Determination of uranium, thorium and potassium contents in rock and soil samples using low-energy gamma ray spectrometry

A low-energy gamma ray spectrometric set-up for determination of uranium, thorium and potassium in rock and soil samples is described. The procedure described exploits the fact that a large proportion of gamma quanta produced in the Th and U decay series have energies of less than 1 MeV. The instrumental parameters such as sensitivity and detection limits for the low-energy region have been studied. The measuring conditions were optimized by suitably minimizing the background and by increasing the overall sensitivity with the help of proper geometry of measurement and sample parameters. High sensitivity and low detection limits for U and Th can be achieved using low-energy gamma ray spectrometry. The method provides a rapid analysis with a counting time of the order of a few minutes for each sample.     

An analysis of naturally occurring radionuclides and <Superscript>137</Superscript>Cs in the soils of urban areas using gamma-ray spectrometry

This study of environmental radioactivity was carried out in the soils of an urban area. Naturally occurring gamma-emitting radionuclides and man-made ¹³⁷Cs were found in the soil profiles collected from four parks in the central Belgrade city area and the soil layer was examined every 10 cm and to a depth of 50 cm. Radioisotope activity concentrations (Bq kg^?1) in the samples of urban soil using the gamma-ray spectrometry method were in the range of 14–46 for ²³⁸U, 33–50 for ²²⁶Ra, 29–63 for ²¹⁰Pb, 1.2–3.4 for ²³⁵U, 28–50 for ²³²Th, 424–576 for ⁴⁰K and 0.7–35.8 for ¹³⁷Cs. Some of the basic physicochemical soil properties (pH, organic matter content, calcium-carbonate content, particle size distribution) were determined to investigate the impact on the vertical distribution of radionuclides. The results of this investigation showed that variations of activity concentration ratios of radionuclides that belong to the same (²³⁸U/²²⁶Ra) or different radioactive series (²³²Th/²²⁶Ra; ²³⁵U/²³⁸U), including ²¹⁰Pb/¹³⁷Cs ratios could well be explained by the properties of the soil. Alkaline pH reaction, the accumulation of organic matter in the uppermost and of carbonates in the deepest layers of urban soil had an effect on ²³⁸U/²²⁶Ra, and ²¹⁰Pb/¹³⁷Cs activity concentration ratio values, while ²³²Th/²²⁶Ra and partially ²³⁵U/²³⁸U ratios were associated with the particle sizes vertical distribution. A study of radionuclides in the samples of leaves of two deciduous tree species common for these parks was also conducted and ²¹⁰Pb and ⁴⁰K were found concentrated in leaves rather than other investigated radionuclides.     

Evaluation of radiation dose due to naturally occurring radionuclides in rock samples of different origins collected from Azad Kashmir

The state of Azad Kashmir is rich in three types of rocks, namely, sedimentary, metamorphic, and igneous rocks. These rocks contain extensive deposits of graphite, marble, limestone, quartzite, granite, dolerite, and sandstone, which are widely used for the construction of dwellings in Azad Kashmir and Pakistan. Therefore, knowledge about the presence of natural radioactivity in these materials is desirable to assess the radiological hazards associated with it. In this context, 30 rock samples were collected from different geologic formations of the Muzaffarabad Division, Azad Kashmir. After processing the samples, the specific activities of ²²⁶Ra, ²³²Th, and ⁴⁰ K in them were measured using a P-type coaxial high-purity germanium detector. The observed highest dose rate values for sedimentary, metamorphic, and igneous rocks have been found to be 83.16 ± 1.08, 135.87 ± 1.18, and 115.98 ± 1 nGy ⋅ h^–1, respectively. The radium equivalent activity (Ra_eq) varied from 23.76 ± 1.15 for dolerite sample (igneous rock) to 293.69 ± 2.60 Bq ⋅ kg^–1 for marble (metamorphic rock). The Ra_eq values of all rock samples are lower than the limit mentioned in the Organization for Economic Cooperation and Development (OECD, 1979) report (370 Bq ⋅ kg^–1, equivalent to γ-dose of 1.5 mSv ⋅ y^–1). The values of external (H_ex) and internal hazard indices (H_in) are less than unity. The mean outdoor and indoor annual effective dose equivalents are 0.073 mSv ⋅ y^–1 and 0.29 mSv ⋅ y^–1, respectively. The mean (over all types of rock samples) annual effective dose equivalent is reported as 0.36 mSv ⋅ y^–1.     

Radiation impact assessment of naturally occurring radionuclides and magnetic mineral studies of Bharathapuzha river sediments,South India

The natural radioactivity levels and magnetic measurements in sediment samples of Bharathapuzha river for the first time have been determined. Bottom sediments from 33 locations were collected to determine ²²⁶Ra, ²³²Th and ⁴⁰K using a HPGe detector based on the high-resolution gamma spectrometry system, and magnetic susceptibility by using Bartington MS2 magnetic susceptibility meter. The calculated activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K have been found to vary from 21.21 to 66.03 Bq kg^?1, 33.49 to 93.10 Bq kg^?1 and 232.25 to 899.66 Bq kg^?1, respectively. The results have been compared with worldwide recommended values and also with radioactivity measurements in river sediments of India and other parts of the world. The air-absorbed dose rate, indoor and outdoor annual effective dose rates and radium equivalent activity are calculated with an aim to access the radiation hazards arising due to the use of these materials in the construction of buildings and their mean values obtained are 74.83 nGy h^?1, 367.08 μSv y^?1, 91.77 μSv y^?1 and 157.09 Bq kg^?1, respectively. The mass-specific magnetic susceptibility values ranged widely from 35.4 to 2,160.5 × 10^?8 m³ kg^?1 and compared with other rivers in South India. Multivariate statistical analyses were performed to describe the magnetic and radioactivity relevance of the different groups of samples. The data obtained in the present study may be useful for radiological and magnetic mapping of the study area in the future.     

Petrology and geochemistry of A-type granites from Khanak and Devsar areas of Bhiwani district,southwestern Haryana

Petrological and geochemical characteristics of the granites from the Khanak and Devsar areas have been discussed in this paper. Based on field, petrographical and geochemical observations, three types of granites (grey, green and pink granite) have been identified in these areas. Grey granites consist of quartz, plagioclase, biotite, hornblende as essential minerals and hematite, zircon, annite, monazite & rutile as accessory minerals. Petrographically, green granites are same as grey granites including perthite and zircon as accessory minerals. Pink granites consist of quartz, k-feldspar and biotite in Khanak whereas in Devsar granites alike as Khanak granites, but plagioclase is replaced by perthite and occurs as dominantly. Microscopically, granites of both areas show porphyritic, hypidiomorphic, granophyric, perthitic and micro granophyric textures. Geochemically, major oxide elements (except alkalies) and trace elements (Ba, Sr, Cr, Ni, V, Cu, Zn, Ga, Pb, Th and Zr) are more in green and grey granites of Khanak and Devsar areas than pink granites. Generally, they show enrichments in SiO₂, Na₂O+K₂O, Fe/Mg, Rb, Zr, Y and and AI (Agpaitic Index) (ranges from 0.10 to 1.18) and depletion in MgO, CaO, P, Ti, Ni, Cr and V indicate their A-type affinity which is very similar to the A-type granites of MIS (Malani igneous suite) in northwestern peninsular India. Green and grey granites of Devsar area show high concentrations of Heat production (HP) 9.68 & 11.70 μWm^-3 and total Heat Generation Unit (HGU) i.e 23.04 & 27.86 respectively. On the other hand, pink granites of Khanak area display a higher enrichment of HP (16.53 μWm^-3) and HGU (39.37) than those granites of Devsar area. Overall, they have much a higher values of HP and HGU than the average value of continental crust (3.8 HGU), which imply a possible linear relationship with the surface heat flow and crustal heat generation in the rocks of MIS. From the petrography as well as the chemistry of Khanak and Devsar granites, it is suggested that they might have derived from the different degree of partial melting from the similar source of magma.     

Dynamics of sediment and contaminant transport in the Hudson River estuary: Evidence from sediment distributions of naturally occurring radionuclides

Near surface (<10 cm) sediment distributions of²³⁴Th sampled multiple times at five locations along the axis of the Hudson Estuary from the Upper Bay of New York to Haverstraw Bay are compared with²¹⁰Pb data from longer cores at the same locations. The comparison indicates that while there is little net sediment accumulation anywhere except at one location in the Upper Bay, near surface sediment in this reach of the estuary is mobile on short (months) time scales. The sediment appears to be physically mixed rather than bioturbated. Comparison of the sediment inventories of²³⁴Th with calculated water column production indicates short time scale (months) variability in²³⁴Th deposition. Some parts of the bottom have²³⁴Th inventories in excess of local production but these appear to be balanced by²³⁴Th deficient areas, resulting in a general equilibrium. Sediment inventories of Pb, Cu, and Zn normalized to²¹⁰Pb show no evidence of a uniquely urban source of these metals to the lower estuary. Silver distributions in sediment indicate a possible source of silver from New York City, probably related to sewage inputs.     

Measurement of soil-gas radon in some areas of northern Rajasthan,India

The health hazards of the radioactive gas radon on general public are well known. In order to understand the level and distribution of ²²²Rn concentrations in soil-gas in Sri Ganganagar district of Rajasthan, a ²²²Rn survey was carried out for the first time using RAD7, an electronic radon detector manufactured by Durridge Company (USA), at different locations covering a total area of 10,978 km ², having a population of approximately 20 lakh. The measurement of ²²²Rn concentration in soil-gas was carried out at four different depths (10, 40, 70, and 100 cm). The radon concentration in soil-gas for 10, 40, 70, and 100 cm depths ranged from 0.09–4.25, 0.15–6.30, 0.50–9.18, and 0.72–10.40 kBq m ^?3, respectively. The minimum value of radon concentration is observed in 33 GB village at 10 cm depth and maximum for Mohanpura village at 100 cm depth. As expected, our data show an increase of soil-gas radon concentration levels with depth. The present results are compared with the available radon data from other studies.     

Precambrian phosphorites in the Bijawar rocks of Hirapur-Bassia areas,sagar district,madhya pradesh,India

The Precambrian phosphorites of Bijawar Group of rocks show characteristics of a epicontinental sea with restricted and very shallow marine environment of formation along some shoals, which existed during the iron-rich Precambrian times. These phosphorite deposits located in the Hirapur-Bassia areas show extensive leaching of carbonate and phosphate minerals during episodes of weathering. X-ray diffraction studies indicated that carbonate-flourapatite is the major apatitic phase in these phosphorites while crandallite developed on the surface outcrops. There is a general tendency for the depletion of CO₂ in these apatites leading to formation of flourapatite. This CO₂ is an indicator of hidden weathering in the rocks. Major and trace element determinations of phosphorite have been used to indicate various correlation factors responsible for the concentration of elements in these Precambrian leached phosphorites.The paper is a contribution to the aims and objectives of IGCP Project 156The paper is dedicated to Prof. Dr. R. C. Misra, who as a teacher and guide had been a source of inspiration to the senior author for the last two decades     

Chemico-petrographic studies of some lignite core samples from Kalol oilfield,Cambay Basin,Gujarat, Western India

The Kalol oilfield in the Cambay graben, Gujarat. western India, is known to contain thick seams of lignite in the Kalol Formation (Middle Eocene), overlying the oil-bearing Cambay Black Shale (Lower Eocene), at depths between 1110 m and 1500 m. The Kalol Formation occurs in the northern portion of the Cambay Basin as a wedge-shaped sequence of regressive and transgressive marine environments, the lignite being confined to the former phase.Chemically, the Kalol lignite is characteristically low in moisture (4.45–4.64%), quite low in ash (1.67-10.82%) and high in volatiles (43.56–55.25%). C is 72.39–77.18%, H is 4.47–5.93%, N is 1.16–1.58%, O is 15.73–18.62%, and S is 0.32–0.86%. According to Seyler's classification, the Kalol lignite can be classified as belonging to rank (a) lower than lignitous, (b) perlignitous, (c) ortholignitous, (d) metalignitous, and (e) bituminous. According to North American (ASTM) classification, utilising data on volatiles and R_{m oil}, the lignite belongs to lignite, sub-bituminous C and low volatile bituminous rank.Petrographically, the Kalol lignite is composed of huminite (50–81%), liptinite (1–16%), and inertinite (6–32%). Inertinite comprises mainly sclerotinite as plectenchyma, fusinite being absent. Exsudatinite is quite common. On the basis of microlithotype, the lignite comprises textile (1–13%), detrite (19–69%), liptitextite (1–10%), liptidetrite (4–16%), inertidetrite (1–25%), detrinertite (3–21%), and inertite (5–26%), with shale (5–12%). R_{m oil} varies from 0.30 to 0.40. The bituminous coal sample is high in shaly matter (53%) and composed of vitrinite (16%) and sclerotinite (29%), the former showing R_m 1.80.These studies indicate that the chemical and petrographic constitution of the lignite is favourable for underground gasification.     

Mineralogical evolution of indium in high grade tin-polymetallic hydrothermal veins — A comparative study from Tosham, Haryana state, India and Goka, Naegi district, Japan

Two tin-polymetallic vein-type deposits widely separated in time and space but with strong similarities in terms of mineralization style, ore mineralogy and chemistry have been studied comparatively with the aim of understanding the mineralogical evolution of In-rich hydrothermal systems. The Tosham deposit, Bhiwani district, Haryana, India, is of Neoproterozoic age and constitutes a Sn–Cu prospect with unusually high In content. The disseminated, crude stockwork and vein mineralization is hosted by greisenised metasedimentary rocks intruded by a porphyritic granite stock and by later rhyolitic effusives. The Goka deposit, Naegi district, Japan is probably of uppermost Cretaceous age and occurs close to a well fractionated ilmenite series granitoid body. The tin-polymetallic vein in the Goka deposit is hosted by a welded tuff unit close to a subvolcanic granodiorite porphyry.The main host minerals of indium in the Tosham and Goka ores are sphalerite, stannite, unidentified Zn–Cu–Fe–In–Sn–S phases and chalcopyrite. Up to 0.48 wt.% In has been noted in the Goka chalcopyrite, whereas at Tosham, the mineral has a maximum In concentration of 1220 ppm. At Goka the sphalerite contains up to 1.89 wt.% In, whereas In-bearing stannite carries up to ca. 9 wt.% of the metal. Roquesite is the other indium mineral present in the Tosham ores, but is absent in Goka. The mineral chemistry of the Tosham and Goka ores suggest that the In-bearing minerals belong to a multi-component Zn–Cu–Fe–(Ag)–Sn–In–S system. Based on various triangular plots of the atomic proportions of the main metals, it is inferred that there are end-member phases, roquesite and stannite, in the Tosham ores co-existing with chalcopyrite. The sphalerite is both pure end-member and Cu–In-bearing in both the Tosham and Goka ores. Some of the analysed stannite grains in Tosham ores could possibly be petrukite. The Zn–Cu–Fe–Sn–In–S system in the two ores has a Sn-poor, high-In solid solution phase and also a Sn-rich, low-In solid solution phase. It seems possible that these two solid solutions were the first to form during hydrothermal ore deposition at high temperatures from a disordered solid solution located at the (Cu + Ag):(Zn + Fe):(In + Sn) = 3:5:2 intersection in the (Cu + Ag)–(Zn + Fe)–(In + Sn) field. With decreasing temperatures, the Sn-poor, In-rich solid solution exsolved the Zn–In-mineral of Ohta [Ohta, E., 1980. Mineralization of Izumo and Sorachi veins of the Toyoha mine, Hokkaido, Japan. Bulletin, Geological Survey of Japan 31, 585–597. (in Japanese with English abstract).] and sphalerite, while the Sn-rich, In-poor solid solution was broken down to stannite and relatively-Cu-rich sphalerite.     

GIS based spatial distribution mapping and suitability evaluation of groundwater quality for domestic and agricultural purpose in Kaithal district, Haryana state, India

Groundwater is a major resource for meeting huge domestic and agricultural requirements of Kaithal district in Haryana. Therefore, evaluation of its quality in terms of suitability for domestic and agricultural sectors is necessary for sustainable management of the resource. The present study has analyzed pre- and post-monsoon physico-chemical data of groundwater samples from bore wells spread over the entire district. Spatial distribution maps were generated for hydrogen ion concentration, total dissolved solids, total hardness, electrical conductivity, sodium adsorption ratio, residual sodium carbonate and percent sodium using the geographic information system. Furthermore, the study area was demarcated into different groundwater quality zones for domestic and agricultural use by applying various national and international standards. It was observed from the study that the groundwater was predominantly hard, alkaline and saline in nature. However, it was within safe limits for domestic use. Further, it was also experienced from the analysis that in about two-third parts of the district, groundwater was in desirable-to-permissible quality class for agricultural use but hazardous for soil as well as for crops in the remaining part. Also, a moderation in water quality was observed after the monsoon season, which can be attributed to a possible dilution due to groundwater recharge.     

Enrichment characteristics of radioelements in various types of rock from Sambalpur district,Orissa, India

Over the years a large number of rock samples were collected by the explorationists of Atomic Minerals Directorate for Exploration and Research (AMD), Department of Atomic Energy from Sambalpur district, Orissa, India. The variation of uranium enrichment with various types of rock in these samples was studied with an aim to help quick reviewing of toposheets in case of newly taken up areas, for uranium exploration. The radioelements U, Th and K determined for these samples are plotted in ternary diagrams for classifying them as being uraniferous or thoriferous with respect to various type of rocks, keeping the total natural content of radioelements (expressed by eUP₃O₈) as a parameter. In this study it is seen that samples of quartzofeldspathic breccia type are enriched in uranium irrespective of their further sub classification and eU₃O₈ content. Granites are enriched in thorium when eU₃O₈ < 100 ppm and are enriched in uranium when eU₃O₈ > 100 ppm. A database prepared for this purpose may be useful for reviewing toposheets in future     

Radiological risk assessment of naturally occurring radioactive materials in marine sediments and its application in industrialized coastal areas: Bay of Algeciras,Spain

Radioactivity levels in aquatic environments can be assessed through the study of superficial sediments. Anthropogenic activities may alter radioactivity levels leading to the anomalous accumulation of natural radionuclides in coastal areas. In this work, marine sediments from a significant area subjected to severe industrial development were collected in order to measure activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K by gamma spectrometry. Radium equivalent index (Ra_eq), absorbed gamma dose rate in air (D) and annual effective dose equivalent (H) were also calculated and used as risk assessment tools. Results showed low levels of radioactivity in marine sediments from the Bay of Algeciras, discarding any significant radiological risks. Furthermore, the obtained data set could be used as background levels for future research applications and development of environmental regulatory frameworks.     

Application of cubic spline in soil erosion modeling from Narmada Watersheds,India

Soil erosion by water is ubiquitous, exhibits spatio-temporal variability, and is fundamental to determining sediment yield which is key to proper watershed management. In this study, we propose a relationship between the curve number and sediment yield index (SYI) using cubic splines. Using field data from four watersheds, the relation between observed and computed SYI is found to have a coefficient of determination (R²) value from 0.63 to 0.88 suggesting that such a relation can be used to determine SYI from the available CN value. It is found that cubic splines perform satisfactorily with Nash-Sutcliff efficiency ranging from 60.18 to 64.01%, absolute prediction error from 1.35 to 5.56%, integral square error from 1.21 to 5.82%, coefficient of correlation from 79.32 to 93.78%, and degree of agreement from 0.87 to 0.99%.     

Deformation style in the Granulite-charnockite province of South India: An example from the Kusulmalai area in Salem district,Tamil Nadu,India

A multiple-deformation sequence is established for different types of gneisses, mafic-paleosomes and banded magnetite quartzites (BMQ) exposed within the area. In gneisses, the basin-shaped map pattern represents the type-i interference structure formed due to the overprinting of F₃ folds with ENE striking axial planes on F₂ folds with axial planes striking NNW. The BMQ band occurring as an enclave within the gneissic country, represents a large scale F₁ fold with relatively smaller scale F₂ folds developed on its limbs. Mafic-paleosomes within the streaky-charnockitic-gneisses exhibit structures formed due to the interference of more than two phases of folding (F₁,F_la,F₂,F₃). It is shown that the deformation plan in these rocks is consistent with the generalized deformation scheme for Granite-greenstone belts. The difference in the map pattern of Granite-greenstone belts and Granulite-charnockite terrains is ascribed to the variance in Theological properties, layerthickness ratios and local displacement directions during different phases of folding. These differences apart, both the Granite-greenstone and Granulite-charnockite provinces in South India are deformed by an early isoclinal folding which is successively overprinted by folding on NNW and ENE striking axial planes.     

Source and distribution of metals in urban soil of Bombay,India, using multivariate statistical techniques

Simplification of a complex system of geochemical variables obtained from the soils of an industrialized area of Bombay is attempted by means of R-mode factor analysis. Prior to factor analysis, discriminant analysis was carried out taking rock and soil chemical data to establish the anthropogenic contribution of metals in soil. Trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) are expressed in terms of three rotated factors. The factors mostly indicate anthropogenic sources of metals such as atmospheric fallout, emission from different industrial chimneys, crushing operations in quarries, and sewage sludges. Major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, and Fe) are also expressed in terms of three rotated factors indicating natural processes such as chemical weathering, presence of clay minerals, and contribution from sewage sludges and municipal refuse. Summary statistics (mean, standard deviation, skewness, and kurtosis) for the particle size distribution were interpreted as moderate dominance of fine particles. Mineralogical studies revealed the presence of montmorillonite, kaolinite, and illite types of clay minerals. Thus the present study provides information about the metal content entering into the soil and their level, sources, and distribution in the area.     

Identification and mapping of some soil types using field spectrometry and spectral mixture analyses: a case study of North Sinai, Egypt

This study examines linear spectral unmixing technique for mapping the surface soil types using field spectroscopy data as the reference spectra. The investigated area is located in North Sinai, Egypt. The study employed data from the Landsat 7 ETM+ satellite sensor with improved spatial and spectral resolution. Mixed remotely sensed image pixels may lead to inaccurate classification results in most conventional image classification algorithms. Spectral unmixing may solve this problem by resolving those into separate components. Four soil type end-members were identified with minimum noise fraction and pixel purity index analyses. The identified soil types are calcareous soils, dry sabkhas, wet sabkhas, and sand dunes. Soil end-member reference spectra were collected in the field using an ASD FieldSpec Pro spectrometer. Constrained sum-to-one and non-negativity linear spectral unmixing model was applied and the soil types map was produced. The results showed that linear spectral unmixing model can be a useful tool for mapping soil types from ETM+ images.