration" to describe the vadose zone. The terms "vadose zone," "unsaturated zone", and "zone of aeration" are nearly synonymous, except that the vadose zone may contain regions of perched water that are actually saturated. The term "subsoil" has also been used for studies of shallow areas of the subsurface immediately below the rooting zone. This review focuses almost exclusively on the unsaturated region beneath the soil layer since there is already an extensive body of literature on surface soil microbial communities and process, e.g., Paul and Clark (1989), Metting (1993), Richter and Markowitz, (1995), and Sylvia et al. (1998); whereas the deeper strata of the unsaturated zone have only recently come under scrutiny for their microbiological properties.« less

Functional Villa Tugendhat and its Geological Subsoil - Design of a New Geotourism Place

NASA Astrophysics Data System (ADS)

Duraj, Miloš; Cheng, Xianfeng; Niemiec, Dominik; Arencibia Montero, Orlando; Durďák, Jan

2017-10-01

Functionalist villa Tugendhat deserves to be one of the UNESCO heritage sites. The author of this building was a prominent German architect, Ludwig Mies van der Rohe, who accepted the contract from Greta and Fritz Tugendhat. From today’s perspective, this building is one of the most important pre-war works of this architect. The 1928 architectural design was subsequently very quickly completed and the construction was completed in 1930. The Tugendhat family lived in a villa until 1938. During World War II it was confiscated by German occupation forces. At the end of the war, it was used by the Red Army and later served for the state. During this period, this building did not avoid warfare or later destruction of both the building and parts of the facility. The importance of this building was recognized in 1969, when the villa was placed on the State List of Cultural Monuments. In the 80’s was the first major renovation of the building, which is often criticized. The second, last reconstruction took place in the years 2010 - 2012. During these reconnaissance works there were also old, temporarily calming landslides, which were subsequently solved. For this reason, the site is suitable for geotourism as an example of architectural monuments versus geological subsoil.

Socio-economic development of territories based on the principles of public-private partnership in the sphere of comprehensive mineral exploration

NASA Astrophysics Data System (ADS)

Nikitenko, S. M.; Goosen, E. V.

2017-09-01

The article explores the possibility of using instruments of public-private partnership for a paradigm shift in subsoil use in the fuel and energy complex of Russia. The modern Russian fuel and energy complex (FEC) is characterized by high depreciation of production assets, technological inferiority compared to the developed countries, etc. The solution to all these problems seems to be closely connected with the transition from extensive use of natural resources to comprehensive mineral exploration (CME), with a stable socio-economic development of territories and mutually beneficial partnership between science, business and government based on the principles of public-private partnership (PPP). The article discussed the three main directions of PPP projects development in subsoil use. The first direction comprises the projects aimed at the establishment of core mineral resource businesses on the basis of concession agreements and production sharing contracts. The second direction concerns the projects focused on the development of territories and objects of industrial and social infrastructure in resource regions. The third direction is formed by the projects aimed at the development of new industries, focused on the creation of centers of innovative development, formation of markets for innovative products and innovative clusters in the energy industry.

Soil compaction--indicators for the assessment of harmful changes to the soil in the context of the German Federal Soil Protection Act.

PubMed

Lebert, Matthias; Böken, Holger; Glante, Frank

2007-02-01

Soil compaction in agriculture induced by large-scale equipment is of growing concern. Heavy wheel loads used in arable cropping have the potential to cause irreversible damage to the subsoil structure and may lead to harmful soil compaction. In order to sustain or improve soil health or fitness on a sustainable basis, indicators are needed to assess the changes in the soil structure and the respective soil functions. This requires an adequate verification of methods for distinguishing between the impairment of soil structure and the disruption of soil functions, and for the respective subject of protection. In this article the link between existing models of soil physical prognosis, practical guidelines, and criteria for the identification of affected soil structure is demonstrated, and a viable concept to distinguish harmful changes to the soil is presented. The concept consists of methods for soil physical analysis such as "pre-compression stress" and "loading ratio", practical recommendations for best management practice, and an indicator-based model for the identification of harmful subsoil compaction derived from a research project for the German Federal Environmental Agency, making it possible to determine for a respective location the required level of action far beyond the common practice of precautions against harmful soil compaction.

Do chemical gradients within soil aggregates reflect plant/soil interactions?

NASA Astrophysics Data System (ADS)

Krüger, Jaane; Hallas, Till; Kinsch, Lena; Stahr, Simon; Prietzel, Jörg; Lang, Friederike

2016-04-01

As roots and hyphae often accumulate at the surface of soil aggregates, their formation and turnover might be related to the bioavailability especially of immobile nutrients like phosphorus. Several methods have been developed to obtain specific samples from aggregate surfaces and aggregate cores and thus to investigate differences between aggregate shell and core. However, these methods are often complex and time-consuming; therefore most common methods of soil analysis neglect the distribution of nutrients within aggregates and yield bulk soil concentrations. We developed a new sequential aggregate peeling method to analyze the distribution of different nutrients within soil aggregates (4-20 mm) from four forest sites (Germany) differing in concentrations of easily available mineral P. Aggregates from three soil depths (Ah, BwAh, Bw) were isolated, air-dried, and peeled with a sieving machine performing four sieving levels with increasing sieving intensity. This procedure was repeated in quadruplicate, and fractions of the same sample and sieving level were pooled. Carbon and N concentration, citric acid-extractable PO4 and P, as well as total element concentrations (P, K, Mg, Ca, Al, Fe) were analyzed. Additionally, synchrotron-based P K-edge XANES spectroscopy was applied on selected samples to detect P speciation changes within the aggregates. The results reveal for most samples a significantly higher C and N concentration at the surface compared to the interior of the aggregates. Carbon and N gradients get more pronounced with increasing soil depth and decreasing P status of study sites. This might be explained by lower aggregate turnover rates of subsoil horizons and intense bioturbation on P-rich sites. This assumption is also confirmed by concentrations of citric acid-extractable PO4 and P: gradients within aggregates are getting more pronounced with increasing soil depth and decreasing P status. However, the direction of these gradients is site-specific: On P-rich study sites the results reveal a significant depletion of citric acid-extractable PO4 and P on aggregate surfaces in subsoil horizons, while at the other study sites a slight enrichment at the aggregate surfaces could be observed. Total P concentrations show no distinct gradients within topsoil aggregates, but a slight P enrichment at the surface of subsoil aggregates at the P-rich site. A strong correlation with the total Al concentrations may indicate a P speciation change within aggregates (e.g., due to acidification processes). These results were also confirmed by P K-edge XANES spectra of aggregate core and shell samples of the P-rich site: In the aggregate shells of topsoil as well as subsoil aggregates, organic P forms are most dominant (82 and 80 %, respectively) than in the aggregate interior (54 and 66%, respectively). Moreover, P in the shell seems to be completely associated to Al, whereas some of the P in the aggregate interior is bound to Fe and/or Ca. Overall, our results show that plant/soil interactions impact on small-scale distribution and bioavailability of nutrients by root uptake and root-induced aggregate engineering.

Naval Law Review, Volume 57, 2009

DTIC Science & Technology

2009-01-01

example, Chile, Ecuador, and Peru agreed to claim sovereign rights over the seabed and subsoil out to a distance of 200 nautical miles despite the fact...fear and nothing moves on freeways that are now effectively sealed by the abandoned cars. A car explodes outside a federal building in Long Beach ...memorandum of understanding between the Navy and Puerto Rico, regarding pollution at the Vieques range). 264 United States Dep’t of Justice v

Little effects on soil organic matter chemistry of density fractions after seven years of forest soil warming.

PubMed

Schnecker, Jörg; Borken, Werner; Schindlbacher, Andreas; Wanek, Wolfgang

2016-12-01

Rising temperatures enhance microbial decomposition of soil organic matter (SOM) and thereby increase the soil CO 2 efflux. Elevated decomposition rates might differently affect distinct SOM pools, depending on their stability and accessibility. Soil fractions derived from density fractionation have been suggested to represent SOM pools with different turnover times and stability against microbial decomposition. To investigate the effect of soil warming on functionally different soil organic matter pools, we here investigated the chemical and isotopic composition of bulk soil and three density fractions (free particulate organic matter, fPOM; occluded particulate organic matter, oPOM; and mineral associated organic matter, MaOM) of a C-rich soil from a long-term warming experiment in a spruce forest in the Austrian Alps. At the time of sampling, the soil in this experiment had been warmed during the snow-free period for seven consecutive years. During that time no thermal adaptation of the microbial community could be identified and CO 2 release from the soil continued to be elevated by the warming treatment. Our results, which included organic carbon content, total nitrogen content, δ 13 C, Δ 14 C, δ 15 N and the chemical composition, identified by pyrolysis-GC/MS, showed no significant differences in bulk soil between warming treatment and control. Surprisingly, the differences in the three density fractions were mostly small and the direction of warming induced change was variable with fraction and soil depth. Warming led to reduced N content in topsoil oPOM and subsoil fPOM and to reduced relative abundance of N-bearing compounds in subsoil MaOM. Further, warming increased the δ 13 C of MaOM at both sampling depths, reduced the relative abundance of carbohydrates while it increased the relative abundance of lignins in subsoil oPOM. As the size of the functionally different SOM pools did not significantly change, we assume that the few and small modifications in SOM chemistry result from an interplay of enhanced microbial decomposition of SOM and increased root litter input in the warmed plots. Overall, stable functional SOM pool sizes indicate that soil warming had similarly affected easily decomposable and stabilized SOM of this C-rich forest soil.

Analysis of hydrological and geotechnical aspects related to landslides caused by rainfall infiltration

NASA Astrophysics Data System (ADS)

Capparelli, Giovanna; La Sala, Gabriella; Vena, Mirko; Donato, Antonio

2015-04-01

A landslide is defined as a perceptible downward and outward movement of slope-forming soil, rock, and vegetation under the influence of gravity. Landslides can be triggered by both natural and human-induced changes in the environment. However rainfall is recognized as a major precursor for many types of slope movements. As a result of rainfall events and subsequent infiltration into the subsoil, the soil moisture can be significantly changed with a decrease in matric suction in unsaturated soil layers and/or increase in pore-water pressure in saturated layers. As a consequence, in these cases, the shear strength can be reduced enough to trigger the failure. An effective way to develop such an understanding is by means of computer simulation using numerical model. As part of the project PON "Integrated Early Warning System" our main objective was just to develop a numerical models that was able to consider the relation between rainfall, pore pressure and slope stability taking into account several components, including specific site conditions, mechanical, hydraulic and physical soil properties, local seepage conditions, and the contribution of these to soil strength. In this work the mechanism behind rainfall-triggered landslides is modeled by using combined infiltration, seepage and stability analyses. This method allows the evaluation of the terrain and its response based on geological, physical, hydrogeological and mechanical characteristics. The model is based on the combined use of two modules: an hydraulic module, to analyze the subsoil water circulation due to the rainfall infiltration under transient conditions and a geotechnical module, which provides indications regarding the slope stability. With regard to hydraulic module, variably saturated porous media flows have been modeled by the classical nonlinear Richards equation; in the geotechnical module the differential equilibrium equations have been solved taking into account the linear constitutive equations (plane stress) and strain-displacement relationship. By means of the model it is possible to analyze subsoil water circulation, safety factor of the slope subjected to gravity loading and to the pore pressure calculated from hydraulic module, displacement, strain and stress under the effect of rainfall infiltration. As an application case, the analysis and the representative results obtained for the Torre Orsaia landslide (Campania region - Southern Italy) are described.

Ambient noise tomography for characterize the subsoil structure below a collapsed mine. Integration with 3D models of electric resistivity tomography and micro-gravity data inversion

NASA Astrophysics Data System (ADS)

Cárdenas-Soto, M.; Tejero, A.; Nava-Flores, M.; Zenil, D. E.; Vidal-Garcia, M.; Garcia-Serrano, A.

2016-12-01

In this work we build 3D Vs models using seismic tomography of ambient noise. The goal is to characterize the subsurface structure in order to explore the causes of a sudden mine collapse in the 2nd section of Chapultepec park, Mexico City, near to a recreation lake whose subsoil is composed of vulcano-sedimentary materials that were economically exploited in the mid-20th century, leaving a series of underground mines that were rehabilitated for the construction of the Park. In this site we record ambient noise continuously at a 250 Hz sampling rate by intervals of 30 min in three arrays of quadrangular shape with 64 - 4.5 Hz vertical geophones separated 2m. In order to confront the seismic interferometry results, we also obtain 3D models derivated from Electrical Resistivity Tomography (ERT), and inverted surface micro-gravity data. The correlograms show a well defined pulse for those pairs of receivers whose backazimut is perpendicular to the beltway, which is the main source that generates ambient noise. We show that pulses had a dispersive character due to that define a dispersion curve (fundamental mode of Rayleigh wave) whose velocity values are close to 700 m/s at a frequency of 5 Hz, and tend to average values of 380 m/s in frequencies close to 16 Hz. Then, we build tomography images from the maximum time of the envelope pulse filtering in 18 center frequencies between 4 to 16 Hz. Through the relationship f=Vs/4z we create a 3D model in function of the seudo-depth (z). This model allows to distinguish the irregularity of the subsoil around the mine colapse (5m depth), which underlies a competent structure (Vs>450 m/s) surrounded by vulcano sedimentary material with low Vs values (200 m/s). ERT model show that the low velocity zones are associated with saturation areas, result that is corroborated by low-density values derived from micro-gravity model. The results indicate that the collapse was produced by the hydrostatic imbalance of the competent materials, which are the artificial filling that covers the different mined areas.

The spatial extent of agriculturally-induced topsoil removal in the Midwestern United States

NASA Astrophysics Data System (ADS)

Thaler, E.; Larsen, I. J.; Yu, Q.; Keiluweit, M.

2017-12-01

Human-induced erosion of soil organic carbon (SOC) degrades soils, leading to decreased crop yields. Here we develop a novel approach for mapping the spatial distribution of complete topsoil loss in agricultural landscapes, focusing on the Midwestern U.S. We used the ferric iron index (FeI) derived from high-resolution satellite imagery to map Fe-rich subsoil exposed by the loss of carbon-rich topsoil. Integrating topographic curvature derived from high resolution topographic data with FeI values demonstrates that FeI values are lowest in concave hollows where eroded soil accumulates, and increase linearly with topographic curvature on convex hilltops. The relationship between FeI and curvature indicates diffusion-like erosion by tillage is a dominant mechanism of soil loss, a mechanism generally not included in soil loss prediction in the U.S. Moreover, the FeI and curvature data indicate SOC-rich topsoil has been completely removed from hilltops, exposing Fe-rich subsoil. This interpretation supported by measurements of FeI using laboratory spectra, extractable-Fe, and organic C from two soil profiles from native prairies, which preserve the pre-agricultural soil profile. FeI increased sharply from the topsoil through the subsoil and total C and extractable Fe content are negatively correlated in both profiles. We calculated topographic curvature for 3.8 x105 km2 of the formerly-glaciated Midwestern U.S. using LiDAR data and found that convex topography, where FeI values suggest topsoil has been completely stripped, covers half of the landscape. Assuming complete removal of original SOC on all hilltops, we estimate that 784 Tg of C has been removed since cultivation began in the mid-1800s and that the SOC decline results in billions of dollars in annual economic losses from decreased crop yields. Restoration of eroded SOC has been proposed as a method to sequester atmospheric CO2 while simultaneously increasing crop yields, and our estimates suggest that replenishing eroded SOC within the Midwestern U.S. to pre-settlement levels could sequester 2900 Tg of CO2, equivalent to more than half of 2016 U.S. CO2 emissions. Our study highlights both the necessity to incorporate tillage into soil erosion models and the potential for SOC restoration to increase crop yields and offset carbon emissions.

Molecular differentiation of subsoil biopores of different origin by PLFA analysis

NASA Astrophysics Data System (ADS)

Banfield, Callum; Pausch, Johanna; Kuzyakov, Yakov

2015-04-01

Biologically generated macropores (biopores) are a key factor for propagation of root growth, nutrient mobilisation and acquisition from the subsoil. However, biopores of different origin, i.e. root-derived, earthworm-derived or of mixed origin, are difficult to distinguish visually in the field. Therefore, the objective of this study was to test molecular differentiation by means of phospholipds fatty acids (PLFA). 24 samples of biopore content of the three aforementioned origins and 8 bulk soil samples were taken from two soil depths (45 - 75 cm; 75 - 105 cm) and extracted twice by a solution of methanol, chloroform and citrate/KOH buffer (pH 4, v:v:v = 1:2:0.8). Following separation of phospholipids, derivatisation was by hydrolysation using NaOH in MeOH and methylation by adding BF3 and heating at 80°C. After further purification and preparation, samples were measured by gas chromatography - mass spectrometry (GC-MS). Generally, the abundance of PLFA differed only slightly between the upper and lower soil depth. Gram negative bacteria (16:1w7c, 18:1w7c and Cy17:0) were the most abundant microbial group in both depths and show clear enrichment in biopores, especially in the mixed-pore type. A similiar pattern was observed for fungi (18:2w6,9), but it was less pronounced in the deeper section. Actinomycetes (10Me16:0 and 10Me18:0) in contrast, show the highest enrichment in root-derived pores. Interestingly, highest abundance of AM fungi (16:1w5c) was found not in root-derived pores, but in the mixed-pore type. Protozoa (20:4w6) occured significantly higher in the earthworm-derived biopores. The majority of the gram positive bacteria (a15:0, i15:0, i17:0 and a17:0) showed no significant preference of habitat, i.e. in this case pore type or bulk soil. This is indicative for general decomposers of old soil organic matter. Thus we showed, that PLFA analysis not only a valuable molecular proxy for the differentiation of biopore types, but also provides deep insight into the role of individual microbial functional groups in nutrient mobilisation and cycling in subsoils.

Landforms of the United States

USGS Publications Warehouse

Hack, John T.

1969-01-01

The United States contains a great variety of landforms which offer dramatic contrasts to a crosscountry traveler. Mountains and desert areas, tropical jungles and areas of permanently frozen subsoil, deep canyons and broad plains are examples of the Nation's varied surface. The present-day landforms the features that make up the face of the earth are products of the slow, sculpturing actions of streams and geologic processes that have been at work throughout the ages since the earth's beginning.

Landforms of the United States

USGS Publications Warehouse

Hack, John T.

1988-01-01

The United States contains a great variety of landforms which offer dramatic contrasts to a cross-country traveler. Mountains and desert areas, tropical jungles and areas of permanently frozen subsoil, and deep canyons and broad plains are examples of the Nation's varied surface. The presentday landforms the features that make up the face of the Earth are products of the slow sculpturing actions of streams and geologic processes that have been at work throughout the ages since the Earth's beginning.

Environmental Assessment, United States Air Force Proposed Lease Replacement for Scandia Elementary School, Travis Air Force Base, California

DTIC Science & Technology

2015-09-01

brown, and light gray loam 19-inches thick. The subsoil is mottled, light yellowish brown, yellowish brown, and pale brown clay 41-inches thick...areas of Solano loam and Pescadero clay loam. The Antioch soil has slightly concave slopes, and the San Ysidro soil has slightly convex slopes (Web...Infrastructure and utilities include transportation, water supply, sanitary sewage/wastewater natural gas, electrical, communications, and liquid fuels

Installation Restoration Program Records Search for Mountain Home Air Force Base, Idaho.

DTIC Science & Technology

1983-07-01

ornamental plantings. Mammals found on and around the base include coyote, black-tailed jackrabbit, cottontail, Franklin’s ground squirrel, and yellow - bellied ...Water Well Location Map. ::HILLI L - -- - • Depthin Feet Natural Ground Level Top Soil & Yellow Clay Subsoil Grey Basalt Rock-Medium Hardi30" Casing Grey... marmot as well as several varieties of small rodents. Birds which commonly nest on the base include American robin, house finch, English sparrow

Phytoextraction of heavy metals from contaminated soil by co-cropping with chelator application and assessment of associated leaching risk.

PubMed

Wei, Z B; Guo, X F; Wu, Q T; Long, X X; Penn, C J

2011-08-01

Phytoextraction using hyperaccumulating plants is generally time-consuming and requires the cessation of agriculture. We coupled chelators and a co-cropping system to enhance phytoextraction rates, while allowing for agricultural production. An experiment on I m3 lysimeter beds was conducted with a co-cropping system consisting of the hyperaccumulator Sedum alfredii and low-accumulating corn (Zea Mays, cv. Huidan-4), with addition ofa mixture of chelators (MC), to assess the efficiency of chelator enhanced co-crop phytoextraction and the leaching risk caused by the chelator. The results showed that the addition of MC promoted the growth of S. alfredii in the first crop (spring-summer season) and significantly increased the metal phytoextraction. The DTPA-extractable and total metal concentrations in the topsoil were also reduced more significantly with the addition of MC compared with the control treatments. However, mono-cropped S. alfredii without MC was more suitable for maximizing S. alfredii growth and therefore phytoextraction of Zn and Cd during the autumn-winter seasons. No adverse impact to groundwater due to MC application was observed during the experiments with three crops and three MC applications. But elevated total Cd and Pb concentrations among subsoils compared to the initial subsoil concentrations were found for the co-crop + MC treatment after the third crop.

Subsoil TPH and other petroleum fractions-contamination levels in an oil storage and distribution station in north-central Mexico.

PubMed

Iturbe, Rosario; Flores, Carlos; Flores, Rosa Ma; Torres, Luis G

2005-12-01

Many oil industry related sites have become contaminated due to the activities characteristic of this industry, such as oil exploration and production, refining, and petro-chemistry. In Mexico, reported hydrocarbon spills for the year 2000 amounted to 185203, equivalent to 6252 tons (PEMEX, 2000). The first step for the remediation of these polluted sites is to assess the size and intensity of the oil contamination affecting the subsoil and groundwater, followed by a health risk assessment to establish clean up levels. The aim of this work was to characterize the soil and water in a north-central Mexico Oil Storage and Distribution Station (ODSS), in terms of TPHs, gasoline and diesel fractions, BTEX, PAHs, MTBE, and some metals. Besides, measurements of the explosivity index along the ODSS were made and we describe and discuss the risk health assessment analysis performed at the ODSS, as well as the recommendations arising from it. Considering soils with TPH concentrations higher than 2000 mg kg(-1), the contaminated areas corresponding to the railway zone is about 12776.5 m2, to the south of the storage tanks is about 6558 m2, and to the south of the filling tanks is about 783 m2. Total area to be treated is about 20107 m2 (volume of 20107 m3), considering 1m depth.

Improving root-zone soil properties for Trembling Aspen in a reconstructed mine-site soil

NASA Astrophysics Data System (ADS)

Dyck, M. F.; Sabbagh, P.; Bockstette, S.; Landhäusser, S.; Pinno, B.

2014-12-01

Surface mining activities have significantly depleted natural tree cover, especially trembling aspen (Populus tremuloides), in the Boreal Forest and Aspen Parkland Natural Regions of Alberta. The natural soil profile is usually destroyed during these mining activities and soil and landscape reconstruction is typically the first step in the reclamation process. However, the mine tailings and overburden materials used for these new soils often become compacted during the reconstruction process because they are subjected to high amounts of traffic with heavy equipment. Compacted soils generally have low porosity and low penetrability through increased soil strength, making it difficult for roots to elongate and explore the soil. Compaction also reduces infiltration capacity and drainage, which can cause excessive runoff and soil erosion. To improve the pore size distribution and water transmission, subsoil ripping was carried out in a test plot at Genesee Prairie Mine, Alberta. Within the site, six replicates with two treatments each, unripped (compacted) and ripped (decompacted), were established with 20-m buffers between them. The main objective of this research was to characterize the effects of subsoil ripping on soil physical properties and the longevity of those effects.as well as soil water dynamics during spring snowmelt. Results showed improved bulk density, pore size distribution and water infiltration in the soil as a result of the deep ripping, but these improvements appear to be temporary.

On-site infiltration of road runoff using pervious pavements with subjacent infiltration trenches as source control strategy.

PubMed

Fach, S; Dierkes, C

2011-01-01

The focus in this work was on subsoil infiltration of stormwater from parking lots. With regard to operation, reduced infiltration performance due to clogging and pollutants in seepage, which may contribute to contaminate groundwater, are of interest. The experimental investigation covered a pervious pavement with a subjacent infiltration trench draining an impervious area of 2 ha. In order to consider seasonal effects on the infiltration performance, the hydraulic conductivity was measured tri-monthly during monitoring with a mobile sprinkling unit. To assess natural deposits jointing, road bed, gravel of infiltration trenches and subsoil were analysed prior to commencement of monitoring for heavy metals, polycyclic aromatic and mineral oil type hydrocarbons. Furthermore, from 22 storm events, water samples of rainfall, surface runoff, seepage and ground water were analysed with regard to the above mentioned pollutants. The study showed that the material used for the joints had a major impact on the initial as well as the final infiltration rates. Due to its poor hydraulic conductivity, limestone gravel should not be used as jointing. Furthermore, it is recommended that materials for the infiltration facilities are ensured free of any contaminants prior to construction. Polycyclic aromatic and mineral oil type hydrocarbons were, with the exception of surface runoff, below detection limits. Heavy metal concentrations of groundwater were with the exception of lead (because of high background concentrations), below the permissible limits.

Soil retention of hexavalent chromium released from construction and demolition waste in a road-base-application scenario.

PubMed

Butera, Stefania; Trapp, Stefan; Astrup, Thomas F; Christensen, Thomas H

2015-11-15

We investigated the retention of Cr(VI) in three subsoils with low organic matter content in laboratory experiments at concentration levels relevant to represent leachates from construction and demolition waste (C&DW) reused as unbound material in road construction. The retention mechanism appeared to be reduction and subsequent precipitation as Cr(III) on the soil. The reduction process was slow and in several experiments it was still proceeding at the end of the six-month experimental period. The overall retention reaction fit well with a second-order reaction governed by actual Cr(VI) concentration and reduction capacity of the soil. The experimentally determined reduction capacities and second-order kinetic parameters were used to model, for a 100-year period, the one-dimensional migration of Cr(VI) in the subsoil under a layer of C&DW. The resulting Cr(VI) concentration would be negligible below 7-70 cm depth. However, in rigid climates and with high water infiltration through the road pavement, the reduction reaction could be so slow that Cr(VI) might migrate as deep as 200 cm under the road. The reaction parameters and the model can form the basis for systematically assessing under which scenarios Cr(VI) from C&DW could lead to an environmental issue for ground- and receiving surface waters. Copyright © 2015 Elsevier B.V. All rights reserved.

Improved management of winter operations to limit subsurface contamination with degradable deicing chemicals in cold regions.

PubMed

French, Helen K; van der Zee, Sjoerd E A T M

2014-01-01

This paper gives an overview of management considerations required for better control of deicing chemicals in the unsaturated zone at sites with winter maintenance operations in cold regions. Degradable organic deicing chemicals are the main focus. The importance of the heterogeneity of both the infiltration process, due to frozen ground and snow melt including the contact between the melting snow cover and the soil, and unsaturated flow is emphasised. In this paper, the applicability of geophysical methods for characterising soil heterogeneity is considered, aimed at modelling and monitoring changes in contamination. To deal with heterogeneity, a stochastic modelling framework may be appropriate, emphasizing the more robust spatial and temporal moments. Examples of a combination of different field techniques for measuring subsoil properties and monitoring contaminants and integration through transport modelling are provided by the SoilCAM project and previous work. Commonly, the results of flow and contaminant fate modelling are quite detailed and complex and require post-processing before communication and advising stakeholders. The managers' perspectives with respect to monitoring strategies and challenges still unresolved have been analysed with basis in experience with research collaboration with one of the case study sites, Oslo airport, Gardermoen, Norway. Both scientific challenges of monitoring subsoil contaminants in cold regions and the effective interaction between investigators and management are illustrated.

Reclamation of zinc-contaminated soil using a dissolved organic carbon solution prepared using liquid fertilizer from food-waste composting.

PubMed

Chiang, Po-Neng; Tong, Ou-Yang; Chiou, Chyow-San; Lin, Yu-An; Wang, Ming-Kuang; Liu, Cheng-Chung

2016-01-15

A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zn-contaminated soil (with Zn concentrations up to 992 and 757 mg kg(-1) in topsoil and subsoil, respectively). We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution, and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid fertilizer. Two soil washes using 1,500 mg L(-1) DOC solution with a of pH 2.0 at 25°C removed about 43% and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available ammonium (NH4(+)-N) content increased to 2.4 times the original level; and in the topsoil, the available phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their initial levels, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of soil and groundwater corrosion on the Hierakonpolis Temple Town archaeological site, Wadi Abu Sufian, Idfu, Egypt.

PubMed

El-Shishtawy, A M; Atwia, M G; El-Gohary, A; Parizek, R R

2013-06-01

Hierakonpolis, Greek for City of the Hawk, nearly 25 km NW of Idfu (Egypt), is an important and extensive archaeological discovery covering a large area. Its richness in archaeological artifacts makes it a valuable site. It has a valid claim to be the first nation state, as indicated by the Palette of Narmer discovered in its main mound. Geological and hydrogeological investigations at the Hierakonpolis Temple Town site documented nearly a 4.0-m water table rise from as early as 1892 to the present. In addition to the rising water levels, the increase of both subsoil water salinity and humidity threatens and damages fragile carvings and paintings within tombs in Kingdom Hill, the foundation stability of the site, and the known and still to be discovered artifact that recent pottery finds dates at least 4,000 BCE. Representative rock and soil samples obtained from drilled cores in the study area were chosen for conducting detailed grain size and X-ray analysis, light and heavy mineral occurrences, distribution of moisture and total organic matter, and scanning electron microscopy investigations. Mineralogical analysis of clays indicated that the soil samples are composed of smectite/illite mixed layers with varying proportions of smectite to illite. Kaolinite is the second dominant clay constituent, besides occasional chlorite. Swelling of the clay portion of the soil, due to the presence of capillary groundwater, in contact with buried mudbrick walls expands and causes severe damage to important exposed and buried mudbrick structures, including the massive ancient "fort" believed to date from the Second Dynasty (from 2,890 to 2,686 BC). The "fort" is 1.0 km south of the Temple Town mounds near to confluence of Wadi Abu Sufian. Groundwater samples from the shallow aquifer close by the intersection of Wadi Abu Sufian and the Nile flood plain were analyzed for chemical composition and stable isotope ratios. The groundwater in the upper zone (subsoil water) within fine-grained Nile alluvium is characterized by high salinity which varies from 415 to 4,500 mg/L total dissolved solids. In contrast, most of the groundwater samples in the lower zone (Quaternary aquifer) are characterized by a low salinity in the order of 164-792 mg/L. Values of δD and δO(18) obtained from this deep (9-20 m) aquifer ranged from 16.98 to 19.87 ‰ and from 1.67 to 2.99 ‰, respectively. These values indicated that the Quaternary aquifer waters are recharged directly from recent Nile water. Subsoil water is very shallow in the area; it ranged from 0 to 2.6 m with a mean of 1.1 m within the main mound of the Hierakonpolis Temple Town site by 2003, in contrast to its more than 4.5-m depth in 1897. The exposure of subsoil water to increased evaporation is expected, with a consequent increase in the concentrations of dissolved solids and usually large proportions of chloride and sulfate. Artifacts recovered from the Temple Town site are becoming damaged and destroyed by crystallization processes caused by repeated wetting and drying of salt and the accumulation of new salts.

Dynamic Eigenvalue Problem of Concrete Slab Road Surface

NASA Astrophysics Data System (ADS)

Pawlak, Urszula; Szczecina, Michał

2017-10-01

The paper presents an analysis of the dynamic eigenvalue problem of concrete slab road surface. A sample concrete slab was modelled using Autodesk Robot Structural Analysis software and calculated with Finite Element Method. The slab was set on a one-parameter elastic subsoil, for which the modulus of elasticity was separately calculated. The eigen frequencies and eigenvectors (as maximal vertical nodal displacements) were presented. On the basis of the results of calculations, some basic recommendations for designers of concrete road surfaces were offered.

Final Environmental Assessment (EA) for Replacement of the Wastewater Lift Station (Building 510)

DTIC Science & Technology

2013-03-01

ensure that wastewater from FEW continues to be safely and efficiently moved to the City of Cheyenne sanitary sewer system. The lift station is...from four to six inches. The subsoil is primarily alluvial clay that extends from a depth of approximately 6 to 36 inches. 8.4. Air Quality. Under...Disposal 8.6.1. Sanitary Sewer System A National Pollutant Discharge Elimination System (NPDES) permit issued by the WYDEQ is in place to allow discharge

Environmental Assessment (EA) for Replacement of the Wastewater Lift Station (Building 510)

DTIC Science & Technology

2013-04-13

ensure that wastewater from FEW continues to be safely and efficiently moved to the City of Cheyenne sanitary sewer system. The lift station is...from four to six inches. The subsoil is primarily alluvial clay that extends from a depth of approximately 6 to 36 inches. 8.4. Air Quality. Under...Disposal 8.6.1. Sanitary Sewer System A National Pollutant Discharge Elimination System (NPDES) permit issued by the WYDEQ is in place to allow discharge

Live Site Demonstrations: Former Camp Beale Demonstration of MetalMapper Static Data Acquisition and Data Analysis

DTIC Science & Technology

2012-05-01

tilted metamorphic rock . Typically, the surface layer of the soil is a brown gravelly silt with sand, about 4 inches thick. The subsoil is yellowish red...site setup, the placement of 200 seed items for use in measuring the capabilities of the advanced EMI sensors tested, the subsequent collection of...advanced sensors. The second team was responsible for the cued survey of 1,491 of the 2,143 targets using the MetalMapper, one of the advanced

Physical parameters of Fluvisols on flooded and non-flooded terraces

NASA Astrophysics Data System (ADS)

Kercheva, Milena; Sokołowska, Zofia; Hajnos, Mieczysław; Skic, Kamil; Shishkov, Toma

2017-01-01

The heterogeneity of soil physical properties of Fluvisols, lack of large pristine areas, and different moisture regimes on non-flooded and flooded terraces impede the possibility to find a soil profile which can serve as a baseline for estimating the impact of natural or anthropogenic factors on soil evolution. The aim of this study is to compare the pore size distribution of pristine Fluvisols on flooded and non-flooded terraces using the method of the soil water retention curve, mercury intrusion porosimetry, nitrogen adsorption isotherms, and water vapour sorption. The pore size distribution of humic horizons of pristine Fluvisols on the non-flooded terrace differs from pore size distribution of Fluvisols on the flooded terrace. The peaks of textural and structural pores are higher in the humic horizons under more humid conditions. The structural characteristics of subsoil horizons depend on soil texture and evolution stage. The peaks of textural pores at about 1 mm diminish with lowering of the soil organic content. Structureless horizons are characterized by uni-modal pore size distribution. Although the content of structural pores of the subsoil horizons of Fluvisols on the non-flooded terrace is low, these pores are represented by biopores, as the coefficient of filtration is moderately high. The difference between non-flooded and flooded profiles is well expressed by the available water storage, volume and mean radius of pores, obtained by mercury intrusion porosimetry and water desorption, which are higher in the surface horizons of frequently flooded Fluvisols.

Carbon turnover in an agricultural sub-soil

NASA Astrophysics Data System (ADS)

Collins, Chris

2010-05-01

Maize was added to a grassland subsoil (10 - 50 cm) and the fate of the carbon from the plant material followed for 520 days with nine sampling points over an exponential time series. The carbon and delta 13C signature in five soil fractions: POM (particulate organic matter), fine sand, coarse silt, fine silt and clay were monitored. Over the course of the experiment there was a 57% decline in the total C of the soil principally from the particulate organic matter which contained the added maize equivalent to a half life of 533 days. A single exponential was the best fit to the data indicating that the slower turnover pools proposed in models such as Roth C were not observed in the time course of this experiment. Carbon rapidly entered the fine sand and coarse silt fractions, it then passed into the clay fraction. The fine silt fraction was not significantly changed. The maize carbon showed a delay to this pattern, but there was accumulation of maize carbon in the fine sand and fine silt fractions. The largest increases in % carbon as a consequence of the introduction of the maize carbon were of the following order clay > fine sand > coarse silt >fine silt. The results suggest that all these fractions are actively being turnover in this soil and that carbon is most protected in the fine sand and silt fractions, not clay as has been observed by other workers. The results are also discussed in the wider contexts of representative pools for modeling.

Coupled mobilization of dissolved organic matter and metals (Cu and Zn) in soil columns

NASA Astrophysics Data System (ADS)

Zhao, Lu Y. L.; Schulin, Rainer; Weng, Liping; Nowack, Bernd

2007-07-01

Dissolved organic carbon (DOC) is a key component involved in metal displacement in soils. In this study, we investigated the concentration profiles of soil-borne DOC, Cu and Zn at various irrigation rates with synthetic rain water under quasi steady-state conditions, using repacked soil columns with a metal-polluted topsoil and two unpolluted subsoils. Soil solution was collected using suction cups installed at centimeter intervals over depth. In the topsoil the concentrations of DOC, dissolved metals (Zn and Cu), major cations (Ca 2+ and Mg 2+) and anions ( NO3- and SO42-) increased with depth. In the subsoil, the Cu and Zn concentrations dropped to background levels within 2 cm. All compounds were much faster mobilized in the first 4 cm than in the rest of the topsoil. DOC and Cu concentrations were higher at higher flow rates for a given depth, whereas the concentrations of the other ions decreased with increasing flow rate. The decomposition of soil organic matter resulted in the formation of DOC, SO42-, and NO3- and was the main driver of the system. Regression analysis indicated that Cu mobilization was governed by DOC, whereas Zn mobilization was primarily determined by Ca and to a lesser extent by DOC. Labile Zn and Cu 2+ concentrations were well predicted by the NICA-Donnan model. The results highlight the value of high-resolution in-situ measurements of DOC and metal mobilization in soil profiles.

Phosphorus exchangeability and leaching losses from two grassland soils.

PubMed

Sinaj, S; Stamm, C; Toor, G S; Condron, L M; Hendry, T; Di, H J; Cameron, K C; Frossard, E

2002-01-01

Although phosphate phosphorus (P) is strongly sorbed in many soils, it may be quickly transported through the soil by preferential flow. Under flood irrigation, preferential flow is especially pronounced and associated solute losses may be important. Phosphorus losses induced by flood irrigation were investigated in a lysimeter study. Detailed soil chemical analyses revealed that P was very mobile in the topsoil, but the higher P-fixing capacity of the subsoil appeared to restrict P mobility. Application of a dye tracer enabled preferential flow pathways to be identified. Soil sampling according to dye staining patterns revealed that exchangeable P was significantly greater in preferential flow areas as compared with the unstained soil matrix. This could be partly attributed to the accumulation of organic carbon and P, together with enhanced leaching of Al- and Fe-oxides in the preferential flow areas, which resulted in reduced P sorption. The irrigation water caused a rapid hydrologic response by displacement of resident water from the subsoil. Despite the occurrence of preferential flow, most of the outflowing water was resident soil water and very low in P. In these soils the occurrence of preferential flow per se is not sufficient to cause large P losses even if the topsoil is rich in P. It appears that the P was retained in lower parts of the soil profile characterized by a very high P-fixing capacity. This study demonstrates the risks associated with assessing potential P losses on the basis of P mobility in the topsoil alone.

Environmental implications of high metal content in soils of a titanium mining zone in Kenya.

PubMed

Maina, David M; Ndirangu, Douglas M; Mangala, Michael M; Boman, Johan; Shepherd, Keith; Gatari, Michael J

2016-11-01

Mining activities contribute to an increase of specific metal contaminants in soils. This may adversely affect plant life and consequently impact on animal and human health. The objective of this study was to obtain the background metal concentrations in soils around the titanium mining in Kwale County for monitoring its environmental impacts. Forty samples were obtained with half from topsoils and the other from subsoils. X-ray fluorescence spectrometry was used to determine the metal content of the soil samples. High concentrations of Ti, Mn, Fe, and Zr were observed where Ti concentrations ranged from 0.47 to 2.8 %; Mn 0.02 to 3.1 %; Fe 0.89 to 3.1 %; and Zr 0.05 to 0.85 %. Using ratios of elemental concentrations in topsoil to subsoil method and enrichment factors concept, the metals were observed to be of geogenic origin with no anthropogenic input. The high concentrations of Mn and Fe may increase their concentration levels in the surrounding agricultural lands through deposition, thereby causing contamination on the land and the cultivated food crops. The latter can cause adverse human health effects. In addition, titanium mining will produce tailings containing low-level titanium concentrations, which will require proper disposal to avoid increasing titanium concentrations in the soils of the region since it has been observed to be phytotoxic to plants at high concentrations. The results of this study will serve as reference while monitoring the environmental impact by the titanium mining activities.

Evaluation of carbon saturation across gradients of cropping systems diversity and soil depth

NASA Astrophysics Data System (ADS)

Castellano, Michael; Poffenbarger, Hanna; Cambardella, Cindy; Liebman, Matt; Mallarino, Antonio; Olk, Dan; Russell, Ann; Six, Johan

2017-04-01

Growing evidence indicates arable soils in the US Maize Belt are effectively carbon-saturated. We hypothesized that: 1) surface soil mineral-associated soil organic carbon (SOC) stocks in these systems are effectively carbon-saturated and 2) diverse cropping systems with greater belowground C inputs would increase subsoil SOC stocks because subsoils have large C saturation deficit. Using three long-term field trials in Iowa (study durations of 60, 35, and 12 years), we examined the effects of cropping system diversity (maize-soybean-oat/alfalfa-alfalfa or corn-corn-oat/alfalfa-alfalfa vs. maize-soybean rotation) on SOC content at different depths (0-100 cm) throughout the soil profile. Average annual C inputs were similar for both cropping systems, but the proportion of C delivered belowground was approximately twice as great in the extended rotations. Within and across cropping systems and the three field trial locations, there was a positive linear relationship between total SOC and the concentration of SOC in the mineral-associated fraction, indicating mineral-associated SOC stocks are not saturated. Organic C accumulation was observed at depth (15-100 cm) but not at the surface (0-15 cm) across all sites and rotations. These data suggest surface SOC stocks may have reached equilibrium rather than effective C saturation. In the absence of experiments that manipulate C inputs, the relationship between total SOC and the concentration of SOC in the mineral-associated fraction is frequently used as a proxy for C-saturation, and this relationship should be further explored.

Humanitarian IED clearance in Colombia

NASA Astrophysics Data System (ADS)

Hendrickx, J. M. H.; Molina, A.; Diaz, D.; Grasmueck, M.; Moreno, H. A.; Hernández, R. D.

2008-04-01

The development of Improvised Explosive Devices (IED's) by insurgents in Colombia is characterized by a quick response to counter IED measures. Many current IED's do not contain any metal parts and can have any shape or form. Due to the low metal content or the absence of any metal parts, sensors based on metal detection are not useful anymore. Due to the wide variety of sizes, shapes, and enclosure materials of current IED's, one and two-dimensional GPR sensors using a "library" of known shapes as well as acoustic sensors using material characteristic frequencies have become ineffective. Therefore, the Colombian experience strongly suggests that chemical sensors are the way for IED detection in soils since they do not depend on IED metal content, size, or shape but only on the presence of explosives, a necessary ingredient for any IED. Promising recently developed chemical sensors make use of semiconducting organic polymers (SOPs) such as FIDO and laser-induced breakdown spectroscopy (LIBS). Once an explosive has been detected, the IED needs to be identified and located. Therefore, there is a need for three-dimensional high resolution scans for identification of all subsoil features including rocks, roots, and IED's. The recently developed 3D-GPR (Ground Penetrating Radar) can map all features of the subsoil with a spatial resolution of about 2 cm or less. The objectives of this contribution are to inform about the IED problem in Colombia and how novel technologies may contribute to humanitarian IED clearance under humid tropical conditions.

Residual effects of EDDS leachates on plants during EDDS-assisted phytoremediation of copper contaminated soil.

PubMed

Yang, Li; Luo, Chunling; Liu, Yue; Quan, Lingtong; Chen, Yahua; Shen, Zhenguo

2013-02-01

In this study, a novel experimental setup (one pot placed above another) was used to investigate the residual effects of EDDS application on plant growth and metal uptake. Two plant species, garland chrysanthemum and ryegrass, were grown in the upper pots (mimicking the upper soil layers) and were harvested 7 days after EDDS application. During this period the upper pots were watered twice. The lower pots (mimicking the subsoil under the upper soil layers) served as leachate collectors. Thereafter, the two pots were separated, and the same plants were grown in the upper and lower pots in two continuous croppings. Results showed that EDDS application restrained the growth of the first crop and resulted in a dramatic enhancement of Cu accumulation in plants grown in the upper pots. However, no negative growth effects were identified for the second and third crops, which were harvested 81 and 204 days after the EDDS application, respectively. In the lower pots, the leachate from the upper pots after EDDS application exhibited the increased total and CaCl(2)-extractable Cu concentrations in the soil. However, the growth of garland chrysanthemum and ryegrass, and their shoot Cu concentrations were unaffected. These data suggest that the residual risk associated with EDDS application was limited, and that subsoil to which EDDS leachate was applied may exhibit reduced Cu bioavailability for plants due to the biodegradation of EDDS. Copyright © 2012 Elsevier B.V. All rights reserved.

[Effects of tillage rotation and fertilization on soil aggregates and organic carbon content in corn field in Weibei Highland].

PubMed

Wang, Li; Li, Jun; Li, Juan; Bai, Wei-Xia

2014-03-01

A field experiment on effects of tillage rotation and fertilization on corn continuous cropping-practiced lands was carried out in Heyang of Shaanxi in 2007-2012. The tillage types included annual rotation of no-tillage and subsoiling (NT-ST), subsoiling and conventional tillage (ST-CT), or conventional tillage and no-tillage (CT-NT), and yearly practice of no tillage (NT-NT), subsoiling (ST-ST) or conventional tillage (CT-CT). The fertilization treatments included balanced fertilization, low-rate fertilization and conventional fertilization, which were separately practiced against the different tillage types. The experiment investigated compositions, mean mass diameters (MWD), geometrical mean diameters (GMD) and fraction dimension numbers (D) of soil aggregates in 0-40 cm soil and contents of organic carbon in 0-60 cm soil. The results indicated that: 1) The increased tillage intensity caused the reduced mechanical stability and content of soil aggregates and increased soil organic carbon loss. No-tillage or tillage rotation increased the MWD, GMD and contents of soil organic carbon and soil aggregates with diameters of more than 0.25 mm, but decreased D. Under the same fertilization treatment, the contents of soil aggregates with diameters of more than 0.25 mm were ranked in the order of NT-NT>NT-ST>NT-CT>ST-ST>CT-ST>CT-CT, and under the same tillage rotations, the soil aggregates were more stable with the balanced or low- rate fertilization than with the conventional fertilization. 2) Mathematical fractal dimension fitting of soil aggregates indicated that the fractal dimension numbers of soil aggregates ranged within 2.247-2.681 by dry sieving and 2.897-2.976 by wet sieving. In 0-30 cm soil, the fractal dimension numbers of soil aggregates were significantly lower under no-tillage or tillage rotation than under conventional tillage, and in 0-40 cm soil, the fractal dimensions of soil aggregates increased with soil depth, and tended to stabilize at the soil depth of 40 cm. 3) The different fertilization treatments exerted significantly different influences on the contents of soil organic carbon (P < 0.05), which tended to decline with soil depth. Compared to the conventional fertilization, the balanced fertilization increased the content of soil organic carbon by 6.9%, and the contents of soil organic carbon increased as the diameters of soil aggregates increased. The correlation analysis showed that the contents of soil aggregates with diameters of 0.25-2 mm significantly affected the content of soil organic carbon, with the coefficient of determination being 0.848 (P < 0.01).

Mineral weathering experiments to explore the effects of vegetation shifts in high mountain region (Wind River Range, Wyoming, USA)

NASA Astrophysics Data System (ADS)

Mavris, Christian; Furrer, Gerhard; Dahms, Dennis; Anderson, Suzanne P.; Blum, Alex; Goetze, Jens; Wells, Aaron; Egli, Markus

2015-04-01

Climate change influences the evolution of soil and landscape. With changing climate, both flora and fauna must adapt to new conditions. It is unknown in many respects to what extent soils will react to warming and vegetation change. The aim of this study was to identify possible consequences for soils in a dry-alpine region with respect to weathering of primary minerals and leaching of elements under expected warming climate conditions due to shifts in vegetation. To achieve this, a field empirical approach was used in combination with laboratory weathering experiments simulating several scenarios. Study sites located in Sinks Canyon and in Stough Basin of the Wind River Range, Wyoming, USA, encompass ecotones that consist of tundra, forest, or sagebrush (from moist to dry, with increasing temperature, respectively). All soils are developed on granitoid moraines. The mineralogy of the soils along the altitudinal sequence was analysed using cathodoluminescence and X-ray diffraction, and revealed clear mineral transformations: biotite and plagioclase were both weathered to smectite while plagioclase also weathered to kaolinite. Cooler, wetter, altitude-dependent conditions seemed to promote weathering of these primary minerals. To test the impact of soil solutions from different ecotones on mineral weathering, aqueous extracts from topsoils (A horizons) were reacted with subsoils (B horizons) in batch experiments. Aqueous extracts of topsoil samples were generated for all three ecotones, and these solutions were characterized. For the batch experiments, the topsoil extracts were reacted for 1800 hours with the subsoil samples of the same ecotone, or with the subsoil samples from higher altitude ecotones. Solutions collected periodically during the experiments were measured using ICP-OES and ion chromatography. Dissolved Ca, Mg and K were mainly controlled by the chemical weathering of oligoclase, K-feldspar and biotite. With increasing altitude (and consequently cooler and moister climate) the total concentrations of Ca, Mg and K in the aqueous extracts decreased, the relative ionic contribution by K decreased, while the ionic contribution by Ca increased. Thus, a shift in vegetation due to climate change seems to affect the ionic composition - but not the ionic load - of the soil solution. In the case of a shift from forest - to - sagebrush and tundra - to - forest or sagebrush, the relative contribution by K strongly increases at the expense of Ca. We hypothesize that K should play an important role in future biogeochemical cycles under the assumptions of climate warming and subsequent vegetation shifts to higher altitudes.

Evidence on Anaerobic Methane Oxidation (AOM) in a boreal cultivated peatland with natural and added electron acceptors

NASA Astrophysics Data System (ADS)

Dorodnikov, Maxim; Silvennoinen, Hanna; Martikainen, Pertti; Dörsch, Peter

2015-04-01

Anaerobic oxidation of methane (AOM) is a process of methane (CH4) consumption under anoxic conditions driven by microorganisms, which oxidize CH4 with various alternate electron acceptors (AEA): sulfate, nitrate, nitrite, metals-(Fe, Mn, Cu), organic compounds. AOM is common in marine ecosystems, where microbial sulfate reduction (SR) consumes most of the CH4 produced in sediments. Despite the global significance of AOM, the exact mechanisms and relevance of the process in terrestrial ecosystems are almost unknown. In the current study the occurrence of AOM was tested for two organic soil horizons (30 and 40 cm depth) and one mineral sub-soil (sand, 50 cm depth) of a cultivated boreal peatland (Linnansuo, Eastern Finland, energy crop Phalaris arundinacea - reed canarygrass) under controlled conditions with the addition of 13C-labeled CH4 and two common AEAs - SO4-2 and Fe+3. Concentrations of CH4, CO2 and O2 were continuously measured during 10 days of incubation and CO2 was sampled periodically under anaerobic conditions for stable 13C analysis. Oxygen dynamics revealed negligible O2 contamination during incubation and its trace amounts (0.05-0.8% from the atmospheric) were accounted in the net CH4 uptake. Application of 13C-enriched CH4 (4.9 atom%) allowed to track the label in CO2 as the end-product of AOM. The highest 13CO2 enrichment (up to 60‰) was observed in mineral sub-soil, however AOM was quantitatively more pronounced in the upper 30 cm horizon (2.1 vs. 0.2 μg CO2 g soil DW-1 in the 50 cm sub-soil). The highest AOM rate of 8.9 ng CO2 g soil DW-1 h-1 was estimated for the control treatment where no AEAs were added indicating sufficient amount of naturally available AEAs, likely organic compounds. This rate was 50 times more intensive (on the C basis) than the CH4 production potential of the same soil. In contrast, external AEAs decreased AOM rates but added Fe+3 stimulated decomposition of native SOM (as seen from the most depleted 13CO2 signatures). Thus, the experiments revealed that this organic soil had capacity for AOM with its natural electron acceptors. Further AOM assessments may change the existing concept of carbon/CH4 cycling in terrestrial ecosystems and will improve current process-based models of regional and global carbon balance.

[Effects of different tillage patterns on soil properties, maize yield and water use efficiency in Weibei Highland, China.

PubMed

Liu, Dan; Zhang, Xia; Li, Jun; Wang, Xu-Dong

2018-02-01

An eight-year field experiment of straw returning was conducted on dark loessial soil in Weibei Highland to investigate the effects of tillage patterns on soil aggregate, soil organic carbon (SOC), corn yield and soil water use efficiency (WUE). There were six tillage patterns, including conventional tillage (CT/CT), no-tillage (NT/NT), subsoiling tillage (ST/ST), no-tillage/subsoiling tillage (NT/ST), conventional tillage/no-tillage (CT/NT) and conventional tillage/subsoiling tillage (CT/ST). The results showed that compared with CT/CT, the patterns of NT/NT, ST/ST and the rotational tillage patterns (NT/ST, CT/NT and CT/ST) decreased the mean mass diameter of soil mechanical stable aggregate. The patterns of NT/NT, ST/ST and NT/ST increased the content of soil water-stable aggregate with the particle size >0.25 mm (WR 0.25 ) and their mean mass diameter, especially in the depth of 20-50 cm. These patterns reduced the proportion of aggregate destruction (PAD). Compared with CT/CT, the patterns of NT/ST, CT/NT, NT/NT and ST/ST increased the content of SOC in 0-10 cm soil layer. The content of SOC decreased as the increases of soil depth for all tillage patterns, but the decrease in SOC of three single tillage patterns (ST/ST, NT/NT and CT/CT) was larger than that of three rotational tillage patterns. Compared with CT/CT, the other five tillage patterns increased soil water storage in 0-200 cm soil profile, crop yield and WUE in maize. The yield and WUE in NT/ST pattern were significantly increased by 15.1% and 27.5%, respectively. Both corn yield and WUE were significantly and positively correlated with soil water storage in 0-200 cm soil profile in field during the cropping and fallow periods. Moreover, soil water storage during the cropping period was positively correlated with WR 0.25 , but negatively correlated with PAD in 0-50 cm soil layer. Particularly, maize yield, WUE and soil water storage during the cropping period were closely related to WR 0.25 in 20-50 cm soil layer and PAD. Both WUE and soil water storage during the cropping period was correlated with the SOC content in 0-10 cm soil layer. With respect to the soil properties, crop yield and WUE, the tillage pattern of NT/ST was the best stratety in dark loessial soil for spring maize growth in Weibei Highland.

Strain measurements by fiber Bragg grating sensors for in situ pile loading tests

NASA Astrophysics Data System (ADS)

Schmidt-Hattenberger, Cornelia; Straub, Tilmann; Naumann, Marcel; Borm, Günter; Lauerer, Robert; Beck, Christoph; Schwarz, Wolfgang

2003-07-01

A fiber Bragg grating (FBG) sensor network has been installed into a large diameter concrete pile on a real construction site. The intention was to monitor its deformation behavior during several quasi-static loading cycles. The skin friction between pile and subsoil affecting the ultimate bearing capacity of the pile as well as the settlement behavior of the structure under investigation has been derived from our measurements. A comparison between the results of the fiber Bragg grating sensors and conventional concrete strain gages (CSG) has shown excellent correspondence.

Laboratory-scale evaluation of a combined soil amendment for the enhanced biodegradation of propylene glycol-based aircraft de-icing fluids.

PubMed

Libisch, Balázs; French, Helen K; Hartnik, Thomas; Anton, Attila; Biró, Borbála

2012-01-01

A combined soil amendment was tested in microcosm experiments with an aim to enhance the aerobic biodegradation of propylene glycol (PG)-based aircraft de-icing fluids during and following the infiltration of contaminated snowmelt. A key objective under field conditions is to increase degradation of organic pollutants in the surface soil where higher microbial activity and plant rhizosphere effects may contribute to a more efficient biodegradation of PG, compared to subsoil ground layers, where electron acceptors and nutrients are often depleted. Microcosm experiments were set up in Petri dishes using 50 g of soil mixed with appropriate additives. The samples contained an initial de-icing fluid concentration of 10,000 mg/kg soil. A combined amendment using calcium peroxide, activated carbon and 1 x Hoagland solution resulted in significantly higher degradation rates for PG both at 4 and 22 degrees C. Most probable numbers of bacteria capable of utilizing 10,000 mg/kg de-icing fluid as a sole carbon source were about two orders of magnitude higher in the amended soil samples compared to unamended controls at both temperatures. The elevated numbers of such bacteria in surface soil may be a source of cells transported to the subsoil by snowmelt infiltration. The near-surface application of amendments tested here may enhance the growth of plants and plant roots in the contaminated area, as well as microbes to be found at greater depth, and hence increase the degradation of a contaminant plume present in the ground.

Numerical Modelling of Foundation Slabs with use of Schur Complement Method

NASA Astrophysics Data System (ADS)

Koktan, Jiří; Brožovský, Jiří

2017-10-01

The paper discusses numerical modelling of foundation slabs with use of advanced numerical approaches, which are suitable for parallel processing. The solution is based on the Finite Element Method with the slab-type elements. The subsoil is modelled with use of Winklertype contact model (as an alternative a multi-parameter model can be used). The proposed modelling approach uses the Schur Complement method to speed-up the computations of the problem. The method is based on a special division of the analyzed model to several substructures. It adds some complexity to the numerical procedures, especially when subsoil models are used inside the finite element method solution. In other hand, this method makes possible a fast solution of large models but it introduces further problems to the process. Thus, the main aim of this paper is to verify that such method can be successfully used for this type of problem. The most suitable finite elements will be discussed, there will be also discussion related to finite element mesh and limitations of its construction for such problem. The core approaches of the implementation of the Schur Complement Method for this type of the problem will be also presented. The proposed approach was implemented in the form of a computer program, which will be also briefly introduced. There will be also presented results of example computations, which prove the speed-up of the solution - there will be shown important speed-up of solution even in the case of on-parallel processing and the ability of bypass size limitations of numerical models with use of the discussed approach.

Revegetation of high zinc and lead tailings with municipal biosolids and lime: greenhouse study.

PubMed

Svendson, Alex; Henry, Chuck; Brown, Sally

2007-01-01

Acidic (pH 4.1) and high Cd, Pb, and Zn mine tailings (mean +/- SD: 17 +/- 0.4, 3800 +/- 100, and 3500 +/- 100 mg kg(-1), respectively) from an alluvial tailings deposit in Leadville, Colorado were amended with municipal biosolids (BS) (224 Mg ha(-1)) and different types of lime (calcium carbonate equivalent of 224 Mg ha(-1) CaCO3) in a greenhouse column study to test the ability of the amendments to neutralize surface and subsoil acidity and restore plant growth. The types of lime included coarse, agricultural, and fine-textured lime (CL, AL, and FL), sugar beet lime (SBL), and lime kiln dust (LK). The FL was also added alone. All treatments increased bulk pH in the amended horizon in comparison to the control, with the most significant increases observed in the FL, SBL+BS, and LK+BS treatments (7.33, 7.34, and 7.63, respectively). All treatments, excluding the FL, increased the pH in the horizon directly below the amended layer, with the most significant increases observed in the SBL+BS and LK+BS treatments (6.01 and 5.41, respectively). Significant decreases in 0.01 M Ca(NO3)2-extractable Zn and Cd were observed in the subsoil for all treatments that included BS, with the largest decrease in the SBL+BS treatment (344 and 3.9 versus 4 and 0.1 mg kg(-1) Zn and Cd, respectively). Plant growth of annual rye (Lolium multiflorum L.) was vigorous in all treatments that included BS with plant Zn, Cd, and Pb concentrations reduced over the control.

[Study on mechanism of SOM stabilization of paddy soils under long-term fertilizations].

PubMed

Luo, Lu; Zhou, Ping; Tong, Cheng-Li; Shi, Hui; Wu, Jin-Shui; Huang, Tie-Ping

2013-02-01

Fourier transform infrared spectroscopy (FTIR) was applied to study the structure of soil organic matter (SOM) of paddy soils under long-term different fertilization treatments. The aim was to clarify the different distribution of SOM between different fertilization methods and between topsoil and subsoil, and to explore the stability mechanism of SOM under different fertilization treatments. The results showed that the content of topsoil organic carbon (SOC) was the highest under organic-inorganic fertilizations, with the increment of SOC by 18.5%, 12.9% and 18.4% under high organic manure (HOM), low organic manure (LOM) and straw returning (STW) respectively compared with no fertilization treatment (CK). The long-term fertilizations also changed the chemical structure of SOM. As compared with CK, different fertilization treatments increased the functional group absorbing intensity of chemical resistance compounds (aliphatic, aromaticity), carbohydrate and organo-silicon compounds, which was the most distinctive under treatments of HOM, LOM and STW. For example, the absorbing intensity of alkyl was 0.30, 0.25 and 0.29 under HOM, LOM and STW, respectively. These values were increased by 87% , 56% and 81% as compared with that under CK treatment. The functional group absorbing intensity of SOM in the topsoil was stronger than that in the subsoil, with the most distinctive difference under HOM, LOM and STW treatments. The present research indicated that the enhanced chemical resistance of functional group of SOM may contribute to the high contents of SOC in the paddy soils under long-term organic-inorganic fertilizations, which also suggested a chemical stabilization mechanism of SOM in the paddy soils.

Groundwater source contamination mechanisms: Physicochemical profile clustering, risk factor analysis and multivariate modelling

NASA Astrophysics Data System (ADS)

Hynds, Paul; Misstear, Bruce D.; Gill, Laurence W.; Murphy, Heather M.

2014-04-01

An integrated domestic well sampling and "susceptibility assessment" programme was undertaken in the Republic of Ireland from April 2008 to November 2010. Overall, 211 domestic wells were sampled, assessed and collated with local climate data. Based upon groundwater physicochemical profile, three clusters have been identified and characterised by source type (borehole or hand-dug well) and local geological setting. Statistical analysis indicates that cluster membership is significantly associated with the prevalence of bacteria (p = 0.001), with mean Escherichia coli presence within clusters ranging from 15.4% (Cluster-1) to 47.6% (Cluster-3). Bivariate risk factor analysis shows that on-site septic tank presence was the only risk factor significantly associated (p < 0.05) with bacterial presence within all clusters. Point agriculture adjacency was significantly associated with both borehole-related clusters. Well design criteria were associated with hand-dug wells and boreholes in areas characterised by high permeability subsoils, while local geological setting was significant for hand-dug wells and boreholes in areas dominated by low/moderate permeability subsoils. Multivariate susceptibility models were developed for all clusters, with predictive accuracies of 84% (Cluster-1) to 91% (Cluster-2) achieved. Septic tank setback was a common variable within all multivariate models, while agricultural sources were also significant, albeit to a lesser degree. Furthermore, well liner clearance was a significant factor in all models, indicating that direct surface ingress is a significant well contamination mechanism. Identification and elucidation of cluster-specific contamination mechanisms may be used to develop improved overall risk management and wellhead protection strategies, while also informing future remediation and maintenance efforts.

Quantitative Interpretation of Tracks for Determination of Body Mass

PubMed Central

Schanz, Tom; Lins, Yvonne; Viefhaus, Hanna; Barciaga, Thomas; Läbe, Sashima; Preuschoft, Holger; Witzel, Ulrich; Sander, P. Martin

2013-01-01

To better understand the biology of extinct animals, experimentation with extant animals and innovative numerical approaches have grown in recent years. This research project uses principles of soil mechanics and a neoichnological field experiment with an African elephant to derive a novel concept for calculating the mass (i.e., the weight) of an animal from its footprints. We used the elephant's footprint geometry (i.e., vertical displacements, diameter) in combination with soil mechanical analyses (i.e., soil classification, soil parameter determination in the laboratory, Finite Element Analysis (FEA) and gait analysis) for the back analysis of the elephant's weight from a single footprint. In doing so we validated the first component of a methodology for calculating the weight of extinct dinosaurs. The field experiment was conducted under known boundary conditions at the Zoological Gardens Wuppertal with a female African elephant. The weight of the elephant was measured and the walking area was prepared with sediment in advance. Then the elephant was walked across the test area, leaving a trackway behind. Footprint geometry was obtained by laser scanning. To estimate the dynamic component involved in footprint formation, the velocity the foot reaches when touching the subsoil was determined by the Digital Image Correlation (DIC) technique. Soil parameters were identified by performing experiments on the soil in the laboratory. FEA was then used for the backcalculation of the elephant's weight. With this study, we demonstrate the adaptability of using footprint geometry in combination with theoretical considerations of loading of the subsoil during a walk and soil mechanical methods for prediction of trackmakers weight. PMID:24204890

Recreating a functioning forest soil in reclaimed oil sands in northern alberta: an approach for measuring success in ecological restoration.

PubMed

Rowland, S M; Prescott, C E; Grayston, S J; Quideau, S A; Bradfield, G E

2009-01-01

During oil-sands mining all vegetation, soil, overburden, and oil sand is removed, leaving pits several kilometers wide and up to 100 m deep. These pits are reclaimed through a variety of treatments using subsoil or a mixed peat-mineral soil cap. Using nonmetric multidimensional scaling and cluster analysis of measurements of ecosystem function, reclamation treatments of several age classes were compared with a range of natural forest ecotypes to discover which treatments had created ecosystems similar to natural forest ecotypes and at what age this occurred. Ecosystem function was estimated from bioavailable nutrients, plant community composition, litter decomposition rate, and development of a surface organic layer. On the reclamation treatments, availability of nitrate, calcium, magnesium, and sulfur were generally higher than in the natural forest ecotypes, while ammonium, P, K, and Mn were generally lower. Reclamation treatments tended to have more bare ground, grasses, and forbs but less moss, lichen, shrubs, trees, or woody debris than natural forests. Rates of litter decomposition were lower on all reclamation treatments. Development of an organic layer appeared to be facilitated by the presence of shrubs. With repeated applications of fertilizers, measured variables for the peat-mineral amendments fell within the range of natural variability at about 20 yr. An intermediate subsoil layer reduced the need for fertilizer and conditions resembling natural forests were reached about 15 yr after a single fertilizer application. Treatments over tailings sand receiving only one application of fertilizer appeared to be on a different trajectory to a novel ecosystem.

Sub-soil microbial activity under rotational cotton crops in Australia

NASA Astrophysics Data System (ADS)

Polain, Katherine; Knox, Oliver; Wilson, Brian; Pereg, Lily

2016-04-01

Soil microbial communities contribute significantly to soil organic matter formation, stabilisation and destabilisation, through nutrient cycling and biodegradation. The majority of soil microbial research examines the processes occurring in the top 0 cm to 30 cm of the soil, where organic nutrients are easily accessible. In soils such as Vertosols, the high clay content causes swelling and cracking. When soil cracking is coupled with rain or an irrigation event, a flush of organic nutrients can move down the soil profile, becoming available for subsoil microbial community use and potentially making a significant contribution to nutrient cycling and biodegradation in soils. At present, the mechanisms and rates of soil nutrient turnover (such as carbon and nitrogen) at depth under cotton rotations are mostly speculative and the process-response relationships remain unclear, although they are undoubtedly underpinned by microbial activity. Our research aims to determine the contribution and role of soil microbiota to the accumulation, cycling and mineralisation of carbon and nitrogen through the whole root profile under continuous cotton (Gossypium hirsutum) and cotton-maize rotations in regional New South Wales, Australia. Through seasonal work, we have established both baseline and potential microbial activity rates from 0 cm to 100 cm down the Vertosol profile, using respiration and colourimetric methods. Further whole soil profile analyses will include determination of microbial biomass and isotopic carbon signatures using phospholipid fatty acid (PLFA) methodology, identification of microbial communities (sequencing) and novel experiments to investigate potential rates of nitrogen mineralisation and quantification of associated genes. Our preliminary observations and the hypotheses tested in this three-year study will be presented.

Slumping in the rain - winter soil structure across Scotland and its physical degradation from extreme weather

NASA Astrophysics Data System (ADS)

Hall, Rebecca; Hallett, Paul; Raffan, Annette; Lilly, Allan; Baggaley, Nikki; Rowan, John; Crookes, Bill; Ball, Bruce

2017-04-01

Scotland is blessed with fertile and resilient soils that produce great cereal yields and whisky. However, there is worrying anecdotal evidence, confirmed by a small body of science, that some farming practices are causing widespread physical degradation of these soils. Studies from other UK regions have identified soil physical degradation by compaction, unstable seedbeds and erosion as a moderate to serious problem, depending on farming practice, soil properties and climate. In 2015/2016 we sampled 120 fields from 4 catchments in Scotland to describe the state of soil structure in the winter. To obtain a rapid assessment, we used the increasingly popular and easily interpretable Visual Evaluations of Soil Structure (VESS) and Subsoil Structure (SubVESS). We found severe soil structural degradation in 18% of topsoils and 9% of subsoils for 120 fields in 4 catchments. The severe 2015/2016 winter precipitation, the worst ever recorded, caused a 30% increase in occurrence of severely degraded topsoils, as determined from sampling some of the same fields before and after this unprecedented weather event. Run-off, erosion and nutrient losses were about 10X from degraded parts of fields such as tramlines than either within the field or at less trafficked boundaries. There was some agreement between areas identified as structurally degraded and those ranked as being susceptible to topsoil compaction using a simple model. Broad scale surveys that incorporate temporal sampling, such as the study reported here, are essential to provide regional assessments of soil degradation and to inform follow-on, targeted studies, where more in-depth analysis would be feasible.

Small scale characterization of vine plant root zone via 3D electrical resistivity tomography and Mise-à-la-Masse method: a case study in a Bordeaux Vineyard

NASA Astrophysics Data System (ADS)

Mary, Benjamin; Peruzzo, Luca; Boaga, Jacopo; Schmutz, Myriam; Wu, Yuxin; Hubbard, Susan S.; Cassiani, Giorgio

2017-04-01

Nowadays, best viticulture practices require the joint interpretation of climate and soils data. However, information about the soil structure and subsoil processes is often lacking, as point measurements, albeit precise, cannot ensure sufficient spatial coverage and resolution. Non-invasive methods can provide spatially extensive, high resolution information that, supported by traditional point-like data, help complete the complex picture of subsoil static and dynamic reality. So far very little emphasis has been given to investigating the role of soil properties and even less of roots activity on winegrapes. Vine plant's root systems play an important role in providing the minerals to the plants, but also control the water uptake and thus the water state of the vines, which is a key factor determining the grape quality potential. In this contribution we report about the measurements conducted since June 2016 in a vineyard near Bordeaux (France, Pessac Leognan Chateau). Two neighbor plants of different sizes have been selected. In order to spot small scale soil variations and root zone physical structure at the vicinity of the vine plants, we applied a methodology using longitudinal 2D tomography, 3D borehole-based electrical resistivity tomography and a variation of the mise-à-la-masse method (MALM) to assess the effect of plant roots on the current injection in the ground. Time-lapse measurements are particularly informative about the plant dynamics, and the focus is particularly applied on this approach. The time-lapse 3D ERT and MALM results are presented, and the potential to assimilate these data into a hydrological model that can account for the root water uptake as a function of atmospheric conditions is discussed.

Autoclave treatment of pig manure does not reduce the risk of transmission and transfer of tetracycline resistance genes in soil: successive determinations with soil column experiments.

PubMed

Kang, Yijun; Gu, Xian; Hao, Yangyang; Hu, Jian

2016-03-01

The increasing use of antibiotics, especially tetracycline, in livestock feed adversely affects animal health and ecological integrity. Therefore, approaches to decrease this risk are urgently needed. High temperatures facilitate antibiotic degradation; whether this reduces transmission risk and transfer of tetracycline-resistant bacteria (TRBs) and tetracycline resistance genes (TRGs) in soil remains unknown. Successive experiments with soil columns evaluated the effects of autoclaving pig manure (APM) on soil TRB populations and TRGs over time at different soil depths. The data showed sharp increases in TRB populations and TRGs in each subsoil layer of PM (non-APM) and APM treatments within 30 days, indicating that TRBs and TRGs transferred rapidly. The level of TRBs in the upper soil layers was approximately 15-fold higher than in subsoils. TRBs were not dependent on PM and APM levels, especially in the late phase. Nevertheless, higher levels of APM led to rapid expansion of TRBs as compared to PM. Moreover, temporal changes in TRB frequencies in total culturable bacteria (TCBs) were similar to TRBs, indicating that the impact of PM or APM on TRBs was more obvious than for TCBs. TRBs were hypothesized to depend on the numbers of TRGs and indigenous recipient bacteria. In the plough layer, five TRGs (tetB, tetG, tetM, tetW, and tetB/P) existed in each treatment within 150 days. Selective pressure of TC may not be a necessary condition for the transfer and persistence of TRGs in soil. High temperatures might reduce TRBs in PM, which had minimal impact on the transmission and transfer of TRGs in soil. Identifying alternatives to decrease TRG transmission remains a major challenge.

Environmental remediation following the Fukushima-Daiichi accident

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tagawa, A.; Miyahara, K.; Nakayama, S.

2013-07-01

A wide area of Fukushima Prefecture was contaminated with radioactivity released by the Fukushima Daiichi nuclear accident. The decontamination pilot projects conducted by JAEA aimed at demonstrating the applicability of different techniques to rehabilitate affected areas. As most radioactive cesium is concentrated at the top of the soil column and strongly bound to mineral surfaces, there are 3 options left to decrease the gamma dose rate (usually measured 1 m above the ground surface): the stripping of the contaminated topsoil (i.e. direct removal of cesium), the dilution by mixing and the soil profile inversion. The last two options do notmore » generate waste. As the half-distance of {sup 137}Cs gammas in soil is in the order of 5-6 cm (depending on density and water content), the shielding by 50 cm of uncontaminated deep soil would theoretically reduce gamma doses by about 3 orders of magnitude. Which option is employed depends basically on the Cesium concentration in the topsoil, averaged over a 15-cm thickness. The JAEA's decontamination pilot projects focus on soil profile inversion and topsoil stripping. Two different techniques have been tested for the soil profile inversion: one is the reversal tillage by which surface soil of thickness of several tens of cm is reversed by using a tractor plough and the other is the complete interchanging of contaminated topsoil with uncontaminated subsoil by using a back-hoe. Reversal tillage with a tractor plough cost about 30 yen/m{sup 2}, which is an order of magnitude lower than that of topsoil-subsoil interchange (about 300 yen/m{sup 2}). Topsoil stripping is significantly more costly (between 550 yen/m{sup 2} and 690 yen/m{sup 2} according to the equipment used)« less

Vadose Zone Flow and Transport of Dissolved Organic Carbon at Multiple Scales in Humid Regimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jardine, Philip M; Mayes, Melanie; Mulholland, Patrick J

2006-06-01

Scientists must embrace the necessity to offset global CO{sub 2} emissions regardless of politics. Efforts to enhance terrestrial organic carbon sequestration have traditionally focused on aboveground biomass and surface soils. An unexplored potential exists in thick lower horizons of widespread, mature soils such as Alfisols, Ultisols, and Oxisols. We present a case study of fate and transport of dissolved organic carbon (DOC) in a highly weathered Ultisol, involving spatial scales from the laboratory to the landscape. Our objectives were to interpret processes observed at various scales and provide an improved understanding of coupled hydrogeochemical mechanisms that control DOC mobility andmore » sequestration in deep subsoils within humid climatic regimes. Our approach is multiscale, using laboratory-scale batch and soil columns (0.2 by 1.0 m), an in situ pedon (2 by 2 by 3 m), a well-instrumented subsurface facility on a subwatershed (0.47 ha), and ephemeral and perennial stream discharge at the landscape scale (38.4 ha). Laboratory-scale experiments confirmed that lower horizons have the propensity to accumulate DOC, but that preferential fracture flow tends to limit sequestration. Intermediate-scale experiments demonstrated the beneficial effects of C diffusion into soil micropores. Field- and landscape-scale studies demonstrated coupled hydrological, geochemical, and microbiological mechanisms that limit DOC sequestration, and their sensitivity to local environmental conditions. Our results suggest a multi-scale approach is necessary to assess the propensity of deep subsoils to sequester organic C in situ. By unraveling fundamental organic C sequestration mechanisms, we improve the conceptual and quantitative understanding needed to predict and alter organic C budgets in soil systems.« less

Soil fertility and plant diversity enhance microbial performance in metal-polluted soils.

PubMed

Stefanowicz, Anna M; Kapusta, Paweł; Szarek-Łukaszewska, Grażyna; Grodzińska, Krystyna; Niklińska, Maria; Vogt, Rolf D

2012-11-15

This study examined the effects of soil physicochemical properties (including heavy metal pollution) and vegetation parameters on soil basal respiration, microbial biomass, and the activity and functional richness of culturable soil bacteria and fungi. In a zinc and lead mining area (S Poland), 49 sites were selected to represent all common plant communities and comprise the area's diverse soil types. Numerous variables describing habitat properties were reduced by PCA to 7 independent factors, mainly representing subsoil type (metal-rich mining waste vs. sand), soil fertility (exchangeable Ca, Mg and K, total C and N, organic C), plant species richness, phosphorus content, water-soluble heavy metals (Zn, Cd and Pb), clay content and plant functional diversity (based on graminoids, legumes and non-leguminous forbs). Multiple regression analysis including these factors explained much of the variation in most microbial parameters; in the case of microbial respiration and biomass, it was 86% and 71%, respectively. The activity of soil microbes was positively affected mainly by soil fertility and, apparently, by the presence of mining waste in the subsoil. The mining waste contained vast amounts of trace metals (total Zn, Cd and Pb), but it promoted microbial performance due to its inherently high content of macronutrients (total Ca, Mg, K and C). Plant species richness had a relatively strong positive effect on all microbial parameters, except for the fungal component. In contrast, plant functional diversity was practically negligible in its effect on microbes. Other explanatory variables had only a minor positive effect (clay content) or no significant influence (phosphorus content) on microbial communities. The main conclusion from this study is that high nutrient availability and plant species richness positively affected the soil microbes and that this apparently counteracted the toxic effects of metal contamination. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of red mud on soil microbial communities: Application and comprehensive evaluation of the Biolog EcoPlate approach as a tool in soil microbiological studies.

PubMed

Feigl, Viktória; Ujaczki, Éva; Vaszita, Emese; Molnár, Mónika

2017-10-01

Red mud can be applied as soil ameliorant to acidic, sandy and micronutrient deficient soils. There are still knowledge gaps regarding the effects of red mud on the soil microbial community. The Biolog EcoPlate technique is a promising tool for community level physiological profiling. This study presents a detailed evaluation of Biolog EcoPlate data from two case studies. In experiment "A" red mud from Ajka (Hungary) was mixed into acidic sandy soil in soil microcosms at 5-50 w/w%. In experiement "B" red mud soil mixture was mixed into low quality subsoil in a field experiment at 5-50 w/w%. According to average well color development, substrate average well color development and substrate richness 5-20% red mud increased the microbial activity of the acidic sandy soil over the short term, but the effect did not last for 10months. Shannon diversity index showed that red mud at up to 20% did not change microbial diversity over the short term, but the diversity decreased by the 10th month. 30-50% red mud had deteriorating effect on the soil microflora. 5-20% red mud soil mixture in the low quality subsoil had a long lasting enhancing effect on the microbial community based on all Biolog EcoPlate parameters. However, 50% red mud soil mixture caused a decrease in diversity and substrate richness. With the Biolog EcoPlate we were able to monitor the changes of the microbial community in red mud affected soils and to assess the amount of red mud and red mud soil mixture applicable for soil treatment in these cases. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Soil Organic Matter Properties and Microbial Community Composition on Enzyme Activities in Cryoturbated Arctic Soils

PubMed Central

Schnecker, Jörg; Wild, Birgit; Hofhansl, Florian; Eloy Alves, Ricardo J.; Bárta, Jiří; Čapek, Petr; Fuchslueger, Lucia; Gentsch, Norman; Gittel, Antje; Guggenberger, Georg; Hofer, Angelika; Kienzl, Sandra; Knoltsch, Anna; Lashchinskiy, Nikolay; Mikutta, Robert; Šantrůčková, Hana; Shibistova, Olga; Takriti, Mounir; Urich, Tim; Weltin, Georg; Richter, Andreas

2014-01-01

Enzyme-mediated decomposition of soil organic matter (SOM) is controlled, amongst other factors, by organic matter properties and by the microbial decomposer community present. Since microbial community composition and SOM properties are often interrelated and both change with soil depth, the drivers of enzymatic decomposition are hard to dissect. We investigated soils from three regions in the Siberian Arctic, where carbon rich topsoil material has been incorporated into the subsoil (cryoturbation). We took advantage of this subduction to test if SOM properties shape microbial community composition, and to identify controls of both on enzyme activities. We found that microbial community composition (estimated by phospholipid fatty acid analysis), was similar in cryoturbated material and in surrounding subsoil, although carbon and nitrogen contents were similar in cryoturbated material and topsoils. This suggests that the microbial community in cryoturbated material was not well adapted to SOM properties. We also measured three potential enzyme activities (cellobiohydrolase, leucine-amino-peptidase and phenoloxidase) and used structural equation models (SEMs) to identify direct and indirect drivers of the three enzyme activities. The models included microbial community composition, carbon and nitrogen contents, clay content, water content, and pH. Models for regular horizons, excluding cryoturbated material, showed that all enzyme activities were mainly controlled by carbon or nitrogen. Microbial community composition had no effect. In contrast, models for cryoturbated material showed that enzyme activities were also related to microbial community composition. The additional control of microbial community composition could have restrained enzyme activities and furthermore decomposition in general. The functional decoupling of SOM properties and microbial community composition might thus be one of the reasons for low decomposition rates and the persistence of 400 Gt carbon stored in cryoturbated material. PMID:24705618

Colonization and community structure of arbuscular mycorrhizal fungi in maize roots at different depths in the soil profile respond differently to phosphorus inputs on a long-term experimental site.

PubMed

Wang, Chao; White, Philip J; Li, Chunjian

2017-05-01

Effects of soil depth and plant growth stages on arbuscular mycorrhizal fungal (AMF) colonization and community structure in maize roots and their potential contribution to host plant phosphorus (P) nutrition under different P-fertilizer inputs were studied. Research was conducted on a long-term field experiment over 3 years. AMF colonization was assessed by AM colonization rate and arbuscule abundances and their potential contribution to host P nutrition by intensity of fungal alkaline phosphatase (ALP)/acid phosphatase (ACP) activities and expressions of ZmPht1;6 and ZmCCD8a in roots from the topsoil and subsoil layer at different growth stages. AMF community structure was determined by specific amplification of 18S rDNA. Increasing P inputs up to 75-100 kg ha -1  yr -1 increased shoot biomass and P content but decreased AMF colonization and interactions between AMF and roots. AM colonization rate, intensity of fungal ACP/ALP activities, and expression of ZmPht1;6 in roots from the subsoil were greater than those from topsoil at elongation and silking but not at the dough stage when plants received adequate or excessive P inputs. Neither P input nor soil depth influenced the number of AMF operational taxonomic units (OTUs) present in roots, but P-fertilizer input, in particular, influenced community composition and relative AMF abundance. In conclusion, although increasing P inputs reduce AMF colonization and influence AMF community structure, AMF can potentially contribute to plant P nutrition even in well-fertilized soils, depending on the soil layer in which roots are located and the growth stage of host plants.

Carbon stock and turnover in riparian soils under lowland rainforest transformation systems on Sumatra, Indonesia

NASA Astrophysics Data System (ADS)

Hennings, Nina; Kuzyakov, Yakov

2017-04-01

In many tropical areas, rainforests are being cleared in order to exploit timber and other forest products as well as plant crops for food, feed and fuel use. The determinants of different patterns of deforestation and the roles of resulting transformation systems of tropical riparian rainforests for ecological functions have yet received little attention in scientific research. Especially C stocks in riparian zones are strongly affected by climate and land use changes that lead to changes in water regime and ground water level drops. We investigated the effects of land transformations in riparian ecosystems of Sumatra, on soil C content, stocks and decomposability at the landscape scale. We compare C losses in transformation systems and rainforests and estimate the contribution of soil erosion and organic matter mineralization. Further, these losses are related to changing water level and temperature increase along increasing distance to the stream. This approach is based on changing δ13C values of SOC in the topsoil as compared to those in subsoil. The shift of δ13C of SOC in the topsoil from the linear regression calculated by δ13C value with log(SOC) in the topsoil represents the modification of the C turnover rate in the top soil. Erosion is estimated by the shift of the δ13C value of SOC in the subsoil under plantations. Further, the δ13C and δ15N soil profiles and their comparison with litter of local vegetation, can be used to estimate the contribution of autochthonous and allochthonous organics to soil C stocks. Preliminary results show strong increase of erosive losses, increased decomposition with land-use transformation and decrease of C stocks with decreasing water table.

Root trait diversity, molecular marker diversity, and trait-marker associations in a core collection of Lupinus angustifolius.

PubMed

Chen, Yinglong; Shan, Fucheng; Nelson, Matthew N; Siddique, Kadambot Hm; Rengel, Zed

2016-06-01

Narrow-leafed lupin (Lupinus angustifolius L.) is the predominant grain legume crop in southern Australia, contributing half of the total grain legume production of Australia. Its yield in Australia is hampered by a range of subsoil constraints. The adaptation of lupin genotypes to subsoil constraints may be improved by selecting for optimal root traits from new and exotic germplasm sources. We assessed root trait diversity and genetic diversity of a core collection of narrow-leafed lupin (111 accessions) using 191 Diversity Arrays Technology (DArT) markers. The genetic relationship among accessions was determined using the admixture model in STRUCTURE. Thirty-eight root-associated traits were characterized, with 21 having coefficient of variation values >0.5. Principal coordinate analysis and cluster analysis of the DArT markers revealed broad diversity among the accessions. An ad hoc statistics calculation resulted in 10 distinct populations with significant differences among and within them (P < 0.001). The mixed linear model test in TASSEL showed a significant association between all root traits and some DArT markers, with the numbers of markers associated with an individual trait ranging from 2 to 13. The percentage of phenotypic variation explained by any one marker ranged from 6.4 to 21.8%, with 15 associations explaining >10% of phenotypic variation. The genetic variation values ranged from 0 to 7994, with 23 associations having values >240. Root traits such as deeper roots and lateral root proliferation at depth would be useful for this species for improved adaptation to drier soil conditions. This study offers opportunities for discovering useful root traits that can be used to increase the yield of Australian cultivars across variable environmental conditions. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Root trait diversity, molecular marker diversity, and trait-marker associations in a core collection of Lupinus angustifolius

PubMed Central

Chen, Yinglong; Shan, Fucheng; Nelson, Matthew N; Siddique, Kadambot HM; Rengel, Zed

2016-01-01

Narrow-leafed lupin (Lupinus angustifolius L.) is the predominant grain legume crop in southern Australia, contributing half of the total grain legume production of Australia. Its yield in Australia is hampered by a range of subsoil constraints. The adaptation of lupin genotypes to subsoil constraints may be improved by selecting for optimal root traits from new and exotic germplasm sources. We assessed root trait diversity and genetic diversity of a core collection of narrow-leafed lupin (111 accessions) using 191 Diversity Arrays Technology (DArT) markers. The genetic relationship among accessions was determined using the admixture model in STRUCTURE. Thirty-eight root-associated traits were characterized, with 21 having coefficient of variation values >0.5. Principal coordinate analysis and cluster analysis of the DArT markers revealed broad diversity among the accessions. An ad hoc statistics calculation resulted in 10 distinct populations with significant differences among and within them (P < 0.001). The mixed linear model test in TASSEL showed a significant association between all root traits and some DArT markers, with the numbers of markers associated with an individual trait ranging from 2 to 13. The percentage of phenotypic variation explained by any one marker ranged from 6.4 to 21.8%, with 15 associations explaining >10% of phenotypic variation. The genetic variation values ranged from 0 to 7994, with 23 associations having values >240. Root traits such as deeper roots and lateral root proliferation at depth would be useful for this species for improved adaptation to drier soil conditions. This study offers opportunities for discovering useful root traits that can be used to increase the yield of Australian cultivars across variable environmental conditions. PMID:27049020

Evaluation of subsoil competence for foundation studies at site III of the Delta State University, Nigeria

NASA Astrophysics Data System (ADS)

Ofomola, M. O.; Iserhien-Emekeme, R. E.; Okocha, F. O.; Adeoye, T. O.

2018-06-01

An integrated geophysical and geotechnical investigation has been carried out at site III of the Delta State University, Abraka, Nigeria. This took place in a bid to generate information on the competence of the soil in withstanding stress and strain emanating from overburden or pore pressure, swelling, cracking and other anthropogenic activity in relation to civil engineering and building structures. An electromagnetic method employing the very low frequency (VLF) technique, and electrical resistivity employing the Wenner and the vertical electrical sounding techniques were used for this study. Soil samples were also collected at depth for geotechnical analysis. Isoresistivity slices generated from the data of 33 VES stations at 1 m showed generally low resistivity values of subsurface earth materials, classified as clayey sand, sandy clay or clay, and ranging from 60-300 Ωm. However, at depths of 3 and 5 m, the result showed a generally high resistivity distribution with values ranging from 500-6000 Ωm, which is an indication of competent Earth materials of fine to coarse grain sand. The results of the liquid limit, plastic limit, plasticity index, cohesion, angle of internal friction and clay content of the soil samples vary from 10%-17%, 18%-29%, 3%-15%, 45-95 KN m-2, 31°-35° and 14%-22% respectively. The low cohesion, low clay content and high angle of internal friction of the soil at the encountered depth makes it competent for engineering foundation. It is concluded that the subsoil in the area, starting at a depth of 3 m, is a competent material for hosting engineering structures.

Use of stable isotopes of carbon, nitrogen, and sulfer to identify sources of nitrogen in surface waters in the Lower Susquehanna River basin, Pennsylvania

USGS Publications Warehouse

Cravotta, C.A.

1995-01-01

Stable isotopes of carbon (C), nitrogen (N), and sulfur (S) in nitrogen sources and nearby samples of topsoil, subsoil, runoff water, and stream water were measured to evaluate the feasibility of using isotopic data to identify nitrogen sources in stream water from forested, agricultural, or suburban land-use areas. Chemical and isotopic compositions were measured for six N-source types consisting of rain water, forest-leaf litter, synthetic fertilizer, farm-animal manure, municipal-sewage effluent and sludge, and septic-tank effluent and sludge. Compositions of topsoil, subsoil, runoff water, and stream water were measured to evaluate changes in compositions of transported N-containing materials near the N source. Animal manure, human waste (sewage plus septic), and forest-leaf litter can be distinguished on the basis of C; however, most N-sources can not be distinguished on the basis of N and S, owing to wide ranges of compositions and overlap among different N-source types. Although values of N for soil and runoff-water samples are qualitatively similar to those of the applied N source, values of C and S for runoff-water and stream-water samples appear to reflect the compositions of relatively large reservoirs of the elements in soil organic matter and minerals, respectively, and not the composition of the applied N source. Because of incomplete chemical transfor- mations, the ratio of organic carbon to total nitrogen for particulates in runoff or stream waters generally is lower than that for associated, nearby soils, and isotopic compositions commonly differ between particulate and dissolved fractions in the water.

A microtremor survey to define the subsoil structure in a mud volcano areas

NASA Astrophysics Data System (ADS)

Panzera, Francesco; D'Amico, Sebastiano; Lupi, Matteo; Karyono, Karyono; Mazzini, Adriano

2017-04-01

Mud erupting systems have been observed and studied in different localities on the planet. They are characterized by emissions of fluids and fragmented sedimentary rocks creating large structures with different morphologies. This is mainly due to the presence of clay-bearing strata that can be buoyant in the surrounding regions and over-pressured fluids that facilitate the formation of diapirs through sedimentary rocks. In this study, we investigate the Lusi mud erupting system mainly by using ambient vibration methods. In particular, thickness of the sediments and the body wave velocities have been investigated. Results are integrated with gravimetry and electrical resistivity data in order to locate the main geological discontinuities in the area as well as to reconstruct a 3D model of the buried structure. The approach commonly used for this type of studies is based on the ratio of the horizontal to vertical components of ground motion (HVSR) and on passive array techniques. The HVSR generally enables to recognize peaks that point out to the fundamental frequency of the site, which usually fit quite well the theoretical resonance curves. The combination of HVSR and shear wave velocity, coming from passive array techniques, enables to collect valuable information about the subsurface structures. Here we present new data collected at the mud volcano and sedimentary hosted hydrothermal system sites in order to investigate the depths of the main discontinuities and of the hypothesized hydrocarbon reservoirs. We present the case study of Salse di Nirano (northen Italy), Salinelle (Mt. Etna, Sicily) and Lusi hydrothermal systems (Indonesia). Our results indicate that the ambient vibrations study approach represents a swift and simplified methods that provides quick information on the shallow subsoil structure of the investigated areas.

Load dissipation by corn residue on tilled soil in laboratory and field-wheeling conditions.

PubMed

Reichert, José M; Brandt, André A; Rodrigues, Miriam F; Reinert, Dalvan J; Braida, João A

2016-06-01

Crop residues may partially dissipate applied loads and reduce soil compaction. We evaluated the effect of corn residue on energy-applied dissipation during wheeling. The experiment consisted of a preliminary laboratory test and a confirmatory field test on a Paleaudalf soil. In the laboratory, an adapted Proctor test was performed with three energy levels, with and without corn residue. Field treatments consisted of three 5.1 Mg tractor wheeling intensities (0, 2, and 6), with and without 12 Mg ha(-1) corn residue on the soil surface. Corn residue on the soil surface reduced soil bulk density in the adapted Proctor test. By applying energy of 52.6 kN m m(-3) , soil dissipated 2.98% of applied energy, whereas with 175.4 kN m m(-3) a dissipation of 8.60% was obtained. This result confirms the hypothesis that surface mulch absorbs part of the compaction effort. Residue effects on soil compaction observed in the adapted Proctor test was not replicated under subsoiled soil field conditions, because of differences in applied pressure and soil conditions (structure, moisture and volume confinement). Nevertheless, this negative result does not mean that straw has no effect in the field. Such effects should be measured via stress transmission and compared to soil load-bearing capacity, rather than on bulk deformations. Wheeling by heavy tractor on subsoiled soil increased compaction, independently of surface residue. Two wheelings produced a significantly increase, but six wheelings did not further increase compaction. Reduced traffic intensity on recently tilled soil is necessary to minimize soil compaction, since traffic intensity show a greater effect than surface mulch on soil protection from excessive compaction. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Geotechnical Parameters of Alluvial Soils from in-situ Tests

NASA Astrophysics Data System (ADS)

Młynarek, Zbigniew; Stefaniak, Katarzyna; Wierzbicki, Jędrzej

2012-10-01

The article concentrates on the identification of geotechnical parameters of alluvial soil represented by silts found near Poznan and Elblag. Strength and deformation parameters of the subsoil tested were identified by the CPTU (static penetration) and SDMT (dilatometric) methods, as well as by the vane test (VT). Geotechnical parameters of the subsoil were analysed with a view to using the soil as an earth construction material and as a foundation for buildings constructed on the grounds tested. The article includes an analysis of the overconsolidation process of the soil tested and a formula for the identification of the overconsolidation ratio OCR. Equation 9 reflects the relation between the undrained shear strength and plasticity of the silts analyzed and the OCR value. The analysis resulted in the determination of the Nkt coefficient, which might be used to identify the undrained shear strength of both sediments tested. On the basis of a detailed analysis of changes in terms of the constrained oedometric modulus M0, the relations between the said modulus, the liquidity index and the OCR value were identified. Mayne's formula (1995) was used to determine the M0 modulus from the CPTU test. The usefullness of the sediments found near Poznan as an earth construction material was analysed after their structure had been destroyed and compacted with a Proctor apparatus. In cases of samples characterised by different water content and soil particle density, the analysis of changes in terms of cohesion and the internal friction angle proved that these parameters are influenced by the soil phase composition (Fig. 18 and 19). On the basis of the tests, it was concluded that the most desirable shear strength parameters are achieved when the silt is compacted below the optimum water content.

Geotechnical Parameters of Alluvial Soils from in-situ Tests

NASA Astrophysics Data System (ADS)

Młynarek, Zbigniew; Stefaniak, Katarzyna; Wierzbicki, Jedrzej

2012-10-01

The article concentrates on the identification of geotechnical parameters of alluvial soil represented by silts found near Poznan and Elblag. Strength and deformation parameters of the subsoil tested were identified by the CPTU (static penetration) and SDMT (dilatometric) methods, as well as by the vane test (VT). Geotechnical parameters of the subsoil were analysed with a view to using the soil as an earth construction material and as a foundation for buildings constructed on the grounds tested. The article includes an analysis of the overconsolidation process of the soil tested and a formula for the identification of the overconsolidation ratio OCR. Equation 9 reflects the relation between the undrained shear strength and plasticity of the silts analyzed and the OCR value. The analysis resulted in the determination of the Nkt coefficient, which might be used to identify the undrained shear strength of both sediments tested. On the basis of a detailed analysis of changes in terms of the constrained oedometric modulus M0, the relations between the said modulus, the liquidity index and the OCR value were identified. Mayne's formula (1995) was used to determine the M0 modulus from the CPTU test. The usefullness of the sediments found near Poznan as an earth construction material was analysed after their structure had been destroyed and compacted with a Proctor apparatus. In cases of samples characterised by different water content and soil particle density, the analysis of changes in terms of cohesion and the internal friction angle proved that these parameters are influenced by the soil phase composition (Fig. 18 and 19). On the basis of the tests, it was concluded that the most desirable shear strength parameters are achieved when the silt is compacted below the optimum water content.

Root carbon decomposition and microbial biomass response at different soil depths

NASA Astrophysics Data System (ADS)

Rumpel, C.

2012-12-01

The relationship between root litter addition and soil organic matter (SOM) formation in top- versus subsoils is unknown. The aim of this study was to investigate root litter decomposition and stabilisation in relation to microbial parameters in different soil depths. Our conceptual approach included incubation of 13C-labelled wheat roots at 30, 60 and 90 cm soil depth for 36 months under field conditions. Quantitative root carbon contribution to SOM was assessed, changes of bulk root chemistry studied by solid-state 13C NMR spectroscopy and lignin content and composition was assessed after CuO oxidation. Compound-specific isotope analysis allowed to assess the role of root lignin for soil C storage in the different soil depths. Microbial biomass and community structure was determined after DNA extraction. After three years of incubation, O-alkyl C most likely assigned to polysaccharides decreased in all soil depth compared to the initial root material. The degree of root litter decomposition assessed by the alkyl/O-alkyl ratio decreased with increasing soil depth, while aryl/O-alkyl ratio was highest at 60 cm depth. Root-derived lignin showed depth specific concentrations (30 < 90 < 60 cm). Its composition was soil depth independent suggesting that microbial communities in all three soil depths had similar degradation abilities. Microbial biomass C and fungi contribution increased after root litter addition. Their community structure changed after root litter addition and showed horizon specific dynamics. Our study shows that root litter addition can contribute to C storage in subsoils but did not influence C storage in topsoil. We conclude that specific conditions of single soil horizons have to be taken into account if root C dynamics are to be fully understood.

Microbial Community Dynamics in Soil Depth Profiles Over 120,000 Years of Ecosystem Development

PubMed Central

Turner, Stephanie; Mikutta, Robert; Meyer-Stüve, Sandra; Guggenberger, Georg; Schaarschmidt, Frank; Lazar, Cassandre S.; Dohrmann, Reiner; Schippers, Axel

2017-01-01

Along a long-term ecosystem development gradient, soil nutrient contents and mineralogical properties change, therefore probably altering soil microbial communities. However, knowledge about the dynamics of soil microbial communities during long-term ecosystem development including progressive and retrogressive stages is limited, especially in mineral soils. Therefore, microbial abundances (quantitative PCR) and community composition (pyrosequencing) as well as their controlling soil properties were investigated in soil depth profiles along the 120,000 years old Franz Josef chronosequence (New Zealand). Additionally, in a microcosm incubation experiment the effects of particular soil properties, i.e., soil age, soil organic matter fraction (mineral-associated vs. particulate), O2 status, and carbon and phosphorus additions, on microbial abundances (quantitative PCR) and community patterns (T-RFLP) were analyzed. The archaeal to bacterial abundance ratio not only increased with soil depth but also with soil age along the chronosequence, coinciding with mineralogical changes and increasing phosphorus limitation. Results of the incubation experiment indicated that archaeal abundances were less impacted by the tested soil parameters compared to Bacteria suggesting that Archaea may better cope with mineral-induced substrate restrictions in subsoils and older soils. Instead, archaeal communities showed a soil age-related compositional shift with the Bathyarchaeota, that were frequently detected in nutrient-poor, low-energy environments, being dominant at the oldest site. However, bacterial communities remained stable with ongoing soil development. In contrast to the abundances, the archaeal compositional shift was associated with the mineralogical gradient. Our study revealed, that archaeal and bacterial communities in whole soil profiles are differently affected by long-term soil development with archaeal communities probably being better adapted to subsoil conditions, especially in nutrient-depleted old soils. PMID:28579976

Biogeochemistry of the rare-earth elements with particular reference to hickory trees

USGS Publications Warehouse

Robinson, W.O.; Bastron, H.; Murata, K.J.

1958-01-01

Hickory trees concentrate the rare-earth elements in their leaves to a phenomenal degree and may contain as much as 2300 p.p.m. of total rare earths based on the dry weight of the leaves. The average proportions of the individual elements (atomic percent of the total rare-earth elements) in the leaves are: Y 36, La 16, Ce 14, Pr 2, Nd 20, Sm 1, Eu 0.7, Gd 3, Tb 0.6, Dy 3, Ho 0.7, Er 2, Tm 0.2, Yb 1, and Lu 0.2. The similarity in the proportions of the rare-earth elements in the leaves and in the exchange complex of the soil on which the hickory trees grow indicates that the trees do not fractionate the rare earths appreciably. The variation of the rare-earth elements in the leaves and soils can be explained generally in terms of the relative abundance of the cerium group and the yttrium group, except for the element cerium. The large fluctuations in the proportion of cerium [Ce/(La + Nd) atomic ratios of 0.16 to 0.86] correlate with oxidation-reduction conditions in the soil profile. The substitution of dilute H2SO3 for dilute HC1 in the determination of available rare-earth elements brings about a large increase in the proportion of cerium that is extracted from an oxygenated subsoil. These relationships strongly suggest that quadrivalent cerium is present in oxygenated subsoil and is less available to plants than the other rare-earth elements that do not undergo such a change in valence. A few parts per billion of rare-earth elements have been detected in two samples of ground water. ?? 1958.

Comparison of spatial association approaches for landscape mapping of soil organic carbon stocks

NASA Astrophysics Data System (ADS)

Miller, B. A.; Koszinski, S.; Wehrhan, M.; Sommer, M.

2015-03-01

The distribution of soil organic carbon (SOC) can be variable at small analysis scales, but consideration of its role in regional and global issues demands the mapping of large extents. There are many different strategies for mapping SOC, among which is to model the variables needed to calculate the SOC stock indirectly or to model the SOC stock directly. The purpose of this research is to compare direct and indirect approaches to mapping SOC stocks from rule-based, multiple linear regression models applied at the landscape scale via spatial association. The final products for both strategies are high-resolution maps of SOC stocks (kg m-2), covering an area of 122 km2, with accompanying maps of estimated error. For the direct modelling approach, the estimated error map was based on the internal error estimations from the model rules. For the indirect approach, the estimated error map was produced by spatially combining the error estimates of component models via standard error propagation equations. We compared these two strategies for mapping SOC stocks on the basis of the qualities of the resulting maps as well as the magnitude and distribution of the estimated error. The direct approach produced a map with less spatial variation than the map produced by the indirect approach. The increased spatial variation represented by the indirect approach improved R2 values for the topsoil and subsoil stocks. Although the indirect approach had a lower mean estimated error for the topsoil stock, the mean estimated error for the total SOC stock (topsoil + subsoil) was lower for the direct approach. For these reasons, we recommend the direct approach to modelling SOC stocks be considered a more conservative estimate of the SOC stocks' spatial distribution.

Comparison of spatial association approaches for landscape mapping of soil organic carbon stocks

NASA Astrophysics Data System (ADS)

Miller, B. A.; Koszinski, S.; Wehrhan, M.; Sommer, M.

2014-11-01

The distribution of soil organic carbon (SOC) can be variable at small analysis scales, but consideration of its role in regional and global issues demands the mapping of large extents. There are many different strategies for mapping SOC, among which are to model the variables needed to calculate the SOC stock indirectly or to model the SOC stock directly. The purpose of this research is to compare direct and indirect approaches to mapping SOC stocks from rule-based, multiple linear regression models applied at the landscape scale via spatial association. The final products for both strategies are high-resolution maps of SOC stocks (kg m-2), covering an area of 122 km2, with accompanying maps of estimated error. For the direct modelling approach, the estimated error map was based on the internal error estimations from the model rules. For the indirect approach, the estimated error map was produced by spatially combining the error estimates of component models via standard error propagation equations. We compared these two strategies for mapping SOC stocks on the basis of the qualities of the resulting maps as well as the magnitude and distribution of the estimated error. The direct approach produced a map with less spatial variation than the map produced by the indirect approach. The increased spatial variation represented by the indirect approach improved R2 values for the topsoil and subsoil stocks. Although the indirect approach had a lower mean estimated error for the topsoil stock, the mean estimated error for the total SOC stock (topsoil + subsoil) was lower for the direct approach. For these reasons, we recommend the direct approach to modelling SOC stocks be considered a more conservative estimate of the SOC stocks' spatial distribution.

Rehabilitation of a Distressed Single Storied Building Founded on Expansive Soil: A Case Study

NASA Astrophysics Data System (ADS)

Pakrashi, Somdev

2017-12-01

A single storied building was constructed on strip foundation system—on a subsoil, with high expansivity, without taking necessary precautions and it suffered extensive cracks and damages in roof slab, beams, columns and brick walls, subsidence /upheavals in floors etc. within 2/3 years of its construction and consequently it had to be abandoned. The study examines the reasons for the severe damages, cracks etc. and also suggests remediation by ground improvement and other necessary measures that were actually taken up, to rehabilitate the highly distressed and abandoned building within a reasonably short period of time—at a reasonable cost.

Microbial N and P mining regulates the effect of N deposition on soil organic matter turnover

NASA Astrophysics Data System (ADS)

Meyer, Nele; Welp, Gerhard; Rodionov, Andrei; Borchard, Nils; Martius, Christopher; Amelung, Wulf

2017-04-01

Nitrogen (N) deposition to soils has become a global issue during the last decades. Its effect on mineralization of soil organic carbon (SOC), however, is still debated. Common theories based on Liebig's law predict higher SOC mineralization rates in nutrient-rich than in nutrient-poor soils. Contrastingly, the concept of microbial N mining predicts lower mineralization rates after N deposition. The latter is explained by ceased decomposition of recalcitrant soil organic matter (SOM) as the need of microbes to acquire N from this pool decreases. As N deposition might shift the nutrient balance towards relative phosphorus (P) deficiency, it is also necessary to consider P mining in this context. Due to limited knowledge about microbial nutrient mining, any predictions of N deposition effects are difficult. This study aims at elucidating the preconditions under which microbial nutrient mining occurs in soil. We hypothesized that the occurrence of N and P mining is controlled by the current nutrient status of the soil. Likewise, soils might respond differently to N additions. To investigate this hypothesis, we conducted substrate-induced respiration measurements on soils with pronounced gradients of N and P availability. We used topsoil samples taken repeatedly from a site which was up to 7 years under bare fallow (Selhausen, Germany) and up to 4 m deep tropical forest soils (Kalimantan, Indonesia). Additional nutrient manipulations (glucose, glucose+N, glucose+P, glucose+N+P additions) were conducted to study the effect of nutrient additions. Samples were incubated for one month. We further conducted 13C labeling experiments to trace the sources of CO2 (sugar vs. SOM derived CO2) for further hints on nutrient mining. Mineralization of glucose was limited by a lack of available N in the bare fallow soil but microbes were able to slowly acquire N from previously unavailable pools. This resulted in a slightly higher release of native SOM-derived CO2 compared to N-fertilized treatments. Nutrient additions had no effect on cumulative CO2 evolution in tropical topsoils. Subsoils of the tropical sites (20 - 100 cm depth) were co-limited by N and P. Here, alleviation of either N or P deficiency was necessary to stimulate the mineralization of glucose. In the deep subsoil (>150 cm depth) only the combined additions of N+P induced any CO2 release. Our results reveal that mining of both N and P potentially occurs but is restricted by multiple nutrient limitations, by the absence of potentially accessible nutrients (e.g., in the deep subsoil), and by full nutrient supply (e.g., high nutrient contents make mining unnecessary). The results suggest several implications for N deposition effects: 1) N deposition decreases (recalcitrant) SOC mineralization in former N-deficient soils, 2) N deposition increases SOC mineralization in former co-limited soils as it facilitates mining of the required P, 3) N deposition has no effect in nutrient rich topsoils.

Woody plant encroachment effect on soil organic carbon dynamics: results from a latitudinal gradient in Italy

NASA Astrophysics Data System (ADS)

Pellis, Guido; Chiti, Tommaso; Moscatelli, Maria Cristina; Marinari, Sara; Papale, Dario

2016-04-01

Woody plant encroachment into pastures and grasslands represents a significant land cover change phenomenon, with a considerable impact on carbon dynamics at an ecosystem level. It was estimated that 7.64% of the Southern Europe land was subject to that process between 1950 to 2010. As a result of woody encroachment, changes in vegetation composition can produce substantial changes to the soil organic carbon (SOC) cycle. Despite the numerous papers published on land-use change, an evaluation of the IPCC terrestrial carbon pools changes occurring during woody encroachment on abandoned pastures and grasslands is still lacking, particularly for the Italian territory. Therefore, the aim of this study was to investigate the role of woody encroachment on carbon sequestration over abandoned pastures and grasslands in Alpine and Apennine ecosystems, with a particular focus on the SOC. We applied a chronosequence approach to seven selected sites located along a latitudinal gradient in Italy. Each chronosequence consisted of a pasture currently managed, three sites abandoned at different times in the past and, finally, a mature forest stand representing the last phase of the succession. The European Commission sampling protocols to certify SOC changes was adopted to estimate the variations following woody encroachment. Soil samples were collected at different depths in the topsoil (0-30 cm) and subsoil (30-70 cm), despite the original protocol formulation being limited to the topsoil only. In addition, aboveground living biomass (AGB), dead wood and litter were also measured following international protocols. Considering all C pools together, woody plant encroachment leads to a progressive C stock accumulation in all the chronosequences. The total C stock of mature forest stands ranges from 1.78±0.11 times (Eastern Alps) to 2.48±0.31 times (central Apennine) the initial value on pastures. Unsurprisingly, the C stocks of AGB, dead wood and litter all increase during the process of woody encroachment. Instead, the SOC dynamics are more complex, as previous studies suggest they are strongly affected by precipitation and temperature. Accordingly, we found that in the Apennine sites, characterised by a Mediterranean mountainous climate, the SOC increased more than 50% from pasture to forest stages. Conversely, the increment appears not or barely statistically significant in the two colder and more humid Eastern Alps sites. Our results also indicate a substantial amount of SOC is stored in the subsoil, despite many existing sampling protocols (including the original form of the one we adopted) typically restrict measurements only to the topsoil. Therefore, it is recommended to measure the SOC along the whole profile to avoid overlooking the significant amount of C that can accumulate in the subsoil during the process of woody encroachment. In conclusion, this study reveals a positive impact of woody encroachment in increasing the C at an ecosystem level and suggests that SOC measurements are extremely important when precise emission-removal estimates due to land use change are required.

Exposure assessment of a burning ground for chemical ammunition on the Great War battlefields of Verdun.

PubMed

Bausinger, Tobias; Bonnaire, Eric; Preuss, Johannes

2007-09-01

The destruction of arsenical shells from the 1914/18 war in the vicinity of Verdun (France) during the 1920s resulted in a locally limited but severe soil contamination by arsenic and heavy metals. At the study site, the main part of the contaminant inventory occurs in the upper 20 cm of the topsoil which is essentially composed of combustion residues. Besides, some Cu (cmax.=16,877 mg/kg) and Pb (cmax.=26,398 mg/kg) in this layer, As (cmax.=175,907 mg/kg) and Zn (cmax.=133,237 mg/kg) were detected in very high concentrations. The mobilities of Cu, Mn, Pb and Zn in the soil system were derived from ammonium nitrate eluates. They are strongly influenced by the soil pH and can be described by quadratic regression curves from which threshold pH values were calculated. Below these values more than 10% of the element content was available as mobile species. Within the examined pH range, this method could not be adopted for arsenic, because the mobility of As was only slightly controlled by the soil pH. In the heavily contaminated topsoil, Cu and Pb were fixed by the moderately acidic soil pH which varied from 4.8 to 5.8. No migration to the underlying horizons occurred. A different behavior was observed for As and Zn. The calculated threshold pH of Zn was 5.5, so certain amount of this element was transferred to the subsoil and the leachate (cmax.=350 microg/l). However, a major dispersion of Zn was prevented by a rise of the soil pH in the carbonate-containing subsoil. Elevated concentrations of As were found in all soil horizons up to a depth of 2 m and also in the leachate (cmax.=2377 microg/l). Contrary to Cu, Pb and Zn the mobility of As evidently was less affected by the subsoil. Regarding organic contaminants, nitroaromatic explosives were detected only in minor concentrations in the soil (cmax.=14.7 mg/kg) and the leachate (cmax.=13.5 microg/l). No aromatic organoarsenicals were detected in the soil and the leachate samples. The main hazard of the site is the severe arsenic contamination and the transfer of this carcinogen by leachate, surface runoff and probably by wind. Nevertheless, some studies on the effects of the contaminant inventory on the local vegetation revealed that ammonium nitrate elutable zinc is responsible for the spatial distribution of some tolerant plant species and not arsenic. Previously undetected buried munitions from the former delaboration facility can be an other source of environmental contaminants. This is supported by elevated concentrations of chlorate (cmax.=71 mg/l) and perchlorate (cmax.=0.8 mg/l) detected in the leachate samples. This is the second report about environmental contamination related to post-war ammunition destruction activities along the 1914/18 Western Front.

Effects of Management Practices on Meloidogyne incognita and Snap Bean Yield.

PubMed

Smittle, D A; Johnson, A W

1982-01-01

Phenamiphos applied at 6.7 kg ai/ha through a solid set or a center pivot irrigation system with 28 mm of water effectively controlled root-knot nematodes, Meloidogyne incognita, and resulted in greater snap bean growth and yields irrespective of growing season, tillage method, or cover crop system. The percentage yield increases attributed to this method of M. incognita control over nontreated controls were 45% in the spring crop, and 90% and 409% in the fall crops following winter rye and fallow, respectively. Root galling was not affected by tillage systems or cover crop, but disk tillage resulted in over 50% reduction in bean yield compared with yields from the subsoil-bed tillage system.

High lateral resolution exploration using surface waves from noise records

NASA Astrophysics Data System (ADS)

Chávez-García, Francisco José Yokoi, Toshiaki

2016-04-01

Determination of the shear-wave velocity structure at shallow depths is a constant necessity in engineering or environmental projects. Given the sensitivity of Rayleigh waves to shear-wave velocity, subsoil structure exploration using surface waves is frequently used. Methods such as the spectral analysis of surface waves (SASW) or multi-channel analysis of surface waves (MASW) determine phase velocity dispersion from surface waves generated by an active source recorded on a line of geophones. Using MASW, it is important that the receiver array be as long as possible to increase the precision at low frequencies. However, this implies that possible lateral variations are discarded. Hayashi and Suzuki (2004) proposed a different way of stacking shot gathers to increase lateral resolution. They combined strategies used in MASW with the common mid-point (CMP) summation currently used in reflection seismology. In their common mid-point with cross-correlation method (CMPCC), they cross-correlate traces sharing CMP locations before determining phase velocity dispersion. Another recent approach to subsoil structure exploration is based on seismic interferometry. It has been shown that cross-correlation of a diffuse field, such as seismic noise, allows the estimation of the Green's Function between two receivers. Thus, a virtual-source seismic section may be constructed from the cross-correlation of seismic noise records obtained in a line of receivers. In this paper, we use the seismic interferometry method to process seismic noise records obtained in seismic refraction lines of 24 geophones, and analyse the results using CMPCC to increase the lateral resolution of the results. Cross-correlation of the noise records allows reconstructing seismic sections with virtual sources at each receiver location. The Rayleigh wave component of the Green's Functions is obtained with a high signal-to-noise ratio. Using CMPCC analysis of the virtual-source seismic lines, we are able to identify lateral variations of phase velocity inside the seismic line, and increase the lateral resolution compared with results of conventional analysis.

Vegetation-induced spatial variability of soil redox properties in wetlands

NASA Astrophysics Data System (ADS)

Szalai, Zoltán; Jakab, Gergely; Kiss, Klaudia; Ringer, Marianna; Balázs, Réka; Zacháry, Dóra; Horváth Szabó, Kata; Perényi, Katalin

2016-04-01

Vegetation induced land patches may result spatial pattern of on soil Eh and pH. These spatial pattern are mainly emerged by differences of aeration and exudation of assimilates. Present paper focuses on vertical extent and temporal dynamics of these patterns in wetlands. Two study sites were selected: 1. a plain wetland on calcareous sandy parent material (Ceglédbercel, Danube-Tisza Interfluve, Hungary); 2. headwater wetland with calcareous loamy parent material (Bátaapáti, Hungary). Two vegetation patches were studied in site 1: sedgy (dominated by Carex riparia) and reedy (dominated by Phragmites australis). Three patches were studied in site2: sedgy1 (dominated by C vulpina), sedgy 2 (C. riparia); nettle-horsetail (Urtica dioica and Equisetum arvense). Boundaries between patches were studied separately. Soil redox, pH and temperature studied by automated remote controlled instruments. Three digital sensors (Ponsell) were installed in each locations: 20cm and 40cm sensors represent the solum and 100 cm sensor monitors the subsoil). Groundwater wells were installed near to triplets for soil water sampling. Soil Eh, pH and temperature values were recorded in each 10 minutes. Soil water sampling for iron and DOC were carried out during saturated periods. Spatial pattern of soil Eh is clearly caused by vegetation. We measured significant differences between Eh values of the studied patches in the solum. We did not find this kinds horizontal differences in the subsoil. Boundaries of the patches usually had more reductive soil environment than the core areas. We have found temporal dynamics of the spatial redox pattern. Differences were not so well expressed during wintertime. These spatial patterns had influence on the DOC and iron content of porewater, as well. Highest temporal dynamics of soil redox properties and porewater iron could be found in the boundaries. These observations refer to importance patchiness of vegetation on soil chemical properties in wetlands. Authors are grateful to Hungarian Scientific research Fund (K100180)

Redistribution of exchangeable calcium, magnesium, and aluminum following lime or gypsum applications to a Brazilian Oxisol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavan, M.A.; Bingham, F.T.; Pratt, P.F.

A greenhouse experiment was carried out with 16 columns of an undisturbed Oxisol that had sufficient subsoil acidity to restrict root growth of a wide variety of crop plants. The objective was to determine the effects of surface applied CaCO/sub 3/, CaSO/sub 4/ x 2H/sup 2/O, and water on subsoil pH and exchangeable Al, Ca, and Mg. Eight soil columns were treated with CaCO/sub 3/ or CaSO/sub 4/ x 2H/sup 2/O at rates equal to 0.25 and 1.50 x the lime equivalent (KCL-extractable Al). The irrigation treatments consisted of trickle irrigation applied at 8.94 and 17.88 mm day/sup -1/ formore » 6 months. These treatments were superimposed on the amendment treatments. Observations included volume and composition of drainage water during the course of the experiment and chemical composition of the soil column by depth increments once the irrigation treatments were completed. Soil analysis included pH, cation exchange capacity (CEC), exchangeable cations, and composition of saturation extracts of soil. Effects of CaCO/sub 3/ treatments were observed only in the upper 20 cm of the profiles irrespective of irrigation and fertilizer treatments. The CaCO/sub 3/ treatments increased soil pH, CEC, and exchangeable Al; and CaSO/sub 4/ x 2H/sup 2/O treatments reduced the level of exchangeable Al and Mg throughout the 100-cm depth profiles while increasing the level of exhangeable Ca. Soil pH and CEC were unaffected by the latter treatment. Based on the effectiveness of CaSO/sup 4/ x 2H/sup 2/O in reducing exchangeable Al and Mg while increasing exchangeable Ca, the combination of dolomitic lime and gypsum appears to be an appropriate amendment treatment for Oxisols with toxic concentrations of available Al.« less

Airborne dust transport to the eastern Pacific Ocean off southern California: Evidence from San Clemente Island

USGS Publications Warehouse

Muhs, D.R.; Budahn, J.; Reheis, M.; Beann, J.; Skipp, G.; Fisher, E.

2007-01-01

Islands are natural dust traps, and San Clemente Island, California, is a good example. Soils on marine terraces cut into Miocene andesite on this island are clay-rich Vertisols or Alfisols with vertic properties. These soils are overlain by silt-rich mantles, 5-20 cm thick, that contrast sharply with the underlying clay-rich subsoils. The silt mantles have a mineralogy that is distinct from the island bedrock. Silt mantles are rich in quartz, which is rare in the island andesite. The clay fraction of the silt mantles is dominated by mica, also absent from local andesite, and contrasts with the subsoils, dominated by smectite. Ternary plots of immobile trace elements (Sc-Th-La and Ta-Nd-Cr) show that the island andesite has a composition intermediate between average upper continental crust and average oceanic crust. In contrast, the silt and, to a lesser extent, clay fractions of the silt mantles have compositions closer to average upper continental crust. The silt mantles have particle size distributions similar to loess and Mojave Desert dust, but are coarser than long-range-transported Asian dust. We infer from these observations that the silt mantles are derived from airborne dust from the North American mainland, probably river valleys in the coastal mountains of southern California and/or the Mojave Desert. Although average winds are from the northwest in coastal California, easterly winds occur numerous times of the year when "Santa Ana" conditions prevail, caused by a high-pressure cell centered over the Great Basin. Examination of satellite imagery shows that easterly Santa Ana winds carry abundant dust to the eastern Pacific Ocean and the California Channel Islands. Airborne dust from mainland North America may be an important component of the offshore sediment budget in the easternmost Pacific Ocean, a finding of potential biogeochemical and climatic significance.

Microbial nitrogen dynamics in organic and mineral soil horizons along a latitudinal transect in western Siberia

PubMed Central

Wild, Birgit; Schnecker, Jörg; Knoltsch, Anna; Takriti, Mounir; Mooshammer, Maria; Gentsch, Norman; Mikutta, Robert; Alves, Ricardo J Eloy; Gittel, Antje; Lashchinskiy, Nikolay; Richter, Andreas

2015-01-01

Soil N availability is constrained by the breakdown of N-containing polymers such as proteins to oligopeptides and amino acids that can be taken up by plants and microorganisms. Excess N is released from microbial cells as ammonium (N mineralization), which in turn can serve as substrate for nitrification. According to stoichiometric theory, N mineralization and nitrification are expected to increase in relation to protein depolymerization with decreasing N limitation, and thus from higher to lower latitudes and from topsoils to subsoils. To test these hypotheses, we compared gross rates of protein depolymerization, N mineralization and nitrification (determined using 15N pool dilution assays) in organic topsoil, mineral topsoil, and mineral subsoil of seven ecosystems along a latitudinal transect in western Siberia, from tundra (67°N) to steppe (54°N). The investigated ecosystems differed strongly in N transformation rates, with highest protein depolymerization and N mineralization rates in middle and southern taiga. All N transformation rates decreased with soil depth following the decrease in organic matter content. Related to protein depolymerization, N mineralization and nitrification were significantly higher in mineral than in organic horizons, supporting a decrease in microbial N limitation with depth. In contrast, we did not find indications for a decrease in microbial N limitation from arctic to temperate ecosystems along the transect. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth, even in high-latitude systems such as tundra and boreal forest. Key Points We compared soil N dynamics of seven ecosystems along a latitudinal transectShifts in N dynamics suggest a decrease in microbial N limitation with depthWe found no decrease in microbial N limitation from arctic to temperate zones PMID:26693204

Spatial relationships among cereal yields and selected soil physical and chemical properties.

PubMed

Lipiec, Jerzy; Usowicz, Bogusław

2018-08-15

Sandy soils occupy large area in Poland (about 50%) and in the world. This study aimed at determining spatial relationships of cereal yields and the selected soil physical and chemical properties in three study years (2001-2003) on low productive sandy Podzol soil (Podlasie, Poland). The yields and soil properties in plough and subsoil layers were determined at 72-150 points. The test crops were: wheat, wheat and barley mixture and oats. To explore the spatial relationship between cereal yields and each soil property spatial statistics was used. The best fitting models were adjusted to empirical semivariance and cross-semivariance, which were used to draw maps using kriging. Majority of the soil properties and crop yields exhibited low and medium variability (coefficient of variation 5-70%). The effective ranges of the spatial dependence (the distance at which data are autocorrelated) for yields and all soil properties were 24.3-58.5m and 10.5-373m, respectively. Nugget to sill ratios showed that crop yields and soil properties were strongly spatially dependent except bulk density. Majority of the pairs in cross-semivariograms exhibited strong spatial interdependence. The ranges of the spatial dependence varied in plough layer between 54.6m for yield×pH up to 2433m for yield×silt content. Corresponding ranges in subsoil were 24.8m for crop yield×clay content in 2003 and 1404m for yield×bulk density. Kriging maps allowed separating sub-field area with the lowest yield and soil cation exchange capacity, organic carbon content and pH. This area had lighter color on the aerial photograph due to high content of the sand and low content of soil organic carbon. The results will help farmers at identifying sub-field areas for applying localized management practices to improve these soil properties and further spatial studies in larger scale. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Viking Lander: subsurface water analyzing probe. [Mars subsoil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, G.J.

1969-10-01

A small terradynamic (soil penetrating) vehicle, to be released from the Viking Lander at an altitude of between 5000 and 6000 feet before the terminal descent on the vernier rockets begins, will implant a sensor package 3 to 5 feet beneath the surface to measure water content of Mars subsoil. As it penetrates the soil, the vehicle separates into a probe which carries the primary instrumentation and a tail section which contains the power supply, secondary sensors, and transmitter and antenna assembly. The two sections remain linked by a hard wire umbilical which provides for power and data flow betweenmore » the sections. After impact, a soil moisture subsystem would be activated to gather approximately 100 milligrams of soil at the depth of the penetrating probe. After the mass of the sample is measured, its water content would be determined by heating in a sealed known volume and measuring the dew point of the resulting water vapor with a specular reflection dew point indicator. The penetrating probe and the tail section each contain a pair of aluminum oxide hygrometer elements and one sensistor temperature sensor which, on request by an on-board programmer will measure temperature and absolute water content of the vapor phase in equilibrium with the surrounding soil. Once each 8 hours, the digitized output of the sensors would be transmitted by the RF link to the Lander. This apparatus is expected to measure the water vapor in equilibrium with the soil water in concentrations as low as 0.01 microgram per liter at --60/sup 0/C and absolute soil water in amounts as small as 10 micrograms per gram of soil. A radioisotope power supply would provide an expected life for this instrumentation package in excess of the proposed 90-day mission for the Mars Viking Lander.« less

Magnetic properties of alluvial soils polluted with heavy metals

NASA Astrophysics Data System (ADS)

Dlouha, S.; Petrovsky, E.; Boruvka, L.; Kapicka, A.; Grison, H.

2012-04-01

Magnetic properties of soils, reflecting mineralogy, concentration and grain-size distribution of Fe-oxides, proved to be useful tool in assessing the soil properties in terms of various environmental conditions. Measurement of soil magnetic properties presents a convenient method to investigate the natural environmental changes in soils as well as the anthropogenic pollution of soils with several risk elements. The effect of fluvial pollution with Cd, Cu, Pb and Zn on magnetic soil properties was studied on highly contaminated alluvial soils from the mining/smelting district (Příbram; CZ) using a combination of magnetic and geochemical methods. The basic soil characteristics, the content of heavy metals, oxalate, and dithionite extractable iron were determined in selected soil samples. Soil profiles were sampled using HUMAX soil corer and the magnetic susceptibility was measured in situ, further detailed magnetic analyses of selected distinct layers were carried out. Two types of variations of magnetic properties in soil profiles were observed corresponding to indentified soil types (Fluvisols, and Gleyic Fluvisols). Significantly higher values of topsoil magnetic susceptibility compared to underlying soil are accompanied with high concentration of heavy metals. Sequential extraction analysis proved the binding of Pb, Zn and Cd in Fe and Mn oxides. Concentration and size-dependent parameters (anhysteretic and isothermal magnetization) were measured on bulk samples in terms of assessing the origin of magnetic components. The results enabled to distinguish clearly topsoil layers enhanced with heavy metals from subsoil samples. The dominance of particles with pseudo-single domain behavior in topsoil and paramagnetic/antiferromagnetic contribution in subsoil were observed. These measurements were verified with room temperature hysteresis measurement carried out on bulk samples and magnetic extracts. Thermomagnetic analysis of magnetic susceptibility measured on magnetic extracts indicated the presence of magnetite/maghemite in the uppermost layers, and strong mineralogical transformation of iron oxyhydroxides during heating. Magnetic techniques give valuable information about the soil Fe oxides, which are useful for investigation of the environmental effects in soil. Key words: magnetic methods, Fe oxides, pollution, alluvial soils.

Soil architecture relationships with dynamic soil physical processes: a conceptual study using natural, artificial, and 3D-printed soil cores

NASA Astrophysics Data System (ADS)

Lamandé, Mathieu; Schjønning, Per; Dal Ferro, Nicola; Morari, Francesco

2017-04-01

Pore system architecture is a key feature for understanding physical, biological and chemical processes in soils. Development of visualisation technics, especially x-ray CT, during recent years has been useful in describing the complex relationships between soil architecture and soil functions. We believe that combining visualization with physical models is a step further towards a better understanding of these relationships. We conducted a concept study using natural, artificial and 3D-printed soil cores. Eight natural soil cores (100 cm3) were sampled in a cultivated stagnic Luvisol at two depths (topsoil and subsoil), representing contrasting soil pore systems. Cylinders (100 cm3) were produced from plastic or from autoclaved aerated concrete. Holes of diameters 1.5 and 3 mm were drilled in the cylinder direction for the plastic cylinder and for one of the AAC cylinders. All natural and artificial cores were scanned in a micro x-ray CT scanner at a resolution of 35 µm. The reconstructed image of each soil core was printed with 3D multijet printing technology at a resolution of 29 µm. In some reconstructed digital volumes of the natural soil cores, pores of different sizes (equivalent diameter of 35, 70, 100, and 200 µm) were removed before additional 3D printing. Effective air-filled porosity, Darcian air permeability, and oxygen diffusion were measured on all natural, artificial and printed cores. The comparison of the natural and the artificial cores emphasized the difference in pore architecture between topsoil (sponge like) and subsoil (dominated by large vertical macropores). This study showed the high potential of using printed soil cores for understanding soil pore functions. The results confirm the suitability of the Ball model partitioning the pore system into arterial, marginal and remote pores to describe effects of soil structure on gas transport.

Local seismic hazard assessment in explosive volcanic settings by 3D numerical analyses

NASA Astrophysics Data System (ADS)

Razzano, Roberto; Pagliaroli, Alessandro; Moscatelli, Massimiliano; Gaudiosi, Iolanda; Avalle, Alessandra; Giallini, Silvia; Marcini, Marco; Polpetta, Federica; Simionato, Maurizio; Sirianni, Pietro; Sottili, Gianluca; Vignaroli, Gianluca; Bellanova, Jessica; Calamita, Giuseppe; Perrone, Angela; Piscitelli, Sabatino

2017-04-01

This work deals with the assessment of local seismic response in the explosive volcanic settings by reconstructing the subsoil model of the Stracciacappa maar (Sabatini Volcanic District, central Italy), whose pyroclastic succession records eruptive phases ended about 0.09 Ma ago. Heterogeneous characteristics of the Stracciacappa maar (stratification, structural setting, lithotypes, and thickness variation of depositional units) make it an ideal case history for understanding mechanisms and processes leading to modifications of amplitude-frequency-duration of seismic waves generated at earthquake sources and propagating through volcanic settings. New geological map and cross sections, constrained with recently acquired geotechnical and geophysical data, illustrate the complex geometric relationships among different depositional units forming the maar. A composite interfingering between internal lacustrine sediments and epiclastic debris, sourced from the rim, fills the crater floor; a 45 meters thick continuous coring borehole was drilled in the maar with sampling of undisturbed samples. Electrical Resistivity Tomography surveys and 2D passive seismic arrays were also carried out for constraining the geological model and the velocity profile of the S-waves, respectively. Single station noise measurements were collected in order to define natural amplification frequencies. Finally, the nonlinear cyclic soil behaviour was investigated through simple shear tests on the undisturbed samples. The collected dataset was used to define the subsoil model for 3D finite difference site response numerical analyses by using FLAC 3D software (ITASCA). Moreover, 1D and 2D numerical analyses were carried out for comparison purposes. Two different scenarios were selected as input motions: a moderate magnitude (volcanic event) and a high magnitude (tectonic event). Both earthquake scenarios revealed significant ground motion amplification (up to 15 in terms of spectral acceleration at about 1 s) essentially related to 2D/3D phenomena associated to sharp lateral variations of mechanical properties within the Stracciacappa maar. Our results are relevant to face the assessment of local seismic response in similar volcanic settings in highly urbanised environments elsewhere.

Soil magnetic susceptibility mapping as a pollution and provenance tool: an example from southern New Zealand

NASA Astrophysics Data System (ADS)

Martin, A. P.; Ohneiser, C.; Turnbull, R. E.; Strong, D. T.; Demler, S.

2018-02-01

The presence or absence, degree and variation of heavy metal contamination in New Zealand soils is a matter of ongoing debate as it affects soil quality, agriculture and human health. In many instances, however, the soil heavy metal concentration data do not exist to answer these questions and the debate is ongoing. To address this, magnetic susceptibility (a common proxy for heavy metal contamination) values were measured in topsoil (0-30 cm) and subsoil (50-70 cm) at grid sites spaced at 8 km intervals across ca. 20 000 km2 of southern New Zealand. Samples were measured for both mass- and volume-specific magnetic susceptibility, with results being strongly, positively correlated. Three different methods of determining anomalies were applied to the data including the topsoil-subsoil difference method, Tukey boxplot method and geoaccumulation index method, with each method filtering out progressively more anomalies. Additional soil magnetic (hysteresis, isothermal remanence and thermomagnetic) measurements were made on a select subset of samples from anomalous sites. Magnetite is the dominant remanence carrying mineral, and magnetic susceptibility is governed by that minerals concentration in soils, rather than mineral type. All except two anomalous sites have a dominant geogenic source (cf. anthropogenic). By proxy, heavy metal contamination in southern New Zealand soils is minimal, making them relatively pristine. The provenance of the magnetic minerals in the anomalous sites can be traced back to likely sources in outcrops of igneous rocks within the same catchment, terrane or rock type: a distance of <100 km but frequently <1 km. Soil provenance is a key step when mapping element or isotopic distribution, vectoring to mineralization or studying soil for agricultural suitability, water quality or environmental regulation. Measuring soil magnetic susceptibility is a useful, quick and inexpensive tool that usefully supplements soil geochemical data.

Multichannel Analysis of Surface Waves and Down-Hole Tests in the Archeological "Palatine Hill" Area (Rome, Italy): Evaluation and Influence of 2D Effects on the Shear Wave Velocity

NASA Astrophysics Data System (ADS)

Di Fiore, V.; Cavuoto, G.; Tarallo, D.; Punzo, M.; Evangelista, L.

2016-05-01

A joint analysis of down-hole (DH) and multichannel analysis of surface waves (MASW) measurements offers a complete evaluation of shear wave velocity profiles, especially for sites where a strong lateral variability is expected, such as archeological sites. In this complex stratigraphic setting, the high "subsoil anisotropy" (i.e., sharp lithological changes due to the presence of anthropogenic backfill deposits and/or buried man-made structures) implies a different role for DH and MASW tests. This paper discusses some results of a broad experimental program conducted on the Palatine Hill, one of the most ancient areas of the city of Rome (Italy). The experiments were part of a project on seismic microzoning and consisted of 20 MASW and 11 DH tests. The main objective of this study was to examine the difficulties related to the interpretation of the DH and MASW tests and the reliability limits inherent in the application of the noninvasive method in complex stratigraphic settings. As is well known, DH tests provide good determinations of shear wave velocities (Vs) for different lithologies and man-made materials, whereas MASW tests provide average values for the subsoil volume investigated. The data obtained from each method with blind tests were compared and were correlated to site-specific subsurface conditions, including lateral variability. Differences between punctual (DH) and global (MASW) Vs measurements are discussed, quantifying the errors by synthetic comparison and by site response analyses. This study demonstrates that, for archeological sites, VS profiles obtained from the DH and MASW methods differ by more than 15 %. However, the local site effect showed comparable results in terms of natural frequencies, whereas the resolution of the inverted shear wave velocity was influenced by the fundamental mode of propagation.

Divisions S-4 - soil fertility and plant nutrition: residual value of lime and leaching of calcium in a kaolinitic ultisol in the high rainfall tropics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friesen, D.K.; Juo, A.S.R.; Miller, M.H.

1982-01-01

A long-term experiment was conducted on a highly acidic (pH 4.6), coarse-textured Ultisol in the high rainfall region of southeastern Nigeria in order to evaluate the requirement for and residual value of lime (Ca(OH)/sub 2/) to a continuous crop rotation, and to determine the fate of applied Ca in the soil profile. The initial lime rates used were 0, 0.5, 1, 2, and 4 t of Ca(OH)/sub 2/ per hectare. Maize (Zea mays) was planted in the first season and cowpea (Vigna unguiculata) in the second season under a no-tillage, stubble conservation system. Relatively low rates of lime are adequatemore » to sustain yields in a continuous maize-cowpea rotation system. Liming at a rate of 0.5 t/ha maintained maize yield near maximum for 2 years after application. Sustained maize yields for 5 years or more were possible with a lime rate of 2 t/ha. Cowpeas performed well and showed strong tolerance to soil acidity when planted as a late second-season crop after maize without additional fertilizer application. The critical level of exchangeable Al ranged from 25 to 55% depending upon rate of chemical fertilizer as well as cowpea variety used. Leaching losses of Ca from the surface soil during the first 3 years were <0.5 t/ha of Ca(OH)/sub 2/-equivalents in the 0- to 2-t/ha treatments. Exchangeable-Al saturation in all subsoil layers of all treatments 3 years after liming exceeded 40% and soil pH (H/sub 2/O) was <4.3 indicating that lime was leached as neutral Ca salts and had little effect in ameliorating subsoil acidity. 17 references, 5 figures, 5 tables.« less

Reductive solubilization of arsenic in a mining-impacted river floodplain: Influence of soil properties and temperature.

PubMed

Simmler, Michael; Bommer, Jérôme; Frischknecht, Sarah; Christl, Iso; Kotsev, Tsvetan; Kretzschmar, Ruben

2017-12-01

Mining activities have contaminated many riverine floodplains with arsenic (As). When floodplain soils become anoxic under water-saturated conditions, As can be released from the solid phase. Several microbially-driven As solubilization processes and numerous influential factors were recognized in the past. However, the interplay and relative importance of soil properties and the influence of environmental factors such as temperature remain poorly understood, especially considering the (co)variation of soil properties in a floodplain. We conducted anoxic microcosm experiments at 10, 17.5, and 25 °C using 65 representative soils from the mining-impacted Ogosta River floodplain in Bulgaria. To investigate the processes of As solubilization and its quantitative variation we followed the As and Fe redox dynamics in the solid and the dissolved phase and monitored a range of other solution parameters including pH, Eh, dissolved organic C, and dissolved Mn. We related soil properties to dissolved As observed after 20 days of microcosm incubation to identify key soil properties for As solubilization. Our results evidenced reductive dissolution of As-bearing Fe(III)-oxyhydroxides as the main cause for high solubilization. The availability of nutrients, most likely organic C as the source of energy for microorganisms, was found to limit this process. Following the vertical nutrient gradient common in vegetated soil, we observed several hundred μM dissolved As after 1-2 weeks for some topsoils (0-20 cm), while for subsoils (20-40 cm) with comparable total As levels only minor solubilization was observed. While high Mn contents were found to inhibit As solubilization, the opposite applied for higher temperature (Q 10 2.3-6.1 for range 10-25 °C). Our results suggest that flooding of nutrient-rich surface layers might be more problematic than water-saturation of nutrient-poor subsoil layers, especially in summer floodings when soil temperature is higher than in winter or spring. Copyright © 2017 Elsevier Ltd. All rights reserved.

BeTemper: thermal characterisation of the Belgian subsoil for shallow geothermal applications

NASA Astrophysics Data System (ADS)

Petitclerc, Estelle; Dusar, Michiel; Declercq, Pierre-Yves; Vanbrabant, Yves

2015-04-01

The current energy transition towards Renewable Energy Sources (RES) is mainly driven in Belgium by intermittent sources such as wind turbines and photovoltaic panels. Other sources are however available, such as biomass and geothermal resources. The latter can take various forms among which Ground Source Heat Pumps (GSHP). This Geothermal RES could be an important supply for the heating/cooling market, which represents 48% of the energy consumption in Belgium. The interest in using the ground as a source or storage device for thermal energy has grown considerably in the last few years and the market is expected to grow significantly by 2020 (Petitclerc, 2013). However, research in the thermal characteristics of the soil and subsoil is lagging behind the industrial technological development. Sizing errors of installations increasing the budget are therefore frequent and promising projects are abandoned. BeTemper was launched in 2014 for a period of 2 years. It aims to assess the shallow geothermal potential in Belgium through analysis of rock thermal properties from the surface to a depth of 150 m, which covers the standard depth for a vertical loop system currently installed in Belgium (75% of the GSHP market). The project focuses on laboratory thermal properties analyses (thermal conductivity (λ in W/m.K) and diffusivity (m²/s)) of about 400 rock samples corresponding to 30 different lithologies. Influences of water content, of porosity, of mineralogical composition and of mineralogical texture on these thermal parameters are studied. Thermal parameters measurements are performed with the high-resolution Thermal Conductivity Scanning method (Popov 1999, 2012) for both saturated and dry conditions. The mineralogical and petrological analyses are conducted thanks to different analytical equipments of the mineralogical and petrological laboratory at the RBINS-GSB. The proportion of the different mineralogical phases of samples are evaluated with the Panalytical X-ray Diffraction equipment, while the EDS (Energy-Dispersive X-ray Spectroscopy) and EBSD (Electron BackScattered Diffraction) modules is applied in order to evaluate the chemical and micro-textural content. Special attention is given to lithologies having a variable λ values to assess the influence of porosity and/or minor mineralogical phases on the heat transfer. The sample selection is conducted in order to be representative of the various lithologies composing the Belgian subsoil, taking into account their mineralogical composition, petrological texture along with their degree of alteration. A special emphasis is given to densely populated areas (eg. Sambre & Meuse valleys and large cities of Flanders). with the highest geothermal demands. Petitclerc, E., Dusar, M., Declercq, P-Y., Hoes, H., Laenen, B., Dagrain,F., Vanbrabant, Y., 2013. Overview and perspectives on shallow geothermal energy in Belgium. Proceedings SG6-12, EGC2013, Pisa, June 2013. Popov, Y., Bayuk, I., Parshin, A., Miklashevskiy, D., Novikov, S., Chekhonin, E., 2012. New methods and instruments for determination of reservoir thermal properties. Thirty-Seventh Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, January 30 - February 1, 2012. SGP-TR-194. Popov, Y., Pribnow, D.F.C., Sass, J.H, Williams, C., Burkhardt, H., 1999. Characterization of rock thermal conductivity by high-resolution optical scanning. Geothermics 28, pp 253-276.

Does plant diversity affect the water balance of established grassland systems?

NASA Astrophysics Data System (ADS)

Leimer, Sophia; Bischoff, Sebastian; Blaser, Stefan; Boch, Steffen; Busch, Verena; Escher, Peter; Fischer, Markus; Kaupenjohann, Martin; Kerber, Katja; Klaus, Valentin; Michalzik, Beate; Prati, Daniel; Schäfer, Deborah; Schmitt, Barbara; Schöning, Ingo; Schwarz, Martin T.; Siemens, Jan; Thieme, Lisa; Wilcke, Wolfgang

2017-04-01

The water cycle drives nutrient cycles and plant productivity. The impact of land use on the water cycle has been extensively studied and there is experimental evidence that biodiversity modifies the water cycle in grasslands. However, the combined influences of land-use and associated biodiversity on the water cycle in established land-use systems are unclear. Therefore, we investigated how evapotranspiration (ETa), downward water flux (DF), and capillary rise (CR) in topsoil and subsoil are related to land-use and plant diversity in established, commercially managed grassland and compared these results to findings from experiments where plant diversity was manipulated. In three Central European regions ("Biodiversity Exploratories"), we studied 29 grassland plots (50 m x 50 m; 9-11 plots per region) from 2010 to 2015. The land-use types cover pasture, mown pasture, and meadow in at least triplicate per region. On each plot, we measured soil water contents, meteorological data (hourly resolution), cumulative precipitation (biweekly), plant species richness, the number of plants in the functional groups of grasses, herbs, and legumes (annually), and root biomass (once). Potential evapotranspiration (ETp) was calculated from meteorological data per plot. Missing data points of ETp and soil water contents were estimated with Bayesian hierarchical models. ETa, DF, and CR were calculated for two soil layers with a soil water balance model. The model is based on changes in soil water storage between subsequent observation dates and ETp, which was partitioned between soil layers according to root distribution. Water fluxes in annual resolution were statistically analyzed for land-use and biodiversity effects using repeated-measures analysis of variance (ANOVA). Land-use type did not affect water fluxes. Species richness did not influence DF and CR. DF from topsoil was higher on plots with more grass species, which is opposite to the results from a manipulative biodiversity experiment. The number of grasses and herbs influenced CR into topsoil. ETa from topsoil decreased with increasing species richness while ETa from subsoil increased. Opposing effects on ETa in the two soil layers were also observed for the numbers of herb and legume species. In manipulative biodiversity experiments, opposing effects on ETa from different soil layers are explained by higher plant cover and biomass in species-rich mixtures, reducing evaporation by shading of the topsoil, and deeper roots in species-rich mixtures, facilitating water use and increasing transpiration from subsoil. In our study, biomass decreased with increasing species richness because fertilizer application increased biomass production and decreased species richness. Plots with more grasses showed lower ETa from topsoil than plots with less grasses. However, the within-subject effects indicated higher ETa from topsoil in years with more grasses on individual plots than in years with less grasses. The latter finding complies with the results from a manipulative biodiversity experiment, which has homogeneous soil properties and management. The opposite between-subject effect is probably caused by variations in environmental conditions between plots. This indicates that processes controlling the biodiversity-water cycle relationship vary in real-world systems with environmental conditions, which are largely controlled for in manipulative biodiversity experiments.

Effects of flooding on phosphorus and iron mobilization in highly weathered soils: Short-term effects and mechanisms

NASA Astrophysics Data System (ADS)

Maranguit, Deejay

2017-04-01

The strong affinity of phosphorus (P) to iron (Fe) oxides and hydroxides in highly weathered tropical soils limits P availability and therefore plant productivity. In flooded soils, however, P fixed by Fe oxides and hydroxides can be released and transformed to a more available form because of Fe3+ reduction to Fe2+. These P dynamics in flooded soils are well documented for rice paddies. Such effects are much less studied in other land-use types under the influence of seasonal flooding, especially in the tropics during heavy monsoon rains. The aim of this study was to investigate the mobilization of P during flooding leading to anaerobic conditions in topsoil and subsoil horizons depending on land-use type. Samples were collected in highly weathered soils from four replicate sites under natural rainforest, jungle rubber, rubber and oil palm plantations in Sumatra, Indonesia. Topsoil and subsoil were taken to ensure a wide range of soil organic matter (SOM) and P contents. Soils were incubated under anaerobic, flooded conditions at 30 ± 1 oC for 60 days. Our results confirmed the hypothesis that soil flooding mobilizes P and increases P availability. Two distinct and opposite phases, however, were observed upon flooding. During the first three weeks of flooding, the dissolved P (DP) concentration peaked, simultaneously with a peak of dissolved Fe2+ (DFe2+) and dissolved organic carbon (DOC) in the soil solution. After three weeks, P availability in soils decreased, although Fe-P and available P did not reach initial, pre-flooding levels. Accordingly, Fe dissolution and P mobilization were reversible processes. Furthermore, land-use type influenced the impacts of flooding on P and Fe forms mainly in the topsoil, where P dissolution and availability were generally higher under forest and, to a lesser extent, under jungle rubber. A positive correlation between DOC and DFe2+ (R2 = 0.42) in topsoil indicates that the intensity of microbially-mediated Fe3+ reduction is limited by the amount of available carbon (C) as an energy source for microorganisms. Moreover, microbial mineralization of organic P from SOM also increases P availability, and this process requires available C. This interpretation was supported by the strong correlation (R2 = 0.58) between available P and DOC, as well as between DP and DOC (R2 = 0.56) in topsoil. The increasing soil solution pH in topsoil and subsoil after flooding of all land-use types may also influence the P release over time. In summary, the increase of available P and DP during flooding is due to three main mechanisms: (1) P release via the microbially-mediated reductive dissolution of Fe3+ oxides; (2) P release during SOM mineralization and (3) solubility of Fe phosphate due to increasing pH. These mechanisms are relevant not only in riparian areas, where flooding occurs, but also in well-drained soil that is partly waterlogged after regular heavy rainfalls during the wet season. Likewise, the P cycle turnover is faster in compacted, often anaerobic plantation soils. Here, more P is pumped by the vegetation and then removed from plantations due to yield export.

Relationships between soil moisture-holding properties and soil texture, organic matter content, and bulk density

NASA Technical Reports Server (NTRS)

Riley, H. C. F.

1981-01-01

Specimens from the surface horizon and the subsoil of 62 soil horizons in Hedmark and Oppland were investigated to study how the mechanical composition of the soil, the organic matter content and the bulk density affect their porosity and air capacity and their total and available water content. Most of the specimens belonged to the loam group, and a smaller number was from sandy and silty types of soil. Equations were established to make it possible to calculate the water retention curves and the amount of available water from the above mentioned parameters. As a rule, errors derived from the equations are no greater than those which are found in similar research in other countries.

Leaching behaviour of coal-ash: a case study.

PubMed

Hajarnavis, M R; Bhide, A D

2003-10-01

Leaching of trace elements from fly ash dumps to subsoil layer due to the rain water results in contamination of ground water. The ground water pollution due to fly ash deposition on land so occurring was assessed by simulating the disposal site conditions using two lysimeter with two different soils. Leachate was collected and analysed daily to help understand the phenomenon of leaching of fly-ash constituents in the environment. The trace metals and physico-chemical parameters of fly ash and soil used were measured before and after the experiment. Results of analysis of soil and fly ash samples were then compared with the results of lysimeter-I and lysimeter-II. The study reveals that metals respond differently at dumping site while reacting with soil and water.

Hydrocarbon degradation in soils and methods for soil biotreatment.

PubMed

Morgan, P; Watkinson, R J

1989-01-01

The cleanup of soils and groundwater contaminated with hydrocarbons is of particular importance in minimizing the environmental impact of petroleum and petroleum products and in preventing contamination of potable water supplies. Consequently, there is a growing industry involved in the treatment of contaminated topsoils, subsoils, and groundwater. The biotreatment methodologies employed for decontamination are designed to enhance in situ degradation by the supply of oxygen, inorganic nutrients, and/or microbial inocula to the contaminated zone. This review considers the fate and effects of hydrocarbon contaminants in terrestrial environments, with particular reference to the factors that limit biodegradation rates. The potential efficiencies, advantages, and disadvantages of biotreatment techniques are discussed and the future research directions necessary for process development are considered.

Optimal Draft requirement for vibratory tillage equipment using Genetic Algorithm Technique

NASA Astrophysics Data System (ADS)

Rao, Gowripathi; Chaudhary, Himanshu; Singh, Prem

2018-03-01

Agriculture is an important sector of Indian economy. Primary and secondary tillage operations are required for any land preparation process. Conventionally different tractor-drawn implements such as mouldboard plough, disc plough, subsoiler, cultivator and disc harrow, etc. are used for primary and secondary manipulations of soils. Among them, oscillatory tillage equipment is one such type which uses vibratory motion for tillage purpose. Several investigators have reported that the requirement for draft consumption in primary tillage implements is more as compared to oscillating one because they are always in contact with soil. Therefore in this paper, an attempt is made to find out the optimal parameters from the experimental data available in the literature to obtain minimum draft consumption through genetic algorithm technique.

Measurement methods of building structures deflections

NASA Astrophysics Data System (ADS)

Wróblewska, Magdalena

2018-04-01

Underground mining exploitation is leading to the occurrence of deformations manifested by, in particular, sloping terrain. The structures situated on the deforming subsoil are subject to uneven subsidence which is leading in consequence to their deflection. Before a building rectification process takes place by, e.g. uneven raising, the structure's deflection direction and value is determined so that the structure is restored to its vertical position as a result of the undertaken remedial measures. Deflection can be determined by applying classical as well as modern measurement techniques. The article presents examples of measurement methods used considering the measured elements of building structures' constructions and field measurements. Moreover, for a given example of a mining area, the existing deflections of buildings were compared with mining terrain sloping.

Sample selection and preservation techniques for the Mars sample return mission

NASA Technical Reports Server (NTRS)

Tsay, Fun-Dow

1988-01-01

It is proposed that a miniaturized electron spin resonance (ESR) spectrometer be developed as an effective, nondestructivew sample selection and characterization instrument for the Mars Rover Sample Return mission. The ESR instrument can meet rover science payload requirements and yet has the capability and versatility to perform the following in situ Martian sample analyses: (1) detection of active oxygen species, and characterization of Martian surface chemistry and photocatalytic oxidation processes; (2) determination of paramagnetic Fe(3+) in clay silicate minerals, Mn(2+) in carbonates, and ferromagnetic centers of magnetite, maghemite and hematite; (3) search for organic compounds in the form of free radicals in subsoil, and detection of Martian fossil organic matter likely to be associated with carbonate and other sedimentary deposits. The proposed instrument is further detailed.

Effect of land-use change on soil organic carbon stocks in the Eastern Usambara Mountain (Tanzania)

NASA Astrophysics Data System (ADS)

Kirsten, Maximilian; Kaaya, Abel; Klinger, Thomas; Feger, Karl-Heinz

2014-05-01

A soil organic carbon (SOC) inventory, covering 10 sites with 5 different land-use systems (primary forest, secondary forest, tea plantation, home garden, and cropland) was conducted in the tropical monsoonal Eastern Usambara Mountains (EUM), NE Tanzania. At all sites the environmental factors such as climate and parent material, for soil formation (gneiss), as well as elevation and slope position are highly comparable. The evergreen submontane primary rain forest, which still exists in vast areas in the EUM and the well-known land-use history there provide nearly optimal conditions for the assessment of land-use change effects on soil properties, notably the SOC stocks. We collected horizon-wise samples from soil pit profiles. In addition, samples from fixed depth-intervals were taken from 8 augering points located systematically around each soil pit. The sampling scheme yielded a unique set of soil information (pedological, chemical, and physical) that favours a reliable assessment of SOC stocks and future analytical work on SOM quality and binding mechanisms. The investigated soils are characterized by high clay contents, which increase with depth. Soil pH varies between 3.5 and 5.4 over all land-use systems and horizons, higher pH values could be detected for the agricultural systems in the topsoil, the differences between agricultural and forest systems decrease in the subsoil. The potential cation exchange capacity is in most cases < 24 cmolc kg-1, furthermore the base saturation is always < 50 % in the subsoil. Thus, based on that analytical data all soils can be classified as Acrisols revealing the high comparability of the investigated sites. This is an excellent prerequisite for the 'false chronosequence' approach applied. Organic carbon (C) stocks in the soils from the investigated land-use systems cover a wide range between 17.1 and 24.2 kg m-2 (0-100 cm). Variability is even high in the subset of the 3 primary forests. Statistically significant differences between the forest and cropland systems occur in the uppermost depth interval 0-10 cm. Furthermore, the primary forests have higher, but not significantly different SOC stocks in the topsoil (0-40 cm) compared with the cropland systems. In all investigated soils the SOC stocks for the entire soil profiles (0-100 cm) are in a narrow range. This may give a hint on SOC relocation from the topsoil to the subsoil when forests were converted to cropland systems. Our results reveal that this land-use change has led to a shift in above- and belowground litter distribution and amount. Also slash and burn practises as well as burning of plant residues in arable farming are common in the EUM. Both phenomena may control SOC relocation as they are associated with a changed C input and/or the formation of C compounds that can be relocated in the profile. In all investigated soils high concentrations of dithionite- and oxalate- extractable iron and aluminum were analyzed. Hence, interaction of SOC with oxides formed by the two metals is here probably one of the main stabilization mechanisms of SOC. The relocation and stabilization processes of SOC are the key functions for the implementation of sustainable agriculture in the EUM, and the conducted study provide a suitable basis for our ongoing research in this region of the wet tropics of Africa.

Carbon stabilization mechanisms in soils in the Andes

NASA Astrophysics Data System (ADS)

Jansen, Boris; Cammeraat, Erik

2015-04-01

The volcanic ash soils of the Andes contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute significant potential sources or sinks of the greenhouse gas CO2. Climate and/or land use change potentially have a strong effect on these large SOM stocks. To clarify the role of chemical and physical stabilisation mechanisms in volcanic ash soils in the montane tropics, we investigated carbon stocks and stabilization mechanisms in the top- and subsoil along an altitudinal transect in the Ecuadorian Andes. The transect encompassed a sequence of paleosols under forest and grassland (páramo), including a site where vegetation cover changed in the last century. We applied selective extraction techniques, performed X-ray diffraction analyses of the clay fraction and estimated pore size distributions at various depths in the top- and subsoil along the transect. In addition, from several soils the molecular composition of SOM was further characterized with depth in the current soil as well as the entire first and the top of the second paleosol using GC/MS analyses of extractable lipids and Pyrolysis-GC/MS analyses of bulk organic matter. Our results show that organic carbon stocks in the mineral soil under forest a páramo vegetation were roughly twice as large as global averages for volcanic ash soils, regardless of whether the first 30cm, 100cm or 200cm were considered. We found the carbon stabilization mechanisms involved to be: i) direct stabilization of SOM in organo-metallic (Al-OM) complexes; ii) indirect protection of SOM through low soil pH and toxic levels of Al; and iii) physical protection of SOM due to a very high microporosity of the soil (Tonneijck et al., 2010; Jansen et al. 2011). When examining the organic carbon at a molecular level, interestingly we found extensive degradation of lignin in the topsoil while extractable lipids were preferentially preserved in the subsoil (Nierop and Jansen, 2009). Both vegetation types contributed to soil acidification, thus increasing SOM accumulation and inducing positive feedbacks. While carbon stocks in the mineral soil were roughly equivalent under forest and páramo vegetation, a significant amount of additional carbon were stored in exceptionally large ecto-organic layers of up to a meter thick under forest vegetation that are absent under páramo. In our presentation we will further elaborate these results and place them in the context of SOM turnover under climate and/or land-use change in the broader Andean region, including a comparison with SOM dynamics in non-volcanic soils as present in the Peruvian púna systems. Jansen, B., Tonneijck, F.H. and Verstraten, J.M., 2011. Selective Extraction Methods to Discern Fractions of Aluminium, Iron and Organic Carbon in Montane Volcanic Ash Soils, Pedosphere, 21: 549-565. Nierop, K.G.J. and Jansen,B., 2009. Extensive transformation of organic matter and excellent lipid preservation at the upper, superhumid Guandera páramo, Geoderma, 151: 357-369. Tonneijck, F.H., Jansen, B., Nierop, K.G.J. ., Verstraten, J.M., Sevink, J. and De Lange, L., 2010. Carbon stocks and stabilization mechanisms in volcanic ash soils in natural Andean ecosystems of northern Ecuador, European Journal of Soil Science, 61: 392-405.

Time-lapse electrical resistivity tomography: a powerful tool for landslide monitoring?

NASA Astrophysics Data System (ADS)

Perrone, A.

2011-12-01

The extreme rainfall events and the quick snowmelt occurrences play an important role in the triggering of the landslides. The occurrence of one of these factors can determine the variation of water content in the first layers of the subsoil and as a consequence a quick soil saturation inducing both an increase in pore-water pressures and the overloaded of the slopes progressively collapsing. The electrical resistivity, self-potential, electromagnetic induction and GPR methods can be considered as the most appropriate for assessing the presence of water in the underground. Such methods allow us to study the behavior of water content over much wider and deeper areas than those offered by traditional methods (thermo-gravimetric, tensiometric, TDR, etc) based on spot measures and concerning small volumes. In particular, the Electrical Resistivity Tomography (ERT), which has already proved to be a powerful tool both for the geometrical reconstruction of a landslide body (location of sliding surface, estimation of the thickness of the slide material) and the individuation of high water content areas, can be considered as an alternative tool to be employed for a qualitative and quantitative water content monitoring in the first layers of the subsoil. Indeed, time-lapse 2D ERT can be tested in order to gather information on the temporal and spatial patterns of water infiltration processes and water content variation. This work reports the preliminary results from a new prototype system planned to obtain time-lapse 2D ERTs, TDR and precipitation measurements in two landslide areas located in the Southern Apennine chain (Italy). The system was planned with the aim to estimate the variation of the resistivity parameter on a long period considering the water content variation, the rain water infiltration and the seasonal changes. The prototype system, linked to a pc used for storing data and managing the time interval acquisition, consists of: a resistivimeter connected to a multichannel cable, 48 steel electrodes buried in the soil at a depth of about 0.5 m at a distance of 1 or 5 m; a TDR system linked to 4 probes 20 cm length, buried at different depths along the same profile of the geoelectrical one; while a weather station consists of a rain gauge to quantify the amount of rain falling on that area, one sensor to measure the temperature and another to determine the speed and direction of the wind. At the beginning the time-lapse ERT were analysed to verify the functionality and stability of the system and to decide the measurement time intervals. After that, the statistical analysis of the results obtained was performed with the aim to define the water content variation in the first layers of the subsoil, in particular in the vadose zone. The results were compared with the TDR ones and the piezometric measurements were performed in the area thanks to the presence of equipped boreholes. The correlation between the variation of the parameters measured (electrical resistivity, water content and piezometric level) and the rain-gauge measurements was also considered. The preliminary results seem to be encouraged also if the analysis of the data acquired on a longer period could better highlight the capability of the system.

The increase of soil organic carbon as proposed by the "4/1000 initiative" is strongly limited by the status of soil development - A case study along a substrate age gradient in Central Europe.

PubMed

Schiefer, Jasmin; Lair, Georg J; Lüthgens, Christopher; Wild, Eva Maria; Steier, Peter; Blum, Winfried E H

2018-07-01

During COP 21 in Paris 2015, several states and organizations agreed on the "4/1000" initiative for food security and climate. This initiative aims to increase world's soil organic carbon (SOC) stocks by 4‰ annually. The influence of soil development status on SOC dynamics is very important but usually not considered in studies. We analyse SOC accumulation under forest, grassland and cropping systems along a soil age gradient (10-17,000years) to show the influence of soil development status on SOC increase. SOC stocks (0-40cm) and accumulation rates along a chronosequence in alluvial soils of the Danube River in the Marchfeld (eastern Austria) were analysed. The analysed Fluvisols and Chernozems have been used as forest, grassland and cropland for decades or hundreds of years. The results showed that there is a fast build-up of OC stocks (0-40cm) in young soils with accumulation of ~1.3tha -1 a -1 OC in the first 100years and ~0.5tha -1 a -1 OC between 100 and 350years almost independent of land use. Chernozems with a sediment deposition age older than 5.000years have an accumulation rate<0.01tOCha -1 a -1 (0-40cm). Radiocarbon dating showed that the topsoil (0-10cm) consists mainly of ">modern" and "modern" carbon indicating a fast carbon cycling. Carbon in subsoil is less exposed to decomposition and OC can be stored at long-time scales in the subsoil ( 14 C age of 3670±35 BP). In view of the '4/1000' initiative, soils with constant carbon input (forest & grassland) fulfil the intended 4‰ growth rate of SOC stocks only in the first 60years of soil development. We proclaim that under the present climate in Central Europe, the increase of SOC stocks in soil is strongly affected by the state of soil development. Copyright © 2018 Elsevier B.V. All rights reserved.

Leaf responsiveness of Populus tremula and Salix viminalis to soil contaminated with heavy metals and acidic rainwater.

PubMed

Hermle, Sandra; Vollenweider, Pierre; Günthardt-Goerg, Madeleine S; McQuattie, Carolyn J; Matyssek, Rainer

2007-11-01

Fast-growing trees such as Salix viminalis L. and Populus tremula L. are well suited to phytoremediate heavy metal contaminated soils. However, information on tree performance, particularly leaf function, under conditions of heavy metal contamination is scarce. We used yearly coppiced saplings of S. viminalis and P. tremula growing in model ecosytems to test four hypotheses: (1) heavy metal contamination impairs photosynthesis by injuring leaf structure; (2) the effects of heavy metal contamination are enhanced by acidified rainwater and low soil pH; (3) heavy metal contamination increases dark respiration and, thus, repair processes; and (4) heavy metal contamination is tolerated and remediated better by S. viminalis than by P. tremula. We investigated heavy metal accumulation, tissue injury and gas exchange in leaves of plants subjected to controlled soil contamination with heavy metal dust. Additional treatments included acidic and calcareous natural forest subsoils in combination with irrigation with rainwater at pH 5.5 or 3.5. In both provenances of P. tremula that were studied, but not in S. viminalis, heavy metal treatment reduced photosynthesis and transpiration by varying amounts, except in the hot and dry summer of 2003, but had no effect on dark respiration. At light saturation, net CO(2) uptake and water-use efficiency were reduced by heavy metal contamination, whereas the CO(2) concentration in the leaf intercellular air space was increased. Rainwater pH and subsoil pH only slightly modified the effects of the heavy metal treatment on P. tremula. Gas exchange responses of P. tremula to heavy metals were attributed to leaf structural and ultrastructural changes resulting from hypersensitive-response-like processes and accelerated mesophyll cell senescence and necroses in the lower epidermis, especially along the transport pathways of heavy metals in the leaf lamina. Overall, the effects of heavy metals on P. tremula corroborated Hypothesis 1, but refuted Hypotheses 2 and 3, and were inconclusive for Hypothesis 4. Both P. tremula and S. viminalis showed appreciable potential for storing heavy metals in aging foliage.

Losses of soil carbon by converting tropical forest to plantations: erosion and decomposition estimated by δ(13) C.

PubMed

Guillaume, Thomas; Damris, Muhammad; Kuzyakov, Yakov

2015-09-01

Indonesia lost more tropical forest than all of Brazil in 2012, mainly driven by the rubber, oil palm, and timber industries. Nonetheless, the effects of converting forest to oil palm and rubber plantations on soil organic carbon (SOC) stocks remain unclear. We analyzed SOC losses after lowland rainforest conversion to oil palm, intensive rubber, and extensive rubber plantations in Jambi Province on Sumatra Island. The focus was on two processes: (1) erosion and (2) decomposition of soil organic matter. Carbon contents in the Ah horizon under oil palm and rubber plantations were strongly reduced up to 70% and 62%, respectively. The decrease was lower under extensive rubber plantations (41%). On average, converting forest to plantations led to a loss of 10 Mg C ha(-1) after about 15 years of conversion. The C content in the subsoil was similar under the forest and the plantations. We therefore assumed that a shift to higher δ(13) C values in plantation subsoil corresponds to the losses from the upper soil layer by erosion. Erosion was estimated by comparing the δ(13) C profiles in the soils under forest and under plantations. The estimated erosion was the strongest in oil palm (35 ± 8 cm) and rubber (33 ± 10 cm) plantations. The (13) C enrichment of SOC used as a proxy of its turnover indicates a decrease of SOC decomposition rate in the Ah horizon under oil palm plantations after forest conversion. Nonetheless, based on the lack of C input from litter, we expect further losses of SOC in oil palm plantations, which are a less sustainable land use compared to rubber plantations. We conclude that δ(13) C depth profiles may be a powerful tool to disentangle soil erosion and SOC mineralization after the conversion of natural ecosystems conversion to intensive plantations when soils show gradual increase of δ(13) C values with depth. © 2015 The Authors. Global Change Biology published by John Wiley & Sons Ltd.

Drivers for spatial variability in agricultural soil organic carbon stocks in Germany

NASA Astrophysics Data System (ADS)

Vos, Cora; Don, Axel; Hobley, Eleanor; Prietz, Roland; Heidkamp, Arne; Freibauer, Annette

2017-04-01

Soil organic carbon is one of the largest components of the global carbon cycle. It has recently gained importance in global efforts to mitigate climate change through carbon sequestration. In order to find locations suitable for carbon sequestration, and estimate the sequestration potential, however, it is necessary to understand the factors influencing the high spatial variability of soil organic carbon stocks. Due to numerous interacting factors that influence its dynamics, soil organic carbon stocks are difficult to predict. In the course of the German Agricultural Soil Inventory over 2500 agricultural sites were sampled and their soil organic carbon stocks determined. Data relating to more than 200 potential drivers of SOC stocks were compiled from laboratory measurements, farmer questionnaires and climate stations. The aims of this study were to 1) give an overview of soil organic carbon stocks in Germany's agricultural soils, 2) to quantify and explain the influence of explanatory variables on soil organic carbon stocks. Two different machine learning algorithms were used to identify the most important variables and multiple regression models were used to explore the influence of those variables. Models for predicting carbon stocks in different depth increments between 0-100 cm were developed, explaining up to 62% (validation, 98% calibration) of total variance. Land-use, land-use history, clay content and electrical conductivity were main predictors in the topsoil, while bedrock material, relief and electrical conductivity governed the variability of subsoil carbon stocks. We found 32% of all soils to be deeply anthropogenically transformed. The influence of climate related variables was surprisingly small (≤5% of explained variance), while site variables explained a large share of soil carbon variability (46-100% of explained variance), in particular in the subsoil. Thus, the understanding of SOC dynamics at regional scale requires a thorough description of the variability in soil physical parameters. Agronomic management impact on SOC stocks is important near the soil surface, but is mainly attributable to land-use and not to other management factors on this large regional scale. The importance of historical land-use practices as well as anthropogenic soil transformations to SOC stocks highlights the need for prudent soil management and conservation policies.

Source identification and spatial distribution of arsenic and heavy metals in agricultural soil around Hunan industrial estate by positive matrix factorization model, principle components analysis and geo statistical analysis.

PubMed

Zhang, Xiaowen; Wei, Shuai; Sun, Qianqian; Wadood, Syed Abdul; Guo, Boli

2018-09-15

Characterizing the distribution and defining potential sources of arsenic and heavy metals are the basic preconditions for reducing the contamination of heavy metals and metalloids. 71 topsoil samples and 61 subsoil samples were collected by grid method to measure the concentration of cadmium (Cd), arsenic (As), lead (Pb), copper (Cu), zinc (Zn), nickel (Ni) and chromium (Cr). Principle components analysis (PCA), GIS-based geo-statistical methods and Positive Matrix Factorization (PMF) were applied. The results showed that the mean concentrations were 9.59 mg kg -1 , 51.28 mg kg -1 , 202.07 mg kg -1 , 81.32 mg kg -1 and 771.22 mg kg -1 for Cd, As, Pb, Cu and Zn, respectively, higher than the guideline values of Chinese Environmental Quality Standard for Soils; while the concentrations of Ni and Cr were very close to recommended value (50 mg kg -1 , 200 mg kg -1 ), and some site were higher than guideline values. The soil was polluted by As and heavy metals in different degree, which had harmful impact on human health. The results from principle components analysis methods extracted three components, namely industrial sources (Cd, Zn and Pb), agricultural sources (As and Cu) and nature sources (Cr and Ni). GIS-based geo-statistical combined with local conditions further apportioned the sources of these trace elements. To better identify pollution sources of As and heavy metals in soil, the PMF was applied. The results of PMF demonstrated that the enrichment of Zn, Cd and Pb were attributed to industrial activities and their contribution was 24.9%; As was closely related to agricultural activities and its contribution was 19.1%; Cr, a part of Cu and Ni were related to subsoil and their contribution was 30.1%; Cu and Pb came from industry and traffic emission and their contribution was 25.9%. Copyright © 2018 Elsevier Inc. All rights reserved.

Archaeogeophysical tests in water saturated and under water scenarios at the Hydrogeosite Laboratory

NASA Astrophysics Data System (ADS)

Capozzoli, Luigi; De Martino, Gregory; Giampaolo, Valeria; Perciante, Felice; Rizzo, Enzo

2016-04-01

The growing interest in underwater archaeology as witnessed by numerous archaeological campaigns carried out in the Mediterranean region in marine and lacustrine environments involves a challenge of great importance for archaeogeophysical discipline. Through a careful use of geophysical techniques it is possible support archaeological research to identify and analyse the undiscovered cultural heritage placed under water located near rivers and sea. Over the past decades, geophysical methods were applied successfully in the field of archaeology: an integrated approach based on the use of electric, electromagnetic and magnetic techniques have showed the ability to individuate and reconstruct the presence of archaeological remains in the subsoil allowing to define their distribution in the space limiting the excavation activities. Moreover the capability of geophysics could be limited cause the low geophysical contrasts occurring between archaeological structures and surrounding environment; in particular problems of resolution, depth of investigation and sensitivity related to each adopted technique can result in a distorted reading of the subsurface behaviour preventing the identification of archaeological remains. This problem is amplified when geophysical approach is applied in very humid environments such as in lacustrine and marine scenarios, or in soils characterized by high clay content that make more difficult the propagation of geophysical signals. In order to improve our geophysical knowledge in lacustrine and coastal scenarios a complex and innovative research project was realized at the CNR laboratory of Hydrogeosite which permitted to perform an archaeogeophysical experiment in controlled conditions. The designed archaeological context was focused on the Roman age and various elements characterized by different shapes and materials were placed at different depths in the sub-soil. The preliminary project activities with some scenarios were presented last year, now we would like to show the final results of the project where different scenarios were set up for GPR and ERT investigations. Severale phases were performed: buried objects were covered by different thickness of sediments and different soil water contents were defined. Moreover, geophysical measurements were acquired on an underwater scenario. The 2D and 3D acquisitions have allowed to identify the limits and the abilities of the GPR and resistivity measurements.

Monitoring the performance of an alternative cover using caisson lysimeters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waugh, W.J.; Smith, G.M.; Mushovic, P.S.

2004-02-29

The U.S. Department of Energy (DOE) office in Grand Junction, Colorado, and the U.S. Environmental Protection Agency (EPA), Region 8, collaborated on a series of field lysimeter studies to design and monitor the performance of an alternative cover for a uranium mill tailings disposal cell at the Monticello, Utah, Superfund Site. Because groundwater recharge is naturally limited at Monticello in areas with thick loess soils, DOE and EPA chose to design a cover for Monticello using local soils and a native plant community to mimic this natural soilwater balance. Two large drainage lysimeters fabricated of corrugated steel culvert lined withmore » high-density polyethylene were installed to evaluate the hydrological and ecological performance of an alternative cover design constructed in 2000 on the disposal cell. Unlike conventional, lowpermeability designs, this cover relies on (1) the water storage capacity of a 163-cm soil “sponge” layer overlying a sand-and-gravel capillary barrier to retain precipitation while plants are dormant and (2) native vegetation to remove precipitation during the growing season. The sponge layer consists of a clay loam subsoil compacted to 1.65 g/cm2 in one lysimeter and a loam topsoil compacted to 1.45 g/cm2 in the other lysimeter, representing the range of as-built conditions constructed in the nearby disposal cell cover. About 0.1 mm of drainage occurred in both lysimeters during an average precipitation year and before they were planted, an amount well below the EPA target of <3.0 mm/yr. However, the cover with less compacted loam topsoil sponge had a 40% greater water storage capacity than the cover with overly compacted clay loam subsoil sponge. The difference is attributable in part to higher green leaf area and water extraction by plants in the loam topsoil. The lesson learned is that seemingly subtle differences in soil types, sources, and compaction can result in salient differences in performance. Diverse, seeded communities of predominantly native perennial species were established on both lysimeters during an extended 3-yr drought, highlighting the importance of a sound understanding of the local ecology and of implementing the science and methods of disturbed-land revegetation.« less

[Iron ore, economic geology and networks of experts between Wisconsin and the state of Minas Gerais, 1881-1914].

PubMed

Fischer, Georg

2014-01-01

This article deals with the "discovery" of Brazilian iron ore from two perspectives. The first examines the increasing emphasis of the geosciences and their practical application and global reach since the second half of the nineteenth century. While in Brazil economic geology was integrated step by step into state institutions, at the global level it experienced its moment of triumph with the 11th International Geological Congress in 1910. The second deals with a specific social network with a decisive role in the race for Brazilian iron ore: with transnational experts juggling between the logic of the market and that of the academy. The article reveals the importance of local negotiations in the incorporation of the subsoil of Minas Gerais into the global space of mining.

Growing trees on completed sanitary landfills. [Nyssa sylvatica, Picea abies, Ginkgo biloba

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leone, I.A.; Gilman, E.F.; Flower, F.B.

1983-01-01

A 10-year old completed landfill in New Jersey consisting of 9 m (depth) of refuse covered with 15-25 cm of soil was cleared of debris and vegetation and covered with 30 cm of subsoil and 15-25 cm of topsoil. Nineteen coniferous and broadleaved species were planted on the landfill and on a control site in 1975, and trees were maintained and growth and condition monitored over 4 years. On the basis of shoot length and stem area increase, the most successful of the surviving trees were Nyssa sylvatica, Picea abies and Ginkgo biloba, in decreasing order of tolerance. Tolerance ofmore » landfill conditions appeared to be greatest in those species with low water requirements, a slow growth rate, high acid tolerance and a shallow root system. (Refs. 11).« less

Geochemical patterns in soils in and around Siddipet, Medak District, Andhra Pradesh, India.

PubMed

Dantu, Sujatha

2010-11-01

This paper reports the first results of geochemical survey carried out in and around Siddipet, taking soil (topsoil 0-25 cm and subsoil 70-95 cm) as the sampling media. The data were obtained in a consistent way from 61 sites. The samples were analyzed for 29 elements (As, Ba, Cd, Co, Cr, Cu, F, Mo, Ni, Pb, Rb, Se, Sr, Th, U, V, Y, Zn, Zr, Si, Al, Fe, Mn, Mg, Ca, Na, K, Ti, and P) by X-ray fluorescence spectrometer, and baseline levels for these elements are presented. Results reveal that the correlation between the geochemical patterns in the soils developed on different litho-variants is not straight forward, but some general trends can be observed. Regional parent materials and pedogenesis are the primary factors influencing the concentrations of trace elements while anthropogenic activities have secondary influence.

Sewage sludge as conditioner for improving soils affected by sulfur dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, M.K.

1979-12-01

Continuous emission of SO/sub 2/ from the acid manufacturing plant at Ching Lung Tau, New Territorise of Honk Kong, damaged most of the surrounding vegetation, leaving only a few comparatively more resistant species, e.g. Eragrostis sp., Ischaemum aristatum, Smilax glabra, etc. Erosion occurred after heavy rainfall. Fine particles were washed away, leaving the non-fertile subsoil which lack nutrients. The utilization of sludge as a soil conditioner has been regarded as a method of sludge disposal which not only solves some of the pollution problems but receives benefit from the waste product. A considerable amount of literature has been concerned withmore » improving infertile soil including the reclamation of spoiled land, e.g. coal mine spoils, iron-ore tailing. The present investigation attempts to study the effect of applying digested sewage sludge to eroded soil using laboratory soil columns and a green house trial.« less

The Analysis of Soil Resistance During Screw Displacement Pile Installation

NASA Astrophysics Data System (ADS)

Krasinski, Adam

2015-02-01

The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

Properties of lightweight cement-based composites containing waste polypropylene

NASA Astrophysics Data System (ADS)

Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

2016-07-01

Improvement of buildings thermal stability represents an increasingly important trend of the construction industry. This work aims to study the possible use of two types of waste polypropylene (PP) for the development of lightweight cement-based composites with enhanced thermal insulation function. Crushed PP waste originating from the PP tubes production is used for the partial replacement of silica sand by 10, 20, 30, 40 and 50 mass%, whereas a reference mixture without plastic waste is studied as well. First, basic physical and thermal properties of granular PP random copolymer (PPR) and glass fiber reinforced PP (PPGF) aggregate are studied. For the developed composite mixtures, basic physical, mechanical, heat transport and storage properties are accessed. The obtained results show that the composites with incorporated PP aggregate exhibit an improved thermal insulation properties and acceptable mechanical resistivity. This new composite materials with enhanced thermal insulation function are found to be promising materials for buildings subsoil or floor structures.

Spectral measurements of Terrestrial Mars Analogues: support for the ExoMars - Ma_Miss instrument

NASA Astrophysics Data System (ADS)

De Angelis, S.; De Sanctis, M. C.; Ammannito, E.; Di Iorio, T.; Carli, C.; Frigeri, A.; Capria, M. T.; Federico, C.; Boccaccini, A.; Capaccioni, F.; Giardino, M.; Cerroni, P.; Palomba, E.; Piccioni, G.

2013-09-01

The Ma_Miss (Mars Multispectral Imager for Subsurface Studies) instrument onboard of ExoMars 2018 mission to Mars will investigate the Martian subsoil down to a depth of 2 meters [1]. Ma_Miss is a miniaturized spectrometer, completely integrated within the drilling system of the ExoMars Pasteur rover; it will acquire spectra in the range 0.4-2.2μm, from the excavated borehole wall. The spectroscopic investigation of the subsurface materials will give us precious information about mineralogical, petrologic and geological processes, and will give insights about materials that have not been modified by surface processes such as erosion, weathering or oxidation. Spectroscopic measurements have been performed on Terrestrial Mars Analogues with the Ma_Miss laboratory model (breadboard). Moreover spectroscopic investigation of different sets of Terrestrial Mars Analogues is being carried on with different laboratory setups, as a support for the ExoMars-Ma_Miss instrument.

Geodetic survey as a means of improving fast MASW (Multichannel Analysis Of Surface Waves) profiling in difficult terrain/land conditions

NASA Astrophysics Data System (ADS)

Matuła, Rafał; Lewińska, Paulina

2018-01-01

This paper revolves around newly designed and constructed system that can make 2D seismic measurement in natural, subsoil conditions and role of land survey in obtaining accurate results and linking them to 3D surface maps. A new type of land streamer, designed for shallow subsurface exploration is described in this paper. In land seismic data acquisition methods a vehicle tows a line of seismic cable, lying on construction called streamer. The measurements of points and shots are taken while the line is stationary, arbitrary placed on seismic profile. Exposed land streamer consists of 24 innovatory gimballed 10 Hz geophones. It eliminates the need for hand `planting' of geophones, reducing time and costs. With the use of current survey techniques all data obtained with this instrument are being transferred in to 2D and 3D maps. This process is becoming more automatic.

Geotechnical aspects of locating the Łagiewnicka Route on the area of the "White Seas" in Kraków

NASA Astrophysics Data System (ADS)

Zięba, Jakub; Bazarnik, Mirosława

2018-04-01

The article presents the results of field studies and laboratory tests of the subsoil of the section of the ";Łagiewnicka" route located on the area of so-called "White Seas" [1] in Kraków-Łagiewniki. The analysed samples come from the layer of anthropogenic soils being the result of the operation of the Solvay Sodium Plant in the 20th century. The results of the geotechnical and land-surveying studies served as the basis for developing a numerical model to determine the pressure on the walls of the planned tunnel and the horizontal thrust in the planned excavation. Besides, the study and test results were used to perform an analysis of the excavation's stability and to check the impact of the sheet pile on land deformations near the John Paul II Centre in Kraków.

Quantifying the dilution of the radiocesium contamination in Fukushima coastal river sediment (2011-2015)

NASA Astrophysics Data System (ADS)

Evrard, Olivier; Laceby, J. Patrick; Onda, Yuichi; Wakiyama, Yoshifumi; Jaegler, Hugo; Lefèvre, Irène

2016-10-01

Fallout from the Fukushima Dai-ichi nuclear power plant accident resulted in a 3000-km2 radioactive contamination plume. Here, we model the progressive dilution of the radiocesium contamination in 327 sediment samples from two neighboring catchments with different timing of soil decontamination. Overall, we demonstrate that there has been a ~90% decrease of the contribution of upstream contaminated soils to sediment transiting the coastal plains between 2012 (median - M - contribution of 73%, mean absolute deviation - MAD - of 27%) and 2015 (M 9%, MAD 6%). The occurrence of typhoons and the progress of decontamination in different tributaries of the Niida River resulted in temporary increases in local contamination. However, the much lower contribution of upstream contaminated soils to coastal plain sediment in November 2015 demonstrates that the source of the easily erodible, contaminated material has potentially been removed by decontamination, diluted by subsoils, or eroded and transported to the Pacific Ocean.

Examining the effect of altered redox conditions on deep soil organic matter stability

NASA Astrophysics Data System (ADS)

Gabriel, C.; Kellman, L. M.; Ziegler, S. E.

2013-12-01

Since subsoil horizons contribute significantly to terrestrial carbon (C) budgets, understanding the influence of disturbances such as forest harvesting on subsoil C stability is critical. Clearcut harvesting leads to changes in the soil physico-chemical environment, including altering redox conditions arising from changes in soil hydrology that increase soil saturation, soil temperature, and pH. These physico-chemical changes have the potential to alter the adsorption of soil organic matter (SOM) to minerals, particularly at depth where SOM is primarily associated with mineral phases. The objective of this study was to determine the effect of differing redox states (aerobic vs. anaerobic) and temperature upon SOM stability of forested soils representative of the Acadian Forest Region of Eastern North America. Composite soil samples through depth (0-10, 10-20, 20-35, and 35-50 cm) from a mature red spruce forest (110 years) were incubated under optimum (aerobic) or saturated (anaerobic) conditions for 1 or 4 months at two temperatures (5 and 15 C). Following incubation, soil leachate was analyzed for dissolved organic carbon (DOC), and UV-vis absorbance in order to determine soil C losses and its optical character. Specific UV-vis absorbance SUVA (254 nm) and spectral slope ratios were calculated in order to assess the composition of chromophoric dissolved organic matter (CDOM). Preliminary results from the 1 month incubation indicate that under anaerobic conditions, all depths released DOC with a higher SUVA than under aerobic conditions, with the largest change observed in the 0-10 cm depth increment. Soil incubated at 5 C produced leachate with significantly less DOC and with a lower absorbance compared to 15 C under both redox conditions. These results suggest that both temperature and redox state are important in determining the aromaticity of DOC released from soils. Spectral slope ratios revealed that a greater proportion of CDOM of lower molecular weight (MW) compounds were released from deep mineral podzolic soils when saturated (high SUVA, low spectral slope), while higher MW CDOM were released from shallow soil strata (low SUVA, high spectral slope). This is consistent with research that indicates plant-derived SOM and microbial products each dominate in shallow and deep mineral soils, respectively. These preliminary results suggest that alterations to the redox state of a forested podzolic soil may have the potential to alter the mobilization of SOM, its composition and associated soil carbon stores.

Deep soil dynamics of floodplain carbon in the Central Valley of California

NASA Astrophysics Data System (ADS)

Steger, Kristin; Kim, Amy T.; Viers, Joshua H.; Fiener, Peter; Smart, David R.

2017-04-01

Active floodplains can putatively store large amounts of organic carbon (SOC) in subsoils originating from catchment erosion processes with subsequent floodplain deposition. Changes in catchment land use patterns and river management to optimize agricultural use of the floodplain or to restore the floodplain back to natural systems may alter SOC stocks in these soils. Our study focussed on the assessment of SOC pools associated with alluvial floodplain soils converting from conventional arable use to restored flooding and floodplain vegetation. We evaluated depth-dependent SOC contents using 21 drillings down to 3m and 10 drillings down to 7m along a transect through a floodplain area of the lower Cosumnes River, a non-constrained tributary to the Sacramento - San Joaquin Delta in California. In general, our data underline the importance of carbon stocks in subsoils >1m, which represent up to 19 and 6% of SOC stocks at the different sampling locations accounting for drillings down to 3 and 7m, respectively. All of our sampling sites revealed a SOC-rich buried A horizon between 70 and 130cm with SOC concentrations between 11 and 17g/kg, representative of the functioning floodplain system pre-disturbance. Radiocarbon dating showed that the 14C age in the buried horizon was younger than in the overlaying soils, indicating a substantial sedimentation phase with sediments of low SOC concentrations and higher carbon age. This sedimentation phase was probably associated with the huge upstream sediment production resulting from the hydraulic gold mining at the Cosumnes River starting around 1860. Apart from larger SOC contents in the buried horizon compared to the recent topsoil, its 13C and 15N isotopic signature also differed suggesting a change in long-term input of plant organic matter as well as different fertilization regimes during the agricultural use of the area from approx. 1890 onwards. In summary, deep alluvial soils in floodplains store large amounts of SOC not yet accounted for in global models. Intensive agricultural use of these floodplains often combined with river regulation and embanking of floodplain areas may lead to a slow but continuous release of the buried SOC to the atmosphere. However, restoration of floodplains may promote the stabilization of alluvial SOC in floodplains and hence contribute to more sustainable soils.

Soil characteristics of semidesert soils along a precipitation gradient in the Negev (Israel)

NASA Astrophysics Data System (ADS)

Steckenmesser, Daniel; Drahorad, Sylvie; Felix-Henningsen, Peter

2010-05-01

The sand dunes of the north-western Negev desert (Israel) show a unique precipitation gradient on a short distance. This area is build up by the same parent material and suited to investigate the influence of changes in rainfall on soil characteristics in semi-desert ecosystems. The study site is the western extension of the Sinai sand field, the sand dunes are stabilised by biological soil crusts and perennial vegetation like Retama raetam. Along this precipitation gradient the three investigation areas Nizzana South (90mm ^a-), Nizzana 84 (130mm ^a-1) and Nizzana 69 (170mm ^a-1) are situated. At every study site two soil profiles were investigated, each under the legume Retama raetam and in the bare interspace covered by biological soil crusts. The soil samples were taken at the interdune positions at every study site. The soil sampling included the biological soil crust, the topsoil and the subsoil up to 1,5 m. The narrow sampling of 20cm wide steps allow a mapping of the distribution of nutrients, carbonates and soluble salts of in order to show the impact of perennial plants and rainfall on soil properties. Soluble salts and nutrients were measured in a 1:5 water extraction, calcium carbonate was determined according to Scheibler. The data shows a strong influence of perennial shrubs on the deposition of dust and the redistribution of nutrients compared to the bare interspace. The distribution of highly and less soluble salts below the perennial shrub proofs a shallower water infiltration than in the comparable interspace area. The interspace between the plants is covered by a biological soil crust, which also strongly influences the matter fluxes by nutrient-fixation, creation of runoff and stabilization of the soil surface. These biological soil crusts show higher amounts of elements than the subsoils. The comparison of the three areas along the rainfall gradient shows higher inputs of soluble salts with increasing precipitation due to wet deposition, while carbonate contents are negatively correlated with decreasing precipitation. This is related to a higher dust input in the southern study site, which was generated in the lime stone Negev. Higher amounts of rainfall introduce higher element leaching. Perennial plants cover the surface and reduce infiltration. Inputs into the soils through dust have to be evaluated for every location to separate between effects of deposition and rainfall.

Seismic microzoning in the metropolitan area of Port - au-Prince - complexity of the subsoil

NASA Astrophysics Data System (ADS)

Gilles, R.; Bertil, D.; Belvaux, M.; Roulle, A.; Noury, G.; Prepetit, C.; Jean-Philippe, J.

2013-12-01

The magnitude 7.3 earthquake that struck Haiti in January 12, 2010 has caused a lot of damages in surrounding areas epicenter. These damages are due to a lack of knowledge of the Haitian subsoil. To overcome this problem, the LNBTP, the BME and BRGM have agreed to implement a project of seismic microzonation of the metropolitan area of Port-au-Prince which is financed by the Fund for the reconstruction of the country. The seismic microzonation is an important tool for knowledge of seismic risk. It is based on a collection of geological, geotechnical, geophysical and measures and recognition and the campaign of numerous sites. It describes a class of specific soils with associated spectral response. The objective of the microzoning is to identify and map the homogeneous zones of lithology, topography, liquefaction and ground movements. The zoning of lithological sites effect is to identify and map areas with geological and geomechanical consistent and homogeneous seismic response; the objective is to provide, in each area, seismic movements adapted to the ground. This zoning is done in about five steps: 1- Cross-analysis of geological, geotechnical and geophysical information; 2- Such information comprise the existing data collected and the data acquired during the project; 3- Identification of homogeneous areas. 4- Definition of one or more columns of representative soils associated with each zone; 5 - Possible consolidation of area to get the final seismic zoning. 27 zones types were considered for the study of sites effects after the analysis of all geological, geotechnical and geophysical data. For example, for the formation of Delmas, there are 5 areas with soil classes ranging from D to C. Soil columns described in the metropolitan area of Port-au-Prince are processed with the CyberQuake software, which is developed at the BRGM by Modaressi et al. in 1997, to calculate their response to seismic rock solicitation. The seismic motion is determined by 4 accelerograms (2 real and 2 altered real) having a spectral response close to the spectrum of acceleration to the rock. In sum, the seismic microzoning presents a better perspective for the preparation of the plan for the prevention of seismic risk (PPRS) and for the establishment of seismic rules in the metropolitan area of Port-au-Prince.

Near surface geophysical techniques on subsoil contamination: laboratory experiments

NASA Astrophysics Data System (ADS)

Capozzoli, Luigi; Giampaolo, Valeria; Rizzo, Enzo

2016-04-01

Hydrocarbons contamination of soil and groundwater has become a serious environmental problem, because of the increasing number of accidental spills caused by human activities. The starting point of any studies is the reconstruction of the conceptual site model. To make valid predictions about the flow pathways following by hydrocarbons compound is necessary to make a correct reconstruction of their characteristics and the environment in which they move. Near-surface geophysical methods, based on the study of electrical and electromagnetic properties, are proved to be very useful in mapping spatial distribution of the organic contaminants in the subsurface. It is well known, in fact, that electrical properties of the porous media are significantly influenced by hydrocarbons because, when contaminants enter the rock matrix, surface reaction occur between the contaminant and the soil grain surface. The main aim of this work is to investigate the capability of near-surface geophysical methods in mapping and monitoring spatial distribution of contaminants in a controlled setting. A laboratory experiment has been performed at the Hydrogeosite Laboratory of CNR-IMAA (Marsico Nuovo, PZ) where a box-sand has been contaminated by diesel. The used contaminant is a LNAPL, added to the sand through a drilled pipe. Contaminant behaviour and its migration paths have been monitored for one year by Electrical Resistivity measurements. In details, a Cross Borehole Electrical Resistivity Tomography techniques were used to characterize the contamination dynamics after a controlled hydrocarbon spillage occurring in the vadose zone. The approach with cross-borehole resistivity imaging provide a great advantage compared to more conventional surface electrical resistivity tomography, due to the high resolution at high depth (obviously depending on the depth of the well instrumented for the acquisition). This method has been shown to provide good information on the distribution of electrical properties of the subsoil at high depths and, in some cases, a detailed assessment of dynamic processes in the subsurface environment (Binley et al., 2002). Our study confirms the link between hydrocarbons contamination and geoelectrical signal and the capability of cross-hole electrical resistivity tomographies to realize a non-invasive characterization of LNAPL contamination of the media. Although, the electrical behaviour is much more complex and the relation with the contaminants depends also by time of investigation.

The ancient harbour system of Terracina (Latium, Italy) obtained by gravity survey.

NASA Astrophysics Data System (ADS)

di Nezza, M.; di Filippo, M.

2009-04-01

Historical research has shown that Terracina (Latina, Latium) played a fundamental role in the maritime and land traffic since before the foundation of the colony. The settlement was established where the organized system of maritime, land, coastal, and fluvial transport had the most ideal conditions to constitute an important commercial crossroads, apparently since the beginning of recorded history. In order to reconstruction the buried archaeological structures attributed to the ancient Roman port, traditionally attributed to Traiano, in the current area of the harbour of Terracina, it was carried out a gravity survey, more than 380 gravity stations. This method enables to recognize the cavity and the structures of the buildings underground through the results of variations density in the subsoil. In the residual gravity anomaly map a series of positive anomalies are visible which confirm the round structures and the pier of the buried foundations of the Imperial harbour. Unfortunately, little remains of the functioning facilities of the harbour's activities. The modern construction of the harbour, in fact, has to be developed around the new inhabitable commercial area, know today as Terracina Bassa or Borgo alla Marina. It had to be developed with a modern infrastructure of a harbor area, as in the construction of the rooms for storage of goods, warehouses, as well as for the thermal baths, hotels and amphitheatre. Furthermore, there are always the positive anomalies that characterize the area to the north-east of "Montone" hill where archaeological remains are easily visible near Via Lungolinea Pio VI. A large negative anomaly is situated in correspondence with "Montone". Gravity information shows an average density of the hill approximately 1.10 g/cm3, notably less than the recorded data relative to dry sand, approximately 1.6 g/cm3. The low value founds hits at the possibility of an "emptiness" in the subsoil of "Montone" hill, attribuiting to the possible ancient buried constructions (the rooms for storage of goods and warehouses). The sandy covering would therefore be natural from aeolian origins, like all the dunes present along this area near the southern coast of Latium. This hypothesis is in contrast to the information recorded from 1600 that attributes the formation of the reliefs accumulated to sand having been dredged up from the harbour.

Foundation integrity assessment using integrated geophysical and geotechnical techniques: case study in crystalline basement complex, southwestern Nigeria

NASA Astrophysics Data System (ADS)

Olayanju, G. M.; Mogaji, K. A.; Lim, H. S.; Ojo, T. S.

2017-06-01

The determination of parameters comprising exact depth to bedrock and its lithological type, lateral changes in lithology, and detection of fractures, cracks, or faults are essential to designing formidable foundations and assessing the integrity of civil engineering structures. In this study, soil and site characterization in a typical hard rock geologic terrain in southwestern Nigeria were carried out employing integrated geophysical and geotechnical techniques to address tragedies in civil engineering infrastructural development. The deployed geophysical measurements involved running both very low frequency electromagnetic (VLF-EM) and electrical resistivity methods (dipole-dipole imaging and vertical electrical sounding (VES) techniques) along the established traverses, while the latter technique entailed conducting geological laboratory sieve analysis and Atterberg limit-index tests upon the collected soil samples in the area. The results of the geophysical measurement, based on the interpreted VLF-EM and dipole-dipole data, revealed conductive zones and linear features interpreted as fractures/faults which endanger the foundations of public infrastructures. The delineation of four distinct geoelectric layers in the area—comprised of topsoil, lateritic/clayey substratum, weathered layer, and bedrock—were based on the VES results. Strong evidence, including high degree of decomposition and fracturing of underlying bedrock revealed by the VES results, confirmed the VLF-EM and dipole-dipole results. Furthermore, values in the range of 74.2%-77.8%, 55%-62.5%, 23.4%-24.5%, 7.7%-8.2%, 19.5%-22.4%, and 31.65%-38.25% were obtained for these geotechnical parameters viz soil percentage passing 0.075 mm sieve size, liquid limit, plasticity index, linear shrinkage, natural moisture content, and plastic limit, respectively, resulting from the geotechnical analysis of the soil samples. The comparatively analyzed geophysical and geotechnical results revealed a high weathering of charnockitic rocks resulting in plastic clay material mapped with a mean resistivity value of 73 Ohm-m, in conformity with the obtained geotechnical parameters, which failed to agree with the standard specification of subsoil foundation materials and which, in turn, can impact negatively on the foundational integrity of infrastructures. Based on these results, the area subsoils’ competence for foundation has been rated poor to low. This study has more widely demonstrated the effective application of integrative geophysical and geotechnical methods in the assessment of subsoil competence.

Assessing Protection Afforded to the Microbiological Quality of Bedrock Groundwater from the Impacts of Septic Tank Effluent by Irish Glacial Till: A Field Study

NASA Astrophysics Data System (ADS)

Orr, Alison; McCarthy, Valerie; Meehan, Robert; Flynn, Raymond

2010-05-01

The rural population of Ireland relies almost exclusively on on-site treatment systems for disposal of waste water. Septic tank systems, which discharge effluent to ground, constitute the dominant means of waste water disposal. Many of the areas that employ this technology rely on private or small group groundwater supplies, often located in close proximity of septic tanks. Since many of these water supplies provide raw groundwater to consumers, septic tank effluent (STE) can pose a significant hazard to the microbiological quality of drinking water. T-tests (infiltration testing) carried out prior to tank installation aim to assess the capacity of subsoils to receive STE. Tests completed across Ireland indicate that many existing septic tank systems are located in low permeability subsoils. These subsoils are assumed to afford significant protection to the microbiological quality of groundwater in the underlying bedrock units. A two year investigation in the Lough Muckno Catchment in Co. Monaghan, investigating the impact of STE on water quality, involved carrying out T-tests at three sites where effluent discharged to a dense, silty, ‘fractured' glacial till derived from the underlying bedrock and containing clasts of low grade metamorphic Ordovician and Silurian sandstone and shale. Analysis of groundwater samples collected from 28 piezometers straddling the water table within the till, down-gradient of septic tank systems at two sites, permitted faecal indicator microorganism (FIO) levels in near-surface groundwater to be established. Associated hydraulic conductivity tests (slug tests) at all three sites permitted an evaluation of the levels of horizontal hydraulic conductivity heterogeneity present in the till. Slug test results suggest that till median hydraulic conductivities range from 1.1x10-4 cm/s to 1.1x10-5 cm/s, with variability of up to 2 orders of magnitude across each site. On the other hand no significant differences in properties existed between sites. T-test results ranged from 37.96 min/25mm to 98.26 min/25mm, suggesting hydraulic conductivities of the order of 1.1x10-3 cm/s to 4.24x10-4 cm/s. The contrast in hydraulic conductivity between T-test and slug test results may reflect slight anisotropy within the till, with water flowing vertically a little more easily than horizontally, under equivalent gradients. Despite the low hydraulic conductivities and the low hydraulic gradients observed at each site, analyses of water samples collected from up to 115 metres from septic tank discharge points consistently detected FIOs. The results of the study highlight the possibility of viable pathogenic microorganisms being transported considerable distances from septic tanks through fine-grained glacial tills. Given limited survival times of FIOs outside of their host organisms, study findings suggest that travel times in the till separating septic tanks from monitoring points are of the order of 10s of days, despite similarly low hydraulic conductivities determined independently by the T-test and slug test methods. The microbiological results, coupled to hydraulic measurements, point to very low effective porosities in the till that may possibly relate to fracturing. Moreover, hydraulic conductivity anisotropy suggests that contaminants may flow equally easily to depth. However, the exact levels of protection provided by the till will be a function of effective porosity variation with depth; the role played by fractures remains to be investigated but could prove to be potentially significant. Overall, the results of the study suggest that the levels of protection afforded by fine-grained Irish tills to bedrock aquifers may be considerably lower than originally assumed.

Spatial-temporal variability in GHG fluxes and their functional interpretation in RusFluxNet

NASA Astrophysics Data System (ADS)

Vasenev, Ivan; Meshalkina, Julia; Sarzhanov, Dmitriy; Mazirov, Ilia; Yaroslavtsev, Alex; Komarova, Tatiana; Tikhonova, Maria

2016-04-01

High spatial and temporal variability is mutual feature for most modern boreal landscapes in the European Territory of Russia. This variability is result of their relatively young natural and land-use age with very complicated development stories. RusFluxNet includes a functionally-zonal set of representative natural, agricultural and urban ecosystems from the Central Forest Reserve in the north till the Central Chernozemic Reserve in the south (more than 1000 km distance). Especial attention has been traditionally given to their soil cover and land-use detailed variability, morphogenetic and functional dynamics. Central Forest Biosphere Reserve (360 km to North-West from Moscow) is the principal southern-taiga one in the European territory of Russia with long history of mature spruce ecosystem structure and dynamics investigation. Our studies (in frame of RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) have been concentrated on the soil carbon stocks and GHG fluxes spatial variability and dynamics due to dominated there windthrow and fallow-forest successions. In Moscow RTSAU campus gives a good possibility to develop the ecosystem and soil monitoring of GHG fluxes in the comparable sites of urban forest, field crops and lawn ecosystems taking especial attention on their meso- and micro-relief, soil cover patterns and subsoil, vegetation and land-use technologies, temperature and moisture spatial and temporal variability. In the Central Chernozemic Biosphere Reserve and adjacent areas we do the comparative analysis of GHG fluxes and balances in the virgin and mowed meadow-steppe, forest, pasture, cropland and three types of urban ecosystems with similar subsoil and relief conditions. The carried out researches have shown not only sharp (in 2-5 times) changes in GHG ecosystem and soil fluxes and balances due to seasonal and daily microclimate variation, vegetation and crop development but their essential (in 2-4 times) spatial variability due to different meso- or micro-relief forms, natural or man-made succession studies, topsoil texture or organic matter state, subsoil or perched groundwater features. Zonal, seasonal and functional subdividing the monitoring data allows essentially increase the regression links between GHG fluxes and air or soil temperature and moisture (to 0.75-0.87) that is very important for their modeling and prediction. In taiga and mix-forest zones usually there is stronger effect on GHG fluxes by air temperature than soil one due to comparatively thin (from 3 till 10 cm) layer of principal soil organic and/or humus-accumulative horizons with maximum biological activity that usually determines the total rate of GHG soil fluxes. Unfavorable seasonal conditions (dry season or low temperature) determine essential (in 1.5-2 times) decreasing not only in soil GHG fluxes but in level of their spatial variability, intraseasonal and daily dynamics too. These trends are most obvious in case of more open and sensitive to the external factors ecosystems, for example in case of industrial area lawns or at the first stages of the windthrow or fallow-forest successions. Understanding the principal regional and land-use-determined regularities of spatial and temporal changes in ecosystem and soil GHG fluxes help better modeling them in the process of spatial intra- and extrapolations, seasonal and interseasonal predictions, taking into attention basic and current principal ecological factors limiting GHG fluxes and balances. Their introduction in the ecological or agroecological models and land-use decision support systems allows improve the quality of environmental/agroecological monitoring and control not only for GHG emission but also for soil organic matter conservation, manure and nitrogen fertilizer application that is often crucially important for sustainable rural development and profitable farming.

Quantifying the dilution of the radiocesium contamination in Fukushima coastal river sediment (2011–2015)

PubMed Central

Evrard, Olivier; Laceby, J. Patrick; Onda, Yuichi; Wakiyama, Yoshifumi; Jaegler, Hugo; Lefèvre, Irène

2016-01-01

Fallout from the Fukushima Dai-ichi nuclear power plant accident resulted in a 3000-km2 radioactive contamination plume. Here, we model the progressive dilution of the radiocesium contamination in 327 sediment samples from two neighboring catchments with different timing of soil decontamination. Overall, we demonstrate that there has been a ~90% decrease of the contribution of upstream contaminated soils to sediment transiting the coastal plains between 2012 (median – M – contribution of 73%, mean absolute deviation – MAD – of 27%) and 2015 (M 9%, MAD 6%). The occurrence of typhoons and the progress of decontamination in different tributaries of the Niida River resulted in temporary increases in local contamination. However, the much lower contribution of upstream contaminated soils to coastal plain sediment in November 2015 demonstrates that the source of the easily erodible, contaminated material has potentially been removed by decontamination, diluted by subsoils, or eroded and transported to the Pacific Ocean. PMID:27694832

A field evaluation of subsurface and surface runoff. II. Runoff processes

USGS Publications Warehouse

Pilgrim, D.H.; Huff, D.D.; Steele, T.D.

1978-01-01

Combined use of radioisotope tracer, flow rate, specific conductance and suspended-sediment measurements on a large field plot near Stanford, California, has provided more detailed information on surface and subsurface storm runoff processes than would be possible from any single approach used in isolation. Although the plot was surficially uniform, the runoff processes were shown to be grossly nonuniform, both spatially over the plot, and laterally and vertically within the soil. The three types of processes that have been suggested as sources of storm runoff (Horton-type surface runoff, saturated overland flow, and rapid subsurface throughflow) all occurred on the plot. The nonuniformity of the processes supports the partial- and variable-source area concepts. Subsurface storm runoff occurred in a saturated layer above the subsoil horizon, and short travel times resulted from flow through macropores rather than the soil matrix. Consideration of these observations would be necessary for physically realistic modeling of the storm runoff process. ?? 1978.

T'ao-t'ieh, a motif of Chinese funerary art as the iconographic counterpart of Cinnabar, an alchemical drug.

PubMed

Mahdihassan, S

1982-01-01

The agency conferring resurrection is soul or its emblem. The earliest conception of soul is blood. Its Redness penetrates subsoil and is taken up by serpent, from whence arises snake-soul, later snake-god. Blood vapours is the other fraction arising upwards. It becomes wraith bird, later soul bird, and finally bird god. Blood as whole gave snake-god plus bird-god. A winged-cobra became snake-god and bird-god or together, one-as-all. Red Cock was its equivalent. As substance came cinnabar, red like blood and sublimable like soul. Dragon was idealized snake-god. Then Dragon-god plus Bird-god became the equal of blood soul, the magical power. T'ao-t'ieh is Dragon-plus-Bird, snake-god plus bird-god, the equivalent of Cosmic soul. Then cinnabar as the equal of blood soul and T'ao-t'ieh, the emblem of Cosmic soul, each were capable of conferring resurrection and have been interred in Chinese graves.

Landslides Monitoring on Salt Deposits Using Geophysical Methods, Case study - Slanic Prahova, Romania

NASA Astrophysics Data System (ADS)

Ovidiu, Avram; Rusu, Emil; Maftei, Raluca-Mihaela; Ulmeanu, Antonio; Scutelnicu, Ioan; Filipciuc, Constantina; Tudor, Elena

2017-12-01

Electrometry is most frequently applied geophysical method to examine dynamical phenomena related to the massive salt presence due to resistivity contrasts between salt, salt breccia and geological covering formations. On the vertical resistivity sections obtained with VES devices these three compartments are clearly differentiates by high resistivity for the massive salt, very low for salt breccia and variable for geological covering formations. When the land surface is inclined, shallow formations are moving gravitationally on the salt back, producing a landslide. Landslide monitoring involves repeated periodically measurements of geoelectrical profiles into a grid covering the slippery surface, in the same conditions (climate, electrodes position, instrument and measurement parameters). The purpose of monitoring landslides in Slanic Prahova area, was to detect the changes in resistivity distribution profiles to superior part of subsoil measured in 2014 and 2015. Measurement grid include several representative cross sections in susceptibility to landslides point of view. The results are graphically represented by changing the distribution of topography and resistivity differences between the two sets of geophysical measurements.

spMC: an R-package for 3D lithological reconstructions based on spatial Markov chains

NASA Astrophysics Data System (ADS)

Sartore, Luca; Fabbri, Paolo; Gaetan, Carlo

2016-09-01

The paper presents the spatial Markov Chains (spMC) R-package and a case study of subsoil simulation/prediction located in a plain site of Northeastern Italy. spMC is a quite complete collection of advanced methods for data inspection, besides spMC implements Markov Chain models to estimate experimental transition probabilities of categorical lithological data. Furthermore, simulation methods based on most known prediction methods (as indicator Kriging and CoKriging) were implemented in spMC package. Moreover, other more advanced methods are available for simulations, e.g. path methods and Bayesian procedures, that exploit the maximum entropy. Since the spMC package was developed for intensive geostatistical computations, part of the code is implemented for parallel computations via the OpenMP constructs. A final analysis of this computational efficiency compares the simulation/prediction algorithms by using different numbers of CPU cores, and considering the example data set of the case study included in the package.

The oasis of Tiout in the southwest of Algeria: Water resources and sustainable development

NASA Astrophysics Data System (ADS)

Hadidi, Abdelkader; Remini, Boualem; Habi, Mohamed; Saba, Djamel; Benmedjaed, Milloud

2016-07-01

The Tiout oasis is located in the municipality of Naama at the south west of Algeria is known by their ksour, the palm plantations and the good quality of their fruit and vegetables, in particular the dates and its varieties. This area contains enormous capacities of subsoil and superficial water. For several centuries, domestic consumption and the irrigation are carried out by the use of the traditional techniques of water collecting such as; the pendulum wells and foggaras them. Currently, this hydraulic heritage encounters technical and social problems, in particular with the contribution of drillings and the motor- pumps. The main issues are quoted: • Beating and draining of the water sources; • Degradation and abandonment of the traditional techniques.This study objective is to make an inventory of all the water sources in the study area, to study the impact of the modern technologies contribution on the ancestral techniques and finally to propose recommendations for the backup of the hydraulic heritage.

Large-scale sequestration of atmospheric carbon via plant roots in natural and agricultural ecosystems: why and how.

PubMed

Kell, Douglas B

2012-06-05

The soil holds twice as much carbon as does the atmosphere, and most soil carbon is derived from recent photosynthesis that takes carbon into root structures and further into below-ground storage via exudates therefrom. Nonetheless, many natural and most agricultural crops have roots that extend only to about 1 m below ground. What determines the lifetime of below-ground C in various forms is not well understood, and understanding these processes is therefore key to optimising them for enhanced C sequestration. Most soils (and especially subsoils) are very far from being saturated with organic carbon, and calculations show that the amounts of C that might further be sequestered (http://dbkgroup.org/carbonsequestration/rootsystem.html) are actually very great. Breeding crops with desirable below-ground C sequestration traits, and exploiting attendant agronomic practices optimised for individual species in their relevant environments, are therefore important goals. These bring additional benefits related to improvements in soil structure and in the usage of other nutrients and water.

Preliminary results of a multidisciplinary geophysical investigation in an archaeological area near Rome, with remains of a vast imperial age Roman villa

NASA Astrophysics Data System (ADS)

Florindo, F.; Sapia, V.; Marchetti, M.

2017-12-01

We present preliminary results of a multidisciplinary geophysical investigation applied to the subsoil imaging of the archaeological site of Cocciano, near Rome. The area was place of a series of archaeological findings, which are generally recognized as the remains of a vast Roman villa of the imperial age, notably attributed to Emperor Tiberius. We acquired capacitive coupled resistivity data along two parallel profiles and we performed a magnetic survey over a small subset of the survey area. The recovered resistivity models suggest the presence of a shallow, sub-horizontal, resistive layer (ρ > 350 Ωm), of slightly variable thickness (2 - 3 m), which we interpret as the response of ancient substructions overlying a relatively low-resistive layer, which we ascribe to the geological substratum. Processed magnetic data show a clear magnetic signature aligned to form a curve-shaped anomaly right at the prosecution of a nearby, partially exposed, ancient wall.

GPR Investigations in the Port of Erythrai (İzmir) Archaeological Site

NASA Astrophysics Data System (ADS)

Timur, Emre; Sarı, Coşkun; Erhan, Zülfikar; Gül Akalın Orbay, Ayşe

2016-04-01

Archaeology and the cultural heritage field can greatly benefit from reliable and non-destructive geophysical methods to map areas and structures present in the subsoil without the need for excavation. The GPR method provides coherent and interpretable images of the subsurface structures due to good signal penetration. Erythrai archaeological site is located in Çeşme district of city of İzmir (Turkey). The site has been excavated since 1960's and a great demand appeared nowadays for exploring unexcavated parts, according to improving touristic potential. Ground Penetrating Radar (GPR) measurements were carried out at the ancient port of the site. Study area was splitted into 4 parts and data were collected along 130 profiles with a profile interval of 1 m and varying lengths between 20 and 30 m. Data were interpreted and presented as 2-D vertical radargrams, horizontal time slices and 3-D models. As a result, possible ruins of shipment or fisherman shelters were determined and excavation areas were recommended.

Sub-soil contamination due to oil spills in zones surrounding oil pipeline-pump stations and oil pipeline right-of-ways in Southwest-Mexico.

PubMed

Iturbe, Rosario; Flores, Carlos; Castro, Alejandrina; Torres, Luis G

2007-10-01

Oil spills due to oil pipelines is a very frequent problem in Mexico. Petroleos Mexicanos (PEMEX), very concerned with the environmental agenda, has been developing inspection and correction plans for zones around oil pipelines pumping stations and pipeline right-of-way. These stations are located at regular intervals of kilometres along the pipelines. In this study, two sections of an oil pipeline and two pipeline pumping stations zones are characterized in terms of the presence of Total Petroleum Hydrocarbons (TPHs) and Polycyclic Aromatic Hydrocarbons (PAHs). The study comprehends sampling of the areas, delimitation of contamination in the vertical and horizontal extension, analysis of the sampled soils regarding TPHs content and, in some cases, the 16 PAHs considered as priority by USEPA, calculation of areas and volumes contaminated (according to Mexican legislation, specifically NOM-EM-138-ECOL-2002) and, finally, a proposal for the best remediation techniques suitable for the contamination levels and the localization of contaminants.

Land Resource Management as the Ground for Mining Area Sustainable Development

NASA Astrophysics Data System (ADS)

Solovitskiy, Aleksander; Brel, Olga; Nikulin, Nikolai; Nastavko, Ekaterina; Meser, Tatayna

2017-11-01

It is established that the problem of sustainable development of Kuzbass cities is their being tied to a single production and income from other sources is not considered. Therefore, their economy is underdeveloped, depends entirely on one city-forming enterprise (singleindustry city), which causes response to the slightest changes in the economic situation. In Kuzbass, all cities, except Kemerovo, are monodependent, including Kiselevsk, which economy mainly consists of coal mining enterprises. In the circumstances, there is a need to develop a set of measures for management the urban land, primarily aimed at ensuring the sustainable development of Kiselevsk city. The development of principles and management mechanism of the urban territory land fund determines its effectiveness. Establishing the dependence of rational use of land resources and sustainable development characterizes a new level of information interaction between sciences (land management and economy). Practical use of this theory is to overcome the mono-urban development of mining cities, taking into account effective subsoil management.

Intra- and inter-population polymorphism in Coletinia maggii (Grassi, 1887) (Zygentoma: Nicoletiidae), an inhabitant of soil, mesovoid shallow substratum (MSS) and caves--A challenge for the strict classification of subterranean fauna?

PubMed

Gilgado, José D; Ortuño, Vicente M

2015-02-19

New locations of Coletinia maggii (Grassi, 1887) have been discovered in the center of the Iberian Peninsula in different types of subterranean environments, such as a stony layer in the subsoil of an alluvial plain, an alluvial Mesovoid Shallow Substratum or Milieu Souterrain Superficiel (MSS) and a gypsum cave. This is the first record of both an alluvial MSS in the center of the Iberian Peninsula and of a subterranean species living in it. The high number of specimens captured allowed the first detailed study of the morphological intra- and inter-population variations of this species. The implications of its presence in these different environments, its wide distribution area across Europe, and the relevance of the morphological variation in the characters for the taxonomy of this species are discussed. Based on the results, Coletinia hernandoi Molero, Bach & Gaju, 2013 is proposed as a new synonym of C. maggii.

Visualizing Soil Landscapes on Mobile Devices

NASA Astrophysics Data System (ADS)

Schulze, Darrell; Lindbo, David

2016-04-01

The Integrating Spatial Educational Experiences (Isee) project utilizes the most detailed US soil survey data to create thematic maps of soil properties that are then combined with a highly optimized hillshade basemap for display. The Isee app, currently available for the iPad platform from the Apple App Store, allows the cached maps to be zoomed and panned quickly to any location down to a scale of 1:18,000. Maps currently available for the states of Indiana, Illinois, Kentucky, Ohio, Texas, West Virginia, and Wisconsin include, Dominant Soil Parent Materials, Natural Soil Drainage Classes, Limiting Layers, Surface Soil Colors, and Acid Subsoils. Other thematic maps will be added in the future. The ability to zoom, pan, and change maps quickly allows the user to see and understand soil landscape relationships that are not often apparent using static maps, while the ability to access the maps conveniently in the field allows the user to see how soil landscape features on the maps appear in the field.

VNIR spectroscopy of Mars Analogues with the ExoMars-Ma_Miss instrument .

NASA Astrophysics Data System (ADS)

De Angelis, S.; De Sanctis, M. C.; Ammannito, E.; Di Iorio, T.; Carli, C.; Frigeri, A.; Capria, M. T.; Federico, C.; Boccaccini, A.; Capaccioni, F.; Giardino, M.; Cerroni, P.; Palomba, E.; Piccioni, G.

The ExoMars 2018 mission will investigate the Martian surface environment with the aim of searching for eventual present or past signs of life, and to obtain a characterization of Martian soil and subsoil. The investigation of the near-surface environment and of the shallow subsurface with complementary techniques, will provide insights on the chemical and mineralogical composition, material grain size, the litotypes, the stratigraphy: these information will help us to understand the geologic processes that characterized the history of the Martian crust. The Ma_Miss (Mars Multispectral Imager for Subsurface Studies) instrument \\citep{coradini01} is a miniaturized visible and near-infrared spectrometer, integrated in the ExoMars Pasteur Rover Drill: it will acquire spectra of the borehole wall performed by the Drill, down to a depth up to two meters. Spectroscopic tests have been performed with the laboratory model (breadboard) on spectral targets and rock samples; furtherly, an activity of VNIR reflectance spectroscopy of Mars analogues has been begun with the breadboard to build a spectral library.

Study of Shallow Low-Enthalpy Geothermal Resources Using Integrated Geophysical Methods

NASA Astrophysics Data System (ADS)

De Giorgi, Lara; Leucci, Giovanni

2015-02-01

The paper is focused on low enthalpy geothermal exploration performed in south Italy and provides an integrated presentation of geological, hydrogeological, and geophysical surveys carried out in the area of municipality of Lecce. Geological and hydrogeological models were performed using the stratigraphical data from 51 wells. A ground-water flow (direction and velocity) model was obtained. Using the same wells data, the ground-water annual temperature was modeled. Furthermore, the ground surface temperature records from ten meteorological stations were studied. This allowed us to obtain a model related to the variations of the temperature at different depths in the subsoil. Integrated geophysical surveys were carried out in order to explore the low-enthalpy geothermal fluids and to evaluate the results of the model. Electrical resistivity tomography (ERT) and self-potential (SP) methods were used. The results obtained upon integrating the geophysical data with the models show a low-enthalpy geothermal resource constituted by a shallow ground-water system.

Mercury contamination study for flight system safety

NASA Technical Reports Server (NTRS)

Gorzynski, C. S., Jr.; Maycock, J. N.

1972-01-01

The effects and prevention of possible mercury pollution from the failure of solar electric propulsion spacecraft using mercury propellant were studied from tankage loading of post launch trajector injection. During preflight operations and initial flight mode there is little danger of mercury pollution if proper safety precautions are taken. Any spillage on the loading, mating, transportation, or launch pad areas is obvious and can be removed by vacuum cleaning soil and chemical fixing. Mercury spilled on Cape Kennedy ground soil will be chemically complexed and retained by the sandstone subsoil. A cover layer of sand or gravel on spilled mercury which has settled to the bottom of a water body adjacent to the system operation will control and eliminate the formation of toxic organic mercurials. Mercury released into the earth's atmosphere through leakage of a fireball will be diffused to low concentration levels. However, gas phase reactions of mercury with ozone could cause a local ozone depletion and result in serious ecological hazards.

Natural versus anthropogenic subsidence of Venice.

PubMed

Tosi, Luigi; Teatini, Pietro; Strozzi, Tazio

2013-09-26

We detected land displacements of Venice by Persistent Scatterer Interferometry using ERS and ENVISAT C-band and TerraSAR-X and COSMO-SkyMed X-band acquisitions over the periods 1992-2010 and 2008-2011, respectively. By reason of the larger observation period, the C-band sensors was used to quantify the long-term movements, i.e. the subsidence component primarily ascribed to natural processes. The high resolution X-band satellites reveal a high effectiveness to monitor short-time movements as those induced by human activities. Interpolation of the two datasets and removal of the C-band from the X-band map allows discriminating between the natural and anthropogenic components of the subsidence. A certain variability characterizes the natural subsidence (0.9 ± 0.7 mm/yr), mainly because of the heterogeneous nature and age of the lagoon subsoil. The 2008 displacements show that man interventions are responsible for movements ranging from -10 to 2 mm/yr. These displacements are generally local and distributed along the margins of the city islands.

Contamination of agricultural lands by polycyclic aromatic hydrocarbons (Tver region, Russia)

NASA Astrophysics Data System (ADS)

Zhidkin, Andrey; Koshovskii, Timur; Gennadiev, Alexander

2016-04-01

It is important to study sources and concentrations of polycyclic aromatic hydrocarbons (PAHs) in the agriculture soils within areas without intensive contaminations. Our studied object was soil and snow cover in the taiga zone (Tver region, Russia). A total of 52 surface (0-30 cm) and 31 subsurface (30-50 cm) soil samples, and 13 snow samples were collected in 35 soil pits, located in forest, crop and layland soils. Studied concentrations of the following 11 individual compounds: two-ring compounds (diphenyl and naphthalene homologues); three-ring compounds (fluorene, phenanthrene, anthracene); four-ring compounds (chrysene, pyrene, tetraphene); five-ring compounds (perylene, benzo[a]pyrene); and six-ring compounds (benzo[ghi]perylene). Analyses made by specrtofluorometry method at the temperature of liquid nitrogen. The total concentrations of all PAHs in soil samples ranged from 9 to 770 ng*g-1 with a median of 96 ng*g-1. The sum of high molecular weight PAHs was significantly lower than the sum of low molecular weight PAHs in the studied soils. The phenanthrene concentration was highest and ranged from 1.2 to 720 ng*g-1 (medium 72 ng*g-1). Compared PAHs reserves in snow cover (μg*m-2) with the reserves in topsoil layer (μg*m-2 in the upper 30 cm). Low molecular weight PAHs (fluorene, phenanthrene, diphenyl, naphthalene) reserves in snow was less than 20% from the reserves in the soil surface layer. High molecular weight PAHs (benzo[a]pyrene, chrysene, perylene, pyrene and tetraphene) reserves in snow was about 50-70% from the reserves in soil surface layer. High molecular weight PAHs (benzo[ghi]perylene and anthracene) reserves in snow was more than in topsoil. PAHs vertical distribution in soil profiles was statistically examined. The total concentration of all PAHs decreased with depth in all studied forest soils. In the arable soils was no significant trend in domination of PAHs total concentrations in the plowing and subsoil layers. The ratio of topsoil to subsoil concentrations of PAHs is different for differ congeners. Contents of phenanthrene and fluorene predominantly increase with the depth. Content of high molecular weight PAHs (benzo[a]pyrene, anthracene, tetraphene, perylene and pyrene) predominantly decreased with the depth. Other PAHs congeners have indistinct profile distributions in studied pits. Based on studied results PAHs divided to associations with different concentrations, sources and vertical distribution in soils: a) phenanthrene and fluorine; b) naphthalene, diphenyl; c) pyrene, benzo(a)pyrene, tetraphene, perylene, chrysene; d) anthracene and benzo(ghi)perylene. Research is funded by Russian Science Foundation (Project 14-27-00083).

Identifying soil landscape units at the district scale by numerically clustering remote and proximal sensed data

NASA Astrophysics Data System (ADS)

Zare, Ehsan; Huang, Jingyi; Triantafilis, John

2017-04-01

Identifying soil landscape units at a district scale is important as it allows for sustainable land-use management. However, given the large number of soil properties that need to be understood and mapped, cost-effective methods are required. In this study, we use a digital soil mapping (DSM) approach where remote and proximal sensed ancillary data collected across a farming district near Bourke, are numerical clustered (fuzzy k-means: FKM) to identify soil landscape units. The remote data was obtained from an air-borne gamma-ray spectrometer survey (i.e. potassium-K, uranium-U, thorium-Th and total counts-TC). Proximal sensed data was collected using an EM38 in the horizontal (EM38h) and vertical (EM38v) mode of operation. The FKM analysis (using Mahalanobis metric) of the kriged ancillary (i.e. common 100 m grid) data revealed a fuzziness exponent (phi) of 1.4 was suitable for further analysis and that k = 4 classes was smallest for the fuzziness performance index (FPI) and normalised classification entropy (NCE). Using laboratory measured physical (i.e. clay) and chemical (i.e. CEC, ECe and pH) properties we found k = 4 was minimized in terms of mean squared prediction error (i.e. 2p,C) when considering topsoil (0-0.3 m) clay (159.76), CEC (21.943), ECe (13.56) and pH (0.2296) and subsoil (0.9-1.2 m) clay (80.81), CEC (31.251) and ECe (16.66). These sigma2p,C are smaller than those calculated using the mapped soil landscape units identified using a traditional approach. Nevertheless, class 4A represents the Aeolian soil landscape (i.e. Nb4), while 4D, represents deep grey (CC19) self-mulching clays, and 4B and 4C yellow-grey (II1) self-mulching clays adjacent to the river and clay alluvial plain, respectively. The differences in clay and CEC reveal why 4B, 4C and 4D have been extensively developed for irrigated cotton production and also why the slightly less reactive 4B might be a source of deep drainage; evidenced by smaller topsoil (2.13 dS/m) and subsoil (3.76 dS/m) ECe. The research has implications for providing meaningful DSM of soil landscape units for farmers at districts scales where traditional methods are restrictive in terms of time and cost.

Rainfall characteristics associated to the triggering of fast- and slow-moving landslides - a comparison between the South French Alps and Lower Austria

NASA Astrophysics Data System (ADS)

Remaitre, Alexandre; Wallner, Stefan; Promper, Catrin; Glade, Thomas; Malet, Jean-Philippe

2013-04-01

Rainfall is worldwide a recognized trigger of landslides. Numerous studies were conducted in order to define the relationships between the precipitations and the triggering or the reactivation of landslides. Hydrological triggering of landslides can be divided in three general types: (1) development of local perched water tables in the subsoil leading to shallow slope instabilities and possible gravitational flows, (2) long-lasting rise in permanent water tables leading to more deep-seated slope instabilities, and (3) intense runoff causing channel-bed erosion and debris flows. Types (1) and (3) are usually observed during high rainfall intensities (hourly and daily rainfall) associated to heavy storms; type (2) is usually observed through increasing water content in the subsoil due to antecedent rainfalls (weekly or monthly rainfall) and/or massive snowmelt. Many investigations have been carried out to determine the amount of precipitation needed to trigger slopes failures. For rainfall-induced landslides a threshold may be define the rainfall, soil moisture or hydrological conditions that, when reached or exceeded, are likely to trigger landslides. Usually rainfall thresholds can be defined on physical process-based or conceptual models or empirical, historical and statistical bases. Nevertheless, both the large variety of landslides and to the extreme variety of climatic conditions leading to the triggering or the reactivation of a landslide lead to a regional definition of relationships between landslide occurrence and associated climatic conditions. The purpose of this case study is to analyze the relationships between the triggering of three types of landslides, debris flows, shallow landslides and deep-seated mudslides, and different patterns of rainfall in two study sites with different physiographic and climatic characteristics: the Barcelonnette basin in the South French Alps and the Waidhofen an der Ybbs area in Lower Austria. For this purpose, we exploit for the two test sites a landslide catalogue and rainfall data series to define a typology of rainfall induced-landslides for the relevant landslide types. Results from an analysis of the rainfall conditions associated to these events at different time scale (yearly, monthly, daily and hourly) show a clear distinction between these landslides. Slow-moving landslides are often associated to persistent rainstorms with low intensities during long periods causing the saturation of the soils while fast-moving landslides are usually triggered by short rainfall events with high intensities that occur in summer.

A simple model of carbon in the soil profile for agricultural soils in Northwestern Europe

NASA Astrophysics Data System (ADS)

Taghizadeh-Toosi, Arezoo; Hutchings, Nicholas J.; Vejlin, Jonas; Christensen, Bent T.; Olesen, Jørgen E.

2014-05-01

World soil carbon (C) stocks are second to those in the ocean, and represent three times as much C as currently present in the atmosphere. The amount of C in soil may play a significant role in carbon exchanges between the atmosphere and the terrestrial environment. The C-TOOL model is a three-pool linked soil organic carbon (SOC) model in well-drained mineral soils under agricultural land management to allow generalized parameterization for estimating effects of management measures at medium to long time scales for the entire soil profile (0-100 cm). C-TOOL has been developed to enable simulations of SOC turnover in soil using temperature dependent first order kinetics for describing decomposition. Compared with many other SOC models, C-TOOL applies a less complicated structure, which facilitates easier calibration, and it requires only few inputs (i.e., average monthly air temperature, soil clay content,soil carbon-to-nitrogen ratio, and C inputs to the soil from plants and other sources). C-TOOL was parameterized using SOC and radiocarbon data from selected long-term field treatments in United Kingdom, Sweden and Denmark. However, less data were available for evaluation of subsoil C (25-100 cm) from the long-term experiments applied. In Denmark a national 7×7 km grid net was established in 1986 for soil C monitoring down to 100 cm depth. The results of SOC showed a significant decline from 1997 to 2009 in the 0-50 cm soil layer. This was mainly attributed to changes in the 25-50 cm layer, where a decline in SOC was found for all soil texture types. Across the period 1986 to 2009 there was clear tendency for increasing SOC on the sandy soils and reductions on the loamy soils. This effect is linked to land use, since grasslands and dairy farms are more abundant in the western parts of Denmark, where most of the sandy soils are located. The results and the data from soil monitoring have been used to validate the C-TOOL modelling approach used for accounting of changes in SOC of Danish agricultural soils and for verification of the national inventories of SOC changes in agricultural soils. Future work will focus on further evaluating effects on subsoil C as well as improving the estimation of C inputs, particularly root C input at different soil depth. Key words: Soil organic carbon, modelling, C-TOOL, agriculture, management, grassland

Beyond the material grave: Life Cycle Impact Assessment of leaching from secondary materials in road and earth constructions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwab, Oliver; Karlsruhe Institute of Technology, Institute for Geography and Geoecology, Adenauerring 20, 76131 Karlsruhe; Bayer, Peter, E-mail: bayer@erdw.ethz.ch

Highlights: • We model environmental impacts of leaching from secondary construction material. • Industrial wastes in construction contain up to 45,000 t heavy metals per year (D). • In a scenario, 150 t are leached to the environment within 100 years after construction. • All heavy metals but As, Sb and Mo are adsorbed by 20 cm subsoil in this scenario. • Environmental impacts depend on material, pollutant, construction type, and geography. - Abstract: In industrialized countries, large amounts of mineral wastes are produced. They are re-used in various ways, particularly in road and earth constructions, substituting primary resources suchmore » as gravel. However, they may also contain pollutants, such as heavy metals, which may be leached to the groundwater. The toxic impacts of these emissions are so far often neglected within Life Cycle Assessments (LCA) of products or waste treatment services and thus, potentially large environmental impacts are currently missed. This study aims at closing this gap by assessing the ecotoxic impacts of heavy metal leaching from industrial mineral wastes in road and earth constructions. The flows of metals such as Sb, As, Pb, Cd, Cr, Cu, Mo, Ni, V and Zn originating from three typical constructions to the environment are quantified, their fate in the environment is assessed and potential ecotoxic effects evaluated. For our reference country, Germany, the industrial wastes that are applied as Granular Secondary Construction Material (GSCM) carry more than 45,000 t of diverse heavy metals per year. Depending on the material quality and construction type applied, up to 150 t of heavy metals may leach to the environment within the first 100 years after construction. Heavy metal retardation in subsoil can potentially reduce the fate to groundwater by up to 100%. One major challenge of integrating leaching from constructions into macro-scale LCA frameworks is the high variability in micro-scale technical and geographical factors, such as material qualities, construction types and soil types. In our work, we consider a broad range of parameter values in the modeling of leaching and fate. This allows distinguishing between the impacts of various road constructions, as well as sites with different soil properties. The findings of this study promote the quantitative consideration of environmental impacts of long-term leaching in Life Cycle Assessment, complementing site-specific risk assessment, for the design of waste management strategies, particularly in the construction sector.« less

Digging navigable waterways through lagoon tidal flats: which short and long-term impacts on groundwater dynamics and quality?

NASA Astrophysics Data System (ADS)

Teatini, Pietro; Isotton, Giovanni; Nardean, Stefano; Ferronato, Massimiliano; Tosi, Luigi; Da Lio, Cristina; Zaggia, Luca; Bellafiore, Debora; Zecchin, Massimo; Baradello, Luca; Corami, Fabiana; Libralato, Giovanni; Morabito, Elisa; Broglia, Riccardo; Zaghi, Stefano

2017-04-01

Coastal lagoons are highly valued ephemeral habitats that have experienced in many cases the pressure of human activities since the development of urbanisation and economic activities within or around their boundaries. One typical intervention is dredging of canals to increase the exchange of water with the sea or for navigation purposes. In order to divert the route of large cruise liners from the historic center of Venice, Italy, the Venice Port Authority has recently proposed a project for the dredging of a new 3-km long and 10-m deep navigation canal (called Marghera-Venice Canal, MVC, in the sequel) through the shallows of the Venice Lagoon. The MVC will connect the passenger terminal located in the southwestern part of the historic center to a main channel that reaches the industrial area on the western lagoon margin. Can the new MVC facilitate saltwater intrusion below the lagoon bottom? Can the release into the lagoon of the chemicals detected in the groundwater around the industrial site be favoured by the MVC excavation? Can the depression waves generated by the ship transit (known as ship-wakes) along the MVC affect the flow and contaminant exchange between the subsurface and surficial systems? A response to these questions has been provided by the use of uncoupled and coupled density-dependent groundwater flow and transport simulators. The hydrogeological modelling has been supported by an in-depth characterization of the Venice lagoon subsurface along the MVC. Geophysical surveys, laboratory analyses on groundwater and sediment samples, in-situ measurements through piezometers and pressure sensors, and the outcome of 3D hydrodynamic and computational fluid dynamic (CFD) models have been used to set-up and calibrate the subsurface multi-model approach. The modelling results can be summarized as follows: i) the MVC has a negligible effect in relation to the propagation of the tidal regime into the subsoil; ii) the depression caused by the ship transit along the MVC is responsible of a groundwater efflux from the canal bottom into the lagoon ranging up to 100 m3 per ship; iii) ship-wakes enhance the release of anthropogenic contaminants (As, Se, Cd, Hg, Pb, Cu, Cr) from the subsoil into the lagoon over few years after the canal excavation; iv) the MVC excavation cut the over-consolidated clay layer marking the Holocene-Pleistocene limit, thus favouring a localized salt contamination of the almost fresh-water aquifers located in the uppermost part of the Pleistocene series.

Soil stability characteristics of mulberry lands at hydro-fluctuation belt in the Three Gorges Reservoir area, China.

PubMed

Jiang, Ping; Shi, Dongmei; Hu, Xueqin; Huang, Xianzhi; Li, Yexin; Guo, Tianlei

2015-10-01

The hydro-fluctuation belt in the Three Gorges Reservoir area is a typical seasonal and artificial wetland system and ecologically fragile zone. Using the widely existing mulberry forest lands in the hydro-fluctuation belt as an example and the 180-m water-level forest land as a control, this paper analyzes the soil stability of mulberry forestlands at different water levels in the hydro-fluctuation belt by analyzing and comparing the changes between soil physical and mechanical properties. The results indicated that (1) water-level changes, such as rising, flooding, draining, and exposure, affect the soil structure in mulberry forestlands. The soil agglomeration statuses for the soil layers decreased from 180 > 175 > 170 > 165 m, and the soil agglomeration statuses at a depth of 0∼20 cm decreased by 43.79, 44.95, and 57.45% compared with the control. (2) The soil water stability index decreased as follows: 180 > 170 > 175 > 165 m, which only accounted for 50.00, 47.73, and 40.91% of the control. In addition, the soil water stability indexes for the topsoils at various water levels were 1.87 (180 m), 1.67 (175 m), 2.92 (170 m), and 1.86 (165 m) times greater than those of the subsoils; thus, the resistance to hydraulic dispersion and disintegration were greater in the topsoil than in the subsoil. (3) The soil aggregate stability index decreased from 180 > 165 > 170 > 175 m and by 22.75, 23.53, and 35.29% compared with the control. (4) The soil shear strengths (composed of the cohesive force C and the internal friction angle φ) of the topsoils at water levels of 175, 170, and 165 m were significantly lower than in the control, and the internal friction angles decreased by 10.52, 19.08, and 43.25% and the cohesive force decreased by 9.88, 16.36, and 27.51%, respectively. The stability of the soil structure was greatly influenced by the soil clay content, soil organic matter content, and waterlogging duration. The study results could provide scientific support for soil and water conservation in the hydro-fluctuation belt and for biological filter construction in the Three Gorges Reservoir area to control the transport of sediment and non-point source pollutants.

The land subsidence of the Venice historical center: twenty years of monitoring by SAR-based interferometry

NASA Astrophysics Data System (ADS)

Tosi, L.; Strozzi, T.; Teatini, P.

2012-12-01

The subsidence of Venice, one of the most beautiful and famous cities in the world, is well known not by reason of the magnitude of the ground movement, which amounts to less than 15 cm over the last century, but because it has seriously compromised the ground safety level of the city in relation of its small elevation above the sea. The lowering of Venice is still today a subject of debates with large rumours on press releases every time a scientific paper is published on the topic. Over the last two decades, satellites instrumented with SAR sensors provided excellent data for detecting land displacements by inteferometric processing. In particular, the accuracy achieved by Persistent Scatterer Interferometry (PSI) and the impressive number of detected measurement points have progressively reduced the use of in situ traditional measurements, i.e. leveling survey, for monitoring land displacements of Venice. In fact, the intensive urban development makes the historical center an optimal site for PSI. On the other hand, the correct interpretation of the PSI outcomes, which provide the relative movement of single churches, palaces, bridges with millimetric precision and metric spatial resolution, require a deep knowledge of the city and its subsoil due to the peculiarity of this urban area developed over the centuries within the sea. We investigate the movements of Venice by Interferometric Point Target Analysis (IPTA) over the last 20 years using SAR acquisitions of the ERS-1/2, ENVISAT, TerraSAR-X, and Cosmo-SkyMed satellites. The density of detected scatterers is one order of magnitude larger with the newest very high resolution X-band sensors from TerraSAR-X and Cosmo-SkyMed, but by reason of the larger observation period the accuracy of the mean displacement rate of the C-band ERS and ENVISAT is higher. IPTA results have been calibrated using leveling and permanent GPS stations to correct the so-called flattening problem, i.e. the slight phase tilt resulting by the inaccuracy in estimation of the orbital baseline due to the not perfect knowledge of the satellite positions. The comparison between the measurements covering the period from 1992 to 2011 confirms the substantial stability of the city in its whole, with a subsidence rate averaging 1 mm/yr. However, the PSI measurements also provide evidence of local zones and single structures that are subsiding at faster rates due to the heterogeneous nature of the of the upper Holocene lagoon subsoil, different load and foundation of the historical palaces, and restoration works along the canals.

Climate and root proximity as dominant drivers of enzyme activity and C and N isotopic signature in soil

NASA Astrophysics Data System (ADS)

Stock, Svenja; Köster, Moritz; Dippold, Michaela; Boy, Jens; Matus, Francisco; Merino, Carolina; Nájera, Francisco; Spielvogel, Sandra; Gorbushina, Anna; Kuzyakov, Yakov

2017-04-01

The Chilean ecosystems provide a unique study area to investigate biotic controls on soil organic matter (SOM) decomposition and mineral weathering depending on climate (from hyper arid to temperate humid). Microorganisms play a crucial role in the SOM decomposition, nutrient release and cycling. By means of extracellular enzymes microorganisms break down organic compounds and provide nutrients for plants. Soil moisture (abiotic factor) and root carbon (biotic factor providing easily available energy source for microorganisms), are important factors for microbial decomposition of SOM and show strong gradients along the investigated climatic gradient. A high input of root carbon increases microbial activity and enzyme production, and facilitates SOM breakdown and nutrient release The aim of this study was to determine the potential enzymatic SOM decomposition and nutrient release depending on root proximity and precipitation. C and N contents, δ13C and δ15N values, and kinetics (Vmax, Km) of six extracellular enzymes, responsible for C, N, and P cycles, were quantified in vertical (soil depth) and horizontal (from roots to bulk soil) gradients in two climatic regions: within a humid temperate forest and a semiarid open forest. The greater productivity of the temperate forest was reflected by higher C and N contents compared to the semiarid forest. Regression lines between δ13C and -[ln(%C)] showed a stronger isotopic fractionation from top- to subsoil at the semiarid open forest, indicating a faster SOM turnover compared to the humid temperate forest. This is the result of more favorable soil conditions (esp. temperature and smaller C/N ratios) in the semiarid forest. Depth trends of δ15N values indicated N limitation in both soils, though the limitation at the temperate site was stronger. The activity of enzymes degrading cellulose and hemicellulose increased with C content. Activity of enzymes involved in C, N and P cycles decreased from top- to subsoil and with distance to roots. Chitinase and acid phosphatase activities increased with increasing C contents and indicated a faster substrate turnover in soil under the temperate forest compared to the semiarid forest. In contrast, Tyrosin-aminopeptidase activities indicated a faster substrate turnover under semiarid forest than the temperate forest, and strongly increased with increasing N content. We conclude that the N availability and SOM turnover under semiarid open forest is higher than under humid temperate forest. The enzyme activities are depending on depth only indirectly and are driven mainly by soil C content, which is directly affected by root carbon input.

Accuracy of three-dimensional seismic ground response analysis in time domain using nonlinear numerical simulations

NASA Astrophysics Data System (ADS)

Liang, Fayun; Chen, Haibing; Huang, Maosong

2017-07-01

To provide appropriate uses of nonlinear ground response analysis for engineering practice, a three-dimensional soil column with a distributed mass system and a time domain numerical analysis were implemented on the OpenSees simulation platform. The standard mesh of a three-dimensional soil column was suggested to be satisfied with the specified maximum frequency. The layered soil column was divided into multiple sub-soils with a different viscous damping matrix according to the shear velocities as the soil properties were significantly different. It was necessary to use a combination of other one-dimensional or three-dimensional nonlinear seismic ground analysis programs to confirm the applicability of nonlinear seismic ground motion response analysis procedures in soft soil or for strong earthquakes. The accuracy of the three-dimensional soil column finite element method was verified by dynamic centrifuge model testing under different peak accelerations of the earthquake. As a result, nonlinear seismic ground motion response analysis procedures were improved in this study. The accuracy and efficiency of the three-dimensional seismic ground response analysis can be adapted to the requirements of engineering practice.

Ecological and Economic Prerequisites for the Extraction of Solid Minerals from the Bottom of the Arctic Seas

NASA Astrophysics Data System (ADS)

Myaskov, Alexander; Gonchar, Alexander

2017-11-01

The world ocean has huge reserves of minerals that are contained directly in the water, as well as on the surface of its bottom and in its subsoils. The deposits of solid minerals on the surface of the bottom of the World Ocean are considered the most promising for industrial extraction. The deposits of ferromanganese nodules, cobalt-manganese crusts and polymetallic sulphides are considered as an object of extracting more often than others. There are the largest deposits of ferromanganese nodules in the central and southern parts of the Pacific Ocean, in the central part of the Indian Ocean, and in the seas of the Arctic Ocean near Russia. The deposits of ferromanganese nodules are a serious alternative to deposits of manganese ore on land. However, there are many factors influencing the efficiency of the development of ferromanganese deposits, the most significant are: the content of the useful component in the ore, the depth of the bottom and the distance from the seaports. It is also necessary to take into account the possible environmental consequences of underwater mining.

Effect of Remediation Parameters on in-Air Ambient Dose Equivalent Rates When Remediating Open Sites with Radiocesium-contaminated Soil.

PubMed

Malins, Alex; Kurikami, Hiroshi; Kitamura, Akihiro; Machida, Masahiko

2016-10-01

Calculations are reported for ambient dose equivalent rates [H˙*(10)] at 1 m height above the ground surface before and after remediating radiocesium-contaminated soil at wide and open sites. The results establish how the change in H˙*(10) upon remediation depends on the initial depth distribution of radiocesium within the ground, on the size of the remediated area, and on the mass per unit area of remediated soil. The remediation strategies considered were topsoil removal (with and without recovering with a clean soil layer), interchanging a topsoil layer with a subsoil layer, and in situ mixing of the topsoil. The results show the ratio of the radiocesium components of H˙*(10) post-remediation relative to their initial values (residual dose factors). It is possible to use the residual dose factors to gauge absolute changes in H˙*(10) upon remediation. The dependency of the residual dose factors on the number of years elapsed after fallout deposition is analyzed when remediation parameters remain fixed and radiocesium undergoes typical downward migration within the soil column.

Global distribution of clay-size minerals on land surface for biogeochemical and climatological studies

PubMed Central

Ito, Akihiko; Wagai, Rota

2017-01-01

Clay-size minerals play important roles in terrestrial biogeochemistry and atmospheric physics, but their data have been only partially compiled at global scale. We present a global dataset of clay-size minerals in the topsoil and subsoil at different spatial resolutions. The data of soil clay and its mineralogical composition were gathered through a literature survey and aggregated by soil orders of the Soil Taxonomy for each of the ten groups: gibbsite, kaolinite, illite/mica, smectite, vermiculite, chlorite, iron oxide, quartz, non-crystalline, and others. Using a global soil map, a global dataset of soil clay-size mineral distribution was developed at resolutions of 2' to 2° grid cells. The data uncertainty associated with data variability and assumption was evaluated using a Monte Carlo method, and validity of the clay-size mineral distribution obtained in this study was examined by comparing with other datasets. The global soil clay data offer spatially explicit studies on terrestrial biogeochemical cycles, dust emission to the atmosphere, and other interdisciplinary earth sciences. PMID:28829435

Applicability of radon emanometry in lithologically discontinuous sites contaminated by organic chemicals.

PubMed

De Miguel, Eduardo; Barrio-Parra, Fernando; Elío, Javier; Izquierdo-Díaz, Miguel; García-González, Jerónimo Emilio; Mazadiego, Luis Felipe; Medina, Rafael

2018-06-02

The applicability of radon ( 222 Rn) measurements to delineate non-aqueous phase liquids (NAPL) contamination in subsoil is discussed at a site with lithological discontinuities through a blind test. Three alpha spectroscopy monitors were used to measure radon in soil air in a 25,000-m 2 area, following a regular sampling design with a 20-m 2 grid. Repeatability and reproducibility of the results were assessed by means of duplicate measurements in six sampling positions. Furthermore, three points not affected by oil spills were sampled to estimate radon background concentration in soil air. Data histograms, Q-Q plots, variograms, and cluster analysis allowed to recognize two data populations, associated with the possible path of a fault and a lithological discontinuity. Even though the concentration of radon in soil air was dominated by this discontinuity, the characterization of the background emanation in each lithological unit allowed to distinguish areas potentially affected by NAPL, thus justifying the application of radon emanometry as a screening technique for the delineation of NAPL plumes in sites with lithological discontinuities.

Phytoremediation trials on metal- and arsenic-contaminated pyrite wastes (Torviscosa, Italy).

PubMed

Vamerali, Teofilo; Bandiera, Marianna; Coletto, Lucia; Zanetti, Federica; Dickinson, Nicholas M; Mosca, Giuliano

2009-03-01

At a site in Udine, Italy, a 0.7m layer of As, Co, Cu, Pb and Zn contaminated wastes derived from mineral roasting for sulphur extraction had been covered with an unpolluted 0.15m layer of gravelly soil. This study investigates whether woody biomass phytoremediation is a realistic management option. Comparing ploughing and subsoiling (0.35m depth), the growth of Populus and Salix and trace element uptake were investigated in both pot and field trials. Species differences were marginal and species selection was not critical. Impaired above-ground productivity and low translocation of trace elements showed that bioavailable contaminant stripping was not feasible. The most significant finding was of coarse and fine roots proliferation in surface layers that provided a significant sink for trace elements. We conclude that phytostabilisation and effective immobilisation of metals and As could be achieved at the site by soil amelioration combined with woody species establishment. Confidence to achieve a long-term and sustainable remediation requires a more complete quantification of root dynamics and a better understanding of rhizosphere processes.

Monitoring of polycyclic aromatic hydrocarbons on agricultural lands surrounding Tehran oil refinery.

PubMed

Bayat, J; Hashemi, S H; Khoshbakht, K; Deihimfard, R; Shahbazi, A; Momeni-Vesalian, R

2015-07-01

Soil samples at two depths were collected and analyzed to determine the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), organic carbon, and soil pH. The Σ16PAHs were 0.13 to 3.92 mg kg(-1) at depth 1 and 0.21 to 50.32 mg kg(-1)at depth 2. The averages of the PAH compounds indicate that the area is contaminated with oil, and this pollution was greater at depth 2. Interpolation maps showed that the southern region, especially at depth 2, has been contaminated more by anthropogenic activity. The diagnostic ratios indicate several sources of pollution of the agricultural soil. A comparison of average PAHs and standard values revealed that higher molecular weight compounds in the topsoil (InP and BghiP) and subsoil (BaA, BkF, BaP, DBA, and BghiP) exceed standard values for farmland. The pH interpolation map for both depths showed that most of the area has alkaline soil from long-term irrigation with untreated urban wastewater.

[Effects of different tillage methods on phospholipid fatty acids and enzyme activities in calcareous cinnamon soil].

PubMed

Pei, Xue-Xia; Dang, Jian-You; Zhang, Ding-Yi; Wang, Jiao-Ai; Zhang, Jing

2014-08-01

In order to study changes of physical and chemical characteristics and microbial activities in soil under different tillage methods, effects of four tillage methods, rotary tillage (RT), subsoil tillage (ST), conventional tillage (CT) with corn straw returned to soil, and rotary tillage with no corn straw returned to soil (CK), on phospholipid fatty acids (PLFA) characteristics and hydrolase enzymes activities in calcareous cinnamon soil were investigated. The results showed that soil hydrolase enzymes activities, nutrient contents, microbial diversity varied greatly with the different tillage methods. Returning corn straw to soil increased the kinds, amount of soil total PLFAs, bacteria PLFAs and actonomycetes PLFAs, while decreased the fungi PLFAs, indicating that fungi was more adaptable than bacteria to an infertile environment. ST and CT resulted in higher amounts of total PLFAs, which were 74.7% and 53.3% higher than that of CK, indicating they were more beneficial to the growth of plants. They could also improve soil physical and chemical properties, increase alk-phosphatase, protease and urease activities, which would provide a favorable soil condition for high and stable crop yields.

Rice Field Geochemistry and Hydrology: An Explanation for Why Groundwater Irrigated Fields in Bangladesh are Net Sinks of Arsenic from Groundwater

PubMed Central

Neumann, Rebecca B.; St. Vincent, Allison P.; Roberts, Linda C.; Badruzzaman, A. Borhan M.; Ali, M. Ashraf; Harvey, Charles F.

2011-01-01

Irrigation of rice fields in Bangladesh with arsenic-contaminated groundwater transfers tens of cubic kilometers of water and thousands of tons of arsenic from aquifers to rice fields each year. Here we combine observations of infiltration patterns with measurements of porewater chemical composition from our field site in Munshiganj Bangladesh to characterize the mobility of arsenic in soils beneath rice fields. We find that very little arsenic delivered by irrigation returns to the aquifer, and that recharging water mobilizes little, if any, arsenic from rice field subsoils. Arsenic from irrigation water is deposited on surface soils and sequestered along flow paths that pass through bunds, the raised soil boundaries around fields. Additionally, timing of flow into bunds limits the transport of biologically available organic carbon from rice fields into the subsurface where it could stimulate reduction processes that mobilize arsenic from soils and sediments. Together, these results explain why groundwater irrigated rice fields act as net sinks of arsenic from groundwater. PMID:21332196

Magnetic Ghosts: Mineral Magnetic Measurements On Roman and Anglo-saxon Graves

NASA Astrophysics Data System (ADS)

Linford, N.

The location of inhumations, in the absence of ferrous grave goods, often presents a considerable challenge to archaeological geophysics given the small physical size of the features and the slight contrast between the fill of the grave and the surround- ing subsoil. Even during excavation, the identification of graves may be complicated where site conditions do not favour the preservation of human skeletal remains and often only a subtle soil stain is likely to survive. A recent initiative in the United King- dom has seen the formation of the Buried Organic Matter Decomposition Integrated with Elemental Status (BODIES) research group, to examine the decomposition of organic artefacts in ancient graves with respect to localised changes in pH, redox po- tential and nutrient status. This paper presents initial results from a limited mineral magnetic study of two grave sites in an attempt to ascertain whether the decomposi- tion of organic remains may lead to a detectable magnetic signature within the soil. Results from a series of isothermal, hysteresis and magneto-thermal experiments will be presented together with surface magnetometer and topsoil susceptibility surveys.

Design of foundations with sliding joint at areas affected with underground mining

NASA Astrophysics Data System (ADS)

Matečková, P.; Šmiřáková, M.; Maňásek, P.

2018-04-01

Underground mining always influences also landscape on surface. If there are buildings on the surface they are affected with terrain deformation which comprises terrain inclination, curvature, shift and horizontal deformation. Ostrava – Karvina region is specific with underground mining very close to densely inhabited area. About 25 years ago there were mines even in the city of Ostrava. Recommendations and rules for design of building structures at areas affected with underground mining have been therefore analysed in long term. This paper is focused on deformation action caused by terrain horizontal deformation - expansion or compression. Through the friction between foundation structure and subsoil in footing bottom the foundation structure has to resist significant normal forces. The idea of sliding joint which eliminates the friction and decreases internal forces comes from the last century. Sliding joint made of asphalt belt has been analysed at Faculty of Civil Engineering, VSB – Technical University of Ostrava in long term. The influence of vertical and horizontal load and the effect of temperature in temperature controlled room have been examined. Testing, design and utilization of sliding joint is presented.

Does long term exposure to radon gas influence the properties of polymeric waterproof materials?

NASA Astrophysics Data System (ADS)

Navratilova Rovenska, Katerina; Jiranek, Martin; Kokes, Pavel; Wasserbauer, Richard; Kacmarikova, Veronika

2014-01-01

The technical state of buildings and the quality of the indoor environment depend on the quality of the waterproofing course and on the properties of the insulating materials that are applied, in particular on their durability, long-term functional reliability and resistance to corrosive effects of the subsoil. Underground water chemistry and soil bacteria are well-known corrosive agents. Our investigations indicate that the ageing process of waterproof materials can be significantly accelerated by alpha particles emitted by radon and radon progenies which are present in soil gas. Materials commonly available on the building market, e.g. LDPE and HDPE of various densities, PVC, TPO (thermoplastic polyolefin), PP (polypropylene) and EPDM were selected for our experimental study. The preliminary results for 3-year exposure to radon gas show a decrease in tensile strength to 60%, elongation to 80% and hardness to 95% for samples based on PE. The diffusion coefficient of radon for samples based on PVC decreased to 20% of the initial value after 1-year exposure to radon and soil bacteria.

The Hydrologic Implications Of Unique Urban Soil Horizon Sequencing On The Functions Of Passive Green Infrastructure

NASA Astrophysics Data System (ADS)

Shuster, W.; Schifman, L. A.; Herrmann, D.

2017-12-01

Green infrastructure represents a broad set of site- to landscape-scale practices that can be flexibly implemented to increase sewershed retention capacity, and can thereby improve on the management of water quantity and quality. Although much green infrastructure presents as formal engineered designs, urbanized landscapes with highly-interspersed pervious surfaces (e.g., right-of-way, parks, lawns, vacant land) may offer ecosystem services as passive, infiltrative green infrastructure. Yet, infiltration and drainage processes are regulated by soil surface conditions, and then the layering of subsoil horizons, respectively. Drawing on a unique urban soil taxonomic and hydrologic dataset collected in 12 cities (each city representing a major soil order), we determined how urbanization processes altered the sequence of soil horizons (compared to pre-urbanized reference soil pedons) and modeled the hydrologic implications of these shifts in layering with an unsaturated zone code (HYDRUS2D). We found that the different layering sequences in urbanized soils render different types and extents of supporting (plant-available soil water), provisioning (productive vegetation), and regulating (runoff mitigation) ecosystem services.

Appalachian piedmont regolith: Relations of saprolite and residual soils to rock-type

USGS Publications Warehouse

Pavich, M.J.

1996-01-01

Saprolite is a major product of rock weathering on the Appalachian Piedmont from New Jersey to Alabama. On the Piedmont, it is the primary substrate from which residual soils are developed. Properties of saprolite and residual soils are highly related to their parent rocks. Studies of cores and outcrops illustrate that rock structure and mineralogy control upland regolith zonation. Saprolite develops by in situ chemical alteration of a wide variety of mafic to highly silicic rocks. Thickness of upland saprolite varies from a few meters on mafic rocks to tens of meters on silicic rocks. Saprolite thickness decreases with increasing slope and saprolite is generally thin or absent in valley bottoms. Massive residual subsoils and soils develop by physical and chemical processes that alter the upper few meters of saprolite. The fabric, texture and mineralogy of residual soils are distinctly different from underlying saprolite. The boundary between soil and saprolite is often gradual, and often a zone of low permeability. Geologic maps are useful guides to Piedmont regolith thickness and zonation. In regional design studies, geologic maps and regolith characteristics can be useful in environmental decision-making.

The sediments transport outcome from granite

NASA Astrophysics Data System (ADS)

Petre, Maria

2014-05-01

A landscape can be characterized by natural elements but also by the activity of the people. The shape of the landscape depends on the nature's type of rocks which compose the subsoil and on their physical-chemical properties. The action of the atmospheric factors and the presence of the water at the surface of the Earth can also shape or reshape a landscape and create new elements of the landscape. The rocks who are shaped by natural agents like the water are transformed into small particles or sediments. After this process, they can be transported by the rivers and deposed in different spots on the river according to the size of the sediments. For instance, the sand and the gravels do not travel on the same distances. The sand can be transported on a long distance and deposed near the oceans or seas, while the gravels are not transported to far from the source area. Once the sediments are no longer transported by the water, they are forming sedimentary deposits and. The sedimentary deposits suffer some transformations: a compaction and a cementation which will form the sedimentary rocks.

Natural versus anthropogenic subsidence of Venice

PubMed Central

Tosi, Luigi; Teatini, Pietro; Strozzi, Tazio

2013-01-01

We detected land displacements of Venice by Persistent Scatterer Interferometry using ERS and ENVISAT C-band and TerraSAR-X and COSMO-SkyMed X-band acquisitions over the periods 1992–2010 and 2008–2011, respectively. By reason of the larger observation period, the C-band sensors was used to quantify the long-term movements, i.e. the subsidence component primarily ascribed to natural processes. The high resolution X-band satellites reveal a high effectiveness to monitor short-time movements as those induced by human activities. Interpolation of the two datasets and removal of the C-band from the X-band map allows discriminating between the natural and anthropogenic components of the subsidence. A certain variability characterizes the natural subsidence (0.9 ± 0.7 mm/yr), mainly because of the heterogeneous nature and age of the lagoon subsoil. The 2008 displacements show that man interventions are responsible for movements ranging from −10 to 2 mm/yr. These displacements are generally local and distributed along the margins of the city islands. PMID:24067871

Water use sources of desert riparian Populus euphratica forests.

PubMed

Si, Jianhua; Feng, Qi; Cao, Shengkui; Yu, Tengfei; Zhao, Chunyan

2014-09-01

Desert riparian forests are the main body of natural oases in the lower reaches of inland rivers; its growth and distribution are closely related to water use sources. However, how does the desert riparian forest obtains a stable water source and which water sources it uses to effectively avoid or overcome water stress to survive? This paper describes an analysis of the water sources, using the stable oxygen isotope technique and the linear mixed model of the isotopic values and of desert riparian Populus euphratica forests growing at sites with different groundwater depths and conditions. The results showed that the main water source of Populus euphratica changes from water in a single soil layer or groundwater to deep subsoil water and groundwater as the depth of groundwater increases. This appears to be an adaptive selection to arid and water-deficient conditions and is a primary reason for the long-term survival of P. euphratica in the desert riparian forest of an extremely arid region. Water contributions from the various soil layers and from groundwater differed and the desert riparian P. euphratica forests in different habitats had dissimilar water use strategies.

The Structure of Resting Bacterial Populations in Soil and Subsoil Permafrost

NASA Astrophysics Data System (ADS)

Soina, Vera S.; Mulyukin, Andrei L.; Demkina, Elena V.; Vorobyova, Elena A.; El-Registan, Galina I.

2004-09-01

The structure of individual cells in microbial populations in situ of the Arctic and Antarctic permafrost was studied by scanning and transmission electron microscopy methods and compared with that of cyst-like resting forms generated under special conditions by the non-sporeforming bacteria Arthrobacter and Micrococcus isolated from the permafrost. Electron microscopy examination of microorganisms in situ revealed several types of bacterial cells having no signs of damage, including "dwarf" curved forms similar to nanoforms. Intact bacterial cells in situ and frozen cultures of the permafrost isolates differed from vegetative cells by thickened cell walls, the altered structure of cytoplasm, and the compact nucleoid, and were similar in these features to cyst-like resting forms of non-spore-forming "permafrost" bacterial strains of Arthrobacter and Micrococcus spp. Cyst-like cells, being resistant to adverse external factors, are regarded as being responsible for survival of the non-spore-formers under prolonged exposure to subzero temperatures and can be a target to search for living microorganisms in natural environments both on the Earth and on extraterrestrial bodies.

Successful implementation of biochar carbon sequestration in European soils requires additional benefits and close collaboration with the bioenergy sector

NASA Astrophysics Data System (ADS)

Hauggaard-Nielsen, Henrik; Müller-Stöver, Dorette; Bruun, Esben W.; Petersen, Carsten T.

2014-05-01

Biochar soil application has been proposed as a measure to mitigate climate change and on the same time improve soil fertility by increased soil carbon sequestration. However, while on tropical soils the beneficial effects of biochar application on crop growth often become immediately apparent, it has been shown to be more difficult to demonstrate these effects on the more fertile soils in temperate regions. Therefore and because of the lack of carbon credits for farmers, it is necessary to link biochar application to additional benefits, both related to agricultural as well as to bioenergy production. Thermal gasification of biomass is an efficient (95% energy efficiency) and flexible way (able to cope with many different and otherwise difficult-to-handle biomass fuels) to generate bioenergy, while producing a valuable by-product - gasification biochar, containing recalcitrant carbon and essential crop nutrients. The use of the residual char product in agricultural soils will add value to the technology as well as result in additional soil benefits such as providing plant nutrients and improving soil water-holding capacity while reducing leaching risks. From a soil column (30 x 130 cm) experiment with gasification straw biochar amendment to coarse sandy subsoil increased root density of barley at critical depths in the soil profile reducing the mechanical resistance was shown, increasing yields, and the soil's capacity to store plant available water. Incorporation of residuals from a bioenergy technology like gasification show great potentials to reduce subsoil constraints increasing yield potentials on poor soils. Another advantage currently not appropriately utilized is recovery of phosphorus (P). In a recent pot experiments char products originating from low-temperature gasification of various biofuels were evaluated for their suitability as P fertilizers. Wheat straw gasification biochar generally had a low P content but a high P plant availability. To improve the fertilizer value while keeping a high carbon content in the char, the gasification of a combination of sewage sludge and wheat straw was implemented, resulting in a char product with a promising performance as a fertilizer and soil amendment. To implement gasification-biochar as a promising soil improver on the marked, independently of potential carbon market developments and CO2 certificates, stakeholder involvement is strongly required. In a newly established project consortium Bregentved Estate (one of Europe's largest agriculture companies) and the DONG Energy company (one of the leading energy groups in Northern Europe) are in a joint effort trying to integrate the economic matrix of i) biomass needed for bioenergy, ii) profit from energy generation and iii) soil advantages gained from biochar application. Experiments are conducted with a 6MW biomass gasification demonstration plant producing straw biochar used in field plots (12 m x 250 m).

Human influence on late Holocene fluvial landscape and stratigraphy in the Mixteca Alta of Oaxaca, Mexico

NASA Astrophysics Data System (ADS)

Leigh, D. S.; Holdridge, G. H.; Kowalewski, S. A.

2011-12-01

The Mixteca Alta of south-central Mexico (state of Oaxaca) is a high-elevation plateau where population and agricultural steadily grew over the past 3000 years, but with a few significant episodes of population decline. Currently, the landscape is highly eroded and gullied in response to widespread land abandonment and diminished population attributed to the Spanish conquest during the 1500s and 1600s. Abandonment apparently resulted in neglect of prehistoric cross-drainage retaining walls, known as lama-bordos, which had been constructed throughout agricultural watersheds for millennia to retain runoff and sediment. Our research seeks to establish the earliest ages for construction of lama-bordos, which are buried by more than 10 m of alluvium in some localities; and we hope to determine if the chronology of alluvial sedimentation is related to fluctuations in population density versus climate changes or other drivers. Sampling is focused on relatively small tributary watersheds (<10 km^2) in the valley of Rio Culebra near the town of Coixlahuaca. Our general hypothesis is counter to Malthusian theory in that we posit land degradation and erosion was punctuated by episodes of population decline when there were insufficient people to maintain the lama-bordo infrastructure. Methods involve: (1) detailed stratigraphic and pedogenic description and sampling of several outcrops; (2) radiocarbon and luminescence dating of stratigraphic sections; (3) geochemical and lithological tracing of sedimentary beds to discriminate time periods of gully erosion; (4) relating the alluvial chronology to archaeological surveys that have established the occupation history of the region. Results indicate that upland gully erosion had occurred prior to widespread human occupation of the area, because >4000 cal yr BP cut-and-fill stratigraphic units commonly contain detritus from upland subsoil and underlying bedrock. We provide numerous radiocarbon dates for the oldest lama-bordos, and they suggest that initial construction predates 2500 cal yr BP, which is older than prevailing archaeological evidence has indicated. It appears the lama-bordos were constructed to trap gully-derived upland sediment to facilitate agriculture (largely maize cultivation). Geochemistry and lithology indicate excellent discrimination of upland soil-surface versus upland gully-derived subsoil detritus, so we are optimistic about correlating periods of exacerbated upland erosion with cultural periods of abandonment. This correlation of upland gully erosion and rapid bottomland sedimentation appears clear for the post-conquest abandonment period (1520s-1600s) until bottomlands also became gullied during the middle 1600s, but we await more radiocarbon dates to extend such correlations back in time to fully test our hypothesis. Our research is shedding new light on the extent to which people have manipulated and managed upland erosion and bottomland sedimentation for thousands of years in Mesoamerica.

Geo-information for sustainable urban development of Greater Dhaka City, Bangladesh

NASA Astrophysics Data System (ADS)

Günther, Andreas; Asaduzzaman, Atm; Bahls, Rebecca; Ludwig, Rüdiger; Ashraful Kamal, Mohammad; Nahar Faruqa, Nurun

2015-04-01

Greater Dhaka City (including Dhaka and five adjacent municipal areas) is one of the fastest developing urban regions in the world. Densely build-up areas in the developed metropolitan area of Dhaka City are subject to extensive restructuring as common six-storied buildings are replaced by higher and heavier constructions. Additional stories are built on existing houses, frequently exceeding the allowable bearing pressure on the subsoil as supported by the foundations. In turn, newly developing areas are projected in marshy areas modified by extensive, largely unengineered landfills. In many areas, these terrains bear unfavorable building ground conditions, and reliable geospatial information is a major prerequisite for risk-sensitive urban planning. Within a collaborative technical cooperation project between Bangladesh and Germany, BGR supports GSB in the provision of geo-information for the Capital Development authority (RAJUK). For general urban planning, RAJUK successively develops a detailed area plan (DAP) at scale 1 : 50000 for the whole Greater Dhaka City area. Geospatial information have not been considered in the present DAP. Within the project, GSB prepared a detailed geomorphologic map matching the DAP both in areal extent and scale. The geomorphological setting can be used as an important spatial proxy for the characterization of the subsurface since highly segmented, elevated terraces consisting of consolidated sandy Pliocene deposits overlain by stiff Plio-Pleistocene sediments are sharply bordered by low lying-areas. The floodplain and marsh areas are consisting of thick, mechanically weak Holocene fluvial sandy-silty sediments that are sometimes alternated by organic layers. A first expert-based engineering geological reclassification of the geomorphological map resulting in five building ground suitability classes is highly supported by the spatial analysis of extensive archive borehole information consisting of depth-continuous standard penetration test (SPT) observations, engineering geological sample analyses and lithological profiles. The database compiled within the project currently contains more than 1600 locations. The joining of the spatial geomorphological information with the borehole data allows a specific characterization of the building ground classes in terms of bearing capacities for different foundation designs, earthquake-induced subsoil liquefaction potentials and depth-to-engineering rock head considerations. First-order hazard and cost scenarios for several general types of projected settlements can already be broadly evaluated with the data presented in a small scale (DAP scale). However, detailed building ground surveys have to be performed at larger spatial scales (1 : 10000 - 1 : 5000) in areas assigned for new settlements. These involve regular spaced borehole observations, 3-D modeling of the subsurface and geophysical loggings. Within the project, specific representative pilot areas in different geomorphological settings are defined where detailed geospatial building ground investigations are conducted, providing a robust basis for sustainable urban planning related to natural and technological hazards and their associated risks.

Losses of soil organic carbon by converting tropical forest to plantations: Assessment of erosion and decomposition by new δ13C approach

NASA Astrophysics Data System (ADS)

Guillaume, Thomas; Muhammad, Damris; Kuzyakov, Yakov

2015-04-01

Indonesia lost more tropical forest than all of Brazil in 2012, mainly driven by the rubber, oil palm and timber industries. Nonetheless, the effects of converting forest to oil palm and rubber plantations on soil organic carbon (SOC) stocks remain unclear. We analyzed SOC losses after lowland rainforest conversion to oil palm, intensive rubber and extensive rubber plantations in Jambi province on Sumatra Island. We developed and applied a new δ13C based approach to assess and separate two processes: 1) erosion and 2) decomposition. Carbon contents in the Ah horizon under oil palm and rubber plantations were strongly reduced: up to 70% and 62%, respectively. The decrease was lower under extensive rubber plantations (41%). The C content in the subsoil was similar in the forest and the plantations. We therefore assumed that a shift to higher δ13C values in the subsoil of the plantations corresponds to the losses of the upper soil layer by erosion. Erosion was estimated by comparing the δ13C profiles in the undisturbed soils under forest with the disturbed soils under plantations. The estimated erosion was the strongest in oil palm (35±8 cm) and rubber (33±10 cm) plantations. The 13C enrichment of SOC used as a proxy of its turnover indicates a decrease of SOC decomposition rate in the Ah horizon under oil palm plantations after forest conversion. SOC availability, measured by microbial respiration rate and Fourier Transformed Infrared Spectroscopy, was lower under oil palm plantations. Despite similar trends in C losses and erosion in intensive plantations, our results indicate that microorganisms in oil palm plantations mineralized mainly the old C stabilized prior to conversion, whereas microorganisms under rubber plantations mineralized the fresh C from the litter, leaving the old C pool mainly untouched. Based on the lack of C input from litter, we expect further losses of SOC under oil palm plantations, which therefore are a less sustainable land-use compared to rubber plantations. Finally, we discussed the advantages and limitations of the new δ13C based approach to assess erosion and decomposition as well as possibilities for its development and broader application. The reestablishment of new oil palm plantations has just started in the studied region. We therefore advise 1) to reduce the period without soil protection by planting cover crops at the early stage of the establishment to reduce soil erosion and 2) to leave a maximum of the biomass from the old palm trees on site and/or to keep the land lying fallow for a few years to enable the reconstruction of the SOC pool for the next oil palm generation.

Potential enzyme activities in cryoturbated organic matter of arctic soils

NASA Astrophysics Data System (ADS)

Schnecker, J.; Wild, B.; Rusalimova, O.; Mikutta, R.; Guggenberger, G.; Richter, A.

2012-12-01

An estimated 581 Gt organic carbon is stored in arctic soils that are affected by cryoturbtion, more than in today's atmosphere (450 Gt). The high amount of organic carbon is, amongst other factors, due to topsoil organic matter (OM) that has been subducted by freeze-thaw processes. This cryoturbated OM is usually hundreds to thousands of years old, while the chemical composition remains largely unaltered. It has therefore been suggested, that the retarded decomposition rates cannot be explained by unfavourable abiotic conditions in deeper soil layers alone. Since decomposition of soil organic material is dependent on extracellular enzymes, we measured potential and actual extracellular enzyme activities in organic topsoil, mineral subsoil and cryoturbated material from three different tundra sites, in Zackenberg (Greenland) and Cherskii (North-East Siberia). In addition we analysed the microbial community structure by PLFAs. Hydrolytic enzyme activities, calculated on a per gram dry mass basis, were higher in organic topsoil horizons than in cryoturbated horizons, which in turn were higher than in mineral horizons. When calculated on per gram carbon basis, the activity of the carbon acquiring enzyme exoglucanase was not significantly different between cryoturbated and topsoil organic horizons in any of the three sites. Oxidative enzymes, i.e. phenoloxidase and peroxidase, responsible for degradation of complex organic substances, showed higher activities in topsoil organic and cryoturbated horizons than in mineral horizons, when calculated per gram dry mass. Specific activities (per g C) however were highest in mineral horizons. We also measured actual cellulase activities (by inhibiting microbial uptake of products and without substrate addition): calculated per g C, the activities were up to ten times as high in organic topsoil compared to cryoturbated and mineral horizons, the latter not being significantly different. The total amount of PLFAs, as a proxy for microbial biomass, was significantly higher in topsoil organic horizons than in cryoturbated and mineral horizons. Changes in the microbial community composition were mainly caused by the relative amount of fungal biomarkers. Within the fungal community the biomarker 18:2w6, which is often associated with ectomycorrhiza, was negatively correlated to the general fungal biomarker 18:1w9. This negative correlation indicates a shift from mycorrhizal to saprotrophic fungi from topsoil towards cryoturbatad and mineral subsoil horizons. In summary, the measured oxidative and hydrolytic (potential) enzyme activities cannot explain the previously observed retarded decomposition in cryoturbated horizons. The measured actual cellulase activity however was strongly reduced in cryoturbated material compared to topsoil horizons. A possible explanation for the observed strong reduction of actual cellulase activity could lie within the fungal community structure which shifted towards saprotrophic fungi from topsoil to cryoturbated horizons.

Subsoil erosion dominates the supply of fine sediment to rivers draining into Princess Charlotte Bay, Australia.

PubMed

Olley, Jon; Brooks, Andrew; Spencer, John; Pietsch, Timothy; Borombovits, Daniel

2013-10-01

The Laura-Normanby River (catchment area: 24,350 km(2)), which drains into Princess Charlotte Bay, has been identified in previous studies as the third largest contributor of sediment to the Great Barrier Reef World Heritage Area. These catchment scale modelling studies also identified surface soil erosion as supplying >80% of the sediment. Here we use activity concentrations of the fallout radionuclides (137)Cs and (210)Pbex to test the hypothesis that surface soil erosion dominates the supply of fine (<10 μm) sediment in the river systems draining into Princess Charlotte Bay. Our results contradict these previous studies, and are consistent with channel and gully erosion being the dominant source of fine sediment in this catchment. The hypothesis that surface soil erosion dominates the supply of fine sediment to Princess Charlotte Bay is rejected. River sediment samples were collected using both time-integrated samplers and sediment drape deposits. We show that there is no detectable difference in (137)Cs and (210)Pbex activity concentrations between samples collected using these two methods. Two methods were also used to collect samples to characterise (137)Cs and (210)Pbex concentrations in sediment derived from surface soil erosion; sampling of surface-wash deposits and deployment of surface runoff traps that collected samples during rain events. While there was no difference in the (137)Cs activity concentrations for samples collected using these two methods, (210)Pbex activity concentrations were significantly higher in the samples collected using the runoff traps. The higher (210)Pbex concentrations are shown to be correlated with loss-on-ignition (r(2) = 0.79) and therefore are likely to be related to higher organic concentrations in the runoff trap samples. As a result of these differences we use a three end member mixing model (channel/gully, hillslope surface-wash and hillslope runoff traps) to determine the relative contribution from surface soil erosion. Probability distributions for (137)Cs and (210)Pbex concentrations were determined for each of the end members, with these distributions then used to estimate the surface soil contribution to each of the collected river sediment samples. The mean estimate of contribution of surface derived sediment for all river samples (n = 70) is 16 ± 2%. This study reinforces the importance of testing model predictions before they are used to target investment in remedial action and adds to the body of evidence that the primary source of sediment delivered to tropical river systems is derived from subsoil erosion. Copyright © 2013 Elsevier Ltd. All rights reserved.

Experimental infrared measurements for hydrocarbon pollutant determination in subterranean waters

NASA Astrophysics Data System (ADS)

Lay-Ekuakille, A.; Palamara, I.; Caratelli, D.; Morabito, F. C.

2013-01-01

Subterranean waters are often polluted by industrial and anthropic effluents that are drained in subsoil. To prevent and control pollution, legislations of different developed countries require an online monitoring measurement, especially for detecting organic solvents (chlorinated and unchlorinated ones). Online measurements include both real-time and no real-time measurements. In general, it is difficult to implement real-time measurements in stricto sensu for online acquisitions on aqueous effluents since they need to be processed by a modeling. This research presents an experimental measurement system based on infrared (IR) spectroscopy for aqueous effluents containing hydrocarbons and capable of displaying excellent values of pollutant concentrations even in instable conditions; the system is able to detect pollutants either in laminar or turbulent flow. The results show the possibility of avoiding the use of "Pitot tube" that is employed to create a stagnation point in order to convert kinetic energy into potential one. This conversion allows the transformation of a turbulent flow in a laminar flow making easy measurement of pollutants included in an aqueous effluent. Obviously, "Pitot tube" is also used for other fluid effluents. The obtained results have been compared with those produced by means of sophisticated IR instrumentation for laboratory applications.

Experimental infrared measurements for hydrocarbon pollutant determination in subterranean waters.

PubMed

Lay-Ekuakille, A; Palamara, I; Caratelli, D; Morabito, F C

2013-01-01

Subterranean waters are often polluted by industrial and anthropic effluents that are drained in subsoil. To prevent and control pollution, legislations of different developed countries require an online monitoring measurement, especially for detecting organic solvents (chlorinated and unchlorinated ones). Online measurements include both real-time and no real-time measurements. In general, it is difficult to implement real-time measurements in stricto sensu for online acquisitions on aqueous effluents since they need to be processed by a modeling. This research presents an experimental measurement system based on infrared (IR) spectroscopy for aqueous effluents containing hydrocarbons and capable of displaying excellent values of pollutant concentrations even in instable conditions; the system is able to detect pollutants either in laminar or turbulent flow. The results show the possibility of avoiding the use of "Pitot tube" that is employed to create a stagnation point in order to convert kinetic energy into potential one. This conversion allows the transformation of a turbulent flow in a laminar flow making easy measurement of pollutants included in an aqueous effluent. Obviously, "Pitot tube" is also used for other fluid effluents. The obtained results have been compared with those produced by means of sophisticated IR instrumentation for laboratory applications.

Perfection Of Methods Of Mathematical Analysis For Increasing The Completeness Of Subsoil Development

NASA Astrophysics Data System (ADS)

Fokina, Mariya

2017-11-01

The economy of Russia is based around the mineral-raw material complex to the highest degree. The mining industry is a prioritized and important area. Given the high competitiveness of businesses in this sector, increasing the efficiency of completed work and manufactured products will become a central issue. Improvement of planning and management in this sector should be based on multivariant study and the optimization of planning decisions, the appraisal of their immediate and long-term results, taking the dynamic of economic development into account. All of this requires the use of economic mathematic models and methodsApplying an economic-mathematic model to determine optimal ore mine production capacity, we receive a figure of 4,712,000 tons. The production capacity of the Uchalinsky ore mine is 1560 thousand tons, and the Uzelginsky ore mine - 3650 thousand. Conducting a corresponding analysis of the production of OAO "Uchalinsky Gok", an optimal production plan was received: the optimal production of copper - 77961,4 rubles; the optimal production of zinc - 17975.66 rubles. The residual production volume of the two main ore mines of OAO "UGOK" is 160 million tons of ore.

[Cancer incidence and mortality among persons having been exposed to ionizing waves in a school in Val-de-Marne].

PubMed

Germonneau, P; Castor, C

2006-09-01

The Marie Curie School of Nogent-Sur-Mame (Val-de-Marne, France) was built in 1969 on the site of a former radium extracting plant. Due to remaining radioactive waste in the subsoil, school staff and students who attended the school have been exposed to radiation. A retrospective cohort study was conducted on the 3,403 persons who had attended the school regularly until it closed down in 1998. The national health insurance register was used to trace people. Incidence of cancers, leukaemia and mortality were analysed. In the population of the pupils a significant excess risk for leukaemia was observed (Standardized Incidence Ratio = 4.6 IC 95% [1.66 - 9.89]). These results are not conclusive because of the high proportion of those who could not be traced and were lost to any opportunity for follow-up (42%), and because of preferential recruitment due to a bias generated by the query of the records being centred on searching specifically for those who were sick. The difficulties met by the authors justify that when faced with similar problems in the future, greater attention should be paid to the feasibility study before any involvement or action.

Spatial distribution of enzyme driven reactions at micro-scales

NASA Astrophysics Data System (ADS)

Kandeler, Ellen; Boeddinghaus, Runa; Nassal, Dinah; Preusser, Sebastian; Marhan, Sven; Poll, Christian

2017-04-01

Studies of microbial biogeography can often provide key insights into the physiologies, environmental tolerances, and ecological strategies of soil microorganisms that dominate in natural environments. In comparison with aquatic systems, soils are particularly heterogeneous. Soil heterogeneity results from the interaction of a hierarchical series of interrelated variables that fluctuate at many different spatial and temporal scales. Whereas spatial dependence of chemical and physical soil properties is well known at scales ranging from decimetres to several hundred metres, the spatial structure of soil enzymes is less clear. Previous work has primarily focused on spatial heterogeneity at a single analytical scale using the distribution of individual cells, specific types of organisms or collective parameters such as bacterial abundance or total microbial biomass. There are fewer studies that have considered variations in community function and soil enzyme activities. This presentation will give an overview about recent studies focusing on spatial pattern of different soil enzymes in the terrestrial environment. Whereas zymography allows the visualization of enzyme pattern in the close vicinity of roots, micro-sampling strategies followed by MUF analyses clarify micro-scale pattern of enzymes associated to specific microhabitats (micro-aggregates, organo-mineral complexes, subsoil compartments).

Selective placement disposal of drilling fluids in west Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

McFarland, M.L.

1988-01-01

Burial of spent drilling fluids used in petroleum and natural gas exploration was evaluated as an alternative disposal technique for reducing surface soil contamination in western Texas. Simulated reserve pits were constructed to provide burial depths of 30, 90, and 150 cm below the surface, with orderly replacement of stockpiled subsoil and topsoil. Movement of soluble salts and heavy metals from drilling fluids into the overlying soil was monitored over a 20-month period. The effects of depth of drilling fluid burial on establishment, yields, and chemical composition of transplanted fourwing saltbush (Atriplex canescens (Pursh) Nutt.) and buffalograss (Buchloe dactyloides (Nutt.)more » Engelm.) were determined for two growing seasons. Sodium, Ca{sup +2}, and Cl{sup {minus}} were the dominant mobile ions, while migration of Mg{sup +2}, K{sup +}, and SO{sub 4}{sup {minus}2} was observed to a lesser degree. Exchangeable sodium percentages in the 15-cm zone immediately above drilling fluid ranged from 1.9 to 19.0 after 20 months. Total concentrations of Ba, Cr, Cu, Ni, and Zn were greater in drilling fluids than in native soil, but there was no evidence of migration of these metals into overlying soil.« less

Vertical nutrient and trace element migration in cambisoils after application of residues from anaerobic digestion of pig manure

NASA Astrophysics Data System (ADS)

Sager, Manfred; Unterfrauner, Hans

2013-04-01

Cambisols sampled in alpine pastures were packed into soil columns in order to monitor downward migration of nutrient and trace elements, applied within the residue from anaerobic digestion of a pig manure. 2 rain events per week were simulated. The manure added substantial amounts of K, ammonium, Na, Ca, P, S, Cl, B, Zn and Cu to the soil, whereas Mg, Mn, Ni, Cr, Pb, Cd and V were at the same level. In the eluates, total elemental composition as well as nitrate and ammonium were monitored. Addition of soluble Fe (at 1000 mg/l as FeCl3) decreased the release of soluble sulphate, but had no significant effect on the release of Fe and P. During subsequent rain events, exchangeable K remained enriched in the topsoil, wheras total sulfur moved to deeper layers. After 8 weeks, the columns were dismantled and analyzed for quasi-total and mobile fractions. Both in topsoils and subsoils, manure addition finally increased soil pH in case of low P soils, but decreased soil pH in case of high pH soils. Effects of manure applications on groundwater formation processes will be discussed.

Linking groundwater pollution to the decay of 15th-century sculptures in Burgos Cathedral (northern Spain).

PubMed

Gázquez, Fernando; Rull, Fernando; Medina, Jesús; Sanz-Arranz, Aurelio; Sanz, Carlos

2015-10-01

Precipitation of salts-mainly hydrated Mg-Na sulfates-in building materials is rated as one of the most severe threats to the preservation of our architectural and cultural heritage. Nevertheless, the origin of this pathology is still unknown in many cases. Proper identification of the cause of damage is crucial for correct planning of future restoration actions. The goal of this study is to identify the source of the degradation compounds that are affecting the 15th-century limestone sculptures that decorate the retro-choir of Burgos Cathedral (northern Spain). To this end, detailed characterization of minerals by in situ (Raman spectroscopy) and laboratory techniques (XRD, Raman and FTIR) was followed by major elements (ICP and IC) and isotopic analysis (δ(34)S and δ(15)N) of both the mineral phases precipitated on the retro-choir and the dissolved salts in groundwater in the vicinity of the cathedral. The results reveal unequivocal connection between the damage observed and capillary rise of salts-bearing water from the subsoil. The multianalytical methodology used is widely applicable to identify the origin of common affections suffered by historical buildings and masterpieces.

Studies on geotechnical properties of subsoil in south east coastal region of India

NASA Astrophysics Data System (ADS)

Dutta, Susom; Barik, D. K.

2017-11-01

Soil testing and analysis has become essential before commencement of any activity or process on soil i.e. residential construction, road construction etc. It is the most important work particularly in coastal area as these areas are more vulnerable to the natural disastrous like tsunami and cyclone. In India, there is lack of facility to collect and analyse the soil from the field. Hence, to study the various characteristics of the coastal region sub soil, Old Mahabalipuram area, which is the South East region of India has been chosen in this study. The aim of this study is to collect and analyse the soil sample from various localities of the Old Mahabalipuram area. The analysed soil data will be helpful for the people who are working in the field of Geotechnical in coastal region of India to make decision. The soil sample collected from different boreholes have undergone various field and laboratory tests like Pressuremeter Test, Field Permeability Test, Electrical Resistivity Test, Standard Penetration Test, Shear Test, Atterberg Limits etc. are performed including rock tests to know the geotechnical properties of the soil samples for each and every stratum

Epidemiological investigations into multiple sclerosis in southern Hesse. II. The distribution of cases in relation to exogenous features.

PubMed

Lauer, K; Firnhaber, W

1984-10-01

In order to discover possible exogenous variables associated with a higher multiple sclerosis risk, the distribution of cases with definite and probable multiple sclerosis ascertained in the course of a micro-epidemiologic study in Southern Hesse was evaluated and compared with some environmental factors. The prevalence in 1980, the prevalence of cases with disease-onset within the region according to locality of onset and the rate of native Southern Hesse patients according to childhood residence all showed a similar geographical distribution, with the highest values in the south-eastern, mountainous part of the region. This district has a lower annual mean temperature, more annual snow-days and a higher annual precipitation compared to the remaining area. A statistical comparison revealed no association with industrial or agricultural activities, with a particular type of land use, with cattle, pig- or horse-breeding, or with sanitary or housing standards. On the other hand, a slight association with the soil type could be demonstrated, with higher rates on loam and clay subsoils when compared to predominantly sandy regions. Whether this finding has any significance or not remains to be clarified.

The hydrogeology of the military inundation at the 1914-1918 Yser front (Belgium)

NASA Astrophysics Data System (ADS)

Vandenbohede, Alexander

2016-03-01

Protection against flooding by the sea, drainage of rainwater and integrated management of groundwater and surface-water resources are key issues in low-lying coastal areas. However, under exceptional circumstances, knowledge to keep coastal areas dry and habitable can be used otherwise. Inundation for military purposes is such an example. The hydrogeology of the inundation at the Yser River, Belgium, during the Great War is studied. The inundation started in October 1914 to stop the German advance and lasted until 1918. A water balance and groundwater model are combined to derive the water balance before and during the inundation and to study the impact on the groundwater system. It is concluded that a number of hydrogeological factors contributed to the effectiveness of the inundation. Most importantly, the low-permeability subsoil facilitated loss of inundation water mainly by evaporation. Further, the normal water management strategy of the area (aimed at evacuating excess water towards the sea) was reversed to keep water between the opposing armies. However, the duration of the inundation meant a reorganization of the drainage of areas not inundated; truly an exercise in integrated water management.

GPR detectability of rocks in a Martian-like shallow subsoil: A numerical approach

NASA Astrophysics Data System (ADS)

Valerio, Guido; Galli, Alessandro; Matteo Barone, Pier; Lauro, Sebastian E.; Mattei, Elisabetta; Pettinelli, Elena

2012-03-01

In this work, the ability of Ground Penetrating Radar (GPR) to detect rocks buried in composite soil is studied in connection with the planned ExoMars mission, as GPR will be used during this mission to scan the Martian subsurface to help define feasible sites for shallow drilling. A realistic model of the operating environment is implemented through a full-wave electromagnetic simulator, taking into account the antenna system and the signal features. The flexibility and efficiency of this numerical approach has allowed for the analysis of a great variety of configurations. The regolith is modeled based on data from recent explorations, while various kinds of embedded rocks are considered that have different geometrical and physical characteristics. The simulated results are compared with ad hoc GPR measurements performed on basalts buried in a mixture of glass beads, as an analogue of a dry sandy Martian soil. A very good agreement between theoretical and experimental results is found, thus validating the proposed numerical approach. This research has defined useful and reliable information concerning the prediction of scattering effects from buried objects in the environment where the ExoMars rover will operate.

Lateral weathering gradients in glaciated catchments

NASA Astrophysics Data System (ADS)

McGuire, K. J.; Bailey, S. W.; Ross, D. S.; Strahm, B. D.; Schreiber, M. E.

2016-12-01

Mineral dissolution and the distribution of weathering products are fundamental processes that drive development and habitability of the Earth's critical zone; yet, the spatial configuration of these processes in some systems is not well understood. Feedbacks between hydrologic flows and weathering fluxes are necessary to understanding how the critical zone develops. In upland glaciated catchments of the northeastern USA, primary mineral dissolution and the distribution of weathering products are spatially distinct and predictable over short distances. Hillslopes, where shallow soils force lateral hydrologic fluxes through accumulated organic matter, produce downslope gradients in mineral depletion, weathering product accumulation, soil development, and solute chemistry. We propose that linked gradients in hydrologic flow paths, soil depth, and vegetation lead to predictable differences in the location and extent of mineral dissolution in regolith (soil, subsoil, and rock fragments) and bedrock, and that headwater catchments within the upland glaciated northeast show a common architecture across hillslopes as a result. Examples of these patterns and processes will be illustrated using observations from the Hubbard Brook Experimental Forest in New Hampshire where laterally distinct soils with strong morphological and biogeochemical gradients have been documented. Patterns in mineral depletion and product accumulation are essential in predicting how ecosystems will respond to stresses, disturbance, and management.

Sorption of lambda-cyhalothrin, cypermethrin, deltamethrin and fenvalerate to quartz, corundum, kaolinite and montmorillonite.

PubMed

Oudou, H Chaaieri; Hansen, H C Bruun

2002-12-01

Sorption to mineral surfaces may be important for retention and degradation of hydrophobic pesticides in subsoils and aquifers poor in organic matter. In this work the title pyrethroids have been used to investigate selective interactions with the surfaces of four minerals. Sorption of the four pyrethroids was quantified in batch experiments with initial pyrethroid concentrations of 1-100 microg/l. Sorption to centrifuge tubes used in the batch experiments accounted for 25-60% of total sorption. Net sorption was obtained from total sorption after subtracting the amounts of pyrethroids sorbed to centrifuge tubes used. All isotherms could be fitted by the Freundlich equation with n ranging between 0.9 and 1.1. Bonding affinities per unit surface area decreased in the order: corundum > quartz > montmorillonite approximately equal kaolinite. A similar sequence as found for the total surface tension of the minerals. All minerals showed the same selectivity order with respect to sorption affinity of the four pyrethroids: lambda-cyhalothrin > deltamethrin > cypermethrin > fenvalerate, which shows that the most hydrophobic compound is sorbed most strongly. Stereochemical properties of the four pyrethroid formulations may also contribute to the selectivity pattern.

Amino acid production exceeds plant nitrogen demand in Siberian tundra

NASA Astrophysics Data System (ADS)

Wild, Birgit; Eloy Alves, Ricardo J.; Bárta, Jiři; Čapek, Petr; Gentsch, Norman; Guggenberger, Georg; Hugelius, Gustaf; Knoltsch, Anna; Kuhry, Peter; Lashchinskiy, Nikolay; Mikutta, Robert; Palmtag, Juri; Prommer, Judith; Schnecker, Jörg; Shibistova, Olga; Takriti, Mounir; Urich, Tim; Richter, Andreas

2018-03-01

Arctic plant productivity is often limited by low soil N availability. This has been attributed to slow breakdown of N-containing polymers in litter and soil organic matter (SOM) into smaller, available units, and to shallow plant rooting constrained by permafrost and high soil moisture. Using 15N pool dilution assays, we here quantified gross amino acid and ammonium production rates in 97 active layer samples from four sites across the Siberian Arctic. We found that amino acid production in organic layers alone exceeded literature-based estimates of maximum plant N uptake 17-fold and therefore reject the hypothesis that arctic plant N limitation results from slow SOM breakdown. High microbial N use efficiency in organic layers rather suggests strong competition of microorganisms and plants in the dominant rooting zone. Deeper horizons showed lower amino acid production rates per volume, but also lower microbial N use efficiency. Permafrost thaw together with soil drainage might facilitate deeper plant rooting and uptake of previously inaccessible subsoil N, and thereby promote plant productivity in arctic ecosystems. We conclude that changes in microbial decomposer activity, microbial N utilization and plant root density with soil depth interactively control N availability for plants in the Arctic.

Geochemical mapping of radioactive elements using helicopter-borne gamma-ray spectrometry (Tiouit, Eastern Anti-Atlas, Morocco): Or occurrence and environmental impact

NASA Astrophysics Data System (ADS)

Miftah, Abdelhalim; El Azzab, Driss; Attou, Ahmed; Manar, Ahmed; Rachid, Ahmed; Ramhy, Haytam

2018-03-01

The spectrometric prospection is a direct geophysical method based on the analysis of the radioactive elements spectra, due to three principal radioactive elements 40K, 238U and 232Th. In order to measure the content of radioactive elements a geophysical helicopter survey was carried out to a flight altitude of 60 m from the subsoil, covering the geological map of Tiouit 1/50,000 with an extent of 45.5 × 29 km2. In this paper, we propose an application in the environment and or occurrence by the production of maps concentration in K, U and Th to delimit the areas with purely natural radioactive risk by the calculation of the dose rate in mSv, the found values show a variation of 0,3 with 1649 mSv with a median value of 0,831 mSv. Moreover, data processing as the horizontal gradient filter which allowed to amplify the spectrometric signatures, this one coupled to the upward continuation, lead us to a better location of the abrupt changes, which materialize by spectrometric lineaments, reflecting the change of the geochemical properties of the basement.

Subsoil TPH contamination in two oil pipeline pumping stations and one pipeline right-of-way in north Mexico.

PubMed

Iturbe, R; Flores-Serrano, R M; Castro, A; Flores, C; Torres, L G

2010-11-01

This investigation deals with the characterization carried out in zones around two pipeline pumping stations and one pipeline right-of-way in the north of Mexico. In particular those areas where contamination was evaluated: (a) south area of the separation ditch in the Avalos station, (b) the area between the separation ditch at the Avalos station, (c) km 194+420 of the Moctuzma station, and (d) km 286+900 in the Candelaria station. Results of this investigation showed that only four samples showed TPH values higher than the Mexican limit for 2004: AVA 1B, with 21,191 mg kg(-1); AVA 1C, with 9348 mg kg(-1); AVA 2B, with 13,970 mg kg(-1); and MOC 2A, with 4108 mg kg(-1).None of the sampled points showed the presence of PAHs at values higher than those found in the Mexican or American legislations. PAH were detected in the range of 0.0004 and 13.05 mg kg(-1).It is suggested to implement surfactant soil washing as a remediation technique for the approximately 600 m(3) that need to be treated. Copyright 2010 Elsevier Ltd. All rights reserved.

Wireless acquisition of multi-channel seismic data using the Seismobile system

NASA Astrophysics Data System (ADS)

Isakow, Zbigniew

2017-11-01

This paper describes the wireless acquisition of multi-channel seismic data using a specialized mobile system, Seismobile, designed for subsoil diagnostics for transportation routes. The paper presents examples of multi-channel seismic records obtained during system tests in a configuration with 96 channels (4 landstreamers of 24-channel) and various seismic sources. Seismic waves were generated at the same point using different sources: a 5-kg hammer, a Gisco's source with a 90-kg pile-driver, and two other the pile-drivers of 45 and 70 kg. Particular attention is paid to the synchronization of source timing, the measurement of geometry by autonomous GPS systems, and the repeatability of triggering measurements constrained by an accelerometer identifying the seismic waveform. The tests were designed to the registration, reliability, and range of the wireless transmission of survey signals. The effectiveness of the automatic numbering of measuring modules was tested as the system components were arranged and fixed to the streamers. After measurements were completed, the accuracy and speed of data downloading from the internal memory (SDHC 32GB WiFi) was determined. Additionally, the functionality of automatic battery recharging, the maximum survey duration, and the reliability of battery discharge signalling were assessed.

1D Seismic reflection technique to increase depth information in surface seismic investigations

NASA Astrophysics Data System (ADS)

Camilletti, Stefano; Fiera, Francesco; Umberto Pacini, Lando; Perini, Massimiliano; Prosperi, Andrea

2017-04-01

1D seismic methods, such as MASW Re.Mi. and HVSR, have been extensively used in engineering investigations, bedrock research, Vs profile and to some extent for hydrologic applications, during the past 20 years. Recent advances in equipment, sound sources and computer interpretation techniques, make 1D seismic methods highly effective in shallow subsoil modeling. Classical 1D seismic surveys allows economical collection of subsurface data however they fail to return accurate information for depths greater than 50 meters. Using a particular acquisition technique it is possible to collect data that can be quickly processed through reflection technique in order to obtain more accurate velocity information in depth. Furthermore, data processing returns a narrow stratigraphic section, alongside the 1D velocity model, where lithological boundaries are represented. This work will show how collect a single-CMP to determine: (1) depth of bedrock; (2) gravel layers in clayey domains; (3) accurate Vs profile. Seismic traces was processed by means a new software developed in collaboration with SARA electronics instruments S.r.l company, Perugia - ITALY. This software has the great advantage of being able to be used directly in the field in order to reduce the times elapsing between acquisition and processing.

Nitrogen starvation affects bacterial adhesion to soil

PubMed Central

Borges, Maria Tereza; Nascimento, Antônio Galvão; Rocha, Ulisses Nunes; Tótola, Marcos Rogério

2008-01-01

One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation. PMID:24031246

Microbial community structure and diversity in the soil spatial profile of 5-year-old Robinia pseudoacacia 'Idaho,' determined by 454 sequencing of the 16S RNA gene.

PubMed

Chang, Yanping; Bu, Xiangpan; Niu, Weibo; Xiu, Yu; Wang, Huafang

2013-01-01

Relatively little information is available regarding the variability of microbial communities inhabiting deeper soil layers. We investigated the distribution of soil microbial communities down to 1.2 m in 5-year-old Robinia pseudoacacia 'Idaho' soil by 454 sequencing of the 16S RNA gene. The average number of sequences per sample was 12,802. The Shannon and Chao 1 indices revealed various relative microbial abundances and even distribution of microbial diversity for all evaluated sample depths. The predicted diversity in the topsoil exceeded that of the corresponding subsoil. The changes in the relative abundance of the major soil bacterial phyla showed decreasing, increasing, or no consistent trends with respect to sampling depth. Despite their novelty, members of the new candidate phyla OD1 and TM7 were widespread. Environmental variables affecting the bacterial community within the environment appeared to differ from those reported previously, especially the lack of detectable effect from pH. Overall, we found that the overall relative abundance fluctuated with the physical and chemical properties of the soil, root system, and sampling depth. Such information may facilitate forest soil management.

Understanding Biophysical Interactions In The Great Barrier Reef Catchments: Better Landscape Management For Water Quality Outcomes

NASA Astrophysics Data System (ADS)

Bui, E. N.; Wilkinson, S. N.; Bartley, R.

2014-12-01

Sediment input to the Great Barrier Reef (GBR) lagoon has had deleterious impacts on seagrass and coral ecosystems. The response of the Australian government has been to develop policies to: (i) reverse the impact of threats from sediments and nutrients, and improve water quality and aquatic health of the GBR lagoon; and (ii) to facilitate the uptake of sustainable farming and land management practices that deliver improved ecosystem services, by at least 30 per cent of farmers. The Reef2050 Long term sustainability plan aims to identify priority locations for on-ground investment of remediation options that will result in a reduction of constituent loads to the GBR. Recent sediment tracing studies indicate that subsoil from erosion features such as gullies and channel banks are the dominant contributors of sediment in the GBR catchments. Better control of gully and streambank erosion and restoration of riparian habitats are therefore necessary. Here we review the evidence for bank erosion in the GBR catchments and how scientific evidence on feedback relationships between climate- geochemistry-vegetation-landforms can be used to develop better guidelines for streambank and gully re-vegetation.

Exploration of geo-mineral compounds in granite mining soils using XRD pattern data analysis

NASA Astrophysics Data System (ADS)

Koteswara Reddy, G.; Yarakkula, Kiran

2017-11-01

The purpose of the study was to investigate the major minerals present in granite mining waste and agricultural soils near and away from mining areas. The mineral exploration of representative sub-soil samples are identified by X-Ray Diffractometer (XRD) pattern data analysis. The morphological features and quantitative elementary analysis was performed by Scanning Electron Microscopy-Energy Dispersed Spectroscopy (SEM-EDS).The XRD pattern data revealed that the major minerals are identified as Quartz, Albite, Anorthite, K-Feldspars, Muscovite, Annite, Lepidolite, Illite, Enstatite and Ferrosilite in granite waste. However, in case of agricultural farm soils the major minerals are identified as Gypsum, Calcite, Magnetite, Hematite, Muscovite, K-Feldspars and Quartz. Moreover, the agricultural soils neighbouring mining areas, the minerals are found that, the enriched Mica group minerals (Lepidolite and Illite) the enriched Orthopyroxene group minerals (Ferrosilite and Enstatite). It is observed that the Mica and Orthopyroxene group minerals are present in agricultural farm soils neighbouring mining areas and absent in agricultural farm soils away from mining areas. The study demonstrated that the chemical migration takes place at agricultural farm lands in the vicinity of the granite mining areas.

Sulphur and oxygen isotope analysis to identify sources of sulphur in gypsum-rich black crusts developed on granites.

PubMed

Rivas, T; Pozo, S; Paz, M

2014-06-01

We describe the results of sulphur and oxygen isotope analyses used to identify sources of the gypsum present in black crusts that grow on the granite of historical buildings. The crusts were sampled at various locations in and near the city of Vigo (NW Spain) and were analysed for their sulphur content and δ(34)S and δ(18)O isotope ratios. Sampled crusts had δ(34)S values of 7.3‰ to 12.9‰ and δ(18)O values of 6.56‰ to 12.51‰. Sampled as potential sulphur sources were bulk depositions, seawater, foundation, ashlar and construction materials and combustion residues. The results indicated marine and, to a lesser extent, anthropogenic, origins for the sulphur and ruled out the contribution of sub-soil sulphates by capillary rise from building foundations. Isotope analyses would indicate that cement and mortar were enriched in sulphur after their application in buildings. The fact that facade orientation (towards the sea or fossil fuel pollution sources) was correlated with sulphur isotope distribution pointed to various contributions to black crust formation. Copyright © 2014 Elsevier B.V. All rights reserved.

Stability of organic carbon in deep soil layers controlled by fresh carbon supply.

PubMed

Fontaine, Sébastien; Barot, Sébastien; Barré, Pierre; Bdioui, Nadia; Mary, Bruno; Rumpel, Cornelia

2007-11-08

The world's soils store more carbon than is present in biomass and in the atmosphere. Little is known, however, about the factors controlling the stability of soil organic carbon stocks and the response of the soil carbon pool to climate change remains uncertain. We investigated the stability of carbon in deep soil layers in one soil profile by combining physical and chemical characterization of organic carbon, soil incubations and radiocarbon dating. Here we show that the supply of fresh plant-derived carbon to the subsoil (0.6-0.8 m depth) stimulated the microbial mineralization of 2,567 +/- 226-year-old carbon. Our results support the previously suggested idea that in the absence of fresh organic carbon, an essential source of energy for soil microbes, the stability of organic carbon in deep soil layers is maintained. We propose that a lack of supply of fresh carbon may prevent the decomposition of the organic carbon pool in deep soil layers in response to future changes in temperature. Any change in land use and agricultural practice that increases the distribution of fresh carbon along the soil profile could however stimulate the loss of ancient buried carbon.

Specific features of the structure of microbial biomass in soils of annular mesodepressions in Lipetsk and Volgograd oblasts

NASA Astrophysics Data System (ADS)

Polyanskaya, L. V.; Sukhanova, N. I.; Chakmazyan, K. V.; Zvyagintsev, D. G.

2014-09-01

In the studied mesodepressions, the total microbial biomass in the gray forest and chernozemic soils decreases by two-three times under the impact of hydrogen flux from the subsoil horizons and soil waterlogging. The biomass decrease is especially pronounced in the lower soil horizons. The population density of bacteria in the soil samples subjected to the impact of hydrogen fluxes and temporary waterlogging decreases by two-three times in the upper horizons and by ten times in the lower horizons in comparison with that in the control samples. These factors also affect the length of fungal mycelium: it decreases by three-four times in the upper horizons and may completely disappear in the lower horizons. The reduction of the microbial biomass can be explained by the fact that hydrogen and waterlogging sharply decrease the soil redox potential, which retards the development of most microbes, except for methanogens and some other specialized groups of microorganisms. The domination of bacteria with diameter ≥0.23 and ≥0.38 μm and the decrease in the total number of bacteria have been found with the use of the cascade filtration method.

Modelling hydrological conditions in the maritime forest region of south-western Nova Scotia

NASA Astrophysics Data System (ADS)

Yanni, Shelagh; Keys, Kevin; Meng, Fan-Rui; Yin, Xiwei; Clair, Tom; Arp, Paul A.

2000-02-01

Hydrological processes and conditions were quantified for the Mersey River Basin (two basins: one exiting below Mill Falls, and one exiting below George Lake), the Roger's Brook Basin, Moosepit Brook, and for other selected locations at and near Kejimkujik National Park in Nova Scotia, Canada, from 1967 to 1990. Addressed variables included precipitation (rain, snow, fog), air temperature, stream discharge, snowpack accumulations, throughfall, soil and subsoil moisture, soil temperature and soil frost, at a monthly resolution. It was found that monthly per hectare stream discharge was essentially independent of catchment area from <20 km2 to more than 1000 km2. The forest hydrology model ForHyM2 was used to simulate monthly rates of stream discharge, throughfall and snowpack water equivalents for mature forest conditions. These simulations were in good agreement with the historical records once the contributions of fog and mist to the area-wide water budget were taken into account, each on a monthly basis. The resulting simulations establish a hydrologically consistent, continuous, comprehensive and partially verified record for basin-wide outcomes for all major hydrological processes and conditions, be these related to stream discharge, soil moisture, soil temperature, snowpack accumulations, soil frost, throughfall, interception and soil percolation.

S-World: A high resolution global soil database for simulation modelling (Invited)

NASA Astrophysics Data System (ADS)

Stoorvogel, J. J.

2013-12-01

There is an increasing call for high resolution soil information at the global level. A good example for such a call is the Global Gridded Crop Model Intercomparison carried out within AgMIP. While local studies can make use of surveying techniques to collect additional techniques this is practically impossible at the global level. It is therefore important to rely on legacy data like the Harmonized World Soil Database. Several efforts do exist that aim at the development of global gridded soil property databases. These estimates of the variation of soil properties can be used to assess e.g., global soil carbon stocks. However, they do not allow for simulation runs with e.g., crop growth simulation models as these models require a description of the entire pedon rather than a few soil properties. This study provides the required quantitative description of pedons at a 1 km resolution for simulation modelling. It uses the Harmonized World Soil Database (HWSD) for the spatial distribution of soil types, the ISRIC-WISE soil profile database to derive information on soil properties per soil type, and a range of co-variables on topography, climate, and land cover to further disaggregate the available data. The methodology aims to take stock of these available data. The soil database is developed in five main steps. Step 1: All 148 soil types are ordered on the basis of their expected topographic position using e.g., drainage, salinization, and pedogenesis. Using the topographic ordering and combining the HWSD with a digital elevation model allows for the spatial disaggregation of the composite soil units. This results in a new soil map with homogeneous soil units. Step 2: The ranges of major soil properties for the topsoil and subsoil of each of the 148 soil types are derived from the ISRIC-WISE soil profile database. Step 3: A model of soil formation is developed that focuses on the basic conceptual question where we are within the range of a particular soil property at a particular location given a specific soil type. The soil properties are predicted for each grid cell based on the soil type, the corresponding ranges of soil properties, and the co-variables. Step 4: Standard depth profiles are developed for each of the soil types using the diagnostic criteria of the soil types and soil profile information from the ISRIC-WISE database. The standard soil profiles are combined with the the predicted values for the topsoil and subsoil yielding unique soil profiles at each location. Step 5: In a final step, additional soil properties are added to the database using averages for the soil types and pedo-transfer functions. The methodology, denominated S-World (Soils of the World), results in readily available global maps with quantitative pedon data for modelling purposes. It forms the basis for the Global Gridded Crop Model Intercomparison carried out within AgMIP.

Long-term batch study of sorption, transformation and extractability to characterize the fate of the veterinary antibiotic sulfadiazine

NASA Astrophysics Data System (ADS)

Sittig, Stephan; Kasteel, Roy; Groeneweg, Joost; Vereecken, Harry

2010-05-01

The occurrence of veterinary antibiotic substances in various environmental compartments is of growing concern. Once released into the environment (e.g. via manure), these organic substances can cause changes in the composition of microbial populations, provoke the development and spreading of resistance genes and finally reach the food chain. The substance under study is the veterinary antibiotic sulfadiazine (SDZ), which belongs to the chemical group of the sulfonamides. These compounds are widely applied in animal husbandry. There are hardly any studies on the macroscopic sorption and desorption behaviour in combination with transformation processes, particularly investigating the sorbed fraction. We are conducting long-term batch sorption experiments to characterize the partitioning between the liquid and the solid phases as well as formation of transformation products. A sequential extraction procedure enables us to analyse the composition of the various sorbed fractions. We applied 14C-labelled SDZ in aqueous solution to fresh soil, originating from an agricultural field (silty loam). Adsorption and desorption studies are conducted for the duration of 60 d and 80 d, respectively. Unique setups for single time-steps allow us to trace the development of the partition process between the liquid and the solid phase and also partitioning within the solid phase. The composition of these liquid phases concerning the parent substance and the transformation products is analyzed. Using Radio-HPLC we find at least five transformation products: 4-hydroxy-sulfadiazine (4-OH-SDZ), 4-(2-iminopyrimidin-1(2H)-yl)-aniline (An-SDZ) and additionally three yet unknown products. By means of a sequential extraction, differently strong bound fractions of the compound can be distinguished. Extractions consist of a mild method (0.01 M CaCl2-solution; 24 h) followed by a methanol extraction (4 h). Finally, a residual fraction is gained by microwave extraction at an elevated temperature (150°C) and pressure (mixture of water and acetonitril, 4:1). Bound residues are determined by combustion. The course of the kinetic adsorption/desorption processes as well as the partitioning of the compound over the various solid phase fractions is observed. Sorption is time-dependent and strongly non-linear. The topsoil shows a significantly higher sorption affinity than the subsoil. While the amount of radioactivity sorbed to the soil matrix increases with time, the extractability decreases significantly, i. e. at the end of the experimental time there is no yield with mild extraction methods. On the contrary, after 60 d, there is still a considerably mass gained with the microwave extraction. Desorption is very slow due to hysteresis. In the topsoil transformation occurs with higher rates, leading to more detectable transformation products as in the subsoil. With our experimental setup it will be possible to set up a kinetic modell for the partitioning of the solute between the liquid and the solid phase. This description will also include an estimation of the transformation parameters.

Regional analysis of ground-water recharge: Chapter B in Ground-water recharge in the arid and semiarid southwestern United States (Professional Paper 1703)

USGS Publications Warehouse

Flint, Lorraine E.; Flint, Alan L.; Stonestrom, David A.; Constantz, Jim; Ferré, Ty P.A.; Leake, Stanley A.

2007-01-01

A modeling analysis of runoff and ground-water recharge for the arid and semiarid southwestern United States was performed to investigate the interactions of climate and other controlling factors and to place the eight study-site investigations into a regional context. A distributed-parameter water-balance model (the Basin Characterization Model, or BCM) was used in the analysis. Data requirements of the BCM included digital representations of topography, soils, geology, and vegetation, together with monthly time-series of precipitation and air-temperature data. Time-series of potential evapotranspiration were generated by using a submodel for solar radiation, taking into account topographic shading, cloudiness, and vegetation density. Snowpack accumulation and melting were modeled using precipitation and air-temperature data. Amounts of water available for runoff and ground-water recharge were calculated on the basis of water-budget considerations by using measured- and generated-meteorologic time series together with estimates of soil-water storage and saturated hydraulic conductivity of subsoil geologic units. Calculations were made on a computational grid with a horizontal resolution of about 270 meters for the entire 1,033,840 square-kilometer study area. The modeling analysis was composed of 194 basins, including the eight basins containing ground-water recharge-site investigations. For each grid cell, the BCM computed monthly values of potential evapotranspiration, soil-water storage, in-place ground-water recharge, and runoff (potential stream flow). A fixed percentage of runoff was assumed to become recharge beneath channels operating at a finer resolution than the computational grid of the BCM. Monthly precipitation and temperature data from 1941 to 2004 were used to explore climatic variability in runoff and ground-water recharge.The selected approach provided a framework for classifying study-site basins with respect to climate and dominant recharge processes. The average climate for all 194 basins ranged from hyperarid to humid, with arid and semiarid basins predominating (fig. 6, chapter A, this volume). Four of the 194 basins had an aridity index of dry subhumid; two of the basins were humid. Of the eight recharge-study sites, six were in semiarid basins, and two were in arid basins. Average-annual potential evapotranspiration showed a regional gradient from less than 1 m/yr in the northeastern part of the study area to more than 2 m/yr in the southwestern part of the study area. Average-annual precipitation was lowest in the two arid-site basins and highest in the two study-site basins in southern Arizona. The relative amount of runoff to in-place recharge varied throughout the study area, reflecting differences primarily in soil water-holding capacity, saturated hydraulic conductivity of subsoil materials, and snowpack dynamics. Climatic forcing expressed in El Niño and Pacific Decadal Oscillation indices strongly influenced the generation of precipitation throughout the study area. Positive values of both indices correlated with the highest amounts of runoff and ground-water recharge.

Decoupling the deep: crop rotations, fertilization and soil physico-chemical properties down the profile

NASA Astrophysics Data System (ADS)

Hobley, Eleanor; Honermeier, Bernd; Don, Axel; Amelung, Wulf; Kögel-Knabner, Ingrid

2017-04-01

Crop fertilization provides vital plant nutrients (e.g. NPK) to ensure yield security but is also associated with negative environmental impacts. In particular, inorganic, mineral nitrogen (Nmin) fertilization leads to emissions during its energy intensive production as well as Nmin leaching to receiving waters. Incorporating legumes into crop rotations can provide organic N to the soil and subsequent crops, reducing the need for mineral N fertilizer and its negative environmental impacts. An added bonus is the potential to enhance soil organic carbon stocks, thereby reducing atmospheric CO2 concentrations. In this study we assessed the effects of legumes in rotation and fertilization regimes on the depth distribution - down to 1 m - of total soil nitrogen (Ntot), soil organic carbon (SOC) as well as isotopic composition (δ13C, δ15N), electrical conductivity and bulk density as well as agricultural yields at a long-term field experiment in Gießen, Germany. Fertilization had significant but small impacts on the soil chemical environment, most particularly the salt content of the soil, with PK fertilization increasing electrical conductivity throughout the soil profile. Similarly, fertilization resulted in a small reduction of soil pH throughout the soil profile. N fertilization, in particular, significantly increased yields, whereas PK fertilizer had only marginal yield effects, indicating that these systems are N limited. This N limitation was confirmed by significant yield benefits with leguminous crops in rotation, even in combination with mineral N fertilizer. The soil was physically and chemically influenced by the choice of crop rotation. Adding clover as a green mulch crop once every 4 years resulted in an enrichment of total N and SOC at the surface compared with fava beans and maize, but only in combination with PK fertilization. In contrast, fava beans and to a lesser extent maize in rotation lowered bulk densities in the subsoil compared with clover. This resulted in a reduction of N density at depth, which was not mirrored in C densities, indicating that fava beans decouple C and N cycles in the deep soil profile. We then tested whether these effects are a result of plant (i.e. enhanced rooting depth associated with lowered subsoil bulk density) or microbial (i.e. N-cycling and denitrification processes) activities, by investigating the isotopic signatures of C and N down the profile. Our results indicate that the selection of crop rotation influences soil C and N cycling and depth distribution. Although mineral N fertilizer has significant benefits for yield, the choice of crop rotation has a greater influence on soil C and N cycling and specifically the addition of leguminous plants into rotation can provide additional yield benefits and stability. Incorporating legumes into crop rotations affects soil physical and chemical properties and decouples C and N cycles in the deep soil profile, indicating different nutrient and water cycling processes in the deep soil profile.

Geochemical signature and phytoremediation of urban soil: a case in Barcelona city

NASA Astrophysics Data System (ADS)

Rodríguez-Bocanegra, Javier; Roca, Núria; Febrero, Anna; Bort, Jordi

2016-04-01

The cleanup of contaminated places with heavy metals is necessary, but environmental remediation strategies are often expensive and energy consuming. Thus, it is important to develop low-cost and environmentally friendly strategies. Phytoremediation-based technologies could provide a long-lasting solution. The study area is located in Sants, a neighbourhood in Barcelona city (Catalonia, Spain). This place was an industrial area in the last century, which was occupied by a metal smelting industry. Nowadays, the neighbours want to cultivate vegetables in this location, but the history of this area suggests that the soil is polluted by elevated concentrations of heavy metals. The aim of this work was to determine heavy metal concentration in: a) soil, to know the degree of the soil pollution; b) roots and leaves of two plant species, Brassica juncea as an accumulator plant and Solanum lycopersicum as a crop plant, to know the capacity of each species to accumulate metals, and c) drainage water, to evaluate the heavy metal mobility. The main pollutants are Cu, Pb and Zn with topsoil total concentrations about 1355, 2230 and 6239 mg•kg-1, respectively. The established background upper limits in this area in mg•kg-1 were: Cu 145, Pb 91 and Zn 326. The same soil elements for available fractions, extracted with DTPA, were slightly elevated (9.6, 5.8 and 6.7 % of total concentration). The environmental pollution implies great extractability, suggesting the plants in these soils have facility with potentially toxic elements absorption. Instead, the concentrations in subsoil are lower than in topsoil. The concentrations of Cu, Pb and Zn in the plants' leaves are greater in B. juncea 170 ± 52.7, 137 ± 46.3 and 2365 ± 860.4 mg•kg-1, than in S. lycopersicum 102.5 ± 7.1, 22.5 ± 1.3 and 1002 ± 85.2 mg•kg-1 respectively. Furthermore, they are also greater in roots than in leaves. All of them are lower than the threshold to be considered like a hyperaccumulator species. However, Pb concentrations in a crop plant exceeded the 0.10 mg•kg-1 limit established for vegetables devoted for food in the European legislation. Part of these heavy metals were transferred to the drainage water. The range of topsoil with B. juncea drainage water values in μg•L-1 is as follows: Cu 115-162, Pb 23.0-32.0 and Zn 613.8-759.7. Unusual elevated concentrations of Pb (over 10 μg•L-1) were detected in drainage water. These values exceeded the acceptable toxic concentrations in waters, according to the Spanish legislation. Furthermore, the values for subsoil drainage water in μg•L-1 were also elevated (Cu 293-298, Pb 15.6-4.84 and Zn 189.5-120.0).

Controlling parameters of fluorescent tracer sorption on soils and sediments

NASA Astrophysics Data System (ADS)

Bork, Marcus; Graf-Rosenfellner, Markus; Lange, Jens; Lang, Friederike

2017-04-01

Fluorescent dyes like uranine (UR) and sulforhodamine B (SRB) have been widely used, especially for tracing hydrological processes. In the recent past, efforts have intensified to use fluorescent tracers also in soils, for example as proxies for organic pollutants. However, the sorption properties of both organic pollutants and fluorescent tracers have to be exactly known to succeed. Yet existing knowledge for soils is still incomplete and poorly standardized. For this reason, we carried out laboratory batch experiments to determine sorption isotherms of UR and SRB with varying pH, soil texture and organic carbon content (OC). As sorbents we used a sandy sediment with low OC, a silty loamy topsoil with 2.8 %-OC and a similar textured subsoil containing 0.6 %-OC. For both tracers six concentration steps each were prepared and shaken with the suspended sorbent for 42 h using a sorbent:solution ratio of 1:5. During the equilibration, the pH was repeatedly adjusted to 5.5, 6.5, and 7.5 by adding hydrochloric acid (HCl) or sodium hydroxide (NaOH). Subsequently, the tracer-sorbent-suspension was centrifuged and the fluorescence of the tracer in the supernatant was measured. In order to examine the influence of OC and the clay fraction on the tracer sorption, batch-experiments at pH 7.5 were also conducted with manipulated sorbents: top- and subsoil samples were treated with H2O2 to remove organic matter and the clay mineral montmorillonite was added to the sandy sediment to achieve final clay contents of 0.1 %, 0.5 %, 1 %, 2 %, 2.5 %, 5 % and 10 % clay. We observed a negative relationship between the linear sorption coefficient Kd and pH, which was stronger for UR than for SRB. Increasing numbers of negative sorption sites and functional groups of both tracers and sorbents with increasing pH might be the reason for this observation. Besides the pH-value, quantity and quality of clay and OC had a crucial influence on the sorption of UR and SRB in soils and sediment. As expected, increasing clay content, which is associated with an increasing specific surface and therefore more sorption sites, led to an increasing sorption of UR and SRB. Here, after the addition of 4 % of the clay mineral montmorillonite, nearly 100 % of both tracers were sorbed. Furthermore, OC influenced the sorption of UR and SRB in different ways: while the sorption of UR increased, the sorption of SRB decreased with increasing OC. In conclusion, the sorption behaviour of the fluorescent tracers UR and SRB in soils is very complex, and for appropriate application, the physico-chemical properties of the respective soils or sediments have to be considered. These conditions essentially determine if the respective tracer shows a conservative or non-conservative behaviour. With these aspects in mind, applying SRB and UR has the potential to be a cheap and fast method to estimate the fate of pollutants in soils or sediments.

Biodiversity effects on the water balance of an experimental grassland

NASA Astrophysics Data System (ADS)

Leimer, Sophia; Kreutziger, Yvonne; Rosenkranz, Stephan; Beßler, Holger; Engels, Christof; Oelmann, Yvonne; Weisser, Wolfgang W.; Wirth, Christian; Wilcke, Wolfgang

2013-04-01

Plant species richness increases aboveground biomass production in biodiversity experiments. Biomass production depends on and feeds back to the water balance, but it remains unclear how plant species richness influences soil water contents and water fluxes (actual evapotranspiration (ETa), downward flux (DF), and upward flux (UF)). Our objective was to determine the effects of plant species and functional richness and functional identity on soil water contents and water fluxes for two soil depths (0-0.3 and 0.3.-0.7 m). To achieve this, we used a water balance model in connection with Bayesian hierarchical modeling. We monitored soil water contents on 86 plots of a grassland plant diversity experiment in Jena, Germany between July 2002 and January 2006. In the field experiment, plant species richness (0, 1, 2, 4, 8, 16, 60) and functional group composition (0-4 functional groups: legumes, grasses, non-leguminous tall herbs, non-leguminous small herbs) were manipulated in a factorial design. Climate data (air temperature, precipitation, wind velocity, relative humidity, global radiation, soil moisture) was measured at a central climate station between July 2002 and December 2007. Root biomass data from July 2006 was available per plot. Missing water contents per plot and depth were estimated in weekly resolution for the years 2003-2007 with a Bayesian hierarchical model using measured water contents per plot and centrally measured soil moisture. To obtain ETa, DF, and UF of the two different soil depths, we modified a soil water balance model which had been developed for our study site. The model is based on changes in soil water content between subsequent observation dates and modeled potential evapotranspiration which was partitioned between soil layers according to percentage of root biomass. The presence of specific functional groups significantly changed water contents and fluxes with partly opposing effects in the two soil depths. Presence of grasses decreased water contents in both depths, DF in topsoil, and ETa in subsoil, but increased ETa in topsoil. As grasses produce less shade than other plant functional groups because of their leaf morphology, higher ETa in topsoil could be explained by higher soil evaporation. Moreover, grasses have an extensive, shallow rooting system which facilitates exhaustive water use from the upper soil layer and therefore probably decreases water contents and DF. Species richness did not significantly affect water contents and fluxes in both soil layers except that the relation between species richness and water contents in subsoil changed over time. This can be explained by two equivalent but opposite effects. Transpiration increases with biomass which is positively correlated with species richness. By contrast, soil evaporation decreases with species richness because the greater vegetation cover in species-rich communities produces more shade. We conclude that the contrasting effects of plant species richness on transpiration and evaporation counterbalance each other and that functional traits of specific plant functional groups mediate the biologically-induced changes in the water balance.

Terrestrial pyrogenic carbon export to fluvial ecosystems: Lessons learned from the White Nile watershed of East Africa

NASA Astrophysics Data System (ADS)

Güereña, David T.; Lehmann, Johannes; Walter, Todd; Enders, Akio; Neufeldt, Henry; Odiwour, Holiance; Biwott, Henry; Recha, John; Shepherd, Keith; Barrios, Edmundo; Wurster, Chris

2015-11-01

Pyrogenic carbon (PyC) is important because of its role in the global organic C (OC) cycle and in modifying soil properties. However, our understanding of PyC movement from terrestrial to fluvial ecosystems is not robust. This study examined (i) whether erosion or subsurface transport was more important for PyC export from headwaters, (ii) whether PyC was exported preferentially to total OC (TOC), and (iii) whether the movement of PyC from terrestrial to aquatic ecosystems provides an explanation for the coupling of PyC and non-PyC observed in rivers at a global scale. In the Guineo-Congolian highland forest region of western Kenya, duplicate catchments with sizes of 1-12 ha were equipped with stream gauges in primary forest and adjacent mixed agricultural landscapes that were cleared by fire 10, 16, or 62 years before. Stream water samples were taken weekly throughout 1 year and compared with runoff to assess PyC movement. Additional stream samples were taken from all major tributaries of the White Nile watershed of Lake Victoria. PyC was not found to be preferentially eroded relative to TOC or non-PyC, as topsoil (0-0.15 m) PyC concentrations (6.3 ± 0.3% of TOC; means and standard errors) were greater than runoff sediment (1.9 ± 0.4%) and dissolved PyC concentrations (2.0 ± 0.4%, n = 252). In addition, PyC proportions in eroded sediment were lower than and uncorrelated (r2 = 0.04; P = 0.14) with topsoil PyC. An enrichment of PyC was found with depth in the soil, from 6.3 ± 0.3% of TOC in the topsoil (0-0.15 m) to 12.3 ± 0.3% of TOC at 1-2 m. Base flow PyC proportions of TOC correlated well with subsoil PyC (r2 = 0.57; P < 0.05) but not with topsoil PyC (r2 = 0.18; P > 0.05). Similar PyC proportions were found in the studied headwater streams (2.7 ± 0.2%), their downstream inflow into Lake Victoria (3.7%), the other nine major rivers into Lake Victoria (4.9 ± 0.8%), and its outflow into the White Nile (1.1%). A strong positive correlation between dissolved PyC and non-PyC (r2 = 0.91; P < 0.0001) in the headwater streams reflect relationships previously seen for a range of globally important rivers, and contrasts with a negative relationship for suspended sediments (r2 = -0.5; P < 0.0001). The estimated PyC export from the Lake Victoria watershed of 11 Gg yr-1 may therefore originate to a large extent from subsoil pathways in dissolved form that appeared to be an important source of PyC in aquatic environments and may explain the coupling of PyC and non-PyC at a global scale.

Specific features of electric field in the atmosphere and Radon emanations in Tunkin Basin of Baikal rift zone

NASA Astrophysics Data System (ADS)

Soloviev, S.; Loktev, D.

2013-05-01

Development of methods for diagnosing local crust encourages finding new ways for preventing hazardous geologic phenomena. Using measurements of several geophysical fields in addition to seismic methods enables to improve the existing methods and increase their reliability. In summer of 2009 and 2010, complex geophysical acquisition company was organized in the Tunkin Basin of the Baikal rift zone in South-Eastern Siberia, that runs 200 km to East-West from the southern tip of Baikal. Stationary observations were carried out in the central part of the Tunkin Basin, at the Geophysical observatory "I" of Institute of Solar-Terrestrial Physics of Siberian Branch of RAS and "II" near the Arshan settlement. Along with observations of microseismic noise and electric field variations in soil, there were performed measurements of electric field strength (Ez) in lowest atmosphere and volumetric activity of natural Radon in subsoil. Meteorological parameters were monitored with the use of DavisVantagePro meteorological stations. The analysis of observations showed that characteristic features of electric field in near-surface atmosphere are majorly defined by complex orography of the place and, consequently, by quickly changing meteorological conditions: thunderstorm activity and other mesometeorological events (with characteristic scale of tens of km and few hours long) in nearby rocks. The results of Ez(t) measurements performed under "good" weather conditions showed that the character of field variations depended on the local time with their maximum in daylight hours and minimum in the night. The analysis of Radon volumetric activity evidenced that its variations are influenced by atmospheric pressure and tides, and such influence is different at points "I" and "II". In particular, the tidal and atmospheric influence on Radon variations is more pronounced at "II" if compared to "I", which can be explained by locations of the registration points. Registration Point "II" is located close to tectonic faults, while "I" is in the center of the basin with its quite thick layer of sediments. Axial section observations of spatial inhomogeneities of electric field and Radon emanation were set along and across the Tunkin Basin. Observation points were set 3 to 10 km apart depending on the local relief. Each point was registering for 60 min under the conditions of "good" weather. There were analysed changes in mean strength of electric field and Radon volumetric activity as a function of distance along the axial section. It was found out that volumetric activity and electric field strength change in phase opposition - radon volumetric activity increase results in more intense ionization in near-surface atmosphere and consequently to decrease in the electric field strength. The concentration of Radon in subsoil atmosphere increases, and electric field strength decreases when approaching to rift zones rimming the Tunkin Basin from North and South. The results of axial section observations can be successfully used when mapping geological inhomogeneities in the Earth's crust. The research was done with financial support of RFBR, project# 12-05-00578

Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

NASA Astrophysics Data System (ADS)

Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

2014-05-01

Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (<10 km long), while sub-soils account for 90 to 100% of sediment entering and being transported in the remaining ~50 km of the system. This shift in dominant sediment source material coincided with a large increase in channel cross sectional area (~20 to >200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all areas apart from the upper catchment. The enlargement and entrenchment of the channel downstream has also resulted in lateral disconnection between the channel and floodplain. In this case, a rapid reduction in radionuclide concentrations downstream does coincide with hydrogeomorphic changes, supporting their use for studying short-term sediment dynamics. These findings highlight the importance of understanding hydrogeomorphic processes and connectivity when interpreting sediment source and tracer data.

Soil process-oriented modelling of within-field variability based on high-resolution 3D soil type distribution maps.

NASA Astrophysics Data System (ADS)

Bönecke, Eric; Lück, Erika; Gründling, Ralf; Rühlmann, Jörg; Franko, Uwe

2016-04-01

Today, the knowledge of within-field variability is essential for numerous purposes, including practical issues, such as precision and sustainable soil management. Therefore, process-oriented soil models have been applied for a considerable time to answer question of spatial soil nutrient and water dynamics, although, they can only be as consistent as their variation and resolution of soil input data. Traditional approaches, describe distribution of soil types, soil texture or other soil properties for greater soil units through generalised point information, e.g. from classical soil survey maps. Those simplifications are known to be afflicted with large uncertainties. Varying soil, crop or yield conditions are detected even within such homogenised soil units. However, recent advances of non-invasive soil survey and on-the-go monitoring techniques, made it possible to obtain vertical and horizontal dense information (3D) about various soil properties, particularly soil texture distribution which serves as an essential soil key variable affecting various other soil properties. Thus, in this study we based our simulations on detailed 3D soil type distribution (STD) maps (4x4 m) to adjacently built-up sufficient informative soil profiles including various soil physical and chemical properties. Our estimates of spatial STD are based on high-resolution lateral and vertical changes of electrical resistivity (ER), detected by a relatively new multi-sensor on-the-go ER monitoring device. We performed an algorithm including fuzzy-c-mean (FCM) logic and traditional soil classification to estimate STD from those inverted and layer-wise available ER data. STD is then used as key input parameter for our carbon, nitrogen and water transport model. We identified Pedological horizon depths and inferred hydrological soil variables (field capacity, permanent wilting point) from pedotransferfunctions (PTF) for each horizon. Furthermore, the spatial distribution of soil organic carbon (SOC), as essential input variable, was predicted by measured soil samples and associated to STD of the upper 30 cm. The comprehensive and high-resolution (4x4 m) soil profile information (up to 2 m soil depth) were then used to initialise a soil process model (Carbon and Nitrogen Dynamics - CANDY) for soil functional modelling (daily steps of matter fluxes, soil temperature and water balances). Our study was conducted on a practical field (~32,000 m²) of an agricultural farm in Central Germany with Chernozem soils under arid conditions (average rainfall < 550 mm). This soil region is known to have differences in soil structure mainly occurring within the subsoil, since topsoil conditions are described as homogenous. The modelled soil functions considered local climate information and practical farming activities. Results show, as expected, distinguished functional variability, both on spatial and temporal resolution for subsoil evident structures, e.g. visible differences for available water capacity within 0-100 cm but homogenous conditions for the topsoil.

The Effect of Land Use Change on Transformation of Relief and Modification of Soils in Undulating Loess Area of East Poland

PubMed Central

Rejman, Jerzy; Rafalska-Przysucha, Anna; Rodzik, Jan

2014-01-01

The change of primary forest areas into arable land involves the transformation of relief and modification of soils. In this study, we hypothesized that relatively flat loess area was largely transformed after the change of land use due to erosion. The modifications in soil pedons and distribution of soil properties were studied after 185 years of arable land use. Structure of pedons and solum depth were measured in 128 and soil texture and soil organic carbon in 39 points. Results showed that soils of noneroded and eroded profiles occupied 14 and 50%, respectively, and depositional soils 36% of the area. As a consequence, the clay, silt, and SOC concentration varied greatly in the plowed layer and subsoil. The reconstructed profiles of eroded soils and depositional soils without the accumulation were used to develop the map of past relief. The average inclination of slopes decreased from 4.3 to 2.2°, and slopes >5° vanished in the present topography. Total erosion was 23.8 Mg ha−1 year−1. From that amount, 88% was deposited within the study area, and 12% was removed outside. The study confirmed the hypothesis of the significant effect of the land use change on relief and soils in loess areas. PMID:25614883

Overlap in nitrogen sources and redistribution of nitrogen between trees and grasses in a semi-arid savanna.

PubMed

Priyadarshini, K V R; Prins, Herbert H T; de Bie, Steven; Heitkönig, Ignas M A; Woodborne, Stephan; Gort, Gerrit; Kirkman, Kevin; Fry, Brian; de Kroon, Hans

2014-04-01

A key question in savanna ecology is how trees and grasses coexist under N limitation. We used N stable isotopes and N content to study N source partitioning across seasons from trees and associated grasses in a semi-arid savanna. We also used (15)N tracer additions to investigate possible redistribution of N by trees to grasses. Foliar stable N isotope ratio (δ(15)N) values were consistent with trees and grasses using mycorrhiza-supplied N in all seasons except in the wet season when they switched to microbially fixed N. The dependence of trees and grasses on mineralized soil N seemed highly unlikely based on seasonal variation in mineralization rates in the Kruger Park region. Remarkably, foliar δ(15)N values were similar for all three tree species differing in the potential for N fixation through nodulation. The tracer experiment showed that N was redistributed by trees to understory grasses in all seasons. Our results suggest that the redistribution of N from trees to grasses and uptake of N was independent of water redistribution. Although there is overlap of N sources between trees and grasses, dependence on biological sources of N coupled with redistribution of subsoil N by trees may contribute to the coexistence of trees and grasses in semi-arid savannas.

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions.

PubMed

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-04-04

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

Electromagnetic signal penetration in a planetary soil simulant: Estimated attenuation rates using GPR and TDR in volcanic deposits on Mount Etna

NASA Astrophysics Data System (ADS)

Lauro, S. E.; Mattei, E.; Cosciotti, B.; Di Paolo, F.; Arcone, S. A.; Viccaro, M.; Pettinelli, E.

2017-07-01

Ground-penetrating radar (GPR) is a well-established geophysical terrestrial exploration method and has recently become one of the most promising for planetary subsurface exploration. Several future landing vehicles like EXOMARS, 2020 NASA ROVER, and Chang'e-4, to mention a few, will host GPR. A GPR survey has been conducted on volcanic deposits on Mount Etna (Italy), considered a good analogue for Martian and Lunar volcanic terrains, to test a novel methodology for subsoil dielectric properties estimation. The stratigraphy of the volcanic deposits was investigated using 500 MHz and 1 GHz antennas in two different configurations: transverse electric and transverse magnetic. Sloping discontinuities have been used to estimate the loss tangents of the upper layer of such deposits by applying the amplitude-decay and frequency shift methods and approximating the GPR transmitted signal by Gaussian and Ricker wavelets. The loss tangent values, estimated using these two methodologies, were compared and validated with those retrieved from time domain reflectometry measurements acquired along the radar profiles. The results show that the proposed analysis, together with typical GPR methods for the estimation of the real part of permittivity, can be successfully used to characterize the electrical properties of planetary subsurface and to define some constraints on its lithology of the subsurface.

Fingerprinting aliphatic hydrocarbon pollutants over agricultural lands surrounding Tehran oil refinery.

PubMed

Bayat, Javad; Hashemi, Seyed Hossein; Khoshbakht, Korros; Deihimfard, Reza

2016-11-01

The analysis of aliphatic hydrocarbons, which are composed of n-alkanes as well as branched and cyclic alkanes, can be used to distinguish between the sources of hydrocarbon contamination. In this study, the concentration of aliphatic hydrocarbons, soil pH, and organic matter in agricultural soils located south of Tehran were monitored. Eighty-three soil samples were taken from two depth ranges of 0-30 and 30-60 cm. The results showed that aliphatic compounds ranged from 0.22-68.11 mg kg -1 at the top to 0.33-53.18 mg kg -1 at subsoil. The amount of hydrocarbons increases from the northern parts toward the south, and hydrocarbon pollutants originated from both petroleum and non-petroleum sources. Higher concentrations of aliphatic compounds in the southern parts indicated that, aside from the practice of irrigating with untreated wastewater, leakage from oil refinery storage tanks possibly contributed to soil pollution. The results also showed that several sources have polluted the agricultural soils. It is necessary to develop a new local pollution criterion as a diagnostic index that includes not only hydrocarbons but also other parameters such as heavy metal content in both soil and untreated wastewater, surface runoff, and other irrigation water resources to determine the exact origin of pollution.

Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau.

PubMed

Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

2016-08-16

Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland.

Peroxidase-catalyzed stabilization of 2,4-dichlorophenol in alkali-extracted soils.

PubMed

Palomo, Mónica; Bhandari, Alok

2011-01-01

Horseradish peroxidase- (HRP) mediated stabilization of phenolic contaminants is a topic of interest due to its potential for remediation of contaminated soils. This study evaluated the sorption of 2,4-dichlorophenol (DCP) and its HRP-mediated stabilization in two alkali-extracted soils. Alkali extraction reduced the soil organic matter (SOM) contents of the geomaterials and enriched the residual SOM with humin C. Sorption of DCP on these sorbents was complete within 1 d. However, most of the sorbed DCP was removed from the geomaterials by water and methanol, suggesting weak solute-sorbent interactions. The addition of HRP resulted in the generation of DCP polymerization products (DPP), which partitioned between the aqueous and solid phases. The DPP phase distribution was rapid and complete within 24 h. Between 70 and 90% of the added DCP was converted to DPP and up to 43% of the initial aqueous phase contaminant was transformed into a residue that was resistant to extraction with methanol. Bound residues of DPP increased with initial aqueous phase solute concentration and remained fairly constant after 7 d of contact. Contaminant stabilization was noted to be high in the humin-mineral geomaterial. Results illustrate that HRP may be effective in stabilizing phenolic contaminants in subsoils that are likely to contain SOM enriched in humin C.

Degradation rates of alachlor, atrazine and bentazone in the profiles of Polish Luvisols

NASA Astrophysics Data System (ADS)

Paszko, Tadeusz; Muszyński, Paweł

2017-07-01

The degradation rates of three herbicides (alachlor, atrazine, and bentazone) were examined according to OECD Guideline 307 in three profiles of grey-brown podzolic soil (Luvisol) in a laboratory experiment. The aim of the experiment was to determine herbicide degradation parameters and their relationships with soil properties. Degradation processes were effectively described by a first-order model. However, in some cases, the best results were produced by bi-phasic kinetics (hockey-stick and bi-exponential model). The degradation rates of the tested herbicides at 25°C and 40% maximum water holding capacity, established based on half-life values in the Ap horizon, increased in the following order: atrazine (32.6-42.8 days) < bentazone (3.4-16.6 days < alachlor (4.4-5.7 days). The correlation analysis and the Principal Component Analysis revealed significant positive correlations between the herbicide degradation rates and the organic matter content of soils. The depth-dependent degradation factors obtained for topsoil and two subsoil horizons (1: 0.42: 0.11 - based on average values, and 1: 0.31: 0.12 - based on median values) reflect the degradation abilities of Polish Luvisols. The values noted are soil-specific; therefore, they can also be applied to other pesticides in Polish Luvisols.

Natural ³⁷Ar concentrations in soil air: implications for monitoring underground nuclear explosions.

PubMed

Riedmann, Robin A; Purtschert, Roland

2011-10-15

For on-site inspections (OSI) under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) measurement of the noble gas ³⁷Ar is considered an important technique. ³⁷Ar is produced underground by neutron activation of Calcium by the reaction ⁴⁰Ca(n,α)³⁷Ar. The naturally occurring equilibrium ³⁷Ar concentration balance in soil air is a function of an exponentially decreasing production rate from cosmic ray neutrons with increasing soil depth, diffusive transport in the soil air, and radioactive decay (T(1/2): 35 days). In this paper for the first time, measurements of natural ³⁷Ar activities in soil air are presented. The highest activities of ~100 mBq m⁻³ air are 2 orders of magnitude larger than in the atmosphere and are found in 1.5-2.5 m depth. At depths > 8 m ³⁷Ar activities are < 20 mBq m⁻³ air. After identifying the main ³⁷Ar production and gas transport factors the expected global activity range distribution of ³⁷Ar in shallow subsoil (0.7 m below the surface) was estimated. In high altitude soils, with large amounts of Calcium and with low gas permeability, ³⁷Ar activities may reach values up to 1 Bq m⁻³.

Controls on the dynamics of dissolved organic matter in soils: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalbitz, K.; Solinger, S.; Park, J.H.

Dissolved organic matter (DOM) in soils plays an important role in the biogeochemistry of carbon, nitrogen, and phosphorus, in pedogenesis, and in the transport of pollutants in soils. The aim of this review is to summarize the recent literature about controls on DOM concentrations and fluxes in soils. The authors focus on comparing results between laboratory and field investigations and on the differences between the dynamics of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP). Both laboratory and field studies show that litter and humus are the most important DOM sources in soils. However, it is impossible to quantifymore » the individual contributions of each of these sources to DOM release. In addition, it is not clear how changes in the pool sizes of litter or humus may affect DOM release. High microbial activity, high fungal abundance, and any conditions that enhance mineralization all promote high DOM concentrations. However, under field conditions, hydrologic variability in soil horizons with high carbon contents may be more important than biotic controls. In subsoil horizons with low carbon contents, DOM may be adsorbed strongly to mineral surfaces, resulting in low DOM concentrations in the soil solution. There are strong indications that microbial degradation of DOM also controls the fate of DOM in the soil.« less

Dynamic analysis of slab track on multi-layered transversely isotropic saturated soils subjected to train loads

NASA Astrophysics Data System (ADS)

Zhan, Yongxiang; Yao, Hailin; Lu, Zheng; Yu, Dongming

2014-12-01

The dynamic responses of a slab track on transversely isotropic saturated soils subjected to moving train loads are investigated by a semi-analytical approach. The track model is described as an upper Euler beam to simulate the rails and a lower Euler beam to model the slab. Rail pads between the rails and slab are represented by a continuous layer of springs and dashpots. A series of point loads are formulated to describe the moving train loads. The governing equations of track-ground systems are solved using the double Fourier transform, and the dynamic responses in the time domain are obtained by the inverse Fourier transform. The results show that a train load with high velocity will generate a larger response in transversely isotropic saturated soil than the lower velocity load, and special attention should be paid on the pore pressure in the vicinity of the ground surface. The anisotropic parameters of a surface soil layer will have greater influence on the displacement and excess pore water pressure than those of the subsoil layer. The traditional design method taking ground soil as homogeneous isotropic soil is unsafe for the case of RE < 1 and RG < 1, so a transversely isotropic foundation model is of great significance to the design for high train velocities.

Water age and stream solute dynamics at the Hubbard Brook Experimental Forest (US)

NASA Astrophysics Data System (ADS)

Botter, Gianluca; Benettin, Paolo; McGuire, Kevin; Rinaldo, Andrea

2016-04-01

The contribution discusses experimental and modeling results from a headwater catchment at the Hubbard Brook Experimental Forest (New Hampshire, USA) to explore the link between stream solute dynamics and water age. A theoretical framework based on water age dynamics, which represents a general basis for characterizing solute transport at the catchment scale, is used to model both conservative and weathering-derived solutes. Based on the available information about the hydrology of the site, an integrated transport model was developed and used to estimate the relevant hydrochemical fluxes. The model was designed to reproduce the deuterium content of streamflow and allowed for the estimate of catchment water storage and dynamic travel time distributions (TTDs). Within this framework, dissolved silicon and sodium concentration in streamflow were simulated by implementing first-order chemical kinetics based explicitly on dynamic TTD, thus upscaling local geochemical processes to catchment scale. Our results highlight the key role of water stored within the subsoil glacial material in both the short-term and long-term solute circulation at Hubbard Brook. The analysis of the results provided by the calibrated model allowed a robust estimate of the emerging concentration-discharge relationship, streamflow age distributions (including the fraction of event water) and storage size, and their evolution in time due to hydrologic variability.

Functional microbial community response to nutrient pulses by artificial groundwater recharge practice in surface soils and subsoils.

PubMed

Schütz, Kirsten; Kandeler, Ellen; Nagel, Peter; Scheu, Stefan; Ruess, Liliane

2010-06-01

Subsurface microorganisms are essential constituents of the soil purification processes associated with groundwater quality. In particular, soil enzyme activity determines the biodegradation of organic compounds passing through the soil profile. Transects from surface soil to a depth of 3.5 m were investigated for microbial and chemical soil characteristics at two groundwater recharge sites and one control site. The functional diversity of the microbial community was analyzed via the activity of eight enzymes. Acid phosphomonoesterase was dominant across sites and depths, followed by L-leucine aminopeptidase and beta-glucosidase. Structural [e.g. phospholipid fatty acid (PLFA) pattern] and functional microbial diversities were linked to each other at the nonwatered site, whereas amendment with nutrients (DOC, NO(3)(-)) by flooding uncoupled this relationship. Microbial biomass did not differ between sites, whereas microbial respiration was the highest at the watered sites. Hence, excess nutrients available due to artificial groundwater recharge could not compensate for the limitation by others (e.g. phosphorus as assigned by acid phosphomonoesterase activity). Instead, at a similar microbial biomass, waste respiration via overflow metabolism occurred. In summary, ample supply of carbon by flooding led to a separation of decomposition and microbial growth, which may play an important role in regulating purification processes during groundwater recharge.

Steam stripping of the unsaturated zone of contaminated sub-soils: The effect of diffusion/dispersion in the start-up phase

NASA Astrophysics Data System (ADS)

Brouwers, H. J. H.; Gilding, B. H.

2006-02-01

The unsteady process of steam stripping of the unsaturated zone of soils contaminated with volatile organic compounds (VOCs) is addressed. A model is presented. It accounts for the effects of water and contaminants remaining in vapour phase, as well as diffusion and dispersion of contaminants in this phase. The model has two components. The first is a one-dimensional description of the propagation of a steam front in the start-up phase. This is based on Darcy's law and conservation laws of mass and energy. The second component describes the transport of volatile contaminants. Taking the view that non-equilibrium between liquid and vapour phases exists, it accounts for evaporation, transport, and condensation at the front. This leads to a moving-boundary problem. The moving-boundary problem is brought into a fixed domain by a suitable transformation of the governing partial differential equations, and solved numerically. For a broad range of the governing dimensionless numbers, such as the Henry, Merkel and Péclet numbers, computational results are discussed. A mathematical asymptotic analysis supports this discussion. The range of parameter values for which the model is valid is investigated. Diffusion and dispersion are shown to be of qualitative importance, but to have little quantitative effect in the start-up phase.

Biochar increased water holding capacity but accelerated organic carbon leaching from a sloping farmland soil in China.

PubMed

Liu, Chen; Wang, Honglan; Tang, Xiangyu; Guan, Zhuo; Reid, Brian J; Rajapaksha, Anushka Upamali; Ok, Yong Sik; Sun, Hui

2016-01-01

A hydrologically contained field study, to assess biochar (produced from mixed crop straws) influence upon soil hydraulic properties and dissolved organic carbon (DOC) leaching, was conducted on a loamy soil (entisol). The soil, noted for its low plant-available water and low soil organic matter, is the most important arable soil type in the upper reaches of the Yangtze River catchment, China. Pore size distribution characterization (by N2 adsorption, mercury intrusion, and water retention) showed that the biochar had a tri-modal pore size distribution. This included pores with diameters in the range of 0.1-10 μm that can retain plant-available water. Comparison of soil water retention curves between the control (0) and the biochar plots (16 t ha(-1) on dry weight basis) demonstrated biochar amendment to increase soil water holding capacity. However, significant increases in DOC concentration of soil pore water in both the plough layer and the undisturbed subsoil layer were observed in the biochar-amended plots. An increased loss of DOC relative to the control was observed upon rainfall events. Measurements of excitation-emission matrix (EEM) fluorescence indicated the DOC increment originated primarily from the organic carbon pool in the soil that became more soluble following biochar incorporation.

Groundwater nutrient concentrations during prairie reconstruction on an Iowa landscape

USGS Publications Warehouse

Tomer, M.D.; Schilling, K.E.; Cambardella, C.A.; Jacobson, P.; Drobney, P.

2010-01-01

One anticipated benefit of ecosystem restoration is water quality improvement. This study evaluated NO3-N and phosphorus in subsurface waters during prairie establishment following decades of row-crop agriculture. A prairie seeding in late 2003 became established in 2006. Wells and suction cup samplers were monitored for NO3-N and phosphorus. Nitrate-N varied with time and landscape position. Non-detectable NO3-N concentrations became modal along ephemeral drainageways in 2006, when average concentrations in uplands first became <10mg NO3-NL-1. This decline continued and upland groundwater averaged near 2mg NO3-NL-1 after 2007. The longer time lag in NO3-N response in uplands was attributed to greater quantities of leachable N in upland subsoils. Spatial differences in vadose-zone travel times were less important, considering water table dynamics. Phosphorus showed a contrasting landscape pattern, without any obvious temporal trend. Phosphorus was greatest along and near ephemeral drainageways. Sediment accumulation from upland agricultural erosion provided a source of P along drainageways, where shallow, reductive groundwater increased P solubility. Phosphorus exceeded eutrophication risk thresholds in these lower areas, where saturation-excess runoff could readily transport P to surface waters. Legacy impacts of past agricultural erosion and sedimentation may include soluble phosphorus in shallow groundwater, at sites prone to saturation-excess runoff. ?? 2010.

Microbial Metagenomics Reveals Climate-Relevant Subsurface Biogeochemical Processes.

PubMed

Long, Philip E; Williams, Kenneth H; Hubbard, Susan S; Banfield, Jillian F

2016-08-01

Microorganisms play key roles in terrestrial system processes, including the turnover of natural organic carbon, such as leaf litter and woody debris that accumulate in soils and subsurface sediments. What has emerged from a series of recent DNA sequencing-based studies is recognition of the enormous variety of little known and previously unknown microorganisms that mediate recycling of these vast stores of buried carbon in subsoil compartments of the terrestrial system. More importantly, the genome resolution achieved in these studies has enabled association of specific members of these microbial communities with carbon compound transformations and other linked biogeochemical processes-such as the nitrogen cycle-that can impact the quality of groundwater, surface water, and atmospheric trace gas concentrations. The emerging view also emphasizes the importance of organism interactions through exchange of metabolic byproducts (e.g., within the carbon, nitrogen, and sulfur cycles) and via symbioses since many novel organisms exhibit restricted metabolic capabilities and an associated extremely small cell size. New, genome-resolved information reshapes our view of subsurface microbial communities and provides critical new inputs for advanced reactive transport models. These inputs are needed for accurate prediction of feedbacks in watershed biogeochemical functioning and their influence on the climate via the fluxes of greenhouse gases, CO2, CH4, and N2O. Copyright © 2016 Elsevier Ltd. All rights reserved.

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions

PubMed Central

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-01-01

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line. PMID:29617285

Significance of various soil amendments to borrow pit reclamation with loblolly pine and fescue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, C.R.; Marx, D.H.

Loblolly pine seedlings with ectomycorrhizae formed by Pisolithus tinctorius (Pt) or naturally occurring Thelephora terrestris (Tt) were planted on a borrow pit in South Carolina in plots with no amendment; with fertilizer plus dolomitic limestone alone and with pine bark or bottom ash or bark and ash together; or with dried sewage sludge alone and with bark or ash or bark and ash together. All plots were subsoiled, disked, and seeded to fescue grass before planting pine seedlings. Naturally occurring Pt formed abundant ectomycorrhizae on all Tt seedlings by the end of the first season, precluding any specific ectomycorrhizal fungusmore » effect for the duration of the study. Sewage sludge alone or with bark or ash amendments dramatically improved pine seedling growth and grass biomass in comparison with other soil treatments. Mean seedling volume (D/sup 2/H) was 28 times greater and grass biomass was five times greater in the sludge plots than on nonsludge plots. Generally, soil amended with sludge contained more N, P, organic matter, and had a higher cation exchange capacity than soil of other treatments. Foliage of pine seedlings in sludge-amended soil also contained more N and less Ca than other seedlings. The significance of these results to reclamation of borrow pits is discussed.« less

Potential of Svalbard reindeer winter droppings for emission/absorption of methane and nitrous oxide during summer

NASA Astrophysics Data System (ADS)

Hayashi, Kentaro; Cooper, Elisabeth J.; Loonen, Maarten J. J. E.; Kishimoto-Mo, Ayaka W.; Motohka, Takeshi; Uchida, Masaki; Nakatsubo, Takayuki

2014-06-01

Droppings of Svalbard reindeer (Rangifer tarandus platyrhynchus) could affect the carbon and nitrogen cycles in tundra ecosystems. The aim of this study was to evaluate the potential of reindeer droppings originating from the winter diet for emission and/or absorption of methane (CH4) and nitrous oxide (N2O) in summer. An incubation experiment was conducted over 14 days using reindeer droppings and mineral subsoil collected from a mound near Ny-Ålesund, Svalbard, to determine the potential exchanges of CH4 and N2O for combinations of two factors, reindeer droppings (presence or absence) and soil moisture (dry, moderate, or wet). A line transect survey was conducted to determine the distribution density of winter droppings at the study site. The incubation experiment showed a weak absorption of CH4 and a weak emission of N2O. Reindeer droppings originating from the winter diet had a negligible effect on the exchange fluxes of both CH4 and N2O. Although the presence of droppings resulted in a short-lasting increase in N2O emissions on day 1 (24 h from the start) for moderate and wet conditions, the emission rates were still very small, up to 3 μg N2O m-2 h-1.

Water–use efficiency of dryland wheat in response to mulching and tillage practices on the Loess Plateau

PubMed Central

Wang, Li-fang; Shangguan, Zhou-ping

2015-01-01

Mulching and tillage are widely considered to be major practices for improving soil and water conservation where water is scarce. This paper studied the effects of FM (flat mulching), RFM (ridge-furrow mulching), SM (straw mulching), MTMC (mulching with two materials combined), MOM (mulching with other materials), NT (no-tillage) ST (subsoiling tillage) and RT (rotational tillage) on wheat yield based on a synthesis of 85 recent publications (including 2795 observations at 24 sites) in the Loess Plateau, China. This synthesis suggests that wheat yield was in the range of 259–7898 kg ha−1 for FM and RFM. The sequence of water use efficiency (WUE) effect sizes was similar to that of wheat yield for the practices. Wheat yields were more sensitive to soil water at planting covered by plastic film, wheat straw, liquid film, water-permeable plastic film and sand compared to NT, ST and RT. RFM and RT increased the yields of wheat by 18 and 15%, respectively, and corresponding for WUE by 20.11 and 12.50%. This synthesis demonstrates that RFM was better for avoiding the risk of reduced production due to lack of precipitation; however, under conditions of better soil moisture, RT and MTMC were also economic. PMID:26192158

Modeling coupled sorption and transformation of 17β-estradiol-17-sulfate in soil-water systems

NASA Astrophysics Data System (ADS)

Bai, Xuelian; Shrestha, Suman L.; Casey, Francis X. M.; Hakk, Heldur; Fan, Zhaosheng

2014-11-01

Animal manure is the primary source of exogenous free estrogens in the environment, which are known endocrine-disrupting chemicals to disorder the reproduction system of organisms. Conjugated estrogens can act as precursors to free estrogens, which may increase the total estrogenicity in the environment. In this study, a comprehensive model was used to simultaneously simulate the coupled sorption and transformation of a sulfate estrogen conjugate, 17β-estradiol-17-sulfate (E2-17S), in various soil-water systems (non-sterile/sterile; topsoil/subsoil). The simulated processes included multiple transformation pathways (i.e. hydroxylation, hydrolysis, and oxidation) and mass transfer between the aqueous, reversibly sorbed, and irreversibly sorbed phases of all soils for E2-17S and its metabolites. The conceptual model was conceived based on a series of linear sorption and first-order transformation expressions. The model was inversely solved using finite difference to estimate process parameters. A global optimization method was applied for the inverse analysis along with variable model restrictions to estimate 36 parameters. The model provided a satisfactory simultaneous fit (R2adj = 0.93 and d = 0.87) of all the experimental data and reliable parameter estimates. This modeling study improved the understanding on fate and transport of estrogen conjugates under various soil-water conditions.

Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil

PubMed Central

Banning, Natasha C.; Maccarone, Linda D.; Fisk, Louise M.; Murphy, Daniel V.

2015-01-01

Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0–10 cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10–90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils. PMID:26053257

Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil.

PubMed

Banning, Natasha C; Maccarone, Linda D; Fisk, Louise M; Murphy, Daniel V

2015-06-08

Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0-10 cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10-90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils.

Soil-based treatment of partially treated liquid swine manure.

PubMed

Yang, H; Xiao, J; El-Din, M Gamal; Buchanan, I D; Bromley, D; Ikehata, K

2007-01-01

A soil-column system was tested for the removal of soluble organics and nutrients from partially treated liquid swine manure. The liquid manure was applied to the 900 mm deep (300 mm of local topsoil and 600 mm of local subsoil) soil columns continuously for an eight-week period, and leachate as well as soil samples were analysed. An effective liquid manure application rate of 17 mm d(-1) was determined based on a preliminary liquid manure soil-based treatment experiment. It was found that more than 90% of five-day biochemical oxygen demand, chemical oxygen demand, total Kjeldahl and ammonia nitrogen, and total phosphorus could be effectively removed from the liquid manure by the soil system. Nitrogen contents accumulated in the soil matrix mostly within the 0 to 300 mm depth, while no significant increase was observed in sub soils. Soil analyses indicated the occurrence of nitrification and denitrification in the soil columns. Nitrogen balance showed that about 42% of the applied nitrogen was lost from the system during the liquid manure soil-based treatment experiment, suggesting the emission of ammonia and other gaseous nitrogen generated through nitrification and denitrification. The leachate of the soil treatment system was used to irrigate Bermuda grass. No negative effect of leachate was observed on the plant growth.

Lateral loading on piles due to slope instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lupini, J.F.; Chacin, M.E.; Furiol, A.

1995-12-01

This paper presents the Caripito Oil Loading Terminal case history for which very flat slope instability was responsible for the failure and structural collapse of seven mooring and/or breasting dolphins, plus the collapse of all of the intermediate supports of catwalk bridges that provide access to the dolphins, from or to the loading platforms. These supports collapsed before the dolphins did as, in the whole, they were much weaker to support lateral thrusts, even though they were strengthened with additional piles, on several occasions. When movement of the dolphins first became apparent, a monitoring program was designed to measure themore » displacement of the pile caps. The primary cause for failure was the very weak nature of the subsoil, but the triggering mechanism was the need to dredge the bottom, further than previously in the past, because of the new recent condition of siltation and sedimentation and to accommodate larger tankers with larger draughts. Although most of the dolphins failed in a three year period, the trestles and the loading platforms have not shown, so far, significant signs of distress. This paper deals with the site assessment program, with what caused the failures, how the collapse occurred and the conclusions, that were drawn during the study.« less

Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau

PubMed Central

Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

2016-01-01

Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland. PMID:27527683

Investigations of the characteristics, origin, and residence time of the upland residual mantle of the Piedmont of Fairfax County, Virginia

USGS Publications Warehouse

Pavich, M.J.; Leo, G.W.; Obermeier, S.F.; Estabrook, J.R.

1989-01-01

Undisturbed cores of upland regolith developed from a variety of crystalline rocks of the Piedmont province in Fairfax County, Va., have been obtained by using a combination of Shelby tubes, Denison sampler, and modified diamond core drilling. The core study correlated variations in chemistry, mineralogy, and texture with engineering properties throughout individual weathering profiles and contrasted these parameters among weathering profiles developed from various parent rocks. Coring sites were chosen to obtain a maximum depth of weathering on diverse lithologies. The rocks that were investigated included metapelite, metagraywacke, granite, diabase, and serpentinite. Four to twelve samples per core were selected for analysis of petrography, texture, clay mineralogy, and major-element chemistry. The number of samples was determined on the basis of (1) the thickness of the weathering profile (from about 1 m in serpentinite to more than 30 m in pelitic schist) and (2) megascopic changes in the weathering profile. Shear strength and compressibility were determined on corresponding segments of core. Standard penetration tests were performed adjacent to coring sites to evaluate in-place engineering properties. The regolith profiles on all rocks can be subdivided into soil, massive subsoil, saprolite, and weathered rock zones. Major differences in thicknesses of these zones are related to parent rock. Total regolith thickness is related to saprolite thickness. Saprolite is thickest on quartzofeldspathic metapelite, metagraywacke, and granite; thinner on diabase; and thinnest on serpentinite. Thickness of saprolite is related to rock structure and mineralogy. Geochemical changes of saprolite developed from each rock type follow predictable trends from fresh rock to soil profile, with increases in Ti, AI, Fe 3 +, and H 2 0+relative to absolute losses of Si, Fe2+, Mg, Ca, and Na. These variations are more pronounced in the weathering profiles above mafic and ultramafic rocks than in those above metagraywacke. Clay minerals in granite, schist, and metagraywacke saprolites are kaolinite, dioctahedral vermiculite, interlayered mica-vermiculite, and minor illite. Gibbsite is developed in near-surface samples of schist. Standard penetration test data for the upper 7 m of saprolite above schist, metagraywacke, and granite suggest alternations between stronger and weaker horizons that correlate with megascopic ally identified zones: soil, massive subsoil, and saprolite. The data correlate with density. Shear strength increases fairly regularly downward in the weathering profile. The engineering behavior of diabase saprolite is controlled by a dense, plastic, near-surface clay layer (montmorillonite and kaolinite) overlying rock that is weathered to a granular state (grus); the engineering properties of serpentinite are controlled by a very thin weathering profile. Similarities in regolith thickness, zonation, mineralogy, and chemistry of quartzofeldspathic rocks indicate the existence of fundamental geochemical and geomechanical controls on regolith evolution on the Piedmont upland. Data from the profiles of quartzofeldspathic regolith are used to construct a model suggesting the principal rate-control steps in the development and downwasting of the upland regolith. This model is consistent with available information about Piedmont hydrology and tectonic uplift.