Particle-Size Distribution in Soils of the Khankaiskiy Nature Reserve (Primorye Territory)

2021 ◽  
pp. 99-105
Author(s):  
Olga M. Golodnaya ◽  
Elena A. Zharikova
Keyword(s):  
Particle Size ◽  
Vertical Distribution ◽  
Nature Reserve ◽  
Decisive Role ◽  
Middle Part ◽  
Vertical Profiles ◽  
Physical Clay ◽  
Parent Materials ◽  
The Vertical Distribution ◽  
Alluvial Meadow

Soil texture is determined and the features of particle-size vertical distribution in soils of different landscapes of the Khankaiskiy Nature Reserve are considered. Three variants of the distribution of clay (<0.001 mm) and physical clay (<0.01 mm) fractions along the vertical profiles soils are identified: accumulative, regressive, with a maximum in the middle-profile horizon and with their approximately equal contents in the upper and the lower horizons. A regressive variant is revealed in burozems gleyic, podzoliс-brownzems, dark-humus gley and alluvial meadow gley soils. These soils are characterized by a medium loamy sandy-coarse-dusty composition of the upper horizons and a light- or medium-loamy composition of the middle and lower parts of the profile. The distribution of fine fractions along the profile is observed with a gradual decrease in their content with depth in typical burozems and alluvial meadow gley-ic soils, while the texture of the layer changes from medium loamy to light loamy. The vertical distribution of fine fractions with a maximum in the middle part of the profile is revealed in mucky gley soils. The profile is formed under the influence of a combination of the floodplain process with the introduction and redeposition of suspended particles and gleying. The lithological specificity of the accumulation of the initial parent materials plays a decisive role in the differentiation of fine fractions in the soil profile.

scholarly journals FEATURES OF TEXURE OF SOILS OF THE KHANKAISKIY NATURE RESERVE

2021 ◽  
Author(s):  
О.М. Голодная ◽  
Е.А. Жарикова
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Granulometric Composition ◽  
Nature Reserve ◽  
Fine Sand ◽  
Soil Profiles ◽  
Physical Clay ◽  
Flood Zone ◽  
Alluvial Meadow

Изучение гранулометрического состава почв Ханкайского заповедника показало, что профили почв представляют собой многослойные спектры различного литологического сложения. Сложность почвенных профилей по гранулометрическому составу определяется степенью проявления поемного и аллювиального процессов, литологическими особенностями почвообразующего материала. По типу сложения выделено несколько литологических групп. Темно-гумусовые глеевые, аллювиальные луговые глеевые почвы и буроземы глееватые отличаются резкой дифференциацией профиля по гранулометрическому составу на верхнюю легкую и нижнюю глинистую толщу. Для этих почв отмечено наибольшее содержание фракций физической глины и ила по всему почвенному профилю. Буроземы типичные и аллювиальные луговые глееватые, вышедшие из зоны затопления, характеризуются литологически однородным легким составом. В этих почвах выявлено высокое содержание фракций мелкого песка. The soil profiles the Khankaiskiy Nature Reserve represent multilayer spectra of various lithological addition. The complexity of soil profiles in terms of particle-size distribution is determined by the degree of manifestation of soil and alluvial processes, lithological features of soil-forming material. Several lithological groups are distinguished by the type of texture. Dark humus gley, alluvial meadow gley soils and burozem gleyic shrouds are distinguished by a sharp differentiation of the profile by granulometric composition into an upper light and lower clay thickness. The largest content of fractions of physical clay and silt was noted throughout the profiles for these soils. Burozem typical and alluvial meadow gleyic soils that have emerged from the flood zone characterize this with a lithologically homogeneous light composition. A high content of fine sand fractions was revealed in these soils.

Is aerosol optical depth a good metric to map dust properties? Lessons learned from AER-D

2020 ◽  
Author(s):  
Franco Marenco ◽  
Claire Ryder ◽  
Victor Estelles ◽  
Debbie O'Sullivan
Keyword(s):  
Remote Sensing ◽  
Particle Size ◽  
Vertical Distribution ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Field Experiments ◽  
Saharan Air Layer ◽  
Validation Experiment ◽  
Operational Models ◽  
The Vertical Distribution

<p>The main observable quantity used on a global scale to map aerosols is aerosol optical depth (AOD), from ground-based and satellite remote sensing. It is at the same time an optical property and a vertically integrated quantity, and it is commonly used as the main metric towards which to pull aerosol models, through data assimilation, verification, and tuning. Here we introduce a few reflections on how to better constrain our knowledge of the Saharan Air Layer and its associated mineral dust, following results from the AER-D campaign.</p><p>AER-D was a small field experiment in the Eastern Atlantic during August 2015, based on the opportunity given by the simultaneous ICE-D experiment. The purpose of AER-D was to investigate the physical properties of the Saharan Air Layer, and to assess and validate remote sensing and modelling products. The FAAM atmospheric research aircraft was used as a flying laboratory, and it carried a full set of instruments aimed at both in-situ sampling and remote sensing.</p><p>A broad distribution of particle sizes was consistently observed, with a significant giant mode up to 80 µm, generally larger than what was observed in previous experiments: we ascribe this to the set of instruments used, able to capture the full spectrum. We will discuss the representation of the particle size in operational models, and we will show that despite predicting an extinction coefficient of the correct order of magnitude, the particle size is generally underestimated. We will also discuss the implication of the giant particles for the ground-based remote sensing of columnar size-distributions from the SKYNET and AERONET networks (Sunphotometer Airborne Validation Experiment, which was a component of AER-D).</p><p>We will present the vertical structure of the Saharan Air Layer, and in particular one episode when the structure was very different than the one generally accepted in the conceptual model. Moreover, the comparison with the operational models showed that they can predict a correct aerosol optical depth (AOD, a vertically integrated quantity) despite missing the vertical distribution.</p><p>These findings lead to a series of reflections on how to better constrain our knowledge of the Saharan Air Layer and its representation in operational models. Size-resolved properties and the vertical distribution are essential companions of the global AOD observations commonly used operationally. We will also discuss objectives and ideas for future field experiments.</p>

scholarly journals ESTIMATION OF OCEANIC PARTICULATE ORGANIC CARBON WITH MACHINE LEARNING

2020 ◽  
Vol V-2-2020 ◽  
pp. 949-956
Author(s):  
R. Sauzède ◽  
J. E. Johnson ◽  
H. Claustre ◽  
G. Camps-Valls ◽  
A. B. Ruescas
Keyword(s):  
Machine Learning ◽  
Optical Properties ◽  
Organic Carbon ◽  
Vertical Distribution ◽  
Particulate Organic Carbon ◽  
Ocean Color ◽  
Global Scale ◽  
Vertical Profiles ◽  
The Vertical Distribution ◽  
Satellite Ocean Color

Abstract. Understanding and quantifying ocean carbon sinks of the planet is of paramount relevance in the current scenario of global change. Particulate organic carbon (POC) is a key biogeochemical parameter that helps us characterize export processes of the ocean. Ocean color observations enable the estimation of bio-optical proxies of POC (i.e. particulate backscattering coefficient, bbp) in the surface layer of the ocean quasi-synoptically. In parallel, the Argo program distributes vertical profiles of the physical properties with a global coverage and a high spatio-temporal resolution. Merging satellite ocean color and Argo data using a neural networkbased method has already shown strong potential to infer the vertical distribution of bio-optical properties at global scale with high space-time resolution. This method is trained and validated using a database of concurrent vertical profiles of temperature, salinity, and bio-optical properties, i.e. bbp, collected by Biogeochemical-Argo (BGC-Argo) floats, matched up with satellite ocean color products. The present study aims at improving this method by 1) using a larger dataset from BGC-Argo network since 2016 for training, 2) using additional inputs such as altimetry data, which provide significant information on mesoscale processes impacting the vertical distribution of bbp, 3) improving the vertical resolution of estimation, and 4) examining the potential of alternative machine learning-based techniques. As a first attempt with the new data, we used some feature-specific preprocessing routines followed by a Multi-Output Random Forest algorithm on two regions with different ocean dynamics: North Atlantic and Subtropical Gyres. The statistics and the bbp profiles obtained from the validation floats show promising results and suggest this direction is worth investigating even further at global scale.

scholarly journals Vertical distribution of sub-micron aerosol chemical composition from North-Western Europe and the North-East Atlantic

2009 ◽  
Vol 9 (2) ◽  
pp. 9117-9150
Author(s):  
W. T. Morgan ◽  
J. D. Allan ◽  
K. N. Bower ◽  
G. Capes ◽  
J. Crosier ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Vertical Distribution ◽  
Western Europe ◽  
Vertical Profiles ◽  
East Atlantic ◽  
Air Masses ◽  
North East ◽  
The North ◽  
The Vertical Distribution

Abstract. A synthesis of UK based airborne in-situ measurements of aerosol properties representing air masses from North-West Europe and the North-East Atlantic is presented. The major focus of the study is the vertical distribution of sub-micron aerosol chemical composition. Vertical profiles are derived from a Quadrupole Aerosol Mass Spectrometer (Q-AMS). Background sub-micron aerosol vertical profiles are identified and are primarily composed of organic matter and sulphate aerosol. Such background conditions occurred predominantly during periods associated with long-range air mass transport across the Atlantic. These instances may serve as useful model input of aerosol to Western Europe. Increased mass concentration episodes are coincident with European outflow and periods of stagnant/recirculating air masses. Such periods are characterised by significantly enhanced concentrations of nitrate aerosol relative to those of organic matter and sulphate. Periods of enhanced ground level PM2.5 loadings are coincident with instances of high nitrate mass fractions measured on-board the aircraft, indicating that nitrate is a significant contributor to regional pollution episodes. The vertical structure of the sulphate and organic aerosol profiles were shown to be primarily driven by large-scale dynamical processes. The vertical distribution of nitrate is likely determined by both dynamic and thermodynamic processes, with chemical partitioning of gas phase precursors to the particle phase occurring at lower temperatures at the top of the boundary layer. Such effects have profound implications for the aerosol's lifetime and subsequent impacts, highlighting the requirement for accurate representation of the aerosol vertical distribution.

scholarly journals High-resolution vertical distribution and sources of HONO and NO<sub>2</sub> in the nocturnal boundary layer in urban Beijing, China

2020 ◽  
Vol 20 (8) ◽  
pp. 5071-5092 ◽  
Author(s):  
Fanhao Meng ◽  
Min Qin ◽  
Ke Tang ◽  
Jun Duan ◽  
Wu Fang ◽  
...  
Keyword(s):  
High Resolution ◽  
Vertical Distribution ◽  
Inversion Layer ◽  
Ground Surface ◽  
Residual Layer ◽  
Urban Atmosphere ◽  
Vertical Profiles ◽  
Haze Episode ◽  
Beijing China ◽  
The Vertical Distribution

Abstract. Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), plays a key role in atmospheric chemistry, but its sources are still debated. The production of HONO on aerosol surfaces or on ground surfaces in nocturnal atmospheres remains controversial. The vertical profile provides vertical information on HONO and NO2 to understand the nocturnal HONO production and loss. In this study, we report the first high-resolution (<2.5 m) nocturnal vertical profiles of HONO and NO2 measured from in situ instruments on a movable container that was lifted on the side wiring of a 325 m meteorological tower in Beijing, China. High-resolution vertical profiles revealed the negative gradients of HONO and NO2 in nocturnal boundary layers, and a shallow inversion layer affected the vertical distribution of HONO. The vertical distribution of HONO was consistent with stratification and layering in the nocturnal urban atmosphere below 250 m. The increase in the HONO ∕ NO2 ratio was observed throughout the column from the clean episode to the haze episode, and relatively constant HONO∕NO2 ratios in the residual layer were observed during the haze episode. Direct HONO emissions from traffic contributed 29.3 % ± 12.4 % to the ambient HONO concentrations at night. The ground surface dominates HONO production by heterogeneous uptake of NO2 during clean episodes. In contrast, the HONO production on aerosol surfaces (30–300 ppt) explained the observed HONO increases (15–368 ppt) in the residual layer, suggesting that the aerosol surface dominates HONO production aloft during haze episodes, while the surface production of HONO and direct emissions into the overlying air are minor contributors. Average dry deposition rates of 0.74±0.31 and 1.55±0.32 ppb h−1 were estimated during the clean and haze episodes, respectively, implying that significant quantities of HONO could be deposited to the ground surface at night. Our results highlight the ever-changing contributions of aerosol and ground surfaces in nocturnal HONO production at different pollution levels and encourage more vertical gradient observations to evaluate the contributions from varied HONO sources.

Numerical and experimental study of the vertical distribution of velocity and hydraulic gradient in the capillary fringe

2021 ◽  
Author(s):  
Ali Mahdavi Mazdeh ◽  
Stefan Wohnlich
Keyword(s):  
Hydraulic Conductivity ◽  
Vertical Distribution ◽  
Water Content ◽  
Middle Part ◽  
Hydraulic Gradient ◽  
Upward Movement ◽  
Capillary Fringe ◽  
Gradient Profile ◽  
Vertical Hydraulic Gradient ◽  
The Vertical Distribution

&lt;p&gt;Capillary fringe plays an important role in the fate and transport of infiltrated solutes from agricultural lands. In this study, flow patterns and the vertical distribution of the velocity and hydraulic gradient inside the capillary fringe were investigated using FEFLOW calibrated by experimental data. An experimental box along with a real sample of capillary fringe from the study area (Sand and clay pit Br&amp;#252;ggen, Germany) was used for the experiments. The dimension of the filled part of the box was 0.75 m long, 0.55 m high, and 0.150 m wide. To maintain a constant hydraulic gradient throughout the experiments the upstream and downstream groundwater levels were fixed to 7 cm and 3 cm, respectively. The horizontal velocity at different points inside the capillary fringe and the vadose zone was measured by injecting the fluorescent dye tracer (Uranin). At the end of the experiments, the soil samples are collected from different parts of the box for water content measurement. The results indicate that FEFLOW successfully estimates water content, overall flow pattern, and more importantly horizontal movement inside the capillary fringe. The streamlines are parallel to the groundwater table in the middle part.&amp;#160; Based on both experimental and numerical results, while there is a downward movement near the outflow, an upward movement was seen near the inflow. In previous studies, the velocity profile inside the capillary fringe was estimated using Darcy&amp;#8217;s law, unsaturated hydraulic conductivity, and constant hydraulic gradient. The detailed comparison of measured water content and velocity with numerical modeling results showed that the constant hydraulic gradient assumption above the water table in previous studies is not valid. The vertical hydraulic gradient profile calculated by FEFLOW showed that the hydraulic gradient at the middle part of the box changes from 0.042 to 0.03. Moreover, the shape of the vertical hydraulic gradient profile is a function of the location in the box and soil type.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;Solute transport, Unsaturated zone, Streamline, Pore velocity, Hydraulic conductivity, FEFLOW&lt;/p&gt;

A method for retrieving the spatial distribution of trace gases using measurements of three ground-based MAX-DOAS instruments

2020 ◽  
Author(s):  
Michael Revesz ◽  
Stefan F. Schreier ◽  
Philipp Weihs ◽  
Tim Bösch ◽  
Kezia Lange ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Vertical Distribution ◽  
Trace Gases ◽  
Trace Gas ◽  
Wind Condition ◽  
Vertical Profiles ◽  
Open Issue ◽  
Using Data ◽  
Set Up ◽  
The Vertical Distribution

&lt;p&gt;Within the project VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols), a method was developed to retrieve the spatial distribution of trace gases using data from three ground based MAX-DOAS instruments and was applied on the example of NO&lt;sub&gt;2&lt;/sub&gt;. At three different locations in Vienna (Austria) MAX-DOAS instruments were installed performing measurements in the visible and UV spectral range. Currently, each instrument is set up to determine the column densities in different azimuthal directions and low elevation angles within approximately a horizontal plane. The different lines of sight of the three instruments intersect horizontally and can be used to estimate the horizontal spatial distribution of trace gases. With the knowledge of vertical profiles, even the vertical distribution can be estimated using this method.&amp;#160;&lt;/p&gt;&lt;p&gt;The intersections of the different lines of sight define segments along the slant columns for which the mass concentrations can be estimated. Knowledge about the vertical profiles for a chosen trace gas can be used to correct the retrieved trace gas concentration to specific altitudes above ground. Such corrections are also required since the three instruments were set up at different heights above ground, at different altitudes relative to sea level and with different elevation angles of the lowest viewing direction. One open issue for the retrieval process is the terrain in Vienna in combination with the prevailing wind condition that impacts the horizontal and vertical trace gas distribution and make the retrieval challenging.&amp;#160;&lt;/p&gt;

scholarly journals Size-Fractionated Filtration Combined with Molecular Methods Reveals the Size and Diversity of Picophytoplankton

Biology ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1280
Author(s):  
Xinze Shuwang ◽  
Jun Sun ◽  
Yuqiu Wei ◽  
Congcong Guo
Keyword(s):  
Flow Cytometry ◽  
Particle Size ◽  
Vertical Distribution ◽  
High Throughput ◽  
High Throughput Sequencing ◽  
Hypervariable Region ◽  
Pcr Amplification ◽  
Euphotic Zone ◽  
Vertical Distributions ◽  
The Vertical Distribution

In this study, flow cytometry (FCM) and size-fractionated filtration, together with high-throughput molecular sequencing methods (SM), were used to investigate picophytoplankton. A particle separation filter and a higher-throughput sequencing method were used to evaluate the composition of a euphotic zone of picophytoplankton—especially picoeukaryotic phytoplankton—in the Western Pacific, and the results of flow cytometry, which is a classic way to detect picophytoplankton, were used as a standard to evaluate the reliability of the results of the SMs. Within a water column of 200 m, six water depths (5, 25, 50, 113 (DCM), 150, and 200 m) were established. In order to further study the particle size spectra of the picophytoplankton, size-fractionated filtration was used to separate water samples from each water depth into three particle size ranges: 0.2–0.6, 0.6–1.2, and 1.2–2 μm. A total of 36 (6 × 3 × 2) samples were obtained through PCR amplification of the 18S rRNA V4 hypervariable region and 16S rRNA, which were biased toward phytoplankton plastids, and then high-throughput sequencing was performed. The estimation of the picophytoplankton diameter relied on forward scattering (FSC) through FCM. The estimation of the vertical distribution and diameter of the picophytoplankton using the SM was consistent with the results with FCM; thus, we believe that the estimation of picophytoplankton composition with the SM has value as a reference, although the size-fractionated filtration seemed to cause some deviations. In addition to Prochlorococcus and Synechococcus, the SM was used to evaluate the composition of picoeukaryotic phytoplankton, which mainly included Prymnesiophycea (Haptophyta) (38.15%), Cryptophyceae (Cryptophyta) (22.36%), Dictyochophyceae (Chrysophyta) (12.22%), and Mamiellophyceae (Chlorophyta) (3.31%). In addition, the SM also detected Dinophyceae (Dinoflagellata) (11.69%) sequences and a small number of Bacillariophyceae (Diatom) (1.64%) sequences, which are generally considered to have large particle sizes. The results of the SM also showed that the picoeukaryotic phytoplankton were not evenly distributed in the euphotic layer, and the vertical distributions of the different picoeukaryotic phytoplankton were different. An analysis of correlations with environmental factors showed that temperature was the main environmental factor controlling the vertical distribution of picophytoplankton.

Vertical profiles of Cs-137 in soil of the Matua Island ( the Central Kuril Islands, Russia) in 2017

2020 ◽  
Author(s):  
Borisov Alexander ◽  
Andrey Ivanov ◽  
Vitaly Linnik
Keyword(s):  
Vertical Distribution ◽  
Specific Activity ◽  
Global Fallout ◽  
Kuril Islands ◽  
Thin Layers ◽  
Maximum Height ◽  
Soil Core ◽  
Vertical Profiles ◽  
Matua Island ◽  
The Vertical Distribution

&lt;p&gt;The 2011 Fukushima-Daiichi nuclear power plant (FDNNP) accident resulted in the atmospheric releases of large quantities of man-made radionuclides. According to [1], Matua Island, located at a distance of more than 1000 km from FDNPP, was also subjected to minor radioactive contamination. Matua Island, 52.6 sq.km, a recent volcano with the highest point of 1446 m a.s.l. is located in the center of the Kuril Islands Arc. Volcanic soils are formed on stratified gravelly-stony tephra more than 60 cm thick, underlain by thin layers of volcanic slags. The latest catastrophic eruption which changed the landscape of the island occurred in 2009.&lt;/p&gt;&lt;p&gt;Studies of the vertical distribution of the Cs-137 in soils were carried out on four landscape catenas. The length of the catenas from the sea shore deep into the island ranged from 700 m (maximum height a.s.l. &amp;#160;70 m) to 3.3 km (height a.s.l. &amp;#160;450 m).&lt;/p&gt;&lt;p&gt;Soil core samples were taken in &amp;#160;summer 2017 at a depth of tephra, which was located at a depth of 10 to 25 cm. Soil was sliced into separate layers with a step of 2 to 5 cm.&lt;/p&gt;&lt;p&gt;The measurement activity concentrations of the Cs-137 in the soil samples were carried out on a low-background gamma spectrometer Canberra Industries. &amp;#160;The counting time&amp;#160; was fixed not less than 24 h to ensure that the statistical measurement error is small.&lt;/p&gt;&lt;p&gt;Cs-134, the &amp;#171;Fukushima&amp;#8221; fallout marker, due to the decay, was not detected. Therefore, it is difficult to accurately assess the Cs-137 contribution from the FDNNP accident from a global fallout.&lt;/p&gt;&lt;p&gt;The vertical distribution of Cs-137 is characterized by extreme heterogeneity, which reflects both the primary fallout conditions and the landscape conditions of the likely lateral redistribution. For &amp;#1089;atena 1 with a length of 1 km and an altitude&amp;#160; of 400 m, the number of pickets (P0, P1, etc. &amp;#8211; the numbering of pickets goes downhill), the specific activity of Cs-137 (Bq/kg) and the depth of the layer (cm) are given as follows: P0-27 Bq/kg (2-4 cm); P1 - 64 Bq/kg (6-8 cm); P2 &amp;#8211; 70 Bq/kg (8-10 cm); P3 - 53 Bq/kg (4-6 cm); P4 - 15 Bq/kg (0-5 cm).&amp;#160; Similar spatial&amp;#160; heterogeneity of the specific activity of Cs-137 and its depth penetration was also found for catena 3 with a length of 1250 m and a height of 75 m (the numbering of pickets goes up the slope): P1-137 Bq/kg (17-20 cm); P2-76 Bq/kg (0-5 cm); P3 - 35 Bq/kg (0-4 cm); P4 - 43 Bq/kg (3-6 cm); P6 &amp;#8211; 24 Bq/kg (5-10 cm).&lt;/p&gt;&lt;p&gt;The distribution of Cs-137 in individual soil layers was used to evaluate the empirically found shapes of the vertical profiles of radionuclide concentration. Cs-137 is believed here to be a&amp;#160; very valuable tracer&amp;#160; that&amp;#160; can be used to test&amp;#160; variability of vertical geochemical migration in Matua&amp;#160; landscapes.&lt;/p&gt;&lt;p&gt;[1]. Ramzaev V.P., Barkovsky A.N., Gromov A.V., Ivanov S.A., Kaduka M.V. Fukushima fallout in Sakhalin Region, Russia, part 1: &lt;sup&gt;137&lt;/sup&gt;Cs and &lt;sup&gt;134&lt;/sup&gt;Cs in grassland soils. Radiation Hygiene, 2018, Vol. 11, No. 1, pp. 25-42.&lt;/p&gt;

Dispersion of 226Ra in a Contaminated Environment

1988 ◽  
Vol 24 (1-4) ◽  
pp. 101-108 ◽  
Author(s):  
A.O. de Bettencourt ◽  
M.M.G.R. Texeira ◽  
M.J. Madruga ◽  
M.C. Faisca (INVITED)
Keyword(s):  
Organic Matter ◽  
Vertical Distribution ◽  
Gamma Spectrometry ◽  
Laboratory Experiments ◽  
Agricultural Soils ◽  
Soil Characteristics ◽  
Soil Samples ◽  
Vertical Profiles ◽  
Concentration Factors ◽  
The Vertical Distribution

Abstract A radium salts extraction factory was established in Portugal in 1908 in the northeastern part of the country. It was abandoned in the forties and is now in ruins. Wastes (mainly sands) highly contaminated with 226Ra were left near these ruins. Measurements were performed to evaluate the extent of the contamination due to the dispersion of radium around this site, using portable Gieger tube equipment as well as by gamma spectrometry analyses of soil samples. Vertical profiles of soil were taken to a depth of about 40 cm, and 5 cm sections were analysed by gamma spectrometry to evaluate the vertical distribution of 226Ra and 210Pb. Some soil characteristics, such as pH, organic matter and exchangeable calcium and radium were also analysed. The dispersion of radium seems to be mostly due to the removal of contaminated wastes by mechanical means, although some leaching may have occurred. Laboratory experiments were also conducted on sandy and agricultural soils to study the leaching of 226Ra and 210Pb with rainwater and to help explain the results obtained in the field study. The observed influence of different parameters on this leaching are briefly discussed. Vegetables grown on these soils (mainly cabbage) were analysed for their content of 226Ra and 210Pb in order to calculate concentration factors. For 226Ra, these range from about 7 x 10-3 to 7 x 10-2. For 210Pb, they range from about 10-3 to 2 x 10-2.

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